Visualyse Interplanetary User Guide

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Introduction

Welcome to the Visualyse Interplanetary User Guide

Visualyse Interplanetary is a software tool that allows you to simulate a wide range of radiocommunication systems, and the potential interference levels between them. This User Guide provides all the information you need to operate the software.

In other documents you will find the User Guide for the add-on Modules, a Tutorial, a Technical Annex giving background to the calculations, and a description of each of the example files.

Our assumptions about you, the User are that you are an engineer of some kind and that your understanding of radio systems and interference issues is good. We assume that you are mainly looking for guidance on the operation of the software.

Therefore the main aim of this Guide is to show you how to map your real world understanding onto the abstract models and concepts in Visualyse Interplanetary. This is relatively easy to do as the concepts and models in Visualyse Interplanetary are based on our analysis of the real world of radiocommunications, and we anticipate significant overlap between our world and yours.

We recommend that you read at least the overview section thoroughly. Other sections of this User Guide can be used as reference books when you are building and editing your simulations. If you are a typical user you will be able to make some good progress by experimenting with the software itself – perhaps after having followed the Tutorial.

This section of the User Guide gives an overview of the software. It explains at a high level what the software can do and also serves as a road map to rest of the guides.

Other sources of information include:

• The example files shipped with the software, plus the document describing them

• Telephone technical support (if you have a current Annual Maintenance and Support contract)

• Web site:

  https://www.transfinite.com

• User group newsletter – issued periodically to everyone with an Annual Maintenance and Support Contract

• Training courses – by arrangement with the Transfinite Systems

About The User Guide

• What is Visualyse Interplanetary?

• Visualyse Interplanetary as an Interference Analysis Tool

• Visualyse Interplanetary as a General System Analysis Tool

• Visualyse Interplanetary Windows and View

• How to Create and Change Things in Visualyse Interplanetary

• Add, Edit, Duplicate and Delete

• The Example Files

What is Visualyse Interplanetary?

Visualyse Interplanetary has been designed to simulate radio systems and to analyse potential interference between such systems.

Visualyse Interplanetary will allow you to faithfully model many types of radio system and provides support for the definition of terrestrial networks, space based systems, radar, fixed and mobile communications.

Its range of built-in antenna and propagation models means that most of the time the elements needed to model your system, even if the systems as a whole is innovating and new, are already there and you simply pick them from list.

Increasingly we find that people are using Visualyse Interplanetary for other types of modelling, and this is possible due to the open and flexible design of the software.

Visualyse Interplanetary can be used for many other types of analysis, and users are supported in this by the graphical feedback, the possibility to track and analyse internal variables and the simple underlying model that the software uses.

Graphical Feedback

An important feature of Visualyse Interplanetary is the graphical interface and the animated interactive views. The feedback from these views allows complex simulations to be set-up and more easily verified.

You will see immediately if you create a station or a link and it is not in the location you intended. The dynamics of your scenario can be displayed on a variety of map projections.

Graphs showing the evolution of any variable or statistical information on any variable are also interactively updated.

Not a Black Box

Engineering software is often presented as a black box system. This means that you set up your input and the software tells you an answer, with little or no explanation. In some applications you may see improvements on this and have results presented at several levels of detail.

In Visualyse Interplanetary, details of every calculation can be displayed and analysed - using Model Views, Table Views and Watch Windows and in statistical form as histograms or cumulative distributions. This is true for every variable whether specified as an initial input (it may after all evolve), whether a direct output, or whether part of some intermediate calculation.

Any variable can be written to a text file and logged at each time step for external analysis and processing if necessary. This option allows you to completely verify the calculations against external standards.

Object Orientation

The data needed to define a simulation are entered via a series of dialogs: one for each of the Visualyse Interplanetary modelling elements. The modelling elements reflect real world objects and concepts from radiocommunications.

As such, communications engineers should be familiar with the modelling concepts with Visualyse Interplanetary and may find the software intuitive and simple to use.

The next sections explain this main function of Visualyse Interplanetary, as an interference analysis tool. Build on Simple Foundations outlines some of the other uses of the software.

Visualyse Interplanetary as an Interference Analysis Tool

The structure of Visualyse Interplanetary reflects its core function as an interference analysis tool. User defined elements are the basic building blocks. These elements include Antennas, Carriers, Stations and Links.

An overview of how the building blocks fit together is described in Overview of Visualyse Interplanetary.

Basic Modelling Elements

The basic process in setting up interference scenarios is to define radio stations and to link them together – Visualyse Interplanetary includes objects called Stations and Links.

In the real world stations use antennas and so Visualyse Interplanetary has an Antenna object to model the behaviour of antennas. A Station in Visualyse Interplanetary is defined by a location, rules for its movement and the antennas it uses and how it points them.

Links can be defined by a start and end Station and include details of EIRP, Frequency and each has a specified Carrier.

Having defined the basic modelling elements, Links can then be selected as wanted or interfering (or both), and this reflects our experience of how spectrum sharing and interference analysis studies are conceptualised.

Antennas, Carriers, Stations and Links contain almost all the information needed to perform interference calculations.

Stations and Links can be placed into Groups e.g. satellite constellations can be treated as a single Group of Stations, multiple uplinks to a single satellite can be treated as a Group of Links. Analysis of Groups of Stations and Links allows large scenarios to be analysed more easily.

Define the Required Output

Interference can be analysed in terms of:

• C – the wanted carrier level
• I – the interfering carrier level
• N – the wanted system noise
• C/I
• C/N
• C/N+I
• I/N
• PFD – the Power Flux Density
• EPFD – the Equivalent Power Flux Density

Interference can be from a single source or aggregated from multiple antennas on multiple Stations.

Where interference or wanted signal levels vary with time (due to the motion of stations, signal fading or perhaps some other time dependent effect), Visualyse Interplanetary can collect and display statistical information.

Propagation Modelling

In Visualyse Interplanetary you can select from 22 propagation models and apply them alone or in combination to Visualyse Interplanetary Links.

As different models may apply in different environments, you can define any number of link ‘Types’ and have a different set of propagation conditions for each. By default you will see there are the following Link Types:

• Terrestrial Fixed
• Terrestrial Mobile
• Space to Earth
• Space to Space
• Broadcasting

Interference Calculation

The interference calculation that Visualyse Interplanetary performs requires you to specify:

1. Your wanted or victim link(s)
2. The unwanted or interfering link(s)
3. A number of calculation options

In default configuration the software will take the carrier centre frequency and bandwidth that you have specified and calculate the overlap between the wanted and unwanted carriers.

It will perform an aggregation based on the power sum of all the unwanted sources, taking into account their relative power levels, antenna gain (calculated based on geometry), path loss etc.

There are a number of additional factors that can be included in the calculation. For example:

• The net filter discrimination calculated from the transmit and receive spectrum masks
• Polarisation isolation
• Possible multiple hits from a narrow band unwanted carrier to a broadband wanted
• Radar ‘on tune rejection’.# Interference Calculation

Build on Simple Foundations

Although based on the combination of very simple elements, it is very easy to create scenarios that are large and complex using Visualyse Interplanetary.

The software supports you in the complex analysis through:

• Grouping of Station and Link objects
• Use of Wizards to create and modify groups – for example, the Service Area Wizard that allows you to create (among other things) large numbers of hexagonally deployed terrestrial stations, or the Link to Service Area Wizard that will allow you to connect all these Stations in multiple Links.
• Import of data from various external sources, including the space and terrestrial IFICs or from a simply formatted grid (or CSV file) that you can define and edit in your windows compatible spreadsheet.
• Definition of ‘Dynamic Links’ and complex ‘Tracking Strategies’ that allow you to model networks that may include handover
• Modelling traffic variations (with use of the Traffic Module)
• Use of Monte-Carlo modelling for any variable (with use of the Define Variable Module)
• Use of terrain data, land use and clutter data in our propagation models (with use of the Terrain Module).

These and other features allow you to refine and expand simple scenarios into large and accurate representations of sharing scenarios.

The key point is that it is simple to learn the basic operation of the software and simple models for the basis of much more complex ones.

This is true of general modelling and analysis (described in the next section) as it is of communications and interference modelling.# Build on Simple Foundations

Visualyse Interplanetary as a General System Analysis Tool

The flexibility and basic design of Visualyse Interplanetary means that it can be used for many purposes other than interference analysis. All the variables contained in the simulation are open to the user and can be charted and exported for further processing.

You can collect statistics on any variable in the simulation – a feature whose usefulness is unlimited.

Some indication of the flexibility of the software can be given by the following list of possible use. This is in no way exhaustive.

• Terrestrial network deployment and coverage analysis
• Visualisation of the geometry and dynamics of complex scenarios
• Antenna Beam and Footprint display
• Satellite Constellation definition and analysis
• Coverage and service level analysis.
• End to end performance analysis of multi-hop systems
• Path loss analysis
• Link multipath fading analysis
• Link Budget Analysis
• Production of maps containing features from the ITU IDWM data
• Analysis of visibility statistics for non-GSO satellite constellations

Most probably you have bought Visualyse Interplanetary to do interference analysis, but as your experience and confidence with the tool grows; you will find many other ways to use it.

Visualyse Interplanetary Windows and View

The structure of Visualyse Interplanetary is referred to as a “Document-View” architecture.

Your simulation information is all contained in a Visualyse Interplanetary document. This is a file with extension .sim. A document is a simulation plus all the collected data, current state information and current configuration parameters.

The information in the document can be analysed through several ‘Views’, such as Map views, Model View or Graph Views. Multiple views of multiple documents can be open at the same time. Each offers a different perspective on the same information.

Visualyse Interplanetary simulations can be viewed using the following types of windows:

• Flat projection Map View - this is a rectangular projection of the earth's surface. When a Map View is created the projection is either Plate-Carrée or Mercator projection.
• 3D View - this is a perspective projection of the Earth and surrounding orbits, viewed from a point in space.
• Watch Window - in the watch window, select simulation variables to watch as they evolve. The variable is presented in textual form.
• Model View - the Model View shows a hierarchical view of the simulation elements. You can create, edit, save and load objects from this view.
• Data vs. Time graph - this is a graph of any variable in the simulation against simulation time, updated interactively.
• Distribution chart - this view is used to show probability distributions and cumulative distributions calculated during a simulation.
• Data vs. Data graph - this allows any two Visualyse Interplanetary variables to be plotted against each other on a scatter plot.
• Frequency View – this shows graphically the relative centre frequencies of the wanted and a selected interfering link together with the interferer’s transmit spectrum mask and victim’s receive filter

If you have the Visualyse Interplanetary Terrain Module, there is also the:

• Path profile view that will show the terrain spot heights along any chosen great circle path.

All views can be configured: if you right mouse clicking in the view, outside the active plot area, it will bring up the properties dialog. This is equivalent to selecting Configure from the View menu.

Map and 3D Views

The flat projection map and 3D windows provide animated views of the simulation geometry and connectivity i.e. where the Stations are, where they are going and which Stations are connected together. These views can also be used to plot antenna coverage, colour coded or contoured area analysis and to display overlays on top of a simulation.

As a snapshot of the scenario you are simulating for a report or for your own verification purposes, these views are invaluable.

Watch Window

The watch window is a way of monitoring the evolution of selected simulation variables.

Select and order a list of variables and watch as they are interactively updated as the simulation runs.

The data in the watch window can be copied at any time using the copy button at the top right. The copied data can be pasted into other applications (for example Microsoft Word or Excel) in a tab delimited form.

Model View Window

The Model View shows the structure of a simulation in a hierarchical arrangement of objects and their parameters. Simulation objects can be added, edited, duplicated, deleted, loaded and saved from this view.

Save and Load options allow you to save and object and it’s parameters to a text file. This allows you to edit the object externally and reload with new data.

Graph Windows

There are three kinds of Graph Windows allowing variables and statistics to be plotted. The three graph types are:

• Data vs. Time graph
• Data vs. Data graph
• Distribution charts

Data vs. Time graphs allow an interactive monitor to be placed on any simulation variable. Interference levels and event profiles can be obtained using a Data vs. Time graph.

Data vs. Data graphs are scatter plots, whose axes can be any two variables in the simulation. An example use of a Data vs. Data is to plot the azimuth and the elevation of an antenna on the same plot.

Distribution charts are used to plot histograms and cumulative distribution functions. These plots can only be used for those variables that you have asked Visualyse Interplanetary to collect statistics on. In the default configuration, Visualyse Interplanetary collects no statistics until asked.

All three types of graph are produced using software provided by Graphics Server. Many configuration options are provided via the Graph Control, which is described in detail in the Configuring Graphs.

How to Create and Change Things in Visualyse Interplanetary

Objects are created and changed in Visualyse Interplanetary via dialogs. Each dialog consists of a number of sheets (or tabs) via which the relevant parameters are entered.

There are a number of ways to access the dialogs:

Via the toolbar – for example, clicking the Station icon will bring up the Station List. This shows all the Stations in the current simulation, and gives options to Add, Edit, Duplicate and Delete.

Via the menus – element lists can all be accessed from the Model menu.

Via the Model window – you can create new elements by clicking on the “Add” button. Editing can be achieved by double clicking or right clicking a particular object.

Add, Edit, Duplicate and Delete

For inputting and editing system data, you will work with Visualyse Interplanetary object lists.

So, for example, when you click the Station icon, you will be presented with the station list:

Note at the bottom of the list the four functions ‘Add’, ‘Edit’, ‘Duplicate’ and ‘Delete’.

These are common to all the list dialogs and are used for management of the list

The Example Files

Visualyse Interplanetary is installed with a number of pre-configured example files. The example files cover many areas and can provide you with a quick start in the use of Visualyse Interplanetary.

A separate document is available explaining each example file in turn. This document can accessed from the Help menu.

Overview of Visualyse Interplanetary

This section describes the way the structure of Visualyse Interplanetary relates to real world radiocommunications systems, their operation and their compatibility.

Before we discuss the ways in which systems can be built, we need to say a few words about the settings that define the environment in which the systems will operate (chiefly which propagation models you want to use) and settings that tell Visualyse Interplanetary what outputs you are interested in.

These should be considered before you start to model your systems, but can be changed at any point before you start to run the simulation. The purpose of the discussion below is to make you aware of the options that are available.

Propagation Modelling

Propagation modelling in Visualyse Interplanetary is dealt with at simulation level. This means you define a global propagation environment in terms of which loss models to apply to different types of Link, and Visualyse Interplanetary does the rest. The global environment can be over-ridden for each link individually.

Visualyse Interplanetary classifies Links into the following types:

• Terrestrial fixed
• Terrestrial mobile
• Space earth
• Space – space
• Broadcasting
• User defined (as many additional ones as you need)

For each Link type you define a set of propagation models to be applied. Different models to can be applied depending on whether the Link is victim or interferer.

We refer to the whole set of propagation models for the different Link types as the Propagation Environment.

In order the set your propagation environment begin with the Propagation menu (shown below).

To change the models used by a particular Link type, simply select the Link type from the Propagation menu. The properties dialog for the selection will be displayed.

The dialog above shows the models that will be used for terrestrial fixed Links.

You may wish to treat propagation in a different way when considering wanted and interfering signal levels – this is normal practise if you are following ITU-R Recommendations. In Visualyse Interplanetary, a Link can be used as both a victim and interferer.

You can change the models used by clicking the appropriate ‘Change Models’ button. The Propagation models dialog will appear.

You can select any combination of the base propagation models plus any rain or atmospheric models. Visualyse Interplanetary does not restrict the combinations you choose but will generate a warning message (which you can ignore) if you choose two models, each of which has a free space element included in it. This helps prevent double counting of free space loss.

Propagation Model Parameters

Many of the propagation models have associated parameters. You can edit these by double clicking on the model or by selecting it and clicking the Model Parameters button. This will show the propagation parameter dialog for the model. An example is shown below.

A description of the available propagation models is given in the Technical Annex.

Creating Your Own Propagation Link Types

You can create your own propagation Link types – an example application might be if you are modelling a mobile system with go and return links on widely different frequencies. In this case you may want to have ‘UHF Mobile’ and ‘VHF Mobile’ modelled as different Link Types.

To do this, select Advanced from the Propagation menu. The custom propagation Link types dialog will appear.

Click Add to add a new Propagation Link type. The edit dialog for the new Link type will appear. This is the same as the dialog for built in Link types, except that there is a field for the name at the top of the dialog.

Make your changes and click ok. You will be returned to the previous dialog. Click Close and then click the Propagation menu again. You will see your new propagation Link type under the built in Link types.

The Technical Annex contains a tutorial on propagation which is a useful introduction for the non-specialist on the selection and use of propagation models for interference analysis.

What to Calculate and how to Collect Statistics

The Output Menu is where you tell Visualyse which types of data to collect and which specific parameters to write into a log file.

Where the analysis you are performing is dynamic, data is collected in statistical form. At each time step or sample point the output data is recorded in a ‘bin’ of a histogram. Over time the histogram becomes the probability distribution for that data.

Visualyse Interplanetary will not by default record actual values of a parameter at each time step – this would require enormous amounts of memory. We do, however, have a log file option that allows you to select parameters for logging.

This is useful for post-processing and validation – normally the output from Visualyse Interplanetary is statistical information on Link parameters.

Antennas, Stations, Carriers and Links

Now we come to the main modelling elements, through which you define your systems and scenarios.

The structure of the software underlying Visualyse Interplanetary is based on an object-oriented analysis of radiocommunications systems and interference analysis. The objects and the relationships between objects will seem familiar to most engineers.

However, there may be some differences between the Visualyse Interplanetary model and your model of the world of radiocommunications. It is important that the exact structure of the software is understood if you are to gain maximum benefit from the tool.

The following sections describe the Visualyse Interplanetary simulation elements at the top level. Each section provides examples of how these elements map on to objects in the real world and is intended to provide an overview of the structure of the software. This section does not provide a detailed description of the dialogs which is given in Creating and Editing Simulation Objects of this guide.

The fundamental modelling elements that you will need to include in any interference modelling scenario are:

• Antennas
• Stations
• Carriers
• Links
• Interference Paths

Other elements are:

• Tracking Strategies
• Station Groups
• Link Groups

Antennas

Antenna performance has a significant impact on wanted signal levels and on interference levels. Antenna gain is directional and Visualyse Interplanetary allows you to model this directivity in 3-dimensions in a number of ways.

To begin defining a communications system we start by defining the performance of the Antennas that we will use in the modelling. You create and edit antennas either from the Model menu or by clicking the Antenna icon on the Toolbar. The Antenna List will appear.

The figure below shows an Antenna List when three Antennas have been created – by default the List will be empty.

There are several types of Antenna in Visualyse Interplanetary:

• Single beam antennas
• Multiple beam antennas (with many different beams)
• Multiple beam antennas (with many identical beams)
• Spot Beam Pattern Antennas – with spot beams arranged in symmetric patterns
• Satellite PFD mask beams – gain is calculated to provide a given PFD level at defined elevation (or Alpha) angles.

Within each type there are several ways to describe the beams used:

• Circular – defined by data or gain mask
• Elliptical – defined by data or gain mask
• Shaped – defined by data
• Contour – defined by iso-gain contours

Visualyse Interplanetary includes over 80 predefined masks that cover ITU Recommendations, Radio Regulations, ETSI Standards and many other popular masks. Full details are given in the Technical Annex. You can also define roll-off in a look up table.

If your antenna is shaped, you can define a table of gain in two dimensions (antenna pointing angles) or can use GIMS contours. Visualyse Interplanetary provides a simple facility to create and edit GIMS contours.

Stations

The role of Stations is to define the geometry and dynamics of the analysis – where are the transmitters and receivers and where will they be in the future.

Stations also contain Antenna objects and points the Antennas according to one of a selection of pointing methods.

When you create a new Station you are given the option to select from the following types:

• Ground
• Fixed
• Mobile
• Maritime
• Aeronautical
• Stationary Satellite
• Satellite satellite

Visualyse Interplanetary internally distinguishes Station Types by the information you need to provide in order to define their dynamics.

Carriers

Carriers are used to define the bandwidth and polarisation parameters to be used in the Links. The carrier dialog is also where you can define spectrum masks that can be used in calculating adjacent channel and out of band interference levels.

For basic calculations the carrier defines the bandwidth. Later, when you set up the interference calculation, you will tell Visualyse Interplanetary what to do when the bandwidths of wanted and interfering carrier are different – this bandwidth overlap option can have a significant effect on results.

It is also important to bear in mind that you will be entering power levels later and that you may already have entered the antenna gain for the link that this carrier will use – those three parameters together determine the Power Spectral Density.

If you want to consider out of band or adjacent channel then this is the place where you will define the out of band mask.

Links

Links define how the stations are connected together. There are four types of Link in Visualyse Interplanetary:

• Fixed Links
• Transmit Links
• Receive Links
• Dynamic Links

Examples of the different Link types available in Visualyse Interplanetary are given in the following figures.

The figure above shows a satellite to ground station link and a terrestrial microwave link. Both these would be modelled as Fixed Links in Visualyse Interplanetary.

The figure above illustrates the movement of a vehicle through the cells of a mobile phone system. In this case the signal is handed over from base station to base station as the car moves. This would be modelled as a Dynamic Link in Visualyse Interplanetary.

The figure above illustrates the handover from one satellite to another as the first satellite falls below the horizon. This would also be modelled as a Dynamic Link.

The figure above illustrates two examples that would be modelled as Receive Links in Visualyse Interplanetary.

The first represents an earth observation satellite. The second is a scanning radar dish. In both cases, there is no defined wanted transmitter, and the wanted signal level has a known value or is unused. These links could be used to gather information about interference levels, when the wanted signal level is either known or is not relevant.

This figure shows two examples of transmit links. The first is a constellation of non-GSO satellites; the second is a terrestrial broadcast station. In cases where these are considered as interferers only, they would be modelled as Transmit Links in Visualyse Interplanetary.

Example Scenario

The final figure illustrates an example scenario in which a number of wanted Links of different types have been defined from Stations with multiple Antennas.

Interference Paths

An Interference path specifies an interference scenario. This comprises a wanted link or a group of wanted links and a set of interfering links. The purpose of an Interference Path is to calculate the interference from the interfering links into the wanted links.

Tracking Strategies

Tracking Strategies define the criteria for selecting a tracked station from a group of candidate stations. They are used in Dynamic Links to determine the link end station.

There are two types of Tracking Strategy: Predefined and User Defined.

If you cannot find the strategy you need on the predefined list, then you can define your own as a series of geometric constraints on end station selection.

Station and Link Groups

You may find that a Visualyse Interplanetary simulation can become very large very quickly. This is especially true if you are working with constellations of satellites or large groups of terrestrial links.

Visualyse Interplanetary provides a way to simplify the management of large simulations in the form of Link Groups and Station Groups.

Groups can act as simple containers for stations and links – so that all your victim links are in one group and all your interferers in another, for example – or can represent real world groupings such as satellite constellations or fixed service chains.

Visualyse Interplanetary includes ‘Wizards’ to help in the creation of some groups, making the production of complex scenarios much easier.

Full details are given in the Simulation Elements section of the User Guides.

How It Fits Together

• Steps in the Construction of a Visualyse Interplanetary Simulation

• Location of Key Parameters

Steps in the Construction of a Visualyse Interplanetary Simulation

The flexibility of Visualyse Interplanetary means that there is no fixed prescription for setting up and analysing spectrum sharing scenarios. In addition, the number of other uses of the tool mean that there are very many ways you can begin to use the software.

A prerequisite to starting up the simulation is that have a clear idea of the results you are looking for and have a full description of both your wanted and interfering systems.

You need to know the RF, geometric and dynamic characteristics of both systems, and have some understanding of how these characteristics can be represented in Visualyse Interplanetary. This understanding can be gained by reviewing the User Guide, or from the example files and related document provided with Visualyse Interplanetary.

However, if you follow the prescription below you will be able to set up Visualyse Interplanetary to produce C/N+I, C/I and I/N results within a matter of hours.

The recommended steps involved in the creation and analysis of a spectrum sharing scenario are listed below:

1. Define a library of Antennas that will be used
2. Create the Stations, using Station Groups and Wizards where appropriate
3. Define a library of communications carriers via the Carrier dialog
4. Set up your Propagation Environments via the Propagation menu
5. Set up communications Links – both wanted and interfering – using Link Groups and Wizards where appropriate
6. Set up Interference Paths, where wanted and interfering Links are specified
7. Define run duration and time step size using the Time Settings option on the Simulation menu
8. Set up the Output you are interested in via the Output menu
9. Run the simulation
10. Analyse the results via the graphs, watch and table windows, and the various map views.

Location of Key Parameters

In the calculation of C, I, N, C/I, C/N, C/(N+I) and I/N there are a number of key parameters that are defined by your input data. In Visualyse Interplanetary it is sometimes possible to define these parameters in more than one place – this ensures that the software remains more flexible without becoming overly complex. It does, however, sometimes lead to confusion in new users because not every parameter in every dialog is used in the interference calculation.

This section describes where the basic link budgets parameters are or can be defined, and the configuration options under which the parameter will be used.

Wanted and interfering Links are defined in exactly the same way

The Tools Menu

The 'Tools' menu provides access to tools and utilities that allow relationships between many parameters to be calculated and checked.

The equations used by all the tools are described in the Technical Annex.

VisTools

The Tools menu option “Launch VisTools” will start the link budget and radio engineering calculator as shown in the figure below.

Solve for and Optimise

VisualVisualyse Interplanetaryyse provides two tools for performing “what if…” analysis:

The Solve For is used to find the value of a parameter that gives the wanted value for a second parameter.

The Optimize is used to minimize or maximize a parameter, subject to the variation of a second parameter.

Solve For

The Solver can be used to change the value of an object attribute that is dependent on another object attribute. Ordinarily, the only way to change an attribute of this kind is to keep changing the attribute on which it depends until you achieve the desired result. The Solver takes over this trial and error process and does all the hard work for you.

For example, say you had an Earth station communicating with a geostationary satellite. Your problem might be that the satellite should be positioned such that the relative gain at the Earth Station is 2 degrees down from main beam.

You can use the Solver to find the longitude position for the satellite which achieves the requirements for relative gain at the Earth station.

Optimise

The Optimizer is used to maximize or minimize the value of an object attribute that is dependent on another object attribute.

For example, say you had an FS network, and want to create a new hop. What frequency should you use?

The Optimiser can assist you by finding a frequency that minimises interference from all the other FS links.

General User Interface Features

• Right Mouse Button Functions

• Double Click Functions

• Drag and Drop

• Common Dialog Features

• Dynamic Lists

• Naming of Visualyse Interplanetary Elements

• Error Messages

Right Mouse Button Functions

Right mouse clicking can be used to perform many operations in Visualyse Interplanetary. For example:

• Right clicking in the Map, 3D, and Graph views brings up menu options that allows you to change the display properties for the view.
• Right clicking on a Station Icon gives you the option to duplicate or delete the station or to invoke the edit Station dialog.

Double Click Functions

Double clicking on a station invokes the edit dialog allowing you to change the properties of the station.

Double clicking on objects that appear in lists opens the object for editing

Drag and Drop

Station drag and drop is available in the map views if you active the station move icon:

For earth stations and aeronautical stations this allows the latitude and longitude of the station to be changed by clicking on the Station and dragging it to a new position.

Geostationary satellites can be moved along the geostationary arc only.

Dragging and dropping a non-GSO satellite will move the satellite along a fixed latitude by changing the ascending node of its orbit.

Common Dialog Features

Most dialog boxes include the following buttons:

OK - clicking this button confirms and implements any changes you have made then closes the dialog box.

Cancel – clicking this button closes the dialog box without saving the changes you have made.

Apply – saves the changes you have made without closing the dialog box.

Note you do not need to click “Apply” before clicking OK.

Dynamic Lists

As new elements are added to a simulation, they will appear on a list that is accessible via the dialog appropriate to that element. If an element is removed it will disappear from the list.

These lists are referred to as dynamic lists. The use of dynamic lists means that Visualyse Interplanetary places no limits on the number of Stations and other elements that can be defined in a simulation.

Double clicking list items will generally invoke the edit dialog for that item.

Naming of Visualyse Interplanetary Elements

Element names must be unique on each list as it is used to identify that object. Hence, for example, as all Stations appear on the Station list, they must all have unique names.

Error Messages

Visualyse Interplanetary produces error messages whenever an input error occurs. The message consists of three boxes showing:

• the problem
• a description of the error
• a suggestion as to how to carry on

Help Menu

From the help menu you can access the following documents:

• User Guide
• Modules User Guide
• Technical Annex
• Maintenance History
• Tutorial
• Introduction to Example Files

You can also open the About dialog, such as the one below:

This gives important information such as:

• Program version number (here 0.0.18.2)
• Licence site and copy numbers (here Site 1 Copy 1)
• Date of expiry of annual maintenance and support or AMS (here 1/January/2024)
• Active modules (here Traffic, Terrain, DefVar and IDWM)

If the security key or dongle is not identified by the program then the licence site and copy number will be replaced by “Demo”.

Creating and Editing Simulation Objects

This section of the User Guide provides a complete reference to creating and editing Visualyse Interplanetary objects using the simulation dialogs.

In order to benefit from this section you should already be familiar with the bigger picture of the way Visualyse Interplanetary works.

This familiarity can be gained by reading the Overview, by examining the example files and associated documentation or by simply experimenting with the software.

The sections below guide you through each dialog, explaining how to enter the data needed to define your system components, your environmental data, and how to tell Visualyse Interplanetary what to calculate for you.

Antenna Modelling

The Antenna object is fundamental element in Visualyse. In encapsulates the on and off axis performance of antennas in isolation. An Antenna object can then be attached to multiple Stations where the pointing and tracking options are defined.

So, to begin defining a communications system we now start by defining Antennas – either from the Model menu or by clicking the Antenna icon on the Toolbar. The Antenna list will appear.

The figure below shows an Antenna List as it would appear when three Antennas have been created – by default the List will show a single omni-directional, zero gain antenna.

The Antenna list dialog has an integrated roll-off plot in either Polar or Cartesian coordinates to show the variation in gain against off-axis angle for the selected Antenna.

To create a new Antenna, click the Add button. The Antenna types dialog will be displayed.

You then select from one of the five antenna types, by clicking the icon on the left of the list. The five types are:

1. Single beam antenna – this is the simplest choice, the Antenna has a single beam. The beam can be circular, elliptical or shaped.
2. Multiple beams – the most flexible option. The Antenna can have multiple beams with different characteristics. The pointing angles of the different beam boresights are defined individually in terms of azimuth and elevation relative to the antenna mechanical boresight.
3. Multiple Identical Beams – this option is used where an antenna has multiple beams with identical performance characteristics but different point directions.
4. Symmetric Spot Beam Pattern – use this option where the beams in a multiple spot are deployed with circular, hexagonal or square symmetries.
5. Satellite PFD Mask – where the antenna performance is constrained by regulatory PFD limits, use this option to define those limits in terms of elevation angle on the ground (or Alpha angle).

We recommend that you read Creation of a Single Beam Antenna to familiarise yourself with the process of creating antennas. The other subsections below, give additional information needed to define the more complex antennas.

Creation of a Single Beam Antenna

In this section, you will be guided through the process of creating an Antenna with a single beam. The Beam may be circular, elliptical or shaped in cross-section.

Begin by selecting Antenna from the Model Menu

Select the Single Beam option and click Ok. The Antenna properties dialog will be displayed.

Antenna Name

The name of the Antenna (defaults to Antenna Type) is shown in bold in the top left-hand corner of the dialog. When the mouse passes over the name, the cursor also changes to a ‘caret’

If you click on the name, it changes to an edit box so that you can enter a name for your Antenna. This is shown below.

There are four options under Single Beam, each relating to how the cross-section of the beam will be specified. The choice made determines what other parameters are needed to fully define the Antenna.

Each of the input parameter options is now explained in turn.

Beam Cross-section

The beam can be circular, elliptical or irregular shaped in cross section.

The beam shape is selected at the top of the beam tab. As you switch between the options the parameters below the will change.

Circular and Elliptical Beams

For circular and elliptical beams, the gain pattern is defined by the roll-off mask and a few Antenna parameters.

Roll-Off

To change the way the roll-off is defined, choose the Change button next to the roll-off field.

The Roll-off dialog is shown below.

The dialog provides two options. You can use either:

• a standard equation as a mask, or
• a table of gain/off-axis angle pairs

Roll-Off Masks

Visualyse Interplanetary already includes 80 or so standard roll-off masks. These are described in detail in the Technical Annex

Gain Tables

The gain table option allows you to enter the complete roll-off as a set of gain, angle pairs. To help with data entry, you can now copy and paste data to and from different sources, including from Excel spreadsheets.

In this case is no need for you to supply other Antenna parameters such as peak gain and beamwidth. This will be indicated as in the dialog – under Antenna parameters it will say ‘determined by the gain table’.

If the beam shape is elliptical, text will appear above the gain table to indicate that the gain along the semi-major axis is required. In both the circular and elliptical cases, the beam width (as derived from the table) is displayed.

Antenna Parameters

There are four parameters that are commonly used in defining Antenna characteristics. The four are related in standard Antenna theory and no more than two are ever needed to fully define an Antenna.

As an engineer you may know your Antenna diameter but not its beamwidth, or vice-versa. Alternatively, you could be working to a standard antenna and know only the D/

The ‘Antenna parameters drop-down allows you to say which characteristics of the Antenna you know.

Depending on the option selected, a number of applicable fields will appear. You can then fill in these fields with the appropriate information.

For circular beams the combinations are as follows:

• Dish Size & Efficiency
• Full Beamwidth & Peak Gain
• Footprint Diameter

For elliptical beams the antenna must be defined by peak gain and the two beamwidths.

For the case when a gain table defines an elliptical beam, the semimajor axis is determined from the data you have already put into the table (or the default data) and therefore does not need to be entered here. You must however, give the minor axis, and Visualyse Interplanetary will then scale the roll-off in all directions other than along the major axis to give the correct ellipticity.

Beam Roll-off Preview

A preview of the roll-off is shown to the right of the Antenna parameters. You can choose between polar or Cartesian plots. Each plot has its own controls that allow you to modify the display.

For both plots, you can change the slice angle by clicking and dragging the angle control. On the Cartesian plot, you can also zoom into areas of the graph.

In order to understand the meaning of slice angle – if you consider and elliptical beam, the slice angle of the major axis is 0 or 180. The minor axis is 90 or -90.

These plots are provided to give you a basic idea of the shape of your Antenna while you are editing it. Additional plotting options are provided on the Antenna list dialog

Shaped Beams

For shaped beams, a table of gain for various azimuth and elevation () angles replaces the roll-off and Antenna parameters.

The dialog is shown below. The data table is shown in a scrolling window, and has an Edit button to the top left.

To change the table, click Edit. This opens the shaped beam properties dialog shown below.

You can change the size of the table from here. You can copy and paste data to and from the table directly from other sources, including Excel. You can also import from text file in various formats (see Technical Annex for more information).

Contour Beams

Visualyse Interplanetary allows you to create, import and edit antennas that are defined in terms of their gain contours in GIMS format.

You can create and edit beams as polygons using the mouse to click on a map view. This allows you to define coverages from scratch or to approximate coverages that you only have as printed map.

Visualyse Interplanetary provides facilities to import data directly from the ITU database and also to enter contours as polygons using the mouse.

Visualyse Interplanetary then converts these to a grid of gain vs. Antenna angles and stores both the contours and the grid using a proprietary algorithm. In order to do this conversion, Visualyse Interplanetary needs a reference satellite longitude. This is the longitude of the satellite from which the contours were plotted or the longitude at which they will be used. If you subsequently change the longitude of the satellite using the Antenna, the Antenna coverage will move with the satellite.

A new feature is that for patterns imported from GIMS, you can now select the GIMS algorithm for the interpolation of the gain to points in between contours – which ensures compatibility with results obtained using ITU-R software. This option is set in Visualyse Interplanetary Settings (see Visualyse Interplanetary Default Parameters).

The dialog is shown below.

Before you can enter any contours, you need to specify the longitude of the GSO satellite that would host the Antenna.

Next you need to enter the limits on the gain: the peak gain and the gain floor (the limit of relative gain for points along way from the peak gain point). Once you have done this, you can go straight in and add some contours. Click Edit Contours. The Edit Contours dialog will appear.

Setting Network Details

Use the controls at the top to set the name, admin and notice id for the network that the beam is to be a part of.

The orbital position of the satellite is set from the toolbar at the bottom of the window. When you change this, you’ll see that the highlighted area of map representing the satellite field of view will change accordingly.

Adding Boresights

Click the Add Boresight button , then click on the map to add a boresight (hold SHIFT while clicking to add more than one).

Editing Boresights

You can move a boresight by clicking on it, holding the mouse button and dragging it to a new location.

To edit a boresight, first click to select it. You’ll see a small toolbar appear below the selection rectangle. This is called the Selection Toolbar.

From here you can set the relative gain and the exact location in latitude and longitude coordinates. A boresight can also be duplicated and deleted from the selection toolbar.

Adding Contours

To add a Closed Contour, click on the Closed Contour button:

1. Click to add the first point then continue clicking to add more points. You can also hold the mouse button and drag to draw.

2. To complete the contour, click on the first point again or you can double-click to add the last point and finish, or press ENTER.

3. The completed contour is shown as the current selection. Note that you can cancel at any time by pressing ESC.

4. You then need to set the relative gain for the contour. This is shown in the label on the contour itself. By default, it’s set to zero. To change it simply click on it then type in the relative gain you want and either click away or press ENTER.

To add an Open Contour, click on the Open Contour button:

1. Open contours must start on the field of view. When you move the mouse, you’ll see where the first point will be. When you click, both the first point and the clicked point will be added.

2. Keep clicking to add more points. You can also hold the mouse button and drag to draw.

3. Open contours must end on the field of view. When you get close the software will detect this. Simply click to finish. You can also double-click on the last point you want to add, or press ENTER, and the end point will be added automatically.

4. The completed contour is shown as the current selection. Note that you can cancel at any time by pressing ESC.

Editing Contours

Click on a contour to select it. Just like boresights, contours have their own selection toolbar. Buttons are provided to Edit Points, Reduce Points, Smooth Points, Switch to Open Contour, Duplicate and Delete.

Editing contour points is described in the next section.

Reducing the number of points will intelligently reduce the number of points by around half. Smoothing on the other hand will re-sample the contour and add extra points to smooth out any sharp edges.

You can resize a contour by dragging one of the eight control points that surround the selection rectangle.

Editing Contour Points

To edit a Contour (be it Closed or Open), either double-click on it or select it and then press the Edit Points button on the Selection Toolbar or press ENTER.

Click on a point to select it. Hold SHIFT to select multiple points it and then press the Edit Points button on the Selection Toolbar or press ENTER.

Click on the latitude or longitude boxes to make precise positional changes for the selected point

Hold CTRL while hovering on a point then click to delete it. You can also delete any selected points by pressing the DELETE key

Hover near a segment and click to insert a point

You can click on a point and drag it to a new position. You can also use the cursor keys to move the selected point by small amounts up, down, left or right. Hold SHIFT while doing this to move the point by a larger amount each time. The same applies to selections containing multiple points.

Pressing the TAB key will select the next point in the contour and SHIFT + TAB will select the previous point.

To finish editing either click on the Map or another item or alternatively press ESC.

Detaching from the Field of View

As mentioned earlier, open contours should start and end on the satellite field of view. If you drag an open contour, then the end points will always remain on the field of view.

If you want to detach the end points from the field of view, there are a couple of ways to do this. If you want to move the whole contour, then simply click and drag it but hold SHIFT as you do this. The end points will then detach.

To re-attach the end points do exactly the same thing. Once an end point gets close to the Field of View both end points will re-attach at the nearest intersection.

If you only want to move the end points then first edit the contour. Click and drag an end point while holding SHIFT. The point will switch between being unattached or detached. Note that reattaching will only happen when you drag close to the field of view.

Warnings and Errors

You may notice that as you start to construct your shaped beam an orange panel will appear in the bottom-right corner of the application window. This shows any warnings or errors. These are mostly advisory so that you can check your beam will conform to GIMS requirements as you go along.

If there are no errors or warnings, you’ll see this:

If there are any warnings or errors, you’ll see something like this:

Multiple Selections

You can select multiple contours and boresights and then move, duplicate or delete all of them in one go. There are two ways to do this. You can click on an empty area of the map and then drag out a selection rectangle. Any contours or boresights that are caught in the rectangle will be selected. Alternatively just hold SHIFT and click to add or remove items from the selection.

Multiple selections have their own Selection Toolbar. If you have a combination of boresights and contours then you will only get options to Duplicate or Delete.

However, if your selection only contains contours then you’ll get all the options that are available to you when just a single contour is selected. This allows you make changes like smoothing or point reduction to several contours at once. You can also resize the selection when it only contains contours. All contours will size proportionally and maintain the same relative spacing from each another.

Copy and Paste

You can copy any selected contour or boresight, or any selected combination by using the standard keyboard shortcut CTRL+C. To paste the copied selection use the standard keyboard shortcut for paste, CTRL+V.

Display Options

There are several options for controlling the way that items are displayed. Click the Contour Colours button to choose one of eight built in colour schemes for displaying contours. Click on the map to finish.

When you are finished, click OK to return to the Antenna dialog.

You will now see your contours displayed in the preview window.

If you have the contour data in GIMS format, you can load this into the software by clicking the Load button. Contours can also be saved to this format.

Advanced Beam Options

• For all Beams

• Shaped Beams

• Contour Beams

• IMT-Model Non-Co-Frequency Parameters

For all Beams

For most purposes, you will only need to specify the gain pattern for a beam. However, in some circumstances you may need to specify default EIRP, frequency, noise and polarisation – this will depend on choices made in defining your Links and in most modelling situations, these parameters are specified directly in the Link and the Antenna parameters are ignored.

Example applications of Antenna Advanced parameters are for:

• Frequency re-use in multiple beam antennas
• To plot antenna footprints where no Link has been defined and a default frequency is needed
• To model simple variation in EIRP, as a random variable between a maximum and minimum value.

For traffic modelling you may need to define a maximum load parameter (see the Modules User Guide).

These parameters can be entered by clicking the ‘Advanced’ button.

The noise represents the temperature of the Antenna (sky noise, plus earth noise etc) and can be used in the Link as part of the calculation of system noise. It will only be used if you decide not to enter the system temperature directly into the Link. If you specify this parameter and intend to use it, you must also enter the feeder loss (in the Station dialog) and the receiver noise figure (in the Link).

If you intend to specify the system noise temperature for your Link, then you don’t need to bother with Antenna temperature.

Note that the traffic modelling options will not be displayed unless the traffic module is enabled.

Shaped Beams

For shaped beams, there is another set of advanced options.

These allow you to add additional gain tables depending on the angle from the sub-satellite point. This allows you to model adaptive Antennas (sticky beams) using data derived from detailed models of the Antenna.

The options appear below the options described above.

Set the number of tables using the spin control or click the “Load…” button to load the data from a TXT file (note: the format of this file is described in the Technical Annex).

To edit a table, select the table number using the spin control then type the Azimuth from the sub-satellite point in the box provided then click “Edit” to configure the table.

If the option “Use Azimuth and Elevation” is selected, then an Elevation value can be input for the table.

Contour Beams

There are additional parameters for contour beams which are shown under ‘Interpolation Options’.

The software calculates the gain from contours beams by interpolation. You can change the way in which the interpolation is performed by clicking the Advanced button.

You can change the calculation method and the way in which multiple boresights are weighted in this process.

IMT-Model Non-Co-Frequency Parameters

There are additional parameters under the advanced beam options dialog when using one of the IMT-Models gain patterns. These allow the gain pattern to be different between co-frequency and non-co-frequency scenarios.

The following options are available:

• Use co-frequency pattern: the M.2101 pattern is used with D/lambda = 0.5 for both co-frequency and non-co-frequency scenarios
• Single element pattern: the M.2101 single element pattern is used if the victim centre frequency is non-co-frequency
• Assume D/lambda = 0.46: in the M.2101 gain pattern a D/lambda of 0.46 is used rather than 0.5
• Variable D/lambda: it is assumed that at the centre frequency supplied the D/lambda = 0.5, and so for other frequencies the D is derived and fixed but the lambda varies depending upon the victim frequency

The definition of what constitutes “co-frequency” and what “non-co-frequency” for the IMT-MODEL gain pattern is set via:

• Centre Frequency: this is the centre frequency that the IMT-MODEL antenna has been tuned to
• Co-Frequency Bandwidth: this is the total bandwidth that is defined as being co-frequency in range:
  • Minimum = CentreFrequency – CoFrequencyBandwidth./2
  • Maximum = CentreFrequency + CoFrequencyBandwidth./2

Outside this frequency range the interference path is assumed to be non-co-frequency.

Note that to activate these non-co-frequency gain patterns it is necessary to configure the Interference Path as described in Interference Paths.

Multiple Beams

The properties dialog for multiple beam Antennas, where each beam can have different properties is shown below.

The dialog has multiple tabs. Each beam has its own tab. These tabs contain the same set of controls as a single beam Antenna.

The Arrangement tab is where the layout of the multi-beam structure is determined – here you:

• Define the azimuth and elevation of each beam relative to the antenna boresight,
• Give the orientation of each beam
• Preview the layout from three different perspectives.

Managing Beams

The beam tools, along the top right of the dialog, allow you to change the number of beams on your Antenna. There are buttons for adding, duplicating and deleting beams.

Here is how to add a beam:

Click the Add button: a pop-up menu will appear. There are options for selecting 1, 2, 3, 4 or more beams.

If you select More beams, you will be asked to say how many you want:

The new beams will appear as extra tabs on the dialog. If there is not enough space to display all the beams, as many beams as possible will be displayed. Two scroll buttons will appear allowing you to scroll through the tabs.

Arranging Beams

The Arrangement tab allows you to organise the beams within your Antenna. By this we mean pointing the beams relative to the mechanical boresight of the Antenna.

At the top of the arrangement tab is a table. This table allows you to set the pointing and the orientation for each beam. By default, all beams are pointed along the boresight of the Antenna. To change any of the entries in the table, simply click in the table and type a new value. You can paste in data if you have the information elsewhere.

The example below shows three beams. Each one is pointing in a different direction relative to the Antenna boresight.

There are three views – the top view (showing the azimuth of each beam), the side view (showing the elevation of each beam) and the boresight view (showing the 3dB contours of each beam viewed from the perspective of the Antenna).

You can choose whether you want the beam labels to be displayed in the preview windows. If more than one beam overlaps exactly in any of the windows, the label of the first beam is shown followed by two dots. This indicates that there is more than one beam represented at that location.

As well as entering the (azimuth, elevation) directly, you can also move the beam pointing by selecting a beam on one of the previews and moving it to a new location.

Beams can be designated as electronically steerable. If this option is selected the beams will be pointed by according to the Link set up. This means that you won’t have to specify any pointing information on the arrangement tab.

In this example, Beam 2 is steerable and so the pointing options are replaced with text that indicates this. In addition, the beam no longer has a pointing direction in the preview windows. Instead, steerable beams are shown in the bottom-right corner of each preview.

Modifying Beams

When you click in the Beam Pointing table on the Arrangement tab, the corresponding beam name is highlighted in the table. To help with identification, the beam is also highlighted in the preview windows and on the beam tab. If the tab for the beam is not visible it is scrolled into view.

To modify the parameters for a beam, you can either click on the beam tab or you can double click on the beam in one of the preview windows. If you use the double-click option and the beam tab is not visible, it will be scrolled into view and selected.

Editing of individual beam properties is exactly the same as for single beam Antennas. However, because this is a multiple beam Antenna, the individual beams can be duplicated and deleted.

Duplicating and Deleting Beams

When a beam has been selected, the duplicate and delete beam buttons become available. To duplicate a beam, click duplicate. A new copy of the beam will be created. The copy will become the selected beam. To create multiple copies, simply keep pressing the duplicate button until the desired number of beams has been created.

To delete the selected beam, click Delete.

Multiple Identical Beams

The Multiple Identical Beams option differs from the Multiple Beams option in that however many beams you create, there will be only one Beams parameter tab and this will be applied to all the beams.

Symmetric Spot Beam Pattern

Many popular satellite systems designs include multiple spot beams, arranged in symmetric patterns around the Antenna boresight. The regular arrangement of beams with circular, hexagonal or square symmetry is used to provide cellular coverage on the ground.

These can be created using the symmetric spot beam pattern antenna, as in the figure below.

Note that you will have to change the beam type from isotropic / omnidirectional to see the beams as circles.

This dialog allows complex arrangements of beams to be created using the various controls. After the standard field for the antenna name, the dialog is split into the following sections:

• Pattern
• Orientation of beams
• Configuration of beam layout
• Definition of beam(s)

Starting with the pattern, a number of configurations can be defined, including circular, hexagonal (either orientation) or square (with or without central beam).

Some examples are shown below.

Circular Pattern	Hexagonal Pattern	Square Pattern

If all the beams are circular, then it doesn’t matter how they are orientated. However, if they are elliptical it can make a significant difference – for example to maximise coverage or to reduce number of handovers between beams. Hence there are options to select the following three orientation options:

Long Axis Towards Sub-Satellite Point	Short Axis Towards Sub-Satellite point	Long Axis Aligned with Velocity Vector

A check box control on the dialog allows the orientation axis to be shown or hidden.

There are then controls to define the number and spacing of beams with the pattern, as in the figures below:

Hexagonal Pattern with 2 Rings of Spots	Hexagonal Pattern with 3 Rings of Spots	Hexagonal Pattern with 4 Rings of Spots

If you are using a hexagonal pattern to cover the field of view from a non-GSO satellite the outer beams are often not required as they would point towards space rather than intersect the Earth. Hence there is a trim or clip option to cut the outer beams at a specified angle, as in the examples below.

5 Ring Hexagonal Pattern without Clip	5 Ring Hexagonal Pattern with Clip

All the beams can use the same pattern, as in the examples above. If you want different beams to use different patterns, then you can create a set of beam types that can be assigned to each beam. To increment the number of beam types that can be used and to edit each one, use these controls:

These beam types can be assigned by clicking on one of the numbers to select it and then on each of the beams on the preview. This can be used (for example) to create frequency re-use patterns, as in the figure below.

Satellite PFD Mask

Visualyse Interplanetary can create a special type of Antenna that will reproduce the constraints of an elevation (or alpha angle) dependent PFD mask. To create a satellite PFD mask, select Satellite PFD mask from the Antenna types dialog: this will open the Antenna properties for the new PFD mask.

Satellite PFD masks are specified as arrays of maximum allowable PFD at defined elevation (or alpha) angles.

The PFD Mask can be modified to specify the PFD mask is used for RNSS calculations under Resolution 609 via the "PFD Mask for RNSS into ARNS studies" option.

To define the PFD mask using Alpha angle (for EPFD studies) check the "Alpha PFD Mask for EPFD studies option".

Note the prompts as to how to use the PFD mask e.g. that the reference bandwidth will be defined when this Antenna is associated with a Link via its Carrier.

Stations

• Creating Stations
• Station Types in Visualyse Interplanetary
• Antenna and Beam Pointing

Stations define the locations of your transmitters and receivers. They also define the dynamics i.e. how the scenario will evolve.

The Station object includes, by reference, one or more Antennas which the Station points using one of the eight pointing options.

Stations are an essential part of the definition of the geometry of a scenario. Later we will see how this geometry is completed and the topology defined by the addition of Link objects.

Creating Stations

The Station List can be accessed from the Model menu or from the toolbar. The list is shown below.

This list and its window can be filtered in two ways. First, it can be filtered on name.

Secondly you can filter the list by Station type.

To add a Station from this location, click the add button. This will display a Station type selection dialog.

By default, the software opens a new edit dialog as soon as you create a Station. You can switch off this option by unchecking the box in the bottom right of the List Dialog

Station Types in Visualyse Interplanetary

Visualyse Interplanetary has seven station types:

• Ground Station
• Fixed Station
• Mobile Station
• Maritime Station
• Aeronautical Station
• Stationary Satellite
• General Satellite

The difference between the various types relates to fundamental difference in their dynamics – e.g. fixed stations are constrained to move with a fixed point on the earth’s surface, Stationary satellites have a fixed longitude in the geostationary orbit etc.

Logically there is no distinction between an Ground Station (commonly taken to be a satellite ground station) and a fixed station – in fact some investigation will show that the only difference between the dialogs is in the default icon that is used.

It is recommended that you read Stations, which give information relevant to all station types.

The other subsections below give information specific to the station type you may wish to model.

Antenna and Beam Pointing

Common to all Station types is a selection of the method used to point the antennas.

Antennas can point in one of eight ways:

• Fixed pointing direction
• Point at another Station
• Rotate in the azimuth plane
• Scan between two azimuths
• Allow the Link to set pointing
• Point at another Station OR the common volume
• Track a station with fixed elevation
• Point at another station using random offsets
• Elevation by latitude

In addition, electronically steerable beams can have their pointing angles changed by Links.

These options are described below.

Note that all Antennas have their own position and velocity vectors based upon the position and velocity vectors of the containing Station, with offset for Antenna height if required.

Fixed Pointing Direction

In this case the user specifies the (azimuth, elevation), and these values are fixed for the duration of the run for the relevant beam or Antenna.

Point at Another Station

Fixed on Station can take one of the following as it’s tracking target as:

• Fixed upon a target Station
• Fixed upon a target Antenna

In each case at each time step the pointing angles of the Antenna are set up using the vector position and velocity of this Antenna and the vector position and velocity of the target Station/Antenna.

Rotate in the Azimuth Plane

Scanning Antennas have the following parameters defined:

• Elevation angle
• Start azimuth
• Scan rate in degrees / second

Scan between two azimuths

Scanning Antennas have the following parameters defined:

• Elevation angle
• Start azimuth
• End azimuth
• Scan rate in degrees / second

Allow the Link to Set Pointing

These Antennas have their pointing angles updated by a Link during Link update if the Antenna is used, otherwise the angles are not changed.

Point at Another Station or the Common Volume

In this case the Antenna will point in the direction (azimuth) of the selected Station, but that Station is (or becomes if the Station is moving) transhorizon, will point at the horizon in the direction. In effect this is how a troposcatter system points its Antennas.

The ‘common volume’ is indicated in the diagram below

Track a station with fixed elevation

This option is as “Point at Another Station” but the user can enter a fixed elevation value that is used at every time step instead of the calculated value.

Point at another station using random offsets

This option is as “Point at Another Station” but the user can enter a random offset range for azimuth and elevation that are used at every time step instead of the calculated value.

Elevation by latitude

A table of elevation angle vs. latitude should be entered together with the azimuth to use. At each time step the current latitude of the station will be used to derive an elevation angle from the table using linear interpolation. For non-GSO systems the coordinate reference system should be set to “North based”.

Note on Electronically Steerable Beams

If a beam is defined in the Antenna dialog as ‘Electronically Steerable’ the point angles can be defined by reference to a Link where the end point of a link moves, or is subject to handover, the point angles of the beam may change from whatever is defined in the Station.

Fixed Stations

When you create a new fixed Station, the dialog shown below will appear.

The Station icon can be changed by clicking on the small black arrow by the side of the icon. This produces a drop-down menu from which a new icon can be selected.

The tabs shown when this station is created are Position, Traffic and Advanced.

Position

The position tab allows you to set the location of the Station.

You can change the latitude and longitude of the Station. Clicking on the units will produce a popup menu from which you can pick the units that are appropriate.

If you select degrees, minutes, seconds, the format is:

[N/S/E/W] DD:MM’SS.SS”

You can choose whether to specify the height of your Station above the terrain or above sea level. If you have any terrain data in this simulation the terrain height at that location is displayed.

Adding and Managing Antennas

A Station can have multiple Antennas. The parameters for each Antenna are presented on a separate tab. By default, a Station is created with one Antenna.

An example Antenna tab is shown below.

The parameters for the selected Antenna are:

• Type – which of your library of antenna models to use for this station
• Feeder loss – what is the loss in dB due to the feed from the antenna to the receiver (not transmitter – see Technical Annex for more information)
• Pointing options – how is the pointing of this antenna determined.

Click the Select button to change the type of Antenna. This will show a dialog from which you can choose one of the new Antennas you have created.

Choosing an Antenna Type means that the Station will use the characteristics of the Antenna as defined in the Antenna list. An important point is that if the Antenna in the Antenna list changes, all Stations that use that Antenna will change accordingly.

Antenna Pointing

They presented as a set of radio buttons and the options are described in Antenna and Beam Pointing. Clicking the required method reveals the parameters needed to fully define it.

First you decide how you want to point your Antenna, and then you set the required parameters for the pointing option you have chosen.

More options

The ‘more options’ button allows you to specify Antenna temperature and the Antenna height.

Feeder temperature is needed if you are going to let Visualyse Interplanetary calculate system noise from the component contributions due to the Antenna, feeder and receiver. The choice of how to calculate system noise is made in the Link dialog – you have the option simply to enter the system noise directly in Kelvins, and if you are going to do this there is no need to enter the Antenna noise.

Antenna height is the height above the Station, and has some influence on some propagation models and, of course some influence on the simulation geometry.

Managing Multiple Antennas in a Single Station

Management of multiple antennas is very similar to that of beams on the Antenna dialog (Managing Beams). To add multiple Antennas, click on the black arrow to the right of the Add Antennas button.

From this menu, you can choose how many Antennas you want to add to your Station. There are options for quickly adding up to four Antennas at a time. If you want more than four Antennas, click the More Antennas option. A dialog box will appear allowing you to specify the exact number of Antennas you require.

New Antennas appear as new tabs. If there are more Antennas than will fit across the dialog, scroll buttons will appear to allow you to access the extra tabs.

Duplicating and deleting functions work on the currently selected Antenna. If you duplicate, the new Antenna becomes the active selection. If you delete, the next Antenna becomes the selection (unless you delete the last Antenna in which case the previous Antenna becomes the active selection)

Naming Antennas

Antennas are automatically given names by the software. However, you can give your Antennas more meaningful names, and this practise is encouraged because good naming makes complex models easier to understand (especially if you revisit them at some time in the future and need to remember what you were doing)

You rename the antenna by interacting with the name on the tab directly. It works in the same way as when you change the Station name.

When the mouse passes over the Antenna name the cursor changes to a caret,

If you click on the name, it changes to an edit box so that you can alter it. This is shown below.

Typing a new name causes the tab to automatically resize. Click away or hit Return to finish editing.

You can only do this with the selected Antenna. To change the name of another Antenna, you need to select it first.

Advanced Option

The advanced tab incorporates the Station coordinate system parameters and attitude parameters relating to the station reference frame.

For a description of the effect of changing the coordinate system reference, and for definitions of the Station azimuth and elevation see the Technical Annex.

Traffic Modelling

Traffic won’t appear on the Station dialog at all unless your installation has the traffic module. If traffic is enabled, the traffic tab will appear as shown below.

For details of how to use the traffic module, please refer to the Module User Guide. Note the maximum load field can be used by the Population Data processing as described in Service Area Wizard.

Ground Station

These are identical to Fixed Stations in terms of functionality. The only difference is the dialog name and the default icon (an Earth Station).

Mobile Stations

Mobile Stations are the same as Fixed Stations except that they can move around. The position tab allows you to set the start location and how the Station moves from that start location.

Heading can be changed by typing a value in the box. The angle control next to the box indicates the angle that has been entered. By clicking and dragging in the angle control itself, you can also set the heading.

Note: that this simple motion can be over-ridden by using the Define Variable module, which allows you complete control over the location of the station throughout a simulation. This module also allows you to vary parameters randomly and hence perform Monte-Carlo simulations (see the Modules User Guide)

Maritime

These are the same as mobile stations. The only difference is the default icon (a ship).

Aeronautical

Again, identical to mobile stations, but with the addition of a climb rate parameter on the Position tab. Default icon is an aircraft.

General Satellites

Satellites differ from fixed and mobile Stations only by the way their position is specified. For General satellites, the classical orbit elements describe an orbital pattern that allows the position of the satellite to be calculated for any point in time.

So instead of the position page on the Station dialog, for General satellites, we have the Orbit page.

This dialog prompts you for a set of parameters that define the orbital elements of a satellite.

There are two modelling options here:

• Selection of the orbit model
• Selection of way to define the ascending node.

Visualyse Interplanetary has two orbit propagation options:

• Simple central potential
• Central potential plus secular perturbations due to the J2 term associated with asphericity of the earth.

For technical details you can refer to the Technical Annex.

The ascending node can be specified relative to a fixed location on the earth (longitude) or a fixed location in space (first point of Aries). The first option is called ‘Longitude of Ascending Node’ the second is ‘Right Ascension’

Choosing right ascension now requires you to specify an epoch for the orbit. This is needed as the location of a satellite will change relative to the earth if the time at which the orbital elements were valid is different from the current simulation time.

So, for example, you may have an element data from a couple of weeks ago but only just be ready to make your simulation. In this case you need to tell Visualyse Interplanetary has two orbit propagation options: the date on which the orbit data were valid (the Epoch).

The Epoch definition is accessed via the Advanced button on this dialog

Stationary Satellites

Stationary satellites are in orbit just like the non-GSOs. However, because they maintain a roughly fixed position above the earth, we don’t need to define them by the classical orbit elements and can specify their position in a simpler way.

For most Stationary satellite work, only the longitude and inclination angle are required. For more advanced modelling, click the “More orbital elements” button. This will open the GSO orbital elements dialog. This allows you to specify the eccentricity, and phase in e and i.

Phase in e (eccentricity) and Phase in i (inclination) relate to orbital anomaly (see the Technical Annex). Phase in e tells you how far from the apogee the satellite is at and Phase in i how far it is from maximum inclination – when the satellite was created. These parameters can have a dramatic effect on the ground track of satellite that is not in exactly circular orbit.

Station Groups

Station Groups are introduced in Visualyse Interplanetary Interplanetary to make large simulations more manageable and understandable.

They also have associated ‘Wizards’ that allow for simpler creation of multiple identical stations based on a few parameters – for example you can make large constellations of identical satellites, or thousands of test point stations in defined service area.

As a general tip, it is better to manage Stations through Groups rather than directly through the Station List. The Station List can become very large, even in relatively simple scenarios

Stations in Visualyse Interplanetary can be collected into Groups. Stations in a Group may or may not be connected for interference calculation purposes. Groups can be used simply as aids to organising and analysing data.

A Station can be in more than one Group at the same time. Station Groups are treated as subsets of the complete Station List.

Visualyse Interplanetary includes four methods for creating Station Groups, each of which is now briefly discussed. Detailed descriptions of each type are given in the subsequent sections.

Station Group - Create Empty

Empty groups can be created and Stations can be added to it from the list of all Stations within the simulation. Even if Stations are being created individually it can be useful to assign them to a Group – for example to manage simulations by collecting like Stations together.

This also allows groupings of Stations that are not related in any of the ways assumed by the other Groups.

For example, satellite constellations that do not have the symmetries assumed by the Constellation Wizard are not excluded in Visualyse Interplanetary. The Constellation Wizard can be run several times to produce single planes of satellites with differing orbital parameters. Then, by creating and editing an empty Group it is possible to put all the planes into the same group and create a new constellation.

Mixed GSO/nonGSO constellations can be created in a similar way.

Constellation Wizard

The Constellation Wizard creates a Group of identical Stations in a nonGSO constellation with certain symmetry properties. Stations are assumed to orbit in equally spaced planes and to be equally spaced around each plane. You can also use the Constellation Wizard to import two-line element sets (TLEs).

Service Area Wizard

The Service Area Wizard creates multiple Stations in or on the boundary of a geographical area defined by latitude/longitude limits, or by the footprint of a selected antenna

HEO Wizard

The HEO Wizard allows you to define constellations of HEO satellites in several useful orbit configurations.

Re-running the Wizards

In certain circumstances Wizards can be re-run in order to modify the Station Group. You need to be aware of the knock-on effect that this can gave on the rest of your simulation. The first thing that re-running a Station Wizard does is delete the existing station in the group to be re-defined – and this results in any Links that use those stations becoming un-defined. You will need to fix the affected links.

The Constellation Wizard

Selecting Constellation Wizard starts the wizard dialog. The Dialog consists of a single sheet as shown below.

A non-GSO constellation is defined in the wizard either by a set of parameters which you input directly or by pointing to a data file that contains TLEs.

If you select Define Constellation by ‘Symmetric Planes you will need to enter the parameters as described below:

• Number of planes of satellites
• Number of satellites per plane
• Orbit height (altitude) - given in kilometres above mean sea level
• Orbit inclination - given in degrees
• Angle between planes – this is difference in latitude between adjacent satellite planes. You can set this to any angle or ask Visualyse Interplanetary to space the planes evenly.
• Phasing between consecutive planes – this specifies whether there is any relative offset in anomaly between equivalent satellites in adjacent planes
• The longitude of the ascending node of the first plane (at t=0)
• The offset of the first satellite in the first plane (specifies the anomaly of the first satellite in plane one at t= 0)
• The artificial precession rate.

The preview facility shows the sub-satellite points of all the satellites in the constellation and can be used to fine tune the coverage.

For many larger constellations, the phase between satellites in different planes is not controlled and can be modelled as essentially random. The Constellation Wizard provides a facility to randomise the phase. To use this feature, select the ‘Random’ box. To see the effect of the random phasing, click the Randomise button, followed by the preview button.

To make even randomly generated results repeatable, the Randomise button will always use the same sequence of pseudorandom numbers. To get n different random phasings, click the randomise button 1, 2, 3, … n times.

Constellations Based on Two Line Elements

If you choose “Define Constellation by” to be “TLE File”, you will see the dialog below:

To import data click the ‘Import TLE button’ and locate the text file containing the elements.

You will be presented with a list of all satellites in the file, which may look something like the following

You must either select each satellite you want to import individually or click ‘Choose all systems’. When you have made you choice, a preview will appear and when you are ready to go, click the Create button bottom right of the dialog..

Template Satellite Parameters

As well as Constellation parameters, you will need to define the satellite parameters that will be used for each satellite (you define one set of parameters and all satellites are identical on creation).

To define your template satellite, click on the ‘Satellite Properties’ button. This will bring up the non-GSO Satellite dialog. The orbit tab can be ignored, as this will be over-ridden by the constellation dynamics.

Set up the Antenna for your template satellite and the Wizard will create a constellation of identical satellites for you.

Service Area Wizard

Service Area analysis, looking at detailed results over a wide area, can be performed by distributing test point Stations over an extended area and setting up Links to each Station. Useful information about service levels can then be obtained by analysing the Links to find ‘worst cases’ (see Link Groups for more details).

The Service Area Wizard has three pages. The first page is the Template Station page (shown below).

You can set the name of the Service Area Group in the top-left of the dialog. The station icon can also be changed.

The other options allow you to say which station will be replicated across the service area. The choices are:

• Use an existing Station as a template – you will then need to select the Station to use from the list box
• Define a new template Station: pressing the Edit button allows you to define the new station which will be used as the template

Having made the selection and defined your template Station, click Next to move on to the Service Area page. From here you can define the extent of your service area.

There are five ways you can define your service area:

• As a rectangular region
• By reference to a particular Beam footprint
• Using a Country border derived from the IDWM database
• Based on a series of discrete points defined in a text file
• Using a hexagonal deployment

Service Area Defined by Region

If you want to define it by a rectangular region, select the Region option. This is the default and is shown below.

The extent of the area is shown, and you can edit the latitude and longitude of the corners directly at the top of the dialog. The area is also shown on the map as a shaded red border. You can resize and move this border to change the size of the service area.

You can zoom into the map by clicking the magnifying glass. This puts you into zoom mode. When you pass the mouse over the map the pointer will change to a magnifying glass - left-click to zoom in and right-click to zoom out. You can move around by dragging the map as you move around on the Plate Carrée or Mercator views.

When you have selected the geographic extent of your area you then need to decide whether to fill the area or populate its edges. If the former, then it is necessary to specify:

• How many stations will fill it.
• How will those stations be deployed.

You must choose between three methods for defining your grid:

1. Stations: in that case you simply say how many columns of stations there will be (‘North’) and how many rows (‘East’). Visualyse Interplanetary will create a rectangular grid based on this input
2. Grid: this also creates a rectangular grid, but this time based on the spacing of stations N-S and E-W.
3. Hexagon: in this case the grid is in a hexagonal not rectangular pattern, again based upon spacing of stations N-S and E-W.

If rather than filling the area you want to fill the perimeter you must defined the spacing between Stations.

If “Get population data” is selected, then each of the Stations created will have their “Maximum load” field set from the population database. The population will be that calculated to be in a tile defined using the number of stations North/East or spacing in km North/East. Note that this option is not available when deploying stations in hexagons or with the fill the perimeter option. This requires the population data directory be set as in Population Data Settings

The preview window shows where stations will be located on a map. This is automatically updated whenever you change any of the parameters.

Service Area Defined by Beam

The second way of specifying an area is by a beam footprint. To do this, select the Beam Footprint option.

Select the satellite, antenna and beam you want to use, as shown in the figure below.

As with the region option, you can zoom into the map if you need to.

When you are happy with your service area, click Next. This will take you to the Station Deployment page. From here you decide how stations will be arranged in the service area.

There fill options are the same as for the region option described above.

Service Area Defined by Country

The next way of specifying an area is by using a country’s border. To do this, select the “Country” option and then from the drop-down list select the one of interest, as in the figure below:

Having done the selected country will be highlighted in the preview which you can configure using the standard zoom and map move options.

If you click on next you will be able to use the standard Service Area Wizard controls to either populate either the country’s area or border with Stations.

An example of the fill border options is shown in the figure below.

Service Area Defined by Locations

The next way of specifying an area is by using a text file to specify the (latitude, longitudes) of each station. To do this, select the “Location” option and then the file that contains the data, as in the figure below.

Having selected the appropriate file you can click next, and the wizard will display the latitude ad longitudes read in together with a preview on a map as in the figure below.

Service Area Defined by Hexagons

The final way to define the service area is through a deployment of stations in hexagonal pattern. To do this, select the “Hexagons” option and you will be prompted for the central latitude and longitude, e.g.

Again, the standard map zoom and pan controls can be used. If you click on “Next” you can then define the hexagonal pattern to use based upon rings or grid, as in the figures below.

A key field to both is the separation distance between Stations.

HEO Wizard

The Interplanetary HEO Wizard helps you define repeating ground track HEO constellations with varying numbers of ground track, orbit period and numbers of satellites per track.

The orbits that Interplanetary defines are also sometimes referred to as QuasiGEO, Molniya or Tundra orbits.

Each satellite is, as usual, based on a single template station.

The HEO Wizard Dialog is shown below:

The parameters that are used to define the HEO constellation are:

1. The period of the orbit
2. The number of distinct ground track s
3. The number of satellites per track
4. The eccentricity of the orbit
5. The orbital inclination angle
6. The apogee location – the highest point of the orbit. The satellites move more slowly at higher altitude and so the apogee point is the location where they are often said to be QuasiGSO. For a system that will provide service to the Northern Hemisphere the apogee would be in the north.
7. The longitude of the apogee of the first track – this defines the point on the earth above which the apogee will occur
8. Time between satellites on adjacent track reaching their apogee. This parameter determines whether, in a multi-track system, satellites on adjacent plane are interleaved or whether they are at the same relative points in their orbits at the same time.

Having defined all these parameters Interplanetary will create satellites with orbital elements that produce a single ground track for each plane – these elements are consistent with the point mass orbit propagation model.

Editing Groups

On the Model menu, select Station Groups. Select the Station Group you want to edit and click Edit. The Modify Group dialog (shown below) will be displayed.

The dialog contains two lists - the Station List and a list of Stations in the currently selected Group. Options from this dialog are as follows:

• Add - creates a new Station
• Wizard - run the wizard (for groups created by a wizard)
• Include - includes a Station from the Station List on the left in the Group
• Edit - edits the selected Station
• Duplicate - makes a new Station which is an exact copy of the selected Station
• Remove - removes the selected Station from the group
• Delete - deletes the selected Station from the simulation
• Filter – filters the Station List on the left

Re-running Station Group Wizards

In most circumstances you can re-run a Station Wizard to modify the parameters of the Station Group. However, usually there are knock-on effects to other parts of the simulation, and you need to be aware of these.

The first thing that the Wizard does, if you re-run it, is to delete all the Stations currently in the Group. If you have already included those Stations in Link objects, then those Link objects will be affected and will need to be repaired.

In many cases, you will have Linked the Stations up using a Link Group Wizard, and you will be able to re-run the Link Group Wizard to fix up the Links.

Importing GSO and Non-GSO Satellite System

The first two options will allow you to import station information from the SRS database.

You need to have a compatible installation of the SRS and the GIMS database – Refdb.

To use the Import GSO facility you need to define the location of the SRS database.

Clicking the Import GSO button or selecting Import GSO from the Model Menu, opens the GSO Systems Chooser dialog – the first part of which is shown below. If this is the first time you have used this feature you will need to click on the button ‘Click here to select a data source’.

Once the database is loaded, the list of available stations will be populated.

You can apply a number of filters to the list:

1. Filter by name
2. Filter by frequency – show only networks with notified frequencies in the range specified
3. Filter by longitude – show only networks with the specified longitude range
4. Filter by Admin code – show only networks of a selected administration.

The network list will be adjusted according to the filters you set, and you can then select the network(s) you wish to import.

Some networks are shown in grey and some in black. Grey networks are API notices and have no antenna data associated. In these cases, the import will only give you an empty GSO Station object.

For networks in black bold text, Visualyse Interplanetary will retrieve all the antenna data from the GIMS database and create a Station object and an Antenna object representing each network.

For non-GSO systems, the process runs along similar lines. Clicking the Import non-GSO button or selecting Import non-GSO from the Model Menu, opens the non-GSO Systems Chooser dialog

The filters are simpler because the longitude filter does not apply but you can filter by name and admin.

To define your template satellite, click on the ‘Satellite Properties’ button. This will bring up the non-GSO Satellite dialog. The orbit tab can be ignored, as this will be over-ridden by the constellation dynamics.

Set up the Antenna for your template satellite and the Wizard will create a constellation of identical satellites for you.

When you import a non-GSO system you get a Station Group that represents the constellation in the filing.

Import FS Systems

You can import large numbers of fixed service microwave links using the FS import facility.

Choose Import FS Systems from the Model menu to access this function of the software. Systems can be imported from text file. You can copy and paste data from other applications or enter the data directly into the software.

The figure above shows you the format required – full details are given in the Technical Annex.

Once your preview data seems to be correct, click the ‘Create Systems’ button and Interplanetary creates multiple Station and Link objects which it places in Station and Link Groups.

Import from the Terrestrial IFIC

This feature interfaces directly to any database that has the structure of the Terrestrial IFIC.

Selecting the Import Terrestrial IFIC from the Model menu or clicking the terrestrial IFIC icon, starts up the dialog.

As for the other Import options, the first step is to define the location of your database. The database can be either a single .MDB file downloaded from the ITU website (BR IFIC option) or the collection of database files found on the Terrestrial IFIC DVD (DVD option).

Once this is defined there are number of filter options, which can be applied in combination:

1. Administration - import only filings from the specified administration

2. Receipt date - set a range of ‘receipt dates’ and only import systems filed within that range

3. Location - defined a box by latitude and longitude extremes and only import systems within that area

4. Filing type - import only systems of one or more given filing types

5. Service - import only systems of one or more given service types

   Having selected the search criteria and clicked on “Search”, Visualyse Interplanetary will search the Terrestrial IFIC for filings that meet the criteria.

   Note that searches with very wide criteria can take a long time to complete – it is recommended to use filtering where ever feasible.

   Having searched the IFIC, Visualyse Interplanetary will count the number of records and display them in a dialog similar to this:

This stage allows you to assess if the number returned is as expected – for example the criteria might too stringent and no systems were found or too wide so that thousands of systems would be imported.

If you are happy with the results click on “Yes” and then Visualyse Interplanetary will load a list of the systems that can then be selected. In addition it checks for duplicate filings – those that have the same parameters apart from one field that Visualyse Interplanetary would not use. For example the same system could be filed for two different reasons, but only one record would be returned.

This list would look something like this:

Sometimes the software is unable to load a system due to missing data. Clicking on the “xx Failed” text shows a dialog detailing why the systems failed to load the system.

You can then select all systems or a sub-set of the systems to import into Visualyse Interplanetary.

The Terrestrial IFIC import reads the database and populates the following objects:

• Antennas
• Stations
• Carriers
• Links

The figure below shows an example import and the model view is open to show all the objects created.

Tip: It is worth checking the data returned as there can be fields not defined. For example, in this example two of the stations had antenna height of zero metres – only one had a valid height.

Import Tx Systems

You can import large numbers of Transmit links using the Import Tx Systems facility.

Choose Import Tx Systems from the Model menu to access this function of the software. Systems can be imported from text file. You can copy and paste data from other applications or enter the data directly into the software.

The figure above shows you the format required – full details are given in the Technical Annex.

Once your preview data seems to be correct, click the ‘Create Systems’ button and Interplanetary creates multiple Station and Link objects which it places in Station and Link Groups.

Import Rx Systems

You can import large numbers of Receive links using the Import Rx Systems facility.

Choose Import Rx Systems from the Model menu to access this function of the software. Systems can be imported from text file. You can copy and paste data from other applications or enter the data directly into the software.

The figure above shows you the format required – full details are given in the Technical Annex.

Once your preview data seems to be correct, click the ‘Create Systems’ button and Interplanetary creates multiple Station and Link objects which it places in Station and Link Groups.

Import Non-GSO Orbit Elements

You can import large numbers of Non-GSO satellites using the Import Non-GSO Orbit Elements facility.

Choose Import Non-GSO Orbit Elements from the Model menu to access this function of the software. Systems can be imported from text file. You can copy and paste data from other applications or enter the data directly into the software.

The figure above shows you the format required – full details are given in the Technical Annex.

Once your preview data seems to be correct, click the ‘Create Systems’ button and Interplanetary creates multiple Station objects which it places in a Station Group.# Import Non-GSO Orbit Elements

Carriers

This section describes how carriers are modelled and defined in Visualyse Interplanetary.

Carriers are where you define bandwidths, polarisation, and other characteristics of the signal spectrum together with some aspects of the signal structure.

Things which are addressed in the carrier dialog are:

• Allocated bandwidth
• Occupied bandwidth
• Polarisation
• Receive and transmit masks
• Digital/analogue modulation
• Is the carrier a radar carrier
• Radar carrier parameters

The edit Carrier dialog is shown in the figure below.

The dialog is made more complex by the fact that the effect of bandwidths and spectral masks varies depending on choices you will make later when you set up the interference. Put simply – you need to decide how to deal with interference in cases where bandwidths can be very different and also how to deal with the out of band emissions implied by non-trivial spectral masks. This is covered further in more on this in Interference Paths.

Spectrum Masks and Net Filter Discrimination

Version 7 introduced the TX and RX masks which together can be used to define a net filter discrimination (NFD). The details of the calculation are given in the Technical Annex, but the idea is that you define the data that represents the spectral mask for in band and out of band emission/response for this carrier when used in a transmitter or receiver.

Data are entered in a table that gives the relative level of the mask compared to the peak, at any number of frequency off-sets from the centre frequency.

Later, when you define a victim and an interferer, Visualyse Interplanetary will do a numerical convolution and work out the Net Filter Discrimination over the whole overlapping band. You can also get Visualyse Interplanetary to use the bandwidth calculated from the transmit spectrum mask in the NFD calculations.

The carrier type can be specified as digital or analogue – if you are modelling multiple hop systems and looking at end-to-end performance this will have a significant effect. Noise on a series of analogue links is additive, whereas on digital regenerating links the noise in the system is determined by the worst single link.

The polarisation of the carrier can be defined as left or right circular, linear vertical or linear horizontal. This can be considered when calculating interference levels depending on choice made in setting up the Interference Path object (Interference Paths).

If you have the Visualyse Interplanetary Traffic Module then other carrier parameters, accessible via the Advanced button, will also be relevant. The significance of these parameters and the use of different load methods are described in the Module User Guide.

The radar parameters are used in the interference path to calculate the On Tune Rejection (OTR) according to ITU-R Rec. M.1461 “Procedures for determining the potential for interference between radars operating in the radiodetermination service and systems in other services”.

Propagation Modelling

Propagation modelling in Visualyse Interplanetary is dealt with at simulation level. This means you define a global propagation environment in terms of which loss models to apply to different types of Link, and Visualyse Interplanetary does the rest. The global environment can be over-ridden for each link individually.

Visualyse Interplanetary classifies Links into the following types:

• Terrestrial fixed
• Terrestrial mobile
• Space earth
• Space – space
• Broadcasting
• User defined (as many additional ones as you need)

For each Link type you define a set of propagation models to be applied. Different models to can be applied depending on whether the Link is victim or interferer.

We refer to the whole set of propagation models for the different Link types as the Propagation Environment.

In order the set your propagation environment begin with the Propagation menu (shown below).

To change the models used by a particular Link type, simply select the Link type from the Propagation menu. The properties dialog for the selection will be displayed.

The dialog above shows the models that will be used for terrestrial fixed Links.

You may wish to treat propagation in a different way when considering wanted and interfering signal levels – this is normal practise if you are following ITU-R Recommendations. In Visualyse Interplanetary, a Link can be used as both a victim and interferer.

You can change the models used by clicking the appropriate ‘Change Models’ button. The Propagation models dialog will appear.

You can select any combination of the base propagation models plus any rain or atmospheric models. Visualyse Interplanetary does not restrict the combinations you choose but will generate a warning message (which you can ignore) if you choose two models, each of which has a free space element included in it. This helps prevent double counting of free space loss.

Propagation Model Parameters

Many of the propagation models have associated parameters. You can edit these by double clicking on the model or by selecting it and clicking the Model Parameters button. This will show the propagation parameter dialog for the model. An example is shown below.

A description of the available propagation models is given in the Technical Annex.

Creating Your Own Propagation Link Types

You can create your own propagation Link types – an example application might be if you are modelling a mobile system with go and return links on widely different frequencies. In this case you may want to have ‘UHF Mobile’ and ‘VHF Mobile’ modelled as different Link Types.

To do this, select Advanced from the Propagation menu. The custom propagation Link types dialog will appear.

Click Add to add a new Propagation Link type. The edit dialog for the new Link type will appear. This is the same as the dialog for built in Link types, except that there is a field for the name at the top of the dialog.

Make your changes and click ok. You will be returned to the previous dialog. Click Close and then click the Propagation menu again. You will see your new propagation Link type under the built in Link types.

The Technical Annex contains a tutorial on propagation which is a useful introduction for the non-specialist on the selection and use of propagation models for interference analysis.

Links

Link objects are used in Visualyse Interplanetary to:

• Connect Stations together
• Define parameters related to the propagation of radio waves
• Set the criteria by which interference levels are judged

The Link is where Stations, Carriers, frequencies, propagation models, interference criteria and interference statistics gathering are combined to define a communications path.

The Links Dialog

The Links Dialog can be invoked in the normal ways, i.e.

• Via the toolbar icons
• Via the Model menu
• By right mouse click in the Model View

There are four types of Link that you can create, depending on what you want to do.

A Fixed Link has explicitly defined start and end Stations, which do not change during the simulation, but which are not necessarily fixed Stations. Many modelling scenarios call for the use of fixed links.

A Receive Link has an explicitly defined end Station, but no defined start Station. This type of Link could be used for earth observation satellites for example, or in any case where a fixed receive signal is known.

A Transmit Link has an explicitly defined start Station (or Group of Stations) but no defined end Station. This type of Link would be used for a broadcast system being considered only as an interferer. Receive Stations are not relevant to the scenario and can therefore be omitted.

The ‘source’ of a transmit Link multiple Stations, multiple beams and multiple Antennas. So, for example, if you have a Group of two Stations each with two Antennas which themselves have two beams there are various ways of specifying a transmit Link:

• Both Stations transmitting through both their Antennas using all beams, or:
• One Station transmitting through both Antennas using both beams, or:
• One Station transmitting through one Antenna using both beams, or:
• One Station transmitting through one Antenna using one beam.

In a Dynamic Link the start and/or end Station, are selected from a group according to one of several criteria that may vary through the simulation. For example, in the case of a nonGSO satellite constellation, the feeder Link Earth Stations will experience handover from satellite to satellite that will be dependent on elevation angle. This would be modelled as a Dynamic Link in Visualyse Interplanetary.

Fixed and Dynamic Links contain two Link Paths, one for the forward communication direction and one for the return direction. Forward and return directions are defined in relation to the start and end Stations, the forward path always running from the start Station to the end Station. Each direction can have separately defined powers and criteria.

A Receive Link has a single Link Path into the receive while a transmit Link has no Link Paths at all.

All Link dialogs have an option to change how Links are shown on the map and 3D views. This is done via a combination of the ‘Display’ button in the Link dialog and the Link display method in the configure option of the view menu.

The Link dialog also defines the powers, propagation characteristics and the interference criteria levels for the Links.

The dialog is in the form of tabbed sheets. Each tab is described in detail below. Tabs that are common to more than one Link type are described first.

Fixed Link

The dialog has five tabs (six if you have the Traffic Module enabled).

The first two tabs define the start and end points of the Link. The next two define the parameters associate with the link in the both directions, and the final tab is labelled ‘Advanced’.

Start & End Stations

The Start Tab of the Fixed Link dialog is shown below.

Select a Station to define the starting point of the Link from the drop-down list. If any Stations appear in Groups, the Groups will be shown, and you can expand each Group to show the Stations it contains.

If the selected Station has multiple Antennas or Beams, you will need to select from these as well.

The end station tab is the same as the start station tab except for the antenna and beam labelling.

Link Paths

Each Link can have two associated Link Paths. These are associated with two possible directions of communications for each Link, allowing you for example to model up links and down links without too much input data duplication. The Link Paths are called:

• Start to End – in the direction start station to end station
• End to Start – in the direction end station to start station

The StartEnd tab is shown below.

End to start and start to end tabs work in exactly the same way.

You can specify whether the link path is enabled or not using the check box at the top of the tab.

Frequency and Bandwidth of the Link

On each active Link Path you must select a Carrier (which defines the bandwidth) and a centre frequency.

Transmitter

For the start to end link path, this will be the start station. The main feature of the transmitter is its power. Power is made more compact by allowing you to say how you want to specify it before asking you for the relevant parameters. You can choose from the following options:

• Fixed power level: the power level is a fixed value
• Adaptive power control: the power level changes to achieve a target receive level
• PFD power control: the power level changes to achieve a target PFD
• Bandwidth control: the bandwidth changes rather than the transmit power
• Constant receive power : the receive level is fixed
• Random (specify limits) : power is random between some user defined limits
• Random (limits from antenna): power is random between the limits defined in the antenna
• Fixed amplification: the transmit power is the receive signal of the previous link plus a constant
• Table amplification: the transmit power is the receive signal of the previous link plus and an amplification factor that depends upon the receive signal

For the return direction (EndStart) there are two additional power options:

• Radar reflection
• Listen before transmit

More information on how to use these two options is given in the Technical Annex.

A detailed description of all the options is given in the Technical Note: Transmit Power Options

Tip: Note that the transmit power is referenced at the input to the antenna. See the Technical Annex for more information about link reference points.

Receiver

For the start to end link path, the end station is a receiver.

The main feature of the receiver is the specification of system noise. This is shown diagrammatically in the bottom right of the dialog.

If the calculate system noise option is selected, the software will compute the system noise from the temperatures and losses at the antenna and feeder you have already provided in the Antenna and Station dialogs. These contributions are shown on the diagram. The receiver noise figure must be provided to complete the calculation.

If the noise is not being calculated, the diagram is greyed out and a box is provided for the system noise figure.

Note that the reference point is immediately after the antenna feed. The feeder loss is specified in the Station dialog (see Adding and Managing Antennas) for each Antenna. If you want to do your calculations at a reference point immediately after the antenna you should put zero in the for the feeder loss and specify the system noise directly.

If you have a rain model switched on (see Propagation Modelling) you can optionally include the increase in noise on a Link due to scattering by rain.

Advanced Options

The advanced tab allows you to override the propagation and statistics that are specified at simulation level. You can also set the link colour. This is shown below.

If you decide to override the default propagation models, click the Propagation models button. This will display the propagation options dialog.

The default models for the link type will be displayed. Click “Change Models” to change the models that are used for this link. Double-click on a model or select it and click “Edit Parameters” to change the default parameters used for that model.

The statistics options work in the same way.

Traffic

As with Stations, the Traffic tab will not be shown unless the traffic module is enabled. If traffic is enabled, an extra tab called Traffic will appear.

You can decide whether to enable traffic modelling on the link and if so what traffic model to use. The Traffic modelling option is explained in the Module User Guide.

Receive Link

Receive links have no transmitting capabilities. They are used to set up receivers to use as test points for interference measurement. They are the simplest of all the links consisting of a single station and some receiver characteristics.

End tab

The End Tab defines the station, antenna and beam which will form the end point of this receive link. Receive antenna and Receive beam choices only need to be made when the selected station has multiple antennas and multiple beams.

Receive tab

The Receive tab is where the Link parameters are defined: it is shown in the figure below.

In this dialog you will need to:

1. Select a Carrier and a frequency
2. Define a nominal received level (note, only needed if you want to work with C/I or C/(N+I) criteria
3. Define the link noise as per the Fixed Link dialog.

If the calculate system noise option is selected, the software will compute the system noise from the temperatures and losses at the antenna and feeder you have already provided in the Antenna and Station dialogs. These contributions are shown on the diagram. The receiver noise figure must be provided to complete the calculation.

If the noise is not being calculated, the diagram is greyed out and a box is provided for the system noise figure.

Note that the reference point is immediately after the antenna feed. The feeder loss is specified in the Station dialog (see Adding and Managing Antennas) for each Antenna. If you want to do your calculations at a reference point immediately after the antenna you should put zero in the for the feeder loss and specify the system noise directly.

If you have a rain model switched on (see Propagation Modelling) you can optionally include the increase in noise on a Link due to scattering by rain.

Transmit Link

A Transmit link contains only start Station(s). You can consider these simply as sources of interference and use them when you are not interested in the other end of the Link.

It contains a tab defining the Start Station, Antenna and Beam.

One important feature of a Transmit link is that the source can be defined as multiple beams, on multiple antennas and even multiple stations. In the Transmit link, you just switch on all stations and the interference is aggregated.

A tab called Transmit and the Advanced Tab as per the Fixed Link dialog

The Transmit Tab is shown below:

On this tab you need to define:

1. The carrier – selected from a drop-down list of existing carriers
2. The frequency – and whether you will use the antenna default frequency or a fixed value. This point is subtle, but if you have multiple sources in your transmit link, you can implement a sort of frequency re-use pattern by using a different antenna, with different default frequency, for each source.
3. What is the power level and whether this is fixed or taken from the antenna defaults.

Dynamic Link

These differ from fixed links by the fact that the start and end stations can change as the simulation runs.

The start end, end start, Traffic and Advanced tabs are therefore the same as for Fixed Links. The only differences are the start and end station tabs.

Start Station

The start station tab is shown below.

Two options are provided for the selection of start station use a named station (just like a fixed link) and use the end station of another link. The second option allows you to chain together Dynamic Links and therefore model, for example, the inter-satellite links in a non-GSO constellation.

You must also select the Antenna and Beam to start the Link on. Select either a named Antenna and Beam or pick any Antenna/Beam combination capable of tracking the end station. If you take the second option, Visualyse Interplanetary will manage the available resources and select the first available antenna.

Select either ‘Any tracking antenna’ or an antenna from the list.

Beam selection is a little more complex. The options are shown below.

Beam selection options are:

• Any tracking beam – Visualyse Interplanetary will choose the first available steerable beam
• Highest gain beam – Visualyse Interplanetary will choose a beam from the selected antenna that has the highest gain
• Nearest beam – Visualyse Interplanetary will choose a beam from the selected antenna, whose boresight latitude and longitude are closest to the location of the End station.

End Station

The End tab for a Dynamic Link is shown below.

The unique feature of the End Station selection is the use of a ‘Tracking Strategy’.

Tracking Strategy

Select a Tracking Strategy from the drop-down list. You can choose either a built-in strategy or a strategy you can define yourself (see Tracking Strategies).

Each built in tracking strategy has a set of parameters needed to fully define it. Each strategy must be applied to a specific Group of Stations (see Station Groups) and this is selected by clicking on the highlighted text labelled “Track a Station from”.

As an example of other parameters needed, the tracking strategy we call ‘Constrained Elevation’ allows you to track a station that has the highest elevation but meets the constraint that the elevation is between two limits. This is shown below.

The parameters you can change are bold and highlighted. As you pass the mouse over them, the cursor will change. Click and you can edit them. Click away or press Return, and your changes are made.

For items that are not values, but items selected from a list e.g. the Station Group to be tracked, the operation is slightly different. The cursor changes to a hand when you pass over the item. Click and hold to produce a pop-up list, then drag to the item you want and release. The non-GSO and Highest elevation options in the example work in this way.

The following tracking strategies have been built into the simulation and can be selected directly on the End Station tab of the Dynamic Link

Track a Single Station

This tracking strategy isn’t really a tracking ‘strategy’ at all because it always tracks the same station.

Constrained Elevation

Several parameters need to be given to fully specify this tracking strategy:

• The Group (constellation) to select Stations from
• The elevation constraint type
• Up to two constraining angles (depending on the constraint type)

The selection criterion where more than one stations meets the constraints.

Constrained Distance

This is the same as Constrained Elevation, except that distance from the start station is the constraint.

GSO Arc Avoidance

In this strategy the angle between the candidate station and the nearest point on the geostationary arc,

End stations are only considered if the angle between them, the start station and the GSO arc is above a minimum value. Once again, in the case where there are multiple candidates, the station with the highest elevation or longest hold time is selected.

Avoid Constellation

This tracking strategy ensures that the end station chosen such that the angles between it, the start station and every other station in a given constellation are above a particular minimum value.

What we’re saying here is make sure that the start station doesn’t pick an end station that would have it pointing too close to any of the stations in another constellation.

Nearest

This selects the nearest Station from the Group of possible Stations.

Longest Hold Time

This selects the Station from the Group of possible Stations that is heading towards the start Station and could be tracked for the longest possible time without requiring handover. This is done by calculating the dot product of relative position and velocity vectors.

Furthest from GSO Arc

This selects the Station that has largest angle as seen by the start Station towards the GSO Arc.

Highest Elevation

This tracking strategy selects the highest elevation Station as seen by the Start Station from the selected Group.

Antenna and Beam Options

Selection of the end station also requires that the Antenna and Beam be specified. For the Antenna you can select:

• Highest gain antenna
• Any tracking antenna
• Select an antenna by name.

Beam selection options are:

• Any tracking beam – Visualyse Interplanetary will choose the first available steerable beam
• Highest gain beam – Visualyse Interplanetary will choose a beam from the selected antenna that has the highest gain
• Nearest beam – Visualyse Interplanetary will choose a beam from the selected antenna, whose boresight latitude and longitude are closest to the location of the End station.

If this Link is to be bi-directional you can select a different Antenna and Beam for the EndStart path.

Link Groups

Links can be associated in Link Groups, which are useful in a number of cases. For example:

• To ease the analysis of systems that contain many Links
• For service area analysis
• Analysis of performance of FS Links operating various kinds of diversity
• Combining up and down Link performance for satellite systems.

Links can be in more than one Link Group at the same time. However, when defining Interference Paths that include Link Groups as sources of interference it would be easy to double count some Links if care is not taken in the assignment of Links to multiple Link Groups.

Three kinds of Link Groups can be created in Visualyse Interplanetary, as shown in the figure below.

Link Group - Created Empty

Empty Link groups can be a useful way of managing many Links. An example use would be to look at the effect of a single new Link on many existing Links. One option in Visualyse Interplanetary is to create multiple Interference Paths, one for each existing Link. The second option is to put all the existing Links into a Link group and use that Link group as the Wanted Link.

System Link Group

This Link Group contains a set of Links plus a method for calculating the Link quality of the overall group and also defines how statistics will be collected for the Group.¹

Link to Station Group Wizard

This sets up and manages Links to and from Station Groups. This may be used in service area analysis for example, where the worst point in a geographic area could be found by analysing Links to many test point Stations

Statistics can be calculated for:

• The current time step, based on statistics gathered from all Links in the Group
• The whole simulation run, based on statistics gathered from all Links in the Group
• The whole simulation run, based on a specific statistic which is calculated at each time step

Statistics for each Station over the whole run can be obtained from the individual Link to that Station.

The Wizards can be rerun again to set new values. However, this could require Interference Paths that use some Links in the Link Group to be redefined.

Each Link Group type is now explained in detail

Link Group Created Empty

Empty Link Groups are used as containers for Links. When there is a large number of Links in the simulation, it becomes easier to manage them using Link Groups. At the basic level, you can put all your victim links into one group and all your interferers into another.

To create an empty Link Group click ‘add’ in the Link Group List (accessible via the Model menu or via the Link Group icon in the toolbar). Then select the first option – Link Group.

A new Link Group, default name Basic Link Group will appear in the Link Group list.

Double click on the Link Group or click the Edit button to edit the Link Group.

The edit dialog has two tabs:

1. The Links Tab – add and remove Links from the Link group here.
2. The Advanced tab – to override simulation defaults for statistics collection and Link graphical display characteristics here.

Above the tabs is the Link Group name – by default it will be Basic Link Group (or Basic Link Group 1, 2 etc). You can (should) change the name by click on it with the mouse.

The Links Tab

The Links tab is shown in the figure below. The function of this tab is to select Links from the simulation for inclusion into the Group and also for ordering the Links within the Group.

The left pane shows all the Links defined in the simulation and the right pane shows those that are included in the Link Group.

Transfers to and from the Group are via the and buttons.

Select the Links you want to transfer by highlighting and then press the button to include or remove them from the Group. Alternatively, the button will include or remove all the stations.

Under certain circumstances, the order of Links within the Group can be important – for example, if the Links are Dynamic and ‘competing’ for resources such as Antennas and Beams, those at the top of the list will be processed first.

To promote or demote a Link within the list, select the Link in the right pane and click the button to promote and the button to relegate.

Filter the left pane contents using the filter edit field.

The Advanced Tab

The Advanced tab is used to override simulation defaults for Link colours and for the statistics that are collected.

Statistics to be collected are defined for the simulation as a whole via the Output menu. This is where you tell Visualyse Interplanetary to collect and or all of C, N, I, C/N, C/N+I, I/N and PFD statistics, and where the threshold ratios are set. For each Link Group you can change the parameters collected and/or the thresholds.

To override the simulation settings, check the ‘Override default statistics options’ and click the statistics option button. You will see the Statistics Collection Options tab.

Parameters that are selected in the simulation defaults (see the Overview section of this User Guide) will be checked – if you don’t want statistics on those for this Link Group then uncheck them here. Check any additional parameters you want to analyse and set the threshold levels.

Decide whether you want to generate histograms and the bin size (resolution) for the histograms.

Links can be displayed on map and 3D views either according to the status of the Link (in terms of meeting threshold C/X levels) or according to display properties set here. Click the ‘Link Colour’ button and select the colours to use when displaying the Links in this group.

System Link Group

This type of Link allows Links of groups to be associated and the calculation of statistics across the group to be defined in various ways.

One application of this kind of Link Group is to look at the effects of diversity on the performance of a single hop system.

To create a System Link Group click ‘add’ in the Link Group List (accessible via the Model menu or via the Link Group icon in the toolbar). Then select the first option – System Link Group.

A new Link Group, default name System Link Group will appear in the Link Group list.

Double click on the Link Group or click the Edit button to edit the Link Group.

The edit dialog has three tabs:

1. The Links Tab – add and remove Links from the Link group here.
2. The Advanced tab – override simulation defaults for statistics collection and Link graphical display characteristics here.
3. The Calculation tab – define how statistics over the whole group are calculated.

The first two tabs are the same as for the Created Empty Link Group: the System Link Group has in addition the “Calculation” tab.

The Calculation Tab is where you tell the software how to deal with the calculations across multiple links at each time step

The effect of the various options is described in more detail in Link Group statistics.

Link to Station Group

A Group of Links can be defined to or from a Station Group. This type of Link group has an associated Wizard to help create it.

The Link to Station Group requires a template Link. This can either be selected from the Link list or defined within the Wizard by clicking the Edit button on the first Wizard sheet

All Link types except Transmit can be used as a template Link in this Wizard.

Having defined the Link to use, the next stage is to define the start and end points of the multiple Links. The Link components dialog is shown below.

The Link Group can start or end at each Station of any Station Group in the simulation. The other end of each Link must be a Station named explicitly.

The next two screens (one if using a Receive Link as your template) define the elements to be used for the start and end of the Links. Note that the Stations in the Station Group must have at least one Antenna and beam name in common.

Once you have created this Link Group, you can edit the Group. Select it in the Link Group list and click edit.

There are two tabs, one defining the membership of the group and a second Advanced tab, similar to the two previous types of Link Group.

Link Group Statistics

When we have a group of Links it is possible to look at statistics in three ways:

• Current time step statistics derived from the values of parameters across all links at a single time step
• By aggregating all parameter values across all Links at many time steps
• By selecting one Link at each time step (according to some criterion), build up statistics over many time steps.

We refer to these options as Statistics Now, Statistics All and Calculation Statistics.

Calculation Statistics

Under Calculation Statistics there are several options for the selection criterion. These are:

• Thermal addition
• Maximum Power Combining
• Take Best/Worst Link.

Thermal Addition

Select this option if you have a Link Group that represents a series of hops in an analogue communications chain. Note that the ordering of the Links in the Link Group will represent the order of Links in the chain.

Under this option, the single value used in compiling statistics is the value on the final Link in the group, but noise is assumed to accumulate along the chain. So the noise in Link 3 has a contribution from the noise and interference on Link 2, for example.

The C/X value used is given by:

Maximum Power Combining

Select this option if your Links represent diversity paths between the same two points. In this case, the multiple carriers are combined in such a way that they remain in phase, and add in a maximal sense.

The single value at each time step is calculated in Visualyse Interplanetary in the following way (values in absolute, not dB).

Where Φ is a random angle between 0 and 2π

Worst / Best

Here the contribution to the statistics is taken from worst or best link (according to some defined criterion) at each time step. This could give you the answer to the question ‘For what percentage of time is at least one link suffering interference?’

Choose the third option ‘Take the value of ….’. On this dialog as in others, the bold highlighted text implies a user selection is to be made. Here you can select worst link or best link.

By default, the calculated I statistics will be formed from those Links with the best (i.e. lowest) I and C statistics from the Link with the best C. However you can select the best Link based on any C/X criterion and calculate all statistics and further you can decide to keep with the this Link until the C/X falls below a threshold value.

Let’s look at an example to see why these features are present.

Consider a Gateway Station tracking a constellation of non-GSO satellites. You want to know the interference statistics into the downlink to that Gateway. At any one time, the Gateway may be tracking, say four satellites. The Satellite used for the communications Link will initially be the one with the best BER (or C/(N+I)), but this will be used until the BER rises above a certain value (or equivalently C/N+I falls).

To simulate this, set up four links in a System Link Group and choose best Link by C/(N+I) and stay with a Link until C/(N+I) falls below the threshold.

Example of the Three Types of Statistic

The following example illustrates how the different statistics are derived from all the possible values.

The table below shows the C/I for 3 Links over 4 time steps

Statistics Now would consider at each time step the distribution of C/I. So at t=20 this would be the three values C/I = {15, 8, 22}.

Statistics All would be the 12 values C/I = {25, 21, 15, 17, 27, 18, 8, 14, 22, 23, 22, 24}.

If Calculation statistics was using the worst case, then the worst value at each time step would be used, and the distribution would be the four values C/I = {22, 18, 8, 14}

Tracking Strategies

• Overview of Tracking Strategies

• The Selection Process

• Configuring Tracking Strategies

• Reduction Phase Controls

• Selection Phase Controls

• Handover Options Controls

Overview of Tracking Strategies

Definition: A method applied by a single station, in the selection of a Station to communicate to from a Station Group.

In Visualyse Interplanetary, Tracking Strategy objects can be applied to the end station selection in Dynamic Links.

The method is based on a series of constraints on geometric parameters. The constraints are applied to the end station selection of a Dynamic Link (see End Station).

Visualyse Interplanetary has a number of built in strategies and also has a facility to allow you to create your own strategies.

The Tracking Strategies list dialog can be invoked in the normal ways, i.e.

1. Via the toolbar icon
2. Via the Model menu
3. By right mouse click in the Model view

The first two brings up the Tracking Strategy list from where Tracking Strategies can be Added, Modified, Duplicated and Deleted.

The Selection Process

The concept of the Tracking Strategy is to select a preferred Station or Station(s) that could be used by a Dynamic or Load Link. They can be used in any situation where there is choice – most typically because in the dynamic simulation the relative positions of the various stations are changing.

Examples include:

• Terrestrial mobile network: a mobile selects the base station to use as it moves (for example along pre-defined route or with its location randomised)
• Non-GSO network: an Earth Station will use a different one as the satellites fly overhead
• Aeronautical telemetry: as the aircraft moves it will select a different control station to communicate with
• Maritime voice: as the ship moves it will switch to a different coastal station

A key factor here is there is one station that must select the end station of the Dynamic Link from a set of possible candidates. The Tracking Strategy is used to make that selection.

Consider the example simulation below:

In this case a maritime station has a choice of ten possible satellites to communicate with. Some will be clearly unsuitable – such as those below the horizon as seen by the ship. Hence there are rules that can be geometric that can be used to identify unsuitable candidates. In this case a simple rule could be used:

Elevation angle of the satellite as seen by the ship should be at least 0

This is sufficient for this example as ships in open water can see down to very low elevations. In other circumstances the rules might have to be much more complicated.

In addition, there can be multiple candidates that all meet this minimal rule: in this case there are three satellites visible to the ship.

Hence the basic Tracking Strategy has two stages:

Reduction phase: select from all potential Stations a set of candidates that meet a defined set of criteria

Selection phase: from the Stations that meet the selection criteria, sort by preference and (typically) use the highest preference Station

An additional complication is that sometimes it is preferable to reduce the number of handovers and hence prefer to continue to use the end Station used in the previous time step while it continues to be acceptable (as defined by another set of criteria).

These two stages are reflected in the controls to configure Tracking Strategies as described in the following section.

Configuring Tracking Strategies

Tracking Strategies are configured via the following dialog:

At the top is the name, as for all Visualyse Interplanetary objects.

After the name, the dialog comprises separate sections for the various stages in the selection process:

“Stations must meet all/one of the following constraints”: this is used to define the Reduction Phase

“Choose the…Edit…”: this is used to define the Selection Phase

The “Handover Options” button can be used to give addition feature that can be used to keep tracking the Station used at the previous time step.

Each of these components are described in the following sections

Reduction Phase Controls

The reduction phase controls are shown below.

The reduction phase involves defining a number of criteria that are used to identify whether each of the possible Stations within a Group of Stations is suitable for further consideration (i.e. within the selection phase).

These criteria are geometric, using angles and distances and other geometric values derived at the start point of the Link (e.g. in the examples above, the mobile, aircraft or ship).

The first choice is whether they should all be met or whether it acceptable for the target to meet any one of them: that is done via the “All” or “One” option at the top.

There is then a list of criteria, with controls to add, edit, duplicate and delete. If you click on add you will get a dialog that identifies the types of criteria that can be used, namely:

You can have as many of these constraints as you like in a Tracking Strategy. Each constraint can then be modified using the edit button, which gives options such as shown below.

This can then be modified to change the criteria to use, which can be one of:

• Between: in which case it is necessary to enter the two extremes
• Not between: in this case it is also necessary to enter two extremes
• At least: in this case it is necessary to define the minimum acceptable value
• At most in this case it is necessary to define the maximum acceptable value

Hence in the dialog above the criteria is “at least” and the threshold is set to 10 degrees – in other words the constraint is that target Stations should have an elevation angle of at least 10.

Selection Phase Controls

The selection phase takes the sub-set of suitable end Stations from the reduction phase and orders them according to a criteria. The controls are shown below.

There are built in the following standard selection criteria:

• Highest elevation (useful for satellite selection)
• Longest hold time (based upon whether the target end Station is heading towards the tracking Station or away from it)
• Closest (useful for base station selection for terrestrial systems)
• Furthest from the GSO arc (e.g. to undertake EPFD studies under Article 22.2 of the Radio Regulations)
• Random station (this can be very useful to just use this part of the Tracking Strategy to undertake some forms of Monte Carlo analysis)

There is also an option to further customise the selection phase by clicking on “Advanced” and then defining using the following dialog:

The starting point is the ordering criteria which can be one of:

• Elevation angle
• Azimuth angle
• Distance
• Difference in latitude
• Difference in longitude

Then there is the sort order which can be either highest first or lowest first, and with options to take the highest or lowest in absolute.

Finally, there is the preferred position on the list – i.e. the 1st, 2nd, 3rd etc highest on this sorted list

There are additional fields to manage this list sorting process:

• What to do if there are fewer Stations on the list than the preferred position? For example, if the preferred position is 3rd but there are only on 2 on the list. A field can be used to either select the next best or for the link to fail.
• What to do if the preferred Station has already been selected by an Antenna at the tracking Station? This would clearly be inefficient given Antennas are a limiting resource for the simulation. Hence the Tracking Strategy can check to avoid such duplication.
• The converse is what to do if there are no available resources (e.g. tracking Antennas or electronically steerable Beams) available on the preferred end Station? Should the Link fail or take the second best?

Note that the last of these effectively determines whether the Tracking Strategy returns a single Station (the preferred one) or a list of suitable ones, with the preferred one at the top.

Handover Options Controls

An option within Tracking Strategies is to once an end Station has been selected at one time step, to continue to track it while it meets a certain set of criteria. This is done by the “Handover Options” as in the following dialog:

Note that these options are by default switched off so that the Tracking Strategy would at each time step start from scratch with the reduction and selection phases.

If activated it allows a set of criteria to be used to determine whether the current end Station is still suitable. These criteria are the same as those in the reduction phase described above in Reduction Phase Controls.

The handover process can also be re-set after a specified number of time steps: this can model systems that are designed to avoid handover during a call. There are therefore options to continue tracking for:

• Exactly a certain specified number of time steps
• A number of time steps selected at random with uniform density between zero and an entered value

Interference Paths

The interference scenario is defined in terms of any number of Interference Paths. An interference path consists of a wanted Link or Link Group and a number of interfering Links or Link Groups.

All Links defined in the simulation are available for selection as interferers.

Where multiple Links are defined as interferers, the aggregate interference power is automatically calculated.

The Interference Paths dialog can be invoked in the normal ways, i.e.

1. Via the toolbar icon
2. Via the Model menu
3. By right mouse click in the Model view

There are three parts to the dialog:

• Select the Victim Links
• Select the Interfering Links
• An advanced tab where you define the interference calculation options

Select the Victim Link(s)

Select either a Link Group or a Link from the Link List. If you select a Link Group only, Interference paths will be set up for all Links in that group.

Select the Interfering Link(s)

On the interfering links tab, the list off all potential interferers is displayed in the left-hand pane. Any Links or Link Groups currently selected as interferers are shown in the right-hand pane.

Where a Link or Link Group is bi-directional, both directions (start – end and end start) are given as options.

To include a Link Path as an interferer, move it to the right-hand pane using the arrow buttons.

Advanced Interference Path Options

The Advanced tab includes several parameters that have an effect on the interference calculation.

Each calculation option is described below

Force Co-frequency

Checking the “Force Co-Frequency” box forces all interfering Links to be co-frequency with the wanted Link, for this interference path only. This option is used for worst case analysis.

An example use of this option would be if many interfering Links have been entered with different frequencies according to some channel plan, and a worst-case analysis is required. The worst-case analysis may not include the channel plan. Forcing cofrequency would allow the existing Links to be used without losing the channel plan data.

This option should not really be used to scale systems from, say Cband to Kuband. The adjustment is only applied when the bandwidth overlap factor is calculated. Therefore, frequency Antenna characteristics and pathloss would not be accounted for correctly.

Check Overlap

Where out of band emissions are of interest, it may be that you want to include interferers that have no frequency overlap with the wanted carrier. In combination with frequency off-set advantage, the Check Overlap option can be used to model the effect of out of band or spurious emission.

If Check Overlap is set then all interferers must have overlap in their allocated bandwidths to be included in the interference calculation. If it is not set then interfering paths will be included whether or not they have overlap in bandwidth.

Exclude Wanted Beams

This option is useful when analysing intra-system interference and considering a Link Group as the wanted element in the interference path.

In this case the wanted Links would also be used as interferers i.e. you can select the same Link Group as the interfering element.

With the Exclude Wanted Beams option selected, interference into a particular wanted Link would be considered from all the other Links in the group, but not from any links using the transmit beam of the wanted Link.

Include On-Tune Rejection for Radar Systems

If this field is activated and the relevant Carriers have the radar fields defined, then the On Tune Rejection (OTR) will be calculated according to ITU-R Rec. M.1461 “Procedures for determining the potential for interference between radars operating in the radiodetermination service and systems in other services”

Calculate Interfering Signal using Victim Frequency

When using the IMT-MODEL gain pattern (e.g. for IMT-2020 or 5G studies) there can be a different gain pattern for co-frequency and non-co-frequency scenarios. The way to define this in the Antenna Type is described in IMT-Model Non-Co-Frequency Parameters.

By default the interfering signal is always calculated using the centre frequency of the interfering link. However to activate the non-co-frequency gain patterns it is necessary to use the centre frequency of the victim link.

This can be achieved by checking the option “Calculate Interfering Signal using Victim Frequency”.

If this is enabled then the interfering signal will be calculated using the victim centre frequency and hence allow the antenna type to identify if the path is co-frequency (to the IMT-MODEL antenna) or non-co-frequency.

Note that this will not affect other calculations, in particular the mask integration adjustment or NFD.

Polarisation Advantage

When polarisation advantage is included, the interfering power level may be reduced by a set amount.

The options available in the drop-down list are:

• None
• ITU Radio Regs
• User Defined

The table below shows the numerical ratios to be used for polarisation isolation between two carriers when the Radio Regulations option is selected.

When User Defined is selected, this table is available for editing via the dialog below. By default, the advantage is only applied when there is main beam to main beam coupling between the wanted receiver and the interfering transmitter. The same user defined table is used for all Links

Frequency Offset Advantage

It is possible to define a dB advantage relating to the offset of the centre frequencies of the wanted and interfering carrier. The effect is to reduce the interfering carrier level or (equivalently the wanted receiver response) by a number of dBs at each defined frequency offset.

This could be used, for example, to model the out of band interference of a narrow band carrier into a wide band receiver with a known filter characteristic. The filter characteristic would be reflected in the off-set advantage.

Details of the effect on the interference calculation are given in the Technical Annex.

If multiple interferers are defined, they will all be affected by the frequency off-set advantage.

To use this advantage make sure the Use Frequency Dependent Advantage’ box is checked. The characteristic shape can be edited by clicking the Change button. The following table will then be available.

You edit the table directly or use Copy/paste of data from other applications.

Other Advantages

The Other Advantages field can be used to specify a dB value to be added or subtracted from each interfering signal. This may be used in a number of ways. For example, a real value for polarisation advantage might be known from Antenna performance data and from the polarisation plan definition. The polarisation isolation would be entered as a positive number in this field.

Alternatively, this factor could be used to model carrier fading (when C/I is being considered) by entering a negative number in this field. The negative number may be equal to the expected rain fade for example.

Bandwidth Adjustment Factor

The various possibilities for bandwidth adjustment factor determine how the overlap between the wanted and interfering carrier is taken into account.

The options available are:

• Based on spectral density - ignoring bandwidth factors and taking the ratio of spectral densities as the C/I
• Assuming multiple interfering carriers - where the interferer has a narrower bandwidth than the wanted carrier, interferers are stacked into the wanted carrier bandwidth. If the interferer has a wider bandwidth than the wanted carrier then the overlap of the two is calculated.
• Based on overlap of a single carrier - this explicitly calculates the proportion of the interferer that falls into the wanted bandwidth
• Integrate masks – calculates the Net Filter Discrimination (NFD) based upon the TX and RX masks. There are a number of alternative NFD calculation methods as described in the Technical Annex.
• None - the ratio returned in this case is just the ratio of the total received powers of the wanted and interfering carrier at the wanted receiver.

Each option is described in detail in the Technical Annex.

Solar System Objects

Visualyse Interplanetary includes an additional list of objects to define the Solar System. This can be found under menu option Model | Solar System.

If the JPL ephemeris file is not specified, then Visualyse Interplanetary will work in legacy mode. In this case, the list will only contain the standard Visualyse Professional Earth which is a sphere of radius Re = 6378.145 km.

If the JPL ephemeris file is specified, then this will show the list of available celestial bodies:

You can add, edit, duplicate and delete celestial bodies, allowing moons of the major planets and asteroids to be entered.

In the future, this could be extended to include the ability to import additional celestial bodies using a text file format (e.g. using orbit elements or J2000.0 state vectors).

Each object can be viewed or edited using a dialog similar to this:

The watch window can also be used to view the configuration parameters and also calculated parameters:

Note that the Earth model in Visualyse Interplanetary is the standard WGS84 ellipsoid and that each object has defined what object it orbits.

Each celestial object has flags to identify if it has {Ground, Atmosphere, Seas}. This field is used to identify what types of station are permitted – so, for example, aircraft would not be permitted on the Moon.

Configure and Run Simulations

This section of the User Guide concerns the set-up and analysis of simulation runs, using elements and a scenario already created.

This section is structured in the following way.

Run Parameters describes how to set run parameters including duration, time step resolution.

View Properties gives details of how to change the properties of the map and 3D view windows to improve the graphical feedback you are getting from Visualyse Interplanetary.

Change Variable Wizard shows how to modify large groups of objects using the Change Variable wizard.

Run Parameters

This section describes the default options that can be defined in Visualyse, and also how the different views can be configured. Configuration of the graph views is described in Graphing .

• Visualyse Default Parameters
• Population Data Settings
• Run Time Parameters and Simulation Control

Visualyse Default Parameters

A number of default settings will apply to all simulations opened on your PC. These settings are defined via the File menu item.

Selecting 'Visualyse Settings' from the File menu brings up the following dialog box.

Run Status shown in the bottom right of the can be displayed in one of four ways:

• Time of day – the current simulation day, hour, minute, second and millisecond is shown
• Percentage Run – based on the number of time steps specified and the number already executed, the percentage of the run completed is shown
• Elapsed time – shows the elapsed time simulated since the start of the simulation
• Time step – the number of time steps already executed is displayed.

Display Precision determines how many decimal places are shown in the calculated fields in Visualyse Interplanetary dialogs. You can also determine whether to trim all trailing zeroes.

Defaults – when objects are created in Visualyse Interplanetary they have an associated frequency. This can be edited in the object dialog, but initially will be simulation default value that is set here. You also decide whether an antenna and carrier are created by default in each new simulation and whether Logs/Statistics/Define Variables are duplicated when duplicating SIM objects. The final option is the default size of the ground track.

Optimisations may have some effect on the speed at which a simulation runs:

• Calculation of lat/long histories is needed if you are going to display ground tracks. If not they are simply an un-necessary overhead
• Calculation of beam az/el for tracking beams is needed if you are going to collect statistics or do some other analysis on these pointing angles. Within Visualyse Interplanetary geometry is calculated in our internal Cartesian co-ordinates and for beam that track, the simulation can work directly in these co-ordinates.
• Rate of change of antenna pointing: only enable this option if you are interested in it specifically.

GIMS – selecting the ‘Use GIMS Shaped Beams’ option means that when using contour beams, the interpolation to points between the contours will use the GIMS algorithm rather than any of the other options that you can define in the Antenna Dialog. It is important to note that if you do not have the latest GIMS DLLs installed on your PC, this function will not work and the software will default to linear interpolation, no error message will be generated when this happens.

You can also set the location of the ITU GIMS Database by clicking on the "..." button and selecting an appropriate database.

Startup – check for updates. You can get Visualyse Interplanetary to by default check online for a new release. This might require you to change the settings on your firewall to give Visualyse Interplanetary permission to access the internet.

Graphics

• Use high-resolution terrain graphics – You can set whether Visualyse Interplanetary will use high-resolution graphics when drawing terrain data on the Map Views. Note: users with limited graphics card memory are advised to leave this unchecked (the default setting).
• Use Direct 2D for Graphs – Disable this setting on PCs where there are noticeable performance issues when displaying graphs with a lot of graphical elements. Note: this only tends to happen on low powered graphics cards.
• Use Direct 2D for 2D Maps – Disable this setting to use “classic” OpenGL. This may be beneficial in some scenarios.

Autosave – save when SIM end. You can set whether Visualyse Interplanetary will automatically save the file when the SIM reaches the end.

Solar System Data Settings

In Visualyse Interplanetary is necessary to have access to one of the JPL ephemeris data files. This file is called something like:

lnxm13000p17000.431

The first time that Visualyse Interplanetary is run it should be configured to point to this file using the menu option File | Solar System Settings. This will open the following dialog:

The UTC to Terrestrial Time (TT) offset allows the dynamic time to be defined relative to UTC.

Population Data Settings

Selecting “Population Data Settings” from the File menu allows you to set the directory that contains the population data files:

The population database is the NASA gridded population of the World (GPW). This gives the population in each 30 arc-second pixels over the Earth’s surface from 60S to 85N.

The data was downloaded from the Centre for International Earth Science Information Network (CIESIN) at Columbia University as described here:

http://sedac.ciesin.columbia.edu/data/set/gpw-v4-population-count-rev11

Note the recommended citation for use of this data is:

“Center for International Earth Science Information Network - CIESIN - Columbia University. 2018. Gridded Population of the World, Version 4 (GPWv4): Population Count, Revision 11. Palisades, New York: NASA Socioeconomic Data and Applications Center (SEDAC). https://doi.org/10.7927/H4JW8BX5”

The data was provided as 8 text format tiles of size 90° x 90° in (latitude, longitude), in total nearly 5 GB of data. To facilitate its use within Visualyse Interplanetary, this data was converted into just over a thousand binary files covering 5° x 5°, each just over a megabyte in size, then collected into a zip file.

Two versions of this data were processed, namely that for 2015 and 2020. These can be downloaded from the Transfinite website:

https://www.transfinite.com/content/population_data

Having downloaded the relevant zip file, the files it contains should be extracted into a directory on your PC, for example something like:

D:\5_deg_population_files_2015_gpw-v4-rev11

D:\5_deg_population_files_2020_gpw-v4-rev11

Note that Visualyse Interplanetary checks the directory to ensure there are the required number of files and they all are the right size.

More information is available in the White Paper on using Population Data in Visualyse.

Run Time Parameters and Simulation Control

Selecting Time Settings from the Simulation menu, brings up the following dialog box

This is where the simulation start time, time step size and run duration parameters are defined.

Start Time

Selecting a date and then a time sets the simulation start time. Click on the date field and a popup calendar will appear. From here you can select a date.

The dates for the current month are shown. The currently selected date is highlighted in grey. Today’s date is shown with a red border around it. You can select another date in the current month by clicking on it. At that point the popup will disappear. You can automatically select today’s date by clicking the Today button.

The black arrows allow you to change forward and backwards through the months. If you click and hold where the month is displayed, a pop-up will appear. From there, you can select from months around the currently selected month. If you try and select beyond the range in the pop-up, the list will scroll.

You can also type directly into the date field. The software will recognise a number of different formats including all the standard abbreviations for months and years.

Once the date has been set, you can then move on to change the time. The time can be entered in the edit box.

Note that you can type in a time that includes seconds or milliseconds. When seconds are present, the time is shown in the “00:00:00” format. When milliseconds are present, the time is shown in the “00:00:00.000” format.

Time Step Size

The most important time related parameter in most dynamic simulations is the step size. To change the time size, simply change what is written in the box. The software will take care of any problems with formatting. You can type the elapsed time in a number of formats. All of the following are accepted:

Once you have finished typing, press the return key, or tab away from the control. The return key will not close the dialog under these circumstances.

Run Duration

Run duration can be specified in one of three ways:

• From the number of time steps
• By defining the total elapsed time
• Selecting picking an end time

You can select which of these options you want to use by clicking on the appropriate check button.

If you choose to specify a number of time steps, the elapsed time and end time will automatically be calculated and displayed. The equivalent applies for the other two. That way, all three are kept in synch.

To change the elapsed time, simply change what is written in the box – the formatting is the same as for the time step size above.

If the elapsed time or end time options are selected, the number of time steps will be recalculated.

Simulation Video Style Controls

The simulation can be controlled from the Simulation menu or by mouse clicks on the video controls

The video control buttons are shown below.

Each control is now described (working from left to right)

Reset

This resets the simulation to t = 0. All statistics collected are erased if the simulation is reset. Pressing this is equivalent to selecting reset from the Run menu.

Stop

This stops the simulation. This is equivalent to selecting Stop from the Run menu.

Pause/Step

The first time this button is pressed, the simulation is paused. Each subsequent time, the simulation is progressed by a single time step. This is equivalent to selecting Pause from the Run menu. The space bar can also be used to pause and step the simulation. However, the space bar only has this function when running in Interactive mode.

Run Interactive

This sets the simulation running, updating all views at each time step. This is equivalent to selecting Run Interactive from the run menu.

Run Non-Interactive

This sets the simulation running without updating any views. This gives optimum performance. Pressing this button is equivalent to selecting Run NonInteractive from the Run menu. The simulation can be run even faster by pressing the space bar whilst running in Non-Interactive mode. This switches off all updates including those to the status bar.

View Properties

Visualyse Interplanetary includes a number of different types of View Window accessible from the Window menu or from the toolbar icon shown:

Plate Carrée view – a plane projection view of the simulation

Mercator view - a plane projection view of the simulation

3D view – an orthomorphic perspective projection view of the simulation from a point in space

Model view – a hierarchical view of the objects in the current simulation

Watch window – select a number of variables to ‘watch’ in a window

Table view – displays multiple parameters across multiple objects, e.g. look at the I/N of all victim Links within a Link Group

Terrain profile

Frequency view

Each of the different types of view window can be customised in various ways. This section looks at the properties of each of the views.

Map View

There are two forms of map view showing two types of projection, namely Plate Carrée and Mercator. For more information on these projections see:

http://en.wikipedia.org/wiki/Map_projections

These views can zoomed and panned using the move by:

• To move the map: click the left mouse button and while held down move the move
• To zoom the map in and out: use the mouse scroll wheel

There are a number of mouse “modes”, including:

Default mode – mouse moves the map

Station move mode – mouse used to move stations

Zoom mode – mouse used to select area to zoom into

Terrain mode – mouse used to select area to load terrain region (see Modules User Guide)

Path profile mode – mouse used to create new path profile (see Modules User Guide)

Move path profile mode – mouse used to move any of the path profile start or end points (see Modules User Guide)

Land Use mode – mouse used to select area to land use terrain region (see Modules User Guide)

Selecting Properties from the View menu (with a Map window active) or button from the toolbar brings up the Edit Map View dialog.

The properties dialog is also one of the options on the pop-up menu that can be accessed by right clicking on the map, as shown below:

Note a slightly different menu will appear if you right click in locations where there is an Area Analysis, as discussed in Area Analysis Pop-Up Menu.

This menu can be used to:

• Create a new station at the position clicked
• Jump to a specific country as in the figure below:

• Export to Google Earth (as described in Interface to Google Earth)
• Set the current view configuration as the default one so that all new views of that type will open configured to look identical to the present one
• Restore Default Scheme: to change the configuration of the current view back to the default values
• Properties: this opens up the view properties dialog.

The view can be copied to clipboard using the Edit menu option or toolbar icon .

The map view properties dialog consists of five tabs:

• Features – the most regularly used features are presented in this tab
• Adornments – grids, titles and tick marks are defined here
• Overlays – here you can add Area Analyses, Terrain colours, Land use data and user defined bitmaps to enhance your output.
• Path Profiles
• Countries – schemes for colouring the map by country groups are defined here.

Each tab is described in the following sub-sections.

Features Tab

The General tab is shown below.

Switch the beam footprint and the Links on and off by checking or unchecking the boxes. The options buttons allow you to change the display properties.

Beam Options

To change the beam display options, click the options button next to “Show beams”. This will bring up the beam display options dialog (shown below).

The dialog is split into two sections. The first section allows you to specify the footprints you want to display and their relative gain levels. Line styles can be selected for each beam contour that is being displayed.

If you want to display several footprints between two relative gain levels, set the top and bottom contour levels to the extreme values and click “Space Levels Evenly” to automatically set the levels for the footprints in between.

There is an option for filling the beam footprints with the line colour. Label display and formatting is also user definable.

The “Colour Options” section allows you to choose how the beam footprints are coloured when displayed on the map view.

The default option allows you to colour each footprint according to its relative gain level. Clicking next to the box where the level is set, sets the colour and line style.

The other option is to colour beams according to the Station Group, Station, or Antenna that they belong to.

To choose which one of these you want to colour by, select the ‘Colour according to’ radio button and click on the drop-down box activated next to the button.

The levels are still set at the top of the dialog. However, the colours are assigned according to the Group / Station / Antenna / Antenna Type.

To change the colours associated with each Station Group, Station, Antenna, Antenna type, click Assign Colours. This will open the Assign Beam Colours dialog.

This dialog allows you to navigate to the objects you have chosen to colour by and select a colour and line style to apply to the beams.

Link Display Options

To change the link display options, click the Options button next to Show links. This will bring up the Link Display Options dialog (shown below).

There are three options. You can display links according to one of the interference parameters (I, I/N, C/(N+I) etc.). The interference parameter is chosen from the drop-down list. You can then choose the colours for good, bad and unclear links.

The other two options allow you to display the links in their own colours or in the colours of the link group. These colours are set by editing the individual Links and Link Groups themselves.

Station Options

Station names can be switched on and off for normal stations and for marker stations. The font can be set as well. All fonts will now be displayed at the font size you choose.

Station ground track length can now be set on the dialog – note that this track length is applied to all map and 3D views. Colour and line style are set using the new line style control.

Advanced Contouring

This option can be used to produce contours that show how link and station variables change over an area. For example it could show contours of where the interfering signal strength reaches a certain level.

As this is similar to the Area Analysis it is described further in Advanced Contouring using Groups.

Adornments

Adornments can be added to the view to explain what is being displayed or to enhance its appearance. The dialog is shown below.

There are two sections to the adornments tab. The first deals with the latitude/longitude grid and the second deals with borers titles and axes.

Latitude/Longitude Grid

You can show or hide the latitude/longitude grid by ticking the check box at the top left of this tab. You can also set the line style for the grid lines. The grid size is defined by latitude and longitude spacing – type the number of degrees you want between each grid line in the boxes on the right-hand side of the dialog

Border, Title and Axes

If you switch this option on, a border will appear around the map area. You can change the colour of the border by clicking in the colour box.

The view title and subtitle are displayed in the centre of the top part of the border. Labels are shown along the latitude and longitude axes. You can set the spacing for tick marks on these axes. The fonts for all these can be adjusted.

When all the adornment options are switched on, the view will look something like the one below.

Overlays

The overlays tab allows you to add features to a map which will enhance your output aesthetically and can also add a large amount of easily digestible information.

Overlays fall into four categories:

1. Area Analysis – any analyses produced so far in the simulation can be overlaid on all views
2. Terrain regions – if terrain data are included they can be selectively displayed as a colour coded overlay
3. Land Use Regions – used in the determination of clutter loss, Land Use data can also be displayed as colour coded overlays.
4. User Defined Overlays – allows you to add additional information onto the view including point, vector, and raster data, as explained below

There are four types of User Defined Overlays, namely: point, vector, drawing objects and raster data. The required file formats for all overlays are described in the Technical Annex.

Point data allows specific locations to be marked and given a label. An example of point data is the User Defined Overlay “Capital Cities of the World”, as in the figure below:

Vector data allows lines to be drawn at specific locations: this could be to show roads, railways, or borders. An example of vector data is the boundary of the Washington BEA licence as shown in the figure below.

Drawing objects allows simple shapes (rectangles, ellipses and grids) to be drawn at specific locations.

Raster data is graphical data such as maps but could include images of (say) population density or other information. These can cover the entire Earth or just a small part, defined using a rectangle. The example below shows a map from the Ordnance Survey (OS) in the UK overlaid on the Mercator view:

Note that raster data will have been generated assuming a specific projection and therefore care should be taken when displaying on either the Plate Carrée or Mercator view to ensure it is appropriate. The 3D view works like a Plate Carrée at large scale (i.e. the whole Earth) and Mercator and small scale (zoomed far in). Vector and point user defined overlays will work in any projection.

These four user defined overlays, together with the Area Analysis, terrain and land use overlays, mean that there is a lot of information that could be displayed on either of the map views or the 3D view. Indeed typically the key issue is how to select and configure what is shown.

A number of controls can be used to manage what is shown on the views, including:

• Check boxes to show or hide each of the items
• Controls to change the order in which each layer is display
• Controls to change the degree of transparency from one layer to the layers below

The final image is built up by adding each layer on top of the other with the degree of transparency as requested.

The result of combining these three layers is a composite in which the graphics are merged so that lower layer information can be seen due to the transparency of the higher layers.

The arrow keys on the View Properties Overlay’s tab can be used to move the position of:

• An overlay category (e.g. Area Analysis, Terrain, Clutter, User Defined) with respect to another overlay category
• An overlay with respect to other overlays within that particular overlay category

Select the item of interest (category or overlay) then click on the up or down arrow as required.

To change the level of opacity (and hence its transparency) of an overlay, select it and then click on the Transparency control, as in the figure below.

The following should be noted:

• It is easy to overload the view with too many overlays: select the ones you want and hide others
• The most important overlays should be highest on the list and less important ones lower down
• The level of transparency of each overlay can be used to show more or less of the lower layers

Tip: Colours of terrain and land use pixels can be selected to avoid clashing with other overlays. For example if an area analysis of coverage from a base station uses green and yellow to plot signal strength, select different colours to show the terrain heights or land use codes.

Path Profiles

Where terrain path profile views have been created, they are indicated on map views as a coloured line. The Path Profiles dialog lets you control how that line, and any text associated with it, is displayed.

Countries

The final tab on the Map View Properties dialog is the Countries tab. This allows you to set the display options for the country polygons in the map.

The main function of this tab is to allow you to set the colours and outlines of the countries on the map. A list of all the countries is displayed on the left-hand side of the dialog. Each country has a coloured square next to it. This represents the colour and outline that will be used to display that country.

To change a country’s colour, first select it in the list. At the top of the list are two controls one to select the colour and one to set the outline.

When you change the colour or line-style, these will be set for the selected country. If you want to set these colours for another country, first select the new country. Now all you need to do is click the colour or outline button itself (not the drop-down) and that colour or style will be applied.

You can change more than one country at once by applying colours and styles to a multiple selection. You can also click the Colour All button to apply the current colours to all the countries in the list.

At the bottom of the list is a drop-down that allows you to show only certain groups of countries. Examples are - All countries, Continents and ITU regions. Having selected a group, you could apply colours to all countries in the group.

As well as country colours, you can select whether to show US state borders or rivers and lakes. You can also choose the sea colour.

Choose whether you want to show country names. The font can be set for these as before. However, fonts will now be displayed at their actual point size.

3D View

The 3D view display properties are almost identical to the map view properties. There are however a few small differences.

On the features tab, in addition to ground tracks, an option to display space tracks is provided.

It isn’t possible to use the border feature and the countries cannot be displayed individually. Instead on the Adornments tab there are options to set a single, general, country border and sky colours.

On the beam display options dialog, there is an option to display the beam cones.

The biggest difference between the two dialogs is the addition of an extra tab called Viewpoint. This is only applicable to the 3D view where the view point can be changed. In the map view this is fixed.

This tab allows you to set the view position itself. The default option is user defined. This allows you to:

1. Set a specific lat/long/height to view from
2. Change the view position interactively dragging the globe in the view window.

With the user defined option, you can choose whether you want the planet to rotate in the view when the simulation is running.

The other option allows you to view from a particular station. This allows you to sit on a satellite say and see what the world looks like from there – a useful way to understand many aspects of the geometry and dynamics of, for example, a non-GSO scenario.

The direction of view is always towards the centre of the planet.

Schemes for Map and 3D Views

A feature of both property dialogs is the option to use schemes. These are simply groups of view settings that can be instantly called up. To select a scheme, click on the drop-down box at the top of the dialog. The scheme contains settings for all the tabs.

You can create your own schemes. To do this, simply click Save as. You will be asked to provide a name for the scheme. Click OK and the scheme will be added to the list. You can delete schemes that you have created if you make a mistake or you no longer need them.

Model View

An example of the Model View is shown below.

This view has several functions:

1. To show you the structure of the scenario you have created. The view allows you to see, browse and edit the objects that already exist
2. To create new objects – the view acts as an alternative to the menu bar and icon. Clicking the ‘Add’ button (top left) allows you to create new objects.
3. Duplicate and delete buttons allow you to duplicate and delete selected objects
4. Load and Save – this allows you to save objects to a location outside the simulation as a text file. You can then edit the text file and re-load or load the same object into a new simulation.

Watch Window

The watch window is a way of monitoring the evolution of selected simulation variables. Select and order a list of variables and watch as they are interactively updated as the simulation runs.

You can pick Carrier Station, Station Group, Link and Link Group parameters.

In the example above a Watch Window has been set up to show intersatellite C/N and downlink C/N (Link attributes) and the end-to-end C/N (a Link Group attribute). The scenario is the downlinking of information from the International Space Station to an Earth Station via one of two TDRS satellites

To create a new Watch Window select New from the Window menu, then pick Watch Window from the list. A blank Watch Window (shown below) will be created.

To add a variable to click the ‘Show Object Tree...’, button in the top left. This reveals the objects from which you select the variable of interest.

In the figure below you can see the Carriers, Links, Stations and Link Groups in the simulation. The small arrow to the left of each object indicates that there is structure contained within the object. Click the arrow to reveal the parameters that can be watched.

The data in the watch window can be copied at any time using the copy button at the top right. The copied data can be pasted into other applications in a tab delimited form.

Tip: It is a very good idea to use the watch window to look at the wanted and (where applicable) worst single interferer link budgets. This allows you to get a good idea of what the main issues are, and sanity check the results.

If you are unsure about why the results are as they are this is a good place to start!

Table View

Table View allows you to view multiple parameters across a Group of Links or Stations, or from the full Link or Station list in a single Window.

The example below shows the method for selecting which variables from a group of stations to display

Once the variables are selected, they can be displayed in rows or columns for each station. The figure below shows the latitude, longitude and height for 19 stations in a hexagonal deployment in Europe.

Terrain Profile

This view gives a spot height profile between any two points on the surface of the earth – it is described in the Modules User Guide

Frequency View

The frequency view can be used to show graphically the spectrum mask of transmitters and the receive filter characteristics, together with the frequency offset between them.

An example is shown in the figure below, taken from the “Digital Dividend” example file “3G into DVB Punched Holes.sim”.

The frequency view shows in the top half the transmit mask in terms of relative power in dB against frequency offset from carrier centre frequency. In the bottom half, using the same frequency scale, is the attenuation of the receiver in dB – again with respect to frequency offset from carrier centre frequency.

The two frequency scales are aligned to show to scale the relative frequency offset of the two links. In addition the central frequencies of the two links are displayed above each mask.

You can open a new frequency view by selecting menu option “Window | New | Frequency view” or clicking on the icon

Having done that you can configure it by right clicking within the view to open the following dialog:

The first step to configure the view is to select the receiver of interest: the RX mask shown will use taken from the carrier for this link. The frequency axis of the view will have its zero frequency offset defined by this link’s centre frequency.

Then the transmit mask can be defined by one of two ways:

1. From the carrier of the worst single interfering link into the selected victim link
2. From the carrier of a specific link

In both the RX mask and TX mask cases if the link is bi-directional it will be necessary to select the direction as there could be different carriers and / or different frequency offsets between forward / return directions.

If the TX mask is taken from the RX link’s worst interferer, and the interference path has the “Bandwidth adjustment” option set to “Integrate masks” then the calculated Bandwidth Advantage will be shown in the view’s bottom left corner.

The view can be copied into the clipboard for pasting into other applications by clicking on the copy icon or selecting menu option “Edit | Copy”.

Note that this view updates during the simulation, so that if a frequency hopping system is used it will show the frequency offsets for the current time step – see the “Short Range” example file “WiFi and BT.SIM”

Change Variable Wizard

The final item under the Model menu is the Change Variable Wizard.

This allows any parameters of a group of stations or links to be changed to a new value, to take random values in a given range, or to vary linearly across the group between two values.

The Change Variable Wizard is accessed via the Edit menu. The first screen in the Wizard is shown below.

The two parameter groups on this screen are ‘Container’ and ‘Variable’. The ‘Container’ defines the object which contains the variable to be changed. This object can be chosen from any of the object lists (Station, Link, Beam Type etc,) or from any Station Group or Link Group.

The ‘Variable’ group is used to define the variable to be changed. In the example above, the antenna height of all the stations in the Group ‘Constellation’ will be varied.

The second screen is shown below.

The options in this screen are:

• Set all the variables to the same (user defined) value.
• Spread the variable between two defined bounds - variability can be linear, starting at the lower bound for the first variable on the list, or it can be random.

If random is selected then a set of random numbers will be used. For repeatability the same set of random numbers will be used each time the change variable wizard is run: hence if you want a different set of random numbers you must click on the “Seed” button.

If you do not there will be correlation between sequences, such as in the example below where the latitudes and longitudes have been randomized from the same seed:

The options under ‘Action’ (click the arrow to the right of the button) apply when a ‘Single Fixed value’ is selected. The options, which determine how the parameter placed in the Value field is used, are:

• Set – this option sets all the parameters to the value input by the user.
• Add – takes the value input and adds it to the current value. This could be used to shift a group of stations in Longitude, maintaining the relative positions of the Group
• Multiply – take the value input and multiplies the current value.

Selecting next will finish the Change Variable Wizard and change all the selected variables.

Example applications of the Change Variable Wizard are:

• Randomise the antenna heights in a Group of terrestrial Stations, between defined limits.
• Change the power on multiple Links in a Link Group.
• Change the Antenna Type on all the Stations in a large Group.
• Randomise Earth station latitudes and longitudes or antenna azimuths and elevations.

Data Analysis

• Visualyse Statistics Collection
• The Visualyse Log File
• The View Results Dialog
• Graphing
• Area Analysis
• Interface to Google Earth

Visualyse Interplanetary Statistics Collection

The following parameters are gathered:

• Worst data value and simulation time of worst data value
• Average data value (this is a mean value)
• Standard deviation of range of data values
• Number of events
• Longest event length and time of longest event
• Average event length
• Probability distribution of data values

The probability distribution is created using an array of bins using the bin size specified. Visualyse Interplanetary puts values in the bin by rounding down: hence if the bin size is 1 dB and the C/N = 18.3 dB this will be placed in the 18 – 19 dB bin which is labelled as 18 dB.

Where appropriate, Visualyse Interplanetary will calculate statistics in dBs or in absolute value. In some cases, the parameter values may be mathematically undefined if they are collected and calculated in dB. Visualyse Interplanetary will return values for these statistics based on default dB values – for example of there is no signal level (0 watts) Visualyse Interplanetary defaults to a value of -3000 dBW.

Link Interference Statistics Collection

Interference statistics collection is specified at simulation level. You choose what interference statistics you want to collect and whether these statistics should apply to just wanted Links and Link groups or all the Links and Link groups.

To allow for special cases, can override the document level settings in any Link or Link Group object.

To specify the statistics you wish to collect, select Statistics Collection from the Output menu. This will display the Statistics Collection Options dialog.

The dialog has two tabs. The first of these is the Link Statistics tab. This allows you to choose which Link and Link Group interference parameters you want to look at.

To choose an interference parameter simply check the appropriate box. A threshold can then be specified for this parameter. The threshold is used by Visualyse Interplanetary to define an interference event when calculating percent time interference is seen or the number and length of interference events.

For PFD and EPFD there are additional options for specifying the reference bandwidth. Note that PFD and EPFD cannot be selected at the same time. If you switch one on, the other will automatically switch off.

The “Calculation Options” button allows you to define whether the statistics for each of the standard link metrics are calculated in dB or absolute. For example, when calculating the “mean I/N” is it the mean of the I/N in dB or the I/N in absolute?

A separate option allows you to say whether you want to generate histograms (probability distribution functions). If this option is chosen, a histogram is created for each of the selected interference parameters. The size of the bins (the resolution) of these histograms can also be specified.

Finally, you can choose whether the statistics are collected for all Links and Link Groups or just for wanted Links and Link Groups.

User Defined Statistics

There is a second tab labelled the Advanced tab.

From this tab you can choose any parameter in the simulation and collect statistics on that.

Click the Add button to add a new variable to the list. This will bring up the Statistics dialog.

The Variable is selected from the Object Tree, a Criterion Level is set and the resolution of a probability distribution (if being collected) is defined.

The Criterion value can be either a maximum or minimum above or below which Visualyse Interplanetary will record an event.

The Visualyse Interplanetary Log File

The values of any number of variables can be saved to a Log file at time intervals that are user definable. The log file has the same name as the simulation file and is in the same directory. Variables can be added to the file at the start of each run by selecting ‘Log Data’ from the analysis menu

A list of currently selected log variables is shown. To add a new variable press ‘Add’ then the data to be logged can then be selected by navigating the Object Tree, to point to the required variable. Note: it is possible to add multiple variables at the same time by holding the “Ctrl” key when clicking.

Data can be logged at each time step or every n time steps, where n is any integer. The logging interval is set via the Configure item of the Run menu.

The resulting log file will contain the values of all the defined variables at each required time interval. The log file can be edited using any text editor. The data in the file is tab delimited and can be imported into other Windows applications such as spreadsheets and word processors.

The example text below is copied from a log file containing two variables, the received power and the antenna elevation at an earth station tracking a non-GSO constellation

The View Results Dialog

The Results dialog provides a way to look at what Visualyse Interplanetary has calculated numerically (see Graphing for details on examining results graphically).

The Results dialog allows you to look at snapshot link budgets at a specific time and also at statistical results collected over the course of a dynamic simulation.

Results seen in the dialog can be copied and pasted, exported or plotted immediately at the press of a button.

Results are presented in terms of Links, Link Groups and Other User Defined Statistics. By default, the results list shows all the results available in the simulation.

The list can be filtered to show just Link Results, Link Group Results or User Defined Statistics results – simply select the option you require in the top left of the dialog (as shown below).

To view a result, select the object of interest and click the View Results button (or double click on the object in the list).

The example below shows what the results may look like for a single link.

The results show the current Calculations on the first page. Details of the Link Budget and any interference are shown. For the Link Budget, details of the route (transmit/receive station antenna and beam), frequency, EIRP, losses and gains are list.

The small cross to the left of any entry in the Calculations page indicates substructure and clicking the cross will expand the item.

The dialog will also include a tab for each type of statistic being collected. The tab will show current statistical information on the parameter named at the top of the tab.

Statistical values given are:

• The worst value
• The average value
• The standard deviation

If some of the values show interference in excess of the defined criterion, the dialog will also show:

• The number of exceedance events
• The % time that the threshold was exceeded
• The longest single event
• The average event length

The probability distribution of the statistics is shown in a grid at the bottom of the dialog. You can copy this grid for further processing and you can plot a cumulative distribution (on an Analysis Graph) by just pressing the plot button at the bottom right.

Graphing

There are three types of graph available in Visualyse Interplanetary:

• Data vs. Time Graph - time stepped interactive plot of a variable against time
• Data vs. Data Graph - the display of any two variables on an XY scatter plot.
• Distribution Graph - the display of probability distributions, and cumulative distributions for interference and user defined statistics.

Graphs are created from the Results menu or from the toolbar icons:

All graphs can be configured via the Chart Settings dialog, invoked by a right mouse click on the graph area, or from the 'Properties' option of the View menu item

Data vs. Time

A Data vs. Time graph allows up to six variables in the simulation to be watched as they evolve with time. The Data vs. Time graph dialog can be invoked by selecting the Data vs. Time graph item from the Analysis Menu, or by a mouse click on the Data vs. Time graph icon, , on the main toolbar.

The Data vs. Time graph definition dialog is shown below.

The number of time steps to be displayed can be changed in the top left of the dialog. The default is 50; the upper limit imposed by Visualyse Interplanetary is 1000.

An option to automatically scale the Y-axis can be selected at the top right of the dialog. This will continually adjust the Y axis range, based on the range of data values in the plotted data set.

If the automatic axis scaling option is not chosen, the minimum and maximum expected values must be specified. These default to values that depend on the type of variable to be plotted and on the current value of that variable. For example, in the case of C/I 60 dB is considered to be a reasonable range. If Data vs. Time graph is invoked when the value is 25 dB, the default maximum and minimum expected values will be 55 B and -5 dB.

The best option here is for the user to define maximum and minimum expected values based on experience or an understanding of the problem.

The ‘Set Markers’ button allows markers or lines to be added to graphs at defined fixed points. On a Data vs. Time graph this can be used to add a line at a reference, threshold value, as shown in the example below.

Up to six variables can be simultaneously plotted. Select the number of plots required then set the variable for each plot via the ‘Set Plot n’ button.

To select the variable to be plotted, click the ‘Set Plot’ button. You can then choose to plot Link parameters, or any other variable selected from the simulation object tree.

Interference parameters (C, I, N, C/I etc.) can be chosen for each defined Link (or Link Group), by highlighting the Link (or Link Group) name in the list on the left, and double clicking the variable on the right.

Other parameters can be chosen by clicking the ‘Select Variable’ button using the standard variable selection dialog.

See Configuring Graphs for details of how to set the display properties of the Data vs. Time graph.

Data vs. Data Graph

The Data vs. Data graph can be used to display up to three pairs of variables on a scatter plot. An example would be to plot an antenna azimuth and elevation on the same graph for a tracking antenna. Handover of the Link to another station would appear as a discontinuity on the plot.

The Data vs. Data graph dialog is invoked by selecting Data vs. Data graph from the Analysis menu, or clicking the Data vs. Data graph icon, , on the toolbar.

The ‘Number of time steps’ to plot and the ranges to use for each axis are inputs. The axes ranges can be automatically selected based on the range of values in the data set at each time step. If the Auto Scale option is not chosen the maximum and minimum required values need to be specified

Parameters of each plot are selected via the ‘Set Plot’ button. This brings up the Select Variable box (below)

Interference parameters (C, I, N, C/I etc.) can be chosen for each defined link (or link group), by highlighting the link (or link group) name in the list on the left, and double clicking the variable on the right. Other parameters can be chosen via the ‘Select Variable’ button, which brings up the object tree.

Distribution Chart

The Distribution chart option is used to plot probability distributions and cumulative distribution functions for up to six interference parameters or user defined statistics for which histogram bin data is being calculated.

The Distribution option is invoked by selecting Distribution from the Analysis menu or by clicking the Distribution icon on the toolbar.

The dialog allows any defined statistical variable to be selected.

Select either ‘Probability Distribution Function’ or Cumulative Distribution Function’ in the top left of the dialog, depending on the graph type you want. The default CDF shows the cumulative distribution as a line graph.

Further plots can be selected at this stage. Up to six variables can be simultaneously plotted. Select the number of plots required, then set the variable for each plot via the ‘Set Plot n’ button.

Markers can also be added using the Set Markers button.

The example below shows three curves of C/I, C/N and C/N+I.

Example Distribution Chart

The Select Statistics dialog is shown below. Interference parameters (C, I, N, C/I etc.) can be chosen for each defined Link (or Link Group), by highlighting the Link (or Link Group) name in the list on the left, and double clicking the variable on the right. Other variables are chosen from the list of user defined statistics on the right.

Configuring Graphs

If after creating a graph you want to change the data set used, then you can change it by selecting menu option Edit | Plot data.

All graphs can be configured via the Chart Settings dialog, invoked by a right mouse click on the graph area, or from the 'Properties' option of the View menu item. This tabbed dialog is used to configure and customise graph styles, titles, data markers etc.

The options available on each tab are briefly explained.

Titles

The colour and font styles can be set for the graph title, and X-Axis and Y-Axis labels.

The legend can also be configured on/off and have its position defined.

X-Axis

X-Axis properties, colours, styles and tick marks are defined here.

Y-Axis

Y-Axis properties, colours, styles and tick marks are defined here.

Data

This page allows the data being plotted to be changed.

Copying Graphs and Data

Like most views you can copy the graph to paste into other applications like Microsoft Word and Excel. Note it might be necessary to use those application’s Paste | Special option to select the format that is most suitable.

In addition, it is possible to export the raw data using the menu option “File | Export plot data”.

Area Analysis

Visualyse Interplanetary includes a powerful feature for area analysis that is both quick and simple to use.

Area Analysis allows you to produce colour coded block plot or contours of Link or Station parameters and of the statistics of these parameters.

In outline, you simply define the area you are interested in and Visualyse Interplanetary will ask for a template Link (or Station) to use as a test probe at every point (down to a user defined resolution) within the area to work out the parameter you want to analyse.

There is also an alternative method called “Advanced Contouring” to produce contours using groups of stations and links as described in the last sub-section.

• Area Analysis
  • Creating the Analysis
  • Area Analysis Plot Options
  • Display Settings
    • Block Plot Display Settings
    • Contour Display Settings
  • Area Analysis Pop-Up Menu
  • Area Analysis Management and Display
  • Advanced Contouring using Groups

Creating the Analysis

Area analysis is started by selecting ‘Create and Area Analysis’ from the Results menu or clicking the icon on the toolbar, or by selecting the Area Analysis Manager from the Results menu.

The simplest way to create a new Area Analysis is to click the icon - you can then draw out the area on the map using the mouse. Drag the mouse from the top left to the bottom right of the area of interest.

When you release the mouse you will be prompted to select a Link to use as your template, and will have to select the parameter to analyse, as in the figure below.

The Area Analysis properties page has the following parameters:

• Name
• Coordinates – if you have defined the area by drag and drop, the coordinates of the corners will be shown here and can be edited
• Moving station – one station must move in over the defined area. If you are looking at something like coverage analysis, this Station will be the receive station. If you are looking at interference levels it would be victim station. If you are looking at exclusion zones, it would probably be the interfering station.
• Plot parameter – select here the variable to be displayed in the Area Analysis for each location of the moving station
• Adjustment during run – this allows the field to display to take account of the simulation run, so that either the value for the current time step at each time step is shown or the min / max / mean over all time steps at each point is shown.
• Plotting options – as described in the following section
• Control to suspend drawing at each simulation update (including time step) to improve performance
• Control to suspend drawing of the Area Analysis title bar.

You can re-size the Area Analysis by clicking on the “Select Mode” icon on the toolbar and then dragging and dropping one of the corners or edges of the Area Analysis Rectangle.

Area Analysis Plot Options

You can plot the area analysis as a grid of coloured blocks (block plot) or as a series of contours (contour plot). Examples of these are shown below.

The number of kilometres between test points defines the resolution of the analysis. You can set this from the dialog.

Display Settings

The display settings depend on the type of plot you select.

• Block Plot Display Settings
• Contour Display Settings

Block Plot Display Settings

A block plot shows the variation in the chosen link parameter by plotting a block of colour at each test point. The display settings allow you to determine how the blocks are coloured, what ranges to plot and how the plot is rendered. The Display Settings dialog is shown below.

You can press the ‘Add’ button to add new levels and then:

• Type in the value in the first column
• Select the colour from the colour select control at the top right.

The left side of the dialog shows a preview of how the colours will appear on your plot. Calculated results between value entries in the table will result in a colour blended between the nearest two colour entries.

There is also a field to enable display of a legend on the map offset to one side of the Area Analysis, as in the figure below showing example file “PMR Coverage” from the “Network Coverage” example files.

Colour Selection Tip 1: to create a map from ranges of values to a single colour, include two entries, one for the start and end of the required range. So in the example above yellow is used for C/Ns between 5 and 10. The first is offset slightly to 5.1 so it is greater than the end of the previous range, which is that C/Ns between -10 and 5 should be in red.

Colour Selection Tip 2: it is possible, and often useful, to set colour as “Don’t draw”. This can be useful to show in colour where criteria such as coverage is met and no colour where there is no coverage.

Contour Display Settings

Contour plots show the variation of the link parameter across the area as a set of contours. Because there are only a discrete number of contours, you can set their levels and colours individually. The display settings dialog for contour plots is shown below.

You can show up to ten different contour levels on your plot. These are shown on the left of the dialog. To set the level for a particular contour, simply enter a value for it in the appropriate box.

To change the line style or colour of a particular contour, click on the line style control.

You can switch off contours by clicking on the appropriate check boxes.

If you want to display several contours between two levels, set the top and bottom contour levels to the extreme values and click “Space levels evenly” to automatically set the levels for the contours in between.

If you are not sure what the likely range of values will be in your plot, click “Suggest levels”. This will establish the likely range of values and fill in the contour levels with suitable values.

You can choose whether to show a label for each contour. The font for the contour labels can also be changed.

You can save your contour settings as schemes for use another time. A number of schemes are supplied with the software. The values at the levels are not saved as these are highly dependent on the individual plot.

Area Analysis Pop-Up Menu

There are additional controls in a pop-up menu: to activate this right click on the Area Analysis.

This gives additional options for the Area Analysis including:

• Export data: save the data as a comma separated values (CSV) text file for additional analysis
• Export population data: save in CSV format the population associated with each of the contour or threshold levels defined under Area Properties. This requires the population data directory be set as in Population Data Settings
• Bitmap: saves the image produced by the Area Analysis as a bitmap
• KML: exports data from the simulation including the Area Analysis to be displayed in Google Earth (see Interface to Google Earth)
• Delete: deletes the selected Area Analysis
• Suspend on/off: stops re-calculation of the Area Analysis every time the simulation is updated. This is useful for calculations that take a long time to complete. Remember to un-suspend to show the results!
• Area Properties: opens the Area Analysis configuration dialog as described in Creating the Analysis
• View Properties: opens the view configuration dialog as described in Map View

Tip: It is often useful to create Area Analysis that do not completely overlap so that it is possible to right click on each to open this list of options. However remember the Area Analysis Manager (see following section) can be used to open the properties of any Area Analysis – even those covered by others.

Area Analysis Management and Display

All the Area Analysis defined for the current simulation can be accessed via the Area Analysis list, accessed via the Results menu option “Area Analysis Manager”.

The dialog allows control on the Area Analysis, including buttons to:

• Add
• Edit
• Delete
• Duplicate

Any of the Area Analysis can be shown on any map or 3D view where they are controlled via the overlays tab on the view properties: see Overlays for more information.

Advanced Contouring using Groups

This section describes an alternative way to generate contours using a grid of stations and associated links.

It is accessed via the properties dialog of:

• Map Views (Mercator or Plate Carrée)
• 3D View

On the view properties dialog on the first or “Features” tab there is an “Options” button under “Advanced Contouring”. If you click on this you will be able to configure the contours using the following two pages:

To make this form of contouring work you must:

1. Create a grid of test points using the Station Group Service Area Wizard. This can define the service area by {Region, Beam footprint, or Country} but not {Locations or Hexagonal Cells}. On the final page the option selected must be to fill the area with stations in a grid defined by a number (North, East).
2. For each of these stations create a link using the “Link to Station Group” Wizard. Often this is a Receive Link but it could be Fixed Link or even under some circumstances a Dynamic Link. However, it cannot be a Transmit Link.
3. Configure the rest of the simulation including any other stations, links and interference paths.

Having done these three steps there will be a Link Group which has an associated station (either the start or end station) which is one of a grid of test points. It is therefore possible to associate a value from any of the link calculated values for each point on that grid and then contour it.

It is often useful to check that the values are as expected for one or two links using the standard Watch window.

When the simulation has been configured, it is possible to define the contours to display using the two dialogs above. This is done in two stages:

4. Define the Data to Contour

   The data to contour is defined using the “Contour Definition” dialog shown in the figure above, and consists of:

   • Select of group to use: this is usually a link group which have stations at one end that are in a regular grid
   • Select whether to display a Station attribute (such as elevation or azimuth angles) or Link attribute (many of them, including C, I, C/I, C/(N+I), I/N etc)
   • Select the object and variable from it to display: this is similar to the selection of a variable in the Watch window.
   • Select the link direction (either Forward = Start to End or Return = End to Start) and then whether the grid of test points is the transmitter or receive station for the selected link direction.

   It is also possible to define a minimum distance: this feature could, for example, be used to define a minimum coordination distance for Mode 1 or Mode 2 contours derived using RR Appendix S.7.

5. Define how the Data is to be Displayed

   The contour levels and labelling is selected using the “Contour Display” dialog shown in the figure above.

   This dialog is similar to the controls used to select beam or link levels on the view properties dialog.

   Area Analysis vs Advanced Contouring

   In general the Area Analysis tool is much more flexible and results in smaller simulation files that are quicker to load.

   There are a few cases where it can be more useful to use the Advanced Contouring option. One is shown in the figure below, where by the grid of test points are all within the area defined by a polygon (in this case France) rather than a square that could include other countries or the sea.

In this example a grid of test points with France has been used to generate a contour of locations where a 50 dBW transmitter at a height of 100 m would just meet a PFD threshold on the sea or land boundaries of France.

Interface to Google Earth

There are two places in Visualyse Interplanetary where provides an interface to Google Earth. The first is on the File menu, the second is via the pop-up menu you get if you right click on any of the map or 3D views.

Export items using File Menu Option

When a 2D or 3D map views is active, the File menu gives you the option to ‘Export to Google Earth …’.

Click on this option and the following dialog appears:

You can selective export all the Advanced Contours, Area Analyses, Beams, Links and Station Icons (together with their locations) from the current simulation.

Define the file location and Visualyse Interplanetary produces a .KMZ file: by default this will be in the same location as the sim file.

If the final box is checked, Google Earth will be launched automatically when the file export is complete (assuming it has been installed).

Export items using Pop-up Menu

If you right click on either of the map views or the 3D view outside of an Area Analysis, you will get a pop-up menu as shown below:

If you select “Export to Google Earth…” you will get the same dialog as above, and can use that to create a KMZ file and start Google Earth automatically.

If you right click on either of the map views or the 3D view inside of an Area Analysis, you will get a pop-up menu as shown below:

There is an option here, “KML”, that allows you to generate the KML file that can be used later by Google Earth.

Managing Data within Google Earth

Google Earth allows you to view your data in 3D overlaid upon standard geographical information including satellite photos, roads, railways etc.

For example if you export the demonstration file “PMR Coverage.sim” from the “Network coverage” directory, Visualyse Interplanetary will export:

• Two stations, the base station and the mobile station
• One Area Analysis, showing the predicted C/N

These are grouped together in a tree, and each item can be shown or hidden within Google Earth by clicking on the check box, as in the figure below:

Google Earth can then display the required images, such as:

Background on Google Earth

More information about the features and background to Google Earth including downloads can be found at:

http://earth.google.com/

A number of versions are available which at time of press included one free to use for non-commercial usage and another requiring minor fee for commercial use.

Note that the functionality and licensing of Google Earth could be modified by Google in the future.

Question: Why are Google Earth files called KMZ?

Answer: The program is based upon tools used to view images generated by the Keyhole satellite program, and a Markup languages was created to add overlays. In addition the files are Zipped to reduce their size.

Acronyms and Abbreviations

Introduction

The aim of this section is to give users of Visualyse Interplanetary a better idea of the algorithm it uses and hence a deeper understanding of the results generated and which options should be selected.

It covers key elements of how Visualyse Interplanetary works, including:

• Update sequence
• Coordination systems
• Link budget calculations
• Gain patterns
• Propagation models
• File formats
• VisTools calculations
• Acronyms and Abbreviations

This section should be read in conjunction with the other guides provided, in particular the:

• User Guide: this describes how to use the product including all the dialogs
• Tutorial: this gives a walk-through of the steps required to create an example simulation
• Maintenance History: this gives information on changes released under the Annual Maintenance and Support (AMS) service
• Demonstration Files: this describes the example files shipped with Visualyse Interplanetary and gives an indication of the types of simulations it can generate

Additional Technical Notes and White Papers can be found on our web site at:

https://www.transfinite.com/papers

Note: In places the description of the algorithm used has been simplified to make it clearer and to protect elements of Transfinite’s Intellectual Property Rights (IPR)

Update Sequence

This section describes the series of steps Visualyse Interplanetary uses to update the simulation at each time step. This well-defined procedure ensures the results generated by Visualyse Interplanetary are always consistent with the input parameters selected.

The process is as follows:

1. Update the current time using time step information
2. Set the random number seed for this time step
3. Update all the define variables
4. Update all the positions of the stations
5. Update the pointing of each antenna (except if pointing by link)
6. Update all links including:
   • Calculating the traffic profile for this link for this time step
   • Selecting the station, antenna, beam to use for dynamic links
   • Updating the pointing of any antenna that uses pointing by link
   • Calculating the wanted signal level
   • Updating the wanted signal calculation if using power control
7. Updating all interference paths
8. Updating all link groups
9. Update all statistics
10. Updating all views and outputting to file any information requested to be logged

Coordination Systems

This section defines the coordinate systems used for each type of station and within antennas and beams.

• ECI Vectors
• Terrestrial Stations
• Satellite Orbits
• Station Coordinate Systems
• Station, Antenna and Beam Coordinate Systems
• Slice Angle

ECI Vectors

All stations in Visualyse Interplanetary are located in Earth Centred Inertial (ECI) coordinate system using position and velocity vectors of the form:

$$r=\left(\begin{array}{l}x\\ y\\ z\end{array}\right)$$

The co-ordinate system is defined as follows:

X axis: aligned with the vernal equinox as described further below

Z axis: aligned with the North Pole

Y axis: at right angles to the X and Z axes, using right handed co-ordinate system

The X axis of the ECI system is oriented in relation to the earth using the first point of Aries at the following epoch:

At: 00:00 hours on the 1st January 1970

$${\theta }_{g_0}=100^{\circ }229421$$

This is shown in the figure below:

The frame of reference of the earth rotates at the following rate:

$${\theta }_g={\theta }_{g_0}+\omega t$$

Where:

$\omega$ is the angular rotation rate of earth in radians / second

$\mathrm{t}$ is time in seconds since reference time

Terrestrial Stations

Stations on the surface of the Earth are defined via their (latitude, longitude, height) which is converted into an ECl vector using:

$$\underline{r}=R\left(\begin{array}{c}\cos (lat)\cos \left({\theta }_g\right)\\ \cos (\text{ lat })\sin \left({\theta }_g\right)\\ \sin (\text{ lat })\end{array}\right)$$

Where:

$R=$ Radius of the Earth $\left(R_e\right)+$ height of station above smooth Earth (h)

Lat $=$ Latitude of the station

${\theta }_g=$ the conversion of the longitude in the rotating Earth frame to angle with respect to the $X$ axis.

Stations with non-zero speed will have their (latitude, longitude, heights) updated assuming they take great circle paths over a spherical Earth.

Satellite Orbits

• Orbit Parameters
• Orbit Models
• Orbit Conversions

Orbit Parameters

Within Visualyse Interplanetary a standardised set of orbital elements are used, namely:

These parameters are shown in the figures below.

Orbit Models

Two orbit models are including in Visualyse Interplanetary:

• Point mass
• Point mass plus $J2$ term

The $\mathrm{J}2$ orbit model to update a non-GSO satellite at time $\Delta \mathrm{t}$ is calculated from the orbit elements as follows:

$$\begin{array}{rl}& \mathrm{a}={\mathrm{a}}_0\\ & \mathrm{e}={\mathrm{e}}_0\\ & \mathrm{i}={\mathrm{i}}_0\\ & \omega ={\omega }_0+{\omega }_r\Delta t\\ & \Omega ={\Omega }_0+{\Omega }_r\Delta t\\ & M=M_0+\left(\bar{n}+n_{\text{user }}\right)\Delta t\end{array}$$

Where:

${\omega }_0:$ perigee argument at an initial moment

${\Omega }_0:$ ascending node longitude at an initial moment

${\mathrm{M}}_0:$ mean anomaly at initial moment

${\mathrm{n}}_{\text{user: }}$ additional, user entered, precession (defaults to zero)

And:

${\omega }_r:$ perigee argument precession rate

${\Omega }_r:$ ascending node longitude precession rate

$\bar{n}:$ rate of change of mean anomaly

These are calculated from the following:

$$\begin{array}{rl}& {\omega }_r=\frac{3}{2}\frac{J_2{R}_e^2}{p^2}\bar{n}\left(2-\frac{5}{2}{\sin }^2(i)\right)\\ & {\Omega }_r=-\frac{3}{2}\frac{J_2{R}_e^2}{p^2}\bar{n}\cos (i)\\ & \bar{n}=n_0\left(1+\frac{3}{2}\frac{J_2{R}_e^2}{p^2}\left(1-\frac{3}{2}{\sin }^2(i)\right){\left(1-e^2\right)}^{1/2}\right)\end{array}$$

where:

$$\begin{array}{rl}& p=a\left(1-e^2\right)\\ & J_2=1.083e-3\\ & n_0=\sqrt{\frac{\mu }{a^3}}\end{array}$$

Orbit Conversions

Some orbits are defined using other parameters, such as apogee / perigee height or radii. These can be converted into the standard set above using the following equations.

Elliptical orbit shape

The apogee / perigee heights / radius's can be converted using:

Apogee conversion: $R_a=R_e+h_a$

Perigee conversion: $R_p=R_e+h_p$

${\mathrm{R}}_{\mathrm{e}}$ is the Earth's radius of $6378.1\mathrm{km}$.

Then the semi major axis and eccentricity are:

$$\begin{array}{rl}& R_a=a(1+e)\\ & R_p=a(1-e)\end{array}$$

So:

$$\begin{array}{rl}& a=\left(R_a+R_p\right)/2\\ & e=\left(R_a-R_p\right)/\left(R_a+R_p\right)\end{array}$$

Anomaly Angle

There are a number of ways of defining where the satellite is in the orbit plane with respect to the perigee, including

$$\begin{array}{rl}& v=\text{ true anomaly }\\ & E=\text{ eccentric anomaly }\\ & M=\text{ mean anomaly }\end{array}$$

These are related using:

$$\begin{array}{rl}& \cos E=\frac{e+\cos v}{1+e\cos v}\\ & \cos v=\frac{e-\cos E}{e\cos E-1}\\ & M=E-e\sin E\end{array}$$

The last equation can be used together with iteration to calculate $E$ from $M$.

Elapsed time is related to $M$ using:

$$M=n\Delta T$$

where $n$ is the mean motion:

$$n=\sqrt{\frac{\mu }{a^3}}$$

where $\mu =3.986012\mathrm{e}5{\mathrm{km}}^{\wedge }3/{\mathrm{s}}^{\wedge }2$ is the gravitational constant

Anomaly Angle

There are a number of ways of defining where the satellite is in the orbit plane with respect to the perigee, including

$$\begin{array}{rl}& v=\text{ true anomaly }\\ & E=\text{ eccentric anomaly }\end{array}$$

$M=$ mean anomaly

These are related using:

$$\begin{array}{rl}& \cos E=\frac{e+\cos v}{1+e\cos v}\\ & \cos v=\frac{e-\cos E}{e\cos E-1}\\ & M=E-e\sin E\end{array}$$

The last equation can be used together with iteration to calculate $E$ from $M$.

Elapsed time is related to $M$ using:

$$M=n\Delta T$$

where $n$ is the mean motion:

$$n=\sqrt{\frac{\mu }{a^3}}$$

where $\mu =3.986012\mathrm{e}5{\mathrm{km}}^{\wedge }3/{\mathrm{s}}^{\wedge }2$ is the gravitational constant

Station Coordinate Systems

The coordinate system used by the station defines how the antennas are pointed and varies between station types.

• Calculation of Azimuth and Elevation
• Fixed Stations
• Non Geostationary Satellites
• Geostationary Satellites
• Moving Stations

Calculation of Azimuth and Elevation

For each station type an intermediate local set of orthogonal vectors, (X’, Y’, Z’) are generated. From these the azimuth and elevation are calculated as follows:

To define the coordinate system for each station type it is therefore necessary to define the ( $X^{\prime },Y^{\prime },Z^{\prime })$ vectors in each case.

An alternative way of considering it is that for an observer, the azimuth is the angle in the horizontal plane with the line directly ahead, with the right hand being positive, whilst the elevation is the angle in the vertical plane compared to the horizon, with up being positive.

Fixed Stations

For stations at fixed locations, whether Earth, terrestrial, mobile, maritime or aeronautical stations, the azimuth and elevations are derived using the north, east and zenith vectors as shown in the figure below:

Figure Earth / Terrestrial station co-ordinate system

These are mapped onto the generic local vectors as follows:

X’ = E

Y’ = N

Z’ = Z

The result is the traditional alignment of:

• Azimuth = angle in the horizontal plane from due North increasing in a clockwise direction, defined within the range (-180 to +180)
• Elevation = angle above the horizontal plane

Non Geostationary Satellites

For satellites the coordinate system is based upon the line to the centre of the Earth (i.e. towards the sub-satellite point) and the velocity vector, so that for circular orbits:

X’ = Q = vector at right angles to velocity and position vectors

Y’ = P = -R

Z’ = V

The P and Q vectors are shown in the figure below.

Another way of looking at it is to consider the view from the satellite looking down at the sub-satellite point, head pointing in the direction of the velocity vector – the “superhero” position. In this case as in the figure below:

• Azimuth = to left and right of the sub-satellite point, where right is positive
• Elevation = up and down, where up is positive

This coordinate system assumes that the radius vector and velocity vector are at right angles which will only be the case for circular orbits. For elliptical orbits it is necessary to select which vector of (R, V) the coordinate system will align with.

Geostationary Satellites

For satellites the coordinate system is based upon the line to the centre of the Earth (i.e. towards the sub-satellite point), the north vector, and the velocity vector, so that:

Figure 3: Coordinate System for Geostationary Satellites

In formal terms, for a GSO satellite:

X’ = V

Y’ = -R

Z’ = N

Moving Stations

Moving stations can use either of the coordinate systems describe above:

• North based, as for terrestrial stations
• Velocity based, as for non-GSO satellites.

Additional coordinate frames can be created by utilising the orientation (or Euler) angles (pitch, roll, yaw) which define how the antenna platform is located with respect to the station coordination scheme.

For example consider an aircraft, when the orientation is velocity based, where the following Euler angles have been set:

Pitch = 90º

Roll = 0º

Yaw = 0º

This will rotate the az/el = (0, 0) line from the line from the station to the centre of the Earth to the direction of motion. Having done this the azimuth angle is similar to yaw while elevation angle similar to pitch, as in the figure below using a ship as an example:

A similar coordinate system can be used for aircraft.

Note that if the aircraft is pitching up or down the velocity vector will not be at right angles to the position vector. Hence the coordinate frame will have to choose which to align with.

To create a coordinate system in which the reference az/el = (0, 0) remains the nose of the aircraft even when pitching up or down the following settings should be used:

Coordinate System:

Velocity based = true

Align with velocity vector = true

Pitch = 90º

Roll = 0º

Yaw = 0º

Station, Antenna and Beam Coordinate Systems

A station can contain multiple antennas which can contain multiple beams. Each can have its own pointing angles – so for example there can be:

• Pointing angles of antenna with respect to station’s coordinate system (these are the azimuth, elevation of the antenna in the station dialog)
• Pointing angles of beam with respect to antenna’s coordinate system (these are the azimuth, elevation of the beam in the antenna dialog)

In addition there can also be:

• Pointing angles of antenna platform with respect to station (these are the orientation angles on the station dialog’s advanced tab)

These angles are combined together in the following order from inertial ECI vectors:

• From ECI to (azimuth, elevation) in station coordinate system using definition of (X’, Y’, Z’) in previous section
• From station coordinate (azimuth, elevation) to antenna platform (azimuth, elevation) using orientation angles (yaw, pitch, roll)
• From antenna platform (azimuth, elevation) to a specific antenna’s (azimuth, elevation) using the antenna’s az/el pointing angles
• From an antenna’s (azimuth, elevation) to a beam’s (azimuth, elevation) using the beam’s az/el pointing angles

Slice Angle

This section describes the definition of the slice angle which is used within Visualyse Interplanetary to display gain patterns.

For many antennas, such as those using parabolic reflectors, the gain pattern is symmetric around the boresight. The gain pattern can therefore be displayed in a graph as gain vs offaxis angle – for example the pattern below is Recommendation ITU-R Rec. S.465 for a 2.4m dish at 3.6 GHz:

Other antennas do not have this symmetry: for example the patterns of a base station antenna are likely to vary in both azimuth and elevation, and hence are described as 3D patterns.

For these antennas the gain pattern taken in the azimuth and elevation directions are likely to be different, and we call these different directions “slices”. The slices are taken in planes that intersect the boresight line (see figure at top).

The orientation of the slice is defined by the slice angle or , which is the angle of the slice plane to the elevation = 0 plane. Hence the = 0 slice is the gain pattern in the azimuth plane while the = 90 slice is the gain pattern in the elevation plane.

Rather than showing offaxis angle along the X axis of the gain plot, the slice instead shows the angle from the boresight line, shown in the figure above as .

Any slice angle can be selected from 0 to 180 and it will define a plane and hence create a separate gain pattern. As all slices intersect the boresight line all will start with the = 0 point which is the boresight, usually, but not always, defined as the point in the 3D gain pattern with highest gain value.

For example the figures below show two slices from the same 3D gain pattern and hence start with = 0 where the gain = 18 dBi.

Slice angle = 0 (azimuth plane)	Slice angle = 90 (elevation plane)

Note that azimuth and elevation in this figure are relative to the gain pattern’s boresight and there could be a variety of orientation angles including:

• Beam within the Antenna Type
• Antenna with respect to the Antenna Platform
• Antenna Platform with respect to the Station

Note also there are a variety of Station orientations as described in the previous sections.

Link Budget Calculations

• Power Calculation Reference Points
• Noise Calculation
• Other Parameters
• PFD and Field Strength
• Interference Adjustments
• Link Group Calculations
• Modelling Radar Reflections
• Listen before transmit

Power Calculation Reference Points

In order to be able to model a wide range of radio systems a generic link model is used in all calculations in Visualyse Interplanetary. The basic link budget is as follows:

$${\mathrm{C}}_{\mathrm{RX}}={\mathrm{P}}_{TX}+{\text{ GPeak }}_{TX}+{\mathrm{GRel}}_{TX}-L_P+{\text{ GPeak }}_{RX}+{\text{ GRel }}_{RX}-L_{RX}$$

Where:

$P_{TX}=$ transmit power at input to antenna (dBW)

GPeak ${}_{\mathrm{TX}}=$ transmit antenna peak gain $(\mathrm{dBi})$

GRel ${}_{Tx}=$ transmit antenna gain towards the receiver relative to peak (dB)

$L_P=$ propagation loss between transmit and receive antennas (dB)

GPeak ${}_{\mathrm{Rx}}=$ receive antenna peak gain $(\mathrm{dBi})$

GRel ${}_{\mathrm{Rx}}=$ receive antenna gain towards the transmitter relative to peak $(\mathrm{dB})$

$L_{RX}=$ losses between receive antenna and input to the receiver $(\mathrm{dB})$

The reference points are therefore:

Transmitter: at the input to the antenna

Receiver: at the input to the receiver

Hence there is no field in Visualyse Interplanetary for the transmit line loss.

The reference points for the link budgets are therefore as shown in the figure below:

Note that:

$$\begin{array}{rl}& {\mathrm{G}}_{\mathrm{TX}}={\mathrm{GPeak}}_{\mathrm{TX}}+{\mathrm{GRel}}_{\mathrm{TX}}\\ & {\mathrm{G}}_{\mathrm{RX}}={\mathrm{GPeak}}_{\mathrm{RX}}+{\mathrm{GRel}}_{\mathrm{RX}}\end{array}$$

The receive measurement point can be made to be at the output of the receive antenna by setting the LRX to zero.

Noise Calculation

In Visualyse Interplanetary there are two ways to define the noise at the receiver:

• Enter the noise temperature of the receiver directly
• Allow Visualyse Interplanetary to calculate the receiver noise temperature from the various components.

The calculation of receiver input noise is based upon the following parameters:

The system temperature is calculated from:

$$T_{\text{sys }}=\frac{T_{\text{ant }}}{L_{\text{feed }}}+T_{\text{feed }}\left(1-\frac{1}{L_{\text{feed }}}\right)+T_{rx}$$

Where:

${\mathrm{F}}_{\mathrm{rx}}=$ noise figure of receiver

${\mathrm{T}}_{\text{ant }}=$ noise temperature of antenna

${\mathrm{L}}_{\text{feed }}=$ feeder loss

${\mathrm{T}}_{\text{feed }}=$ feeder temperature

$T_{rx}=\left(F_{rx}-1\right)\ast T_{ref}$ where $T_{ref}$ is 290 Kelvin

Converted to noise spectral density this is:

$$N_{\text{sys }}=k+10{\log }_{10}T\text{ where }\mathrm{k}=-228.6\text{ is Boltzman’s constant in }\mathrm{dB}$$

Other Parameters

There is a wide variety of methods to define link budgets and these can use different parameters that might need to be mapped onto Visualyse Interplanetary fields.

• Transmitter losses: losses such as transmit link losses can be modelled by reducing the transmit power accordingly.
• G/T: Some antennas have their performance defined via their G/T. In this case it is necessary to determine separate G and T figures to be entered into the link budget above.
• Pointing losses: At the transmit side these can be modelled either by reducing the transmit power according to the required level of pointing loss or by adding a slight offset to the antenna pointing angles. At the receive side the pointing loss could be modelled as either being part of the receiver losses or adding a slight offset to the antenna pointing angles.
• Polarisation losses: These can be included by either adding them to the receive feed loss or adjusting the required C/N or C/(N+I) threshold upwards.
• Baseband losses: losses such as implementation losses, demodulation margin etc can be modelled by adjustment of the threshold required.

PFD and Field Strength

In Visualyse Interplanetary the PFD calculation assumes free space path loss, hence it is simply:

$$pfd=\frac{EIRP}{4\cdot \pi \cdot d^2}$$

It is sometimes useful to derive the PFD assuming the other propagation models within Visualyse Interplanetary’s library. In this case it is possible to calculate the signal (wanted or interfering) as received at an isotropic receiver and convert into either PFD or field strength.

The conversion factors in the case of interference is:

$$pfd=I+10\log \left[\frac{4.\pi }{{\lambda }^2}\right]$$

Note that $\mathrm{c}=\mathrm{f}\lambda$ and that $\mathrm{c}=2.997\mathrm{e}8\mathrm{m}/\mathrm{s}$

To convert the pfd into field strength use:

$$\text{ Field strength }\mathrm{dB}\mu \mathrm{V}/\mathrm{m}=\mathrm{pfd}+145.8$$

Interference Adjustments

• Carrier Overlap
• Frequency Overlap
• Interference Calculation Adjustment
• Frequency Dependent Adjustment
• Polarisation Adjustment
• Mask Integration to derive NFD

Carrier Overlap

It should be noted that all unless masks are given, carrier spectre are assumed to be square with the following parameters defined:

• Central frequency
• Occupied bandwidth
• Allocated bandwidth

Typically the wanted and interfering signals have different central frequencies and / or bandwidths. It is therefore necessary to consider how to adjust the interference calculation to take account of bandwidth factors. The figure below shows a typical situation:

The overlap algorithm is:

$$\begin{array}{rl}& {\text{ Start }}_A={\text{ Freq }}_A-{\mathrm{OBW}}_{\mathrm{A}}/2\\ & {\text{ End }}_A={\text{ Freq }}_A+{\mathrm{OBW}}_{\mathrm{A}}/2\\ & {\text{ Start }}_B={\text{ Freq }}_B-{\mathrm{OBW}}_B/2\\ & {\text{ End }}_B={\text{ Freq }}_B+{\mathrm{OBW}}_B/2\end{array}$$

Then using the start and end frequencies above:

$$\begin{array}{rl}& \text{ StartOverlap }=\max \left({\text{ Start }}_A,{\text{ Start }}_{\mathrm{B}}\right)\\ & \text{ EndOverlap }=\min \left({\text{ End }}_A,{\text{ End }}_{\mathrm{B}}\right)\end{array}$$

So:

$$\text{ Overlap = EndOverlap }-\text{ StartOverlap }$$

This is used in the two bandwidth calculations: whether to include the carrier as being partially co-frequency and how much energy from the interfering carrier to include.

Frequency Overlap

An interfering carrier is included in the interference calculation if at least one of the following is true:

• the overlap between carriers (as calculated above) is greater than zero
• the force co-frequency flag is set

Interference Calculation Adjustment

If there is overlap between two carriers, then it is necessary to determine how much energy to include. Three alternatives are available, and the result is the BWF factor which is used to multiply the interfering carrier level to get the resulting interfering level I.

No Adjustment

In this case the BWF is always 1.

Spectral Power Density

In this case the ratio of the two is used, based on the power spectral density:

$$\text{BWF}=\frac{OB{W}_W}{OB{W}_I}$$

Overlap

In this case the extent of overlap is used, calculated using:

$$\text{BWF}=\frac{\text{ Overlap }(\text{ Carrier }W,\text{ CarrierI })}{{\mathrm{OBW}}_I}$$

Note that for the force co-frequency case the frequency of both carriers is set to the same and ${\mathrm{OBW}}_{\mathrm{W}}\le {\mathrm{OBW}}_1$, and so this becomes the same as Spectral Power Density.

Multiple Carriers

In this case it is assumed that there could be multiple interfering carriers in the bandwidth of the wanted signal. Each interfering carrier is separated by its ABW, but occupies only the OBW. This is shown in the figure below:

Figure Multiple Interferers Into Wanted Carrier

The calculation is therefore:

Frequency Dependent Adjustment

The bandwidth adjustment in the tables above is based upon rectangular blocks of frequency. Some carriers are shaped, such as TV, and so the interference to/from one of these carriers will depend on the separation between central frequencies.

This can be included in the link calculation using a table of advantage vs offset of central frequencies. Linear interpolation is used between entries in the table, with no extrapolation at the ends of the table.

Polarisation Adjustment

Polarisation adjustment can be done one of three ways:

1. no adjustment
2. standard ITU adjustment table
3. user defined table

The tables give constant adjustments based on wanted and interfering carrier polarisations. The user defined table allows checking for main beam to main beam alignment. This occurs when the transmit and receive relative gains are -3 dB or higher.

Note that it is possible in Visualyse Interplanetary to do full cross-polar gain pattern calculations by entering the cross-polar values for one system (typically interfering) and using the co-polar gain pattern for the other system (typically wanted). This can be done using the table patterns.

Mask Integration to derive NFD

In Visualyse Interplanetary it is possible to specify the following two masks:

1. The transmit mask is defined as the relative power density compared to in-band: in other words as a table it would be defined in dB while in the integration the units would be an absolute ratio.
2. The receive mask is defined as the relative attenuation of the receive signal compared to in-band: in other words as a table it would be defined in dB while in the integration the units would be an absolute ratio.

Both the transmit and receive masks are defined using tables with linear interpolation in dB between each point and hence can be modelled as a set of straight lines with equation (in dBs):

$$\begin{array}{rl}& y_{tx}=a_{tx}+b_{tx}f\\ & y_{rx}=a_{rx}+b_{rx}f\end{array}$$

In which case the NFD is:

$$NFD=\sum _{f_{\min }}^{f_{\max }}NFD\left[f_1,f_2\right]$$

Where:

$$NFD\left[f_1,f_2\right]=\frac{10^P}{Q^{\prime }}\left(e^{Q^{\prime }{f}_2}-e^{Q{f}_1}\right)$$

And:

$$\begin{array}{rl}& P=\left(a_{tx}+a_{rx}\right)/10\\ & Q=\left(b_{tx}+b_{rx}\right)/10\\ & Q^{\prime }=\ln (10)\cdot \left(b_{tx}+b_{rx}\right)/10\end{array}$$

Note that in general the values of $a$ and $b$ are not user entered but are derived from a set of values at specific points, as in the figure below.

Three formats of this integration are available:

Integrate masks (Classic): Transmit and receive masks integrated and then divided by the transmit bandwidth. This is the correct approach if the TX spectrum mask is referenced to the mean in-band density i.e. 0 dB is when the power density = TX power / occupied bandwidth.

Integrate masks (NFD): Transmit and receive masks integrated and then divided by the integration of the transmit mask. This is the correct approach if the TX spectrum mask 0 dBi point is referenced to the peak power density.

Integrate masks (ETSI): Transmit and receive masks are integrated for the specified frequency offset and then divided by the integral of the TX and RX masks when co-frequency. This is the correct approach to be consistent with the methodology in ETSI TR 101 854 and is sometimes called the Frequency Dependent Rejection or FDR. To adjust for different bandwidth carriers the carrier overlap calculation is included in the adjustment as per Interference Calculation Adjustment.

Note on the ${\mathrm{HCM}}^1$ NFD: this is calculated as two terms, called NFD and MD where:

$$NFD=\frac{{\int }_{f_{\min }}^{f_{\max }}{M}_{TX}\left(f_{TX}\right)M_{RX}\left(f_{TX}\right)df}{{\int }_{f_{\min }}^{f_{\max }}{M}_{TX}\left(f_{TX}\right)M_{RX}\left(f_{RX}\right)df}$$

i.e. NFD $=10\log 10$ (OverlapAreaCoFrequency / OverlapAreaActualFrequency)

$$MD=\frac{M{I}_{TX}}{{\int }_{f_{\min }}^{f_{\max }}{M}_{TX}\left(f_{TX}\right)M_{RX}\left(f_{TX}\right)df}$$

Therefore the $\mathrm{MD}=10\log 10$ (TXArea / OverlapAreaCoFrequency)

Hence MD + NFD = 10log10(TXArea / OverlapAreaActualFrequency)

Therefore the total HCM bandwidth and mask integration factor is the same as the "Standard NFD" calculation described above.

Link Group Calculations

• Thermal Additional
• Wanted Signal Phase Addition

Thermal Additional

Thermal addition is used to calculate end to end performance for analogue systems. In this case the link qualities are added using the following formula:

$${\frac{C}{X}}_{dB}=10\log \left[\frac{1}{{\sum }_i\frac{1}{10^{\frac{\left(\frac{C}{X_{i,dB}}\right)}{10}}}}\right]$$

where X could be I, N or (N+I).

Wanted Signal Phase Addition

Some diversity systems use two links and merge the two received signals such that the wanted carriers remain in phase. This changes the phase of the interfering signal, and the following algorithm is used to add the link qualities (note in W not dBW):

$$\begin{array}{rl}& C_W=\sum _i{C}_{i,W}\\ & N_W=\sum _i{N}_{i,W}\\ & I_W=\left|I_{0,W}+\sum _i{I}_{i,W}\cos \varphi \right|\end{array}$$

where $\varphi$ is a random number between 0 and $2\pi$.

Modelling Radar Reflections

One of the most important uses of the electromagnetic spectrum is for radar.

When modelling radar in simulation tools the most important difference from most other types of radio system is that the signal is received after two paths via a passive reflection, as can be seen in the figures below:

The signal strength that is received can be calculated using the standard radar equation (assuming free space path loss):

$$P_R=P_T{G}_T\frac{1}{4\pi R^2}\sigma \frac{1}{4\pi R^2}{A}_{eff}$$

Where:

$$\begin{array}{rl}& {\mathrm{P}}_{\mathrm{T}}=\text{ transmit power }\\ & {\mathrm{G}}_{\mathrm{T}}=\text{ transmit antenna gain }\\ & \mathrm{R}=\text{ range from radar to target }\\ & \sigma =\text{ radar cross section of the target }\\ & A_{\mathrm{eff}}=\text{ effective area of the radar receiving antenna }\\ & {\mathrm{P}}_{\mathrm{R}}=\text{ received signal }\end{array}$$

Radar reflections can be modelled via the Link’s End to Start power option. To enable this option:

• Create the radar station with antenna pointing at the aircraft
• Create the aircraft with the required height and for antenna use an isotropic gain pattern with gain 0 dBi
• Create a fixed or dynamic link with:
  • Start station = radar station
  • End station = aircraft
  • Start to End direction: set the transmit power of the antenna
  • End to Start direction: set the transmit power option to be “radar reflection” and then set the radar cross section to be that of the aircraft and the noise temperature to be that of the radar station, as in the example below:

Having created this link the End to Start’s received power will be the radar station’s wanted signal.

Note that any propagation model could be used, not just free space path loss as in the equations above. In particular it could be appropriate to consider:

• Recommendation ITU-R P.452: this includes the effect of terrain and is considered acceptable for low altitudes
• Recommendation ITU-R P.528: this is designed for air to ground / ground to air links up to a maximum height of 20,000m. It does not include the effect of terrain

Both these propagation models can also include a percentage of time field.

Note that the following are checked by Visualyse Interplanetary:

• The Endstart carrier must be the same as the StartEnd carrier
• The Endstart frequency must be the same as the StartEnd frequency
• The end station must use an isotropic antenna with gain = 0 dBi
• The Startend direction must be enabled

Listen before transmit

Recent developments of cognitive technologies, such as listen before transmit, are allowing a range of new sharing scenarios.

An example of this can be found in the 5 GHz band where Radio Local Area Networks (RLANs) can operate as long as they do not cause harmful interference into radars in the frequency ranges 5 250 - 5 350 and 5 470 - 5 725 MHz. The mechanism used to protect the radars is dynamic frequency selection based upon listen before transmit technologies.

As described in Recommendation ITU-R M. 1652, RLANs with the potential to transmit up to 200 mW e.i.r.p. must be capable of detecting radar signals of -62 dBm. If a signal is detected on a channel then it can not be used and instead the RLAN must try another channel.

This is shown graphically in the figure below:

In regulatory terms there could be a constraint similar to::

System A can only transmit at power = X if the signal received from System B is less than Y

The question is then, what are the relevant values of X and Y? This requires interference analysis taking into account deployment densities and propagation conditions.

This can now be modelled in Visualyse Interplanetary using a bi-directional link (i.e. either fixed or dynamic link) as follows:

• Start->End: model System B’s signal as detected by System A (for example, Radar to RLAN)
• End->Start: model System A transmitting in the signal received on the StartEnd path is below the detection threshold (i.e. the RLAN transmitting)

The End->Start direction can then be used as one of the interferers into System B to determine what the impact would be.

The link options are in the End->Start direction as shown in the figure below:

Gain patterns

• ITU and ETSI Gain Patterns
• Additional Gain Patterns
• Archived Gain Patterns

ITU and ETSI Gain Patterns

• Note on the IMT-MODEL Gain Patterns
• Note on the IMT-MODEL Non-Co-Frequency Gain Pattern

The gain patterns in Visualyse Interplanetary come from a number of sources including:

Table 1: References for ITU-R and ETSI Visualyse Interplanetary Gain Patterns

These documents can be accessed from:

http://www.itu.int

http://www.etsi.org

Registration and/or payment might be required for some documents.

Some patterns are not defined for the full range of offaxis angles. For example ITU-R Rec.S.465 does not define the pattern for offaxis angles less than 1°: in this case it is assumed to be parabolic until reaching the first side-lobe, i.e.

$$G=\max \left[\begin{array}{l}{G}_{\max }-12\left(\frac{\varphi }{{\varphi }_0}\right),\\ 52-10{\log }_{10}(D/\lambda )-25{\log }_{10}{\varphi }_{\min }\end{array}\right]$$

Variations for Recommendation S.465 and S.580 gain patterns extend the pattern using the methodology in the ITU’s Antenna Pattern Library (APL).

Note on the IMT-MODEL Gain Patterns

In order to activate the beamforming of these gain patterns, the antenna type, station and link options should be:

• Antenna type: ensure “Electronically steerable” is checked
• Station antenna pointing:
  • For the BS: set fixed pointing angles
  • For the UEs: point at another station (the BS) using random offsets of azimuth = {-60, +60}, elevation = {-90, +90}
• Link: either a Fixed or Dynamic link from the BS to the UE (or vice versa) to activate the antenna pointing. Note that a transmit or receive link cannot be used

The BS antenna azimuth could also be defined via the Monte Carlo service area Define Variable.

The parameters used to configure this gain pattern take account of the frequency, typically defined in the link.

Note on the IMT-MODEL Non-Co-Frequency Gain Pattern

For antenna types defined by the IMT-MODEL patterns, there are options to select how the gain pattern changes for non-co-frequency interference paths.

The following options are available from the Advanced Beam Options dialog:

• Use co-frequency pattern: the M.2101 pattern is used with D/lambda = 0.5 for both co-frequency and non-co-frequency scenarios
• Single element pattern: the M.2101 single element pattern is used if the victim centre frequency is non-co-frequency
• Assume D/lambda = 0.46: in the M.2101 gain pattern a D/lambda of 0.46 is used rather than 0.5
• Variable D/lambda: it is assumed that at the centre frequency supplied the D/lambda = 0.5, and so for other frequencies the D is derived and fixed but the lambda varies depending upon the victim frequency

The definition of what constitutes “co-frequency” and what “non-co-frequency” for the IMT-MODEL gain pattern is set via:

• Centre Frequency: this is the centre frequency that the IMT-MODEL antenna has been tuned to
• Co-Frequency Bandwidth: this is the total bandwidth that is defined as being co-frequency in range:
  • Minimum = CentreFrequency – CoFrequencyBandwidth./2
  • Maximum = CentreFrequency + CoFrequencyBandwidth./2

Outside this frequency range the interference path is assumed to be non-co-frequency.

To activate these non-co-frequency gain patterns it is necessary to set the Interference Path option:

• Calculate Interfering Signal using Victim Frequency = true

This will use the victim centre frequency when calculating the interfering signal and hence allow the antenna type to identify if the path is co-frequency (to the IMT-MODEL antenna) or non-co-frequency. It will not affect other calculations, in particular the mask integration adjustment or NFD.

Additional Gain Patterns

Other useful gain patterns are:

• Bessel
• Capped Bessel
• GPS L1
• GPS L2
• GPS User
• Linear with angle
• Omni directional
• Parabolic rolloff
• Sine(x)/x

These are specified in the sections below.

Bessel

This is the theoretical model for antenna performance, and is given below.

If:

$$D/\lambda =\frac{1.61374}{\pi \times \sin \left(\frac{{\phi }_0}{2}\right)}$$

Then:

$$G_{REL}=20{\log }_{10}\left(\frac{2\times |j1(\pi (D/\lambda )\phi )|}{\pi D/\lambda |\sin \phi |}\right)$$

Capped Bessel

The capped Bessel follows the Bessel for the main beam, and then for the side-lobes it connects the peaks.

GPS L1

The following pattern is used:

$$\begin{array}{ll}{G}_{abs}=11.77+\frac{3.4}{1+\exp \left[-\left(\frac{\theta -4.944}{1.537}\right)\right]}& \text{ if }0\le \theta \le 11\\ G_{abs}=-33.61+\frac{49.03}{1+\exp \left[-\left(\frac{\theta -21.83}{-2.440}\right)\right]}& \text{ if }11<\theta \le 22\\ G_{abs}=-10.86+\frac{10.02}{1+\exp \left[-\left(\frac{\theta -24.13}{1.194}\right)\right]}& \text{ if }22<\theta \le 29\\ G_{abs}=-7.749+\frac{6.753}{1+\exp \left[-\left(\frac{\theta -40.32}{-3.216}\right)\right]}& \text{ if }29<\theta \le 45\\ G_{abs}=-7.319+\frac{4.783}{1+\exp \left[-\left(\frac{\theta -46.49}{1.122}\right)\right]}& \text{ if }45<\theta \le 52\end{array}$$

$$\begin{array}{ll}{G}_{abs}=-27.12+\frac{27.05}{1+\exp \left[-\left(\frac{\theta -73.79}{-10.12}\right)\right]}& \text{ if }52<\theta \le 82\\ G_{abs}=37.65-1.266\theta +0.0111\theta -3.19e^{-5}{\theta }^3& \text{ if }82<\theta \le 174\\ G_{abs}=323.1-2.05\theta & \text{ if }174<\theta \le 176\\ G_{abs}=-38.27+\frac{6.199}{1+\exp \left[-\left(\frac{\theta -177.4}{0.6702}\right)\right]}& \text{ otherwise }\end{array}$$

Then:

$$G_{rel}=G_{abs}-11.90104866$$

Note this assumes that the peak gain is set to $11.90104866\mathrm{dB}$.

GPS L2

The following pattern is used:

$$\begin{array}{ll}{G}_{abs}=-67.31+\frac{80.51}{1+\exp \left[-\left(\frac{\theta -33.91}{-4.677}\right)\right]}& \text{ if }0\le \theta \le 30\\ G_{abs}=-19.79+\frac{17.58}{1+\exp \left[-\left(\frac{\theta -30.416}{4.51}\right)\right]}& \text{ if }30<\theta \le 47\\ G_{abs}=-27.62+\frac{28.58}{1+\exp \left[-\left(\frac{\theta -88.75}{-21.57}\right)\right]}& \text{ if }47<\theta \le 97\\ G_{abs}=-97.44-2.081\theta +-0.0167\theta -4.05e^{-5}{\theta }^3& \text{ if }97<\theta \le 174\\ G_{abs}=-30.23+\frac{9.609}{1+\exp \left[-\left(\frac{\theta -176.1}{0.9522}\right)\right]}& \text{ otherwise }\end{array}$$

Then:

$$G_{rel}=G_{abs}-13.13461172$$

Note this assumes that the peak gain is set to $13.13461172\mathrm{dB}$.

GPS User

The following pattern is used from ITU-R document 8D/142 from $13^{\text{th }}$ October 1998:

$$G_{abs}=7-1.957e^{-3}{\theta }^{2.01}\text{ if }\theta \le 80$$

$$G_{abs}=21.59-0.3882\theta +5.455e^{-4}{\theta }^2\text{ otherwise }$$

Then:

$$G_{rel}=G_{abs}-7$$

Note this assumes that the peak gain is set to $7\mathrm{dB}$.

Linear

This algorithm is used so that the offaxis angle can be determined from the offaxis gain. The equation is:

$${\mathrm{G}}_{\mathrm{rel}}=-\theta$$

Omni Directional

This gives the same value in all directions and is hence essentially isotropic. The peak gain is set by default to 0 dB, but can be any user entered value.

Parabolic

This pattern is parabolic with floor defined. The equation is:

$$G_{\text{rel }}=\max \left[G_{\text{floor }},-12{\left(\frac{\theta }{{\theta }_{3\mathrm{dB}}}\right)}^2\right]$$

The ${\mathrm{G}}_{\text{floor }}$ is input by the user. A typical value is $-30\mathrm{dB}$.

Sin(x)/x

The calculation is the same as the Bessel Function, but replacing the call to Bessel by sin.

Archived Gain Patterns

The following gain patterns are included in Visualyse Interplanetary for reasons of backward compatibility:

• Appendix 29 Earth Station
• Analytic ES
• Analytic NGSO
• Cosine
• FSATMULTI_1A Earth Station
• FSATMULTI_1A Type A
• NGSO FSS RX
• NGSO FSS TX
• SMATV
• Sine
• SkyBridge RX Type A
• SkyBridge TX Type A
• TVRO
• Teledesic 2 - RX
• Teledesic 2 - RX fixed BW
• Teledesic 2 - TX
• Teledesic 2 - TX fixed BW
• Teledesic Type A
• Teledesic Type B
• Teledesic Type C

More information is available on request.

Propagation models

Visualyse Interplanetary contains a number of propagation models that can be activated either individually or in combination. These are described in the sections below.

• ITU-R Recommendations
• Other Standard Models
• Terrestrial Mobile
• Fixed loss Models
• Extra Clutter Models
• Other Models
• Use with Define Variable Module

ITU-R Recommendations

• Recommendation ITU-R P.452
• Recommendation ITU-R P.525
• Recommendation ITU-R P.526
• Recommendation ITU-R P.528
• Recommendation ITU-R P.530
• Recommendation ITU-R P.530 Multipath
• Recommendation ITU-R P.530 Rain Fade
• Recommendation ITU-R P.618
• Recommendation ITU-R P.676
• Recommendation ITU-R P.840
• Recommendation ITU-R SF.1395
• Recommendation ITU-R P.1546
• Recommendation ITU-R P.1791
• Recommendation ITU-R P.1812
• Recommendation ITU-R P.2001

Recommendation ITU-R P.452

Prediction procedure for the evaluation of microwave interference between stations on the surface of the Earth at frequencies above about 0.7 GHz

This option uses the model in Recommendation ITU-R P.452 for line of sight and trans-horizon loss valid for frequencies between 100 MHz and 50 GHz, though recent research suggests it might also be applicable at higher frequencies. Visualyse Interplanetary includes all the key components of the model, including free space path loss, multi-path enhancements, gaseous absorption, diffraction, ducting and layer reflection/refraction, troposcatter and clutter loss.

Data needed for the model can be derived directly from the IDWM database if you are using the IDWM module, otherwise they must be input by hand. If a terrain database is available it will be used to derive parameters relating to the path including diffraction. The clutter model can use the land usage database or parameters entered by hand.

The associated percentage of time can either be user-entered or selected at random for Monte Carlo style analysis. The range in the Recommendation is 0.001 % to 50%, reflecting the fact that this model is designed for interference paths and so does not include effects for over 50% of time such as deep fades.

Recommendation ITU-R P.525

Calculation of free-space attenuation

This is the basic free space path loss that can be used for all paths at all frequencies. Note that by default for all paths including terrestrial no consideration is made as to whether there is line of sight, and losses increase steadily by distance.

Recommendation ITU-R P.526

Propagation by diffraction

Recommendation ITU-R P.526 defines models to be used in calculating diffraction losses for trans-horizon links for frequencies above about 30 MHz. Visualyse Interplanetary implements both the smooth Earth model and the modified three-knife edge Deygout construction when terrain data is available.

Recommendation ITU-R P.528

Propagation curves for aeronautical mobile and radionavigation services using the VHF, UHF and SHF bands

This Recommendation is designed to predict propagation loss for air to ground / ground to air links. It gives curves of loss vs. distance for frequencies 125, 300, 1200, 5100, 9400 and 15 500 MHz and at TX/RX heights of 15m, 1 km, 10 km, and 20 km for probabilities of 5%, 50% and 95% of time. Interpolation is used to derive the loss for other frequencies, heights and percentages of time.

Recommendation ITU-R P.530

Propagation data and prediction methods required for the design of terrestrial line-of-sight systems

Visualyse Interplanetary contains two of the propagation models in Recommendation ITU-R P.530 - rain and multipath fading, as describing below.

Parameters in various equations within the Recommendation have been derived from fading data from links operating in the range 450 MHz – 37 GHz, though they should be valid up to frequencies of 50 GHz.

Recommendation ITU-R P.530 Multipath

This option uses the fade distribution defined in Method 1 of Recommendation ITU-R P.530 to generate a fade or multipath enhancement either for a specific percentage of time or at random using a Monte-Carlo technique.

This method is applicable to lineofsight fixed links and is intended for initial planning and link design. The geoclimatic factor K parameter is derived from the Recommendation.

Recommendation ITU-R P.530 Rain Fade

This option uses the model defined in Recommendation ITU-R P.530 to generate a rain fade loss. It is intended to be used for line-of-sight fixed links.

The rain rate can either be entered directly or read automatically from Recommendation ITU-R P.837. The associated percentage of time can be either entered directly or generated at random for Monte Carlo analysis.

Recommendation ITU-R P.618

Propagation data and prediction methods required for the design of Earthspace telecommunication systems

This Recommendation models rain attenuation on earth to space / space to earth links and the rain rate can come from ITU-R Recommendation P.837 versions or directly entered by the user. It is valid for frequencies up to 55 GHz.

The associated percentage of time can be either entered directly or generated at random for Monte Carlo analysis.

Recommendation ITU-R P.676

Attenuation by atmospheric gases

This method implements losses due to dry air and water vapour defined in Annex 2 of Recommendation ITU-R P.676, and is intended to be used for earth to space / space to earth links. It is valid for frequencies from 1 GHz to 350 GHz.

The values of the temperature, water vapour density and pressure can be entered directly.

Recommendation ITU-R P.840

Attenuation due to clouds and fog

This method implements losses due to attenuation from cloud and fogs as described in Recommendation ITU-R P.840, and is intended for earth to space / space to earth links above about 10 GHz.

The values of the water concentration in the cloud and associated percentage of time can be entered directly.

Recommendation ITU-R SF.1395

Minimum propagation attenuation due to atmospheric gases for use in frequency sharing studies between the fixed-satellite service and the fixed service

This model calculates the attenuation due to atmospheric gases in more detail for low elevation paths than the direct method in Recommendation ITU-R P. 676. It fits a set of curves to a numerical integration at key frequencies.

Recommendation ITU-R P.1546

Method for point-to-area predictions for terrestrial services in the frequency range 30 MHz to 3 000 MHz

This propagation model is designed for use in modelling terrestrial services; in particular point-to-area predictions in the frequency range 30 MHz to 3 GHz.

Propagation parameters required by this model such as distance over water and whether warm water can be automatically extracted from IDWM or entered by hand.

The clutter model can use the land usage database or parameters entered by hand.

Note that this model calculates loss assuming high height transmitter and low height receiver and it is assumed that the loss in the return direction is then the same. The loss is calculated to a receiver height of 10m and then adjustments must be made for the actual receiver height.

Recommendation ITU-R P.1791

Propagation prediction methods for assessment of the impact of ultra-wideband devices

This model is a generic propagation model for short range scenarios built up work within the ITU-R studying ultra-wideband (UWB) devices. In the Recommendation it is basically a dual slope model with log-normal distribution: however we have included a number of extensions that were discussed during its development to make it a more generic short range propagation model.

In its more flexible generic form it comprises four elements:

1. Basic loss: this can either be a single slope or dual slope, with a specified break distance and either one or two slopes. For wide band signals such as UWB it should use the adjusted basic path loss that takes account of the frequency range
2. Optional indoor-outdoor propagation loss: it is assumed that the loss varies depending upon the building type and distance to exterior wall, with distribution defined by two break points and assuming loss is capped below and above and with linear interpolation between break points
3. Optional additional log-normal loss with mean zero and standard deviation a user entered parameter, which can be different before and after the break point
4. Optional additional loss, to cover other propagation effects

The log-normal loss can include enhancements, which could in theory result in less loss than would be the case with free space path loss. The loss can therefore be capped at this value to ensure physically plausible results.

Recommendation ITU-R P.1812

A path-specific propagation prediction method for point-to-area terrestrial services in the VHF and UHF bands

This propagation model is designed for use in modelling terrestrial services; in particular point-to-area predictions in the frequency range 30 MHz to 3 GHz.

Conceptually it is a mixture of Recommendations ITU-R P.452 and ITU-R P.1546 using:

• The path profile extraction and analysis method in ITU-R P.452 to work out propagation loss taking into account details of the terrain
• The clutter loss and percentage of locations within a pixel methodology within ITU-R P.1546.

The propagation model in ITU-R P.452 can calculate propagation loss for percentages of time down to 0.001% for frequency over about 700 MHz. However it is not feasible at present to predict propagation losses for very small percentages of time for the lower frequencies ranges covered by ITU-R P.1812: hence it is restricted to percentages between 1 and 50%.

Visualyse Interplanetary includes all the key components of the model, including gaseous absorption, fading, ducting, troposcatter and clutter. Data needed for the troposcatter model can be derived directly from the IDWM database if you are using the IDWM module, otherwise they must be input by hand. If a terrain database is available it will be used to derive parameters relating to the path including diffraction. If a land use database is available it will be used to adjust the path profile with the heights indicated for each clutter category.

Propagation parameters required by this model such as distance over water and whether warm water can be automatically extracted from IDWM or entered by hand.

Recommendation ITU-R P.2001

A general purpose wide-range terrestrial propagation model in the frequency range 30 MHz to 50 GHz

This propagation model is designed for terrestrial sharing scenarios, in particular for use in Monte Carlo style methodologies.

Many of the other propagation models handle fading and enhancements separately. For example in sharing scenarios involving the fixed service there are two models:

• Wanted path: as well as free space path loss, Rec. P.530 is used to model fades on the link below the 50% of time level
• Interference path: Rec. P.452 is used to model interference including enhancements above the 50% of time level

When undertaking Monte Carlo modelling it is important to model the full range of probabilities for wanted and interfering paths so that the convolution of C/(N+I) is correctly calculated. This is was Rec. P.2001 is designed to do.

This Recommendation has similarities with both P.452 and P.1812 in its handling of terrain paths but extends both to cover the full range of percentage of times [0.00001% to 99.99999%].

At present no clutter model is included in this Recommendation but if need be the Extra models terminal clutter loss can be added to the list of propagation models with P.2001.

Other Standard Models

• Crane Rain Model
• Appendix S.7 (WRC-95)
• TIA Bulletin 10F
• Longley-Rice

Crane Rain Model

This implements the Crane rain model with options to include the NASA data set. It is intended to be used for earth to space / space to earth paths.

Either the climatic region or rain rate and rain height can be entered.

The associated percentage of time can be either entered directly or generated at random for Monte Carlo analysis.

Note: The implementation is based on Section 4.3 of Electromagnetic Wave Propagation Through Rain by Robert K. Crane (© 1996 John Wiley & Sons, Inc. ISBN 0-471-61376).

The following modifications were made when implementing the model:

• The section of Crane that deals with horizontal paths over $22.5\mathrm{km}$ is only used when a climate region is specified.
• In equation 4.8, $A_F(R,D)=\gamma (R)\frac{e^{y\delta (R)}-1}{y}$ the $\delta (R)$ is replaced with $D$

$$\begin{array}{rl}& A_T(R,D)=\gamma (R)\\ & =\gamma (R)\frac{e^{yD}-1}{y}\end{array}$$

• This is similar to the method used in the NASA Propagation Effects Handbook for Satellite Systems Design (1989, fourth edition, section 6.3.2.1, page 6-23).
• Equation 4.10 is used instead of the approximations which follow it.
• Equation 4.13 is used instead of 4.12
• Alpha and $\mathrm{K}$ in section 4.3.1 are calculated using Rec. ITU-R P.838 $(1992)$

Appendix S.7 (WRC-95)

Visualyse Interplanetary includes the propagation model defined in Appendix S.7 as agreed at WRC 95 (previously known as Appendix 28). This can be either Mode 1, Mode 2 or a combined model. It is valid between 1 and 40 GHz.

If the IDWM model is available then it will extract the zone(s) required for Mode 1 calculations automatically, otherwise a single zone can be directly selected. The associated percentage of time can be either entered directly or generated at random for Monte Carlo analysis.

If the IDWM model is available then it will extract the rain rate, rain cell size, and vapour density required for Mode 2 calculations automatically, otherwise these fields can be entered directly.

TIA Bulletin 10F

The US Telecommunications Industry Association has produced a technical bulletin relating to interference calculations for fixed service systems. One element is a model for short term deep fading. Visualyse Interplanetary allows this model to be used across all percentages of time by linearly extrapolating from deep to shallow fading.

Longley-Rice

The Longley-Rice Irregular Terrain Model

This propagation model is the point to point version of the National Telecommunications and Information Administration (NTIA) Institute for Telecommunication Sciences’s Irregular Terrain Model (ITM) version 1.2.2.

As well as using the path profile extracted from the terrain database there are also options to select the surface refractivity, dielectric ground constant, ground conductivity and radio climate from standard options.

The median propagation loss can be adjusted in two dimensions:

• Time: you can enter the percentage of time that the propagation loss $A$ will not be exceeded i.e. $A\left(q_T\right)$
• Confidence: Confidence that the propagation loss will $A\left(q_T\right)$ not exceed the level for the specified $q_{\text{T }}$ of time

Terrestrial Mobile

Visualyse Interplanetary contains several standard propagation models to calculate median loss for terrestrial mobile applications.

• Egli
• Hata / COST-231
• Lee
• IMT Path Loss Models
• Recommendation ITU-R P.2109: Building Entry Loss
• Recommendation ITU-R P.2108

Egli

The Egli model is an empirical model applicable to a mobile environment. It is a $1/r^4$ model with corrections for antenna heights and frequency.

The calculations for this model have been derived from algorithms in: “The Mobile Radio Propagation Channel”, J. D. Parsons, Pentech Press 1992. This simplified Egli model is valid for use at frequencies between 90 MHz and 1 GHz and has no input parameters.

Hata / COST-231

The Hata model is an empirical model applicable to a mobile environment, which gives the median loss and is widely used and was extended by COST-231. The original Hata model was valid for frequencies from 150 MHz – 1,500 MHz and the COST-231 version was extended to 2 GHz.

The implementation of COST-231 is consistent with the approach in defined in ECC Report 68.

It should be noted that the Hata version of this model is asymmetric – the loss is assumed to be calculated in the direction from the (higher) base station to the (lower height) mobile station. To allow calculation in the reverse direction, the COST-231 implementation assumes the station with the highest antenna is the base station independent of other parameters of the network.

In both cases the environment can be selected as one of urban, suburban or rural.

Lee

The Lee model is an empirical model applicable to a mobile environment, and allows the median transmission loss, the slope of path loss curve, and frequency adjustment factors to be entered.

The calculations for this model have been derived from algorithms in: “The Mobile Radio Propagation Channel”, J. D. Parsons, Pentech Press 1992.

IMT Path Loss Models

These models are designed for short range paths for the wanted or interfering signals of IMT-2020 / 5G systems. The models included are:

• ABG
• CI/CIF
• 3GPP TR 38.900
• 3GPP TR 38.901
• WINNER II
• WINNER+
• ITU-R Report M.2135

The alpha, beta, gamma (ABG) and close-in / close-in with frequency-dependent path loss exponent (CI/CIF) path loss models were defined in document ITU-R WP 5D/TEMP/292. Each requires a set of parameters which will depend upon the environment models, such as the examples in the document referenced.

The 3GPP wanted signal path loss models are defined in these documents:

• 3GPP Technical Report (TR) 38.900: Study on channel model for frequency spectrum above 6 GHz
• 3GPP TR 38.901: Study on channel model for frequencies from 0.5 to 100 GHz

These define path loss models for specific environments, taking into account whether the path is line of sight (LOS) or non-LOS. For some environments the path could also be from indoor to outdoor.

The 3GPP TR 38.900 and 38.901 path loss models are not symmetric, in that they have as inputs the BS and UE heights. To ensure that Visualyse Interplanetary identifies the stations correctly, it should be configured so that:

• The BS is a Terrestrial Fixed Station
• The UE is a Mobile Station

Note that 3GPP TR 38.900 and 38.901 have, for some environments, assumptions about the BS height. For example in the UMa environment it is assumed that the height of the BS is 25m while for UMi – Street Canyons this is 10m. This value would be used within these path loss models irrespective of the height set in the station dialog. The equations to determine the probability of LOS makes similar assumptions about antenna heights.

In addition, some parameters have ranges of acceptable values which are enforced. For example, the RMa environment requires the average street width and building height to be entered which are constrained to be between 5m and 50m.

The WINNER propagation models are described in the following documents:

• WINNER II Channel Models (Project IST-4-027756, versions D1.1.2 V1.2)
• WINNER+ Final Channel Models (Project CELTIC / CP5-026, version 1.0)

Recommendation ITU-R P.2109: Building Entry Loss

Recommendation ITU-R P.2109 (previously described as P.BEL) defines the entry / exit loss for a path between a station inside and another station outside a building, as in the figure below:

The loss will depend upon a number of factors, such as frequency, elevation angle of path at the station inside and the type of building. Measurements noted that a key factor was whether the exterior is made from:

• Traditional materials

• Thermally efficient materials

There can be a wide variation in losses depending upon details of the materials, the location of the station inside, the floors, furniture etc. Therefore, rather than giving a single value a statistical model was used that defines the building entry loss exceeded for a given likelihood.

The inputs are therefore:

• Frequency
• Elevation angle
• Building material
• Probability

The probability can either be entered or selected at random for Monte Carlo analysis. The elevation angle can either be entered or will be calculated from the radio path.

Recommendation ITU-R P.2108

Recommendation ITU-R P.2108 (previously described as P.Clutter) contains three component models depending upon whether:

• Terminal below representative clutter height
• Terrestrial terminal within the clutter
• One terminal is within the clutter and the other is a satellite, aeroplane or other platform above the surface of the Earth.