Upgrade of SBAS Simulator User Manual - · PDF fileLANOPWE Longitude of Ascending Node of...

Iguassu Software Systems

Ref : SBAS-SIM-MANUAL

Issue : 1 Rev. : 3 Date : 02/11/2015 Page : 1

Name & Function Signature Date

Prepared by: Jiri Doubek, Igor Kokorev 04/05/2015

Checked by:

Authorised by:

Approved by: Jiri Doubek, Project Manager 02/11/2015

Upgrade of SBAS Simulator

User Manual




DOCUMENT INFORMATION

Contract data

Contract Number 4000111120/14/NL/CBi

Contract Issuer ESA - ESTEC

Distribution List

Iguassu Software

Systems

Jiri Doubek

Miroslav Houdek

Daniel Chung

Igor Kokorev

ESA

Jaron Samson

Constantin Alexandru Pandele

Katarzyna Urbanska

Christelle Iliopoulos

Document Change Record

Iss./Rev. Date Section/Page Change Description

1.0 04/05/2015 all Document proposal

1.1 02/07/2015 2.3.2.1 Command line simulations

1.2 19/08/2015

4.1.2.1,

4.5.4.1,

4.5.4.2, 5.10

GEO satellites longitude, ionospheric

settings, DOC simulations

1.3 02/11/2015

3.5, 5.3.4, 5.6,

5.8.2, 5.8.3,

5.11.2, 6.1.1

Region graphs: changes in colour scale

and in area layers.




1 Introduction The present document is the User Manual applicable to “Upgrade of SBAS Simulator” project.

The objective of this activity was to update the SBAS Simulator, a tool developed under the

ESA PECS programme in 2009, which provides an environment where users can perform

various simulations of Satellite Based Augmentation Systems (SBAS). The upgrade of the

SBAS Simulator supports both, the analysis of the performance of the current EGNOS system,

as well as the future evolution of EGNOS.

1.1 Document Structure

This document is organised as follows:

Section 1 provides an introduction, the table of contents and a list of documents and acronyms

Section 2 describes the operations environment

Section 3 gives a short start-up guide

Section 4 details all SBAS Simulator settings

Section 5 describes all analyses and tools

Section 6 provides information to region graphs

Section 7 gives an overview of SBAS Simulator files

1.2 Document Status

This is a definitive issue of this document.




1.3 Table of Contents

1 Introduction ........................................................................................................................ 3

1.1 Document Structure .................................................................................................... 3

1.2 Document Status ......................................................................................................... 3

1.3 Table of Contents ......................................................................................................... 4

1.4 Applicable Documents ................................................................................................. 7

1.5 Reference Documents ................................................................................................. 7

1.6 Terms, definitions and abbreviated terms .................................................................. 7

1.7 Purpose of the Software ............................................................................................ 10

1.8 External view of the software .................................................................................... 10

2 Operations environment .................................................................................................. 10

2.1 General ...................................................................................................................... 10

2.2 Hardware configuration ............................................................................................ 12

2.3 Software configuration .............................................................................................. 12

2.3.1 Applet configuration .......................................................................................... 12

2.3.2 Standalone application configuration ................................................................ 12

2.4 Operation constraints ................................................................................................ 14

3 Getting Started ................................................................................................................. 14

3.1 Introduction ............................................................................................................... 14

3.2 Sample DOP analysis .................................................................................................. 15

3.2.1 Running the simulator ........................................................................................ 15

3.3 Constellations and satellites ...................................................................................... 16

3.4 Simulation time and area .......................................................................................... 16

3.5 DOP options and analysis .......................................................................................... 16

4 Settings ............................................................................................................................. 17

4.1 Space segment settings ............................................................................................. 18

4.1.1 Satellite settings ................................................................................................. 18

4.1.2 Adding and removing satellite from a constellation .......................................... 26

4.1.3 Adding and removing a constellation ................................................................ 27

4.1.4 Setting the constellation to the default state .................................................... 30




4.1.5 Constellation source ........................................................................................... 31

4.1.6 Constellation settings ......................................................................................... 35

4.1.7 Frequency mode and frequency values ............................................................. 37

4.2 User segment settings ............................................................................................... 38

4.2.1 Geographical area settings ................................................................................. 38

4.2.2 User mask settings ............................................................................................. 39

4.2.3 Service settings ................................................................................................... 39

4.3 Ground segment settings .......................................................................................... 39

4.3.1 RIMS selection .................................................................................................... 40

4.3.2 RIMS configuration ............................................................................................. 41

4.3.3 RIMS network configuration .............................................................................. 44

4.3.4 RIMS error distribution ...................................................................................... 44

4.4 Time settings .............................................................................................................. 45

4.5 Macro-model settings ................................................................................................ 46

4.5.1 Constellation sigma values ................................................................................. 47

4.5.2 UDRE model ........................................................................................................ 49

4.5.3 DFRE model ........................................................................................................ 50

4.5.4 Ionospheric model .............................................................................................. 51

4.5.5 SBAS settings ...................................................................................................... 55

4.5.6 XPL dynamic conditions ...................................................................................... 56

4.5.7 Navigation solution unknowns ........................................................................... 58

4.6 Working directory and scenario folder...................................................................... 59

4.7 Scenario ..................................................................................................................... 59

5 Analyses and Tools ........................................................................................................... 60

5.1 General computations ............................................................................................... 61

5.2 Computations of satellite variance (σ) ...................................................................... 62

5.3 DOP ............................................................................................................................ 63

5.3.1 Availability for a point ........................................................................................ 63

5.3.2 Statistics for a point ............................................................................................ 64

5.3.3 Availability for a region ...................................................................................... 65




5.3.4 Statistics for a region .......................................................................................... 65

5.4 NSE ............................................................................................................................. 65

5.5 XPL ............................................................................................................................. 66

5.6 Availability ................................................................................................................. 67

5.7 Continuity .................................................................................................................. 69

5.8 IONO .......................................................................................................................... 70

5.8.1 IPP location ......................................................................................................... 71

5.8.2 IGP statistics ....................................................................................................... 71

5.8.3 Sigma GIVE calculation ....................................................................................... 72

5.9 Monitoring ................................................................................................................. 73

5.10 DOC simulations ........................................................................................................ 74

5.10.1 XDOC ................................................................................................................... 75

5.10.2 IDOC .................................................................................................................... 76

5.10.3 ADOC .................................................................................................................. 76

5.11 Coverage, elevation, ground tracks ........................................................................... 77

5.11.1 Coverage ............................................................................................................. 77

5.11.2 Elevation ............................................................................................................. 78

5.11.3 Ground tracks ..................................................................................................... 79

5.12 Delta map .................................................................................................................. 80

5.13 3D view ...................................................................................................................... 81

5.14 Sky plot ...................................................................................................................... 82

6 Graphs .............................................................................................................................. 82

6.1 Region graph .............................................................................................................. 83

6.1.1 Region graph controls ........................................................................................ 83

7 SBAS Simulator Files ......................................................................................................... 84

7.1 Simulation steps ........................................................................................................ 84

7.2 Data and meta-files ................................................................................................... 84




1.4 Applicable Documents

Reference Title

[AD1] Statement of Work, Ref. ESA-DTEN-NF-SoW/03982, Issue 1, Revision 0, 26/03/2013

1.5 Reference Documents

Reference Title

[RD1] SBAS Simulator User Manual, www.iguassu.cz/sbas-sim/sbas_sim_manual.pdf

[RD2] SBAS Simulator Upgrade, TN 1- RIMS error over bound; Ref.: SBAS-SIM-TN-01-0.3; Issue: 0; Revision: 3; Date: August 18, 2014

[RD3] Minimum Operational Performance Standards (MOPS) for airborne navigation equipment (2D and 3D) using the Global Positioning System (GPS) augmented by the Wide Area Augmentation System (WAAS)

[RD4] Ionospheric Macro Model for SBAS Service Volume Simulations; S. Schlueter; Issue: 1, Revision: 1; Date: February 9, 2015

[RD5] IS-GPS-200F; Revision: F; September 21, 2011

[RD6] Computation method for SBAS continuity; F. Salabert; NSP March 2013 WGW/flimsy8

1.6 Terms, definitions and abbreviated terms

Acronym Details

AD Applicable Documents

ADOC Advanced Depth Of Coverage

agl Almanac GLONASS

APV Approach Procedure with Vertical Guidance

CSV Comma Separated Values

CRC Cyclic Redundancy Check

df Dual Frequency

DFRE Dual Frequency Range Error

DOC Depth Of Coverage




Acronym Details

DOP Dilution Of Precision

ECAC European Civil Aviation Conference

ECEF Earth-Centered, Earth-Fixed

EGNOS European Geostationary Navigation Overlay Service

EMS EGNOS Message Server

ENP European Neighbourhood Policy

ENU East North Up

ESA European Space Agency

EPO EGNOS Project Office

flt Fast and Long Term correction

GDOP Geometric Dilution Of Precision

GEO Geostationary (satellite/constellation)

GIVE Grid Ionospheric Vertical Error

GPS Global Positioning System

HAL Horizontal Alert Limit

HDOP Horizontal Dilution Of Precision

HNSE Horizontal Navigation System Error

HPL Horizontal Protection Level

IDOC Inverse Depth Of Coverage

IGP Ionospheric Grid Point

IONEX IONosphere map EXchange format

IOV In-Orbit Validation

ISS Iguassu Software Systems

IPP Ionospheric Pierce Point

JRE Java Runtime Environment

LANOPWE Longitude of Ascending Node of Orbit Plane at Weekly Epoch

LPV Localiser Performance with Vertical Guidance

LTC Long-Term Corrections

MEO Medium Earth Orbit (satellite)

MOPS Minimum Operational Performance Standards

MT Message Type




Acronym Details

NPA Non-Precision Approach

NSE Navigation System Error

OS Operating System

PA Precision Approach

PC Personal Computer

PDOP Positional Dilution Of Precision

QZSS Quasi-Zenith Satellite System

RAAN Right Ascension of the Ascending Node

RD Reference Document

RIMS Ranging and Integrity Monitoring Station(s)

RINEX Receiver Independent Exchange Format

SBAS Satellite Based Augmentation System

sf Single Frequency

SOW Seconds of Week

TDOP Time Dilution Of Precision

TLE Two Line Elements

TN Technical Note

toa Time of Applicability

UDRE User Differential Range Error

UIRE User Ionospheric Range Error

UIVE User Ionospheric Vertical Error

UTC Universal Coordinated Time

VAL Vertical Alert Limit

VDOP Vertical Dilution Of Precision

VNSE Vertical Navigation System Error

VPL Vertical Protection Level

XAL Alert Limits

XDOC Depth Of Coverage

XPL Protection Levels




1.7 Purpose of the Software

The principle use of the Upgrade of SBAS Simulator is to simulate the environment of SBAS

systems. The user can configure in detail the space, ground and user segment. The software

is capable to perform simulation in single and dual frequency mode and visualise results in

exportable graphs. The main benefit is to show the future potentials of SBAS systems and

multi constellation solutions.

1.8 External view of the software

The software can run without any external files. Anyway it supports loading configuration

files that store all possible settings of the tool. No restrictions apply to configuration files.

2 Operations environment

2.1 General

SBAS Simulator is written in Java and requires the JRE to be installed. It is a multi-platform

application and can be run in any OS supporting Java. The tool can be started as a

standalone application or as an applet from the web browser. Applet version requires

configuration of the Java security. The site running the applet shall be included in the Java

Exception Site List (Figure 1). User can also switch the Java Security Level to medium, but it is

not recommendable. Running the tool in the browser also requires accepting the Java

Security Warning (Figure 2).




Figure 1: Java Exception Site List. In this example the software runs under the www.iguassu.cz which has been added to the list.

Figure 2: Java Security Warning. User shall accept the risk to be able to run the SBAS Simulator in the browser.




2.2 Hardware configuration

SBAS Simulator runs in an ordinary PC and does not require any non-standard hardware.

Long simulations are recommended to run on more powerful machine with several CPU

cores.

2.3 Software configuration

The SBAS Simulator can be run as a standalone Java application or as an applet.

Configurations for both runs are described in the following subsections.

2.3.1 Applet configuration

The software needs JRE and properly configured Java security as explained in 2.1.

2.3.2 Standalone application configuration

When the user runs the standalone application for the first time, the command line may

print a warning. In that case the tool shall be run with administrative privileges to create

required registry record. Following runs can be executed with normal privileges.

2.3.2.1 Command line options

When running the standalone application, user can provide several arguments.

It is possible to define what is to be shown in the main panel on launch. When user clicks the

Settings button in the scenario panel (see section 4.7) or any button in the Analyses or Tools

panel (see section 5), the main panel is updated. By supplying a TAB argument to the

standalone application, the simulator opens the desired content in the main panel. At most

one TAB argument shall be supplied. If no TAB argument is supplied, the description panel is

loaded into the main panel. Table 1 contains all the possible TAB arguments, including

examples of usage.

TAB argument

Button equivalent

Panel containing the button

Example usage (given the filename of the .jar file is SBAS_Simulator_2.jar)

SE Settings Scenario panel java –jar SBAS_Simulator_2.jar SE

DE Description Analysis panel java –jar SBAS_Simulator_2.jar DE

DO DOP Analysis panel java –jar SBAS_Simulator_2.jar DO

NS NSE Analysis panel java –jar SBAS_Simulator_2.jar NS

XP XPL Analysis panel java –jar SBAS_Simulator_2.jar XP

AV AVAILABILITY Analysis panel java –jar SBAS_Simulator_2.jar AV

CO CONTINUITY Analysis panel java –jar SBAS_Simulator_2.jar CO

IO IONO Analysis panel java –jar SBAS_Simulator_2.jar IO

MO MONITORING Analysis panel java –jar SBAS_Simulator_2.jar MO

XD XDOC Analysis panel java –jar SBAS_Simulator_2.jar XD

ID IDOC Analysis panel java –jar SBAS_Simulator_2.jar ID

AD ADOC Analysis panel java –jar SBAS_Simulator_2.jar AD

CV COVERAGE Analysis panel java –jar SBAS_Simulator_2.jar CV




GN GND TRACKS Analysis panel java –jar SBAS_Simulator_2.jar GN

DL DELTA MAP Tools panel java –jar SBAS_Simulator_2.jar DL

VS View Situation Tools panel java –jar SBAS_Simulator_2.jar VS Table 1: Possible TAB arguments.

It is also possible to define files with constellations, RIMS and other settings to load an

already existing scenario. This is similar to the way constellations, RIMS or other settings are

loaded into the simulator using the Load button of the scenario panel (see 4.7). It is possible

to supply 3 file type arguments at most (/CF, /RF and /OF, all once) and at most one of each

kind. Each of these arguments is followed by a colon and the path to the file.

Another way how to specify configuration files is to put them in the scenario directory and

specify the relative path to the scenario directory using the argument /SCEN. In that case

configuration files shall have names constells.sce, rims.sce and other.sce. Table 2 contains all

arguments related to loading existing scenarios from files. This table also contains example

usages of these arguments.

File type argument

File type Example usage (given the filename of the .jar file is

SBAS_Simulator_2.jar)

/CF File with constellations java –jar SBAS_Simulator_2.jar /CF:constellations.sce

/RF File with RIMS java –jar SBAS_Simulator_2.jar /RF:rims_file.sce

/OF File with other settings java –jar SBAS_Simulator_2.jar /OF:other_data.sce

/SCEN Relative constellation directory from the application path.

java –jar SBAS_Simulator_2.jar /SCEN:relative_dir

Table 2: Possible file type arguments.

SBAS Simulator also allows running the simulation through the command line without

opening the graphical interface. Each simulation corresponds to an argument as shown in

Table 3. Commands can be combined with arguments /CF, /RF, /OF or /SCEN.

Simulation argument

Simulation Example usage (given the filename of the .jar file is

SBAS_Simulator_2.jar)

dop DOP java –jar SBAS_Simulator_2.jar dop

nse NSE java –jar SBAS_Simulator_2.jar nse

mon Monitoring java –jar SBAS_Simulator_2.jar mon

xpl XPL java –jar SBAS_Simulator_2.jar xpl

avail Availability java –jar SBAS_Simulator_2.jar avail

cont Continuity java –jar SBAS_Simulator_2.jar cont

iono Ionosphere java –jar SBAS_Simulator_2.jar iono

xdoc XDOC java –jar SBAS_Simulator_2.jar xdoc

idoc IDOC java –jar SBAS_Simulator_2.jar idoc

adoc ADOC java –jar SBAS_Simulator_2.jar adoc

gtr Ground tracks java –jar SBAS_Simulator_2.jar gtr




cov Coverage java –jar SBAS_Simulator_2.jar cov

ele Elevation java –jar SBAS_Simulator_2.jar ele Table 3: Arguments for command line simulations.

To see all the available arguments that can be put to the standalone application, the /?

argument is used. If this argument is supplied, no other argument can be provided at the

same time. If the filename of the .jar file is SBAS_Simulator_2.jar, this shall be written in the

command line:

This will also show some examples how to use the possible arguments.

2.4 Operation constraints

SBAS Simulator has just a standard mode of operation. It requires the internet access for

ephemeris updates. The tool shall have also writing and reading privileges for the current

scenario folder. The software can run without internet access, but the absence of writing

and reading privileges makes the simulator unusable.

3 Getting Started This section introduces the SBAS Simulator and its basic functions. It also guides user

through a sample DOP simulation step by step.

3.1 Introduction

The Upgrade of SBAS Simulator is a software tool for analysing SBAS systems performance.

Simulations can be run in single and dual-frequency mode to study the impact of future SBAS

evolutions. It supports a detailed configuration of space segment, ground segment and user

segment. The space segment includes GPS, GALILEO, GLONASS, GEO and custom

constellations. The ground segment is a collection of RIMS over predefined and user SBAS

areas. User segment specifies the geographical region for the simulation. Detailed

configuration of all three segments can be found in sections 4.1, 4.2 and 4.3. The SBAS

performance is simulated through a set of configurable macro models and processing

algorithm set including a detailed ionospheric model. The SBAS Simulator can also work with

real data. Section 4.5 covers macro-model settings.

The tool offers several SBAS performance analyses like XPL, NSE, availability, continuity,

ionosphere modelling and satellite monitoring status. Several other analyses are

implemented. User can also create delta plots and view 3D scene of the simulated situation.

All analyses and tools are detailed in section 5. Results are stored in human readable CSV

files and present in interactive graphs.




3.2 Sample DOP analysis

This section provides step by step guide for a sample DOP analysis.

3.2.1 Running the simulator

The simulator can be run inside the web browser or as a standalone Java application. Before

running the tool, make sure that the operational environment is configured as specified in

Section 2.

Type the address of the SBAS Simulator to the web browser and confirm the security

warning (Figure 2). After the applet loads, the main window of the tool appears (Figure 3).

Figure 3: SBAS Simulator main window.

In the upper part is the Scenario panel allowing user to define, save and load scenarios. Left

panel contains analysis and tool functions, the hearth of the application. The middle area is

dynamic and contains widgets relevant to the current analysis. After the tool starts a short

description of implemented functions can be seen. The description can be reloaded anytime

by clicking the Description button in the Analysis panel.




In the bottom user can set the working and scenario directory (section 4.6). Working

directory is a folder in the hard disk, where temporary and final results are stored. By default

the folder is set to user home directory.

3.3 Constellations and satellites

DOP configuration can be managed by clicking the DOP button in the Analysis panel. The

Description panel is changed to DOP Settings panel, where are all necessary widgets for DOP

analysis.

Constellation Setup panel defines the space segment of the SBAS Simulator. Constellation

can be switched by using the tab at the top (GEO, GPS, GLONASS, GALILEO). A constellation

is used in the simulation, when the Use check box is selected. Particular satellites can be

selected or deselected as well. Default values are used for the purpose of this simulation.

Detailed space segment configuration can be found in section 4.1.

3.4 Simulation time and area

The Time panel shows the simulation length and the time step. Simulation length is the total

length of the simulation and time step is the interval within 2 closest computations. Keep the

default settings (24h simulation with 10-minute step). Time settings are described in section

4.4.

Simulation area is the area where the analysis is performed. It can be set to a region or a

point. For the purpose of this simulation, the default area shall be kept (ECAC square region

with the grid step of 5°). Information about geographical area settings can be found in

section 4.2.1.

3.5 DOP options and analysis

In the right part of the DOP Settings panel is the Simulate DOP button. After clicking on it,

the DOP Simulation Settings window appears (Figure 4).

Figure 4: DOP Simulation Settings window.




Two types of simulation are implemented: Availability and Statistics. I this example, the DOP

availability will be shown. It computes the percent of time when DOP is bellow availability

limits defined in the DOP Simulation Settings window. Simulation is started by clicking the

OK button. The progress bar appears showing the computational details. First satellite

positions are calculated; later ENU coordinates for each point in the region and finally the

DOP availability.

When finished, the graph with DOP availability results is shown (Figure 5).

Figure 5: HDOP availability for ECAC region.

Buttons in the upper-left part of the graph are used to switch among HDOP, VDOP, GDOP,

PDOP and TDOP results.

More information about DOP analysis can be found in section 5.3. Graph features are

detailed in section 6.

4 Settings Before doing any analysis, various parameters and initial conditions shall be set. Initial

settings of the tool are visible after clicking the Settings button in the Scenario panel. There

are more settings specific to each simulation, which are configurable in a separate window

before the analysis starts.




4.1 Space segment settings

Space segment defines constellations, satellites and frequencies used in the simulations. The

main window contains the Constellation Setup panel where constellations can be configured

(Figure 6).

Figure 6: Constellation Setup panel.

In the Constellation Setup panel user can define which constellations and satellites will be

used for the simulation and also define new ones. Four constellations are available after

loading the tool: GEO, GPS, GLONASS and GALILEO. Only GEO and GPS are selected as used

for the simulation by default. To switch among constellations, use the tab panel in the upper

part of the window. It is possible to select the whole constellation to be used or not used by

clicking on the Use check box. The Show PRN numbers check box switches between the

satellite name and its PRN number. Individual satellite can be also selected or deselected

from the simulation using the check box next to it.

4.1.1 Satellite settings

Right-clicking on a specific satellite opens the satellite configuration window (Figure 7).




Figure 7: Satellite configuration window for GPS B2.

User can edit satellite frequencies, its almanac and specify the monitoring conditions. Those

features are in detail described in sections 4.1.1.1, 4.1.1.2 and 4.1.1.3.

4.1.1.1 Satellite frequencies

SBAS Simulator can work in the dual frequency mode in which two different frequencies for

each satellite can be specified. Those frequencies can be set in the satellite frequencies

editor (Figure 8).

Figure 8: Satellite frequency editor.

User can select pre-defined frequency and its corresponding value appears. In dual

frequency mode, two different frequencies for a satellite shall be selected; otherwise the

SBAS Simulator will not start the simulation. Ranging is configurable for each frequency.

When ranging is available for specific frequency, satellite is visible in that frequency. Ranging

can be turned on/off of specific ranging loss can be defined. Those settings are available

through the Ranging settings window (Figure 9) after clicking the ranging button in the

satellite frequencies editor.




Figure 9: Ranging settings window.

By default the ranging is always available and there is no loss of the satellite signal. User can

define two different types of signal loss: temporary and random. Temporary data loss

specifies time intervals when the ranging is not available (Figure 10). Several time intervals

can be specified. A new interval is added clicking the Add time interval button. Interval is

deleted clicking the red cross next to the value fields. It is also possible to delete all time

intervals through the Delete all intervals button.

Figure 10: Temporary ranging data loss.




Random data loss specifies the probability of the signal loss. User specifies the value in

percent (Figure 11). During the simulation the tool decides if the signal will be available or

not based on the integrated random generator.

Figure 11: Random data loss.

4.1.1.2 Satellite almanacs

SBAS Simulator supports 3 different types of almanacs, one of which has 2 subtypes:

Almanac with Keplerian elements (2 different subtypes)

o with Longitude of Ascending Node of Orbit Plane at Weekly Epoch (LANOPWE

for short)

o with Right Ascension of the Ascending Node (RAAN for short)

Almanac with XYZ (ECEF) elements

GLONASS Almanac

Satellite almanacs can be edited in the Almanac Editor window. Figure 12, Figure 13, Figure

14 and Figure 15 contain examples of Almanac Editor windows for all types of supported

almanacs. Table 4 shows examples of where the values of the fields can be found.




Figure 12: Almanac with Keplerian elements with Longitude of Ascending Node of Orbit Plane at Weekly Epoch (LANOPWE) example.

Figure 13: Almanac with Keplerian elements with Right Ascension of the Ascending Node (RAAN) example.




Figure 14: Almanac with XYZ (ECEF) elements example.

Figure 15: GLONASS almanac example.




Element/field Included in type of

almanac Source example

health Keplerian with LANOPWE, Keplerian with RAAN, XYZ (ECEF)

YUMA almanac

eccentricity

Keplerian with LANOPWE, Keplerian with RAAN

YUMA almanac

semi-major axis [m]

YUMA almanac (SQRT(A) (m 1/2) in the almanac, square root of semi-major axis in the almanac (here the square root is squared))

Longitude of ascending node at weekly epoch [rad]

Keplerian with LANOPWE YUMA almanac (Right Ascen at Week(rad) in the almanac)

Right ascension of ascending node [rad]

Keplerian with RAAN TLE (in degrees in TLE (here in radians))

mean anomaly [rad]

Keplerian with LANOPWE, Keplerian with RAAN

YUMA almanac

orbit inclination [rad] YUMA almanac

argument of perigee [rad] YUMA almanac

toa Week

RINEX 3.02 GNSS Navigation Message File – GPS Data Record (GPS Week # (to go with TOE) in RINEX)

toa SOW

RINEX 3.02 GNSS Navigation Message File – GPS Data Record (Toe Time of Ephemeris in RINEX)

position X [km]

XYZ (ECEF)

RINEX 3.02 GNSS Navigation Message File – SBAS Data Record

position Y [km]

position Z [km]

velocity X dot [km/s] RINEX 3.02 GNSS Navigation Message File – SBAS Data Record (for practical reasons these fields are left 0 when loading from RINEX)

velocity Y dot [km/s]

velocity Z dot [km/s]

X acceleration [km/(s*s)]

Y acceleration [km/(s*s)]

Z acceleration [km/(s*s)]

health (1 means healthy, 0 means unhealthy)

GLONASS

GLONASS almanac (.agl)

longitude of ascending node [radians]

GLONASS almanac (.agl; Lam in the almanac, in semi-cycles in the almanac (here in radians))

correction to mean inclination of orbit [radians]

GLONASS almanac (.agl; dI in the almanac, in semi-cycles in the almanac (here in radians))




correction to mean draconic period [seconds]

GLONASS almanac (.agl; dT in the almanac)

rate of change of draconic period [seconds per cycle]

GLONASS almanac (.agl; dTT in the almanac)

eccentricity of the satellite orbit

GLONASS almanac (.agl; E in the almanac)

argument of perigee [radians] GLONASS almanac (.agl; w in the almanac, in semi-cycles in the almanac (here in radians))

year GLONASS almanac (.agl)

GLONASS day GLONASS almanac (.agl; made using day, month and year from the almanac)

Second of day GLONASS almanac (.agl) Table 4: Almanac fields and examples of sources of values.

4.1.1.3 Satellite monitoring conditions

Each satellite in the SBAS Simulator can have two monitoring states: monitored and not

monitored. When the satellite is monitored, it is used for the SBAS Simulation otherwise not.

Monitoring depends on the number of actual visible RIMS. It also depends on satellite

ranging and the RIMS availability. When a satellite signal is lost or RIMS is not available, the

RIMS for that satellite is not visible even if it is geometry shows the opposite. RIMS have

several types (A, B, C, D, E and F). Satellite is considered monitored when it sees at least

specific number of each RIMS type. This configuration is done through the Monitor settings

window as shown in Figure 16.

Figure 16: Monitor settings window for satellite B2.




4.1.2 Adding and removing satellite from a constellation

By pressing the Add a satellite button a satellite can be added into the constellation. By

pressing Remove selected satellites, all selected satellites are removed from the constellation.

Both of these buttons can be found in the Constellation Setup panel (Figure 6).

4.1.2.1 Adding a satellite to the constellation

Each constellation can have a limited number of satellites. Four default constellations and

custom constellations have different limits for the maximum number of satellites (see Table

5). Once the maximum number of satellites has been reached, no new satellites can be

added to the constellation before some of the satellites are removed first. The total number

of satellites in all custom constellations cannot be more than 63.

Constellation Maximum number of

satellites Available PRNs

GEO 40 120 – 159 (both inclusive)

GPS

37

1 – 37 (both inclusive)

GLONASS 38 – 74 (both inclusive)

Galileo 75 – 111 (both inclusive)

Custom constellation 40 in one constellation,

63 in total in all constellations

112 – 119 (both inclusive), 160 – 214 (both inclusive)

Table 5: Maximum number of satellites for different constellations and available PRNs.

Constellation Constrains for satellite names

GEO

Length of the name of the satellite must be at least 1 character and at most 10 characters.

GLONASS

Galileo

Custom constellation

GPS (when orbit slots are available)

Name must be in the format XYZ or XY, where X is a letter, an element from {‘A’, ‘B’, ‘C’, ‘D’, ‘E’, ‘F’}, Y is a

number between 1 and 9 (both inclusive), Z is a letter, an element from {‘A’, ‘F’}. Examples: A6, D2F, F1A.

For a particular pair (X, Y) it is not possible to have an XYZ (for any Z) and XY satellite in the constellation at

the same time. It is possible to have both XYZ satellites in the constellation though. Example: When A6F is in the constellation, A6 cannot be added, A6A

can be added however. Table 6: Names of satellites rules.




Before entering the almanac of a new satellite, the format of the almanac has to be selected

(see Figure 17). Three different almanac types are supported (see section 4.1.1.2). Note that

Keplerian with Omega means Keplerian with RAAN and Keplerian with Omega0 means

Keplerian with LANOPWE.

After selecting one of the almanac formats a window similar to Figure 12, Figure 13, Figure

14 or Figure 15 is opened. Unlike in those windows, the name and PRN of the new satellite

can be edited. Name of the satellite cannot be edited if the user is adding a satellite to a

default GPS constellation that does not include slots. Both name and PRN of the new

satellite are prefilled with the first available name/PRN for that constellation. Each of the

constellations has a limited range of available PRNs. PRNs outside of the range cannot be

used in the constellation (see Table 5). There are constrains regarding the names of the

satellites in particular constellations, these are mentioned in Table 6. Satellites in the GEO

constellation can also be added specifying just the satellite’s longitude.

Figure 17: Almanac format selection screen.

4.1.2.2 Removing satellites from the constellation

It is not possible to remove all satellites from a constellation; a constellation shall have at

least one satellite. Removing all satellites is done via the Remove constellation button (see

4.1.3.2).

The Remove selected satellites button will not work when no satellites are selected. A

confirmation dialog is shown before satellites are removed from the constellation.

4.1.3 Adding and removing a constellation

Besides the four default constellations in the simulator (GEO, GPS, GLONASS and Galileo),

new constellations can be added via the Add constellation button. Custom constellations can

be removed from the simulator by pressing the Remove constellation button. Both of these

buttons are in the Constellation Setup panel (see Figure 6).




4.1.3.1 Adding a constellation

It is not possible to add new constellations if the maximum number of satellites in custom

constellations (63) has been reached (see Table 5). A new constellation can be added either

from a file or from parameters entered by the user (see Figure 18).

Figure 18: Add a new constellation dialog window.

Only the first field (name) is used in both cases. Name has to be between 3 and 10

characters long (both inclusive) and it is not possible to use a name that is the same as a

name of a constellation already present in the SBAS Simulator. All other fields are only used

when adding a constellation from user parameters.

When creating a new constellation from user defined parameters the number of orbital

planes value has to be between 1 and the number of satellites field (both inclusive). Every

plane will have nSat / nOP (rounded down) satellites, where nSat is the value of the number

of satellites field and nOP is the value of number of orbital planes field. When nSat % nOP is

not equal to zero but is equal to some x, first x planes will have one more satellite than nSat

/ nOP (rounded down). How the Keplerian elements are set for each satellite in a new

constellation can be seen in Table 7.




Keplerian element of a new satellite (see Figure 12)

value for i-th satellite in the new constellation (see Figure 18)

PRN i-th available PRN not already used in a custom constellation (see Table 5)

name

XXX YY where

XXX is the first three letters of the constellation name, always upper case (even if the name of the constellation is not in upper case)

YY is i formatted to 2 characters (e.g. if i is 4, YY would be 04)

Example:

constellation name is MyConstellation

i is 7

name of the satellite would be MYC 07

health 0

eccentricity value of field eccentricity

semi-major axis [m] value of the field semi-major axis [m]

Longitude of ascending node at weekly epoch [rad]

raFirst + 2*pi*j / nPlanes where

raFirst is the value of the field Longitude of the first plane [rad]

j is the number of the satellite’s plane (for 1st plane j is 0)

nPlanes is the value of the field number of orbital planes

mean anomaly [rad]

2*pi*k / sIP[j] Where

k is the number of satellite in the plane (1st satellite in the plane has k equal to 0)

sIP[j] is the number of satellites in plane j, where plane j contains the satellite i

orbit inclination [rad] value of field orbit inclination [rad]

argument of perigee [rad] 0

toa Week value of field toa Week

toa SOW value of field toa SOW Table 7: Keplerian element values for a satellite in a new constellation added from user parameters.




When adding a new constellation from a file, user shall choose the base constellation. Unlike

rewriting an existing default constellation (see section 4.1.5), the loaded constellation is put

in a new tab in the Constellation setup panel (see Figure 6). When based on GPS, loading of a

new constellation will not change the Simulation start time (see section 4.4), unlike rewriting

the default GPS constellation (see section 4.1.5.2). Satellites’ names and PRNs are set

according to rules in Table 7 even if PRNs or names are available (through RINEX or TLE files).

Loading fails if a file contains too many satellites (see Table 5).

When loading a new constellation from a QZSS based file, the file has to be a RINEX version

3.02 or 2.12. RINEX 3.02 may be mixed, in that case only QZSS satellites are loaded from it. If

a RINEX contains multiple instances of the same QZSS satellite, the instance with newest GPS

Week and Time of Ephemeris is loaded. QZSS entries in a RINEX file contain information used

to create almanacs of type Keplerian with LANOPWE.

4.1.3.2 Removing a constellation

Only custom constellations can be removed. When a custom constellation is present in the

simulator, pressing the Remove constellation button will open a dialog window where the

user can choose a constellation to be deleted.

4.1.4 Setting the constellation to the default state

A constellation can be reset to its default values using the Default button in the Constellation

Setup panel (see Figure 6). For a default constellation (GEO, GPS, GLONASS or Galileo)

default values are those set when the simulator has been launched. For a custom

constellation default values are those set when the constellation was added to the simulator.

When the reset constellation σ value is checked (see Figure 19) sigma values are reset to the

original state (see 4.5.1).

When reset constellation data is checked all parameters under Constellation settings at the

top of Constellation Setup panel (see Figure 6) are reset to defaults. Also the composition of

the constellation is reset: all satellites removed from the original constellation are restored

and all satellites added on top of the original constellation are removed. Also all settings of

each satellite (see section 4.1.1) are reset to default.




Figure 19: Default constellation parameters dialog.

When neither of the checkboxes is checked and OK is pressed, the effect is the same as

pressing Cancel. A warning window may appear informing that the ephemeris time of the

constellation has been changed as a result of resetting the constellation to default values.

4.1.5 Constellation source

Each of the four default constellations (GEO, GPS, GLONASS and Galileo) can be overwritten.

By pressing the Constellation source button in the Constellation Setup panel (see Figure 6) it

is possible to select the source of the default constellation.

4.1.5.1 Source of GEO constellation

In the GEO Constellation window (see Figure 20) four different sources of GEO constellation

can be chosen:

GEO nominal constellation

GEO constellation decoded from an MT17 message

GEO constellation from a RINEX file

GEO constellation from a TLE file

Figure 20: GEO constellation source window.




When loading from MT17, satellite names are set to generic GEO XX, where XX is a number

starting from 01. Only the X, Y and Z coordinates and the PRN are taken from the message,

other information, like the velocity, is ignored and set to 0 for all dimensions and for all

satellites.

TLE files used for loading a GEO constellation have to contain on the 0th line the satellite

name and the PRN. An example of such a record with name and PRN both on the 0th line can

be seen in Figure 21. If the TLE file contains multiple instances of the same satellite (satellite

is identified by its PRN), only the first record is taken and all subsequent all ignored. TLE files

don’t contain information about a satellite’s health, health of all satellites loaded from a TLE

thus have their health set to 0. Almanacs created for the satellites from data in a TLE file are

Keplerian with RAAN (see 4.1.1.2).

Figure 21: An example of a record in a TLE file containing both the name and the PRN of a satellite.

RINEX GNSS Navigation Message Files with GEO satellites (named SBAS satellites in RINEX)

contain data about GEO satellites from which XYZ (ECEF) almanacs are created (see 4.1.1.2).

Only RINEX 3, 3.01 and 3.02 are supported when loading GEO satellites. The Satellite System

(included in the header of a RINEX file) can be either S (SBAS Payload) or M (Mixed). For

mixed satellite system, only GEO satellites are loaded from a RINEX file. Acceleration and

velocity in the RINEX are ignored for all dimensions and are set to 0 for each satellite. When

a RINEX file contains multiple records of the same satellite, the record with the newest Time

of Clock is loaded. However that time is not loaded from the RINEX, because the XYZ (ECEF)

almanac does not contain information about the time (see Figure 14). Instead the ephemeris

time of GEO is internally set to the middle of the simulation. PRN of a satellite is created by

adding 100 to satellite number from RINEX. Satellite names are set to GEO XX the same way

as in the case of loading the MT17.

4.1.5.2 Source of GPS Constellation

In the GPS Constellation window (see Figure 22) seven different sources of GPS constellation

can be chosen:

GPS current constellation

GPS nominal constellation (SPS 2008)

GPS expandable constellation (SPS 2008)

Load from YUMA file

Load from SEM file

Load from RINEX file




Download from the internet

Figure 22: GPS constellation source window.

Current constellation is loaded from the latest YUMA almanac on the internet. Simulation

start time (see 4.4) is also changed to the current time when loading the latest YUMA

almanac.

When loading from a local YUMA or SEM file, satellite names (slots) are disabled (only PRNs

can be viewed). YUMA and SEM file contain almanacs of satellites in Keplerian with

LANOPWE format (see 4.1.1.2). GPS week number rollover is used because the GPS week

contained in a YUMA or SEM file is modulated by 1024. Thus week number rollover set to 1

will result in 1024 being added to the week from the YUMA/SEM file to create the real GPS

week. Simulation start time (see 4.4) is changed to the time of the 1st satellite that was

loaded from the file.

Loading a GPS constellation from a local RINEX is possible for RINEX version 2.11, 2.12, 3,

3.01, 3.02. For RINEX 3.xx the RINEX GNSS Navigation Message File Header’s Satellite System

can be GPS or Mixed. When the header is mixed, only GPS satellites are loaded from the

RINEX file. When the RINEX file contains multiple records with the same satellite, the record

with the newest GPS Week and Time of Ephemeris is loaded; all other records of the same

satellite are ignored. RINEX with GPS satellites contain data for almanacs in the Keplerian

with LANOPWE format (see 4.1.1.2). As with loading a GPS constellation from a local YUMA

or SEM file, satellite names (slots) are disabled if the GPS constellation is loaded from a local




RINEX file. Simulation start time is also changed in a similar way as in the case of loading the

YUMA or SEM file.

When loading the GPS constellation from the internet a YUMA file for the specified day is

downloaded. The simulation start time (see 4.4) is changed to 0:00:00 UTC of that day.

4.1.5.3 Source of GLONASS Constellation

In the GLONASS constellation window (see Figure 23) three different sources of the

GLONASS constellation can be chosen:

GLONASS current constellation

GLONASS nominal constellation

Load from .agl file

Figure 23: GLONASS Constellation source window.

Current constellation is loaded from the current .agl almanac on the internet. Almanacs of

the loaded satellites are in GLONASS almanac format (see 4.1.1.2).

When loading from a local .agl file, PRN of a satellite is created by taking the number of the

spacecraft (included in the .agl file) and adding 37 to it. Thus a satellite from the .agl file with

spacecraft number equal to 1 will get a PRN equal to 38. When an .agl file contains multiple

records of the same satellite (from different times), only the first record of such a satellite is

loaded. Names of satellites loaded from an .agl file are created using the spacecraft number

from the .agl file: every satellite has a name equal to GLO XX, where XX is the spacecraft

number in two digit format. Thus, for example, a satellite with spacecraft number 6 will be

named GLO 06.

4.1.5.4 Source of Galileo constellation

A Galileo constellation can be loaded from 4 different sources (see Figure 24):

Galileo current constellation




Galileo nominal constellation

Galileo expandable constellation

Galileo IOV 4 satellites

Figure 24: Galileo constellation source window

Current constellation is loaded from a RINEX file on the internet. PRNs of the satellites are

created by adding 74 to the satellite number from the RINEX file. Thus a Galileo satellite in a

RINEX file with satellite number 11 will have its PRN equal to 85. Names of the satellites are

in the format EXX, where XX is the satellite number from the RINEX file. If a RINEX file

contains multiple records of the same satellite, the records with the newest GAL Week and

Time of Ephemeris is loaded. Almanacs of the loaded satellites are in the Keplerian with

LANOPWE format (see 4.1.1.2).

4.1.6 Constellation settings

Each constellation has specific settings that define general characteristics and can also have

effect on individual satellites. The Constellation Settings window (Figure 25) is opened after

clicking the Constellation settings button in the Constellation Setup panel (Figure 6).




Figure 25: GPS constellation settings window.

Signal usage specifies how the signal from individual satellites will be used. The signal can be

used for three different purposes: SBAS distribution, ranging and ionosphere. When the

SBAS distribution check box is selected, all satellite in the constellation will broadcast the

SBAS signal. The SBAS signal is broadcasted without any interruption even if the satellite

signal is lost for ranging. This setting is set by default only for GEO satellites as they are

predetermined to provide the SBAS corrections. Anyway this setting can be set for any other

constellation. The SBAS Distribution Mask field configures the minimum elevation of the

SBAS satellite in order to receive corrections. The Ranging check box specifies if the satellite

signal is used for ranging. It that case the satellite signal enters all simulations except the

ionosphere which is treated separately (when the Ionosphere check box is selected). Satellite

signal affects both ranging and ionosphere. When SBAS Simulator is in dual frequency mode,

the satellite signal is available when it is available on both frequencies. In single frequency

only the first frequency is considered. The availability of frequencies is affected by each

frequency ranging as specified in 4.1.1.1.

Each constellation can specify frequencies and ranging the same way as in the case of

individual satellites (see 4.1.1.1). Constellation frequencies do not affect individual satellite

frequencies if the user does not specify it. For that purpose two separate check boxes are

present in the Constellation frequencies panel. When the Apply frequencies… check box is

selected, the constellation frequencies are automatically copied to all satellites in the




constellation. When the Apply frequency ranging… check box is selected, the constellation

frequency ranging settings are automatically copied to all satellites in the constellation.

Constellation also specifies monitoring conditions the same way as for individual satellites

(see 4.1.1.3). If the Apply monitoring conditions… check box is selected, constellation

monitoring conditions will be also copied to all satellites in the constellation.

4.1.7 Frequency mode and frequency values

SBAS Simulator main window contains Frequency panel where frequency mode and

individual frequency values can be set (Figure 26).

Figure 26: Frequency panel.

SBAS Simulator can run in two modes. By default, the single frequency mode is used.

Satellite frequencies are treated separately and analysis equations take into account the

dual frequency solution. In the single frequency mode only the first satellite frequency is

used for the simulation.

SBAS Simulator contains several different frequencies: L1, L2, L5, G1, G2, E1, E6, E5a and E5b.

Each frequency has specific frequency value which can be changed by the user (Figure 27).

Figure 27: Frequency values editor.




Frequency values affect the solution in the dual frequency mode through the dual frequency

factor as defined in equation (8). In the single frequency mode, frequency value affects only

the Diono parameter in ionospheric computation.

4.2 User segment settings

User segment defines the geographical simulation area, the user mask and service settings.

All are accessible through the main window of the SBAS Simulator (Figure 28).

Figure 28: User segment settings.

4.2.1 Geographical area settings

Simulation area specifies the region where the simulation is to be performed. It can be se to

a region or to a point (Figure 29).

Figure 29: Simulation area.




For the point simulation user specifies the coordinates which are set to Paris by default.

When region simulation is chosen, it is possible to select region from a predefined list or

define a custom region. Predefined regions are: ECAC area, ENP, Africa, Europe and Africa,

North America, Japan, India, Russia and World.

ECAC area is set as default. For the custom region, user defines a region name and a border.

Parameter min lon is the longitude where simulation starts and then it goes to the east until

it reaches the max lon, where it stops. Southern border of the simulation area is bounded by

min lat and northern by max lat. Parameter Grid step is the distance (in longitude or latitude)

between 2 closest points in the area. Available values for grid step are 0.5°, 1°, 2.5°, 5°, 10°,

15° and 30°. The default value is 5°. The larger the region and the lower the grid step, the

more time the simulator needs to perform an analysis.

4.2.2 User mask settings

User mask angle defines the minimal elevation below which the satellite will not be used.

Available values are 2°, 5°, 10°, 15° and 30°. The default value is 5°.

4.2.3 Service settings

Service settings (Figure 30) have impact on availability and continuity analyses. Several

services are defined: AVPI, AVPII, CATI, LPV200 and NPA. They specify the HAL and VAL. User

can also define its custom services.

Figure 30: Service settings.

4.3 Ground segment settings

Ground segment consist of various RIMS distributed over the simulated region. The RIMS

panel (Figure 31) is accessible through the main window of the SBAS Simulator. Clicking the

RIMS location map button opens a global view of selected and available RIMS. Other two

buttons allow selecting defined RIMS (4.3.1) and the RIMS error distribution (4.3.4).




Figure 31: RIMS panel.

4.3.1 RIMS selection

RIMS selection window (Figure 32) shows all defined RIMS together with a check box. When

the check box is selected, RIMS is used in the simulation, otherwise not. Stations are

grouped into RIMS networks, which collect RIMS over similar geographical area. By default,

the following RIMS networks are present: EGNOS, MEDA, East of Europe, Africa A and B,

Africa C, MIDAN, WAAS, additional RIMS and user defined RIMS. User defined RIMS serve for

defining custom RIMS. After clicking the Define RIMS button, user specifies the RIMS name

and its coordinates.

Figure 32: RIMS selection window.




4.3.2 RIMS configuration

Each RIMS can be configured separately. The RIMS configuration window (Figure 33) is

opened after right clicking on a particular station. At the top is displayed RIMS information

and below the configuration panel containing settings for each of the RIMS types (A, B, C, D,

E and F). If the RIMS type is selected, it is active for the simulation, otherwise not. Note that

RIMS types are also part of satellite monitoring conditions (4.1.1.3). RIMS type configuration

window (Figure 34) opens after clicking the Configure button next to the RIMS type. RIMS

type configuration can be divided in RIMS data loss (4.3.2.1), RIMS data availability (4.3.2.2)

and RIMS error bounds (4.3.2.3).

Figure 33: RIMS configuration window.




Figure 34: RIMS type configuration window.

4.3.2.1 RIMS data loss

RIMS data loss follows the same idea and same settings as ranging data loss (4.1.1.1). When

RIMS is lost, it is not visible by the satellite and cannot be used for satellite monitoring and

for the IPP computation.

4.3.2.2 RIMS data availability

RIMS availability is similar to RIMS data loss. When RIMS is set as not available, it is not seen

by the satellite and is not used for IPP computation. RIMS unavailability is set by a local mask

and by local time constraints. RIMS elevation mask specifies the local horizon. A RIMS can be

seen by a satellite only when it is above the local horizon. By default the horizon is set to 5°.

It is possible to add more complex horizons through the RIMS elevation settings window

(Figure 35).




Figure 35: RIMS elevation mask.

RIMS local time unavailability is set through the RIMS local time unavailability window

(Figure 36). By default, no unavailability periods are defined. The specified time is a local

time for the given RIMS, which is computed from the station longitude. RIMS can be seen by

a satellite only when a satellite is above the RIMS horizon and the station is available at the

given time.

Figure 36: RIMS local time unavailability window.




4.3.2.3 RIMS error bounds

RIMS error bounds define the error contribution to the overall satellite error. More details

on the algorithm can be found in [RD2]. By default RIMS is treated as a fault free receiver

with no error contribution. Errors are divided in the interference, noise for MEO, noise for

GEO, multipath and troposphere. User can specify all error contributions. Troposphere and

multipath errors are defined in [RD3]. Noise errors are specified just for a single frequency

solution. For dual frequency solution the value is multiplied by appropriate dual frequency

factor (2.59 for standard L1 and L5). The equation (8) gives details on computing the dual

frequency factor for any frequency combination.

4.3.2.4 RIMS global configuration

In the RIMS configuration window (Figure 33) there is the Configure button next to the

“Global configuration” text. After clicking the button user can configure the RIMS data loss,

availability and error bounds that are not specific to some RIMS type. Those settings can be

applied to all RIMS types if the appropriate check box is selected at the bottom. For example

the same horizon can be easily copied to all RIMS types.

4.3.3 RIMS network configuration

Apart from a global configuration of specific RIMS, it is also possible to globally configure

RIMS from one network. Each RIMS network panel contains a small “c” button that opens a

global configuration window. It contains the same configuration fields as individual station.

At the bottom is a checkbox that makes a copy of the global settings to all RIMS in the

network. This way the user can easily modify a value that is the same for all RIMS. It is

recommended to do first the global network configuration, then the global RIMS

configuration (4.3.2.4) and finally configuration for each RIMS type.

4.3.4 RIMS error distribution

RIMS error distribution specifies the algorithm how particular RIMS errors are applied to the

overall satellite error. It is possible to select between the equal and weighted error

distribution. Details on the algorithm can be found in [RD2].

Figure 37: RIMS error distribution.




4.4 Time settings

In the SBAS Simulator main window is the Time panel which shows the simulation length and

the simulation time step. The simulation length is the total length of the simulation.

Simulation time step specifies the interval between two consecutive simulations. Those

values can be set in the Time Configuration window (Figure 38).

Figure 38: Time configuration.

Advanced time settings (Figure 39) can be opened by clicking on the Advanced button. User

can define simulation length based on orbital period of satellites in constellations or set the

custom simulation length. Simulation time step is also configurable. Finally the start

simulation time can be specified filling the GPS week and SOW fields. The start time is also

displayed in local time and in UTC. When the real satellite ephemeris is used, it is the user

responsibility to set the correct start time of the simulation.




Figure 39: Advanced time configuration.

4.5 Macro-model settings

Macro-model settings contain configuration related to different macro models used by the

SBAS Simulator. The Macromodel settings panel can be found on the main window of the

tool (Figure 40). Sigma values, UDRE model and DFRE model contain information related to

particular constellation (sections 4.5.1 - 4.5.3). Other settings are global for the whole

application (4.5.4 - 4.5.7)

Figure 40: Macromodel settings panel.




4.5.1 Constellation sigma values

Constellation sigma values contain error over bounds related to specific constellation. Figure

41 shows the situation.

Figure 41: Sigma values for GPS.

Following sigma values are defined:

σUDRE – Editable only in single frequency mode and when the UDRE interpolation is

not used (4.5.2).

σDFRE – Editable only in dual frequency mode and when the DFRE interpolation is not

used (4.5.3).

σUIVE – Editable only in single frequency mode and when the constant user UIVE value

is used (4.5.4).

σnoise – Part of the total satellite noise.

σclock – Part of the total satellite noise.

σorbit – Part of the total satellite noise.

σsystem – Overall constellation system error.

4.5.1.1 Satellite error bound for single frequency mode

For the single frequency mode the overall satellite residual is computed as:

, (1)

where:

σi,sf is the total satellite error over bound for single frequency,




σi,flt is defined in MOPS [RD3],

σi,UIRE is defined in MOPS [RD3],

σi,air,sf is the air residual for single frequency specified in equation (2),

σi,tropo is defined in MOPS [RD3],

σi,RIMS is the error contribution from RIMS as defined in [RD2],

σi,system is the overall constellation system error (4.5.1).

The σi,air,sf is computed as:

(2)

, (3)

where

σi,multipath is defined in MOPS [RD3],

σi,noise, σi,clock and σi,orbit are part of the total satellite noise (4.5.1).

4.5.1.2 Satellite error bound for dual frequency mode

For the dual frequency mode the overall satellite residual is computed as:

, (4)

where

σi,DFC is the model variance for dual frequency residual error as specified in equation

(5),

σi,iono is the ionospheric residual error for dual frequency services as specified in

equation (6),

σi,air,df is the air residual for double frequency specified in equation (7),

σi,tropo is defined in MOPS [RD3],

σi,RIMS is the error contribution from RIMS as defined in [RD2],

σi,system is the overall constellation system error (4.5.1).

The σi,DFC is computed as:

, (5)

where parameters in the equation are specified in section 4.5.3.




The σi,iono is computed as:

, (6)

where Fpp is defined in MOPS [RD3].

The σi,air,df is computed as:

, (7)

where fdual is dual frequency factor defined as:

, (8)

where f1 is the first frequency and f2 is the second frequency. For L1 and L5 the dual

frequency factor is 2.59.

4.5.2 UDRE model

UDRE model specifies how the satellite UDRE is computed. This model is available only in the

single frequency mode. User can select the algorithm for σUDRE computation and also the σflt

algorithm (Figure 42).

Figure 42: UDRE model.

The value of σUDRE can be set to constant or determined by the interpolation. The constant

value is set through the dialog on Figure 41. The interpolation is done in the window on




Figure 43. During the interpolation, the σUDRE is set to the value which is based on number of

RIMS that monitor a specific satellite.

Figure 43: Sigma UDRE interpolation.

The computation of σflt is described in MOPS [RD3]. User is able to specify MT27 and epsilon

values for LTC.

4.5.3 DFRE model

DFRE model specifies how the satellite DFRE is computed. This model is available only in the

dual frequency mode. User can select the algorithm for σDFRE computation and also the σDFC

algorithm (Figure 44).




Figure 44: DFRE model.

The value of σDFRE can be set to constant or determined by the interpolation. The constant

value is set through the dialog on Figure 41. The interpolation is done similar way as in the

case of σUDRE (Figure 43). The computation of σDFC is described in equation (5). User is able to

specify epsilon values for the DFC model.

4.5.4 Ionospheric model

SBAS Simulator has 4 different ionospheric models:

1. IONEX ionospheric model (see 4.5.4.1)

2. Geometric GIVE model (see 4.5.4.2)

3. GPS ionospheric model (see 4.5.4.3)

4. Constant user UIVE model (see 4.5.4.4)

Figure 45: SBAS Simulator ionospheric models.

The task of the ionospheric models is to provide GIVE and UIVE values based on defined

algorithms. Apart from the GPS ionospheric model, the σUIRE is computed using the equation




A-43 of MOPS [RD3]. Ionospheric models are used only in the single frequency mode. In the

dual frequency mode the ionospheric-free solution is used.

4.5.4.1 IONEX model

The IONEX ionosphere model is described in detail in [RD4]. The GIVE computation is based

on a linear function between the turning point and the point at storm conditions:

, (9)

where a is the slope, Dfactor is the degradation factor and m is the offset. If the Dfactor value is

not between the turning point and storm condition, the GIVE is set to constant.

The relation between GIVE and σGIVE is specified by the following equation:

(10)

Degradation factor is computed as:

, (11)

where Dmonitor reflects the spatial distribution of IPPs around and IGP and Diono takes into

account the gradient of total electron content. More details can be found in [RD4].

SBAS Simulator provides detailed configuration of the following model subcomponents (see

also Figure 46):

general ionosphere settings

Dmonitor settings (includes D#IPP and DGEO settings)

Dfactor settings

ionospheric scintillation settings (includes polar and two equator regions); can be

switched off

Diono settings (includes the IONEX file location)




Figure 46: IONEX ionospheric model.

The IONEX file must be provided or simulations dependent on the ionosphere will fail. User

is responsible that data in the IONEX file corresponds to the simulation interval.

4.5.4.2 Geometric GIVE model

Geometric model takes into account ionospheric scintillations and spatial distribution of IPPs

around an IGP. When scintillation happens to a particular IPP, this IPP is not present in the

simulation. It is possible to disable scintillation for the simulation. The spatial distribution

(Dmonitor settings) can change a specific IGP to be not monitored. The computation of Dmonitor

can be switched off (only IGP radius is taken into account). The σGIVE value at each IGP is

based on the number of surrounding IPPs. All values can be configured through the

geometric model window (Figure 47).




Figure 47: Geometric ionospheric model.

4.5.4.3 GPS ionospheric model

GPS ionospheric model is the standard Klobuchar ionospheric model (Figure 20-4 of [RD5]).

User can configure α and β parameters of the model (Figure 48). The σUIRE computation is

explained in J.2.3 of MOPS [RD3].

Figure 48: Klobuchar ionospheric model configuration.




4.5.4.4 Constant user UIVE model

When no ionospheric model is used, user provides a constant σUIVE value for each

constellation (Figure 41).

4.5.5 SBAS settings

The total error over bound as specified in equation (1) can be computed using the real data

from internet, local EMS or RINEX files. In this case real SBAS messages are used and they are

processed using MOPS [RD3]. By default, simulation macro models are used. User can switch

to the real data mode in the SBAS Simulation Settings dialog (Figure 49).

Figure 49: SBAS simulation settings.

For the real data simulation it is possible to select between the PA and NPA mode. User is

able to select from different SBAS sources as explained in the following two subsections.

4.5.5.1 Loading SBAS messages from internet

After clicking the Set satellite button user shall choose the augmentation satellite. Internet

SBAS messages are taken from ESA EMS server and only EGNOS satellites are available (PRN

120, PRN 124 and PRN 126).

After confirming the SBAS simulation settings, user has to make sure that the simulation

does not run in the future. SBAS messages are stored on the server as a collection of EMS

files. Each file contains 1-hour record of satellite augmentation broadcast. Every hour new

files are stored on the server with messages from the past hour. Simulation should end at

most an hour before current time so no messages are lost. It is safer to keep the interval

larger. User shall also verify that GPS constellation reflects the real situation for the

simulation time.

EGNOS satellites broadcast augmentations for Europe. The simulation region shall be set to

the ECAC region or to the part of it.




4.5.5.2 Loading local EMS or RINEX files

When loading local files with SBAS messages, simulation start time and simulation length shall be checked. GPS almanac shall correspond to the simulation time. Before starting the simulation, it is recommended to go through the following steps:

1. Choose the start time (day of year, year). 2. Download GPS almanac for that date. 3. Adjust simulation start time (if needed). Simulation start time should differ from GPS

time of applicability at most by a week. 4. Set the simulation length. 5. Select local data using the Set EMS files or Set RINEX files button.

4.5.6 XPL dynamic conditions

User dynamic conditions can be taken into account when computing the XPL. Three different

approaches are implemented:

1. No dynamic conditions – XPL is computed as usual.

2. Fixed dynamic conditions – yaw, pitch and roll angles are specified and will be fixed

for the simulation.

3. Worst dynamic conditions – yaw, pitch and roll angle intervals are specified and the

worst solution is presented.

Figure 50: Dynamic conditions for XPL.

Yaw, pitch and roll angles are Euler angles specifying the position of a user plane (Figure 51).

All three angles are set to 0 when the plane is heading to north and the local z-axis points

upwards.




Figure 51: Yaw, pitch and roll angles.

The position of the plane defines the local horizon. The local horizon adds additional user

mask to the simulation. Satellite is not visible when it is below the local horizon.

4.5.6.1 Fixed dynamic conditions

Fixed dynamic conditions specify the position of the user plane. The same plane is used for

all user positions. The plane position is defined by yaw, pitch and roll angles which are

configurable (Figure 52).

Figure 52: Fixed dynamic conditions configuration.

Plane Euler angles define the local horizon that affects the visibility of satellites. XPL

computation takes this additional mask into account.

4.5.6.2 Worst dynamic conditions

Worst dynamic conditions move the user plane within the specific interval. User can define

the interval and the moving step for each angle (Figure 53).




Figure 53: Worst dynamic conditions configuration.

During the simulation the plane is moving within defined intervals and for each plane

position the XPL is computed. After XPL was computed for all positions, the worst value is

stored. The position of the plane for the worst solution can be different at different user

locations. The simulation can take more time when using the worst dynamic conditions.

4.5.7 Navigation solution unknowns

By default, the system error algorithms use the weighted solution with 4 unknowns as

defined in MOPS [RD3]. When multiple constellations are used, it is possible to make the

weighted solution with 5 unknowns.

Figure 54: Navigation solution unknowns.

The system broadcasts corrections with respect to each constellation system reference time.

The inter constellation time offset and receiver inter system measurement offset is

determined at user level by adding an unknown to equations provided in MOPS [RD3]. When

using the 5 unknowns approach, a reference constellation shall be selected. The observation

matrix then takes the form:

, (12)




with ni = 0 if satellite is part of reference constellation and ni=1 if satellite is part of offset

constellation.

To be able to run the simulation with 5 unknowns, at least two different constellations with

ranging must be used.

4.6 Working directory and scenario folder

Working directory is the base directory for storing scenarios. Working directory is set to user

home directory by default and it can be changed clicking the Browse button in the Working

directory panel (Figure 55). Changes are saved to the registry and are loaded each time the

simulator starts.

Figure 55: Working directory.

Working directory contains the scenario directory. Scenario directory stores intermediate

and final SBAS Simulator files. It is the only directory where the tool writes data without

asking the user. It is also the base directory for saving and loading scenarios and images. The

scenario folder can be changed in the Scenario folder panel (Figure 56).

Figure 56: Scenario folder.

4.7 Scenario

Scenario is a collection of all SBAS simulator settings, including all extra user data like

constellations or RIMS. All configuration of SBAS Simulator can be saved to scenario files.

Scenarios can be managed through the Scenario panel.

Figure 57: Scenario panel.

Following buttons are present:

New - Current scenario is erased and all simulator settings return to its default state.

Settings - User can see and change all settings of the tool.

Load - Load existing scenario into the simulator.

Save – Simulator settings are saved to scenario files (*.sce).




Scenarios can be saved and loaded through scenario files. Three types of scenario files are

present:

Constellation scenario file – contains all settings related to space segment, all

constellations, satellites, almanacs, frequencies, monitoring conditions, etc.

RIMS scenario file – contains all settings related to ground segment and detailed

RIMS configuration.

Other scenario file – contains all other SBAS Simulator settings that were not covered

by constellation or RIMS scenario files.

Scenario file is a text file, where data are stored in the form of parameter=value or CSV lines.

It is divided into blocks, each starting with a #header and containing settings specific for the

block.

5 Analyses and Tools Analyses and Tools are available through buttons in the left panel of SBAS Simulator.

Description gives short information of implemented functions. After clicking any analysis or

tool button, all important configuration needed by the simulation is shown in the main panel.

Before starting the simulation, required settings shall be checked. Detailed explanation of all

possible settings in the main panel is given in section 4.

Simulation can be performed over a point or a region (see section 4.2.1). Not all simulations

are available for both and some are also restricted only to the World. Ionosphere simulation

is available only for single frequency mode. Table 8 shows the area simulation availability.

Simulation Geographical area Frequency mode

Point Region single Dual

DOP

NSE

XPL

Availability

Continuity

Ionosphere

Monitoring

XDOC

IDOC

ADOC

Coverage (World)

Elevation

Ground Tracks (World)

3D view




Sky plot Table 8: Analyses simulation availability.

For each simulation the Simulate X button is presented in the top-right corner of the main

panel. It starts the simulation or opens additional simulation settings.

Simulation intermediate and final results are saved into the simulation files. General

information about simulation files can be found in section 7. Information about specific files

is provided in the following subsections.

5.1 General computations

Several analyses share similar computations that might be performed before the actual

simulation. Those computations include satellite position, vector to satellites, SBAS

distribution, RIMS filtering, satellites monitored, etc.

Following result files can be available after the general computation is finished:

directory file description

sat SatPosition satellite positions

sat Enu vectors from users to satellites; elevation and azimuth of satellites

sat SbasDistribution SBAS distribution mask

sat Ranging satellite ranging on first and second frequency

sat SatSignals availability of satellite signals for ranging and for ionosphere

rims RimsSatPosition azimuth and elevation of satellites at RIMS

rims RimsVisible visible RIMS

rims RimsRanging RIMS types used for ranging

rims RimsMonitored number of RIMS monitored by a satellite

rims RimsCount number of RIMS types seen by a specific satellite

rims RimsSigma2 error over bound produced by each RIMS type for a specific satellite

sat SatSigma2FromRims overall error bound from used RIMS for a specific satellite

sat SatMonitor monitored satellites

sat UdreDfre σUDRE or σDFRE for specific satellite Table 9: Files generated during general computations.

Listed files are generated in a defined order that is depicted on Figure 58. Note that only files

necessary for the next simulation are generated.




Figure 58: File hierarchy for general computations.

5.2 Computations of satellite variance (σ)

The overall satellite error variance depends on the frequency mode. When the simulator is

in the single frequency mode, the total variance is computed from equation (1). In dual

frequency mode the equation (4) is used. Inputs for both equations are specified in sections

4.5.1.1 and 4.5.1.2.

Following result files are available after the satellite variance is computed:

directory File description

sat Sigma2 overall satellite variance Table 10: Files generated during the computation of satellite variance.

Before computing the satellite variance, following input files are needed:

Enu file (see Table 9)

SatSigma2FromRims file (see Table 9) – containing the σi,RIMS values

UdreDfre file (see Table 9) – input for computing σi,flt (single frequency) or σi,DFC (dual

frequency)

Sigma2Uive file (see Table 16) – input for computing σi,UIRE (only single frequency)

Figure 59 shows input files needed to compute the satellite variance. Sigma2Uive file is used

only in the single frequency mode.

Figure 59: Input files needed for the generation of the overall satellite error.




5.3 DOP

DOP computes dilution of precision, which is represented by:

HDOP

VDOP

GDOP

PDOP

TDOP

DOP Simulation just takes into account the satellite geometry. Satellite monitoring status or

frequency settings has no effect on this simulation. Availability and statistics simulation can

be computed over a point or region. Before the simulation starts, user can configure the

DOP availability limits.

Following files can be generated during the DOP simulation:


dop DopValues DOP values for all region points and times

dop DopAvailability DOP availability

dop DopStatistics DOP statistics for a region

dop DopPointStatistics DOP statistics for a point Table 11: Files generated during the DOP simulation.

Figure 60 shows the computational order of DOP files.

Figure 60: Hierarchy of DOP files.

5.3.1 Availability for a point

DOP versus time is plotted for a given point when performing availability over a point (Figure

61). Availability limit is marked by a red horizontal line. In the upper part of the graph it is

possible to see the percentage of time when the XDOP value was below its availability limit.

Use DOP buttons on the left to switch between particular results.




Figure 61: HDOP availability for point.

5.3.2 Statistics for a point

A frequency diagram is shown for a point statistics simulation (Figure 62). Availability limit is marked by a red vertical line and the percentage of time when XDOP value was below its availability limit is shown at the top of the graph.

Figure 62: HDOP statistics for a point.




5.3.3 Availability for a region

First DOP is computed for each point in the region. Then the percentage of time when DOP value was below its availability limit is calculated. Results are shown in the XDOP region availability graph (Figure 5). In the left part of user can switch between simulation results, show selected RIMS and control graph contours. More information on region graphs is provided in section 6.

5.3.4 Statistics for a region

DOP limits are not necessary and are disabled. As for availability, first DOP is computed for each point in the region. Then the average and maximum DOP values are calculated and shown in the XDOP region statistics graph (Figure 63). In the left part of the graph it is possible to do the same as in the availability graph. Users can also switch between average, maximum and percentile DOP values.

Figure 63: HDOP statistics for region.

5.4 NSE

NSE computes navigation system errors, which are represented by:

HNSE

VNSE

Only satellites that are monitored enter the NSE Simulation. The simulation also depends on the SBAS distribution provided by the augmentation satellite and on the overall sigma error bound as described in 4.5.




Following files can be generated during the NSE simulation:


nse NseValues NSE values for all region points and times

nse NseAvailability NSE availability

nse NseStatistics NSE statistics for a region

nse NsePointStatistics NSE statistics for a point

nse NsePercentile NSE 95 percentile

nse NseAvailabilityFlags NSE availability flags (0,1) based on the NSE percentile Table 12: Files generated during the NSE simulation.

The computational order of NSE files is shown on Figure 64.

Figure 64: Hierarchy of NSE files.

NSE availability and statistics can be shown for both point and region. When the simulation is run over the region user can also specify the NSE percentile which will be computed over the required area. Simulation results are shown in a similar way like the DOP results. Note that NsePercentile and NseAvailabilityFlags files are inputs for availability and continuity simulations.

5.5 XPL

XPL computes protection levels, which are represented by:

HPL

VPL Only satellites that are monitored enter the XPL Simulation. The simulation also depends on the SBAS distribution provided by the augmentation satellite and on the overall sigma error bound as described in 4.5. Following files can be generated during the XPL simulation:


xpl XplValues XPL values for all region points and times




xpl XplStatistics XPL statistics for a region

xpl XplPointStatistics XPL statistics for a point Table 13: Files generated during the XPL simulation.

Figure 65 shows the hierarchy of XPL files.

Figure 65: Hierarchy of XPL files.

XPL simulation graphs are similar to NSE statistic graphs.

5.6 Availability

Availability simulation computes the availability for a defined service level (see 4.2.3). There are several criteria to be specified for a system to be available:

1. XPL < XAL: required availability condition - this criteria is always set 2. NSE 95 percentile < NSE limit: availability in accuracy – this criteria is optional (useful

for LPV200) 3. NSE < XPL: integrity criteria – is optional

User can set availability criteria in a dialog window (Figure 66) after the Simulate Availability button is clicked.




Figure 66: Availability simulation settings.

Availability computation can be divided in the following steps:

1. Compute XPL values (XplValues file).

2. If NSE is used, compute the NSE values (NseValues file).

3. If the NSE percentile criterion is used, compute the NSE percentile (NsePercentile file)

and then the NSE availability flags (NseAvailabilityFlags file).

4. Use the XPL values and if necessary also the NSE Values and NSE availability flags and

compute the availability flags (AvailabilityFlags file).

5. Use availability flags to compute the availability (Availability file).

Following files can be generated during the availability simulation:


avail AvailabilityFlags availability flags (0,1) representing the availability at each point and time

avail Availability overall availability for a region Table 14: Files generated during the availability simulation.

The process of computing availability (continuity) is shown on Figure 67. The arrow A is used

only if the NSE percentile is taken into account. The arrow B is used only if the integrity

criterion is set.




Figure 67: Hierarchy of availability and continuity files.

Sample availability simulation for single frequency simulation is shown on Figure 68.

Figure 68: Simulated horizontal availability (24h simulation with 10 minutes time step).

5.7 Continuity

Continuity simulation computes the continuity for a defined service level (see 4.2.3). Before the continuity is computed, the system availability must be known. For that reason the same input criteria are specified as in the case of availability (see Figure 66). From the definition of continuity, the simulation makes sense only with time step of 1 second. After the availability at each moment is known, the simulator first computes the number of continuity events. It is done through a 16 seconds sliding window passing over the simulation interval and counting individual continuity events. After the number of continuity events is known, the continuity risk is computed. More details can be found in [RD6].




Following files can be generated during the continuity simulation:

directory file Description

cont Continuity continuity results Table 15: Files generated during the continuity simulation.

The process of computing continuity is shown on Figure 67.

5.8 IONO

Ionospheric simulations are available only for a region and the single frequency mode. In the

dual frequency mode, the ionosphere free solution is applied. Ionospheric simulations can

also be run only if the ionospheric model is set to IONEX or geometric GIVE model (see 4.5.4).

The following settings affect the ionosphere simulation:

Ionosphere model settings (see 4.5.4)

RIMS stations and its configuration (see 4.3)

Ionosphere check box in constellation settings (see 4.1.6)

Individual satellite settings (see 4.1.1)

Following files can be generated during ionospheric simulations:

directory File description

iono IppCoordinates IPP coordinates

iono DMonitor Dmonitor values

iono DIono Diono values, generated only for IONEX model (see 4.5.4)

iono DFactor Dfactor values, generated only for IONEX model (see 4.5.4)

iono SigmaGiveValues σGIVE for all grid points and times

iono SigmaGive σGIVE statistics

iono Sigma2Uive σUIVE for all grid points, satellites and times

iono IgpStatistics IGP statistics Table 16: Files generated during ionospheric simulations.

Figure 69 shows how ionospheric files are generated. Arrows with A are used for the IONEX

model and arrow B is used for the geometric GIVE model.




Figure 69: Hierarchy of ionospheric files.

5.8.1 IPP location

Ionospheric pierce point locations are the intersections between RIMS station and satellite

at the ionosphere height. IPPs take into the account ionospheric scintillations as defined in

4.5.4. User can select IPPs for all system, for specific satellites or RIMS.

Figure 70: IPPs around the RIMS in Berlin.

5.8.2 IGP statistics

IGP statistics monitor the situation at every IGP point. The more IPPs are around a particular IGP, the more accurate ionospheric correction this IGP will have. User can limit the maximal




distance between IPG and IPP through IGP radius in Dmonitor settings (Figure 46 and Figure 47). IGP statistics computes number of IPPs within the specified distance from every IGP. The graph (Figure 71) shows average values over the whole simulation time. Values are in the positions of IGPs. Total number of IGPs depends on using bands 9 and 10.

Figure 71: The average number of IPPs around an IGP.

5.8.3 Sigma GIVE calculation

Algorithms for computing the σGIVE depend on the ionospheric model:

IONEX ionospheric model: σGIVE is calculated using the equation (10)

Geometric GIVE model: σGIVE depends on number of IPPs around an IGP.

Configuration of the geometric GIVE model is shown on Figure 47.

This analysis provides user with the average and maximum σGIVE values during the simulation

interval. It is also possible to see the σGIVE availability computed from the given limit value.

Figure 72 shows an example of the σGIVE results.




Figure 72: σGIVE over ECAC area.

5.9 Monitoring

Satellites can be monitored by RIMS, when the parent constellation is used for ranging (see

4.1.6). A satellite is monitored, when it sees specific RIMS types as explained in 4.1.1.3. This

analysis provides user with a graphical view showing monitored satellites during the

simulation time (Figure 73). The SatMonitor file is generated as shown on Figure 58.




Figure 73: Satellites that are monitored during the 24h simulation.

5.10 DOC simulations

DOC simulation includes XDOC, IDOC and ADOC. Before starting the DOC simulation, it must

be known how many RIMS are seen from a specific satellite.

RIMS has several types: A, B, C, D, E and F. Each of the type can be active/inactive or can be

lost due to specific configuration (mask, random loss, time interval loss, etc.). Satellite is

monitored when see specific number of RIMS types as explained in 4.1.1.3.

In the XDOC, IDOC and ADOC simulation it is important to know how many RIMS are seen

from particular satellite. A RIMS is considered to be seen from a satellite, when it contributes

to the monitoring state. For example, at specific time the following RIMS with active types

are defined:

RIMS Active types

RIMS1 A,B

RIMS2 A,B

RIMS3 A,B

RIMS4 A,B

RIMS5 A,C




RIMS6 A,D

RIMS7 A,E

RIMS8 C,D,E,F

RIMS9 D,E,F Table 17: Example of RIMS and its active types.

The Satellite1 is in contact with all 9 RIMS and its types. The Satellite1 is considered

monitored, when it sees at least 5 RIMS A, and 3 RIMS B. Satellite1 is monitored, because it

sees 7 RIMS A and 4 RIMS B. But only the first 7 RIMS contribute to the monitoring state

(RIMS8 and RIMS9 have no effect on monitoring). Therefore for the XDOC, IDOC and ADOC

simulation the Satellite1 sees 7 RIMS.

Monitoring conditions on RIMS prevail and they can be turned off through a checkbox in the

DOC simulation settings window.

Following files can be generated during DOC simulations:


doc Xdoc XDOC results

doc Idoc IDOC results

doc Adoc ADOC results Table 18: Files generated during DOC simulations.

Figure 74 shows the computational order of DOC files.

Figure 74: Hierarchy of DOC files.

5.10.1 XDOC

XDOC Simulation shows the minimum number of RIMS for particular number of satellites (or

for all satellites). Before the simulation starts, the user specifies the number of satellites

(nsat).

The computation of XDOC first lists monitored satellites for a particular grid point at specific

time. Each satellite sees some RIMS. The lowest number of monitored RIMS for nsat is taken.

In the case where all satellites are used, the lowest number for all satellites is taken.




Figure 75: XDOC simulation - minimal number of RIMS for 6 satellites.

5.10.2 IDOC

IDOC Simulation shows the number of satellites monitored at least by a specific number of

RIMS. Before the simulation starts, the user specifies the number of RIMS (nRIMS).

The computation of IDOC first lists monitored satellites for a particular grid point at specific

time. Each satellite sees some RIMS. IDOC computes the number of satellites that are able to

see at least nRIMS RIMS. The simulation shows the minimal value during the simulation

interval.

5.10.3 ADOC

ADOC Simulation shows the availability and coverage time when specific number of satellites

is monitored by specific number of RIMS. Before the simulation starts, the user sets the

number of satellites (nsat) and the number of RIMS (nRIMS).

The computation of ADOC first lists monitored satellites for a particular grid point at specific

time. Each satellite sees some RIMS. The lowest number of monitored RIMS for nsat is taken.

If this lowest number is equal or higher than nRIMS, the grid point is declared as available for

ADOC at that given time. Apart from the availability, the ADOC simulation also shows the

coverage time.




5.11 Coverage, elevation, ground tracks

Coverage, elevation and ground tracks provides user with visualization related to specific

satellites.

Following files are generated during coverage, elevation and ground tracks simulations:


sat Coverage coverage results

sat SatElevation satellite elevation results

sat GroundTracks ground tracks results Table 19: Files generated during coverage, elevation and ground tracks simulations.

Figure 76 shows the dependency of coverage, elevation and ground tracks files on other

input files.

Figure 76: Hierarchy of coverage, elevation and ground tracks files.

5.11.1 Coverage

Simulation computes satellite coverage over the world. Coverage is calculated for a specific time within the simulation time interval. Results are shown on the world map (Figure 77). Each constellation is assigned with a different colour. Satellite positions are projected on the map. User can also see results only for a specific region. Coverage depends on the user mask angle.




Figure 77: Coverage simulation.

5.11.2 Elevation

Elevation is similar to the coverage simulation. The Simulate elevation button is just below

the Simulate Coverage button. User first specifies the satellite and the time, for which

elevation will be simulated.




Figure 78: Elevation simulation.

5.11.3 Ground tracks

Ground track is the path on the Earth's surface directly below the satellite. It is the projection of its orbit onto the Earth. Simulation is performed over the world (Figure 79). Constellations have different colours. Satellite ground tracks can be manually selected and deselected. User can also zoom graph to a region.




Figure 79: Ground tracks simulation showing one GPS and on Galileo satellite.

5.12 Delta map

Delta map is the difference between 2 simulations. Both simulations must be of the same type. Sources are simulation files generated before. Each simulation type supported by delta map has its own data file:

DOP region statistics (file DeltaDopStatistics.dat)

DOP region availability (file DeltaDopAvailability.dat)

NSE region statistics (file DeltaNseStatistics.dat)

NSE region availability (file DeltaNseAvailability.dat)

XPL region statistics (file DeltaXplStatistics.dat)

Region availability (file DeltaAvailability.dat)

Continuity (file DeltaContinuity.dat)

IGP statistics (file DeltaIgpStat.dat)

Sigma GIVE (file DeltaGive.dat)

XDOC (file DeltaXdoc.dat)

IDOC (file DeltaIdoc.dat)

ADOC (file DeltaAdoc.dat). Simulation files are stored in the scenario folder. Before doing delta map user should have 2 different simulation files of the same type (from 2 different scenarios). Both files must store results for the same region.




5.13 3D view

View situation tool has 2 functions: 3D View and Sky plot. 3D view shows three-dimensional Earth with satellites on their orbits. More it can provide user with simulation dynamic plots (Figure 80).

Figure 80: 3D view showing dynamic HPL and information for the selected satellite.

The view is rotated by holding the left mouse button and moving the mouse. Right button is used to move in space and mouse wheel is used for zooming. Context menu can be used if a mouse does not have a wheel. There is also the option to return to the default view. Clicking on the satellite displays its orbit. Actual data are shown in the right panel. Orbits and names of all satellites can also be seen by selecting appropriate check boxes. When dynamic graphs are used, right panel contains coloured simulation scale. At the bottom is the time control. User can scroll to a specific time or use buttons on the left to start the animation. Simulation speed says how faster the simulation goes with respect to the real time. When showing dynamic graphs, animation will be slower. On the right the time in GPS and UTC format is displayed. Camera can be set to inertial or to ECEF mode. Inertial camera shows the situation as seen from the inertial system, where satellite orbits are fixed in space. Earth is rotating during the




animation. ECEF camera is used to see always the same part of the Earth. In this mode satellite orbits will be rotating.

5.14 Sky plot

Sky plot is the second function of the view situation tool. For a point simulation, it is possible see positions of satellites on the sky during the whole simulation time (Figure 81).

Figure 81: Sky plot showing visibility of satellites from Paris.

Check boxes in the left panel are used to show or hide satellite names or trajectories. The red circle marks the user mask angle. At the bottom is the animation panel with the same functions as in 3D view. Sky plot can also show actual positions of existing GPS satellites. First the coordinates must be set to user location. Then current GPS almanac shall be loaded (simulation start time is automatically changed to the current time). After running the simulation, actual satellite positions can be seen from the user area.

6 Graphs There are many different types of graphs that can be viewed in the SBAS Simulator. Some of

the graph types are described in other sections of this manual: Both types of Point graph are

described in 5.3.1 and 5.3.2, Coverage graph is described in 5.11.1, Ground tracks graph is




described in 5.11.3, 3D view is described in 5.13, Sky plot is described in 5.14 and the

Monitoring graph is described in 5.9.

6.1 Region graph

The Region graph shows a specified region of the world map (or the whole world map) with

desired data overlapping the world map’s region. An example of a Region graph can be seen

in Figure 63. The graph’s window has many controls that modify the way the graph is

displayed on the screen.

It is also possible to export the graph into a file: The Export graph button in the lower right

corner serves for this purpose. Before the graph is saved to a file, the pixel resolution of the

image has to be chosen. User shall also specify the path to the file and the file format (bmp,

jpg, wbmp, png and gif).

6.1.1 Region graph controls

Apart from buttons on the right side of the window, which are used to zoom in, zoom out

and also move the graph when the view is zoomed in, there are several controls on the left

side of the window (see Figure 82).

Figure 82: Example of controls on the left side of the Region graph window.




Show Z values checkbox is used to enable and disable the printing of z values inside the

graph area. Show RIMS checkbox is used to enable or disable the printing of RIMS in the

graph area.

The Levels button is used to modify the number of levels and also the maximum and

minimum of the range of these levels. For example: In Figure 82 the number of levels is set

to 10 (represented by 10 different colours in the bar above the Levels button), minimum is

set to 0.69 and maximum to 1.04 (both of these values are also seen in the bar above the

Levels button).

The Reverse colours button reverses the order of colours shown in the bar (see Figure 82).

For example: In Figure 82 the colours go from blue to red as the values grow, reversing the

colours would cause the colours to go from red to blue as the values grow.

The Service area layers dropdown menu is used to select which region is to be highlighted in

the graph area. Apart from regions specified in section 4.2.1, the satellite map can also be

shown.

If Draw break line is selected, a black line is drawn in the graph area, separating lower and

higher values by the specified break value. Alternative way to display such division into two

disjoint subsets is to select Use only 2 colours: Instead of a black line the graph is coloured

only using two colours, red (or blue if the Use blue as max is checked) areas contain values

greater than the break and white areas contain values less than the break.

7 SBAS Simulator Files

7.1 Simulation steps

Each simulation can be divided into simulation steps which are subtasks of the main process. They are simple simulations with defined input and output. For example to perform DOP simulation the simulator goes through the following steps (see also Figure 58 and Figure 60):

1. Compute satellite positions for all used satellites within the simulation interval (SatPosition file).

2. Use satellite positions and calculate ENU coordinates for user location (Enu file). 3. Use computed ENU coordinates and calculate DOP (DopValues file).

The advantage of separating simulations into steps is the reusability of already computed tasks. Simulation results are saved to simulation files. The last simulation file contains data which are plotted in the graph. Files are saved to the scenario directory. Writing and reading permissions are needed for the scenario directory otherwise it is not possible to run the tool.

7.2 Data and meta-files

Simulation file is actually a set of two files. Both have the same names, but different extensions. Results are stored in data file (*.dat). It is a CSV file with a defined number of




columns which are separated by semicolons. Meta file (*.meta) contains various simulator settings that were used when generating data file. Data are stored in the form of parameter-value or CSV lines. First three rows of meta file are:

FILE ID - hash code computed from simulation step input

CRC - cyclic redundancy check of associated data file

COLUMNS – columns in data file.

Input is unambiguously defined for each simulation step. For the same input, each set of files is generated only once. This feature speeds up the simulation process, because some computations can be omitted. COLUMNS specify names of columns in data file. For example TI is the time index looping all simulation times, SI is the satellite index looping all used satellites, RI is the RIMS index of used RIMS. The meaning of other columns should be clear. Before each simulation step following check is done:

1. If data or meta file do not exist, perform the simulation and generate files, otherwise go to 2.

2. If FILE ID is not the same as the input hash code, perform the simulation and generate files, otherwise go to 3.

3. If CRC specified in meta file is not the same as CRC computed from data file, perform the simulation and generate files, otherwise skip this simulation step.

Simulation files are stored in directories under the scenario directory. Directories group similar simulation files. The list of simulation files can be found in tables in section 5.




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