Page 1
GSG-5/6 Series GNSS Simulator
User Reference Guide
with SCPI Guide
Spectracom Part No.: 4031-600-54001
Revision: 22
Date: 10-Sept-2015
spectracom.com
www.nav-cn.com
Page 2
Page 3
© 2012-15 Spectracom, Inc. All rights reserved.
The information in this document has been carefully reviewed and is believed
to be accurate and up-to-date. This User Guide is subject to change without
notice. For the most current version of this documentation, please see our
web site at spectracom.com.
Spectracom reserves the right to make changes to the product described in
this document at any time and without notice. Any software that may be
provided with the product described in this document is furnished under a
license agreement or nondisclosure agreement. The software may be used or
copied only in accordance with the terms of those agreements.
No part of this publication may be reproduced, stored in a retrieval system, or
transmitted in any form or any means electronic or mechanical, including
photocopying and recording for any purpose other than the purchaser's
personal use without the written permission of Spectracom, Inc.
Other products and companies referred to herein are trademarks or registered
trademarks of their respective companies or mark holders.
Spectracom Corp.
• 1565 Jefferson Road, Suite 460, Rochester, NY 14623U SA
• Room 208 , No. 3 ZhongGuan Village South Road, Hai Dian Di strict, Beijing100081, China
• 3, Avenue du Canada, 91974 Les Ulis Cedex,France
Questions or comments regarding this User Guide?
è E-mail: techpubs@spectracom.orolia.com
User Guide GSG-5/6 Series I
Page 4
SPECTRACOM LIMITED WARRANTY
Five Year Limited Warranty
Spectracom, a business of the Orolia
Group, warrants each new standard
product to be free from defects in material,
and workmanship for five years after
shipment in most countries where these
products are sold, EXCEPT AS NOTED
BELOW (the “Warranty Period” and
"Country Variances").
Warranty Exceptions
This warranty shall not apply if the product
is used contrary to the instructions in its
manual or is otherwise subjected to
misuse, abnormal operations, accident,
lightning or transient surge, or repairs or
modifications not performed by
Spectracom authorized personnel.
Items with a variance to the Five Year
Warranty Period are as follows:
90 Days Warranty
TimeKeeper Software
One Year Limited Warranty
Timeview Analog Clock
Path Align-R Products
Bus-level Timing Boards
IRIG-B Distribution Amplifiers
Two Year Limited Warranty
Rubidium Oscillators
Epsilon Board EBO3
Epsilon Clock 1S, 2S/2T, 3S, 31M
Epsilon SSU
Power Adaptors
Digital and IP/POE Clocks
WiSync Wireless Clock Systems and
IPSync IP Clocks
Rapco 1804, 2804, 186x, 187x, 188x,
189x, 2016, 900 series
Three Year Limited Warranty
Pendulum Test & Measurement Products
GPS- 12R, CNT- 9x, 6688/6689, GPS88/89, DA-35/36, GPS/GNSS Simulators
Country Variances
All Spectracom products sold in India have
a one year warranty.
Warranty Exclusions
Batteries, fuses, or other material
contained in a product normally consumed
in operation.
Shipping and handling, labor & service
fees EXCEPT FOR THE LIMITED
WARRANTY STATED ABOVE,
SPECTRACOM DISCLAIMS ALL
WARRANTIES OF ANY KIND WITH
REGARD TO SPECTRACOM PRODUCTS
OR OTHER MATERIALS PROVIDED BY
SPECTRACOM, INCLUDING WITHOUT
LIMITATION ANY IMPLIED WARRANTY
OR MERCHANTABILITY OR FITNESS
FOR A PARTICULAR PURPOSE.
Spectracom shall have no liability or
responsibility to the original customer or
any other party with respect to any liability,
loss, or damage caused directly or
indirectly by an Spectracom product,
material, or software sold or provided by
Spectracom, replacement parts or units, or
services provided, including but not limited
to any interruption of service, excess
charges resulting from malfunctions of
II User Guide GSG-5/6 Series
Page 5
hardware or software, loss of business
or anticipatory profits resulting from
the use or operation of the
Spectracom product or software,
whatsoever or howsoever caused. In
no event shall Spectracom be liable
for any direct, indirect, special or
consequential damages whether the
claims are grounded in contract, tort
(including negligence), or strict
liability.
Extended Warranty
Coverage
Extended warranties can be
purchased for additional periods
beyond the standard warranty.
Contact Spectracom no later than the
last year of the standard warranty for
extended coverage.
Warranty Claims
Spectracom’s obligation under this
warranty is limited to the cost of infactory repair or replacement, at
Spectracom’s option, of the defective
product or the product’s defective
component. Spectracom’s Warranty
does not cover any costs for
installation, reinstallation, removal or
shipping and handling costs of any
warranted product. If in Spectracom’s
sole judgment, the defect is not
covered by the Spectracom Limited
Warranty, unless notified to the
contrary in advance by customer,
Spectracom will make the repairs or
replace components and charge its
then current price, which the customer
agrees to pay.
In all cases, the customer is
responsible for all shipping and
handling expenses in returning
product to Spectracom for repair or
evaluation. Spectracom will pay for
standard return shipment via common
carrier. Expediting or special delivery
fees will be the responsibility of the
customer.
Warranty Procedure
Spectracom highly recommends that
prior to returning equipment for
service work, our technical support
department be contacted to provide
troubleshooting assistance while the
equipment is still installed. If
equipment is returned without first
contacting the support department and
“no problems are found” during the
repair work, an evaluation fee may be
charged.
Spectracom shall not have any
warranty obligations if the procedure
for warranty claims is not followed.
Customer must notify Spectracom of a
claim, with complete information
regarding the claimed defect. A Return
Authorization (RMA) Number issued
by Spectracom is required for all
returns.
Returned products must be returned
with a description of the claimed
defect, the RMA number, and the
name and contact information of the
individual to be contacted if additional
information is required by Spectracom.
Products being returned on an RMA
must be properly packaged with
transportation charges prepaid.
User Guide GSG-5/6 Series III
Page 6
IV User Guide GSG-5/6 Series
Page 7
SPECTRACOM LIMITED WARRANTY
CHAPTER 1
II
Introduction
1.1 Quick Start Guide
1.2 Welcome
1.2.1 Key Features 3
1.2.2 Typical Applications 4
1.2.3 Intended Use and Operating Principle 4
1.2.4 Compliance & Legal Notices 5
1.2.4.1 About this Document
1.2.4.2 Declaration of Conformity
1.2.5 Technical Specifications 6
1.2.5.1 RF Output Specifications
1.2.5.2 Rear Outputs and Inputs
1.2.5.3 Time Base
1.2.5.4 Optional Antenna
1.2.5.5 Environmental
CHAPTER 2
Setup
2.1 About Your Safety
2.1.1 Safety Precautions 12
2.1.2 Basic User Responsibilities 12
2.1.3 If in Doubt about Safety 13
1
2
3
6
6
6
7
8
8
9
11
12
CONTENTS
User Guide GSG-5/6 Series • TABLE OF CONTENTS
2.2 Unpacking and Inventory
2.2.1 Unit Identification 14
2.3 MechanicalInstallation
2.3.1 General Installation Considerations 14
2.4 Electrical Installation
2.5 Signal Power Level Considerations
2.5.1 Compliance: Using an Antenna 22
13
14
21
22
V
Page 8
2.5.2 Transmit Power Level 23
CHAPTER 3
Features & Functions
3.1 Front Panel
3.1.1 Description of Keys 28
3.1.1.1 Power
3.1.1.2 Start
3.1.1.3 Exit
3.1.1.4 Cancel
3.1.1.5 Menu
3.1.1.6 View
3.1.1.7 Enter
3.1.1.8 Arrows
3.1.1.9 N/S
3.1.1.10 E/W
3.1.1.11 Numeric Keys
3.1.1.12 +/– (format)
3.1.1.13 [.] (hold)
3.2 Rear Panel
3.3 The GSG Main Menu
3.4 "Start" Menu
3.4.1 Scenario Start Variations 33
3.4.2 Scenario Execution Views 33
3.4.2.1 View 1/x
3.4.2.2 View >1/x
3.4.2.3 Last View
25
27
28
28
28
28
28
29
29
29
29
29
29
29
30
30
31
32
34
34
37
VI
3.5 "Select" Menu
3.5.1 Start Time 39
3.5.2 Duration 40
3.5.3 Latitude, Longitude, Altitude 41
3.5.4 Trajectory 41
3.5.4.1 Predefined Trajectories
3.5.4.2 Trajectory Files
3.5.4.3 Timestamp Usage in Trajectories
3.5.5 Ephemeris 45
3.5.5.1 Default Ephemeris
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42
43
44
45
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3.5.5.2 Download Ephemeris
3.5.5.3 User-Uploaded Ephemeris
46
46
3.5.6 Leap Second 49
3.5.7 Event Data 50
3.5.8 Antenna Settings 55
3.5.8.1 Antenna model
3.5.8.2 Lever arm
3.5.8.3 Elevation mask
55
56
56
3.5.9 Advanced Configuration Options 57
3.5.9.1 Multipath signals
3.5.9.2 Interference signals
3.5.9.3 Base station
3.5.9.4 Environment models
3.5.9.5 Atmospheric model
57
59
62
63
66
3.5.10 Satellite Configuration 68
3.5.10.1 Satellite Systems
3.5.10.2 Number of Satellites
3.5.10.3 Frequency Bands and Signal De-/Activation
3.5.10.4 Satellite Constellations
3.5.10.5 Encryption
3.5.10.6 SBAS Satellites
69
69
70
72
74
75
3.6 "Options" Menu
3.6.1 Transmit Power 78
3.6.1.1 External Attenuation
3.6.1.2 Noise Generation
3.6.2 Signal Generator 83
3.6.2.1 Signal type
3.6.2.2 Satellite ID
3.6.2.3 Transmit power
3.6.2.4 Frequency offset
3.6.2.5 Start time
3.6.2.6 Ephemeris
3.6.2.7 AutoStart
3.6.3 Interface and Reference 87
3.6.3.1 Network Configuration
3.6.3.2 Proxy Configuration
3.6.4 Manage Files 90
3.6.5 Show System Information 92
78
80
81
84
85
85
86
86
86
86
88
89
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3.6.6 Restore Factory Defaults 92
3.6.7 Calibration 93
CHAPTER 4
Frequent Tasks
4.1 Working with Scenarios
4.1.1 Scenario Start/Stop/Hold/Arm 96
4.1.2 Running a Scenario 96
4.1.3 Holding a Scenario 97
4.1.4 Configuring a Scenario 97
4.2 Locking/Unlocking the Keyboard
4.3 Adjusting Transmit Power
4.4 Accessing the GSG Web UI
4.5 Using the CLI
4.6 Performing a Receiver Cold Start
4.7 Updating Firmware
4.8 Uploading Files using StudioView
4.8.1 StudioView Uploader 104
4.9 Leap Second Configuration
CHAPTER 5
95
96
100
101
101
103
103
104
104
107
VIII
Reference
5.1 The GSG Web UI
5.2 Messages
5.3 Timing Calibration
5.4 NMEA Logging
5.5 Execution Log
5.6 Saving RINEX Data
5.7 YUMA Almanac File
5.8 Default Settings
5.9 Pre-Installed Scenarios
5.10 Default Scenario Satellites
5.10.1 GLONASS Default Satellite Types 122
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109
110
110
115
116
117
117
118
119
119
121
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5.11 Scenario File Format
123
5.12 GSG StudioView Software
5.13 GSG Series Model Variants and Options
5.13.1 Which GSG Model & Options Do I Have? 136
5.13.2 GSG Models & Variants 137
5.13.2.1 GSG-51 Series
5.13.2.2 GSG-5 Series
5.13.2.3 GSG-6 Series
5.13.3 List of Available Options 138
5.14 Problems?
5.14.1 Technical Support 139
5.14.1.1 Regional Contact
5.15 License Notices
CHAPTER 6
SCPI Guide
6.1 SCPI Guide: Introduction
6.2 Protocol
6.2.1 General Format of Commands 158
6.2.2 Protocol Errors 159
135
136
137
137
138
139
139
140
153
158
158
6.3 Command Reference
161
6.3.1 Common Commands 161
6.3.1.1 *CLS
6.3.1.2 *ESE
6.3.1.3 *ESR?
6.3.1.4 *IDN?
6.3.1.5 *OPC
6.3.1.6 *OPC?
6.3.1.7 *RST
6.3.1.8 *SRE
6.3.1.9 *SRE?
6.3.1.10 *STB?
6.3.1.11 *TST?
6.3.1.12 *WAI
161
161
162
162
163
164
165
165
166
166
167
167
6.3.2 SYSTem: Subsystem Commands 168
6.3.2.1 SYSTem:ERRor?
168
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6.3.2.2 SYSTem:RESET:FACTory
169
6.3.3 SOURce: Subsystem Commands 169
6.3.3.1 SOURce:POWer
6.3.3.2 SOURce:POWer?
6.3.3.3 SOURce:EXTREF
6.3.3.4 SOURce:EXTREF?
6.3.3.5 SOURce:PPSOUTput
6.3.3.6 SOURce:PPSOUTput?
6.3.3.7 SOURce:EXTATT
6.3.3.8 SOURce:EXTATT?
6.3.3.9 SOURce:NOISE:CONTRol
6.3.3.10 SOURce:NOISE:CONTRol?
6.3.3.11 SOURce:NOISE:CNO
6.3.3.12 SOURce:NOISE:CNO?
6.3.3.13 SOURce:NOISE:BW
6.3.3.14 SOURce:NOISE:BW?
6.3.3.15 SOURce:NOISE:OFFSET
6.3.3.16 SOURce:NOISE:OFFSET?
6.3.3.17 SOURce:ONECHN:CONTrol
6.3.3.18 SOURce:ONECHN:CONTrol?
6.3.3.19 SOURce:ONECHN:SATid
6.3.3.20 SOURce:ONECHN:SATid?
6.3.3.21 SOURce:ONECHN:STARTtime
6.3.3.22 SOURce:ONECHN:STARTtime?
6.3.3.23 SOURce:ONECHN:EPHemeris
6.3.3.24 SOURce:ONECHN:EPHemeris?
6.3.3.25 SOURce:ONECHN:FREQuency
6.3.3.26 SOURce:ONECHN:FREQuency?
6.3.3.27 SOURce:ONECHN:SIGNALtype
6.3.3.28 SOURce:ONECHN:SIGNALtype?
6.3.3.29 SOURce:SCENario:LOAD
6.3.3.30 SOURce:SCENario:LOAD?
6.3.3.31 SOURce:SCENario:CONTrol
6.3.3.32 SOURce:SCENario:CONTrol?
6.3.3.33 SOURce:SCENario:PROPenv
6.3.3.34 SOURce:SCENario:PROPenv?
6.3.3.35 SOURce:SCENario:LOG?
6.3.3.36 SOURce:SCENario:OBServation
6.3.3.37 SOURce:SCENario:OBServation?
6.3.3.38 SOURce:SCENario:NAV
170
170
171
171
171
172
172
173
173
174
174
175
175
175
176
176
177
177
178
179
180
181
181
181
182
182
183
183
184
184
185
185
186
187
187
188
189
189
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6.3.3.39 SOURce:SCENario:NAV?
6.3.3.40 SOURce:SCENario:SATid[n]?
6.3.3.41 SOURce:SCENario:SIGNALtype[n]?
6.3.3.42 SOURce:SCENario:SIGNALtype?
6.3.3.43 SOURce:SCENario:NAVBITS
6.3.3.44 SOURce:SCENario:FREQuency[n]?
6.3.3.45 SOURce:SCENario:FREQuency?
6.3.3.46 SOURce:SCENario:POWer[n]
6.3.3.47 SOURce:SCENario:POWer[n]?
6.3.3.48 SOURce:SCENario:POWer
6.3.3.49 SOURce:SCENario:POWer?
6.3.3.50 SOURce:SCENario:FREQBAND:POWer
6.3.3.51 SOURce:SCENario:SVmodel[n]?
6.3.3.52 SOURce:SCENario:SVmodel?
6.3.3.53 SOURce:SCENario:LIST?
6.3.3.54 SOURce:SCENario:ANTennamodel
6.3.3.55 SOURce:SCENario:ANTennamodel?
6.3.3.56 SOURce:SCENario:TROPOmodel
6.3.3.57 SOURce:SCENario:TROPOmodel?
6.3.3.58 SOURce:SCENario:IONOmodel
6.3.3.59 SOURce:SCENario:IONOmodel?
6.3.3.60 SOURce:SCENario:KEEPALTitude
6.3.3.61 SOURce:SCENario: KEEPALTitude?
6.3.3.62 SOURce:SCENario:POSition
6.3.3.63 SOURce:SCENario:POSition?
6.3.3.64 SOURce:SCENario:ECEFPOSition
6.3.3.65 SOURce:SCENario:ECEFPOSition?
6.3.3.66 SOURce:SCENario:DATEtime
6.3.3.67 SOURce:SCENario:DATEtime?
6.3.3.68 SOURce:SCENario:RTCM?
6.3.3.69 SOURce:SCENario:RTCMCFG?
6.3.3.70 SOURce:SCENario:RTCMCFG
6.3.3.71 SOURce:SCENario:DUPlicate
6.3.3.72 SOURce:SCENario:DUPlicate[n]
6.3.3.73 SOURce:SCENario:DUPlicate?
6.3.3.74 SOURce:SCENario:MULtipath[n]
6.3.3.75 SOURce:SCENario:MULtipath[n]?
6.3.3.76 SOURce:SCENario:DELete[n]
6.3.3.77 SOURce:SCENario:DELete
6.3.3.78 SOURce:SCENario:DELete[n]
190
190
191
192
192
195
195
196
196
197
198
199
199
200
201
201
201
202
202
202
203
203
204
204
205
205
206
207
207
208
208
209
209
210
211
212
213
214
215
215
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6.3.3.79 SOURce:FILe:TYPe
6.3.3.80 SOURce:FILe:NAMe
6.3.3.81 SOURce:FILe:LENgth
6.3.3.82 SOURce:FILe:CHECKsum
6.3.3.83 SOURce:FILe:DATA
6.3.3.84 SOURce:KEYLOCK:PASSWord
6.3.3.85 SOURce:KEYLOCK:PASSWord?
6.3.3.86 SOURce:KEYLOCK:STATus
6.3.3.87 SOURce:KEYLOCK:STATus?
216
216
217
217
218
219
219
220
220
6.3.4 Mass Memory Subsystem Commands 220
6.3.4.1 MMEMory:CATalog?
6.3.4.2 MMEMory:CDIRectory
6.3.4.3 MMEMory:CDIRectory?
6.3.4.4 MMEMory:DATA?
6.3.4.5 MMEMory:DELete
6.3.4.6 MMEMory:COPY
6.3.4.7 MMEMory:MOVE
221
221
222
222
223
223
223
6.3.5 Network Subsystem Commands 224
6.3.5.1 NETwork:MACaddress?
224
6.3.6 STATus: Subsystem Commands 224
6.3.6.1 STATus:OPERation:CONDition?
6.3.6.2 STATus:OPERation:ENABle
6.3.6.3 STATus:OPERation[:event]?
6.3.6.4 STATus:QUEStionable:CONDition?
6.3.6.5 STATus:QUEStionable:ENABle
6.3.6.6 STATus:QUEStionable[:EVENt]?
6.3.6.7 STATus:PRESet
224
225
226
226
226
227
227
XII
6.4 Sensors Command Reference
228
6.4.1 Supported Sensor Types 229
6.4.1.1 Accelerometer
6.4.1.2 Linear Accelerometer
6.4.1.3 Gravimeter
6.4.1.4 Gyroscope
6.4.1.5 Odometer
6.4.1.6 Odometer 3D
229
229
230
230
230
230
6.4.2 Sensor Commands 230
6.4.2.1 SOURce:SENSor:REGister
6.4.2.2 SOURce:SENSor:REGister?
6.4.2.3 SOURce:SENSor:UNREGister
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230
231
231
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6.4.2.4 SOURce:SENSor:DATa?
6.4.2.5 SOURce:SENSor:NORMalize SENSOR_TYPE
6.4.2.6 SOURce:SENSor:NORMalize? SENSOR_TYPE
6.4.2.7 SOURce:SENSor:MAXrange SENSOR_TYPE
6.4.2.8 SOURce:SENSor:MAXrange? SENSOR_TYPE
231
231
232
232
232
6.5 RSG Command Reference
232
6.5.1 Data Types 232
6.5.2 TIME Parameter 233
6.5.3 RSG Commands 234
6.5.3.1 SOURce:SCENario:POSition TIME
6.5.3.2 SOURce:SCENario:POSition?
6.5.3.3 SOURce:SCENario:ECEFPOSition TIME
6.5.3.4 SOURce:SCENario:ECEFPOSition?
6.5.3.5 SOURce:SCENario:SPEed TIME
6.5.3.6 SOURce:SCENario:SPEed?
6.5.3.7 SOURce:SCENario:HEADing TIME
6.5.3.8 SOURce:SCENario:HEADing?
6.5.3.9 SOURce:SCENario:RATEHEading TIME
6.5.3.10 SOURce:SCENario:RATEHEading?
6.5.3.11 SOURce:SCENario:TURNRATE TIME
6.5.3.12 SOURce:SCENario:TURNRATE?
6.5.3.13 SOURce:SCENario:TURNRADIUS TIME
6.5.3.14 SOURce:SCENario:TURNRADIUS?
6.5.3.15 SOURce:SCENario:VELocity TIME
6.5.3.16 SOURce:SCENario:VELocity?
6.5.3.17 SOURce:SCENario:VSPEed TIME
6.5.3.18 SOURce:SCENario:VSPEed?
6.5.3.19 SOURce:SCENario:ENUVELocity TIME
6.5.3.20 SOURce:SCENario:ENUVELocity?
6.5.3.21 SOURce:SCENario:ECEFVELocity
6.5.3.22 SOURce:SCENario:ECEFVELocity?
6.5.3.23 SOURce:SCENario:ACCeleration TIME
6.5.3.24 SOURce:SCENario:ACCeleration?
6.5.3.25 SOURce:SCENario:VACCel TIME
6.5.3.26 SOURce:SCENario:VACCel?
6.5.3.27 SOURce:SCENario:ENUACCel TIME
6.5.3.28 SOURce:SCENario:ENUACCel?
6.5.3.29 SOURce:SCENario:ECEFACCel TIME
6.5.3.30 SOURce:SCENario:ECEFACCel?
234
234
235
236
236
237
237
237
238
238
239
239
239
240
240
241
241
242
242
243
243
244
244
244
245
245
246
246
247
247
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6.5.3.31 SOURce:SCENario:PRYattitude TIME
6.5.3.32 SOURce:SCENario:PRYattitude?
6.5.3.33 SOURce:SCENario:DPRYattitude TIME
6.5.3.34 SOURce:SCENario:DPRYattitude?
6.5.3.35 SOURce:SCENario:PRYRate TIME
6.5.3.36 SOURce:SCENario:PRYRate?
6.5.3.37 SOURce:SCENario:DPRYRate TIME
6.5.3.38 SOURce:SCENario:DPRYRate?
6.5.3.39 SOURce:SCENario:KEPLER TIME
6.5.3.40 SOURce:SCENario:KEPLER?
6.5.3.41 SOURce:SCENario:RUNtime?
6.5.3.42 SOURce:SCENario:DATEtime?
6.5.3.43 SOURce:SCENario:ELAPsedtime?
6.5.3.44 SOURce:SCENario:RSGUNDERflow
6.5.3.45 SOURce:SCENario:RSGUNDERflow?
6.5.3.46 SOURce:SCENario:DOPPler?
6.5.3.47 SOURce:SCENario:PRANge?
6.5.3.48 SOURce:SCENario:CHINview?
6.5.3.49 SOURce:SCENario:SVINview?
6.5.3.50 SOURce:SCENario:SVPos[n]?
6.5.3.51 SOURce:SCENario:SVPos[n]?
247
248
248
249
249
250
250
251
251
252
252
253
253
254
255
255
256
257
258
258
259
6.6 RSG Programming
6.6.1 Usage Recommendations 260
6.6.1.1 Communication Interface
6.6.1.2 Synchronization
6.6.1.3 Underflow and Overflow
6.6.1.4 Best Practices
6.6.1.5 Limitations
6.6.2 Trajectory FILE Format 261
6.7 Revision History, SCPI Guide
APPENDIX
Appendix
7.1 Lists of Tables and Images
7.2 GSG User Manual Revision History
INDEX
260
260
260
261
261
261
262
i
ii
iii
XIV
User Guide GSG-5/6 Series • TABLE OF CONTENTS
Page 17
Introduction
This first Chapter not only provides an overview of GNSS simulation
and the Spectracom GSG Series Simulators, but also information
relevant to your personal safety, as well as technical specifications.
The following topics are included in this Chapter:
1.1 Quick Start Guide 2
1.2 Welcome 3
1.2.1 Key Features 3
1.2.2 Typical Applications 4
1.2.3 Intended Use and Operating Principle 4
1.2.4 Compliance & Legal Notices 5
1.2.4.1 About this Document 6
1.2.4.2 Declaration of Conformity 6
1.2.5 Technical Specifications 6
1.2.5.1 RF Output Specifications 6
1.2.5.2 Rear Outputs and Inputs 7
1.2.5.3 Time Base 8
1.2.5.4 Optional Antenna 8
1.2.5.5 Environmental 9
CHAPTER 1
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1.1 Quick Start Guide
1.1 Quick Start Guide
The following procedure is a brief outline on how to get started with your GSG-5/6 unit.
The minimal setup steps are:
1.
Unpack the unit (see "Unpacking and Inventory" on page 13), and place it on a desktop or
install it in a rack, as described under "Mechanical Installation" on page 14.
2.
Connect the receiver antenna cable to the RF Out connector on the front panel. (See also
"Electrical Installation" on page 21.)
3.
Connect the power cable to a wall socket. Press the ON/OFF key to start the unit.
4.
The GSG display will show the Start view: Verify that the right-hand side shows an
overview of a test scenario (name, date, lat/long/traj, etc.).
5.
If no scenario is shown, use the arrow and enter keys to select Select from the main menu.
This will open up a list of pre-defined scenarios. Select one of the scenarios from this list.
6.
Press the start key to begin with the scenario execution.
7.
Start the GNSS receiver you want to test.
Note: It may be necessary to clear the memory of your GNSS receiver, i.e.
erase old data. This is typically referred to as a Cold Start , where any
ephemeris data and almanac data are removed from the receiver’s memory.
8.
Your GNSS receiver under test should see and track the generated signals. If the receiver
could successfully decode the navigation data included in the signals (this process often
takes approximately 40 seconds), the receiver will output the navigation fix as specified in
the selected scenario. This navigation solution should correspond to the solution shown on
the GSG-5/6 display.
2
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1.2 Welcome
1.2 Welcome
The GSG-5™ and GSG-6™ Series of GNSS Constellation Simulators provide a wide-range of
capabilities for in-line production testing and development testing, including navigational fix and
position testing, while offering ease-of-operation.
GSG-51 is a single-channel GPS L1 RF generator, capable of emulating a single GNSS signal.
One of the main applications for these cost-effective units is fast manufacturing testing of GPS
receivers.
GSG- 5 Series simulators reproduce the environment of a GNSS receiver. Depending on the
configuration, these units simulate up to sixteen GNSS satellites, up to 3SBAS satellites,
together with optional multipath and interference signals. The GSG-5 Series applies models to
simulate satellite motions, atmospheric effects, and different antenna types. The movement of the
GNSS receiver under test is defined using NMEA data or pre-defined trajectory models.
GSG-6Series simulators add advanced features and the capability to simulate up to 64 satellites
(configuration-dependent) on different frequency bands simulatenously. New signal types include
GPS L2P, L2C and L5, GLONASS L2, Galileo E1 and E5a/b, BeiDou B1 and B2, and QZSS L1
C/A, L2C, L5 and L1 SAIF, IRNSS L5.
1.2.1 Key Features
Since GNSS testing requirements may vary considerably from application to application,
GSGSeries simulators are available in a multitude of configurations (see "GSG Series Model
Variants and Options" on page 136).
Some of the key features are:
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1.2 Welcome
Up to 64 independent satellite channels can be simulated.
Supported signal types:
GPS L1, L2, C/A and P-Code; L2C and L5
GLONASS L1, L2, C/A and P-Code
Galileo E1/E2 and E5
BeiDou compatible
Support of different types of SBAS simulation: EGNOS, WAAS, MSAS, GAGAN
Generation of white noise, multipath and interference signals
Receiver sensitivity testing with accurate, variable output levels ranging from –65 to –160
dBm
High accuracy time base
GSG Series simulators offer a front panel display with an intuitive software User Interface, allow
for remote Web-based operation, and include GSG StudioView™, a PC-based software with
Google Maps™ interface to create custom scenarios.
1.2.2 Typical Applications
Basic Receiver Testing
Time-to-First-Fix (TTFF): How fast the GNSS receiver can get a position fix after a cold
start
Reacquisition Time: How fast the GNSS receiver can get a fix after a hot or warm start
Location: Test different locations in the world, position accuracy
Sensitivity: Acquisition and Tracking Sensitivity
Noise Susceptibility: SNR limit testing
Advanced Receiver Testing
Trajectories: Test receiver while moving
1PPS: Verify the receiver timing accuracy
Leap Second: Test the leap second handling of the receiver
Multipath: Perform basic receiver tests under multipath conditions
1.2.3 Intended Use and Operating Principle
Spectracom GSG-Series Signal Generators and GNSS Simulators are used to test GNSS
receivers by generating GNSS signals, as they are transmitted by GNSS satellites. The signals
are transmitted via air (using an antenna; see "Signal Power Level Considerations" on page 22), or
via an RF cable.
4
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1.2 Welcome
Depending on the model, and the options installed in a GSG unit, generated/simulated signals, as
well as user position, time and output power can be manipulated by the user either:
during the test, i.e. in real-time, via the GSG front panel, or
before beginning the test, by saving the programmed signal data (as well as trajectory data,
if the receiver is to be tested under virtual movement conditions) in scenario files, using the
optional StudioView™ software.
In addition to GNSS, other signals such as interference and multi-path can be generated to test the
sensitivity to various disruptions.
The number of channels installed in a GSG unit determines how many signals can be generated. If
more channels are required than available, two or more GSG units can be synchronized to
generate 128, 256, or more signals.
Built-in trajectories (static, configurable circle, and rectangular as defined in 3GPP TS 25.171) or
user-designed trajectories (in NMEA standard format) can be run on GSG simulators. Users can
upload their own ephemeris data in standard RINEX format or re-use the default data for any time
periods. The GSG-6 Series is capable of automatically downloading historical RINEX, WAAS and
EGNOS data from official websites, as needed.
The GSG-6 Series can be controlled via an Ethernet network connection, or USB or GPIB. A builtin web interface allows remote operation of the instrument. With the optional GSG StudioView™
PC Software, you can build, edit, and manage the most complex scenarios, including building
trajectories via Google Maps, independent of the GSG unit, for later upload.
Besides the variety of built-in navigation/positioning tests, GSG units are also suited for accurate
testing of timing GNSS-receivers. The GSG-6 is equipped with an ultra-high-stability OCXO
timebase for precision timing of the satellite data, or use external synchronization from a 10 MHz
reference from e.g. a Cesium or Rubidium clock. A built-in 1PPS output, synchronized to the
generated satellite data, allows comparison with the 1PPS signal from the timing receiver under
test.
1.2.4 Compliance & Legal Notices
Spectracom’s GSG-Series GNSS Simulator products meet all FCC and CE Mark regulations for
operation as electronic test equipment.
Note: For more information about Signal Power Emissions, see "Signal Power Level
Considerations" on page 22.
Note: For more information about Software Licensing, see "License Notices" on
page 140.
In particular, this instrument has been designed and tested for Measurement CategoryI, Pollution
Degree2, in accordance with EN/IEC61010- 1:2001 and CAN/CSA- C22.2 No.61010- 1- 04
(including approval). It has been supplied in a safe condition.
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1.2 Welcome
1.2.4.1 About this Document
This GSG-5/6 Series User Manual contains directions and reference information for use that
applies to the GSG-5/6 Series products.
Study this manual thoroughly to acquire adequate knowledge of the instrument, especially the
section on Safety Precautions hereafter and the Installation section.
1.2.4.2 Declaration of Conformity
A copy of the Declaration of Conformity is shipped with your unit. The complete text with formal
statements concerning product identification, manufacturer and standards used for type testing is
available on request.
1.2.5 Technical Specifications
1.2.5.1 RF Output Specifications
RF Constellation Signal for GPS, GLONASS, Galileo, BeiDou, QZSS, IRNSS
Connector: Type N female
Frequency:
L1/E1/B1/SAR: 1539 - 1627 MHz
L2/L2C: 1167 - 1255 MHz
L5/E5/B2: 1146 - 1234 MHz
E6/B3: 1215 - 1303 MHz
Number of output channels: 1 to 64
Channel configuration:
Any channel can be GPS, GLONASS, Galileo, BeiDou, QZSS, IRNSS
GLONASS freq ch -7 to +6
Up to 3 SBAS satellites (instead of 1-3 GNSS satellites)
Data format:
50 bits/s, GPS, Galileo OS, GLONASS frame structure
GPS CNAV
250 bits/s, SBAS
PRN codes: 1 to 210, plus GLONASS
Spurious transmission: <-40 dBc
Harmonics: <-40 dBc
6
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Output signal level:
-65 to -160 dBm;
0.1 dB resolution down to -150 dBm;
0.3 dB down to -160 dBm.
Power accuracy: ±1.0 dB
Pseudorange accuracy within any one frequency band: 1mm
Pseudorange accuracy across different frequency bands: 30 cm
Inter-channel bias: Zero
Inter-channel range: >54 dB
Limits:
Altitude: 18240 m (60000 feet)
Acceleration: 4.0 g
Velocity: 515 m/s (1000 knots)
Jerk: 20 m/s
3
1.2 Welcome
Extended limits:
Altitude: 20200 km
Acceleration: No limit
Velocity: 20000 m/s (38874 knots)
Jerk: No limit
White noise signal level:
-50 to -160 dBm
0.1 dB resolution down to -150 dBm
0.3 dB down to -160 dBm
±1.0 dB accuracy
1.2.5.2 Rear Outputs and Inputs
External Frequency Reference Input
Connector: BNC female
Frequency: 10 MHz nominal
Input signal level: 0.1 to 5V
Input impedance: >1kΩ
rms
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1.2 Welcome
Frequency Reference Output
Connector: BNC female
Frequency: 10 MHz sine
External Trigger Input
1/10/100/1000 PPS Output
1.2.5.3 Time Base
Standard OCXO
Output signal level: 1V
in to 50 Ω load
rms
Connector: BNC female
Signal Type: Single pulse
Level: TTL level, 1.4V nominal
Input impedance: >1kΩ
Minimum PW: 10 ms
Active Edge: Falling
Connector: BNC female
Output signal level: approx. 0V to +2.0V in 50 Ω load
Accuracy: Calibrated to ±10 nSec of RF timing mark output
Ageing per 24 h: <5x10
Ageing per year: <5x10
Temp. variation 20 … 50°C: <5x10
Short term stability (A
-10
-8
@1s): <5x10
dev
-9
-12
1.2.5.4 Optional Antenna
Frequency: 1000MHz to 2600MHz
Impedance: 50 Ω
VSWR: <2:1 (typ)
Connector: SMA male
Dimensions: 15 mm diameter x 36 mm length
8
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Page 25
1.2.5.5 Environmental
Environmental Data
Class: MIL-PRF-28800F, Class 3
Operat. Temp.: 0°C … +50°C
Storage Temp.: -40°C … +70°C, non-condensing, @ <12000 m
Humidity: 5-95% @ 10…30°C, 5-75% @ 30…40°C, 5-45% @ 40…50°C
Max. Altitude: 4600 m
Vibration: Random and sinusoidal according to MIL-PRF-28800F, Class 3
Shock: Half-sine 30g per MIL-PRF-28800F, Bench handling
Transit Drop Test: Heavy-duty transport case and soft carrying case tested
according to MIL-PRF-28800F
Reliability: MTBF 30000 h, calculated
Safety: Designed and tested for Measurement Category I, Pollution Degree 2, in
accordance with EN/IEC 61010-1:2001 and CAN/CSA-C22.2 No. 61010-1-04 (incl.
approval)
1.2 Welcome
EMC: EN 61326 (1997) A1 (1998), increased test levels per EN 50082-2, Group 1,
Class B, CE
Power Requirements
Line Voltage: 90-265 V
Power Consumption, 16-channel unit: <25 W
Power Consumption, 64-channel unit: <40 W
Dimensions & Weight
Width: ½ x 19" (215 mm)
Height: 2U (90 mm)
Depth: 395 mm
Weight: Net 2.7 kg (5.8 lb)
Shipping: 3.5 kg (7.5 lb)
, 45-440 Hz
RMS
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1.2 Welcome
BLANK PAGE.
10
CHAPTER 1 • User Guide GSG-5/6 Series Rev.22
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Setup
The following topics are included in this Chapter:
2.1 About Your Safety 12
2.1.1 Safety Precautions 12
2.1.2 Basic User Responsibilities 12
2.1.3 If in Doubt about Safety 13
2.2 Unpacking and Inventory 13
2.2.1 Unit Identification 14
2.3 Mechanical Installation 14
2.3.1 General Installation Considerations 14
2.4 Electrical Installation 21
2.5 Signal Power Level Considerations 22
2.5.1 Compliance: Using an Antenna 22
2.5.2 Transmit Power Level 23
CHAPTER 2
CHAPTER 2 • User Guide GSG-5/6 Series
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Page 28
Symbol Signal word Definition
DANGER!
Potentially dangerous situation which may lead to
personal injury or death!
Follow the instructions closely.
CAUTION!
Potential equipment damage or destruction!
Follow the instructions closely.
NOTE
Tips and other useful or important information.
ESD
Risk of Electrostatic Discharge! Avoid potential equipment
damage by following ESD Best Practices.
PROTECTIVEGROUND
Shows where the protective ground terminal is connected
inside the instrument.
Never remove or loosen this screw!
FUNCTIONALGROUND
Functional (noiseless, clean) grounding, designed to
avoid malfunction of the equipment.
CHASSIS GROUND
A terminal always connected to the instrument chassis.
2.1 About Your Safety
2.1 About Your Safety
The following safety symbols are used in Spectracom technical documentation, or on Spectracom
products:
Table 2-1:
Spectracom safety symbols
2.1.1 Safety Precautions
This product has been designed and built in accordance with state-of-the-art standards and the
recognized safety rules. Nevertheless, all equipment that can be connected to line power is a
potential danger to life. In particular, its use may constitute a risk to the operator or
installation/maintenance personnel, if used under conditions that must be deemed unsafe, or for
purposes other than the product's designated use, which is described in the introductory technical
chapters of this guide.
2.1.2 Basic User Responsibilities
To ensure the correct and safe operation of the instrument, it is essential that you follow generally
accepted safety procedures in addition to the safety precautions specified in this manual.
12
CHAPTER 2 • User Guide GSG-5/6 Series Rev.22
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2.2 Unpacking and Inventory
The instrument is designed to be used by trained personnel only. Removing the cover for repair,
maintenance, and adjustment of the instrument must be done by qualified personnel who are
aware of the hazards involved.
Note: The warranty commitments are rendered void if unauthorized access to the
interior of the instrument has taken place during the given warranty period.
Also, follow these general directions:
The equipment must only be used in technically perfect condition. Check components for
damage prior to installation. Also check for loose or scorched cables on other nearby
equipment.
Make sure you possess the professional skills, and have received the training necessary
for the type of work you are about to perform (for example: Best Practices in ESD
prevention.)
Do not modify the equipment, and use only spare parts authorized by Spectracom.
Always follow the instructions set out in this guide.
Observe generally applicable legal and other local mandatory regulations.
Keep these instructions at hand, near the place of use.
2.1.3 If in Doubt about Safety
Apply technical common sense: If you suspect that it is unsafe to use the product (for example, if it
is visibly damaged), do the following:
Disconnect the line cord.
Clearly mark the equipment to prevent its further operation.
Contact your local Spectracom representative.
2.2 Unpacking and Inventory
Caution: Electronic equipment is sensitive to Electrostatic Discharge (ESD).
Observe all ESD precautions and safeguards when handling the unit.
Unpack the equipment and inspect it for damage. If any equipment has been damaged in transit, or
you experience any problems during installation and configuration of your Spectracom product,
please contact your closest Spectracom Customer Service Center (see: "Technical Support" on
page 139).
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2.3 Mechanical Installation
The following items are included with your shipment:
GSG-5x/6x GNSS Simulator
Ancillary kit, GSG-5x/6x, containing:
CD with user’s manual, Protocol reference document & configuration SW
Compliance and shipping documentation
Optional: additional software and license key(s)
Note: Retain all original packaging for use in return shipments if necessary.
AC cord, 5-15P to C13, 18AWG, 10A, 125V
Adapter, SMA female–N male, 50 Ω
Cable assembly, SMA–SMA, 5ft.
USB 2.0 cable, with type A/B connector, 6ft.
2.2.1 Unit Identification
The type plate on the rear panel (see "Rear Panel" on page 30) of the unit includes the GSG
MODEL, PART No., and SERIAL No.
This information, as well as a list of installed options (if any), can also be found under the menu
item Options > Show system information.
2.3 Mechanical Installation
2.3.1 General Installation Considerations
Orientation
GSG-Series units can be operated in any position, i.e. horizontal, vertical, or at any angle.
Cooling
The air flow through the side ventilation openings must not be obstructed.
Leave 5 cm (2") of space around the unit.
14
Bench-Top Setup
For bench-top use, a fold-down support is available for use underneath the GNSS Simulator. This
support can also be used as a handle to carry the instrument.
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2.3 Mechanical Installation
Figure 2-1: Fold-down support
Single-Unit Rack-Mount Installation
With the optional Spectracom 22/90 rack-mount kit (P/N 9446- 1002-2901) one GSG unit can be
installed in a 19-inch rack (2U). The kit comprises:
2 ears, one of which with a pre-assembled face-plate spacer
4 screws, M5 x 8
4 screws, M6 x 8.
Figure 2-2: Rack-Mount Kit (the GSG housing shown in the center is not part of the kit)
In order to prepare the GSG unit for rack-mount installation, the housing needs to be opened, in
order to remove the bottom feet (otherwise the assembly will not fit in a 2U slot.)
DANGER! Do not perform any work on the internal components of the unit, while the
housing is removed, unless you are qualified to do so. Before removing the cover,
unplug the power cord and wait for one minute to allow any capacitors to discharge.
1.
After making sure that the power cord has been unplugged, carefully turn the unit upside
down.
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2.3 Mechanical Installation
2.
Temporarily remove the two rear feet by loosening their screws.
3.
Remove the four housing screws and plugs (if present) at the side panels, and discard
them.
4.
Grip the front panel with one hand, while pushing at the rear with the other hand. Pull the unit
out of its housing.
5.
Remove the four bottom feet from the housing, as shown in the illustration below:
Use a screwdriver or a pair of pliers to remove the springs holding each foot, then push out
the foot.
Figure 2-3: Preparing the GSGunit for rack mounting
6.
Gently push the unit into its housing again.
7.
Re-assemble the two rear feet.
8.
Install the ears that came with the rack-mount kit. Use the rack-mount kit M5 housing
screws.
Figure 2-4: Part identification: ears
16
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2.3 Mechanical Installation
Note: The unit can also be installed on the right-hand side of the rack by
reversing the two ears.
9.
Depending on accessibilty in your rack, you can connect the cables to the GSG unit now, or
after installation of the assembly in the rack. For electrical installation, see "Electrical
Installation" on page 21.
10.
Install the assembly in your rack, using the M6 screws that came with the rack-mount kit.
11.
Complete the electrical installation.
Side-by-Side Rack-Mount Installation
With the optional Spectracom 22/05 rack-mount kit (P/N 1211- 0000-0701 ), two GSG units can
be installed side-by-side in one 19-inch rack (2U). The kit comprises:
4 x Bracket, rear (1211-1000-0706) [Item 1]
2 x Ear, rack (1211-1000-0714) [Item 2]
1 x Hinge, right half (1211-1000-0709) [Item 3]
1 x Hinge, left half (1211-1000-0709) [Item 4]
8 x Screw, oval head phil, M5x10mm (HM25R-D5R8-0010) [Item 5]
2 x Screw, pan head phil, M4x8mm (HM10R-04R0-0008) [Item 6]
1 x Spacer, Hex, M4x16 (HM50R-04R0-0016) [Item 7]
Figure 2-5: Dual rack-mount assembly
In order to prepare the GSG units for rack mount installation, the housings needs to be opened, in
order to remove the bottom feet (otherwise the assembly will not fit in a 2U slot.)
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2.3 Mechanical Installation
1.
After making sure that the power cord has been unplugged, carefully turn the first GSG unit
upside down.
2.
Remove the two rear feet. Keep the screws, discard the brackets.
3.
Remove the four housing screws and plugs (if present) at the side panels, and discard
them.
4.
Grip the front panel with one hand, while pushing at the rear with the other hand. Pull the unit
out of its housing.
5.
Remove the four bottom feet from the housing, as shown in the illustration below:
Use a screwdriver or a pair of pliers to remove the springs holding each foot, then push out
the foot.
DANGER! Do not perform any work on the internal components of a GSG unit, while
the housing is removed, unless you are qualified to do so. Before removing the
cover, unplug the power cord and wait for one minute to allow any capacitors to
discharge.
18
Figure 2-6: Preparing a GSG unit for rack mounting
6.
Gently push the unit into its housing again.
7.
Install the rear brackets supplied with the mounting kit (item no. 1) where the rear feet were
previously attached (see illustration "Dual rack-mount assembly" above). Use the screws
saved in step 2.
8.
Repeat the procedure described above for the second unit.
9.
Using a Philips-head screwdriver, screw the rack ears (item no. 2) into place, using the
supplied 10-mm screws (item no. 5).
10.
Pinch the hinge pins together, to separate the right and left hinge halves (items no. 3 and 4).
11.
Attach hinge halves to the unit with the hinge facing towards the front.
12.
Pinch the hinge pins together into the stored position. Align the hinge halves together
between the two units, and swing together side by side. The hinge pins should snap into
place, securing the front of the two units.
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2.3 Mechanical Installation
13.
In the back of the unit, take the supplied Hex Spacer (item no. 7), and place between middle
rear brackets, and secure using the supplied 8-mm screws (item no. 6).
14.
Assembly is now ready for installation into standard 19" rack.
15.
Depending on accessibility, you can complete the electrical installation before or after
installing the assembly in the rack. For electrical installation, see "Electrical Installation" on
page 21.
Rack-Mount Installation with an Agilent Power Meter
GSG units are frequently installed adjacent to an Agilent Power Meter , using one 19" slot (2U).
This can be accomplished with the optional Spectracom 22/04 rack-mount kit (P/N 9446- 1002-
2041). Also required is the Agilent rack-mount kit.
Note: This kit can also be used to install only one GSG unit in a 19" rack 2U slot,
similar to the optional Spectracom 22/90 Rack-Mount Kit (P/N 9446-1002-2901).
Figure 2-7: 22/04 Rack-mount kit
In order to prepare the GSG unit for rack mount installation, the housing needs to be opened, in
order to remove the bottom feet (otherwise the assembly will not fit in a 2U slot.) The same may be
necessary for the Agilent unit – follow the manufacturer's instructions.
1.
After making sure that the power cord has been unplugged, carefully turn the GSG unit
upside down.
2.
Temporarily remove the two rear feet by loosening their screws.
3.
Remove the four housing screws and plugs (if present) at the side panels, and discard
them.
4.
Grip the front panel with one hand, while pushing at the rear with the other hand. Pull the unit
out of its housing.
5.
Remove the four bottom feet from the housing, as shown in the illustration below:
Use a screwdriver or a pair of pliers to remove the springs holding each foot, then push out
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2.3 Mechanical Installation
the foot.
6.
Gently push the unit into its housing again.
7.
Re-assemble the two rear feet.
8.
Decide on which side of the assembly the GSG unit is to be installed: If on the left-hand
side, install the short ear to the left hand side of the GSG unit, using the rack-mount kit M5
housing screws.
Figure 2-8: Preparing the GSGunit for rack mounting
Note: The instructions below are based on the assumption that the GSG unit
is installed on the left-hand side of the assembly.
9.
Install the front assy plate to the Agilent unit, as shown in the illustration below. Use the
screws from the Agilent rack-mount kit.
Take two of the plastic snap caps from the GSG rack-mount kit, remove and discard the
caps, and install the sleeves into the housing screw openings.
Slide the Agilent unit and the GSG unit together, so that the protruding pins of the front assy
plate fit into the sleeves.
Figure 2-9: Front assembly plate installation Agilent unit (shown left), GSG unit
20
10.
Install the rear assy plate, Agilent, and the rear assy plate, GSG, and assemble them, as
shown in the illustrations below.
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2.4 Electrical Installation
Figure 2-10: Installation of rear assembly plates
11.
Equivalent to Step 8., install the front panel ear plate (Agilent rack-mount kit) to the Agilent
power meter.
12.
The assembly is now complete, and can be installed in the cabinet.
2.4 Electrical Installation
Supply Voltage
GSG Series simulators may be connected to any AC supply with a voltage rating of 90 to
265V
Fuse
The secondary supply voltages are electronically protected against overload or short circuit. The
primary line voltage side is protected by a fuse located on the power supply unit. The fuse rating
covers the full voltage range. Consequently there is no need for the user to replace the fuse under
any operating conditions, nor is it accessible from the outside.
, 45 to 440 Hz. The units automatically adjust themselves to the input line voltage.
RMS
Caution: If this fuse is blown, it is likely that the power supply is badly damaged. Do
not replace the fuse. Send the GSG unit to your local Service Center.
DANGER! — Removing the cover for repair, maintenance and adjustment must be
done by qualified and trained personnel only, who are fully aware of the hazards
involved.
The warranty commitments are rendered void if unauthorized access to the interior of the
instrument has taken place during the warranty period.
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2.5 Signal Power Level Considerations
Grounding
Grounding faults in the line voltage supply will make any instrument connected to it dangerous.
Before connecting any unit to the power line, you must make sure that the protective ground
functions correctly. Only then can a unit be connected to the power line and only by using a threewire line cord. No other method of grounding is permitted. Extension cords must always have a
protective ground conductor.
Caution: If a unit is moved from a cold to a warm environment, condensation may
cause a shock hazard. Ensure, therefore, that the grounding requirements are
strictly met.
DANGER! — Never interrupt the grounding cord. Any interruption of the protective
ground connection inside or outside the instrument or disconnection of the protective
ground terminal is likely to make the instrument dangerous.
Electrical Connections
For a graphic representation of all electrical connections, see "Rear Panel" on page 30 and "Front
Panel" on page 27.
Using any of the communication interfaces is not required for GSG to operate in a basic mode.
The same applies to the outputs for 1PPS and 10MHz, as well as the inputs EXT REF FREQ and
EXT TRIG: Their usage is not compulsory for basic operation.
The minimum electrical configuration for any test layout requires only the power cord and an RF
antenna cable— or an actual GNSS antenna—to connect the GSGunit to your receiver-under-test
(using the front panel RF connector, see "Front Panel" on page 27.)
2.5 Signal Power Level Considerations
2.5.1 Compliance: Using an Antenna
Spectracom’s GSG GNSS Simulator products meet all required regulations of the FCC and CE
Mark for operation as electronic test equipment. However, when using the GSG signal generator
with an RF antenna (instead of an RF cable), additional regulations controlling the radiation of
GPS-like signals into the air must be taken into account by the user:
In the USA, the GPS spectrum is controlled by the National Telecommunications and
Information Administration (NTIA): See Sections 8.3.28 and 8.3.29 of the Manual of Regulations
and Procedures for Federal Radio Frequency Management
(http://www.ntia.doc.gov/osmhome/redbook/redbook.html).
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Depending on your situation, you may need authorization from the FCC to operate at or near the
Antenna distance to nearest exterior wall: 100 ft.
Antenna gain: 0 dB (omni antenna)
Cable loss, antenna to GSG: 0 dB (no cable used)
level allowed by the NTIA. A Special Temporary Authorization (STA) or Experimental License may
be required.
For more information, see the FCC web site: https://fjallfoss.fcc.gov/oetcf/els/.
Countries other than the USA may have their own regulations or restrictions, which you should be
aware of and comply with before using the optional antenna.
2.5.2 Transmit Power Level
The U.S.agency NTIA (National Telecommunications & Information Administration) restricts the
maximum signal level to -140 dBm (24 MHz BW) as received from an isotropic antenna at a
distance of 100 feet from the building where the test is being conducted. Therefore, the maximum
power level output from the GSG Signal Generator may need to be limited to conform to this
regulation.
For example, consider the following test setup:
2.5 Signal Power Level Considerations
Using the free space loss calculation for radio propagation:
Loss (dB) = 20 log10 (4ᴫ * Distance / λ)
Where λ = wavelength: @ 1575 MHz= 19 cm = 0.62 ft
Distance = 200 ft total => 100 ft from antenna exterior wall + 100 ft to restricted
perimeter
Loss = 72 dB = 20 log10 (4ᴫ * 200/0.62)
Using the free space calculation is a worst case scenario as the wall and any other obstructions
will likely reduce the signal even more. Therefore, setting the power output of the GSG to:
-140 + 72 = -68 dBm or less will guarantee compliance.
For additional information on path loss, see also this third- party reference1:
http://en.wikipedia.org/wiki/Path_loss
1
This link is provided for reference purposes only. It leads to a web page that is not maintained or supported by Spectracom.
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2.5 Signal Power Level Considerations
BLANK PAGE.
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CHAPTER 3
Features & Functions
This Chapter contains descriptions and reference information of the
functional elements of both the GSG hardware, and software.
The following topics are included in this Chapter:
3.1 Front Panel 27
3.1.1 Description of Keys 28
3.1.1.1 Power 28
3.1.1.2 Start 28
3.1.1.3 Exit 28
3.1.1.4 Cancel 28
3.1.1.5 Menu 28
3.1.1.6 View 29
3.1.1.7 Enter 29
3.1.1.8 Arrows 29
3.1.1.9 N/S 29
3.1.1.10 E/W 29
3.1.1.11 Numeric Keys 29
3.1.1.12 +/– (format) 29
3.1.1.13 [.] (hold) 30
3.2 Rear Panel 30
3.3 The GSG Main Menu 31
3.4 "Start" Menu 32
3.4.1 Scenario Start Variations 33
3.4.2 Scenario Execution Views 33
3.4.2.1 View 1/x 34
3.4.2.2 View >1/x 34
3.4.2.3 Last View 37
3.5 "Select" Menu 37
3.5.1 Start Time 39
3.5.2 Duration 40
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3.5.3 Latitude, Longitude, Altitude 41
3.5.4 Trajectory 41
3.5.4.1 Predefined Trajectories 42
3.5.4.2 Trajectory Files 43
3.5.4.3 Timestamp Usage in Trajectories 44
3.5.5 Ephemeris 45
3.5.5.1 Default Ephemeris 45
3.5.5.2 Download Ephemeris 46
3.5.5.3 User-Uploaded Ephemeris 46
3.5.6 Leap Second 49
3.5.7 Event Data 50
3.5.8 Antenna Settings 55
3.5.8.1 Antenna model 55
3.5.8.2 Lever arm 56
3.5.8.3 Elevation mask 56
3.5.9 Advanced Configuration Options 57
3.5.9.1 Multipath signals 57
3.5.9.2 Interference signals 59
3.5.9.3 Base station 62
3.5.9.4 Environment models 63
3.5.9.5 Atmospheric model 66
3.5.10 Satellite Configuration 68
3.5.10.1 Satellite Systems 69
3.5.10.2 Number of Satellites 69
3.5.10.3 Frequency Bands and Signal De-/Activation 70
3.5.10.4 Satellite Constellations 72
3.5.10.5 Encryption 74
3.5.10.6 SBAS Satellites 75
3.6 "Options" Menu 78
3.6.1 Transmit Power 78
3.6.1.1 External Attenuation 80
3.6.1.2 Noise Generation 81
3.6.2 Signal Generator 83
3.6.2.1 Signal type 84
3.6.2.2 Satellite ID 85
3.6.2.3 Transmit power 85
3.6.2.4 Frequency offset 86
3.6.2.5 Start time 86
3.6.2.6 Ephemeris 86
3.6.2.7 AutoStart 86
3.6.3 Interface and Reference 87
3.6.3.1 Network Configuration 88
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3.6.3.2 Proxy Configuration 89
3.6.4 Manage Files 90
3.6.5 Show System Information 92
3.6.6 Restore Factory Defaults 92
3.6.7 Calibration 93
3.1 Front Panel
All GSG-5/6 simulators have similar front panels. On the right side are the controls used for
managing scenario execution and for display navigation . At the bottom are the numeric keys
used to input scenario parameters and other configuration.
3.1 Front Panel
Figure 3-1: GSG front panel
There are three status indicators on the front panel. When the unit is idle, all three indicators are
off.
scenario will blink when a scenario is running
armed (or: trig) is lit when the unit is armed, i.e. waiting for a trigger signal to start executing
a scenario
rf-out is lit when there is signal coming out of the RF-connector on the front panel.
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3.1 Front Panel
Note: The N-type RF-connector is equipped with a DC block to prevent the flow of
direct current up to 7VDCin order to protect the GSG unit.
3.1.1 Description of Keys
3.1.1.1 Power
The ON/OFF key is a toggling secondary power switch. Part of the instrument is always ON as
long as power is applied, this standby condition is indicated by a red LED above the key. This
indicator is consequently not lit while the instrument is in operation.
3.1.1.2 Start
3.1.1.3 Exit
3.1.1.4 Cancel
3.1.1.5 Menu
Press start to start the currently selected scenario.
In the Signal Generator menu, press start to start transmitting.
When editing a field, press exit to end the editing process, and save your changed field
value. The field label will be highlighted.
When
not
editing a field, press exit to return to the previous display, and save the
changes you applied to the current display. Confirm your changes.
When running a scenario, press exit to stop the scenario execution (same as cancel).
When editing a field, press cancel to abort the editing process, and discard any field
changes. The field label will be highlighted instead.
When
not
editing a field, press cancel to return to the previous display, and discard any
changes you applied to the current display. Confirm your cancellation.
When running a scenario, press cancel to stop the scenario execution (same as exit).
28
When running a scenario, press menu to display the main scenario configuration (the
scenario will continue to run.)
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3.1.1.6 View
3.1.1.7 Enter
3.1 Front Panel
When reviewing/editing configuration settings, press menu to exit the current sub-menu,
and return to the main menu, regardless of the current display. You will be asked to save
your changes (same as exit).
When running a scenario, press menu to display the configuration of the scenario currently
running.
When running a scenario, press view to toggle between the available views.
In the main menu, pressing view will act as a shortcut to the configuration display of the
currently selected scenario.
In the Options menu, press view to make a selection (same as enter).
Press enter to make a selection.
3.1.1.8 Arrows
Press any of the arrow keys to navigate in displays.
When editing an integer value, press the UP/DOWN arrows to incrementally increase or
decrease the value.
3.1.1.9 N/S
When editing latitude, press N/S to toggle between north and south latitude.
During scenario execution, press N/S to open the transmit power menu, in order to adjust
the scenario's noise settings.
3.1.1.10 E/W
When editing longitude, press E/W to toggle between east and west longitude.
3.1.1.11 Numeric Keys
Press the numeric keys to input numbers.
3.1.1.12 +/– (format)
When editing numbers, press +/– (format) to toggle between the positive and negative
value.
When configuring or executing a scenario, press +/– (format) to change the coordinate
format between geodetic coordinates, andECEF format.
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3.2 Rear Panel
In scenario execution, View 2/5 and higher, press +/– (format) to switch between
frequency bands (L1, L2 and L5).
3.1.1.13 [.] (hold)
Use the "DOT" [.] (hold) key together with numeric keys, where appropriate.
During scenario execution, press the [.] (hold) key to hold/resume the simulated
movement (trajectory).
While a scenario is loading, press the [.] (hold) key to initiate a scenario arming from the
front panel.
3.2 Rear Panel
As a means for communication, GSG supports GPIB, USB and Ethernet . Only one connection
can be active at a time. The active connection is selected under Options > Interface. The default
setting is Ethernet.
The illustration below shows the connections available on the back side of the unit:
30
Figure 3-2: GSG rear panel
1.
1PPS Output: TTL level signal with positive slope timed to GPS time of RF out (can be
programmed as 10/100/1000PPS).
2.
Reference Output: 10 MHz derived from the internal or—if present—external reference.
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3.3 The GSG Main Menu
3.
External Reference Input: Can be selected as a reference via the Interface and
Reference menu.
4.
External Trigger Input: Optional signal input for scenario triggering.
5.
GPIB Connector: The address is set in the Interface and Reference menu.
6.
Ethernet Connector: Data communications port used with TCP/IP networks.
7.
USB Connector: Data communications port used with Personal Computers.
8.
Line Power Inlet: AC 90-265 V
9.
Protective Ground Terminal: The protective ground wire is connected at this location
inside the instrument. Never tamper with this screw!
10.
Fan: The fan speed is controlled via a temperature sensor. Normal bench-top use means
low speed, whereas rack-mounting and/or installed options may result in higher speed.
11.
Type Plate: Indicates model number and serial number.
. 45-440 Hz; automatic input voltage selection.
RMS
3.3 The GSG Main Menu
The main menu of the GSG user interface is shown on the GSG display when the unit is started.
To return to the main menu from any of the sub menus, press the menu key.
Figure 3-3: GSG's main menu
Main menu description:
1.
Main menu options: Start, Select, Options
2.
GSG model number (for more information on models and configurations, see "GSG Series
Model Variants and Options" on page 136).
On the right side of the menu, the currently selected scenario is shown with some of its key data:
3.
Name of the current scenario (see also: )
4.
Scenario start date
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3.4 "Start" Menu
5.
Transmit RF power (see also: "Adjusting Transmit Power" on page 101)
6.
Trajectory shape
7.
Scenario Current Position (latitude/longitude)
8.
In the upper right-hand corner, abbreviations may be shown:
3.4 "Start" Menu
To start the currently loaded scenario (as previously selected using the ""Select" Menu" on page
37), highlight the main menu option Start by pressing the arrow keys. Then press enter.
In its default mode, the GSG simulator will launch the scenario (the delay depends on the
size/complexity of the scenario data), and then automatically run the scenario.
To stop the scenario, press exit or cancel, and confirm.
There are, however, interesting alternatives to starting a scenario, mainly to facilitate test
automation. The illustration below summarizes the start variations discussed underneath.
REM : remote commanding
EXTREF : external reference clock is selected in the Options menu
ARM : the unit is waiting for a trigger to start the scenario
HOLD : the movement along the trajectory is paused
32
Figure 3-4: Scenario start variations – Flowchart
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3.4.1 Scenario Start Variations
Hold before manual start
Once you pressed start, or enter (with the Start main menu option highlighted), the GSG unit
requires some time to launch the scenario (the delay depends on the size/complexity of the
scenario data). During this wait time, you can press the [.] (hold) key to prevent the scenario from
beginning to run before you are ready. This is referred to as arming (the ARM text icon will display
in the upper right corner of the display, and the armed status indicator will light up).
Once you are ready, press the start key to run the armed scenario.
SCPI START command
Once you submitted the SCPIcommand SOURce:SCENario:LOAD , submit another
command to arm the GSG simulator:
SOURce:SCENario:CONTrol ARM.
Then, to start scenario execution, submit the SCPI start command:
SOURCce:SCNario:CONTrol START.
3.4 "Start" Menu
Start via external trigger
After arming a loaded scenario (see above), the scenario execution can be started via an external
trigger signal, submitted to the GSG unit by means of the BNC input (see "External Trigger Input"
under "Rear Outputs and Inputs" on page 7).
3.4.2 Scenario Execution Views
While a scenario is running (also referred to as "scenario execution"), you can display several
views, so as to …
monitor the current scenario status
verify the operation of your receiver-under-test by comparing its output with the data
provided in the scenario execution views
adjust some of the scenario settings.
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3.4 "Start" Menu
Figure 3-5: Views displayed during scenario execution
To display the views in successive order, press the view key. In the lower right corner, e.g. View
2/6 may be displayed, indicating the current view/total number of views. The total number, and
content of views depends on the number of signals used in the scenarioa maximum of 5 in
GSG-52 and GSG-53, 8 in GSG-54, 16 in GSG-55 and GSG-56,32 in GSG-62, 48 in GSG-63, and a
maximum of 64 in GSG-64. GSG-5 maximum channels vary by channel option purchased.
See "Running a Scenario" on page 96 to find out how you can interact with the system during
scenario execution, and to learn which scenario settings can be adjusted.
3.4.2.1 View 1/x
View 1/x displays the scenario name, and information about the simulation GPS date and time ,
current position, speed and direction, and elapsed time.
3.4.2.2 View >1/x
Views >1/x display information pertaining to the individual simulated satellites. Up to 8
channelsThe number of channels is 1 to 64, depending on the configuration of your GSG unit. are
shown per view.
The first line repeats the …
… GPS date and time (as in View 1/x), and displays the …
… HDoP (Horizontal Dilution of Precision): A dimensionless number indicating the relative
quality of the calculated horizontal position, which is largely a function of the current
satellite constellation. [A smaller number is better; the number will never be 0 or 2.]
Note: When you press the exit key to leave a menu, its settings will be taken into
use immediately, and all band- or satellite-specific offsets are discarded.
34
The remaining lines are:
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1.
In view: Shows the abbreviation of each satellite system, followed by its number of
satellites in view/GSG channels reserved. Satellite system abbreviations are:
GP: GPS
GL: Glonass
GA: Galileo
BD: BeiDou
IR: IRNSS
3.4 "Start" Menu
QZ: QZSS
2.
PRN: Pseudo-Range Number (satellite identifier). The identifiers are:
For GPS: Gxx
For Galileo: Exx
For GLONASS: Rxx
For BeiDou: Cxx
For QZSS: Jxx
For IRNSS: Ixx
For SBAS: Sxxx.
Letters are lower case if a satellite is unhealthy, or if the ephemeris data is too old to be
used.
For multipath replicas, the letter 'D' will be displayed next to the satellite number.
Fading satellite signals are indicated by the letter ‘F’ (see end of Chapter "Propagation
Environment Models" on page 64 for more information).
Interference signals are recognized by their elevation and azimuth fields since these will
be marked as *.
Furthermore, when the interference signal is un-modulated this is identified by a CG for
GPS interference signals and a leading C letter followed by the frequency slot number for
GLONASS interference signals.
Hence, next to the identifiers listed above, the following identifiers may also be displayed:
iUG, for unmodulated GPS interference signal
iUE, for unmodulated Galileo interference signal
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3.4 "Start" Menu
iUC, for unmodulated BeiDou interference signal
iUJ, for unmodulated QZSS interference signal
iUx, for unmodulated GLONASS interference signal, where ‘x’ is the frequency slot
ranging from -7 to 6
iSg, for sweeping GPS interference
iSr, for sweeping Glonass interference
iSe, for sweeping Galileo interference
iSc, for sweeping BeiDou interference
iSj, for sweeping QZSS interference
iNg, for noise GPS interference
iNr, for noise Glonass interference
iNe, for noise Galileo interference
iNc, for noise BeiDou interference
iNj, for noise QZSS interference
4.
ELV: Satellite elevation
The angle between the current position's horizontal plane and the satellite position. A
low angle is close to 0°, a high angle close to 90° [range = 0 to 90°]
5.
AZM: Azimuth
The angle around the vertical axis of the current position [north = 0°, east = 90°,
south = 180°, west = 270°]
6.
dBM: decibel Milliwatt
Transmit Power ratio in decibels for the frequency band indicated (L1, L2, L5 and
ALL). During scenario execution, the Transmit Power (= signal level) can be
adjusted for all satellites per frequency band (including ALL bands), or per individual
satellite:
This power adjust functionality is useful for fine tuning the scenario power level
(see also "Adjusting Transmit Power" on page 101).
Adjustments to dbALL are saved to the transmit power so that when a scenario is
run next time the power is as desired.
Press ±/format to toggle through the frequency bands;
to adjust the power for all satellites on the current band, press ±/power.
Press LEFT/RIGHT arrow keys to select a satellite. An information box is
displayed, showing the satellite ID, elevation, azimuth and frequency bands
in use.
To adjust the Transmit Power for this satellite, press the UP/DOWN arrow
keys. Press enter to confirm.
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3.5 "Select" Menu
Changing the Transmit Power setting becomes effective immediately, and also
impacts noise generation levels (if in use – available with GSG-5, GSG-55, GSG-56
and GSG-62, 63, and 64).
E x a m p l e
The example above illustrates two GPS signals (G23 and G5), one SBAS signal (S135), one
multipath signal (G7D) and one interference signal (G3).
3.4.2.3 Last View
The last view (e.g. View 4/4 ) shows a skyplot, illustrating how the simulated satellites are located
in the sky.
Press the LEFT/RIGHT arrow keys to scroll through the skyplots, if more than 2 constellations are
simulated.
The center of the plot represents the current receiver position, ant the outermost circle the horizon,
i.e. the elevation of a satellite located near this circle is low. The lines represent the azimuth
(North=0°). For example, in the GAL ileo plot shown above, satellite number 22 would have an
elevation of approximately 45°, and an azimuth near 300°.
3.5 "Select" Menu
Scenarios are the simulation scripts which you run on the GSGsimulator in order to test a GNSS
receiver. GSGhas pre-installed scenarios which can be executed 'as is', or which you can reconfigure to adapt them to your needs. You can also create your own scenarios using the optional
GSG StudioView Software (see "GSG StudioView Software" on page 135).
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3.5 "Select" Menu
Prior to running a scenario, you have to select it from the list of scenarios installed on the GSG
unit:
1.
In the Main Menu, highlight Select using the arrow keys, then press enter to display the list
of scenarios currently loaded:
2.
Scroll through the list by using the UP/DOWN arrow keys. Select the highlighted scenario
(for a list of standard scenarios, see ) by pressing enter or view: The first Configuration
View will be displayed:
1.
If you want to modify the configuration of the scenario, see "Configuring a Scenario" on
page 97 for detailed instructions.
2.
To execute (= run) the selected scenario, press the start key: The scenario will be launched
(which will take a moment, depending on the complexity of the scenario chosen), and then
started automatically, unless you pressed the [.]/hold key.
Below is a list of all configurable scenario parameters which can be accessed via the Select
Scenario menu, and which are discussed in the following topics.
Note: Options that are grayed out on your GSGunit are not installed.
"Start Time" on the facing page
"Duration" on page 40
"Latitude, Longitude, Altitude" on page 41
"Trajectory" on page 41
"Ephemeris" on page 45
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"Leap Second" on page 49
"Event Data" on page 50
"Antenna Settings" on page 55
"Advanced Configuration Options" on page 57
"Multipath signals" on page 57
"Interference signals" on page 59
"Base station" on page 62
"Environment models" on page 63
"Atmospheric model" on page 66
"Satellite Configuration" on page 68
"Satellite Systems" on page 69
"Number of Satellites" on page 69
"Frequency Bands and Signal De-/Activation" on page 70
"Satellite Constellations" on page 72
3.5 "Select" Menu
3.5.1 Start Time
Start time is the time a scenario uses for simulation purposes, i.e. the simulated time at which the
scenario begins every time it is run. The Start time can be …
a.
a set time, as configured for the scenario. Whenever you start this particular scenario, the
previously set Start time will be used, e.g. November 4, 2015 at 19:30.
b.
real time, as derived from the NTP server specified in the Network Configuration, and
triggered by the user pressing start, or a SCPI start signal being submitted.
The Start time is aligned to the next full GPS minute. The NTP (UTC) timescale is
converted to the GPS timescale by a UTC-GPS offset defined in the NTP Server settings.
GPS time and leap seconds
The Start time is based on GPS time, i.e. the displayed time is always GPS time. Unlike UTC
time – which is frequently displayed by GNSS receivers – GPS time does
seconds.
"Encryption" on page 74
"SBAS Satellites" on page 75
Note: If NTP real time is used, the scenario start will be delayed by up to
2minutes, in order to allow for the simulation data to be loaded.
not
include leap
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3.5 "Select" Menu
NTP real time and downloaded Ephemeris
Using NTP as start time in conjunction with Ephemeris set to Download is subject to licensing
options, as it requires the Simulate Now option to be present. In this configuration, the GSG unit
will simulate the sky as it is in that start position at current time. This functionality is currently only
available for the GPS constellation. Please also note that the availability of good ephemeris data
cannot be guaranteed, and periods where no data is found and hence no signals can be generated,
may occur.
About GPS time and GPS week number
In the GPS data format, there are 10 bits reserved to represent the GPS week number, which leads
to a modulo 1024 ambiguity in the week number and hence the GPS date:
The GPS week number count began at midnight of January5/6,1980. Since then, the count has
been incremented by "1" every week, and broadcast as part of the GPS message. Consequently,
at the completion of week 1023, the GPS week number will roll-over to week number 0.
This means that if looking only at the week number (WN) parameter in the GPS data message, it is
impossible to determine if WN 1023 corresponds to August1999, or April2019, etc. GPS receivers
must therefore account for this roll-over problem, and use other means to decide on which 1024
week period they currently are in.
The designers of GPS receivers have a number of ways of ensuring that the WN is interpreted
correctly. These techniques range from keeping GPS week numbers in non-volatile memory,
keeping a real-time clock, etc.
One popular method involves resolving the year period ambiguities with software revision dates.
For example: Since the GPS software knows that it was made on February11, 2011
(corresponding to GPS week number1622, and in the data message WN598), this information can
be used to map the WN to a year by concluding that e.g., WN597 cannot correspond to early
February2011, but rather to mid-September 2030.
This in turn, means that when simulating scenarios using a simulator, going back and forth in time
and in GPS week numbers, you may see unexpected behavior in how the WN is interpreted. This
could result in a scenario that worked ‘correctly’ in the past, starts outputting a different date that is
19.7 years forward in time.
GLONASS time differs from GPS time in such that it has the same leap seconds inserted as UTC
has. Hence, the GLONASS system does not have the week roll-over problem that GPS has.
When simulating scenarios with historical dates, however, it is likely that a receiver that is trying to
compensate for the week roll-over based on the firmware build date mentioned above, will get into
a conflict with the GLONASS time stamps and in this case the receiver will not output any
solution. This issue, especially with combined GPS+GLONASS scenarios, can be avoided by
simulating future dates.
3.5.2 Duration
The duration of the scenario replay can be set to a number of days, hours and minutes.
Any scenario can be run in three different modes:
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Looping: The scenario will be replayed infinite times, re-starting every time after its set
duration has expired.
For this mode, the trajectory should be loop- shaped, i.e. have the same start/end point.
Otherwise, an error will likely be thrown once the receiver-under-test upon the first replay is
moved from the end point to the start point in an unrealistically short time.
Forever: The scenario will run infinitely (the duration time will be grayed out).
If your trajectory is loop-shaped, i.e. it has the same start/end point, the trajectory will be
followed over and over again (just like in the above-mentioned Looping mode), but the
simulation time will continue to elapse (contrary to the Looping mode, which will re-start
the simulation time with every new scenario execution.
If your trajectory is
trajectory vector infinitely.
not
loop-shaped, in this mode the receiver will travel along the last
Note: The option Endless only works, if the ephemeris option is set to
Download. (See also:"Ephemeris" on page 45)
One-Go: The scenario will be executed once, for the set duration.
Upon completion of the scenario execution, GSG will return to the Main menu.
3.5.3 Latitude, Longitude, Altitude
The position is specified using WGS84 (for more information on the
Wikipedia).
Note that the use of the WGS standard also applies to the altitude (ellipsoid height), and that this
altitude is NOT the same as the MSL often output by receivers.
Select a different coordinate input format by pressing the +/– (format) key repeatedly. The
choices are:
decimal degrees
degrees-minutes
degrees-minutes-seconds
ECEF (Earth-Centered, Earth-Fixed) format.
3.5.4 Trajectory
Note: This feature is not available in GSG-51/52/53.
World Geodetic System
, see
A trajectory is a path in space that a moving device follows as a function of time. GSG-5/6 can be
used to simulate virtually any user trajectory. You can:
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use pre-defined/built in trajectories
modify pre-defined/built in trajectories (in GSG, or using the GSG Studioview software)
create trajectory files in StudioView, and upload them.
Note: If the RSG License Option is installed, you can also control movement in real-
time over the protocol.
At the start of the scenario the nose of the user is pointing north. The orientation of the vehicle body
changes with movement so that its nose is aligned with the vehicle’s course. In cases with
changing altitude the nose will still point in a horizontal direction, not changing the body attitude.
This default behavior can be changed by using SCPI commands, which change pitch/roll/yaw of
the simulated vehicle.
3.5.4.1 Predefined Trajectories
The exact list of predefined trajectories varies from GSG model to model. The following is a
selection.
Static: The user is not moving, but the latitude, longitude and altitude defined in the
Scenario configuration are used as user position throughout the scenario replay.
3GPP: The user is moving on a rectangular trajectory as defined in the Technical
Specification 3GPP TS 25.171 V7.1.0, Section 5.5, Table 11 and Figure 1:
T h e s p e c i f i c a t i o n d e s c r i b e s t h e t r a j e c t o r y
a s f o l l o w s :
“The UE moves on a rectangular trajectory of 940 m by 1440 m with rounded corner
defined in figure 1. The initial reference is first defined followed by acceleration to final
speed of 100 km/h in 250 m. The UE then maintains the speed for 400 m. This is
followed by deceleration to final speed of 25 km/h in 250 m. The UE then turn 90
degrees with turning radius of 20 m at 25 km/h. This is followed by acceleration to final
speed of 100 km/h in 250 m. The sequence is repeated to complete the rectangle.”
42
The complete specification can be found here: http://www.3gpp.org/DynaReport/25-
series.htm
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Circle: The user is moving in a circle throughout the scenario replay. When Circle is
selected, a dialog is shown asking the parameters describing this trajectory. These
parameters include diameter [meter], speed [m/s] and direction [clockwise/anticlockwise].
The start position of the trajectories is the position specified in the Configuration View1/3 ,
under Latitude, Longitude and Altitude.
3.5.4.2 Trajectory Files
GSG supports the simulation of customer-made trajectories. The trajectories are typically created
with the GSG StudioView software.
Two types of trajectory files are supported:
3.5 "Select" Menu
NMEA Trajectories
Custom trajectories can be used by uploading NMEA files to your GSG unit from a WindowsPC.
NMEA trajectories are
the same trajectory can be re-played in different scenarios, using different starting positions.
The NMEA trajectory files can be configured either to be executed once, or to loop repeatedly
throughout the scenario execution. For the looping to be allowed, the NMEA trajectory has to be
continuous
(see also: "Duration" on page 40).
From the NMEA stream, the GGA message and/or the RMC message are used to build the
trajectory (for detailed information on GGA and RMC, purchase the NMEA 0183 through
, meaning the first and last specified coordinates of the trajectory must be identical
relative
in relation to the start position and start time of the scenario, thus
nmea.org, or see, e.g. here). The trajectory can be described by one of these message types, or
(preferably) by using data where both message types are available.
If only one message type (GGA or RMC) is used, RMC is normally to be preferred over GGA.
However, the combination of both data formats is ideal: From RMC (NMEA ’s Recommended
Minimum), the timestamp along with longitude, latitude, speed over ground, and coarse will be
used to build a trajectory. RMC does not include altitude, hence if no GGA messages are
available, the altitude will be set to 0 meters.
The GGA message, on the other hand, contains no speed/coarse information, and if only GGA
messages are used (no RMC), the data rate should be 10Hz. Other data fields in the GGA
message are ignored.
Note that the NMEA trajectory file can become quite large in size when sampling rate is high and a
large distance is covered. Simulation files uploaded to the GSG unit cannot contain more than
12000epochs (~19minutes RMC+GGA at 10Hz). If scenarios with NMEA files with more than
12000 epochs are started, upon start of the scenario a dialog will provide you with the option to
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either
not
start the simulation, or to
specified NMEA file.
For an example on how to apply the NMEA message syntax, see Making a One-Line Trajectory.
truncate
the trajectory to only use first 12000 epochs from the
RSG Trajectories
Even if the RSG license option is
format and utilize these types of trajectories by up-loading the desired files onto your GSGunit.
The RSG format is further described under "RSG Command Reference" on page 232.
Note: As a user, you can log a trip using a standard GPS receiver and upload the
logged data to GSG-5/6 for repeated replays. It is, however, strongly recommended
to always use the StudioView program to test the logged data, as well as interpolate
and smooth it, so as to make sure it will work flawlessly in a simulation environment.
not
installed, you can still use the Spectracom-proprietary RSG
Note about trajectory movements
In general, please note that trajectories must at all times describe a movement that is realistic and
possible to perform in real life. Users are strongly recommended to prefer ‘smooth’ methods to
describe the movements. This means that acceleration and heading commands are to be preferred
over ‘hard’ changes, such as commands that set user coordinates or speed. When trajectories are
described through coordinate or (large) speed changes, the data must be provided in 10Hz format
and must not contain sudden changes in speed/directions.
In general, GNSS receivers are very sensitive to g-force and unrealistic user movements will result
in the receiver losing track of the simulated signals.
3.5.4.3 Timestamp Usage in Trajectories
GSG will transform the first timestamp in an NMEA trajectory in order to adapt it to the scenario
start time. All other timestamps in the NMEA trajectory are transformed accordingly, thus keeping
the relative position/times in the NMEA trajectory intact. Therefore, it is not necessary for the
scenario start time to match the NMEA time stamp.
A given NMEA trajectory can be replayed in any GPS time frame, utilizing any earth coordinates.
As of firmware version 3.0, Spectracom GSG units support 10Hz NMEA data.
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3.5.5 Ephemeris
The satellite constellations and the transmitted navigation data of each satellite are dynamically
built, once you start the scenario or the signal generation. The constellation and the navigation data
is based on RINEX data stored in the unit, or uploaded to the unit. The constellation orbits can be
refined by providing precise orbit information in SP3 format (for details, see below).
GPS and QZSS almanac data may optionally be provided in the form of YUMA files (for details,
see below).
In addition, SBAS message files are also supported (see "SBAS Satellites" on page 75 and "UserUploaded Ephemeris" on the next page below for more details).
Under the menu item Select > Select Scenario > Configure > Ephemeris, there are two or three
options to choose from (as described below), in order to select a source for your scenario
navigation data:
Default
Download
User-uploaded files.
3.5 "Select" Menu
Figure 3-6: Ephemeris selection
3.5.5.1 Default Ephemeris
The default RINEX data for GPS and GLONASS is based on the CDDIS GNSS archive, using
the brdc files. The non-redundant brdc file merges the individual site navigation files into one, and
thus can be used instead of the many individual navigation files.
This data is complemented by GLONASS almanac data downloaded from ftp://www.glonass-
iac.ru/MCC/ALMANAC/, covering the same period (file names are prefixed by receiver types,
e.g. MCCT_ , MCCJ_, GG-24, or TOPCOM_).
The default navigation data begins Jan 8, 2012 and runs for 33 consecutive days.
For Galileo, BeiDou, and IRNSS, the GSG unit comes shipped with its own ephemeris data set.
When the ephemeris setting is set to Default, the GSG unit builds all scenarios, any start date,
using the default data. If there is an exact match for the scenario Start time and preloaded
navigation files, that navigation data will be used. If an exact date match is not found, then the
GSG unit will use the first preloaded navigation data with the same day of the week as the
scenario’s start time. Further simulation days will use consecutive in date navigation data.
In general, the start time of the scenario always supersedes the time stamps in the navigation data
files. If file date and scenario start time do not match, then the loaded data is transformed
accordingly to match the scenario’s start time. If the scenario defines a GPS almanac files only,
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the YUMA files will define the almanac and the ephemeris will be derived from the default RINEX
data.
3.5.5.2 Download Ephemeris
The user can let the unit automatically download navigation data from official websites. The
navigation data, brdc files and GLONASS almanac files are retrieved from the same sites as
mentioned under "Default Ephemeris" on the previous page.
For this feature to work, the following requirements must be met:
1.
The GSG unit must have access to the Internet.
2.
The correct DNS address must specified, either by setting Options > Interfaces and
Reference > Network > Obtain IP autom. = Yes, or—when using a static IP
configuration—by manually entering the correct DNS address.
3.
The scenario start time must be in the past.
The downloaded navigation data will be locally stored on unit. On subsequent simulations the GSG
unit will first look for previously downloaded files before attempting to retrieve them again. Hence
once scenarios have run once they can also be replayed at later occasions even if the Internet
connection is no longer available.
Note, however, that the unit performs automatic clean-up of downloaded files and that this cleanup will occur when free disk space is less than 20% of the total disk space.
Download cannot be used in conjunction with Galileo, INRSS and/or BeiDou simulation. The
download functionality does not support the downloading of GPS almanac files.
Simulate Now
When Download ephemeris is used, it is also possible to simulate the
a.
the Simulate Now license option is installed, and
b.
the Start Time is set to NTP.
In this case, the navigation data will be based on hourly data retrieved from the official GPS
ephemeris site ftp://cddis.gsfc.nasa.gov/pub/gps/data/daily/.
Please note that this functionality is only available for GPS, and that the availability of the data
cannot be guaranteed.
3.5.5.3 User-Uploaded Ephemeris
User-specified RINEX and SP3 files can be uploaded to the unit. Multiple files may be selected.
The uploaded RINEX files will be used to build both constellation, and navigation data for the
satellites. If SP3 data is provided, it will override RINEX data for the definition of satellite orbits in
the constellation. If no SP3 data is available, the constellation orbits will be built, using provided or
built-in RINEX data.
current time
, provided:
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The number of RINEX files necessary depends on the scenario’s start time and duration, and must
be equal to the total number of simulation days (including start/end days utilizing less than
24hours).
In the event that dates for the user-specified data do not match the scenario’s start time, then GSG
will transform the start time in order to resolve the conflict.
If a satellite system (e.g., GPS, or Galileo) is selected (i.e., number of satellites selected is not 0)
and no navigation files are selected for that particular satellite system, then GSG will use default
data for that satellite system.
The RINEX format support includes version 2.x and 3.0.
The file extension for SP3 files must be *.sp3 (not case sensitive).
Downloading GPS RINEX files manually:
1.
Decide on the start date and time of the scenario, and the duration.
2.
Determine the number of files needed to cover the duration. (Each file contains up to
24hours of information, i.e. midnight to midnight.
3. Go to the website ftp://cddis.gsfc.nasa.gov/pub/gps/data/daily/ and select the required
year, and then the day of year.
4.
In the directory for that day of year, choose the XXn folder, where XX is the 2-digit year.
5.
In the XXn folder, select and download the file brdcYYY0.XXn.Z, where XX is the 2-digit
year and YYY is the 3-digit DOY value.
6.
Inside the zipped folder you download is the file to use in the unit.
7.
Repeat this procedure for each day you plan on simulating in your scenario.
YUMA
Optionally, GPS and QZSS almanac data may also be provided in the form of YUMA files, which
are identified by their .alm file extension. GPS and QZSS almanac files are identified by a firstletter file naming convention:
If the first letter of the file name is a ‘q’, GSG assumes the file contains QZSS satellite
almanac data.
If the first 2 letters are ‘qg’, then GSG assumes the file contains both GPS and QZSS
satellite almanac data.
If the first letter is anything other than ‘q’, GSG assumes the file contains only GPS
almanac data.
YUMA almanac data can be used with custom RINEX files, or default ephemeris data. If no
custom RINEX files are provided, the default data will be used.
This allows testing using GPS and QZSS satellites with the same, or different GPS almanac data.
The GSG supports multiple GPS and QZSS almanac files. The YUMA almanac is considered valid
for ±3.5days from the TOA value (Time-of-almanac) listed in the YUMA almanac.
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The scenario is restricted to start times within this range. If a scenario runs beyond this range of
time, no new satellites will be added. If the user specifies a start time outside this range, a dialog
will advise the user that the ephemeris and almanac are dates are mismatched. The SCPI error
“Data out of range" will be logged to indicate this issue for remote control users.
CNAV
You can also provide a file with CNAV messages to be used with GPS and QZSS L2C and L5.
The file extension is .cnt (CNAV train), and the file is satellite-specific. The file name conventions
are:
PRN<satid>_y<4digityear>_d<dayofyear>_h<hourofday>.cnt
e.g., PRNG01_y2013_d105_h14.cnt.
Each row of the file should contain:
satSys(A1), satid (I2), 1X, year (I2), 1X, month (I2),
1X, date (I2), 1X, hour (I2), 1X, min(I2), 1X, sec (I2),
1X, msgid (I2), 1X, [optional] hexmsg (A76)
E x a m p l e :
G01 13 04 15 14 00 00 11 8B04B4ED919863A6671F473A31412695EFF3C
026C0209FF07D601F775FEFE1FF987800000000
The hexmsg part is optional, and if not provided, it will be generated by GSG. This enables for
users to specify only the order of messages.
The messages are used in a circular manner, i.e. after the last message is sent, the first message
will be sent again. The starting message is selected based on scenario start time, i.e., it can be
one of the middle messages in case scenario starts later than the time of the first message.
Since the same file is used for L2C and L5 message trains which have different message duration,
only the timestamp of the first message is relevant to decide the starting message. The week
number and tow, as well as CRC, are recalculated by GSG.
SBAS
SBAS message files must follow the following file naming conventions so that GSG can recognize
them:
For EGNOS: PRN*.ems
For WAAS: Geo*
SBAS message files do not need to be transformed to the scenario date as all timing is relative, i.e.
a message file downloaded for a particular date can be used also with any other scenario start
date.
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ANTEX
You may also specify an ANTEX file to be used in simulation. The file extension is .atx. It
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contains satellite antenna phase center offsets and phase center variations. When present, this
information is used for improving satellite range calculation.
Note: For GLONASS, matching ephemeris and almanac files must be specified
(only the 2- line AGL format is supported, see ftp://ftp.glonass-
iac.ru/MCC/FORMAT/Format.agl). In addition, GLONASS almanac files must
be named *YYMMDD.agl (i.e., a date must be provided at the end of the file
name).
Note: The GLONASS data at this publicly available FTP site is known to contain
errors. These can cause the GSG to generate signals that are deemed ‘bad’ by a
receiver and may not be used in a fix or for navigation. This data is not maintained by
Spectracom and is not guaranteed.
Note: The GPS and QZSS almanac files specified must comply with the YUMA file
format and match the first 5 characters exactly for field identification. The spacing to
the rightmost column of data must be preserved. If the file fails to be processed,
verify that the Af0 and the Af1 lines do not contain a space between these prefixes
and the (s/s). For example, the line must be Af0(s/s), not Af0 (s/s).
Note: RINEX data files in most cases must be full day files. However, when GPS
almanac files are provided, the RINEX records can be of shorter duration. RINEX
files of less than a day duration without supporting GPS and QZSS YUMA almanac
files are limited to start times times only after 1400 hours, and may operate for
limited times.
3.5.6 Leap Second
To set a leap second, navigate to Select > [Select Scenario] > Configure [selected scenario]:
View2/3 > LS:.
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Figure 3-7: Leap second configuration
The leap second field can be set to -1, 0 or 1, and indicates a future change in the leap second
value. While the ΔtLSis set automatically based on information in the used ephemeris data, the
value given in the leap second field will impact values related to LSF (Leap Seconds Future).
If the leap second value is set to a value other than zero, the following values will be
used:
Δt
= ΔtLS+ value given in the leap second field
LSF
WN
June, or 31st of December, which-ever comes first with respect to the scenario start time.
DN = Day number of the date described above.
= The GPS week number (eight bit representation) of the week that includes the 30th of
LSF
If the leap second is set to zero, the following values will be used:
Δt
= Δt
LSF
WN
DN = 1
= WNLS– 1
LSF
LS
Considerations
Note that downloaded and default navigation data files do not contain any LSF information (RINEX
v2.1). Therefore it is still necessary to set the LSF when a leap second change will occur, in order
to ensure correct behavior. The default UTC/GPS offset currently is set to 17 seconds (see
Options > Interface and reference: Network > Network configuration: NTP server).
3.5.7 Event Data
Events can be used to introduce changes into a running scenario. Events can be used to change
the power levels of satellites, to control multipath settings, and to control navigation bits, e.g.
simulating bit errors in the navigation message. Events are captured in event files.
Each line of an event file describes one event, using one of the following formats:
1.
TIME {scenario | prn SATID | channel NUMBER} relpower
RELPOWER
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2.
TIME {scenario | prn SATID | channel NUMBER} abspower
on|off|ABSPOWER
3.
TIME {prn SATID | channel NUMBER} duplicate RELRANGE
RELDOPPLER RELPOWER EFFECTIVETIME [CHTARGET]
4.
TIME {prn SATID | channel NUMBER} multipath RELRANGE
RANGECHANGE RANTEINTERVAL RELDOPPLER DOPPLERCHANGE
DOPPLERINTERVAL RELPOWER POWERCHANGE POWERINTERVAL
[INSTANCE]
5.
TIME {prn SATID | channel NUMBER} delete [INSTANCE]
6.
TIME prn SATID navbits SIGTYPE SFID PAGEID STARTBITPOS
ENDBITPOS HEXSTRING REPEAT CRCFLAG PRINTFLAG
All formats begin with a time tag (TIME), which is the time of application for the event, measured
as seconds passed since the scenario Start Time. Events which apply to all satellites use the
scenario keyword. Events which apply to a specific satellite indicate this by specifying
channel NUMBER or prn SATID values.
The first format, relpower, defines a change in the power level for the scenario or a
satellite identified by SATID or channel number.
The second format, abspower, sets the absolute power for the scenario or a satellite
identified by SATID or channel number
The third format, duplicate, generates a duplicate signal from a given satellite, using
a specified delay, Doppler and power level. Duplicate channels require 60seconds to be
created, and are introduced at fixed 30-second intervals. Only 4 Duplicate satellites are
allowed to be created at a time. Duplicate events closer together than 4seconds are spread
apart automatically to maintain 4 second separation.
SBAS and Interference satellites cannot be duplicated. The optional CHTARGET
parameter specifies the channel to be used. If the channel is used by a satellite, this
satellite will be disabled, and the multipath satellite replaces it. If the CHTARGET
parameter is not specified, the multipath satellite will be created in the first unused channel.
Multipath, SBAS and interference/jamming channels cannot be duplicated.
The fourth format, multipath, modifies the multipath parameters of a satellite. If the
satellite is not a duplicate, it becomes a duplicate satellite, which is reflected in its SATID.
SBAS and interference/jamming channels cannot have their multipath parameters modified.
The fifth format, delete, deletes a satellite. If the satellite is not a multipath duplicate, it
will typically automatically re-appear after 1to2minutes. SBAS and interference/jamming
channels cannot be deleted.
The sixth format, navbits, sets bits in a navigation message. The ENDBITPOS-
STARTBITPOS+1 LSB of the HEXSTRING are used to replace the bits between
STARTBITPOS and ENDBITPOS, so that the ENDBITPOS is aligned with the LSB of
the HEXSTRING.
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Should ENDBITPOS- STARTBITPOS+1 > length (HEXSTRING ), the HEXSTRING
will be used as a repeating pattern to replace the bits between STARTBITPOS and
ENDBITPOS.
Multiple navbits events may be applied to the same message. Note that a navbits event is
applied to the first message from the event TIME with the SFID and PAGEID
specified in the event. For GPS the bit count starts with MSB , whereas for Glonass, the
count starts with LSB. Only GPS and GLONASS are currently supported.
The units for the event parameters are:
TIME in seconds since scenario start time
SATID is a satellite ID. The format explained in protocol documentation.
NUMBER is the channel number. Range depends on GSG model.
RELPOWER relative change in power settings specified in dB
ABSPOWER absolute value for power settings specified in dBm
RELRANGE is the relative range delay in meters.
RELDOPPLER is the relative Doppler offset in meters/sec.
EFFECTIVETIME numerical number. Reserved for future use.
CHTARGET is the channel number to where the duplicate is put. Range depends on GSG
model.
RANGECHANGE is the change in range over RANGEINTERVAL. Specified in meters.
RANGEINTERVAL is the time period in which the RANGECHANGE is updated.
Specified in seconds to the tenth of seconds accuracy.
DOPPLERCHANGE is the change of Doppler in meters/sec.
DOPPLERINTERVAL is the time period in which the DOPPLERCHANGE is updated.
Specified in seconds.
POWERCHANGE is the change in power over POWERINTERVAL. Specified in dB.
POWERINTERVAL is the time period in which the POWERCHANGE is updated.
Specified in seconds.
INSTANCE identifies which instance [1..8] of SATID we want to act on. If several
(duplicate) satellites exist with the same SATID, INSTANCE can be used to identify a
particular duplicate satellite.
SIGTYPE is one of the signal types supportedby the satellite. Allowed values are: L1CA,
GPSL1CA, L1P, GPSL1P, L1PY, GPSL1PY, L1CAP, GPSL1CAP, L1CAPY,
GPSL1CAPY, L2P, GPSL2P, L2PY, GPSL2PY, L2C, GPSL2C, L5, GPSL5, L1, GLOL1,
L2, GLOL2
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SFID is
a subframe ID (with GPSL1 and L2P signals)
a message type (with L2C and L5 signals)
a frame ID (with Glonass)
PAGEID is
a page ID (with GPSL1 and L2P signals)
0 (not relevant) when the subframe ID is 1-3
0 (not relevant) with L2C and L5 signals
a string idID (with Glonass).
STARTBITPOS, ENDBITPOS are positions of bits in a navigation message.
HEXSTRING is a bit pattern to be set in the message.
REPEAT
set to 0, if the modification should be applied only once
set to 1, if the modification should be repeated on every message.
CRCFLAG
set to 0, if CRC/parity is not to be corrected after the modification
set to 1, if CRC/parity needs to be corrected after the bit modification.
PRINTFLAG
set to 0, if the modified message does not to be logged (default)
set to 1, if the modified message needs to be logged in the execution log. Note that
the message is logged only once, even if the modification is repeated on every
message (repeat flag is 1).
PROPENV
See "Propagation Environment Models" on page 64.
An example event file containing all five formats with explanations is shown below:
1.0 channel 7 relpower -3
2.0 prn G32 abspower -110.5
3.0 scenario abspower off
4.0 scenario abspower on
5.0 scenario relpower 2
10.0 prn G9 duplicate 30.0 -0.01 -8.3 0
10.0 channel 6 duplicate 30.0 -0.01 -8.3 0
11.0 channel 6 multipath 35.0 0.01 1.0 0.0 0.0 0 -10.0 0.0 0
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11.0 prn G9D multipath 25.0 0.01 1.5 0.0 0.0 0 -15.0 0.0 0
12.0 prn G1 navbits L1CA 1 0 77 77 1 0 0
170.0 channel 6 delete
180.0 channel G9D delete
1.0 seconds into the scenario the power level of the satellite in channel 7 will be attenuated
by 3.0 dB.
At 2.0 seconds, the absolute power for GPS PRN 32 is set to to -110.5 dBm.
At 3.0 seconds, the signal transmissions for all satellites are turned off.
At 4.0 seconds, the power settings for all signals are restored.
5.0 seconds into the scenario, the power level of all satellites is increased by 2.0 dB.
At 10.0 seconds, a duplicate of the GPS PRN 9 satellite is created: The range of the
duplicate signal is delayed by 30.0 meters, it has a Doppler offset of -0.01 m/s and a power
level that is 8.3 dB lower than the original signal.
At 10.0 seconds, a duplicate of the satellite in channel 6 is created: The range of the
duplicate signal is delayed by 30.0 meters, it has a Doppler offset of -0.01 m/s and a power
level that is 8.3 dB lower than the original signal.
At 11.0 seconds, the multipath settings of the newly created duplicate, identified by its
channel number 6, is modified: The satellite will have a 35 meter range offset, increasing
with 1cm/s. It will have its power attenuated by 10 dB.
At 11.0 seconds, the multipath settings of the newly created duplicate, identified by its
SATID ‘G9D’, are modified: The satellite will have a 25 meter range offset, increasing with
1.5cm/s. It will have its power attenuated by 15 dB.
After 12.0 seconds, the MSB is set to 1 in 6-bit health (bits 77-82) in the first GPS L1CA
message with subframe ID 1 sent by satellite G1.
After 170.0 seconds the channel number 6 duplicate is deleted.
After 180.0 seconds the G9D duplicate is deleted.
Note: Several Events can occur at the same epoch. If so, any PRN/channel event
overrules scenario events, see example below.
E X A M P L E :
The output power of channel1 is set to -142.0 dBm, while all other channels are transmitted
with an output power of -147.0dBm.
4.0 scenario abspower -147.0
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4.0 channel 1 abspower -142.0
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Note also that abspower settings of events overrule the Transmit power setting specified
under Options > Transmit power, while observing the external attenuation settings.
Duplicating a satellite at time 00.00 is not permitted.
3.5.8 Antenna Settings
Several antenna-related settings can be configured to allow for optimal scenario simulation:
antenna gain pattern, lever arm, and elevation mask.
To configure these settings, navigate to: Select [Select Scenario] > Configure Scenario: View
2/3: Antenna.
3.5 "Select" Menu
3.5.8.1 Antenna model
The antenna gain pattern can be specified for each scenario, using a set of pre-defined antenna
models , or by utilizing a user-specified file. The built- in antenna models assume an omni-
directional gain pattern where the maximum gain is to be found towards the zenith.
The pre-defined antenna models are:
Zero model: Isotropic antenna with a gain of 0 dBic towards all directions. This is the
default.
Patch: Gain pattern approximates TOKO DAK Series patch antenna with maximum gain
+5 dBic. Size of the patch is 25 x 25 mm and ground plane 70 x 70 mm.
Helix: Gain pattern approximates Sarantel SL1200 (GeoHelix-P2) antenna pattern with
maximum gain -2.8 dBic. This is a small helix antenna designed to be embedded in
handheld devices e.g. mobile phones. See http://www.sarantel.com for details.
Cardioid: Gain pattern 1+sin (elevation) with maximum gain +3 dBic.
GPS-703-GGG: Gain pattern approximates Novatel’s GPS-703-GGG antenna with
maximum gain of +5.7 dBic. See www.novatel.com for details.
The format used to describe gain patterns is the FEKO pattern file format version 6.1, Far Field
format, File Format 2.0. Gain patterns for various frequencies are to be included in the same file as
separate Solution Blocks. The GSG units expect the result type to be either Gain or Directivity,
and enforces a maximum value of 50 for the No. of Theta/Phi Samples, with 36 as the
recommended choice yielding a 5/10 degree resolution on elevation/azimuth.
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The first line of the antenna file is expected to define the File Type. The GSG defines phi0
degrees, i.e. the x-axis of phi, to point towards the north direction.
3.5.8.2 Lever arm
A lever arm can be specified to separate the antenna position from the body mass center of the
vehicle: All trajectory movements in the simulation will act on the body mass center of the vehicle.
By default the antenna is located in this the body mass center position, pointing upward. To
specify that the receiver antenna is
be configured.
The lever arm settings specify the relative position change in the form of (x, y, z) along the body
axis of the vehicle frame, where the coordinate system XYZ is aligned with the body mass center
frame. At the start of a scenario, the X-axis corresponds to the east/west axes of the ENU frame
and the nose is pointing to the north.
The X-axis has a positive direction towards the right side of the sensor. The Y-axis has a positive
direction towards the front of the sensor. The Z-axis has a positive direction towards the top of the
sensor.
For more information on vehicle modeling, see "Environment models" on page 63.
not
located in the body mass center position, a lever arm can
3.5.8.3 Elevation mask
The elevation mask specifies how low GNSS satellites will be simulated. The elevation mask is
set to zero by default.
Figure 3-8: Elevation mask
A receiver typically has a higher elevation mask and it will not use any satellite below the elevation
angle of its set mask. The recommended setting is to set the elevation mask of GSG to a value
equal or less than that of the device under test.
In order to conserve channels by not generating signals the GNSS receiver will not use in its fix,
the elevation mask in the GSG can be set to a slightly higher value. This is especially important
with, e.g., GSG-52/53 Series units, or GSG-5 models equipped with 4-channels.
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3.5.9 Advanced Configuration Options
3.5.9.1 Multipath signals
A multipath signal is a GNSS signal bouncing off a reflective surface prior to reaching the GNSS
receiver antenna. Quite likely, this causes many of the same signals to arrive at the receiver at
different times. The receiver then needs to determine which of the signals are received directly.
3.5 "Select" Menu
Figure 3-9: Multipath signals in urban environment
To configure a multipath signal, navigate to Select > Select Scenario > Configure Scenario,
View 2/3: Advanced, and specify a number greater than zero for Multipath signals.
Note: Your GSG unit requires free channel(s) available, in order to allow for the
creation and configuration of a (several) new multipath signal(s).
Press enter to display the first configuration view for the first Multipath signal (the number of views
equals the number of signals you specified.)
Figure 3-10: Multipath signal configuration view
The following multipath parameters are configurable:
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Satellite
This specifies which satellite is to be duplicated by the multipath signal. The value specified
is a running number starting from 1 to the number of satellites defined to be in the scenario.
‘1’ would mean that we will duplicate the satellite in the first position when scenario starts.
Range
Offset: The Range (or: Code) offset in meters. For a multipath signal this value should
typically be positive, meaning that the travelled distance of the signal will be longer than
that of the original or line-of-sight (LOS) signal.
Change: Change in range offset, given in meters / Interval
Interval: Specify change interval in seconds to the nearest tenth second.
Doppler
Offset: The offset in Doppler in centimeters/seconds
Change: Change in Doppler offset, given in centimeters/seconds/Interval
Interval: Specifying change interval in seconds.
About Range Offset and Doppler
The code (range offset) and Doppler are connected 1-to-1 and cannot be controlled separately in a
conflicting manner. For example, a Range Change of 0.019m/s with Interval ‘1’ has the same
effect as specifying Doppler to 1.9cm/s and leaving all Change/Interval settings at 0.
When both code, and range, and possible change/intervals are specified, the cumulative effect of
all things specified will be simulated.
To simulate, e.g., a carrier phase offset that is static relative the LOS signal, please specify the
code offset (to, e.g., 0.095 meter) at start and set all Code and Doppler settings to zero.
Random CP
The carrier phase offset can also be randomized on startup by setting the ‘Multipath random CP” to
‘On’ in the GSG menu (or ‘RandomMpCP’ keyword in the configuration file).
Power
Offset: The offset in output Power in dB
Change: Change in Power offset, given in dB / Interval
Interval: Specifying change interval in seconds. If the interval is zero, the offsets will be set
at startup and remain static.
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Considerations:
SBAS and interference/jamming channels cannot be duplicated.
The Change/Interval effect will be interpolated. If the initial interval is zero, the offsets will
be set at startup and remain static.
In a multi-frequency constellation, the multipath configuration will apply to all active bands.
To match the multipath conditions as specified in the LTE/3GPPS A-GNSS test
specification, for GPS the following settings should be used:
Range Offset 150m
Doppler Offset 1.9 cm/s
Power Offset -6dB
Multipath random CP: ON.
Press the view key to configure the next multipath signal, when several multipath signals are
configured.
Press the exit key to save your multipath configuration.
3.5.9.2 Interference signals
Note: The Interference feature is only available with GSG-5, GSG-55, GSG-56 and
GSG- 6 Series products. Some features are only available when OPT-JAM is
enabled in the unit (see "GSG Series Model Variants and Options" on page 136).
Spectracom GSG-Series simulators can generate GNSS interference signals to test GNSS
receiver performance. To configure an interference signal, navigate to Select > Select Scenario >
Configure Scenario, View 2/3: Advanced: Interference Signals.
After specifying the desired number of interference signals (using the UP/DOWN arrow keys),
press enter to display the first interference signal configuration view (the total number of views
depends on how many interference signal you specified):
Figure 3-11: Interference configuration view
The following parameters can be configured:
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Signal type
Any signal type your GSG unit is licensed for can be configured (un-licensed signal types are
grayed out).
Figure 3-12: Interference signal type configuration view
The interference signal type can be:
GPS: L1CA, L1P, L2P, L1P(Y), L2P(Y), GPS carrier, SBAS
GLONASS: L1, L2 or GLONASS carrier
Galileo: E1, E5a, E5b or a Galileo carrier
BeiDou: B1,B2 or BeiDou B1,B2 carrier signal
QZSS: L1CA or QZSS L1 carrier signal.
If your GSG unit supports jamming simulations (OPT-JAM), sweep and narrowband noise
are available as interference types.
Mode in the lower right-hand corner allows to further manipulate the interference signal by offering
the following options:
Modulated: standard signal type (default)
PRN: Pseudo-Random Noise (see also Navipedia: GNSS signal for more information)
Unmodulated: carrier signal (carrier)
Sweep (OPT-JAM only): A dialog is shown asking for startOffset, endOffset, and Sweep-
Time.
Noise (OPT-JAM only): A dialog is shown asking for startOffset, endOffset and
SweepTime.
Offsets are used to specify the bandwidth and position of the sweep/noise related to the
selected signal frequencies. The range of offsets is ±40MHz, but can be less when the
scenario is executed since signals are not centered in the middle of a frequency band.
Note: Noise interference is not available if wide band noise is set to ON
under the Options > Transmit power menu.
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3.5 "Select" Menu
Satellite ID/Frequency slot
For GPS, SBAS, Galileo, GLONASS, BeiDou, IRNSS and QZSS signals, the Satellite ID must
be specified.
For GLONASS carrier signals the Frequency slot must be specified.
In some instances, this field is not applicable, and will be grayed out (e.g., GPS carrier).
Frequency offset
The frequency offset refers to nominal frequency of the selected signal/frequency slot.
Power, Position
It is possible to simulate a location-based jamming signal by specifying a position for it. Locationbased jamming simulation utilizes the jamming signal power, and position to calculate the
distance from the simulated position, applying the path loss formula given earlier in this document
(see "Signal Power Level Considerations" on page 22) to calculate the power of the received
jamming signal. As the scenario position moves closer to the location of the jamming transmitter,
the jamming power increases, and vice versa.
When configuring a location-based jamming source, the distance to the scenario start position and
the jamming coverage are shown, in order to assist you in designing a reasonable jamming test
configuration.
Figure 3-13: Configuring the position of a jamming source
Note that the jamming power can be set to +60dBm, whereas the maximum GSG power level is 65dBm.
Example
The figure below shows a configuration of a sweeper interference signal for the L1, L2 and L5
bands (OPT-JAM installed).
Figure 3-14: Configured sweeper signal
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3.5.9.3 Base station
This feature allows you to configure a Base station , as it is typically used for high-precision
positioning, e.g. in surveying applications: A receiver in a fixed and known position tracks the
same satellites the mobile receiver ("rover") does, and in real-time transmits corrective positioning
data to the receiver in the rover via a radio transmission stream.
The Base station feature can only be enabled with GSG 6-Series units that have the Real-Time
Kinematics Option installed (OPT-RTK, see "GSG Series Model Variants and Options" on page
136.)
To configure a "virtual" Base station, which supports the output of RTCM differential data to be
used as input by a rover receiver, navigate to Select > Select Scenario > Configure Scenario,
View 2/3: Advanced: Base Station.
Figure 3-15: Base station configured in Advanced submenu
Once you selected the On option for Base station , the configuration view will be displayed:
Configure the position of the base station and the RTCM messages to be output by it.
Figure 3-16: Base station configuration dialog
The following Base station settings can be reviewed/configured:
RTCM version
The RTCM SC-104 version currently supported is Ver. 3.2. This cannot be changed.
For more information on RTCM standards, see: www.navipedia.net/index.php/RTK_
Standards.
Message type
Message types 1002, 1004, 1006, 1010, 1012 and 1033 are supported.
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Latitude, Longitude, Altitude
Enter the base station coordinates, using latitude, longitude, and altitude. As with Start position
coordinates, the format key can be used to switch between different coordinate formats.
Once a scenario is running, and the base station has been activated, the SCPI command
SOUR:SCEN:RTCM? can be used to query the GSG for the latest RTCM messages (update
rate of 1Hz), as previously configured. The output will be a hexadecimal string.
3.5.9.4 Environment models
Environmental Models allow GSG to simulate signal obscuration. (This feature is supported as of
software versions 6.1 and higher).
Scenarios utilizing signal obscuration simulate the blocking of GNSS signals by objects placed
along the trajectory route. Typical use cases are the simulation of urban "canyons", tunnels, etc.
Environmental models in GSG simulators are supported through compressed keyhole markup
language files (kmz), popularized by Google Earth™. A simple way to create these files is by using
the 3D drawing tool SketchUp™, available from Trimble Navigation Limited: www.sketchup.com.
Two kinds of models can be configured in a scenario, Vehicle model and Environment model:
3.5 "Select" Menu
Environment model
An environment model is a 3D model of the environment, e.g., buildings, ground, etc. All
environment models used must have a geo-location added to them before they can be used for
simulation purposes.
Vehicle model
A vehicle model represents a 3D model of the vehicle. The vehicle model will move with the
simulated trajectory. The body center of a simulated vehicle will be in the origin position of the
model, and all trajectory movements defined in the simulation will act on the body center. The
vehicle model should be placed so that its nose points to the north.
The vehicle model will also follow any pitch/roll/yaw movements simulated, i.e. if the vehicle
model rolls by 90 degrees, half of the sky is likely to be blocked by the vehicle itself (depending on
vehicle model used).
The antenna position oftentimes is not in the same location as the vehicle body center position. In
the simulation, this can be adjusted by configuring the lever arm values (see "Lever arm" on page
56).
The antenna position can also be specified in the vehicle model file by adding a component named
RecAnt. In the event that both lever arm, and RecAnt are set, the receiver antenna position as set
in the Vehicle model takes precedence. The vehicle model does not need a geo-location.
If a satellite is blocked by an object from either environment or vehicle model, i.e. it is not visible by
the receiver antenna, its power will be set to OFF.
GSG can successfully handle vehicle models with up to 130 triangles. Models should be optimized
for a low polygon count. The triangle count is limited to a total of 300 for the combined environment
and vehicle models.
For additional information, see the Spectracom Technical Note Vehicle Modeling.
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Propagation Environment Models
Built-in signal propagation models can be used to simulate multipath propagation in rural, suburban and urban areas. Used propagation models are specified in ITU-R Recommendation
M.1225, “Guidelines for evaluation of radio transmission technologies for IMT-2000” (see Section
2.1.4 Parameters of the wideband models). The document is available on the ITUwebsite
(http://www.itu.int/rec/R-REC-M.1225/en).
The ITU model corresponds to a tapped-delay line structure with a fixed number of taps: 3 taps in
rural and sub-urban environments and 5 taps in an urban environment.
The first tap (i.e. the direct path) may be either Rice or Rayleigh fading, corresponding to LOS and
NLOS situations, respectively. The other taps are always Rayleigh fading.
The ITU model describes multipath propagation for a single satellite either in a LOS or NLOS
situation. Propagation environment model generates multipath taps for the entire satellite
constellation. Based on the satellite elevation angle, the satellites are divided into three zones, as
illustrated below:
Open Sky, Multipath Zone, Obstruction Zone
64
Figure 3-17: ITU multipath propagation model
Satellites above the Open Sky limit are not affected by multipath propagation.
Satellites in the Multipath Zone (elevation angle between Obstruction Limit and Open Sky Limit)
are considered LOS signals, but affected by multipath propagation. The ITU model for LOS
situation is used for these satellites.
For satellites in the Obstruction Zone (elevation angle below Obstruction Limit), the direct signal
path may be obstructed, e.g., by a building. This is modelled by giving a probability foran NLOS
situation. With the given probability, the simulator classifies satellites as NLOS and takes the ITU
model for the NLOS situation into use. The NLOS situation changes only when a satellite leaves
the Obstruction Zone.
Note that, in addition to the two elevation limits mentioned above, the Elevation mask setting
applies to the simulation as normally.
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Environment Open sky limit Obstruction limit NLOS probability
Rural 20° 15° 0.1
Suburban 40° 30° 0.2
Urban 60° 40° 0.3
3.5 "Select" Menu
The Propagation environment is defined by the environment type (open/rural/sub-urban/ urban)
and three parameters:
Open sky limit, Obstruction limit and NLOS probability.
Default values for the parameters in each environment type are given in the table below. The Open
environment type is the default, meaning that all satellites assume free-space propagation.
Table 3-1:
The Propagation environment model is taken into use by setting an event scenario
Propagation environment type parameters
propenv. If stated without parameters, the default parameter values given above will be used. In
this case the format of the even line is:
TIME scenario propenv {open|rural|suburban|urban}
Note: For more information on Event simulation, see "Event Data" on page 50.
Alternatively, parameter values can be provided in the format:
TIME scenario propenv {rural|suburban|urban} OPENSKYLIMIT
OBSTRUCTIONLIMIT NLOSPROBABILITY
Example
0.0 scenario propenv suburban
300.0 scenario propenv urban
600.0 scenario propenv urban 90.0 60.0 0.75
The example event file above will create a simulation starting from sub-urban environment (default
parameters). After five minutes the simulation changes to an urban environment (default
parameters) and after ten minutes to a highly obstructed urban environment where open sky
satellites do not exist (open sky limit at 90 degrees), and satellites below 60 degrees elevation are
likely to be NLOS (NLOS probability 0.75).
The Propagation environment model can be defined in the scenario configuration by using the
Scenario editor in StudioView.
The Propagation environment model can also be set by using the corresponding SCPI commands
(see "SOURce:SCENario:PROPenv" on page 186).
When using the Propagation environment model, note that:
It takes 1minute to create multipath taps during simulation. Therefore the time interval
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between switching the environment model should be more than one minute.
The Event scenario propenv must be stated without parameters, or alternatively
with all three parameters specified.
Valid ranges for the parameter values are:
OPENSKYLIMIT: 0.0 to 90.0 (degrees)
OBSTRUCTIONLIMIT: 0.0 to OPENSKYLIMIT (degrees)
NLOSPROBABILITY: 0.0 to 1.0
It is possible that all multipath taps cannot be created because of limited number of
channels available. The Tap number defines the precedence of tap creation (direct path
first, and then second tap etc.)
The maximum number of satellites to be simulated should be set to a fixed value. If any
satellite system is set to ‘Auto’, no new duplicate channel can be created while the scenario
is running.
The number of multipath signals should be set to zero. When using the Propagation
environment model, the simulator automatically assigns the multipath channels.
Fading satellite signals (i.e. all satellites below the Open sky limit) are indicated by the letter
‘F’ next to the satellite number in the satellite information display when the scenario is
running. Created multipath taps (taps 2 to 5) are indicated by letter ‘D’.
3.5.9.5 Atmospheric model
Atmospheric conditions have an effect on the propagation of GNSS signals, and as such can be an
error source. GSG allows for these effects to be simulated, by applying tropospheric and
ionospheric models to a scenario.
To configure these models, navigate to:
Select > [Select Scenario] > Configure scenario, View 2/3 > Advanced > Atmospheric
model.
Iono model
The GSG unit comes with built-in support for a model of the ionosphere. By default the used model
is a reverse model of the model described in IS- GPS- 200D, Section 20.3.3.5.2.5, called
Klobuchar.
The a0-3 and b0-3 parameters set in the default model are set by the used navigation data files.
When set to Off, no delays caused by the ionosphere are used in the simulation.
Under normal testing conditions, the Klobuchar ionosphere model should be used.
66
Note: The GSG also supports simulation of ionosphere delays using files in the
IONEX format.
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Tropo model
A number of tropospheric models are supported by the device. These are:
Saastamoinen model. The model is based on Saastamoinen, J., 'Atmospheric Correction
for the Troposphere and Stratosphere in Radio Ranging of Satellites,' The Use of Artificial
Satellites for Geodesy, Geophysics Monograph Series, Vol. 15., American Geophysical
Union, 1972
Black model. The model is based on Black H., ‘An Easily Implemented Algorithm for the
Tropospheric Range Correction’, JOURNAL OF GEOPHYSICAL RESEARCH, 1978
Goad&Goodman, a tropospheric model based on Goad and Goodman(1974), "A Modified
Hopfield Tropospheric Refraction Correction Model", 1974
STANAG model. The model is based on NATO Standardization Agreement (STANAG)
Doc. 4294, Appendix 6.
The tropospheric model can also be set to Off, and no troposperic delays are used in simulation.
Under normal testing conditions, one of the tropospheric model
The tropospheric model also allows for the temperature, pressure and humidity to be configured:
should
be used.
Temperature: to be specified in degrees Celsius
Atmospheric pressure: in millibars
Humidity: relative humidity in percent.
The graph below illustrates the delays for the different models available, using default values for
environmental conditions.
Note that the troposheric delay added to satellites with low elevation angles are ‘capped’ at a
maximum value. The capping delay value and the elevation angle are a function of the model used.
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Figure 3-18: Tropospheric delay vs. elevation angle
3.5.10 Satellite Configuration
Depending on the model and configuration of your GSG unit, and the scenario chosen, several
satellite systems can be simulated in a scenario, each of which you may want to configure in
accordance with the requirements for your receiver-under-test.
The illustration below shows the configuration of GPS-based satellites as an example:
Figure 3-19: GPS satellite configuration
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To access the first satellite configuration view, navigate to Select > [Select scenario] >
Configure scenario: View 3/3.
The following satellite-relevant settings can be configured:
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Satellite System, e.g., GPS, Glonass (see "Satellite Systems" below)
Number of satellites simulated for a given satellite system (see "Number of Satellites"
below)
Signal Type, e.g., L1, L2 (see "Frequency Bands and Signal De-/Activation" on the next
page)
Satellite Constellation [GPS: "block"] (see "Satellite Constellations" on page 72)
Encryption (see "Encryption" on page 74)
SBAS/Augmentation (see "SBAS Satellites" on page 75)
3.5.10.1 Satellite Systems
The following navigation satellite systems can be simulated by GSG- series constellation
simulators, depending on unit configuration, see also "GSG Series Model Variants and Options" on
page 136:
GPS
USA; globally operating system, very accurate, regular modernization and upgrading
3.5 "Select" Menu
GLONASS
Russia; globally operating system, works independently from US military controlled
system; combination of Glonsass + GPS solves "urban canyon" problem
GALILEO
Europe; globally operating system; yet, not fully operational as of summer
2015;high-quality signals, multiple uses
BEIDOU
China; regional system (Asia); planned global expansion; open system
QZSS
Japan; regional system
IRNSS
India; regional system
3.5.10.2 Number of Satellites
The maximum number of satellites to be simulated by GSG in a given scenario is specified
separately for each available GNSS system. (For SBAS, see "SBAS Satellites" on page 75).
To edit the number of satellites for a GNSS system, navigate to: Select > [Select Scenario ] >
Configure Scenario : View3/3 > [Satellite System ]: Enter a number"Number of Satellites"
above
The theoretical maximum number of satellites that can be simulated is 64, but this number also
depends on:
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Constellation
Frequency Bands
1 2 3 4
GPS
L1 L2/L2C L5
Glonass
L1 L2
Galileo
E1 E5 E6
BeiDou
B1 B2 B3
3.5 "Select" Menu
The license and GSG model used (number of available channels)
How many frequency bands are used, e.g., if 64 channels are available, 64GNSS L1
satellite signals can be simulated, or, e.g., 32L1/L2 satellite signals. (Note that GPS L2 and
L2C are using separate channels, as are the Galileo bands E5a and E5b.)
The default setting is Auto, i.e. GSG will determine the number of satellites simulated at any given
time during scenario execution.
Note: If GSG runs out of free channels when in Auto mode, not all satellites will be
simulated.
3.5.10.3 Frequency Bands and Signal De-/Activation
When testing GNSS receivers, it is oftentimes required to test for multi- frequency, multiconstellation performance. All of the four major GNSS systems, i.e. GPS, Glonass, Galileo, and
BeiDou, transmit numerous signals across several frequencies, but through international
cooperation, these frequency bands have been coordinated:
The RF signals transmitted from satellites of different constellation systems…
… are transmitted on frequencies close to each other, yet they do not interfere with each
other
… can be decoded by one receiver (if supported by the receiver manufacturer)
… can be grouped into four main bands.
These four frequency bands are:
For multi-frequency, multi-constellation testing it is suggested to test any of the constellations,
frequency bands, or any combinationtogether.
The following frequency bands can be generated (GSG-configuration dependent):
For GPS:
L1CA
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L1P
L2P
L2C
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L5
P(Y): Pseudo encryption
For Glonass:
L1
L2
For Galileo:
E1
E5A
E5B
For BeiDou:
B1
3.5 "Select" Menu
B2
For QZSS:
C/A
SAIF
L2C
L5
De-/Activating Signals
Frequency bands can be turned ON/OFF separately, so as to configure which types of RF signals
specific to each supported satellite system shall be active/inactive when a scenario is running.
Depending on the configuration of your GSG unit, all of the frequency bands listed above can be
turned ON/OFF.
To turn ON/OFF a signal band, navigate to: Select > [Select Scenario] > Configure Scenario :
View3/3 > [Satellite System]: Enter a number of satellites > 1 (see "Number of Satellites" on
page 69).
The satellite constellation (see "Satellite Constellations" on the next page) must be configured
accordingly, in order to allow for, e.g., the L2C band to be simulated. In other words, if you chose to
disable satellites that can generate this signal, it will not be generated, even if you activate the
signal. Hence, it is recommended to leave all signal types ON (default), thereby letting the
configured satellite type determine which RF signals are active.
Use cases for turning OFF the transmission of individual frequency bands are:
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simulating a one-band antenna
reserving the maximum number of channels for other requirements (e.g., L1-only
transmission)
Considerations:
Altering active RF signals will not alter the navigation message. Hence from a receiver
point of view, choosing to de-active L2 and L5 will mimic the situation of using a single band
(L1) antenna.
Settings are GNSS-specific, not satellite-specific.
For GLONASS, C/A code is always used.
3.5.10.4 Satellite Constellations
Once existing GNSS satellites of a satellite system in orbit are being replaced by new, more
modern satellite types, the satellites are often categorized by their generation , or historic
constellation . In the case of the GPS system, these constellations are named by their block
numbers, e.g., "IIA".
Note: The functionality described below only applies to GPS and Glonass. Other
installed satellite systems, such as Galileo, still have their first generation of
satellites in orbit.
GSG offers 3 options to configure satellite constellations:
1.
The Default setting refers to the constellation state for April 22, 2015.
2.
Constellation-wide setting of the satellite generation, e.g., by setting all GPS satellites to
Block IIR-M:
Figure 3-20: Assigning one constellation block to all satellites
To access this configuration view, navigate to: Select > [Select Scenario ] > Configure
Scenario: View3/3 > [Satellite System]: Enter a number of satellites > 1 or Auto (see
"Number of Satellites" on page 69 View 2/2.
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Note: The G## numbers refer to the individual GPS satellites (Glonass
satellites are named R##).
3.
Explicitly specify the constellation for each individual satellite, using GSG StudioView:
Figure 3-21: GPS Constellation configuration (StudioView)
This functionality may be required for the configuration of scenarios taking place in the past,
or 'What-if' scenarios.
Consider the following when configuring satellite constellations:
The selected satellite constellation will impact the navigation message to mimic the type
of simulated satellite.
The satellite type will also impact the types of RF signals generated (see "Frequency
Bands and Signal De-/Activation" on page 70), i.e. for the signal type L2C to be
transmitted, the satellite type must be Block IIR-M (or higher), for L5 to be transmitted, the
satellite type must be of type Block IIF (or higher), etc.
Possible settings are:
For GPS:
II
IIA
IIR
Block IIR-M
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For Glonass:
3.5.10.5 Encryption
Next to the unencrypted L1 band Coarse/Acquisition Pseudo-Random Noise (C/A PRN code), the
Precise (P), but encrypted Pseudo Random Noise code is used to modulate both the L1, and the
L2 carriers.
While GSG cannot replicate the encryption, it can emulate, and thus represent the P(Y) code, so
as to allow for commercial GPS surveying receivers to be tested for their ability to derive the carrier
in a codeless fashion.
Note that this technology does NOT use controlled encryption. Instead, it mimics the encryption
so as to provide an RF signal in the L1/L2 P(Y) location.
IIF
(default)
Glonass-K1
Glonass-M
(default)
Note: GPS receivers that use genuine encryption methods will NOT be able to use
the L1/L2 P with Pseudo P(Y) code enabled because the encryption used is not as
expected and they cannot decode it.
To turn P(Y) ON/OFF:
1.
Navigate to: Select > [Select Scenario] > Configure Scenario: View3/3."Number of
Satellites" on page 69
2.
"Number of Satellites" on page 69
3.
"Number of Satellites" on page 69
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Figure 3-22: Turning pseudo encryption ON/OFF
4.
Navigate to the P(Y) entry at the bottom of the view, and select On, or Off.
Considerations:
For most L1/L2 GPS receivers, there are two valid configuration modes:
1.
Enable L1 C/A, L1P, and L2P only:
The L1P and L2P will be transmitted without encryption.
2.
Enable L1 C/A, L1P, and L2P, and Pseudo P(Y):
The P code will be scrambled to mimic a realistic P(Y) signal for use in receivers
that can make use of L1/L2 P(Y) signals for codeless applications, or to provide a
signal in the band to better emulate the real world.
In the GSG-6 series, the NAV message transmitted by the GPS satellites is
updated to reflect if (pseudo-) encryption is active or not. This is specified by bit19 in
the second word of subframe one. This bit represents the anti-spoof (A-S) flag,
where “1” indicates that the A-S mode is on in that satellite. It is recommended to
enable Pseudo P(Y) when the GSG-unit supports it. This will set the A-S flag to ON
which is required in some receivers. GPS receivers may reject L1CA code if the A-S
flag is off.
3.5 "Select" Menu
In GSG-5x units, where it is not possible to transmit Pseudo P(Y), the A-S bit is
always set to ON to indicate that encryption is on (although the actual RF signal is
not transmitted on such units).
The NAV message also holds information on the type of L2 signal being transmitted
(bits 11 and 12 of word three in subframe one). These bits are always set to indicate
that the P code is active on L2.
3.5.10.6 SBAS Satellites
Several GNSS augmentation systems, e.g.,differential GPS, exist to further improve positioning,
navigation, and timing functionality (see also: www.gps.gov). Space Based Augmentation
Systems (SBAS) incorporate system components such as additional SBAS geo satellites, ground
reference stations, and user equipment which together aid the GPS system, thereby allowing
greater precision and integrity, among other things.
SBAS systems support specific GNSS systems, are available for civil use, and have been/are
being developed for all of the GNSSsystems worldwide:
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Figure 3-23: GNSS SBAS systems
GSG can simulate SBAS satellites. Each scenario defines the number of SBAS satellites that
should be simulated. There can be 0, 1, 2, or 3 SBAS satellites per scenario.
To review/edit the number of SBAS satellites for the scenario chosen, navigate to: Select >
[Select Scenario] > Configure Scenario: View3/3"Number of Satellites" on page 69
The GSG unit will select SBAS space vehicles based on their elevation relative to the user
position. When the scenario is running, the SBAS satellite positions and speed will be updated
with the information found in the SBAS messages. These messages comprise different Message
Types, one of which—MT9—is used to update the satellite’s position and speed.
The SBAS satellites transmit their signals utilizing Coarse/Acquisition Pseudo-Random Noise
(see also "Encryption" on page 74). PRN numbers , which have been internationally coordinated,
have been allocated to each of the SBAS constallations. Although PRN120 … PRN158 are all
reserved for SBAS systems, only a few of them are actually used by satellites.
When determining the elevation angle of SBAS satellites, the GSG unit looks for the SBAS
satellites listed below. This is in contrast to the signal generator mode (see "Signal Generator" on
page 83) where the user can specify any SBAS PRNs to be simulated.
The currently supported SBAS satellites are:
EGNOS: 120, 124, and 126
WAAS: 133, 135, and 138
MSAS: 129, 137
GAGAN: 127, 128
The simulator uses two approaches for SBAS messages:
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Default SBAS messages (MT63)
EGNOS/WAAS message files
The default SBAS messages are always available. These messages should be recognized by
SBAS-compatible receivers. However, they carry no information and will therefore not enable the
receiver to correct GPS signals.
SBAS message files for both EGNOS, and WAAS are supported. EGNOS files (.ems) are ASCII
and hourly, while WAAS files are typically in binary format and cover a whole day. Both systems
share the same format of the messages. For details, see www.navipedia.net.
When the scenario has the Ephemeris set to Download, the GSG unit will download the SBAS
messages from official sites and match these messages to the time of the scenario. The SBAS
messages broadcast by these satellites are downloaded automatically from the following public
FTP sites:
EGNOS: ftp://131.176.49.48
WAAS: ftp://ftp.nstb.tc.faa.gov
MSAS: default MT63
GAGAN: default MT63
GSG logs into these sites anonymously. However, note that both FTP sites are likely to track and
record all FTP access, including access by GSG simulators.
The SBAS download starts when the constellation simulation of the scenario has started; not
during initialization of the scenario.
Considerations
If a scenario needs SBAS messages that cannot be downloaded from these FTP sites, the
scenario continues, but the GSG unit transmits null-messages (SBAS message type: MT63). An
SBAS-compatible receiver should still be capable of seeing the SBAS signals, but it will not find
any useful information (range corrections, time offsets, etc.) in these messages.
Because of these reasons, SBAS scenarios run best with a live Internet connection. Furthermore,
since the aforementioned FTP sites store only a limited amount of SBAS records, the start time of
SBAS scenarios has to be chosen carefully:
Usually, SBAS records that are less than a year (EGNOS)/6months (WAAS) old, can be found on
the FTP sites mentioned above. Therefore, it is advisable to select a start time that is not older
than one year for EGNOS scenarios, and not older than 6months for WAAS scenarios.
Moreover, the start time shall not be too close to the current time. For EGNOS, there can be a oneday delay before the SBAS messages are published on the FTP site. For WAAS the delay can
possibly be longer (up to 3or 4days).
An Internet connection is not
data will be locally stored on the unit, once they have been downloaded. Hence, the next time the
same scenario runs, the ephemeris data and SBAS messages are read from the local storage, not
from the online ftp sites.
GSG will performs automatic clean-up of downloaded files, once the remaining free disc space
falls below 20% of the total disc space.
always
needed, however: All downloaded ephemeris data and SBAS
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It is also possible to download the EGNOS and WAAS files from the ftpservers, and select them
for use in the scenario: The filename holds the information on the applicable time & date, which is
NOT available in the content of the file (all time is relative), and must follow these naming
conventions:
Should the files downloaded from the ftp server do not meet these format requirements, it will be
necessary to rename the files accordingly.
Note: The SBAS corrections are ‘applied backwards’ to the output GPS signals by
adjusting the signal ranges.
For EGNOS: PRN<prn>_y<YYYY>_d<doy>_h<hour>.ems
For WAAS: Geo<prn>_<GPSWeek>_<dayOfWeek>
Note: WAAS files do not have a file extension.
QZSS L1 SAIF
The QZSS satellites transmit also a SBAS signal, called L1 SAIF. The GSG unit can emulate this
signal. The signal is enabled by setting the value of “QZSSL1SAIF” to ”1” in a scenario file.
If the user does not specify a file containing the messages for transmission, the unit will transmit
only the default (MT63) messages. The naming convention for the transmitted files is the same as
for the WAAS satellites above. The PRN numbers reserved for QZSS L1 SAIF transmission start
from 183, so the name of the message file for J01 should start with “Geo183_”, for J02 with
“Geo184_”, etc.
For the best results, the user should specify the Rinex navigation file(s) used in the scenario,
together with the SAIF message files. This way the user can ensure that the simulated satellite
position based on Rinex NAV files is in line with the position information transmitted in the L1 SAIF
messages.
3.6 "Options" Menu
Features and functions that are not directly related to the scenarios are typically found under the
Options Menu.
3.6.1 Transmit Power
78
The term Transmit Power refers to the power transmitted by GSG during the execution of the
currently chosen scenario.
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Caution: To learn more about signal level compliance in the United States, see
"Signal Power Level Considerations" on page 22. If you live in other countries, check
your local emission standards.
The transmit power is specified in dBm.
The supported range is: Max. -65dBm … min. -160dBm.
The resolution is: 0.1dBm.
Default setting: -125.0dBm.
Note: The External Attenuation setting decreases the set Transmit Power
level.
Note: When the power settings of individual channels during scenario
execution (via the > Events menu, or protocol) the power range will be further
limited so that the maximum difference between the strongest and the
weakest signal is never more than 72dB.
To access the Transmit Power view, navigate to Options > Transmit Power . This view also
allows you to adjust the external attenuation (see "External Attenuation" on the next page), and
noise (see "Noise Generation" on page 81).
Figure 3-24: Configuring transmit power
Antenna cable length
The recommended Transmit power setting , assuming relatively short cables and that no
external attenuators are used, is - 125.0dBm. If long cables are used, it is recommended that
these are simulated by adjusting the external attenuation (see also "External Attenuation" on the
next page).
The Transmit Power set in the Options menu is assigned to the signal type with the highest power
level, and all others are set relative to that.
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Constellation Signal Power offset, dB
GPS
L1 C/A 0.0
L1 P -3.0
L2 P -3.0
L2C 0.0
L5 +1.5
GLONASS
L1 -2.5
L2 -8.5
GALILEO
E1 +1.5
E5a +3.5
E5b +3.5
BEIDOU
B1 -4.5
B2 -4.5
QZSS
L1 C/A 0.0
L1 SAIF -2.5
3.6 "Options" Menu
Considerations
A common problem is that signals too strong or too weak are used. A signal too strong will typically
‘jam’ the receiver, causing it to erroneously find many shadow signals. It is recommended that you
familiarize yourself with the typical signal/noise values for real satellites, and try to obtain similar
values when using this unit. When the signal strength is correctly set, the receiver will respond
directly and logically to changes in signal power.
The following table shows the offsets when referencing GPSL1C/A as zero dB offset:
Table 3-2:
Transmit power offsets
3.6.1.1 External Attenuation
External attenuation allows you to specify attenuation between the GSG power output, and the
receiving device. This allows the unit to compensate, e.g., for antenna cable lengths. Any of the
power settings (Transmit power, Event settings) will observe the specified external attenuation.
The range is: 0 … 30.0dB
Resolution: 0.1dB.
To adjust External Attenuation, navigate to Options > Transmit Power.
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3.6.1.2 Noise Generation
GSG-5/6 has the capability to simulate noise on the GPSL1 band. Noise simulation can be a
powerful tool for receiver testing, since it allows for a strong signal to be submitted, without
jamming the receiver.
To access the Transmit Power view, which—among other things— allows to adjust the noise
settings, navigate to Options > Transmit Power:
Figure 3-25: Adjusting noise settings in the Transmit Power view
Noise generation (GSG-5, GSG-56 and GSG-6)
The noise generated by GSG-5, GSG-56 and GSG-6 is similar to the noise of GSG-55, but differs
in so that the noise bandwidth is constant and set to cover both the GPS L1 as well as the
GLONASS L1 band. The noise central frequency is not configurable.
3.6 "Options" Menu
Noise-related adjustable parameters
Simulate Noise: Yes/No (Default: Yes)
C/N
: Carrier-to-noise density. Range: 0 … 56 dB-Hz
O
General considerations
International regulations keep the L1 band practically clean from disturbing signals, so the only
noise source is the natural background noise, as expressed in the following equation:
PN= kTB
Where k is the Bolzmann’s constant, T is the ambient temperature (in Kelvin), and BN is the
bandwidth (in Hertz).
For example, an ideal GPS L1 C/A code filter would have a passband of 2MHz, and noise power
passed by the filter at a temperature of 290K would be equal to -141dBm.
The ambient noise power spectral density is given by the equation:
NT= kT = 4.00 x 10
By definition, carrier-to-noise density is the carrier power divided by the noise power spectral
density. The GPS ICD specifies that the received signal level at the surface level is -130 dBm or
better. Carrier-to-noise density is then:
C/N0= -130 dBm/(-174 dBm/Hz) = 44 dB Hz
N
-21
W/Hz = -204 dBW/Hz = -174 dBm/Hz
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C/N0(not SNR) is the figure that the receivers typically display as an indication of quality for the
received, digitally modulated signal. If the receiver has bandwidth of 6MHz, SNR would be:
If a stronger input signal for the receiver is required, while maintaining the same C/N0, additional
noise needs to be introduced into the transmitted signal. One may think of this as having an active
antenna at the receiver input. The signal level is higher, but so is the noise level.
Interaction of Transmit Power and External Attenuation
When you change the values in the Transmit Power dialog, you may notice that other settings may
change as a consequence of the changes made. For example, if you have Transmit Power set to 70 dBm, and External Attenuation set to 5.0 dB, the unit actually transmits signals at -65dBm to
compensate for the external losses.
Note, however, that manually adjusting the attenuation to 10dB in such a situation will cause the
Transmit Power to drop to -75 dBm as a consequence. This is a result of the hardware
configuration, as the unit cannot deliver more than a total of -65 dBm. The Transmit Power setting
gives the power level at the end of your antenna cable.
SNR = 44 dBHz/(6 x 106Hz) = 44 – (10 x log10(6 x 106))dB = -23.8dB.
Adjusting Transmit Power: Best practices
In general, when changing the Transmit Power setting, it is recommendedto follow this order:
1.
Set the External Attenuation
2.
Set the Transmit Power
3.
Set the Noise Bandwidth
4.
Set the Carrier-to-Noise Density
5.
Set the Noise Offset (this can be done at any time without affecting the other settings)
Adjusting Power/Noise via SCPI command
If you use the SCPI protocol to change the power/noise settings, use the order above to do
modifications, and check the SCPI error after each command. If there is a Parameter Conflict
error, it would indicate that the unit accepted your command, but due to a conflict with a different
parameter, your parameter value was modified.
The conditions under which a Parameter Conflict may occur include the following:
1.
A Transmit Power value has been requested that is too high. The requested Transmit
Power is within the specified limits, but the External Attenuation setting limits the maximum
power to below the requested setting. Transmit Power is set to the maximum available,
rather than the value requested by the user. Increasing the Transmit Power may lead to an
increase of C/N0, as described under bullet #3 below. To prevent this from happening,
especially when using the SCPI protocol for making adjustments, always use the
command order described above, and check the SCPI errors after each command.
82
2.
An Unachievable Carrier-to-Noise ratio has been requested. The requested value is
within specifications, but the Transmit Power setting is too low to achieve the required
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setting. In this case, the ambient noise power spectral density limits the achievable carrierto-noise ratio. The Carrier-to-Noise density will be set to its maximum value, not to the
value requested by the user. The noise generator does not generate any additive noise in
this situation. Increase the Transmit Power, then set C/N0again.
3.
A Carrier-to-Noise ratio has been requested that is too low. The requested value is
within specifications, but the Transmit Power setting is too high to achieve the required
setting. The signal/noise generator does not have the capability to generate a noise signal
this strong (remember that noise power is more than the signal power – SNR is negative).
The Carrier-to-Noise density will be set to its minimum value, not to the value requested by
the user. Decrease the Transmit Power to decrease the required noise power.
4.
A Noise Bandwidth value has been requested that is too wide. (SCPI command only)
In effect, this leads to the same situation described under bullet # 3 above. GSG accepts
the noise bandwidth setting, but increases the C/N0to its minimum value. The noise
bandwidth required depends on the filters of the receiver. You have to search for the value
that is wide enough for your receiver. Set up a relatively strong signal (for example: -100
dBm, C/N044 dB-Hz), and narrow noise bandwidth. Then increase the noise bandwidth
until the C/N0value shown by your receiver stabilizes. It is a good idea to use the
narrowest bandwidth needed.
Note: The receivers use different methods to calculate C/N
the value given by the receiver may be different from the C/N0setting of the
GSG unit.
3.6.2 Signal Generator
Every GSG model can be operated as a signal generator, i.e. to generate one, or—if so equipped—
several satellite signals (with no Doppler), or one carrier frequency.
In Signal Generator mode, advanced GSG units can support: GPS, GLONASS, Galileo, BeiDou,
SBAS. If equipped with the L2 and/or L5 options, GSG allows the selected satellite(s) to transmit
all signals enabled on that satellite.
Note: For more information on available GSG models and options, see "GSG Series
Model Variants and Options" on page 136.
To configure the Signal Generator mode, navigate to Options > Signal Generator:
(or SNR), so
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Figure 3-26: Signal Generator configuration view (depends on licensing options installed)
The following Signal Generator options can be configured:
3.6.2.1 Signal type
The Signal type selection will open a new view, as shown below. Note that the view depends on
the licensing options installed on your unit.
Figure 3-27: Signal types configuration view
Combining signals from different GNSS systems
If your GSG unit is licensed for multiple channel operation, in Signal Generator mode it is not only
possible to choose between multiple frequency bands and codes, but also to simulate several
GNSS signals, e.g., both GPS and GLONASS, at the same time. This can be achieved by
enabling several GNSS systems from the Configure signal types menu.
In Signal Generator mode, GSG offers the following Signal type configuration options:
GNSS systems currently supported are: GPS, Glonass, Galileo, BeiDou, and QZSS, and
their corresponding signal types. For information on signal types, see also "Frequency
Bands and Signal De-/Activation" on page 70.
Pseudo-encryption (P(Y)): For more information, see "Encryption" on page 74.
SBAS Signals: It is possible to generate a signal for any of the SBAS PRNs. However,
GSG can generate a real SBAS message stream only if the chosen PRN corresponds to a
live SBAS satellite (see "SBAS Satellites" on page 75 for further details).
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