gr-mcp-docs/reference/cospas-sarsat/t-series/t013.md

---
title: "T013: Cospas-Sarsat Geosar Space Segment Commissioning Standard C"
description: "Official Cospas-Sarsat T-series document T013"
sidebar:
  badge:
    text: "T"
    variant: "note"
# Extended Cospas-Sarsat metadata
documentId: "T013"
series: "T"
seriesName: "Technical"
documentType: "specification"
isLatest: true
issue: 1
revision: 3
documentDate: "March 2021"
originalTitle: "Cospas-Sarsat Geosar Space Segment"
---

> **📋 Document Information**
>
> **Series:** T-Series (Technical)
> **Version:** Issue 1 - Revision 3
> **Date:** March 2021
> **Source:** [Cospas-Sarsat Official Documents](https://www.cospas-sarsat.int/en/documents-pro/system-documents)

---

# T013 - T013-MAR-26-2021.pdf

**Pages:** 38

---


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
 
COSPAS-SARSAT GEOSAR SPACE SEGMENT 
COMMISSIONING STANDARD 
 
 
C/S T.013 
Issue 1 - Revision 3 


COSPAS-SARSAT GEOSAR SPACE SEGMENT 
COMMISSIONING STANDARD 
 
 
 
 
History 
 
 
Issue Revision 
Date 
 
Revised Page(s) 
 
Comments 

Oct 2001 
 
 
 
 
Approved by CSC-27 


Oct 2012 
 
 
 
 
Approved by CSC-49 


Oct 2013 
 
 
 
 
Approved by CSC-51 


Mar 2021 
 
 
 
 
Approved by CSC-64 
 

TABLE OF CONTENTS 
 
 
Page 
 
 
1. 
INTRODUCTION .................................................................................................. 1-1 
 
1.1 
Purpose ....................................................................................................... 1-1 
 
1.2 
Scope .......................................................................................................... 1-1 
 
1.3 
Reference Documents ................................................................................. 1-2 
 
1.4 
Common System Units ............................................................................... 1-3 
 
2. 
ON-ORBIT SPACE SEGMENT TESTING AND COMMISSIONING ........... 2-1 
 
2.1 
Initial On-orbit Tests .................................................................................. 2-1 
 
2.2 
Commissioning Procedure .......................................................................... 2-2 
 
2.3 
Satellite System Data .................................................................................. 2-3 
 
2.4 
Periodic Tests ............................................................................................. 2-3 
 
2.5 
Routine Monitoring of the Space Segment................................................. 2-3 
 
2.6 
De-commissioning Procedure..................................................................... 2-4 
 
2.7 
Space Segment Status Reporting Procedures ............................................. 2-6 
 
 
LIST OF FIGURES 
 
Figure 
Page 
 
1.1 
GEOSAR Space Segment Interfaces ........................................................................ 1-2 
2.1 
GEOSAR Payload Commissioning Procedure ......................................................... 2-5 
2.2 
GEOSAR Problem Reporting and Investigation Procedures ................................... 2-7 
 
 
LIST OF TABLES 
 
Table 
Page 
 
B.1 
List of Post Launch Tests ........................................................................................ B-1 
C.1 
GOES Space Segment Assessment Indicators/Compliance Levels ........................ C-1 
C.2 
INSAT Space Segment Assessment Indicators/Compliance Levels ....................... C-2 
C.3 
Electro-L Space Segment Assessment Indicators/Compliance Levels ................... C-2 
C.4 
MSG Space Segment Assessment Indicators/Compliance Levels .......................... C-3 
C.5 
MTG Space Segment Assessment Indicators / Compliance Levels ........................ C-3 
 

LIST OF ANNEXES 
 
 
Page 
 
Annex A: 
List of Acronyms Used in C/S T.013 ............................................................. A-1 
 
Annex B: 
GEOSAR Space Segment Testing ................................................................. B-1 
 
B.1 EIRP in SAR Channel ...................................................................... B-2 
 
B.2 Spectral Occupancy of the Downlink .............................................. B-3 
 
B.3 Spurious Output Levels .................................................................... B-3 
 
B.4 G/T of 406 MHz Repeater................................................................ B-4 
 
B.5 Channel Bandwidth and Amplitude Ripple ..................................... B-5 
 
B.6 Downlink Carrier Frequency............................................................ B-7 
 
B.7 ALC Dynamic Range ....................................................................... B-7 
 
B.8 Modulation Index ............................................................................. B-9 
 
B.9 Translation Frequencies ................................................................. B-10 
 
B.10 Intermodulation Levels .................................................................. B-11 
 
B.11 Beacon Signal Processing .............................................................. B-12 
 
Annex C: 
GEOSAR Space Segment Assessment Indicators / Compliance Levels ....... C-1 
 
Annex D: 
GEOSAR IOC Status Message ...................................................................... D-1 
 
Annex E: 
GEOSAR Commissioning Report .................................................................. E-1 
 
 
 
 
 
 
 
 
 


 
1-4 
 

1. 
INTRODUCTION 
 
 
1.1 
Purpose  
 
This document defines the recommended tests, technical measurement standards and 
procedures required for implementing on-orbit testing and commissioning of GEOSAR space 
segment payloads.  Use of these measurement standards for on-orbit testing of a GEOSAR 
space segment will provide a standardised approach for determining the quality of the SAR 
instrument performance.  Commissioning is a formal declaration by the specific GEOSAR 
commissioning authority (CA) that a SAR payload is operational with or without limitations.  
De-commissioning is a formal declaration by the commissioning authority that a GEOSAR 
SAR payload is no longer operational.  The GEOSAR commissioning authority is normally the 
country responsible for the launch, on orbit testing and operations of the GEOSAR satellite as 
listed in document C/S T.011.  However, a Cospas-Sarsat Participant may be the 
commissioning authority for GEOSAR satellites provided by international organisations. 
 
An additional objective of this document is to ensure that measurements of GEOSAR space 
segment payload parameters are in accordance with a common set of test methods and 
definitions, so that the results may be easily evaluated. 
 
 
1.2 
Scope 
 
The following three phases of GEOSAR space segment on-orbit testing are addressed: initial 
on-orbit testing, periodic testing, and routine monitoring.  The basic responsibilities, specific 
tests to be performed, and test methodologies are defined by this document. 
 
Initial on-orbit tests are performed in order to establish that a GEOSAR payload can be placed 
in service to support SAR operations.  The initial tests focus on establishing that the GEOSAR 
payload will properly interface and be interoperable with the ground segment as shown in 
Figure 1.1.  It should be noted, however, that GEOSAR space segment providers have 
developed unique implementations of the GEOSAR payload.  These implementations include 
two fundamentally different designs.  The GEOSAR payloads on the GOES, INSAT and 
Electro-L spacecraft are demodulation/remodulation type repeaters using phase modulation.  
The GEOSAR payloads on the MSG and MTG spacecraft are frequency translation type 
repeaters. 
 
If results of the initial on-orbit tests confirm that values for assessment indicators are within 
accepted thresholds, the payload can be formally commissioned.  The payload can then be used 
operationally and data exchanged as described in document C/S A.001, Cospas-Sarsat Data 
Distribution Plan. 
 


 
1-4 
 

Periodic tests to be performed year are also specified.  These tests provide measurements used 
to confirm continued on-orbit performance of the SAR payload. 
 
A list of recommended tests and a description of each test is provided in Annex B.  The test 
descriptions provide sufficient detail to define the measurement method, but are not intended 
to be specific test procedures.  It is the responsibility of the commissioning authority to develop 
test procedures that are traceable to the methods described in this document.   
 
After initiation of GEOSAR operations, the space segment operator, GEOLUT operators and 
MCC operators routinely monitor system performance as part of normal operations.  The space 
segment operator conducts routine monitoring of the on-orbit payload performance using 
telemetry and other means as deemed necessary.  GEOLUT and MCC operators can also detect 
significant changes (e.g., loss of channel, etc.).  Abnormal conditions detected by GEOLUT 
and MCC operators are reported to the commissioning authority for further tests and corrective 
action as required.  If deemed necessary, operational limitations may be placed on the use of 
the payload or it may be de-commissioned.  With respect to the MSG and MTG SAR payloads, 
the commissioning authority will advise EUMETSAT of any detected abnormal conditions, 
and any required tests will be developed jointly by the commissioning authority and 
EUMETSAT. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 1.1: GEOSAR Space Segment Interfaces  
 
 
1.3 
Reference Documents 
 
 
a. 
C/S A.001: Cospas-Sarsat Data Distribution Plan. 
 
b. C/S A.003: Cospas-Sarsat System Monitoring and Reporting. 
 
c. 
C/S G.003: Introduction to the Cospas-Sarsat System. 
406 MHz Distress 
Beacons 
GEOSAR 
406 MHz 
Repeater* 
*Unique configuration for 
each GEOSAR spacecraft 
GEOLUT 
Space Segment 
Operator 
 
Telemetry and 
Commanding 


 
1-4 
 

d. C/S R.006: Demonstration and Evaluation Plan for 406 MHz GEOSAR Systems. 
 
e. 
C/S T.001: Specification for Cospas-Sarsat 406 MHz Distress Beacons. 
 
f. 
C/S T.009: Cospas-Sarsat GEOLUT Performance Specification and Design 
Guidelines. 
 
g. C/S T.011: Description of the 406 MHz Payloads Used in the Cospas-Sarsat 
GEOSAR System. 
 
 
1.4 
Common System Units 
 
The System International (SI) units of measurement will be used for exchange of 
interoperability parameters and test results. 
 
Interpretation of technical terms in exchanged documentation will be in accordance with the 
latest edition of the "IEEE Standard Dictionary of Electrical and Electronic Terms". 
 
 
 
- END OF SECTION 1 – 
 
 
 


 
2-8 
 

2. 
ON-ORBIT SPACE SEGMENT TESTING AND COMMISSIONING 
 
 
2.1 
Initial On-orbit Tests 
 
Following the launch of each new satellite, the responsible commissioning authority conducts 
initial on-orbit tests to confirm that the GEOSAR payload is functioning within the 
performance range as specified in C/S T.011.  The initial on-orbit tests to be conducted and the 
associated test methods are listed in Annex B.  The GEOSAR space segment commissioning 
authorities are identified below. 
 
 
Spacecraft 
 
Space Segment Operator 
Commissioning Authority 
 
 
GOES  
 
 
USA  
 
 
USA 
 
Electro-L 
 
 
Russia  
 
 
Russia 
 
Insat 
 
 
 
India  
 
 
India 
 
MSG  
 
 
EUMETSAT  
 
France 
MTG  
 
 
EUMETSAT  
 
France 
 
The data from the initial on-orbit tests will be used to establish baseline values of system 
parameters and to ensure assessment indicators are within previously established limits or to 
establish new limit values.  The assessment indicators are identified in Annex C.   
 
Some of the tests require beacon signal processing similar to that done by GEOLUTs in order 
to establish end-to-end performance.  GEOSAR commissioning authorities that do not have 
this capability can request assistance in conducting these tests from a GEOLUT operator 
located in the repeater coverage area.   
 
It is the responsibility of each commissioning authority to develop the procedures unique to the 
satellite and test facility for conducting tests on the GEOSAR instrument.  Such procedures 
shall be traceable to the methods described in this document.  Alternate methods can be 
considered but must be described in detail with the test result documentation provided with the 
commissioning report.  In addition, other Participants may perform tests on the GEOSAR 
instrument.  However, these tests shall conform to the methods described herein and the test 
procedures shall be provided to the responsible space segment operator beforehand to ensure 
the safety of the GEOSAR spacecraft.  Furthermore, all Participants conducting tests shall 
conduct appropriate co-ordination within Cospas-Sarsat to ensure that there is no negative 
impact on Cospas-Sarsat operations.   
 
The initial on-orbit tests provide a set of baseline values for the assessment indicators at the 
time the satellite begins operations.  The baseline values can be compared with pre-launch data 
to determine if on-orbit operation is nominal at launch, and with results from subsequent on-
orbit tests to monitor on-going performance trends. 
 


 
2-8 
 

The commissioning authority will analyse the initial on-orbit test data and prepare a post launch 
test report.  The report will include the results of the tests along with a description of the test 
methods sufficient to allow interpretation of the data.  The test report shall be provided to the 
Cospas-Sarsat Secretariat as an attachment to the commissioning report. 
 
 
2.2 
Commissioning Procedure 
 
Commissioning is a formal declaration by the commissioning authority that the on-orbit 
GEOSAR instrument assessment indicators meet the required compliance levels and that the 
equipment is operational as part of the GEOSAR system.  Commissioning may be declared 
with operational limitations if some compliance levels are not met and limited operation is 
deemed feasible.  In such a case the status of the GEOSAR instrument is designated as being 
at “limited operational capability” (LOC).  
 
Performing the initial on-orbit tests and preparing a report may be time consuming.  During 
this time valid operational data will normally be available from the satellite payload that is 
under test.  In view of this, an initial operational capability (IOC) status may be declared for 
the payload before the commissioning report is completed.  This may be done at the option of 
the commissioning authority after sufficient tests have been conducted to establish confidence 
that use of the GEOSAR data will not cause unnecessary expenditure of SAR resources.   
 
Satellite payload IOC is declared with a SIT 605 message issued on behalf of the 
commissioning authority by the MCC associated with the commissioning authority.  The 
information to be included in the SIT 605 IOC message is detailed at Annex D.  Once declared, 
IOC status shall remain in effect until commissioning is completed which shall normally be no 
more than 90 days after IOC status was declared.  For the first MSG SAR payload (MSG-1), 
IOC will last approximately 6 months, and will not be completed until all the other satellite 
instruments (e.g. SAR and non-SAR instruments) have been fully commissioned. 
 
Commissioning an on-orbit GEOSAR instrument consists of confirming the basic health and 
safety of the payload and the measurement and analysis of post launch test data to verify 
compliance or non-compliance with the expected values of the assessment indicators.  
Figure 2.1 shows the general commissioning procedure.  Upon completion of all tests, the 
commissioning authority will evaluate the assessment indicators and prepare a commissioning 
report as shown in Annex E.  The commissioning report will designate the status of the 
GEOSAR instrument as either being either at full operational capability (FOC) or limited 
operational capability (LOC).  The commissioning report shall be distributed by the MCC 
associated with the commissioning authority to all MCCs in the Cospas-Sarsat system using a 
SIT 605 message issued on behalf of the commissioning authority. 
 
The commissioning authority shall provide a copy of the commissioning report to the Cospas-
Sarsat Secretariat for permanent retention.  In the case of the MSG and MTG SAR payloads, 
the commissioning authority will provide copies of all test results and commissioning reports 
to EUMETSAT.  The Secretariat will provide copies of the report to Cospas-Sarsat Participants 
upon request. 
 


 
2-8 
 

2.3 
Satellite System Data 
 
In order for Cospas-Sarsat to operate the GEOSAR system at either an IOC, LOC or FOC 
status, the GEOSAR space segment operator shall provide the MCC associated with the 
commissioning authority with the satellite/payload information necessary for conducting daily 
operations.  This MCC shall distribute the information to GEOLUT operators in accordance 
with Cospas-Sarsat data distribution procedures as specified in document C/S A.001.  
Examples of such data are satellite ephemeris and status messages as needed to inform Cospas-
Sarsat about the state of the GEOSAR instrument.  The distribution of satellite ephemeris, 
which may precede declaration of IOC status, shall not in itself be taken as a declaration of 
IOC status. 
 
 
2.4 
Periodic Tests 
 
Periodic technical tests shall be performed yearly on each on-orbit GEOSAR instrument by the 
commissioning authority to confirm that the assessment indicators remain within the accepted 
limits and that the GEOSAR system under evaluation does not adversely affect SAR services.  
The data obtained from periodic testing can also be used to provide trend data for forecasting 
satellite operations and projecting the remaining life of the GEOSAR payload.  The specific 
periodic tests to be conducted for each payload are listed at Annex B. 
 
A copy of all test results shall be provided to the Secretariat for permanent retention.  In the 
case of the MSG and MTG payloads, the commissioning authority will provide copies of the 
test results to EUMETSAT.  Should the results of the periodic tests indicate a problem with the 
SAR payload then the appropriate course of action described in section 2.7 should be followed. 
 
 
2.5 
Routine Monitoring of the Space Segment 
 
Routine monitoring of the space segment shall be performed by the space segment operator, as 
well as GEOLUT and MCC operators.  By monitoring the satellite telemetry information the 
space segment operator might be able to identify potential problems before they impact on SAR 
services.  GEOLUT operators are able to identify problems by noting changes in GEOLUT 
performance (e.g., satellite tracking performance or number of processing anomalies 
generated), whereas MCC operators might be able to identify problems by comparing the alerts 
produced by the GEOSAR system with information concerning distress events obtained from 
other sources. 
 
All problems or potential problems with the payload detected by either a space segment, 
GEOLUT, or an MCC operator shall be reported to the applicable commissioning authority.  
In the case of the MSG and MTG SAR payloads, the commissioning authority will advise 
EUMETSAT of all / any problems, and actions proposed to investigate the matter.  The 
commissioning authority shall then conduct tests to confirm the health of the payload.  Should 
these tests indicate a problem with the SAR payload then the appropriate course of action 
described in section 2.7 shall be followed. 


 
2-8 
 

2.6 
De-commissioning Procedure 
 
De-commissioning is a formal declaration by the GEOSAR commissioning authority that a 
GEOSAR payload is no longer a part of the GEOSAR system.  A GEOSAR instrument that 
cannot meet the performance requirements for reliable Cospas-Sarsat service will be de-
commissioned.  An operational GEOSAR instrument may also be de-commissioned by the 
space segment operator due to general spacecraft health and safety issues.  In this case, the 
spacecraft operator shall notify the commissioning authority that the SAR instrument should 
be de-commissioned.  The commissioning authority would be responsible for distributing this 
information via the MCC network, and providing a copy to the Secretariat for permanent 
retention.  A de-commissioned payload can later be re-commissioned, with or without 
limitations, based on an evaluation of current values of the assessment indicators and the need 
within Cospas-Sarsat. 
 
 
 


 
2-8 
 

Space Segment
Operator Launches
Satellite
Commissioning
Authority Conducts
Commissioning Tests
Tests Indicate
Payload Adversely Affects
SAR Operations?
Commissioning Authority
Declares Payload at Initial
Operational Capability (IOC)
Commissioning Authority
Prepares and Reviews
Commissioning Report
Payload Fully
Satisfies Commissioning
Requirements?
Commissioning Authority
Declares Payload at Full
Operational Capability
(FOC)
Payload Satisfies
Requirements for Limited
Operational Capability
(LOC)?
Commissioning Authority
Declares Payload at LOC,
and Indicates Limitations or
Special GEOLUT
Processing Requirements
Commissioning
Authority and Space
Segment Operator
Investigate Situation
Secretariat Prepares Updates
to System Documents
GEOLUT Operators Process
and Distribute Alert Data from
GEOSAR Payload
Yes
No
Yes
No
No
Yes
 
Note: 
The MSG and MTG Payload Commissioning Authority will provide EUMETSAT copies of all  
Payload test results and reports. 
Figure 2.1:  GEOSAR Payload Commissioning Procedure 


 
2-8 
 

2.7 
Space Segment Problem Reporting and Investigation Procedures 
 
Any space segment, GEOLUT or MCC operator that detects anomalies of a GEOSAR 
instrument during routine monitoring or system operation shall inform the relevant 
commissioning authority so that special tests can be conducted and possible corrective action 
(e.g., switch to backup payload, etc.) taken.  GEOLUT and MCC operators will report problems 
to the responsible commissioning authority through the associated MCC in accordance with 
procedures given in C/S A.001, and space segment operators shall report anomalies to the 
commissioning authority via the most effective means available.   
 
Upon being made aware of a possible problem with the GEOSAR payload, the commissioning 
authority shall advise the space segment operator, and conduct an investigation to evaluate the 
status and performance of the instrument.  Based on the results of the investigation, the 
commissioning authority shall take one of the courses of action described below. 
 
a. 
Should the investigation identify a serious problem with the payload which 
renders it unusable for SAR purposes, the commissioning authority shall de-
commission the payload in accordance with section 2.6. 
 
b. 
Should the investigation identify a problem which confirms degraded payload 
performance, but indicates that the instrument is still useful for SAR purposes, 
the commissioning authority shall distribute an update of the payload status via 
the MCC network, with a copy also provided to the Secretariat and to the space 
segment operator.  The update shall specifically identify: 
 
- 
the problem with the payload; 
 
- 
the impact on GEOLUT processing; 
 
- 
the impact on the quality of distress alerts produced; and 
 
- 
any special GEOLUT processing required.  
 
c. 
Should the investigation not confirm the problem or conclude that there is a 
problem which does not impact on GEOSAR performance, the commissioning 
authority shall liaise with the organisation which identified the problem to 
confirm that GEOSAR performance is not affected.  A copy of the conclusions 
shall also be provided to the Secretariat for retention.  There would be no 
requirement to advise other Cospas-Sarsat Participants of the results of the 
investigation in such a circumstance. 
 
 


 
2-8 
 

Potential Payload
Problem Identified to
Commissioning
Authority
Commissioning
Authority Conducts
Investigation to
Evaluate Problem
Investigation
Confirms that a Payload
Problem Exists?
Problem
Renders the Payload
Unusable for SAR?
Commissioning Authority
Decommissions Payload
Commissioning Authority
Provides Payload Update
Status and Additional
Guidance via MCC Network
Commissioning Authority
Advises the Organisation/
Participant which Filed the
Problem Report and the
Secretariat of the Results
No
Yes
No
Yes
 
 
Note: 
The MSG and MTG Payload Commissioning Authority will provide EUMETSAT copies of all 
Payload test results and reports. 
 
Figure 2.2:  GEOSAR Problem Reporting and Investigation Procedures 
 
 
 
- END OF SECTION 2 - 
 

ANNEXES TO THE DOCUMENT 
GEOSAR 
SPACE SEGMENT  
COMMISSIONING STANDARD 
 
 
 
 
 
 
 
 
 
 


 
A-1 
 

ANNEX A 
 
 
LIST OF ACRONYMS USED IN C/S T.013 
 
AGC  .................. automatic gain control 
ALC.................... automatic level control 
 
BW  .................... bandwidth 
 
C/N ..................... carrier-to-noise power ratio 
C/No ................... carrier-to-noise density ratio  
cw ....................... continuous wave 
 
dB ....................... decibel 
dBHz  ................. decibel relative to one Hertz 
dBm  ................... decibel above one milliwatt 
dBW .................... decibel above one Watt 
 
EIRP  .................. equivalent isotropically radiated power 
EOC.................... edge of coverage 
 
fc ......................... carrier frequency 
FOC…………….full operational capability 
FOV.................... field of view 
 
GEOLUT............ LUT in a GEOSAR system 
GEOSAR............ geostationary satellite system for search and rescue 
GOES ................. Geostationary Operational Environmental Satellite 
G/T  .................... gain-to-noise temperature ratio 
 
IF ........................ intermediate frequency 
INSAT ................ Indian National Satellite 
IOC ..................... interim operational capability 
 
K ......................... Kelvin 
k.......................... Boltzmann's constant 
kHz  .................... kilohertz 
 
LOC ……………limited operational capability 
LNA ................... low noise amplifier 
 
MHz  .................. megahertz 
ms  ...................... milliseconds 
MSG ................... Meteosat Second Generation 
MTG ................... Meteosat Third Generation 
mW  .................... milliwatt 
 


 
A-2 
 

No ....................... noise power spectral density 
 
 
PDVM ................ probability of detecting a valid message. 
 
RBW .................. resolution bandwidth 
RHCP  ................ right hand circular polarisation 
 
SAR .................... search and rescue 
S/No  ................... signal-to-noise density ratio 
 
 
 
-END OF ANNEX A- 


 
B-1 
 
 March 2021 
 
 
 
ANNEX B 
 
 
GEOSAR SPACE SEGMENT TESTING 
 
 
The table below identifies the minimum set of post launch tests to be completed by the space 
segment operator in order to establish initial commissioning of a GEOSAR payload.  Each 
space segment operator is also encouraged to conduct other tests that may more fully 
characterise payload performance.  Selected tests are repeated yearly. 
 
Table B.1: 
List of Post Launch Tests 
 
 
Parameter Tested 
GOES 
INSAT MSG Electro-L 
MTG 
B.1 
Equivalent Isotropically Radiated Power 
(EIRP) in SAR Channel 
1,2 
1,2 
1,2 
1,2 
1,2 
B.2 
Spectral Occupancy of the Downlink 


B.3 
Spurious Output Levels 


B.4 
G/T of the 406 MHz Repeater 
1,2 
1,2 
1,2 
1,2 
1,2 
B.5 
Channel Bandwidth and Amplitude Ripple 
1,2 
1,2 
1,2 
1,2 
1,2 
B.6 
Downlink Carrier Frequency 
1,2 
1,2 
1,2 
1,2 
1,2 
B.7 
ALC Dynamic Range  


N/A 
N/A 
N/A 
B.8 
Modulation Index  


N/A 

N/A 
B.9 
Translation Frequencies 
1,2 
1,2 
1,2 
1,2 
1,2 
B.10 
Intermodulation and Harmonic Levels 


B.11 
Beacon signal processing 


Notes:  1.  Commissioning test. 
 
 
2.  This test is also performed periodically at yearly intervals. 
 
The following pages of this annex provide a general description of each test.  It should be noted, 
however, that each space segment operator has developed a unique implementation of the 
GEOSAR payload.  These implementations include two fundamentally different designs.  The 
GEOSAR payloads on the GOES Electro-L and INSAT spacecraft are remodulation type 
repeaters using phase modulation.  The GEOSAR payload on the MSG and MTG spacecraft 
are frequency translation type repeaters.  It is the responsibility of each commissioning 
authority, in co-operation with the space segment operator, to develop detailed procedures 
unique to his ground test facility for conducting these tests.  Such procedures where possible 
shall be traceable to the methods described in this document.  Alternate methods can be 


  
B-2 
 

considered but must be agreed to in advance by the space segment operator and described in 
detail by the commissioning authority as part of the post launch test report. 
 
The performance parameters to be measured by these tests and their values are listed in 
Annex C as assessment indicators. 
 
 
B.1 
EIRP IN SAR CHANNEL 
 
B.1.1 OBJECTIVE 
 
The objective of this test is to measure the SAR instrument downlink equivalent isotropically 
radiated power (EIRP).  The measured value will be compared with the level specified in the 
Description of the 406 MHz Payloads Used in the Cospas-Sarsat System, C/S T.011.  The test 
should be conducted for each operational mode and redundancy configuration. 
 
B.1.2 PROCEDURE 
 
The general procedure to be adopted for remodulation repeaters (e.g., GOES and INSAT 
payloads) for determining the EIRP is to command the phase modulation off and measure the 
downlink carrier level at the ground receiving station.  With the phase modulation off the total 
power is in the carrier.  A common technique is to measure the C/No(dn) at an IF point in the 
receiving ground station.  A spectrum analyser is the preferred instrument for use in making 
the measurement.  The EIRP is then derived using the following link equation. 
 
EIRP = C/No(dn) - G/T(gs) + Lpath + Lpol + k (dBm) 
 
Where: 
 
 
C = SAR instrument downlink carrier at the receiving station (dBm) 
 
 
No(dn) = noise power spectral density at the ground receiving system.  The SAR 
transponder up-link noise is not included in No(dn) since the phase 
modulation is turned off.  (dBm/Hz) 
 
 
G/T(gs) = receiving station antenna gain to system noise temperature ratio.  (dB/K) 
 
 
Lpath = free space path loss from the satellite to the ground station.  (dB) 
 
 
Lpol = 
loss due to polarisation mismatch between the ground receive antenna and 
the satellite antenna.  (dB) 
 
 
k = 
Boltzmann's constant = -198.6  (dBm/Hz-K) 
 
Measure the downlink received C/N in the ground receiver IF using a spectrum analyser 
resolution bandwidth setting such that C/N 20 dB.   The value read for C can then be taken to 
be entirely due to the carrier since the carrier power is 100 times the noise power.  Position the 
analyser marker away from the carrier for making the No(dn) measurement.  No(dn), and 
possibly C/No(dn), can be measured directly using the spectrum analyser if it has an automatic 
noise density-measuring feature.  If not, the noise power, N, in the resolution bandwidth can 


  
B-3 
 

be converted to No(dn) by applying the bandwidth correction plus any other correction factors 
specified for the analyser.   
 
 
B.2 
SPECTRAL OCCUPANCY OF THE DOWNLINK 
 
B.2.1 OBJECTIVE 
 
The objective of this test is to measure the spectral occupancy of the downlink spectrum in 
order to identify normal in-band operation and the presence of any out-of-band emissions.  The 
test must be performed separately in each operating mode of the SAR instrument.   
 
B.2.2 PROCEDURE 
 
The downlink spectrum in a 1 MHz band centred on the downlink carrier is measured using a 
spectrum analyser connected in the ground receiver 1st IF ahead of any narrow band filtering 
and the phase demodulator.  A spectrum analyser resolution bandwidth of 1 kHz or lower is 
recommended.  The measurement should be made if possible during a period when no 
406 MHz band interfering signals are being received and retransmitted by the spacecraft.  
Several plots of the measured spectrum should be taken, particularly if abnormal performance 
is suspected.  Sufficient calibration data must be provided in order to relate the measured carrier 
component to the spacecraft output (using link budget).  The test should be repeated in a 2 MHz 
band centred on the downlink carrier. 
 
The spectrum is analysed for the presence of any anomalous spectral emissions.  Since there is 
very little Doppler frequency variation associated with geostationary satellites, signals that 
constantly appear in the spectrum at fixed frequencies are due to either on board 
electromagnetic interference (EMI) or external interference.  The source of any observed 
signals may possibly be determined by comparing spectral plots taken at various times 
throughout the day or over a number of days.  Data from the LEOSAR system may also be 
used to assist in identifying signals that originate from external sources.   
 
 
B.3 
SPURIOUS OUTPUT LEVELS 
 
B.3.1 OBJECTIVE 
 
The objective of this test is to determine the frequency and level referred to the receiver input 
of any spurious signals within the GEOSAR repeater bandwidth. 
 
B.3.2 PROCEDURE 
 
Spurious signals within the repeater bandwidth can be monitored in the demodulated baseband 
spectrum using a spectrum analyser.  These measurements should be made as accurately as 
possible; therefore, they should be made with as small a resolution bandwidth as practical 
( 100Hz).  The baseband is approximately 100 kHz and a FFT type spectrum analyser, if 
available, is a good choice for the measurement instrument.  Care must be exercised in 
identifying spurious signals generated by on-board equipment.  The signals are in general at a 
constant frequency; however, since there is very little GEOSAR Doppler shift associated with 
terrestrially emitted signals in the 406 MHz band these signals also will appear at a constant 


  
B-4 
 

frequency.  It may be necessary to take several spectrum plots over a number of days to assist 
in identifying on-board signals from terrestrial emitters.  The test personnel can also ask for 
assistance from LEOLUT operators in identifying terrestrial emitters.  The LEOSAR spacecraft 
can identify these signals due to the Doppler at the LEOSAR spacecraft. 
 
The frequency of any in-band spurious signals can be read using the spectrum analyser marker 
controls.  The level of spurious signals at the receiver input can be estimated by transmitting a 
known reference signal to the satellite to compare against the spurious signal.  The reference 
signal should be within a few kilohertz of the signal and can be adjusted to match the spurious 
signal level.  However, care must be taken to not overload the repeater.  The level of the 
reference signal at the receiver input can be estimated by performing a link calculation. 
 
 
B.4 
G/T OF THE 406 MHz REPEATER 
 
B.4.1 OBJECTIVE 
 
The objective of this test is to measure the 406 MHz SAR receiver antenna gain-to-noise 
temperature ratio, G/T(406).  The measured value will be compared with the level specified in 
C/S T.011, “Description of the 406 MHz Payloads Used in the Cospas-Sarsat GEOSAR 
System”.  The test should be conducted for each available GEOSAR receive antenna and LNA 
configuration (redundant channels, etc.).   
 
B.4.2 PROCEDURE 
 
The LNA gain on GEOSAR instruments is large enough so that the G/T is established by the 
antenna and LNA combination.  Therefore, the measurement can be made in either the 
wideband or narrow band mode. 
 
The on orbit G/T(406) can be derived by using the following link equation.   
 
 
(
)
(
)
(
)
k
L
L
up
EIRP
up
N
C

T
G
pol
path
o
+
+
+
−
=
 
Where: 
 
(
)
up
N
C
o
 = carrier to noise density ratio in the SAR repeater.  (dBHz-1) 
EIRP(up) = known up-link EIRP.  (dBm) 
Lpath  = up-link free space path loss.  (dB) 
Lpol  
= polarisation mismatch loss between the up-link antenna and the satellite 
receive antenna.   (dB) 
K 
= Boltzmann's constant = -198.6     (dBm/Hz-K) 
 
C/No(up) is calculated from the overall C/No(total) measured at the ground test facility by 
subtracting out the ground station receiver noise.  The No (total) observed at the ground station 
consists of two parts; No (total) = No (up) + No (gs) where No (gs) is the ground station receiver 
noise.  No (gs) can be measured by pointing the ground station antenna away from the GEOSAR 


  
B-5 
 

spacecraft but not in the beam width of stellar sources emitting high radio frequency energy 
levels. 
 
The general procedure is as follows. 
 
 
a. 
Up-link a known EIRP (40 dBm) at 406.025 MHz.   
 
 
b. 
Monitor the received signal using a spectrum analyser.  This can be done after 
demodulation and/or filtering to baseband.  Adjust ground station antenna 
azimuth and elevation to maximise the received level.  Set analyser resolution 
bandwidth such that C/N (total)  20 dB.  Measure values of C/No(total), C, and 
No (total).  The noise spectral density values can be measured directly using the 
spectrum analyser if it has an automatic noise density measuring feature.  If not, 
the noise power, N(total) measured in the analyser resolution bandwidth can be 
converted to No(total) by applying the bandwidth correction plus any other 
correction factors specified for the analyser. 
 
 
c. 
Adjust the ground station antenna pointing such that it points away from 
GEOSAR by at least 15 but not in the field of view (FOV) of stellar sources 
emitting high radio frequency energy levels.  Measure the clear sky ground 
station receiver noise, No (gs).   
 
 
d. 
Compute No (up) = No (total) - No (gs) and use the value to determine C/No(up) 
 
(convert as needed between numerics and dB). 
 
 
e. 
Derive 
(
)
(
)
(
)
k
L
L
up
EIRP
up
N
C

T
G
pol
path
o
+
+
+
−
=
 
 
 
B.5 
CHANNEL BANDWIDTH AND AMPLITUDE RIPPLE 
 
B.5.1 OBJECTIVE 
 
The objective of this test is to measure the bandwidth and amplitude ripple in the GEOSAR 
repeater channel.  The test must be performed for each channel bandwidth mode of operation.  
The test can be performed in the fixed gain mode on transponders that have selectable ALC 
ON/OFF, however, it is desirable to perform the test for both the fixed gain and ALC mode 
configurations. 
 
B.5.2 PROCEDURE 
 
The level of 406 MHz beacon signals received at the spacecraft is sufficiently small such that 
under normal situations a band of white noise generated by the LNA is transmitted on the 
channel.  The amplitude ripple of the channel can be estimated by observing this band of noise 
power at the ground test facility.  The observation should be done during a "quiet" period, i.e., 
no interference or large test inputs.  Swept frequency techniques may be used as an alternate 
procedure.   
 
 
B.5.2.1 
Channel frequency response (phase modulation repeater) 


  
B-6 
 

a. 
Monitor the downlink baseband signal after the ground station phase 
demodulator with the spacecraft in the narrowband mode and ALC 
disabled (fixed gain mode).  The analyser centre frequency, 
resolution bandwidth and span should be adjusted to appropriately 
display the channel data. 
 
 
b. 
Take a spectrum plot during a quiet period. 
 
 
c. 
Use the spectrum analyser offset markers to identify the 3-dB 
bandwidth.  Print a record for the test report.   
 
 
d. 
Repeat steps a through c for the following modes as applicable: 
narrowband/ALC ON, wideband/ALC OFF and wideband/ALC 
ON. 
 
 
B.5.2.2 
Channel frequency response (frequency translator repeater) 
 
 
a. 
With the spacecraft in the narrowband mode and ALC disabled, 
monitor the downlink signal in the ground station receiver IF ahead 
of any filtering that would corrupt the channel measurement.  The 
analyser centre frequency, resolution bandwidth and span should be 
adjusted to appropriately display the channel data. 
 
 
b. 
Take a spectrum plot during a quiet period. 
 
 
c. 
Use the spectrum analyser offset markers to identify the 3-dB 
bandwidth.  Print a record for the test report.   
 
 
d. 
Repeat steps a through c for the modes as applicable: 
narrowband/ALC ON, wideband/ALC OFF and wideband/ALC 
ON. 
 
 


  
B-7 
 

B.6 
DOWNLINK CARRIER FREQUENCY 
 
B.6.1 OBJECTIVE 
 
The objective of this test is to measure the GEOSAR phase modulation type repeater downlink 
carrier frequency. 
 
B.6.2 PROCEDURE 
 
The frequency of the downlink signals received at the ground test facility can be measured with 
a spectrum analyser that has a counter mode with a 1 Hz resolution.  The downlink signal for 
the phase modulation type transponder contains sufficient carrier level for isolating and 
measuring the carrier frequency.  Alternately the receiver can be turned OFF so that no 
modulation is present on the carrier when making the measurement.   
 
The general procedure is as follows. 
 
a. 
Monitor the downlink frequency in the 1st IF with the spectrum analyser.  Select 
a resolution bandwidth such that the carrier can be isolated from the modulation 
sidebands and the C/N ratio is  20 dB. 
 
b. 
Measure the carrier frequency using the analyser frequency counter mode.  
Alternate techniques may be used if the analyser does not have the counter 
mode. 
 
c. 
A minimum of 20 measurements at 1-minute intervals should be taken and 
averaged to determine the carrier frequency.  This data should also be examined 
to determine if carrier frequency drift is occurring. 
 
 
B.7 
ALC DYNAMIC RANGE 
 
B.7.1 OBJECTIVE 
 
The objective of this test is to measure the gain transfer function with the GEOSAR transponder 
in the ALC mode.  
 
 
B.7.2 PROCEDURE 
 
The gain transfer function is a measure of the transponder output power versus transponder 
input power.  This procedure uses unmodulated carrier signals only. The uplink signal EIRP is 
varied in level over the dynamic range of the SAR receiver, from input noise to the maximum 
allowable signal into the transponder.  The resulting downlink carrier level, Cd, is measured in 
the pre-detection IF bandwidth using a spectrum analyzer. This measurement can also be made 
after phase demodulation for phase modulation type SAR repeaters such as those on the GOES 
spacecraft. Plot the transfer curve using the measured data. 
 


  
B-8 
 

The general procedure is as follows: 
 
a. 
Begin with no uplink.  Monitor the downlink to ensure that no active beacons 
or interference signals are present. Record the downlink carrier signal strength. 
Note that the level of the 1544.5 MHz carrier for the phase modulation repeaters 
will remain essentially constant throughout the test. 
 
b. 
Establish a CW uplink signal at a frequency near mid-band and an EIRP of 
5 Watts. Observe this signal on the downlink using the spectrum analyzer.  
Increase the uplink signal level to the point where the observed downlink signal, 
Cd, does not continue to increase, i.e., the AGC is operating at the upper limit 
of the dynamic range.  Record the uplink EIRP and the value of the measured 
downlink signal and the SAR receiver No (measured a few kHz away from Cd 
using the spectrum analyzer).  The downlink should be free of interference when 
making these measurements. 
 
c. 
Decrement the CW uplink signal in 1 dB steps; monitor the downlink to ensure 
there is no interference present and record the measured values of Cd, No and 
the uplink EIRP.  Continue to reduce the uplink signal by 1 dB and make the 
measurements until Cd approaches the receiver noise level. 
 
d. 
Repeat steps a through c for the spacecraft modes as applicable: 
narrowband/ALC ON, wideband/ALC ON. 
 
 
The following equation and data from this test may also be used to derive an estimate of SAR 
repeater gain to noise temperature ratio, G/T(406). 
(
)
(
)
(
)
k
L
L
up
EIRP
up
N
C

T
G
pol
path
o
+
+
+
−
=
 
 
Where: 
 
(
)

T
G
 =SAR 406 MHz repeater gain to noise temperature ratio (dBK-1). 
(
)
up
N
C
o
 = carrier to noise density ratio in the SAR repeater.  (dB-Hz). 
N0 = noise power spectral density in a 1 Hz bandwidth. 
EIRP(up) = known up-link EIRP.  (dBm). 
Lpath  = up-link free space path loss.  (dB). 
Lpol  
= polarisation mismatch loss between the up-link antenna and the satellite 
receive antenna.   (dB). 
K 
= Boltzmann's constant = -198.6 (dBm/Hz-K). 
 
The AGC functions to maintain a constant power at the spacecraft receiver output. Note the 
point on the AGC curve that is 3 dB below the maximum. At this point the test uplink input 
referred to the SAR low noise amplifier input, Cu, and total receiver noise power, N, in the 


  
B-9 
 

channel bandwidth are equal; therefore, Cu /N = 0 dB.  Knowing also that N = kTB = No B 
where B is the channel bandwidth, the value of C/No(up) = B for this specific uplink signal. 
 
The G/T(406) can be derived by using the above equation with 
(
)
up
N
C
o
 = B and EIRP(up) = 
the value of the uplink EIRP used for the point on the AGC curve that is 3 dB below the 
maximum value. 
 
 
B.8 
MODULATION INDEX 
 
B.8.1 OBJECTIVE 
 
The purpose of this test is to measure the modulation index for phase modulated type GEOSAR 
repeaters.  The test should be conducted for each of the available bandwidth/ALC operating 
modes: narrow band/ALC ON, narrow band/ALC OFF, wide band/ALC ON, and wide 
band/ALC OFF. 
 
B.8.2 PROCEDURE 
 
The difference in the received downlink carrier level when the SAR receiver is switched from 
OFF to ON (i.e., carrier suppression technique) is measured at the ground test facility.  Distress 
beacon signals are very small resulting in the receiver output being mostly noise.  This band of 
noise (wide band or narrow band) is phase modulated onto the GEOSAR spacecraft downlink 
carrier.  The general procedure is as follows and should be repeated for each bandwidth/ALC 
mode of operation. 
 
a. 
Configure the space segment receiver to OFF.  Monitor the downlink carrier 
with a spectrum analyser.  Select an analyser resolution such that the received 
C/N  20 dB.  Record the level of CRx_off. 
 
b. 
Configure the space segment receiver to ON.  Monitor the downlink carrier with 
a spectrum analyser.  Select an analyser resolution such that the received C/N  
20 dB.  Record the level of CRx_on.  The downlink spectrum should be monitored 
during the measurement of CRx_on.  to assure that no large interfering signal is 
in the band when making the measurements.  This condition would result in 
higher values of modulation index. 
 
c. 
Compute value of carrier suppression as of CRx_off.  - CRx_on. 
 
d. 
Repeat steps a through c for each bandwidth/ALC mode. 
 
e. 
The test data should include the carrier suppression values with the associated 
modulation index. 
 
 


  
B-10 
 

B.9 
TRANSLATION FREQUENCIES 
 
B.9.1 OBJECTIVE 
 
A 406 MHz signal at the repeater input is translated to a specific frequency in the downlink 
spectrum as a function of the spacecraft local oscillators.  The objective of this is to measure 
the frequency in the downlink to which a 406 MHz beacon signal is translated.   
 
B.9.2 PROCEDURE 
 
The frequency of the downlink signals received at the ground test facility can be measured with 
a spectrum analyser that has a counter mode with a 1 Hz resolution.  A 406 MHz band cw test 
signal at a precise frequency must be transmitted from the ground test facility to the satellite 
for use in measuring the translation frequency.  In order to obtain accurate measurements, the 
cw test uplink signal, the spectrum analyser, and all down conversions in the ground station 
receiver must be locked to a precision frequency standard. 
 
 
 
B.9.2.1 
Beacon to downlink translation frequency (phase modulation repeater). 
 
This test can be performed in either the wideband or narrowband mode. 
 
 
a. 
With the spacecraft in the wideband mode, uplink a 406.05 MHz 
(406.025 MHz if in narrowband mode) cw carrier at 10 dBW EIRP. 
 
 
b. 
Monitor the translated downlink frequency in the baseband 
spectrum after phase demodulation.  Select a spectrum analyser 
resolution bandwidth such that the received signal has a C/N ratio  
20 dB. 
 
 
c. 
Measure the carrier frequency using the analyser frequency counter 
mode.  Alternate techniques may be used if the analyser does not 
have the counter mode.   
 
 
d. 
A minimum of 20 measurements at 30-second intervals should be 
taken and averaged to determine the carrier frequency.  This data 
should also be examined to determine if the translation oscillators 
are drifting in frequency.   
 
 
B.9.2.2. 
Beacon to downlink translation frequency (frequency translation repeater). 
 
 
a. 
With the spacecraft in the wideband mode, uplink a 406.05 MHz 
(406.025 MHz if in narrowband mode) cw carrier at 10 dBW EIRP. 
 
 
b. 
Monitor the translated downlink frequency in the 1st IF with the 
spectrum analyser.  Select a resolution bandwidth such that the 
received signal has a C/N ratio  20 dB. 
 


  
B-11 
 

c. 
Measure the carrier frequency using the analyser frequency counter 
mode.  Alternate techniques may be used if the analyser does not 
have the counter mode. 
 
 
d. 
A minimum of 20 measurements at 30-second intervals should be 
taken and averaged to determine the carrier frequency.  This data 
should also be examined to determine if the translation oscillators 
are drifting in frequency. 
 
 
B.10 
INTERMODULATION LEVELS 
 
B.10.1 OBJECTIVE 
 
The objective of this test is to determine the levels of any intermodulation products in the SAR 
channel.  The SAR transponder operates with inputs from multiple users at different 
frequencies in the band. There are also uplinks from unauthorized users which are called 
interferers. If the levels of intermodulation products in the transponder band are too high, they 
can interfere with beacon signals that are at or near the same frequencies as the intermodulation 
products. 
 
The test should be conducted in all modes as applicable to the specific type of GEOSAR 
repeater. 
 
B.10.2 PROCEDURE 
 
Two equal large level carriers at 1 kHz separation shall be applied at the transponder input. The 
downlink spectrum is examined with a spectrum analyzer in the pre-detection IF bandwidth for 
third order intermodulation products. This measurement can also be made after phase 
demodulation for phase modulation type SAR repeaters such as those on the GOES spacecraft.  
A record of the measured spectrum should be recorded to support analysis and for inclusion in 
the test report. The level of intermodulation products in dB below the test signal output shall 
be measured. 
 
 
B.10.2.1 Procedure for SAR repeaters on GOES spacecraft. 
 
 
a. 
Determine the test signal input power levels for the repeater mode 
being tested. Each test signal, Sin, must be 7 dB above total receiver 
noise level for modes with ALC ON. When in fixed gain mode 
(FGM), Sin, is set to 2 dB above total receiver noise level. 
 
 
 
The receiver noise is equal to kTBn where Bn is the noise bandwidth 
of the receiver for the specific operating mode. Bn can be estimated 
by using the 3 dB filter bandwidth measured during test B.5.  
 
 
 
The input Sin/No of the test signal can be determined as follows. 
 
ALC modes  Sin/No = Bn + 7 dB-Hz 
 
 
FGM   
Sin/No = Bn + 2 dB-Hz 


  
B-12 
 

b. 
Select a spacecraft configuration to be tested and monitor the 
received baseband using the spectrum analyzer.  Uplink two test 
signals with the frequencies and power necessary to achieve the 
Sin/No values listed in the following table.  
 
Configuration 
F1 (MHz) 
F2 (MHz) 
Bn (dB-Hz) 
Sin/No 
(dB-Hz) 
Specification 
Relative to Sin 
WB- ALC 
406.0495 
406.0505 
Bwb per test B.5 
Bwb + 7 
-30 dB 
WB–Fixed Gain 
406.0495 
406.0505 
Bwb per test B.5 
Bwb + 2 
-20 dB 
NB – ALC 
406.0245 
406.0255 
Bnb per test B.5 
Bnb + 7 
-30 dB 
NB- Fixed gain 
406.0245 
406.0255 
Bnb per test B.5 
Bnb + 2 
-20 dB 
Bwb is the receiver noise bandwidth measured per test B.5 when in the wide band mode. 
Bnb is the receiver noise bandwidth measured per test B.5 when in the narrow band mode. 
 
 
c. 
Record the spectrum.  For wideband examine the spectrum from 48 
to 53 kHz for spurious signals.  For narrowband, examine the 
spectrum from 23 kHz to 28 kHz for spurious signals. Any spurious 
signals observed must be below the input signal in accordance with 
column 6 of the above table. 
 
 
d. 
Change modes and repeat step a and b until all modes have been 
tested. 
 
 
B.11 
BEACON SIGNAL PROCESSING 
 
B.11.1 OBJECTIVE  
 
The purpose of this test is to demonstrate that 406 MHz beacon signals relayed through the 
GEOSAR repeater are properly processed by a GEOLUT with sufficient reliability for 
distribution within the Cospas-Sarsat network.   
 
B.11.2 PROCEDURE 
 
Beacon output signals at specific levels will be transmitted to the GEOSAR and relayed to a 
GEOLUT for reception and processing.  The test, therefore, requires use of beacon signal 
processing as done by a GEOLUT.  Any GEOSAR spacecraft operator that does not have this 
capability can request assistance from a GEOLUT operator located in the coverage area. 
 
This test is based on a modification of test T-1, Processing Threshold and System Margin, as 
described in document C/S R.006.  A controlled test beacon simulator is necessary for the test.  
It is required that the EIRP of this beacon simulator be adjustable, that multiple identification 
codes be transmitted, and that the burst transmissions are controllable in message blocks as 
described in C/S R.006.  The general procedure is as follows. 
 
 
a. 
Place the beacon simulator in the satellite FOV with an elevation angle to the 
satellite > 5 degrees.   


  
B-13 
 

b. 
Configure the satellite for the wideband/fixed gain mode. 
 
 
c. 
Configure the beacon simulator as follows: 
 
 
(i) 
Set the EIRP to +37 dBm. 
 
 
(ii) 
Use 3 to 4 identification codes to allow immediate restarting of the test 
after a GEOLUT measurement. 
 
 
(iii) 
Transmit 100 message blocks. 
 
 
d. 
GEOLUT operator measure the number of valid messages received and the 
C/No of the beacon message for the +37 dBm signal. 
 
 
e. 
Calculate the probability of detecting a valid message (PDVM) as the number 
of valid messages processed divided by total number of message blocks 
transmitted.  The PDVM should be >0.99. 
 
 
f. 
Reset the beacon simulator as follows: 
 
 
(i) 
Reduce the EIRP from +37 dBm by (C/No - 26) dB where C/No is the 
value measured in step d.  This will provide a received beacon signal 
with a C/No 26 dB-Hz.   
 
 
(ii) 
Use the same 3 to 4 identification codes as in step 3 to allow immediate 
restarting of the test after a GEOLUT measurement. 
 
 
(iii) 
Transmit 100 message blocks. 
 
g. 
Calculate the PDVM as the number of valid messages processed divided by total 
number of message blocks transmitted.  The PDVM should be >0.95. 
 
 
 
-END OF ANNEX B- 
 
 


 
C-1 
 

ANNEX C 
 
 
GEOSAR SPACE SEGMENT ASSESSMENT 
INDICATORS / COMPLIANCE LEVELS 
 
 
Table C.1: 
GOES Space Segment Assessment Indicators / Compliance Levels 
 
Assessment Indicator 
Compliance Level Reference 
L-band EIRP 
C/S T.011, Table 3.3 
Spectral occupancy (of downlink) 
C/S T.011, Figure 3.2 
G/T of 406 MHz receiver 
C/S T.011, Table 3.2 
Modulation index 
C/S T.011, Table 3.3 
Downlink carrier frequency (long term) 
C/S T.011, Table 3.3 
Translation frequency 
 
Wideband mode (relative to 406.05 MHz in) 
 
Location in baseband 
 
Narrowband mode (relative to 406.025 MHz in) 
 
Location in baseband 
C/S T.011, Section 3.3 
Narrowband channel bandwidth (relative to 
406.025 MHz centre frequency) 
 
 
 
 
1 dB Bandwidth  
 
 
 
 
3 dB Bandwidth 
20 dB Bandwidth 
C/S T.011, Table 3.2 
Wideband channel bandwidth (relative to 
406.05 MHz centre frequency) 
 
 
 
 
1 dB Bandwidth  
 
 
 
3 dB Bandwidth 
20 dB Bandwidth 
C/S T.011, Table 3.2 
ALC dynamic range 
C/S T.011, Table 3.2 
Intermodulation Levels 
C/S T.011, Table 3.3 
Beacon signal Probability of Detecting Valid 
Messages 
C/S T.009, Section 5.1 
 


 
C-2 
 

Table C.2: 
INSAT Space Segment Assessment Indicators / Compliance Levels 
 
Assessment Indicator 
Compliance Level Reference 
EIRP in SAR channel 
C/S T.011, Table 4.2 
Spectral occupancy (of downlink) 
C/S T.011, Figures 4.2a and 4.2b 
G/T of 406 MHz receiver 
C/S T.011, Table 4.2 
Modulation index 
C/S T.011, Table 4.2 
Downlink carrier frequency Stability 
C/S T.011, Table 4.2 
Translation frequency stability 
 
Wideband mode (relative to 406.05 MHz in)
 
 Location in baseband 
 
Narrowband mode (relative to 406.025 MHz in)
 
 Location in baseband 
C/S T.011, section 4.3 
 
Narrowband channel 1 dB bandwidth (relative to 
406.025 MHz) 
C/S T.011, Table 4.2 
Wideband channel 1 dB bandwidth (relative to 
406.05 MHz) 
C/S T.011, Table 4.2 
ALC dynamic range 
C/S T.011, Table 4.2 
Beacon signal Probability of Detecting Valid 
Messages 
C/S T.009, Section 5.1 
 
 
Table C.3: 
Electro-L Space Segment Assessment Indicators / Compliance Levels 
 
Assessment Indicator 
Compliance Level Reference 
EIRP in SAR channel 
C/S T.011, Table 5.3 
Spectral occupancy (of downlink) 
C/S T.011, Figures 5.1a and 5.1b. 
G/T of 406 MHz receiver 
C/S T.011, Table 5.2 
Downlink frequency with 406 MHz signal input 
C/S T.011, Table 5.3 
Translation frequency stability:  long term 
 
One day 
 
1.0 second 
C/S T.011, Table 5.3 
Channel bandwidth (3 dB relative to 406.05 MHz) 
C/S T.011, Table 5.2 
Beacon signal Probability of Detecting Valid 
Messages  
C/S T.009, Section 5.1 
 


 
C-3 
 

Table C.4: 
MSG Space Segment Assessment Indicators / Compliance Levels 
 
Assessment Indicator 
Compliance Level Reference 
EIRP in SAR channel 
C/S T.011, Table 6.2 
Spectral occupancy (of downlink) 
C/S T.011, Figure 6.2a 
G/T of 406 MHz receiver 
C/S T.011, Table 6.2 
Downlink carrier frequency (with 406.05 MHz in) 
C/S T.011, Table 6.2 
Translation frequency accuracy:  
C/S T.011, Table 6.2 
Channel bandwidth: 0.5 dB relative to 406.05 MHz 
Noise Equivalent bandwidth 
C/S T.011, Table 6.2 
Beacon signal Probability of Detecting Valid 
Messages 
C/S T.009, Section 5.1 
 
 
Table C.5: 
MTG Space Segment Assessment Indicators / Compliance Levels 
 
Assessment Indicator 
Compliance Level Reference 
EIRP in SAR channel 
C/S T.011, Table 8.1 
Spectral occupancy (of downlink) 
C/S T.011, Figures 8.2 & 8.3 
G/T of 406 MHz receiver 
C/S T.011, Table 8.1 
Downlink carrier frequency (with 406.05 MHz in) 
C/S T.011, Table 8.1 
Translation frequency accuracy:  
C/S T.011, Table 8.1 
Channel bandwidth: 0.5 dB relative to 406.05 MHz 
Noise Equivalent bandwidth 
C/S T.011, Table 8.1 
Beacon signal Probability of Detecting Valid 
Messages 
C/S T.009, Section 5.1 
 
 
 
 
 
 
 
- END OF ANNEX C - 
 


 
D-1 
 

ANNEX D 
 
 
GEOSAR IOC STATUS MESSAGE 
 
 
Should the test results confirm that the payload satisfies IOC requirements, the commissioning 
authority shall distribute the information identified in sections 1 and 2 below throughout the 
Cospas-Sarsat system using a SIT 605 message.  Items not tested must be so noted as comments 
in the SIT 605 message. 
 
1.0 
Test Results 
 
SPACECRAFT -  _________ 
 
 
Date  
Test 
Result 
Pass / Fail 
Comments 
B.1 
EIRP in SAR Channel 
 
 
 
B.2 
Spectral Occupancy of the Downlink 
 
 
 
B.3 
Spurious Output Levels 
 
 
 
B.4 
G/T of 406 MHz Repeater 
 
 
 
B.5 
Channel Bandwidth and Amplitude Ripple 
 
 
 
B.6 
Downlink Carrier Frequency  
 
 
 
B.7 
ALC Dynamic Range  
 
 
 
B.8 
Modulation Index 
 
 
 
B.9 
Translation Frequencies 
 
 
 
B.10 Intermodulation and Harmonic Levels 
 
 
 
B.11 Beacon Signal Processing 
 
 
 
Note: 
Graphics and supplementary data may be provided as attachments to this report and provided to the 
Cospas-Sarsat Secretariat for permanent retention. 
 
 


 T13OCT25.01 
D-2 
 

2.0 
IOC Mode 
 
The spacecraft will be operated in the following IOC mode. 
 
 
Channel Bandwidth   
WB or NB 
 
ALC  
 
 
ON or Off 
 
Operational Limitations: 
 
 
 
Commissioning Authority: 
 
 
 
 
 
 
Date:  
 
 
 
 
 
- END OF ANNEX D - 
 
 


 
 
 
E-1 
 

ANNEX E 
 
 
GEOSAR COMMISSIONING REPORT 
 
Should the test results confirm that the GEOSAR payload satisfies commissioning 
requirements, the commissioning authority shall distribute the information contained in the 
commissioning report as identified below throughout the Cospas-Sarsat system using a SIT 
605 message.   
 
Satellite: ___________  
 
Date __________ 
 
Configuration 
 
Pass/Fail* 
Operational, 
Limited Operation, 
Not Operational 
 
Comments 
NB/Fixed gain 
 
 
 
NB/ALC On 
 
 
 
WB/Fixed gain 
 
 
 
WB/ALC On 
 
 
 
Payload Status: FOC or LOC 
 
Initial operational configuration: 
 
The spacecraft will initially be operated in the following mode: 
 
 
Channel Bandwidth   
WB or NB 
 
ALC  
 
 
ON or Off 
 
Operational Limitations: 
 
 
Other Remarks: 
 
 
Commissioning Authority:   
 
 
 
 
 
Date:  
 
 
-END OF ANNEX E- 
 
- END OF DOCUMENT -


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
Cospas-Sarsat Secretariat 
1250 René-Lévesque Blvd. West, Suite 4215, Montreal (Quebec) H3B 4W8 Canada 
Telephone: +1 514 500 7999 
Fax: +1 514 500 7996 
Email: mail@cospas-sarsat.int 
Website: http://www.cospas-sarsat.int