---
title: "T016: C/S T.016 Issue 1 Rev 7"
description: "Official Cospas-Sarsat T-series document T016"
sidebar:
  badge:
    text: "T"
    variant: "note"
# Extended Cospas-Sarsat metadata
documentId: "T016"
series: "T"
seriesName: "Technical"
documentType: "specification"
isLatest: true
issue: 1
revision: 7
documentDate: "October 2023"
originalTitle: "C/S T.016 Issue 1 Rev 7"
---

> **📋 Document Information**
>
> **Series:** T-Series (Technical)
> **Version:** Issue 1 - Revision 7
> **Date:** October 2023
> **Source:** [Cospas-Sarsat Official Documents](https://www.cospas-sarsat.int/en/documents-pro/system-documents)

---

DESCRIPTION OF THE
406 MHz PAYLOADS USED IN
THE COSPAS-SARSAT MEOSAR SYSTEM
C/S T.016
Issue 1 - Revision 7

![Image 1 from page 1](/images/cospas-sarsat/T-series/T016/T016_page_1_img_1.png)


DESCRIPTION OF THE
406 MHz PAYLOADS USED IN
THE COSPAS-SARSAT MEOSAR SYSTEM
HISTORY
Issue
Revision
Date
Comments


Approved by the Cospas-Sarsat Council (CSC-51)


Approved by the Cospas-Sarsat Council (CSC-55)


Approved by the Cospas-Sarsat Council (CSC-57)


Approved by the Cospas-Sarsat Council (CSC-59)


Approved by the Cospas-Sarsat Council (CSC-61)


Approved by the Cospas-Sarsat Council (CSC-64)


Approved by the Cospas-Sarsat Council (CSC-67)


Approved by the Cospas-Sarsat Council (CSC-69)

TABLE OF CONTENTS
Page
History ..................................................................................................................................................... i
Table of Contents ................................................................................................................................... ii
List of Tables ........................................................................................................................................ iii
List of Figures ....................................................................................................................................... iv
1.
INTRODUCTION .............................................................................................................. 1-1
1.1
Overview .................................................................................................................... 1-1
1.2
Purpose 1-1
1.3
Scope
1-1
1.4
Reference Documents................................................................................................. 1-1
2.
406 MHZ MEOSAR SYSTEM DESCRIPTION ............................................................. 2-1
2.1
406 MHz MEOSAR Payload Functional Description ............................................... 2-1
2.2
MEOSAR Orbit Information ...................................................................................... 2-2
2.3
MEOSAR Interoperability Parameters ....................................................................... 2-2
3.
GPS 406 MHZ MEOSAR REPEATER ........................................................................... 3-1
3.1
DASS S-Band ............................................................................................................. 3-1
3.1.1
DASS S-Band Overall Description ................................................................ 3-1
3.1.2
DASS S-Band Repeater Functional Description ........................................... 3-2
3.1.3
DASS S-Band Repeater Operating Modes .................................................... 3-2
3.1.4
DASS S-Band Repeater Spectrum Characteristics ........................................ 3-2
3.1.5
DASS S-Band Repeater Coverage Area ........................................................ 3-3
3.1.6
DASS S-Band Repeater Performance Parameters ......................................... 3-3
3.2
GPS-III L-Band .......................................................................................................... 3-5
3.2.1
GPS III Overall Description .......................................................................... 3-6
3.2.2
GPS III Repeater Functional Description ...................................................... 3-6
3.2.3
GPS III Repeater Operating Modes ............................................................... 3-6
3.2.4
GPS III Repeater Spectrum Characteristics ................................................... 3-7
3.2.5
GPS III Repeater Coverage Area ................................................................... 3-8
3.2.6
GPS III Repeater Performance Parameters .................................................... 3-8
4.
GALILEO 406 MHZ MEOSAR REPEATER ................................................................ 4-1
4.1
Galileo Overall Description ........................................................................................ 4-1
4.2
Galileo Repeater Functional Description ................................................................... 4-2
4.2.1
Payload Configuration ................................................................................... 4-2
4.2.2
Configuration of Galileo SAR Repeaters ...................................................... 4-2
4.3
Galileo Repeater Operating Mode .............................................................................. 4-2
4.4
Galileo Repeater Spectrum Characteristics ................................................................ 4-3

4.5
Galileo Repeater Coverage Area ................................................................................ 4-4
4.6
Galileo Repeater Performance Parameters ................................................................. 4-5
4.7
Galileo SAR Receiver Parameters ............................................................................. 4-6
4.7.1
Galileo SAR Bandpass Parameters ................................................................ 4-6
4.7.2
Galileo SAR Transmitter Parameters ............................................................ 4-7
4.7.3
Galileo SAR Antennas ................................................................................... 4-7
5.
GLONASS 406 MHZ MEOSAR REPEATER ................................................................ 5-1
5.1
Glonass Overall Description ...................................................................................... 5-1
5.2
Glonass Repeater Functional Description .................................................................. 5-1
5.3
Glonass Repeater Operating Modes ........................................................................... 5-2
5.4
Glonass Repeater Spectrum Characteristics ............................................................... 5-2
5.5
Glonass Repeater Coverage Area ............................................................................... 5-3
5.6
Glonass Repeater Performance Parameters ................................................................ 5-3
5.6.1
Glonass SAR Receiver Parameters ................................................................ 5-4
5.6.2
Glonass SAR Transmitter Parameters ........................................................... 5-5
5.6.3
Glonass SAR Antennas .................................................................................. 5-5
6.
BDS 406 MHZ MEOSAR REPEATER ........................................................................... 6-1
6.1
BDS MEOSAR Overall Description .......................................................................... 6-1
6.2
BDS MEOSAR Functional Description ..................................................................... 6-1
6.3
BDS Repeater Operating Modes ................................................................................ 6-2
6.4
BDS Repeater Spectrum Characteristics .................................................................... 6-2
6.5
BDS Repeater Coverage Area .................................................................................... 6-3
6.6
BDS MEOSAR Repeater Performance Parameters ................................................... 6-3
6.7
BDS SAR Repeater Receiver Parameters .................................................................. 6-5
6.7.1
BDS SAR Repeater Bandpass Parameters ..................................................... 6-5
6.7.2
BDS MEOSAR Repeater Receive Antenna Pattern ...................................... 6-5
6.7.3
BDS MEOSAR Repeater Transmit Antenna Pattern ..................................... 6-6

LIST OF ANNEXES
ANNEX A: INFORMATION FOR MEOLUT OPERATORS ................................................... A-1
ANNEX B: MEOSAR SATELLITE TECHNICAL PARAMETERS ........................................ B-1
B.1
MEOSAR Satellite Identification Parameters ........................................................... B-1
B.2
RF Configuration of the MEOSAR satellites ............................................................ B-2
ANNEX C: MEOSAR ORBITAL DATA DESCRIPTION ......................................................... C-1
C.1
Introduction ............................................................................................................... C-1
C.2
Summary of available MEOSAR Satellite Orbital Data and Associated Accuracy
Performance ................................................................................................ C-1
C.3
Definitions ................................................................................................................. C-3
LIST OF FIGURES
Figure 3.1: DASS S-Band Downlink Spectrum Averaged ................................................................. 3-2
Figure 3.2: DASS S-Band Downlink Spectrum .................................................................................. 3-3
Figure 3.3: L-Band Output when Line-Stretcher was Connected to the Input of the SAR/GPS EQM.
.................................................................................................................................... 3-7
Figure 3.4: L-Band Output when Line-Stretcher was Connected to the L-Band Output of the SAR/GPS
EQM (Using a Coupler). ............................................................................................ 3-7
Figure 3.5: SAR/GPS Normalized Gain vs Downlink Frequency Offset ........................................... 3-9
Figure 4.1: Implementation of SAR Functions on the Galileo Satellites ............................................ 4-2
Figure 4.2: Galileo SAR Repeater L-Band Downlink Narrow-Band (50 kHz) Signal Spectrum ...... 4-4
Figure 4.3: Galileo SAR Repeater L-Band Downlink Normal Band (90 kHz) Signal Spectrum ....... 4-4
Figure 4.4: Galileo SAR Repeater Normal and Narrow Bandpass Filtering Performance ................. 4-7
Figure 4.5: SAR Rx Antenna Gain on Galileo IOV 419 Satellite (Four Cross-Sections) .................. 4-8
Figure 4.6: SAR Tx Antenna Gain on Galileo IOV 419 Satellite (Four Cross-Sections) .................. 4-8
Figure 4.7: SAR Rx Antenna Gain on Galileo FOC 426 Satellite (Four Cross-Sections) .................. 4-9
Figure 4.8: SAR Tx Antenna Gain on Galileo FOC 426 Satellite (Four Cross-Sections) .................. 4-9
Figure 5.1: Implementation of SAR Function on GLONASS Satellites ............................................ 5-2
Figure 5.2: SAR Repeater L-Band Downlink Normal Band Signal Spectrum ................................... 5-2
Figure 5.3: CS ID 503 Zero Degree Elevation Coverage Area........................................................... 5-3
Figure 5.4: Glonass-K2 SAR Repeater Normal Bandpass Filtering Performance ............................. 5-5
Figure 5.5: SAR Repeater Receiving Antenna Gain (Four Cross-Sections) ...................................... 5-5
Figure 5.6: SAR Repeater Transmitting Antenna Gain (Four Cross-Sections) .................................. 5-6
Figure 6.1: Structure of SAR Functions on the BDS Satellites .......................................................... 6-2
Figure 6.2: BDS MEOSARR Normal Band Spectrum Characteristics .............................................. 6-2
Figure 6.3: BDS MEOSARR Narrow Band Spectrum Characteristics .............................................. 6-3
Figure 6.4: BDS MEOSARR Normal and Narrow Bandpass Filtering Performance ........................ 6-5
Figure 6.5: SAR/BDS Rx Antenna Gain (Four Cross-Sections) ........................................................ 6-5
Figure 6.6: SAR/BDS Tx Antenna Gain (Four Cross-Sections) ........................................................ 6-6
Figure C.1: Latency and Validity Timeline ....................................................................................... C-4

LIST OF TABLES
Table 3-1: DASS S-Band SAR Receiver Parameters ......................................................................... 3-4
Table 3-2: DASS S-Band SAR Transmitter Parameters ..................................................................... 3-5
Table 3-3: Typical SAR/GPS Repeater Characteristics at Design...................................................... 3-8
Table 4-1: Keplerian Elements of Nominal Orbital Positions  for Galileo C/S 418 and C/S 414 Satellites
.................................................................................................................................... 4-1
Table 4-2: Typical Overall Repeater Gain at Reference Gain Step in FGM ...................................... 4-3
Table 4-3: Typical SAR/Galileo IOV Repeater Characteristics ......................................................... 4-5
Table 5-1: Orbital Parameters of SAR/GLONASS Satellites ............................................................. 5-1
Table 5-2: SAR Repeater Characteristics ........................................................................................... 5-3
Table 6-1: Keplerian Elements of Nominal Orbital Positions for BDS MEO Satellites with SAR
payload ....................................................................................................................... 6-1
Table 6-2: Typical SAR/BDS Repeater Design Characteristics ......................................................... 6-3
Table B-1: MEOSAR Satellite Identification Parameters ................................................................. B-1
Table B-2: Current RF Configuration of the MEOSAR Satellites .................................................... B-2
Table B-3: DASS S-Band Filter Settings ........................................................................................... B-4
Table B-4: Galileo Filter Settings ...................................................................................................... B-4
Table B-5: GPS L-Band Filter Settings (To Be Completed) ............................................................. B-4
Table B-6: Glonass L-Band Filter Settings ........................................................................................ B-4
Table B-7: BDS L-Band Filter Settings ............................................................................................. B-5
Table C-1: Parameters that Service Providers Are Intending to Provide ........................................... C-1

1-1

1.
INTRODUCTION
1.1
Overview
This document provides a description of the MEOSAR payloads carried on board these spacecraft.
1.2
Purpose
The purpose of this document is to describe the functionality and performance parameters for each
MEOSAR instrument.  The document is intended to be used to ensure the necessary compatibility for
the 406 MHz beacon to satellite uplink and compatibility for the satellite to MEOSAR local user
terminal (MEOLUT) downlink.  The document is not intended for use as a specification for
procurement of hardware for MEOSAR repeaters.
1.3
Scope
This document presents a technical description of the MEOSAR repeaters used in the Cospas-Sarsat
system. Section 2 provides a general overview of the MEOSAR repeater function.  Sections 3, 4 and 5
provide descriptions of the repeaters on the USA, European and Russian, satellites.
1.4
Reference Documents
The following documents contain useful information to the understanding of this document:
C/S R.012
Cospas-Sarsat 406 MHz MEOSAR Implementation Plan
C/S T.001
Specification for Cospas-Sarsat 406 MHz Distress Beacons
C/S T.011
Description of the Payloads used in the Cospas-Sarsat GEOSAR System
C/S T.018
Specification for Second-Generation Cospas-Sarsat 406-MHz Distress Beacons
C/S T.019
Cospas-Sarsat MEOLUT Specification and Design Guidelines
C/S T.020
Cospas-Sarsat MEOLUT Commissioning Standard
C/S G.003
Introduction to the Cospas-Sarsat System
C/S S.011
Cospas-Sarsat Glossary
- END OF SECTION 1

2-1

2.
406 MHZ MEOSAR SYSTEM DESCRIPTION
The Cospas-Sarsat MEOSAR Space Segment consists of SAR instruments on board satellites in
medium-earth orbit.  The SAR instruments are radio repeaters that receive distress beacon signals in
the 406 - 406.1 MHz band and relay these signals to MEOLUTs for processing beacon identification
and associated data.  A description of the Cospas-Sarsat beacon signal parameters and data protocols
is provided in reference document C/S T.001. MEOSAR instruments are flown on the following
satellites:
Spacecraft
Country/Organization
Status
Galileo
Europe
In Deployment
Glonass-K
Russia
In Deployment
GPS-II/III (DASS) USA
Non-operational; data available for operational use
GPS-III
USA/Canada
Planned
BDS-3
China (P.R. of)
Fully Deployed
Note: The DASS S-band constellation is not planned to be declared as operational, but its data may be
used operationally.
2.1
406 MHz MEOSAR Payload Functional Description
The DASS S-band SAR payload is carried on some GPS spacecraft and consists of an uplink 406 MHz
receive antenna, a search and rescue repeater (SARR) instrument and a transmit antenna. DASS
repeaters have a S-band downlink instead of the 1544-1545 MHz band assigned by the ITU.
The SAR/GPS L-band SAR payload is carried on GPS spacecraft and consists of an uplink 406 MHz
receive antenna, a search and rescue repeater (SARR) instrument and a transmit antenna. The SARR
instrument consists of a 406 MHz receiver and a frequency translator feeding a 1544 MHz downlink
transmitter.
The SAR/Galileo payload consists of the forward link 406 MHz receive antenna, transponder and a
1544 MHz transmit antenna, and a return link for SAR-related acknowledgements and other messages.
In terms of hardware, the return link is part of the Galileo ground mission segment (GMS) and
navigation payload.
The SAR/Glonass payload include a 406 MHz repeater on the K series (K-1 and K-2) of spacecraft to
relay the signals transmitted by 406 MHz distress beacons. Glonass K-2 series spacecraft are expected
to also include a return link capability.
The SAR/BDS payload consists of the forward link 406 MHz receive antenna, transponder and a
1544 MHz transmit antenna, and a return link for SAR-related acknowledgements and other messages
via BDS B2b signal.

2-2

2.2
MEOSAR Orbit Information
Satellite positions and other information are needed for location processing and are normally available
on the navigation message broadcast by each satellite. To provide redundancy, MEOSAR space
segment providers are establishing servers, which can be accessed over the Internet where the orbit
parameters would be available.
Annex C contains a table of what MEOLUT operators would like to see provided over the Internet
with projected accuracy and, in addition, a table of what data is intended to be provided on the space
segment providers’ servers. For completeness, information on the navigation messages is presented as
well.
2.3
MEOSAR Interoperability Parameters
Document C/S R.012 defines interoperability as follows: “the components of the MEOSAR system
conform to a common architecture and comply with agreed performance standards. A set of similar
satellite downlink characteristics allows MEOLUTs to track satellites and process signals from
interoperable MEOSAR constellations.”
Payload characteristics that had been identified in document C/S R.012 that impact MEOSAR
interoperability are refined as follows:
•
Modulation of the downlinks: non-inverted frequency translation will be used by all L
band constellations so there is no additional modulation of the downlink, except DASS
constellation, which inverts the spectrum. This simplified MEOLUT design.
•
Downlink frequency: MEOSAR satellite constellations need not have the exact same
downlink frequencies to enable MEOLUTs to process their downlinks. SAR/GPS L-
band will operate in the 1544.740 - 1544.840 MHz band, SAR/Glonass will operate in
the 1544.850 - 1545.950 MHz band, SAR/Galileo will operate in the 1544.050-
1544.150 MHz band and SAR/BDS will operate in the 1544.160-1544.260 MHz band.
These frequencies were chosen to avoid the 1544.5 MHz downlink of the GEOSAR
spacecraft. The GPS DASS S-band satellites use S-band 2226 MHz.
•
Downlink EIRP: MEOSAR providers have agreed that to ensure interoperability,
MEOSAR downlink EIRPs should exceed 15 dBW for all MEOLUT-to-satellite
elevation angles above 5 degrees.
•
Downlink polarization: circular. The design for SAR/GPS L-band is to operate with
RHCP downlinks, whereas SAR/Galileo and SAR/Glonass plan to operate LHCP
downlinks. The DASS S-band satellites operate with LHCP.
•
Repeater bandwidth: MEOSAR providers and Cospas-Sarsat have agreed that the
406 MHz L band SAR repeater bandwidth should be as follows (centered on
406.05 MHz):
o
80 kHz (1.0 dB bandwidth),
o
90 kHz (3.0 dB bandwidth),
o
< 110 kHz (10 dB bandwidth),
o
< 170 kHz (45 dB bandwidth),
o
< 200 kHz (70 dB bandwidth).

2-3

The bandwidth of the DASS S-band repeater is about 270 kHz, wider than the nominal
100 kHz, so filtering must be done on the downlink to remove the unwanted signals.
•
Repeater receiver G/T: MEOSAR providers and Cospas-Sarsat have agreed that a
repeater G/T value of -17.7 dB/K (assuming an antenna noise temperature of 400 K) or
greater would enable the development of a fully interoperable MEOSAR system that
satisfied the performance requirements for compatibility with Cospas-Sarsat.
•
System dynamic range: the repeater dynamic range and AGC characteristics determine
the MEOSAR system’s ability to adequately accommodate interference and varying
beacon message traffic loads. MEOSAR providers have agreed that the repeater
instantaneous linear range (not including AGC) should meet or exceed 30 dB.
•
Repeater AGC characteristics: range >30 dB with a time constant < 80 ms.
•
Repeater linearity: MEOSAR providers have agreed that the ratio of power from a
relayed beacon to intermodulation products should be greater than 30 dBc when the
repeater is operating beyond its linear range.
•
Repeater group delay: repeater group delay characteristics impact upon MEOLUT
time-tagging accuracy and, consequently, MEOSAR independent location accuracy
performance. To ensure that minimum performance requirements are satisfied
regardless of the satellite constellation relaying the beacon signal, MEOSAR providers
agreed that repeater group delay variation with frequency should be less than 10 µs in
any 4 kHz anywhere within the 1 dB bandwidth. These variations are valid only for in-
orbit nominal operational temperature ranges as determined by the respective space
segment operators.
•
Group delay stability: to ensure negligible impact on TOA/TDOA estimation and
effective exchange of TOA data, the MEOSAR providers agreed to a group delay
stability with respect to all environmental conditions and ageing with a stability within
that range of 500 nanoseconds.
•
Uplink polarization: SAR/GPS L-band, SAR/Galileo and SAR/Glonass will all use
RHCP with an axial ratio < 2.5 dB over the Earth coverage as the uplink polarization,
while DASS S-band uses LHCP as the uplink polarization.
The following satellite parameters are suggested as enhancements that can be considered by space
segment providers to possibly enhance system performance:
•
Repeater bandwidth: to reduce the impact of side-band interferers, the 406 MHz L-
band SAR repeater bandwidth should be as follows (centered on 406.05 MHz):
o
90 kHz (1.0 dB bandwidth),
o
< 100 kHz (10 dB bandwidth),
o
< 170 kHz (45 dB bandwidth),
o
< 200 kHz (70 dB bandwidth).
•
Repeater bandpass characteristics: to ensure low distortion of the second generation
beacon signals, the maximum SAR payload L-band signal amplitude ripple should be
± 0.5 dB (i.e., 1 dB peak to peak) over any 1 kHz within the 80 kHz passband, and the
maximum overall amplitude ripple should be ± 1.25 dB (i.e., 2.5 dB peak to peak)
within the entire 80 kHz passband.
•
Repeater group delay: repeater group delay variation with frequency should be within
± 10 μs in ± 28 kHz band from the center frequency of the 1 dB bandwidth.

2-4

•
Group delay stability: group delay stability with respect to environmental conditions
within the 1 dB bandwidth of < 200 ns peak-to-peak in the medium term (i.e., over any
3 minutes) and < 400 ns peak-to-peak over any 24 hours (i.e., long term).
- END OF SECTION 2 -

3-1

3.
GPS 406 MHZ MEOSAR REPEATER
3.1
DASS S-Band
DASS S-Band satellites have been on orbit since 2002 and have provided MEOSAR satellite
functionality that has been vital to the development of the MEOSAR system, including ground system
development and testing of MEOLUTs and MCCs. They were used extensively for the Proof of
Concept and the Demonstration and Evaluation phases of MEOSAR system development and testing.
They will be replaced as part of the normal GPS constellation replenishment with SAR/GPS MEOSAR
satellites that carry a SAR/GPS payload specifically designed for Cospas-Sarsat and delivered to the
GPS program from the Canadian Department of National Defence.
The DASS S-band constellation’s data may be used operationally. The USA will commission DASS
satellites in order to document their performance and support their use as needed. The capability to use
the DASS S-band satellites is not required but the SAR payloads are available for continued support
of the MEOSAR system development, operations and interference monitoring, as long as they remain
in operation.
3.1.1
DASS S-Band Overall Description
DASS satellites contain a non-regenerative repeater that only amplifies, translates in frequency, and
retransmits the received beacon message.
The DASS payload will transmit an RF spectrum centered at approximately 1.022 MHz below a center
frequency of 2227.494 MHz.  The center frequency is being very accurately derived from a phase-
lock-loop that is governed by the on board GPS rubidium clock.
•
Polarization: Left Hand Circular
•
Center Frequency: 2227.494265 MHz
•
Carrier Stability: + 0.022 Hz (1 part in 1011)
•
Maximum Doppler shift: + 5.7 kHz
The DASS satellite RF spectrum is centered at approximately 1.022 MHz below the center frequency
of 2227.494 MHz and is, therefore centered at 2226.472 MHz and has a double-sided -3dB bandwidth
of approximately 220 kHz.
The downlink from each satellite contains a copy of the beacon message that has been translated from
UHF to S-band according to the following formula.
Downlink frequency = 2226.472340 MHz + 406.05 MHz - UHF uplink frequency
The SV UHF receiver has a band pass filter with a -3 dB bandwidth of 220 kHz.  The transmitted
power is set at 0.6 W and is shared between all signals and in-band noise detected by the UHF receiver.
The total transmitted S-band EIRP at bore sight is 10 dBW.

3-2

S-band GPS satellites, also known as DASS satellites, carrying MEOSAR repeaters acquire Cospas-
Sarsat designations according to their unique two-digit Space Vehicle ID number (SVID), by preceding
the SVID by the number 3.
The satellites listed in Table B-2 carry a repeater suitable for SAR use.  Future GPS satellite launches
will provide the DASS capability until it is replaced by the SAR/GPS capability, so the list of available
satellites will continue to grow and be updated.
The GPS satellites are in six orbital planes with four satellites each. The six orbit planes have
approximately 55° inclination and are separated by 60° right ascension of the ascending node (angle
along the equator from a reference point to the orbit's intersection). Reference orbital positions for
nominal MEOSAR GPS S-band satellites can be found in Annex A of this document.
3.1.2
DASS S-Band Repeater Functional Description
The DASS repeater can only be operated in the Automatic Gain Control (AGC) mode.
3.1.3
DASS S-Band Repeater Operating Modes
The DASS repeater can only be operated in the Automatic Gain Control (AGC) mode.
3.1.4
DASS S-Band Repeater Spectrum Characteristics
The following spectrum photographs show the downlink spectrum of a typical DASS satellite. The
signals seen are other signals within the repeaters 220 kHz band, but outside of the 100 kHz SAR band.
Both photographs were taken with a real time spectrum analyser.
Figure 3.1: DASS S-Band Downlink Spectrum Averaged

![Image 1 from page 13](/images/cospas-sarsat/T-series/T016/T016_page_13_img_1.png)

3-3

Figure 3.2: DASS S-Band Downlink Spectrum
3.1.5
DASS S-Band Repeater Coverage Area
The DASS S band repeater is designed to cover the full visible Earth’s disc both in the uplink and in
the downlink. The difference in the path loss between satellites seen on the horizon and those appearing
in zenith is 1.9 dB.
3.1.6
DASS S-Band Repeater Performance Parameters
The following data is derived from the on-orbit DASS Commissioning Tests, conducted by the USA
in 2014-2016.
A statistical analysis was performed on the data as follows:
1. When multiple measurements were made on one satellite, the results were averaged to get a
single reportable result. If one measurement was done, then the reported result is that one
measurement.
2. The range of the reported results for all tested satellites are given.
3. The overall average, calculated by taking the reported results for each satellite and averaging
them.
4. A standard deviation calculated by taking the reported results from each satellite and finding
the standard deviation.

![Image 1 from page 14](/images/cospas-sarsat/T-series/T016/T016_page_14_img_1.png)

3-4

3.1.6.1 DASS S-Band SAR Receiver Parameters
Table 3-1: DASS S-Band SAR Receiver Parameters
Parameter
Interoperability
Requirement
DASS On Orbit Performance
Unit
Uplink frequency range
406.0 to 406.1
405.915 to 406.185
MHz
Receive centre frequency
Normal mode
406.050
406.050
MHz
Nominal input power at antenna
-159.0
-
dBW
Maximum input power at antenna
-148.0
dBW
System dynamic range

Range: 26 to 37
Average: =30.9
Standard Deviation: =4
dB
Receive antenna polarisation
RHCP
LHCP
Receive antenna gain at boresight and EoC
13.5 (boresight)
11.6 (EoC)
dBi
Receive antenna axial ratio
< 2.5
Not measured on orbit
dB
Satellite G/T
At edge of coverage
At centre of coverage
>-17.7
Range: -29.6 to -16
Average: = -21.46
Standard Deviation: = 3.3
dB/K
System noise temperature
K
Bandpass characteristics
Normal mode
> 80 kHz (1.0 dB)
> 90 kHz (3.0 dB)
< 110 kHz (10 dB)
< 170 kHz (45 dB)
< 200 kHz (70 dB)
220 kHz (3 dB)
Phase linearity (overall in-band)
Normal mode
/
degree
Group delay (turn-around time)
Normal mode
/
s
Group delay uncertainty (95% conf.)

ns
Group delay over 4 kHz (slope)
Normal mode

s/4kHz
Transponder gain modes
ALC time constant
< 80
ms
ALC dynamic range
> 30
Range: 26 to 37
Average = 30.9
Standard deviation = 4
dB
Transponder gain (multiple measurements
on each sat averaged first)
> 180
Range: 151-159.4
Average = 156.27
Standard Deviation = 1.94
dB
Fixed gain mode adjustment range
dB
Transponder gain at nominal o/p power
dB

3-5

Parameter
Interoperability
Requirement
DASS On Orbit Performance
Unit
Transponder linearity1
> 30
In-Band
Range: 31 to 36
Average = 33.47
Standard Deviation = 1.81
Out of band: None Seen
dBc
Translation frequency
Hz
Frequency translation
Accuracy
Short term stability (100 ms)
± 2 x 10-11
1 x 10-11
Accuracy ≤ 8.7 x 10-9
Average Accuracy = 8 x 10-10
Error range=: -22 to 8 Hz
Error average = 2.1 Hz
Error Standard Deviation = 8.8 Hz
Gain variation
dBpk-pk
Translation frequency stability
Table 3-2: DASS S-Band SAR Transmitter Parameters
Parameter
Interoperability
Requirement
DASS Performance
Units
Downlink frequency band
2226.47229 to 2226.47239 (SAR band)
2226.472205 to 2226.472475 (repeater)
MHz
Downlink centre frequency
Normal mode
2226.47234
MHz
Downlink antenna polarisation
LHCP
Transmit antenna axial ratio
dB
Downlink EIRP
15 dBW
Range: 27 to 34.3
Average = 30.3
Standard Deviation = 2.1
dBm
EIRP stability in ALC mode
dBpk-pk
EIRP stability in FG mode
dBpk-pk
In band Intermod Products
Range: 31 to 36 dB below two tones level
Average = 33.47
Standard Deviation = 2.1
dB
Out of band Intermod products
None seen
3.2
GPS-III L-Band
The SAR/GPS L-band payloads hosted on the GPS-IIIF Space Vehicles will replace the DASS S-band
constellation as the normal GPS constellation replenishment for the Cospas-Sarsat MEOSAR system.
These payloads were designed by the Canadian Department of National Defence, and the Space
Vehicles hosting these payloads were built by United States Space Force, Space and Missile Systems
Center.
1  In-band measured via spectrum analyzer using two tones and comparison of the difference between the
intermodulation products and the two tones.

3-6

The SAR/GPS L-band payloads are to be launched starting in 2026. The information presented in this
section refers to the data presented at the Critical Design Review (CDR) of the SAR/GPS repeaters
completed in 2022.
3.2.1
GPS III Overall Description
The SAR/GPS L-band repeater payloads will receive distress beacon signals in the 406-406.1 MHz
band (UHF) and relay these signals at the centre frequency of 1544.79 MHz (L-band) over a 150 kHz
bandwidth to the MEOLUT for processing beacon identification and location.
The GPS constellation will comprise of 22 GPS-IIIF satellites equipped with the SAR/GPS L-band
repeater payloads. Once launched, these payloads will be commissioned jointly by the USA and
Canada.
3.2.2
GPS III Repeater Functional Description
The SAR/GPS L-band repeater payloads will provide a near-real-time “bent-pipe” SAR function for
the detection and location of both the first and second generation of compliant 406 MHz distress
beacons but will not have the ability to perform a Return Link Service function. The payload will use
the GPS-IIIF Space Vehicle provided uplink antenna (D1) to receive beacon signals, the L-band
downlink (L6) antenna for transmission and a single 10.23 MHz sine wave reference clock signal for
the generation of all local oscillators used in the frequency translation.
To ensure compatibility and interoperability across the MEOSAR system, the SAR/GPS L-band
repeater payloads were designed based on the MEOSAR space segment interoperability requirements
as defined in section 2.3 of this document. Its design utilizes an analog double conversion bent pipe
repeater concept and applies frequency translation without frequency inversion. The repeater does not
demodulate or add new modulation to the uplink signals. Being an analog system, it does not use any
programmable digital components, non-volatile memory or associated software or firmware. The
repeater uses a cascaded down-conversion and up-conversion to convert the cross-band UHF to L-band
frequencies, by first down-converting the UHF D1 uplink to a nominal intermediate frequency (IF)
and then up-converting the IF to the L-band L6 signal while providing a constant output power over
the dynamic range. The repeater then uses an output L-band filter to perform the output signal filtering
(i.e., rejection of amplified thermal noise and up-conversion mixing products for the protection of the
radio-astronomy frequency bands) and ensures a low loss path for the downlink signal before sending
it to the L6 downlink antenna.
3.2.3
GPS III Repeater Operating Modes
The SAR/GPS L-band repeater will operate in Automatic Level Control (ALC) mode but not in a Fixed
Gain Mode (a feature that is only available during factory alignment and acceptance testing phases).
On orbit, the repeater will therefore operate in a fixed set-point automatic gain control (AGC) mode
that will preserve SNR and linearity over the input dynamic range.
The SAR/GPS L-band repeater accepts a pulse discrete ON and OFF command from the GPS-IIIF SV
to turn the repeater ON or OFF. Therefore the operational modes of the SAR/GPS repeater are: ON
mode and OFF mode. It also exchanges other active analog telemetry and passive temperature
telemetry signals with the GPS-IIIF Space Vehicle that are downlinked to the GPS control segments
for health and status monitoring by the SAR/GPS space segment providers.

3-7

The SAR/GPS L-band repeater will only operate in the normal (90 kHz) bandwidth mode as it does
not have a narrow (50 kHz) bandwidth mode.
3.2.4
GPS III Repeater Spectrum Characteristics
The L-band spectrum characteristics for the SAR/GPS Engineering Qualification Model (EQM) during
its CDR are shown in Figure 3.3 and Figure 3.4. These outputs were captured from the spectrum
analyzer (by keeping it in maximum hold while the line-stretcher was traversed) when connected to
the input and output of the EQM respectively.
Figure 3.3: L-Band Output when Line-Stretcher was Connected to
the Input of the SAR/GPS EQM.
Figure 3.4: L-Band Output when Line-Stretcher was Connected to
the L-Band Output of the SAR/GPS EQM (Using a Coupler).

![Image 1 from page 18](/images/cospas-sarsat/T-series/T016/T016_page_18_img_1.png)

![Image 2 from page 18](/images/cospas-sarsat/T-series/T016/T016_page_18_img_2.png)

3-8

3.2.5
GPS III Repeater Coverage Area
The SAR/GPS L-band repeater is designed to cover the full visible Earth’s disc both in the uplink and
in the downlink.
3.2.6
GPS III Repeater Performance Parameters
Table 3-3 presents the typical measured satellite payload (SAR/GPS EQM) performances based on
ground testing at the time of SAR/GPS CDR.
Table 3-3: Typical SAR/GPS Repeater Characteristics at Design
Parameter
Interoperability
Requirement(a)
SAR/GPS Design
Performance
Unit
Uplink frequency range
406.0 to 406.1
406.0 to 406.1
MHz
Receive centre frequency
406.050
406.050
MHz
Nominal input power at antenna
-159.0
-165.0
dBW
Maximum input power at antenna
-148.0
-135.0
dBW
System dynamic range


dB
Receive antenna polarization
RHCP
RHCP
Receive antenna gain
TBC(g)
dBi
Receive antenna axial ratio
< 2.5
Not measured
dB
Satellite G/T (b)
At edge of coverage (c)
At centre of coverage
>-17.7
>-17.7(h)
dB/K
System noise temperature (d)
TBC
K
Bandpass characteristics
Normal mode
> 80 kHz (1.0 dB)
> 90 kHz (3.0 dB)
< 110 kHz (10 dB)
< 170 kHz (45 dB)
< 200 kHz (70 dB)
> 80 kHz (1.0 dB)
> 95 kHz (3.0 dB)
< 110 kHz (10 dB)
< 150 kHz (45 dB)
< 200 kHz (70 dB)
Group delay uncertainty (95% conf.)


ns
Group delay over 4 kHz (e) (slope)

< 8
s/4 kHz
Transponder gain modes
ALC
ALC time constant
< 80
45 - 63
ms
ALC dynamic range
> 30

dB
Transponder gain
> 180
> 180(h)
dB
Transponder linearity (C/I3)
> 30

dBc
Translation frequency
1,138,733,300.0
Hz
Frequency translation
Accuracy
Short term stability (100 ms)
± 2 x10-11
1 x10-11
< ±2 x10-11
0.5 x10-11
Gain variation (f)
TBC
dBpk-pk
Translation frequency stability
TBC
Downlink frequency band
1,544.715 to 1,544.865
MHz
Downlink centre frequency
1,544.79
MHz
Downlink antenna polarization
RHCP
Transmit antenna axial ratio
TBC
dB

3-9

Parameter
Interoperability
Requirement(a)
SAR/GPS Design
Performance
Unit
Downlink EIRP

TBC
dBW
EIRP stability in ALC mode
TBC
dBpk-pk
(a)
MEOSAR space segment interoperability requirements.
(b)
G/T as measured in orbit. The MEOSAR space segment interoperability requirement is defined
assuming antenna external noise temperature Ta = 400 K.
(c)
The receive antenna edge of coverage is defined at a beacon elevation angle of 5°.
(d)
System temperature computed at transponder input.
(e)
In the 1 dB band.
(f)
Gain variation in any 3 kHz within the operating band.
(g)
Space Vehicle parameter to be provided when available.
(h)
Value as determined by design.
3.2.6.1 GPS III SAR Receiver Parameters
The SAR/GPS repeater receive parameters are specified in Table 3-3.
3.2.6.2 GPS III SAR Transmitter Parameters
The SAR/GPS repeater transmit parameters are specified in Table 3-3. The bandpass characteristics
and transmitter bandwidths for the SAR/GPS repeater is presented in Figure 3.5 for the normal
(90 kHz) band. The typical normalized gain value was measured as 134.2 dB.
Figure 3.5: SAR/GPS Normalized Gain vs Downlink Frequency Offset

![Image 1 from page 20](/images/cospas-sarsat/T-series/T016/T016_page_20_img_1.png)

3-10

3.2.6.3 GPS III SAR Antennas
(to be provided later)
- END OF SECTION 3 -

4-1

4.
GALILEO 406 MHZ MEOSAR REPEATER
4.1
Galileo Overall Description
Galileo satellites carrying MEOSAR repeaters acquire Cospas-Sarsat designations according to their
unique two-digit Space Vehicle ID number (SVID), by preceding the SVID by number 4.
The information presented in this section refers to the Galileo In-Orbit Validation (IOV) satellites and
to FOC (Full Operational Capability) satellites.
Only two of four Galileo IOV satellites are equipped with SAR repeaters. These two satellites are
designated as Cospas-Sarsat 419 (GSAT0103, SVID-19) and Cospas-Sarsat 420 (GSAT0104,
SVID 20).
SAR/Galileo FOC satellites are currently under deployment and they are all equipped with SAR
Repeaters.
SAR/Galileo IOV and FOC satellites are in Walker 24/3/1 orbital configuration, with the slots
separated by 45 degrees. Reference orbital positions for nominal MEOSAR Galileo satellites2 can be
found in:
http://www.gsc-europa.eu/system-status/orbital-and-technical-parameters
Note that satellites Cospas-Sarsat 418 (GSAT0201, SVID-18) and Cospas-Sarsat 414 (GSAT0202,
SVID-14) are exceptionally in elliptical orbits. Their orbital positions, represented by Keplerian
elements for the reference time 1 October 2010 at 00:00:00 UTC, are defined in Table 4-1.
Table 4-1: Keplerian Elements of Nominal Orbital Positions
for Galileo C/S 418 and C/S 414 Satellites
Satellite
Semi-Major
Axis
(km)
Launch
date
Eccentricity
Inclination
(deg)
RAAN
(deg)
Arg.
Perigee
(deg)
True
Anomaly
(deg)
S VID
Slot
GSAT0201

NA
27977.69
22.08.2014
1.57E-01
49.97
70.106
41.121
137.250
GSAT0202

NA
27977.61
22.08.2014
1.57E-01
50.03
69.080
42.294
317.263
Note: The coordinate reference frame used is CIRS3 (true equator).
The following sections provide information regarding the repeater configuration, modes of operation,
and performance characteristics, including group delay characteristics, as recommended by CSC-47.
2 Nominal MEOSAR Galileo satellites: SAR/Galileo Satellites for which ephemeris are available either through signal
in space or through the Galileo Service Centre Server
3  Dennis D. McCarthy and Gérard Petit (eds.), “IERS CONVENTIONS (2003)” IERS Convention Centre.

4-2

4.2
Galileo Repeater Functional Description
4.2.1
Payload Configuration
The Galileo satellite has two functional elements relevant to SAR, performing two principal functions
pertaining to the SAR/Galileo system: the Navigation Function and the SAR Function. SAR/Galileo
utilises both of these elements: the SAR Function for performing of the Forward Link Alert Service
and the Navigation Function for performing the Return Link Service.
Figure 4.1 depicts the implementation of the two Galileo SAR functions. This section deals with the
SAR Repeater, which performs the Forward Link Alert Service function, and comprises the SAR
Transponder (SART) and SAR receive and transmit antennas (SARANT).
Figure 4.1: Implementation of SAR Functions on the Galileo Satellites
4.2.2
Configuration of Galileo SAR Repeaters
The Galileo SAR repeaters are based on bent pipe type transponders with no frequency inversion. They
receive signals at the 406 MHz band and retransmit in the L6 band at 1.5441 GHz (see Table 4-3).
They are designed according to the space segment interoperability requirements4, ensuring MEOSAR
compatibility and interoperability.
4.3
Galileo Repeater Operating Mode
The Galileo repeater can operate in two gain and two bandwidth modes. The operational modes include
the normal (90 kHz) and narrow (50 kHz) bandwidth modes, as well as the possibility to operate with
adjustable Fixed Gain (FGM) or Automatic Level Control (ALC) mode. The operational modes of the
SAR repeater are therefore:
4 As defined in Annex F of document C/S R.012.

![Image 1 from page 23](/images/cospas-sarsat/T-series/T016/T016_page_23_img_1.png)

4-3

ON mode
•
ALC (transponder gain is self-regulated to ensure stable EIRP)
−
90 kHz BW (normal bandwidth mode): ALC90 (default mode)
−
50 kHz BW (narrowband mode): ALC50
In automatic level control gain mode the operational gain is automatically adjusted to obtain a power
of 7 dBW (IOV) or 6 dBW (FOC) at the output of the SAR transponder.
•
FGM (fixed gain, set by telecommand)
−
90 kHz BW (normal bandwidth mode): FGM90
−
50 kHz BW (narrowband mode): FGM50
In fixed gain mode (FGM) the operational gain is set by telecommand in a 31 dB range, with nominal
step of 1 dB. The range is adjusted so that when the transponder is in the 90 kHz bandwidth mode, and
at the input of the repeater there is only thermal noise, the nominal output power of 7 dBW (IOV) or
6 dBW (FOC) is achieved when the gain setting is set at the reference step.
The overall gain of the SAR repeater in the nominal gain setting in FGM (including the gains of the
receive and transmit antennas) is given in the table below.
Table 4-2: Typical Overall Repeater Gain at Reference Gain Step in FGM
FGM
Edge of coverage
182 dB
Centre of coverage
187 dB
STANDBY mode (transponder is powered up, but RF power is OFF)
OFF mode (transponder is not powered)
4.4
Galileo Repeater Spectrum Characteristics
The downlink spectrum of the Galileo repeaters is dominantly shaped by the intermediate-frequency
crystal filters which define the pass band. Figure 4.2 and Figure 4.3 represent an example of the Galileo
SAR repeater L-band downlink signal spectrum in narrow- and normal- bandwidth setting.

4-4

Figure 4.2: Galileo SAR Repeater L-Band Downlink Narrow-Band (50 kHz) Signal Spectrum
Figure 4.3: Galileo SAR Repeater L-Band Downlink Normal Band (90 kHz) Signal Spectrum
4.5
Galileo Repeater Coverage Area
The Galileo SAR repeater is designed to cover the full visible Earth’s disc both in the uplink and in the
downlink. From the orbital altitude of the Galileo constellation the visible Earth disc covers
approximately 39.2% of Earth’s surface. The difference in the path loss between satellites seen on the
horizon and those appearing in zenith is 1.9 dB.

![Image 1 from page 25](/images/cospas-sarsat/T-series/T016/T016_page_25_img_1.png)

![Image 2 from page 25](/images/cospas-sarsat/T-series/T016/T016_page_25_img_2.png)

4-5

4.6
Galileo Repeater Performance Parameters
Table 4-3 presents the typical measured satellite payload performances based on in-orbit and on ground
equipment testing.
Table 4-3: Typical SAR/Galileo IOV Repeater Characteristics
Parameter
Interoperability
Requirement(a)
Galileo IOV
Performance
Galileo FOC
Performance
Unit
Uplink frequency range
406.0 to 406.1
406.0 to 406.1
MHz
Receive centre frequency
Normal mode
Narrowband mode
406.050
406.043
406.050
406.043
MHz
Nominal input power at antenna
-159.0
-
dBW
Maximum input power at antenna
-148.0
-153.0
dBW
System dynamic range


dB
Receive antenna polarisation
RHCP
RHCP
Receive antenna gain at EoC (b)
11.7
dBi
Receive antenna axial ratio
< 2.5
< 1.8
dB
Satellite G/T (c)
At edge of coverage (a)
At centre of coverage
>-17.7
> -14.9
> -12.6
> -15.3
> -13.6
dB/K
System noise temperature (c, d)


K
Bandpass characteristics
Normal mode
Narrowband mode
> 80 kHz (1.0 dB)
> 90 kHz (3.0 dB)
< 110 kHz (10 dB)
< 170 kHz (45 dB)
< 200 kHz (70 dB)
> 50 kHz (1.0 dB)
< 75 kHz (10 dB)
< 130 kHz (45 dB)
< 160 kHz (70 dB)
> 80 kHz (10 dB)
> 95 kHz (3 dB)
< 110 kHz (10 dB)
< 150 kHz (45 dB)
< 200 kHz (70 dB)
> 50 kHz (1.0 dB)
< 70 kHz (10 dB)
< 100 kHz (45 dB)
< 180kHz (70 dB)
> 80 kHz (1.0 dB)
> 90 kHz (3 dB)
< 110 kHz (10 dB)
< 150 kHz (45 dB)
< 180 kHz (70 dB)
> 50 kHz (1.0 dB)
< 75 kHz (10 dB)
< 110 kHz (45 dB)
< 130 kHz (70 dB)
Phase linearity (overall in-band)
Normal mode
Narrowband mode
/
/


/
/
degree
Group delay (turn-around time) (e)
Normal mode
Narrowband mode
/
/


s
Group delay uncertainty (95% conf.)

< 150
< 163
ns
Group delay over 4 kHz (f) (slope)
Normal mode
Narrowband mode


2.5
3.5
s/4kHz
Transponder gain modes
FGM
ALC
ALC time constant
< 80


ms
ALC dynamic range
> 30

dB
Transponder gain
> 180
165 - 187
dB
Fixed gain mode adjustment range

(FGM: -1… +30)

(FGM: +1…+31)
dB
Transponder gain at nominal o/p
power

dB
Transponder linearity (C/I3)
> 30


dBc

4-6

Parameter
Interoperability
Requirement(a)
Galileo IOV
Performance
Galileo FOC
Performance
Unit
Translation frequency
1,138,050,000.0
1,138,049,997.6
Hz
Frequency translation
Accuracy
Short term stability (100 ms)
± 2 x10-11
1 x10-11
< ±2 x10-11
2 x10-11
< ±1 x10-12
4 x10-12
(h)
Gain variation (g)
0.3
dBpk-pk
Translation frequency stability
RAFS: < 1.0 x10-11
PHM: < 1.0 x10-14
Downlink frequency band
1,544.0 to 1,544.2
MHz
Downlink centre frequency
Normal mode
Narrowband mode
1,544.100
1,544.093
MHz
Downlink antenna polarisation
LHCP
Transmit antenna axial ratio
< 1.7
< 1.9
dB
Downlink EIRP

> 18.7 (i)
< 20.3 (j)
> 17.8 (i)
< 19.5(j)
dBW
EIRP stability in ALC mode
0.3
dBpk-pk
EIRP stability in FG mode
1.5
1.2
dBpk-pk
(a)
MEOSAR space segment interoperability requirements.
(b)
The receive antenna edge of coverage (EoC) is defined at a beacon elevation angle of 5°.
(c)
G/T as measured in orbit. The MEOSAR space segment interoperability requirement is
defined assuming antenna external noise temperature Ta = 400 K.
(d)
System temperature computed at transponder input.
(e)
These values refer to the center frequency. The full characterization of each launched SAR
payload with respect to delay is reported in accordance with the format proposed in document
C/S R.018.
(f)
In the 1 dB band.
(g)
Gain variation in any 3 kHz within the operating band.
(h)
Depending on the configuration settings of the on-board clocks may be significantly better.
(i)
In ALC mode or in FGM at nominal gain setting, over full Earth disc, including pointing
error.
(k)
In ALC mode or in FGM at nominal gain setting, at the centre of the beam (boresight).
4.7
Galileo SAR Receiver Parameters
SAR/Galileo receiver parameters are specified in Table 4-3.
4.7.1
Galileo SAR Bandpass Parameters
Bandpass characteristics of the Galileo transponders are presented in Figure 4.4 for both the normal
(90 kHz) and the narrow (50 kHz) bands. These are typical values, considering that there are small
variations with temperature and from unit to unit.

4-7

Figure 4.4: Galileo SAR Repeater Normal and Narrow Bandpass Filtering Performance
4.7.2
Galileo SAR Transmitter Parameters
SAR/Galileo transmitter parameters are specified in Table 4-3.
4.7.3
Galileo SAR Antennas
As an example of the Galileo IOV satellites, Figure 4.5 and Figure 4.6 show the SAR UHF receive and
L-band transmit antenna co-polar gain plots on Galileo IOV 419 satellite in four characteristic cross-
sections.

![Image 1 from page 28](/images/cospas-sarsat/T-series/T016/T016_page_28_img_1.png)

4-8

Figure 4.5: SAR Rx Antenna Gain on Galileo IOV 419 Satellite (Four Cross-Sections)
Figure 4.6: SAR Tx Antenna Gain on Galileo IOV 419 Satellite (Four Cross-Sections)
As an example of the Galileo FOC satellites Figure 4.7 and Figure 4.8 show the SAR UHF receive and
L-band transmit antenna co-polar gain plots of Galileo FOC 426 satellite in four characteristic cross-
sections.

![Image 1 from page 29](/images/cospas-sarsat/T-series/T016/T016_page_29_img_1.png)

![Image 2 from page 29](/images/cospas-sarsat/T-series/T016/T016_page_29_img_2.png)

4-9

Figure 4.7: SAR Rx Antenna Gain on Galileo FOC 426 Satellite (Four Cross-Sections)
Figure 4.8: SAR Tx Antenna Gain on Galileo FOC 426 Satellite (Four Cross-Sections)
- END OF SECTION 4 -


Gain [dBi]
Off-nadir angle [°]
phi = 0
phi = 45
phi = 90
phi = 135


Gain [dBi]
Off-nadir angle [°]
phi = 0
phi = 45
phi = 90
phi = 135

5-1

5.
GLONASS 406 MHZ MEOSAR REPEATER
5.1
Glonass Overall Description
The GLONASS satellites are located in middle circular orbit at 19,100 km altitude with a
64.8° inclination and a period of 11 hours and 15 minutes. The constellation operates in three orbital
planes, with eight evenly spaced satellites on each. A fully operational constellation with global
coverage consists of 24 satellites.
Installation of the search and rescue payload on a GLONASS satellite is subject to a national decision.
At this time, two GLONASS spacecraft series are among those that may be equipped with a SAR
payload: Glonass-K1 and Glonass-K2.
Table 5-1 details the launch dates, orbital position, other officially recognized names and additional
information of the SAR/GLONASS satellites currently in orbit.
Table 5-1: Orbital Parameters of SAR/GLONASS Satellites
Cospas-
Sarsat
identifier
Launch date
Satellite
vehicle
number5
Satellite
series
Satellite name
Other names
Norad ID
Orbital slot

26.02.2011

Glonass-K1
Cosmos-2471
Glonass-K1-11L
De-commissioned from the
GLONASS constellation, cannot be
used in Cospas-Sarsat

01.12.2014

Cosmos-2501
Glonass-K1-12L

2/9

25.10.2020

Cosmos-2547
Glonass-K1-15L

2/11

07.07.2022

Cosmos-2557
Glonass-K1-16L

3/22
In
total,
Glonass-K1
series
will
comprise
six
SAR/GLONASS
satellites
(including
decommissioned 501); subsequent SAR/GLONASS satellites will be Glonass-K2 series spacecraft.
The following sections provide information regarding the repeater description, modes of operation and
performance characteristics.
5.2
Glonass Repeater Functional Description
The SAR repeater is based on bent pipe type transponder with no frequency inversion. It receives
signals in the 406 – 406.1 MHz band and retransmits in the L-band centered at 1,544.9 MHz. The
transponder consists of two identical redundant configurations, 1st and 2nd.
The Glonass-K2 series satellites have two functional elements relevant to Cospas-Sarsat: the SAR
Function, for performing of the Forward Link Alert Service, and the Return Link Service.
5 The “satellite vehicle number” or “RF channel” value may be used to cross-reference the satellite IDs in Cospas-
Sarsat and national numeration system. For further details please visit https://www.glonass-iac.ru/en/sostavOG/

5-2

Figure 5.1: Implementation of SAR Function on GLONASS Satellites
5.3
Glonass Repeater Operating Modes
The SAR repeater can operate in one gain and two bandwidth modes. The operational modes include
the Normal and Narrow Bandwidth modes, the latter not being used. The Glonass-K2 repeater can
operate in one gain and one bandwidth mode (Normal). Repeater gain is self-regulated by Automatic
Gain control (AGC). The repeater gain is automatically adjusted to obtain a power of 7 dBW at the
output of the SAR transponder.
5.4
Glonass Repeater Spectrum Characteristics
Figure 5.2 depicts an example of the SAR repeater L-band downlink signal spectrum in normal-
bandwidth setting.
Figure 5.2: SAR Repeater L-Band Downlink Normal Band Signal Spectrum

![Image 1 from page 32](/images/cospas-sarsat/T-series/T016/T016_page_32_img_1.png)

![Image 2 from page 32](/images/cospas-sarsat/T-series/T016/T016_page_32_img_2.png)

5-3

5.5
Glonass Repeater Coverage Area
Figure 5.3 depicts the example of 0˚ elevation coverage area for SAR/GLONASS satellite C/S ID 503
crossing the equator.
Figure 5.3: CS ID 503 Zero Degree Elevation Coverage Area
5.6
Glonass Repeater Performance Parameters
Table 5-2 details typical satellite payload performance based on in-orbit and on ground equipment
testing assessments. The performance information was grouped by satellites where possible in order to
better represent the variety in design and to better serve the informational needs of ground segment
providers and the purposes related to space segment commissioning.
Table 5-2: SAR Repeater Characteristics
Parameter
Unit
Value
Interoperability
Requirement
Glonass-K1
(СS ID 502)
Glonass-K1
(C/S ID 503, 504)
Glonass-K2
Uplink frequency range
MHz
406.0 to 406.1
406.0 to 406.1
Receive centre frequency:
Normal mode
Narrowband mode
MHz
406.050
406.043
406.05
406.043
406.05
N/A
Maximum input power at
antenna
dBW
-
-153.0
System dynamic range
dB
> 30

Receive antenna polarization
RHСP
RHCP
Receive antenna gain at:
edge of coverage (EoC)(1)
centre of coverage (EoC)
dBi
-
11.4
13.0

![Image 1 from page 33](/images/cospas-sarsat/T-series/T016/T016_page_33_img_1.png)

5-4

Receive antenna axial ratio
dB
< 2.5
< 1.8
Receive antenna G/T:
At edge of coverage
At centre of coverage
dB/K
> -17.7
> -17.7
> -16.1
System noise temperature(2)
K

Bandpass characteristics
Normal mode
Narrowband mode
> 80 kHz (1.0 dB)
> 90 kHz (3.0 dB)
< 110 kHz (10 dB)
< 170 kHz (45 dB)
< 200 kHz (70 dB)
> 50 kHz (1.0 dB)
< 75 kHz (10 dB)
< 130 kHz (45 dB)
< 160 kHz (70 dB)
> 120 kHz (1 dB)
< 140 kHz (3 dB)
< 170 kHz (10 dB)
< 400 kHz (45 dB)
Not used
> 80 kHz (1 dB)
< 100 kHz (3 dB)
< 125 kHz (10 dB)
< 300 kHz (45 dB)
Not used
> 80 kHz (1 dB)
>90 kHz (3 dB)
< 110 kHz (10 dB)
< 200 kHz (45 dB)
< 270 kHz (70 dB)
N/A
Group delay uncertainty
(95% conf.)
ns
< 500
< 500
Group delay over 4 kHz (slope)
Normal mode
Narrowband mode
μs/4
kHz
< 10
< 10
Transponder gain mode
-
AGC
AGC time constant
ms
< 80
< 80
AGC dynamic range
dB
> 30
> 30
Transponder gain
dB
-
167…185
Transponder linearity (C/I3)
dBc
> 30
> 18
Translation frequency
Hz
-
1,138,849,998.5
1,138,850,000.0
1,138,850,000.0
(Note 3)
Frequency translation:
Accuracy
Short term stability (100 ms)
± 2 x 10-11
< 1 x 10-11
± 2 x 10-11
5 x 10-12
Downlink frequency band
MHz
-
1,544.85 to 1,544.95
Downlink centre frequency
Normal mode
Narrowband mode
MHz
-
1,544.900
1,544.893 - not used
1,544.900
N/A
Downlink antenna polarization
circular
LHCP
Transmit antenna axial ratio
dB
-
< 2
Downlink EIRP
dBW
> 15
> 18
(1)
The receive antenna edge of coverage (EoC) is defined at a beacon elevation angle of 5°.
(2)
Recalculated to the input of the LNA, assuming the external noise temperature of the antenna
Ta = 300 K.
(3)
Translation frequency for CS IDs 507 and 508 is set to 1,138,849,998.5 and is set to 1,138,850,000.0
for CS ID 509 and onward.
5.6.1
Glonass SAR Receiver Parameters
Glonass-K1 series SAR bandpass filters characteristics are provided in
Table 5-2.
Glonass-K2 series SAR bandpass filters are deployed in 44.9 MHz intermediate frequency of SAR
repeater, after frequency downconverter. Bandpass characteristics of the transponder are presented in
Figure 5.4 the normal band.

5-5

Figure 5.4: Glonass-K2 SAR Repeater Normal Bandpass Filtering Performance
5.6.2
Glonass SAR Transmitter Parameters
Glonass-K SAR transmitter parameters are specified in
Table 5-2.
5.6.3
Glonass SAR Antennas
Figure 5.5 and Figure 5.6 show the SAR receive and L-band transmit antenna gain plots for Glonass K
satellites in four characteristic cross-sections.
Figure 5.5: SAR Repeater Receiving Antenna Gain (Four Cross-Sections)

![Image 1 from page 35](/images/cospas-sarsat/T-series/T016/T016_page_35_img_1.png)

![Image 2 from page 35](/images/cospas-sarsat/T-series/T016/T016_page_35_img_2.png)

5-6

Figure 5.6: SAR Repeater Transmitting Antenna Gain (Four Cross-Sections)
- END OF SECTION 5 -

![Image 1 from page 36](/images/cospas-sarsat/T-series/T016/T016_page_36_img_1.png)

6-1

6.
BDS 406 MHZ MEOSAR REPEATER
6.1
BDS MEOSAR Overall Description
The information presented in this section refers to the BD-3 MEO satellites with SARRs onboard.
The BDS MEOSAR satellites are on slots of a Walker 24/3/1 constellation, orbiting at an altitude of
21,528 km and at an inclination angle of 55°. The SAR/BDS payloads are planned to be deployed on
six MEOSAR satellites as defined in Table 6-1.
Table 6-1 shows Keplerian Elements of Nominal Orbital Positions for BD-3 satellites with SAR
payloads, as the epoch time is 00:00:00 on 1 October 2018 (UTC).
Table 6-1: Keplerian Elements of Nominal Orbital Positions
for BDS MEO Satellites with SAR payload
Sat. No.
Slot
Launch date
Semi-
Major
Axis(km)
Orbit
Altitude
(km)
Eccen-
tricity
Inclin-
ation
(deg)
RAAN
(deg)
Arg.
Perigee
(deg)
Arg. f
Latitude
(deg)
Orbital
Period
(min)
BD-3 M13 (632)
B1
19 Sep. 2018
27906.1
21528.0


156.9
0.0
207.9

BD-3 M14 (633)
B3
19 Sep. 2018
27906.1
21528.0


156.9
0.0
297.9

BD-3 M23 (645)
C3
22 Sep. 2019
27906.1
21528.0


276.9
0.0
312.9

BD-3 M24 (646)
C5
22 Sep. 2019
27906.1
21528.0


276.9
0.0
42.9

BD-3 M21 (643)
A6
23 Nov. 2019
27906.1
21528.0


24.2
0.0
105.5

BD-3 M22 (644)
A8
23 Nov. 2019
27906.1
21528.0


24.2
0.0
195.5

6.2
BDS MEOSAR Functional Description
BDS MEOSAR repeaters are based on bent pipe type transponders with no frequency inversion, which
receive signals in the 406.0 to 406.1 MHz band and retransmit at 1.54421 GHz. They are designed in
accordance with MEOSAR space segment interoperability requirements, ensuring their compatibility
and interoperability. Also, BDS will provide return link service (RLS).
Figure 6.1 shows SAR/BDS structure.

6-2

Figure 6.1: Structure of SAR Functions on the BDS Satellites
6.3
BDS Repeater Operating Modes
BDS MEOSARR can operate in single gain and two bandwidth modes.
Repeater gain is self-regulated by Automatic Level Control (ALC). The repeater gain is automatically
adjusted to obtain a power of 16 dBW at the output of the SARR with antenna, neglect the input is
signal or noise.
Repeater normal bandwidth mode is 90 kHz, which is designed to relay second generation beacon
signal. However, narrow band mode (50 kHz) is reserved for special purpose. The bandwidth mode
can be switched via TT&C.
6.4
BDS Repeater Spectrum Characteristics
Figure 6.2: BDS MEOSARR Normal Band Spectrum Characteristics

![Image 1 from page 38](/images/cospas-sarsat/T-series/T016/T016_page_38_img_1.png)

![Image 2 from page 38](/images/cospas-sarsat/T-series/T016/T016_page_38_img_2.png)

6-3

Figure 6.3: BDS MEOSARR Narrow Band Spectrum Characteristics
6.5
BDS Repeater Coverage Area
The BDS SAR repeater is designed to cover the Earth’s disc both in the uplink and the downlink. From
the orbital altitude of a single BDS satellite with SAR repeater, the visible Earth disc covers
approximately 38.6% of Earth’s surface. The difference in the path loss between satellites seen on the
horizon and those appearing in zenith is 2.0 dB.
6.6
BDS MEOSAR Repeater Performance Parameters
Table 6-2 presents the typical measured satellite payload performances based on in-orbit and on-
ground equipment testing.
Table 6-2: Typical SAR/BDS Repeater Design Characteristics
Parameter
Interoperability
Requirement
Design Result of
BDS MEOSARR
Unit
Uplink frequency range
406.0 to 406.1
406.0 to 406.1
MHz
Receive centre
frequency
Normal mode
406.050
406.050
MHz
Narrow band mode
406.043
406.043
Nominal input power at antenna


dBW
Maximum input power at antenna


dBW
System dynamic range


dB
Receive antenna polarisation
RHCP
RHCP
Receive antenna gain at EoC(a)
/
> 11.5
dBi

![Image 1 from page 39](/images/cospas-sarsat/T-series/T016/T016_page_39_img_1.png)

6-4

Parameter
Interoperability
Requirement
Design Result of
BDS MEOSARR
Unit
Receive antenna axial ratio
< 2.5
< 2
dB
Satellite G/T
> -17.7
> -15.3
dB/K
System noise temperature(b)
/
< 480
K
Bandpass
characteristics
Normal mode
1 dB >80 kHz
1 dB >80 kHz
3 dB >90 kHz
3 dB >90 kHz
10 dB <110 kHz
10 dB <110 kHz
45 dB <170 kHz
45 dB <170 kHz
70 dB <200kHz
70 dB <200 kHz
Narrow band mode
1 dB >50 kHz
1 dB >50 kHz
10 dB <75 kHz
10 dB <75 kHz
45 dB <130 kHz
45 dB <130 kHz
70 dB <160 kHz
70 dB <160 kHz
Group delay uncertainty (95% conf.)

< 500
ns
Group delay over
4 kHz (slope)(c)
Normal mode
≤ 10
≤ 9
μs/4kHz
Narrow band mode
≤ 9
Transponder gain modes
/
ALC
ALC time constant
< 80
< 60
ms
ALC dynamic range
> 30
> 32
Transponder gain
> 180
> 180
dB
Transponder linearity
> 30
> 30.5
dBc
Frequency translation accuracy
±2e-11
±2e-11
Frequency translation
Short term stability (100 ms)
≤ 1e-11
≤ 1e-11
Translation frequency stability
/
< 3e-12/1s
< 1e-12/10s
< 3e-13/100s
Downlink frequency band
/
1544.16~1544.26
MHz
Downlink centre
frequency
Normal mode
/
1544.210
MHz
Narrow band mode
/
1544.203
MHz
Downlink antenna polarisation
/
RHCP
Transmit antenna axial ratio
/
< 1.5
dB
Downlink EIRP
> 15
> 18.0
dBW
EIRP stability in ALC mode
/
< 1.0
dBPK-PK
a) The receive antenna edge of coverage (EoC) is defined at a beacon elevation angle of 5°.
b) System noise temperature computed at transponder input.
c) In the 1 dB band.

6-5

6.7
BDS SAR Repeater Receiver Parameters
6.7.1
BDS SAR Repeater Bandpass Parameters
Bandpass filters are deployed in 63.5 MHz intermediate frequency of SAR/BDS repeater, after
frequency down converter. Bandpass characteristics of the filter are presented in Figure 6.4 for both
the normal (90 kHz) and the narrow (50 kHz) bands. These are typical values, considering that there
are small variations with temperature and from unit to unit.
Figure 6.4: BDS MEOSARR Normal and Narrow Bandpass Filtering Performance
6.7.2
BDS MEOSAR Repeater Receive Antenna Pattern
Receive antenna gain is shown in Figure 6.5.
Figure 6.5: SAR/BDS Rx Antenna Gain (Four Cross-Sections)

![Image 1 from page 41](/images/cospas-sarsat/T-series/T016/T016_page_41_img_1.png)

![Image 2 from page 41](/images/cospas-sarsat/T-series/T016/T016_page_41_img_2.png)

6-6

6.7.3
BDS MEOSAR Repeater Transmit Antenna Pattern
Transmit antenna gain is shown in Figure 6.6.
Figure 6.6: SAR/BDS Tx Antenna Gain (Four Cross-Sections)
- END OF SECTION 6 -

![Image 1 from page 42](/images/cospas-sarsat/T-series/T016/T016_page_42_img_1.png)

A-1

ANNEX A: INFORMATION FOR MEOLUT OPERATORS
The complete list of all operational satellites in each constellation with current status as of publication
date is provided in Error! Reference source not found.. A dynamic list is maintained on the Cospas-S
arsat website.
Additional sources regarding the current status of MEOSAR satellites are available on the following
websites:
•
for Galileo satellites:
o http://www.gsc-europa.eu/system-status/Constellation-Information
•
for Glonass satellites:
o http://glonass-iac.ru/en/GLONASS/
•
for GPS satellites:
o http://www.navcen.uscg.gov/?Do=constellationStatus
o http://en.wikipedia.org/wiki/List\_of\_GPS\_satellites
•
for BDS satellites:
o http://www.csno-tarc.cn/en/system/constellation
Information regarding the orbital parameters of MEOSAR satellites is available from:
•
the navigation signals broadcasted from MEOSAR satellites, or
•
http://www.celestrak.com/NORAD/elements/sarsat.txt (data are retrieved from JSpOC via
www.space-track.org) The orbit data are providing using the two-line format, which is defined
at:
o http://spaceflight.nasa.gov/realdata/sightings/SSapplications/Post/JavaSSOP/SSOP\_
Help/tle\_def.html
o http://celestrak.com/NORAD/documentation/tle-fmt.asp
•
the laser-ranging community in CPF format (a derivative of SP3) for Galileo and Glonass
satellites, at:
o ftp://cddis.gsfc.nasa.gov/pub/slr/cpf\_predicts/
o ftp://edc.dgfi.badw.de/pub/slr/cpf\_predicts/
- END OF ANNEX A -

B-1

ANNEX B: MEOSAR SATELLITE TECHNICAL PARAMETERS
B.1
MEOSAR Satellite Identification Parameters
Table B-1: MEOSAR Satellite Identification Parameters
The up-to-date version of this table is available on the Cospas-Sarsat website www.cospas-sarsat.int.
Cospas-Sarsat
Satellite ID
code
(note 1)
NORAD ID (NASA
Catalogue Number)
(note 2)
International
Designator
(note 3)
Satellite Name
(note 4)
Space Vehicle
Number (SVN)
(note 5)
Other Names
Other Names
Other Names
PRN
Number
(note 6)
Launch Date
DASS
S-Band
Galileo
Glonass
BDS
Notes:
1 Cospas-Sarsat Satellite ID Code number is a unique 3-digit number allocated by Cospas-Sarsat for each operating, SAR-equipped satellite (as
defined in document C/S R.012, page M-2), based on PRN or SVN, so PRNs would get re-assigned to future replacement satellites.
2 A unique 5-digit ID number for each satellite, permanently assigned to that object in orbit.
3 5-digit designator comprising the last 2 digits of the launch year and 3 digits of the launch number in that year plus one letter for each piece
of the launch (A, B, C...).
4 Satellites have various names and designations by different users in different databases, as shown in the ¨Other Names¨ columns. DASS refers
to an experimental S-band payload on some GPS Block 2 satellites.
5 SVN is a unique satellite or space vehicle number assigned by the satellite constellation owner or operator.
6 PRN is a pseudo-random noise code number assigned by the satellite owner or operator to identify the code for GNSS receivers to decode the
navigation signal. As there is a limited supply of PRN numbers, they get gets reassigned to new satellites that replace older, decommissioned
satellites. Final PRN numbers are not yet assigned to the initial Galileo and Glonass satellites.
7 Galileo 411 and 412 should not be tracked by MEOLUTs as they are not equipped with a SAR repeater. However, Galileo 411 and 412 will
be used for the return link service provided by Galileo.

B-2

B.2
RF Configuration of the MEOSAR satellites
Table B-2: Current RF Configuration of the MEOSAR Satellites
The up-to-date version of this table is available on the Cospas-Sarsat website www.cospas-sarsat.int.
Cospas-Sarsat
Satellite ID
code
(note 1)
Downlink
Frequency Band
(note 2)
Nominal
Downlink Centre
Freq (MHz)
(notes 3 & 4)
Repeater
Frequency
Translation
(note 5)
Uplink Antenna
Polarization
(note 6)
Downlink
Antenna
Polarization
(note 6)
Current BW
(kHz) @Centre
Frequency (MHz)
(note 7)
Current
mode
(note 8)
Comments
DASS
S-Band
Galileo
Glonass
BDS
Notes:

Cospas-Sarsat Satellite ID Code number is a unique 3-digit number allocated by Cospas-Sarsat for each operating, SAR-equipped satellite (as
defined in document C/S R.012, page M-2), based on PRN or SVN, so PRNs would get re-assigned to future replacement satellites.

The S-band downlink is in a band normally used for telemetry, whereas the L-band is in the 1 MHz bandwidth allocated by ITU for Distress
and Safety, space-to-Earth, so has protection from harmful interference.

The nominal downlink centre frequency corresponds to the 406.050 MHz received frequency, which is the centre of the 100 kHz SAR band
allocated for distress beacons. The exact centre frequency can be derived from information provided in the tables providing the SAR Receiver
Parameters in section 4.6, Table 4.3.

The repeater bandwidth of the S-band satellites is about 270 kHz; Galileo is about 80 kHz, or else 50 kHz in narrowband mode (with centre
frequency shifted 7 kHz lower) and Glonass is about 100 kHz, or else 60 kHz in narrowband mode (with centre frequency shifted 7 kHz lower).

The S-band payloads on the Block 2 GPS satellites have “inverted” frequency translation of the relayed 406 MHz frequencies, whereas the L-
band satellites, including the future  SAR/GPS, are designed for SAR purposes, and do not invert the relayed band.

Future SAR/GPS L-band satellites will have an RHCP downlink, and transmit on the same downlink frequency as Glonass, but with opposite
polarization.

Downlink frequency is that frequency referenced to 406.05 MHz. Downlink frequency may not be exact. It is to be noted that any satellite may
have a nominal offset of [± 100 Hz]. However, once this value is set for each repeater, the frequency translation accuracy requirement applies.
The format is [1544.xxxxxxx MHz] (8 decimal places) (TBC).

Current mode:
•
WA = Wideband filter and ALC

B-3

•
NA = Narrowband filter and ALC
•
WF = Wideband filter and fixed gain
•
NF = Narrowband filter and fixed gain
•
UT = under test
•
OFF

B-4

Table B-3: DASS S-Band Filter Settings
The up-to-date version of this table is available on the Cospas-Sarsat website www.cospas-sarsat.int.


6a
6b
6c
6d
6e


10a
10b
10c
10d

SAT\_I
D
MODE
\_ID
BW
(kHz)
Centre
Frequency
(MHz)
Group Delay
@ Centre
Frequency
Coeff. a0 (µs)
Group Delay Data Curve Fit Coeff.
Group Delay
Uncertainty (ns)
FG
Setting
(dB)
Short
Term
Stability
Pre-Filter Characteristics
Historical
a1
a2
a3
a4
a5
3 dB
BW
(kHz)
10 dB
BW
(kHz)
45 dB
BW
(kHz)
BWn
(kHz)
Table B-4: Galileo Filter Settings
The up-to-date version of this table is available on the Cospas-Sarsat website www.cospas-sarsat.int.


6a
6b
6c
6d
6e


10a
10b
10c
10d

SAT
\_ID
MODE
\_ID
BW
(kHz
)
Centre
Frequenc
y (MHz)
Group Delay
@ Centre
Frequency
Coeff. a0 (µs)
Group Delay Data Curve Fit Coeff.
Group
Delay
Uncertainty
(ns)
FG
Setting
(dB)
Short Term
Stability
Pre-Filter Characteristics
Histori
cal
a1
a2
a3
a4
a5
3 dB
BW
(kHz)
10 dB
BW
(kHz)
45 dB
BW
(kHz)
BWn
(kHz)
Table B-5: GPS L-Band Filter Settings (To Be Completed)
The up-to-date version of this table is available on the Cospas-Sarsat website www.cospas-sarsat.int.


6a
6b
6c
6d
6e


10a
10b
10c
10d

SAT\_ID
MODE\_ID
BW
(kHz)
Centre
Frequency
(MHz)
Group Delay
@ Centre
Frequency
Coeff. a0 (µs)
Group Delay Data Curve Fit Coeff.
Group
Delay
Uncertainty
(ns)
FG
Setting
(dB)
Short Term
Stability
Pre-Filter Characteristics
Historical
a1
a2
a3
a4
a5
3 dB
BW
(kHz)
10 dB
BW
(kHz)
45 dB
BW
(kHz)
BWn
(kHz)
Table B-6: Glonass L-Band Filter Settings
The up-to-date version of this table is available on the Cospas-Sarsat website www.cospas-sarsat.int.


6a
6b
6c
6d
6e


10a
10b
10c
10d

SAT\_ID
MODE\_ID
Group Delay Data Curve Fit Coeff
Pre-Filter Characteristics
Historical

B-5

BW
(kHz)
Centre
Frequency
(MHz)
Group Delay
@ Centre
Frequency
Coeff. a0 (µs)
a1
a2
a3
a4
a5
Group
Delay
Uncertainty
(ns)
FG
Setting
(dB)
Short Term
Stability
3 dB
BW
(kHz)
10 dB
BW
(kHz)
45 dB
BW
(kHz)
BWn
(kHz)
Table B-7: BDS L-Band Filter Settings
The up-to-date version of this table is available on the Cospas-Sarsat website www.cospas-sarsat.int.


6a
6b
6c
6d
6e


10a
10b
10c
10d

SAT\_ID
MODE\_ID
BW
(kHz)
Centre
Frequency
(MHz)
Group Delay
@ Centre
Frequency
Coeff. a0 (µs)
Group Delay Data Curve Fit Coeff.
Group
Delay
Uncertainty
(ns)
FG
Setting
(dB)
Short Term
Stability
Pre-Filter Characteristics
Historical
a1
a2
a3
a4
a5
3 dB
BW
(kHz)
10 dB
BW
(kHz)
45 dB
BW
(kHz)
BWn
(kHz)
As group delay data curve fit coefficients is calculated by using script polyfit (Frequency, Group\_Delay, 5) in Octave or Matlab, as unit of Frequency is
Herz, of Group\_Delay is second, and a1 to a5 are first to fifth coefficients of the 6-term polynomial.
Additional information on the columns:
1 SAT\_ID is the unique identifier format that is the same as defined for MEOSAR satellite identification. There are a maximum of four modes per
satellite but only one will be in selected at any time. Therefore, any satellite ID will have data populated in rows equal to the number of satellite
modes as defined by column 3.
2 MODE\_ID is a single unique identifier defining the specific single satellite mode. All data contained in the row are the space segment parameter
values for the unique combination of SAT\_ID and MODE\_ID. The four unique identifiers are:
•
WA = Wideband filter and ALC,
•
NA = Narrowband filter and ALC,
•
WF = Wideband filter and Fixed Gain,
•
NF = Narrowband filter and Fixed Gain.
3 BW is the bandwidth associated with the MODE\_ID.
4 Centre frequency associated with the MODE\_ID.

B-6

5 Group delay is a single value that defines the actual group delay at 406.05 MHz for wideband filter and 406.43 MHz for narrowband. The format
is xx.y in microseconds. This value is coefficient a0 derived from the group curve fit data defined in column 5 at the associated downlink frequency
(see Table B-4) for wideband and narrowband filters.
6 The group delay curve fit data defines the coefficients of the group delay variation curve as a function of frequency over the respective filter’s 1
dB bandwidth. This data represents a single best fit curve of the filter’s group delay performance as a function of a variety of environmental
conditions. Coefficient a0 is the group delay at the associated downlink frequency (see Table B-4) for wideband and narrowband filters. Note this
value is populated in column 4.
7 Group delay uncertainty is single value defining the maximum error of the actual group delay due to any satellite environmental condition from
the best fit curve (columns 5 and 6) and quantifies the uncertainty of the delay through the satellite at any time. The format is a single integer
number in nanoseconds.
8 The FG gain setting is a single value that sets the gain of the transponder/repeater for the nominal output power. This value only applies to
MODE\_ID WF and NF. Format is xx.
9 Short term frequency stability is a value quantifying the actual performance of the satellite for any 100 ms per document C/S R.012 (< 1 x 10-11).
The method to assess the short term frequency stability is still to be confirmed.
10 Pre-Filter Characteristics provides the BW range in kHz (yyy) for 3 dB, 10 dB, 45 dB rejection points, and noise bandwidth. MEOSAR payload
providers should provide within future technical documents rejection characteristics of any repeater filtering. The bandwidth at rejection points of
3 dB, 10 dB, and 45 dB should be provided at a minimum within this Annex. Final rejection values (i.e., 60 dB or 70 dB) and its respective BW
should be provided in future technical documents. In addition, to quantify the impacts of the general background interfering noise signals, the
knowledge of the equivalent Gaussian noise bandwidth, BWn in kHz (xxxxx) of any repeater input filtering if used would be beneficial for
definition of ITU protection requirement and should be provided in future technical documents . This is fourth sub-column (10d).
11 Column 11 is intended to provide a means whereby historical data can be accessed. For the current mode selected, the start date and UTC time of
when this current mode was in use is provided at the top of its cell (i.e., since 1 September 2011). The date should be specified in the format
dd/mm/yyyy, where dd is the day of the month, mm is the month (as a number), and yyyy is the year. The time should be specified as hh:mm:ss,
where hh is hour, mm is minutes, and ss is seconds.
- END OF ANNEX B -

C-1

ANNEX C: MEOSAR ORBITAL DATA DESCRIPTION
C.1
Introduction
Precise satellite position vectors and velocity vectors are essential for location processing as they
directly impact the achievable accuracy of beacon locations (satellite position and velocity vector
errors are part of the location error budget). These vectors can be computed from the ephemeris
broadcasted in the navigation message by GNSS satellites.  However the ephemeris data may not be
available for the following reasons:
•
if the navigation signal is not available (e.g., no navigation signal broadcasted by the satellite,
navigation signal not processed by the GNSS receiver, etc.), or
•
if the station GNSS receiver has failed.
A MEOLUT may acquire satellite position vectors and velocity vectors by other means, such as from
an on-line source.
C.2
Summary of available MEOSAR Satellite Orbital Data and Associated Accuracy
Performance
The following table represents values of the parameters that the service providers are intending to
provide (url to be specified later for ground server).
Table C-1: Parameters that Service Providers Are Intending to Provide
MEOSAR
Constellation
Orbital Data Type
Duration of
Data Validity
(days)
Update
Rate
(hours)
Latency
(hours)
Position
Accuracy
(meters)
Data Source
Galileo
Sp3

12v
< 2

Ground server
Rinex 3.0
7 6

< 2

Ground server
Ephemerids
0.167 (4 hours)

< 2

Ground server
Almanac
TBD

< 2
TBD
Ground server
Broadcasted ephemerids
100 min
TBC
0 (real time)
< 1
Satellite
Broadcasted almanac
TBC
TBC
TBC
TBC
Satellite
GPS DASS
Sp3


< 2
< 1
Ground server
Rinex 2.1
0.083 (2 hours)

< 1
< 1
Ground server
Broadcasted ephemerids
0.167 (4 hours)

0 (real time)
< 1
Satellite
Broadcasted almanac


0 (real time)
< 1,000
Satellite
6 Each file contains several blocks of data. The whole file covers 7 days prediction, each block is valid for 4 hours.

C-2

MEOSAR
Constellation
Orbital Data Type
Duration of
Data Validity
(days)
Update
Rate
(hours)
Latency
(hours)
Position
Accuracy
(meters)
Data Source
GPS L-Band
Sp3


< 2
< 1
Ground server
Rinex 2.1
0.083 (2 hours)

< 1
< 1
Ground server
Broadcasted ephemerids
0.167 (4 hours)

0 (real time)
< 1
Satellite
Broadcasted almanac


0 (real time)
< 1,000
Satellite
Glonass
Rinex
0.021 (30 min)

< 1
< 1 over 30 min
< 15 over 1 hour
Ground server
Sp3 – ultra rapid


< 4
< 2
Ground server
SP3 - rapid


< 15
< 4
Ground server
Broadcasted ephemerids
0.021 (30 min)
0.5
0 (real time)
< 1
Satellite
Broadcasted almanac


0 (real time)
< 1,000
Satellite
BDS
Sp3 (final)


< 1
Ground server
Ephemerids
0.083
(2 hours)


< 2.5
Ground server
Almanac
< 7


< 1,000
Ground server
Broadcasted ephemerids
0.083
(2 hours)


< 2.5
Satellite
Broadcasted almanac
< 7


< 1,000
Satellite
Note: characteristics regarding broadcasted almanacs are provided for information only.
Galileo notes:
GSC (Galileo Service Center) data are linked to GST (Galileo System Time). In order to use
Galileo orbital data the following information are needed:
•
the clock corrections,
•
the GST-UTC differences.
Furthermore GST-GPS time differences may also be helpful. This information is contained in
Rinex 3.0 only (SP3 do not contain it).
GPS DASS notes: to be supplied
GPS L-band notes: to be supplied
BDS notes:
sp3 is gizp compressed, and can be obtained from

C-3

•
http://en.igmas.org/Product/TreePage/tree/nav\_id/36/cate\_id/37.html ; and
•
ftp://cospas:cospas-sarsat@ftp.csno-tarc.cn/eph.
Ephemerids can be obtained from: ftp://cospas:cospas-sarsat@ftp.csno-tarc.cn/brdc.
Almanac can be obtained from: ftp://cospas:cospas-sarsat@ftp.csno-tarc.cn/almanac.
Glonass notes: applies to commissioned Glonass-M series only, will include Glonass-K when
commissioned into the Glonass system.
C.3
Definitions
Orbit data product
Set of satellite orbit data information allowing to determine future satellite locations and/or velocity
vectors. Orbit data products can be provided in different formats (SP3, Rinex, ephemerids, almanac,
xml, etc.)
Standard Product 3 (SP3) format
The Standard Product \#3 (SP3) format is used to exchange orbital information in the form of tabular
ephemerides of satellite positions every 15 min expressed. Associated consistent estimates for the
satellite clocks are also provided at 15-min intervals.
Ephemeris Data
Ephemeris data is a set of parameters that can be used to accurately calculate the location of a GNSS
satellite at a particular point in time. It describes the path that the satellite is following as it orbits Earth.
Ephemeris data are valid for a certain period of time, typically 4 hours for GPS and Galileo.
Almanac Data
The GPS almanac is a set of data that every GNSS satellite transmits, and it includes information about
the state (health) of the entire GPS satellite constellation, and coarse data on every satellite's orbit.
When a GNSS receiver has current almanac data in memory, it can acquire satellite signals and
determine initial position more quickly.
RINEX
Receiver Independent Exchange Format (RINEX) is a data interchange format for raw satellite
navigation system data. This allows the user to post-process the received data to produce a more
accurate result. RINEX is the standard format that allows the management and disposal of the measures
generated by a receiver, as well as their off-line processing by a multitude of applications.  The RINEX
format is designed to evolve over time, adapting to new types of measurements and new satellite
navigation systems.
There is basically two types of RINEX data:
•
Observation Data which contains receiver measurements (pseudoranges, Doppler, C/N0,
etc…)
•
Navigation Data which contain the ephemeris parameters as read by the receiver from the
navigation message
Definitions related to the timeline for making orbit data products available through ground servers:
•
tobs: observation time, i.e., time at which satellite orbits are ultimately observed to produce the
orbit data products

C-4

•
tFTP: time at which the orbit data product are made available to users on the FTP server
•
latency: duration required to produce the orbit data products (i.e., time elapsed between tobs
and the time when the data are made available to users on the FTP server). Latency may vary
based on conditions.
•
validity: duration during which the orbit data product are valid (i.e., duration for which the
orbit data products are within accuracy values guaranteed by the space segment provider)
•
update rate (expressed in hours): duration between two successive orbital data products be
made available on the FTP server (i.e., refresh rate of the files on the FTP server).
Latency and validity timeline
An illustration of the definitions above is provided in the schematic below (latency and update rate
may vary based on conditions).
Figure C.1: Latency and Validity Timeline
- END OF ANNEX C -
- END OF DOCUMENT -
Latency
tobs\_1
Validity
tobs\_2
Validity
Update rate
Latency
tFTP\_1
tFTP\_2
Time

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Cospas-Sarsat Secretariat
1250 Boul. René-Lévesque West, Suite 4215, Montreal (Quebec) H3B 4W8  Canada
Telephone: +1 514 500 7999  /  Fax: +1 514 500 7996
Email: mail@406.org
Website: www.406.org