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T003: C/S T.003 - Issue 5 Rev. 1

Official Cospas-Sarsat T-series document T003

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March 2022

C/S T.003 - Issue 5 Rev. 1

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Series: T-Series (Technical) Version: Issue 5 - Revision 1 Date: March 2022 Source: Cospas-Sarsat Official Documents

DESCRIPTION OF THE 406-MHz PAYLOADS USED IN THE COSPAS-SARSAT LEOSAR SYSTEM C/S T.003 Issue 5 – Revision 1

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

Approved (CSC-1)

Approved (CSC-7)

Approved (CSC-9)

Approved (CSC-15)

Approved (CSC-25)

Approved (CSC-27)

Approved (CSC-31)

Approved (CSC-37)

Approved (CSC-39)

Approved (CSC-41)

Approved (CSC-45)

Approved (CSC-53)

Approved (CSC-57)

Approved (CSC-59)

Approved (CSC-66)

TABLE OF CONTENTS Page History ................................................................................................................................................. i Table of Contents ................................................................................................................................. ii List of Figures ................................................................................................................................. v List of Tables ................................................................................................................................. v 1. INTRODUCTION .............................................................................................. 1-1 Purpose 1-1 Scope 1-1 Reference Documents .......................................................................................... 1-1 2. COSPAS-SARSAT PARAMETERS ................................................................ 2-1 Cospas-Sarsat Payloads ........................................................................................ 2-1 2.1.1 Cospas-Sarsat Payload Summary ............................................................. 2-1 2.1.2 Cospas Payload System Functional Diagram .......................................... 2-1 Sarsat Payload ...................................................................................................... 2-2 2.2.1 Sarsat Payload Summary .......................................................................... 2-3 2.2.2 Sarsat Payload System Functional Diagram ............................................ 2-3 Interoperability Parameters .................................................................................. 2-6 2.3.1 Orbit Parameters ....................................................................................... 2-6 2.3.2 Input Parameters ....................................................................................... 2-7 2.3.3 Output Parameters .................................................................................... 2-8 2.3.4 Biphase-L Data Encoding ........................................................................ 2-9 3. COSPAS-SARSAT REPEATERS .................................................................... 3-1 Cospas Repater ..................................................................................................... 3-1 Sarsat Repeater SARR-1 (Sarsat-13 and earlier) ................................................. 3-3 3.2.1 Sarsat SARR-1 Receivers......................................................................... 3-4 3.2.2 Sarsat SARR-1 1544.5 MHz Transmitter ................................................ 3-7 Sarsat Repeater SARR-2 (Sarsat-14 and after) .................................................. 3-11 3.3.1 SARR-2 Power, Telemetry and Command ............................................ 3-12 3.3.2 SARR-2 Frequency Generator ............................................................... 3-12 3.3.3 SARR-2 SAW FILTER .......................................................................... 3-12 3.3.4 Sarsat SARR-2 1544.5 MHz Transmitter .............................................. 3-13 4. COSPAS-SARSAT SARPS ................................................................................ 4-1 Cospas SARP ....................................................................................................... 4-1

4.1.1 Cospas SARP-2 Receiver Processor ........................................................ 4-1 4.1.2 Cospas SARP-2 Frame Formatter ............................................................ 4-3 4.1.3 Cospas SARP-2 Output Format ............................................................... 4-4 Sarsat SARP ......................................................................................................... 4-7 4.2.1 Sarsat SARP-2 .......................................................................................... 4-7 4.2.2 Sarsat SARP-3 ........................................................................................ 4-14 5. COSPAS-SARSAT ANTENNAS ...................................................................... 5-1 Cospas Antennas .................................................................................................. 5-1 5.1.1 Cospas Receive Antennas ........................................................................ 5-1 5.1.2 Cospas Transmit Antenna ........................................................................ 5-1 Sarsat-TIROS Antennas ....................................................................................... 5-3 5.2.1 Sarsat-TIROS Receive Antennas ............................................................. 5-3 5.2.2 Sarsat-TIROS Transmit Antenna ............................................................. 5-3 Sarsat-METOP Antennas ..................................................................................... 5-7 5.3.1 Sarsat-METOP Receive Antennas ........................................................... 5-7 5.3.2 Sarsat-METOP Transmit Antenna ........................................................... 5-8 Sarsat-NPOESS Antennas .................................................................................... 5-9 5.4.5 Sarsat-NPOESS Receive Antenna ......................................................... 5-10 5.4.6 Sarsat-NPOESS Transmit Antenna ........................................................ 5-10 ANNEX A : LIST OF ABBREVIATIONS AND ACRONYMS ........................................ A-1 ANNEX B : COSPAS-SARSAT LEOSAR FREQUENCIES ............................................. B-1 B.1 Introduction ......................................................................................................... B-1 B.2 Frequency Matters ............................................................................................... B-1 B.2.1 Frequency Requirements ......................................................................... B-1 B.2.2 Interference.............................................................................................. B-2

LIST OF FIGURES Figure 1-1 Illustration of Cospas and Sarsat LEOSAR Satellites .................................... 1-2 Figure 2-1: Cospas-Sarsat System Functional Diagram ......................................................... 2-2 Figure 2-2: Sarsat-TIROS Payload and Spacecraft Interface Functional Diagram with SARR-1 and SARP-2 or SARP-3 ....................................................................................... 2-4 Figure 2-3: Sarsat-METOP Payload and Spacecraft Interface Functional Diagram with SARR- 1 and SARP-3 ....................................................................................................... 2-5 Figure 2-4: Sarsat Payload and Spacecraft Interface Functional Diagram with SARR-2 and SARP-3 ................................................................................................................. 2-6 Figure 2-5: Processed Data Encoding Scheme ....................................................................... 2-9 Figure 3-1: Cospas Repeater Functional Diagram .................................................................. 3-1 Figure 3-2: Cospas 1544.5 MHz Transmitter Functional Diagram ........................................ 3-2 Figure 3-3: Typical Cospas 1544.5 MHz Observed Downlink Signal ................................... 3-3 Figure 3-4: Sarsat SARR-1 Functional Diagram .................................................................... 3-4 Figure 3-5: Sarsat SARR Receiver Functional Diagram ........................................................ 3-6 Figure 3-6: Sarsat SARR Receiver Bandpass Characteristics ................................................ 3-7 Figure 3-7: Sarsat SARR-1 1544.5 MHz Transmitter Functional Diagram ........................... 3-8 Figure 3-8: Sarsat SARR-1 Baseband Frequency Spectrum ................................................... 3-9 Figure 3-9: Typical Sarsat SARR-1 1544.5 MHz Observed Downlink Signal .................... 3-10 Figure 3-10: Sarsat SARR Transmitter Spurious Emission Limits ........................................ 3-11 Figure 3-11: Sarsat SARR-2 Functional Diagram .................................................................. 3-12 Figure 3-12: Sarsat SARR-2 1544.5 MHz Transmitter Functional Diagram ......................... 3-14 Figure 3-13: Sarsat SARR-2 Baseband Frequency Spectrum ................................................. 3-14 Figure 3-14: Typical Sarsat SARR-2 1544.5 MHz Observed Downlink Signal .................... 3-15 Figure 4-1: Cospas SARP-2 Receiver Processor Functional Diagram ................................... 4-2 Figure 4-2: Cospas SARP-2 Frame Formatter Functional Diagram ....................................... 4-4 Figure 4-3: Example of a Cospas SARP-2 Output Message ................................................... 4-6 Figure 4-4: Cospas SARP-2 Short Message Bit Format ......................................................... 4-6 Figure 4-5: Cospas SARP-2 Long Message Bit Format ......................................................... 4-7 Figure 4-6: Sarsat SARP-2 Functional Diagram ..................................................................... 4-9 Figure 4-7: Example of a Sarsat SARP-2 Output Message .................................................. 4-12 Figure 4-8: Sarsat SARP-2 Short Message Bit Format ......................................................... 4-12 Figure 4-9: Sarsat SARP-2 Long Message Bit Format ......................................................... 4-13 Figure 4-10: Sarsat SARP-3 Functional Diagram ................................................................... 4-15 Figure 4-11: Example of a Sarsat SARP-3 Output Message .................................................. 4-18 Figure 4-12: Sarsat SARP-3 Short Message Bit Format ......................................................... 4-19 Figure 4-13: Sarsat SARP-3 Long Message Bit Format ......................................................... 4-19 Figure 4-14: Sarsat SARP-3 House-Keeping (HK) Message Bit Format ............................... 4-20 Figure 5-1: Cospas Antenna System Functional Diagram ...................................................... 5-2 Figure 5-2: Cospas (SARP-2) 406 MHz Receive Antenna (SPA) Gain Pattern ..................... 5-2 Figure 5-3: Cospas (SARP-2) 1544.5 MHz Transmit Antenna (SLA) Gain Pattern .............. 5-3 Figure 5-4: Sarsat-TIROS Antenna System Functional Diagram ........................................... 5-4 Figure 5-5: Sarsat-TIROS 406.05 MHz Receive Antenna (SRA) Gain Pattern ..................... 5-5 Figure 5-6: Sarsat-TIROS SARP Receive Antenna (UDA) Gain Pattern (at receiver input) . 5-6 Figure 5-7: Sarsat-TIROS 1544.5 MHz Transmit Antenna (SLA) Gain Pattern .................... 5-7

Figure 5-8: Sarsat-METOP Antenna System Functional Diagram ......................................... 5-8 Figure 5-9: Sarsat-METOP 406 MHz SARR and SARP Receive Antenna (CRA) ............... 5-9 Figure 5-10: Sarsat-METOP 1544.5 MHz Transmit Antenna (SLA) Gain Pattern .................. 5-9 Figure 5-11: Sarsat-NPOESS Antenna System Functional Diagram ..................................... 5-10 Figure 5-12: Sarsat-NPOESS Receive Antenna Gain Pattern ................................................ 5-11 Figure 5-13: Sarsat-NPOESS Transmit Antenna Gain Pattern ............................................... 5-11 LIST OF TABLES Table 2.1: Cospas and Sarsat Satellites Orbital Parameters .................................................. 2-7 Table 2.2: Functions Provided by Cospas and Sarsat Satellites ............................................ 2-7 Table 2.3: Cospas and Sarsat Input Parameters ..................................................................... 2-8 Table 2.4: Cospas and Sarsat Output Parameters ................................................................ 2-10 Table 3.1: Cospas 1544.5 MHz Transmitter Parameters ....................................................... 3-2 Table 3.2: Sarsat SARR Receiver Parameters ....................................................................... 3-5 Table 3.3: Sarsat SARR-1 1544.5 MHz Transmitter Parameters .......................................... 3-8 Table 3.4: Sarsat SARR-2 1544.5 MHz Transmitter Parameters ........................................ 3-13 Table 4.1: Cospas SARP-2 Parameters ................................................................................. 4-2 Table 4.2: Sarsat SARP-2 Parameters ................................................................................... 4-8 Table 4.3: Sarsat SARP-3 Parameters ................................................................................. 4-14 Table B-1: Cospas Sarsat LEOSAR Frequencies .................................................................. B-2

1-1

INTRODUCTION The Cospas-Sarsat space segment consists of the Cospas and Sarsat satellites and their respective search and rescue (SAR) payloads. The SAR payload consists of the SAR repeaters (SARR), SAR processors (SARP) and SAR antennas. The Cospas satellites and SAR payloads are provided by Russia. The Sarsat satellites and SAR antennas are provided by USA and Europe. The Sarsat SARR and SARP are provided by Canada and France respectively. Purpose The purpose of this document is to describe the performance parameters of each generation of the Cospas and Sarsat payloads and of the downlink signals for nominal operational satellites. This document is intended to be used to ensure the interoperability of the Cospas and Sarsat satellites and to sufficiently define the downlink to ensure compatible design of LUTs. This document is not intended to be used as a specification for the procurement of hardware for the space segment. Scope This document presents the technical definition and parameters of the Cospas-Sarsat space segment. It is divided into the following sections, where part 1 of each section covers Cospas payloads and part 2 covers Sarsat payloads: section 2 describes the Cospas and Sarsat payloads and the interoperability parameters; section 3 gives the technical parameters of all repeaters; section 4 gives the technical parameters of all processors; and section 5 gives the technical parameters of all antennas. Reference Documents C/S G.003 : Introduction to the Cospas-Sarsat System; C/S S.011 : Cospas-Sarsat Glossary; C/S T.001 : Specification for Cospas-Sarsat 406 MHz Distress Beacons; C/S T.002 : Cospas-Sarsat LEOLUT Performance Specification and Design Guidelines; and C/S T.006 : Cospas-Sarsat Orbitography Network Specification.

1-2

Figure 1-1 Illustration of Cospas and Sarsat LEOSAR Satellites Note: Under nominal operating conditions, the Cospas-Sarsat LEOSAR Space Segment consists of four satellites, two Cospas and two Sarsat, in near-polar orbit.

END OF SECTION 1 -

2-1

COSPAS-SARSAT PARAMETERS The payloads and interoperability parameters for the Cospas-Sarsat space segment are summarised in this section. Cospas-Sarsat Payloads 2.1.1 Cospas-Sarsat Payload Summary The Cospas payload is composed of: a SAR repeater (SARR); a SAR processor (SARP); and uplink and downlink antennas. The SARR provides local mode coverage for the 406 MHz band. The SARP provides both local mode and global mode coverage for the 406 MHz band. Cospas satellites have an improved SARP with memory (SARP-2). Processed data is transmitted to the ground stations via the downlink transmitter. Cospas SARR and SARP are described in sections 3.1 and 4.1 respectively. Processed data is transmitted to the ground stations via the downlink transmitter. Antenna parameters are given in sub-section 5.1. 2.1.2 Cospas Payload System Functional Diagram The Cospas payload system functional diagram is shown in Figure 2.1. The downlink signal from the SAR L-Band transmit Antenna (SLA) can be detected by any Cospas-Sarsat Local User Terminal in the LEOSAR satellite system (LEOLUT).

2-2

Figure 2-1: Cospas-Sarsat System Functional Diagram Sarsat Payload SARSAT payload descriptions in this document cover payloads on-board TIROS, METOP and the future SIDAR satellites. The first generation of SAR Repeaters (SARR-1) is currently in service on TIROS and METOP satellites. The second generation of SAR Repeaters (SARR-2) will be on-board any future Sarsat- LEOSAR satellites and has been designed with the PDS channel exclusively.

2-3

The second generation of SAR Processors (SARP-2) is in service on TIROS satellites (Sarsat-7 to Sarsat-10). The third generation of SAR Processors (SARP-3) is in service on METOP-A (Sarsat- 11), the last TIROS satellite (Sarsat-12), METOP-B (Sarsat-13) and any future Sarsat-LEOSAR satellites. 2.2.1 Sarsat Payload Summary The Sarsat payload is composed of: a SAR repeater (SARR); a SAR processor (SARP); and uplink and downlink antennas. The SARR provides local mode coverage for the 406 MHz band and its parameters are given in sub-section 3.2 for SARR-1 and PDS only coverage as given in sub-section 3.3 for SARR-2. The SARP provides both local mode and global mode coverage for the 406 MHz band. Sarsat satellites may have one of two possible SARP configurations installed: SARP-2 or SARP-3. These processors are described in sub-sections 4.2.1 and 4.2.2 respectively. Processed data is transmitted to the ground stations by the repeater downlink transmitter. Antenna parameters for the payload are given in sections 5.2, 5.3 and 5.4 for the TIROS, METOP and SIDAR satellites respectively. 2.2.2 Sarsat Payload System Functional Diagram As shown on the Sarsat payload functional diagram in Figures 2.2, 2.3 and 2.4, the 2.4 kbps digital data is routed directly to the SARR.

2-4

Figure 2-2: Sarsat-TIROS Payload and Spacecraft Interface Functional Diagram with SARR-1 and SARP-2 or SARP-3

2-5

Figure 2-3: Sarsat-METOP Payload and Spacecraft Interface Functional Diagram with SARR-1 and SARP-3

2-6

Figure 2-4: Sarsat Payload and Spacecraft Interface Functional Diagram with SARR-2 and SARP-3 Interoperability Parameters 2.3.1 Orbit Parameters Basic orbital parameters for Cospas and Sarsat satellites are listed in Table 2.1. Each satellite is in a different orbital plane.

2-7

Table 2.1: Cospas and Sarsat Satellites Orbital Parameters Parameters Unit Cospas on Meteor-M Sarsat on TIROS Sarsat on METOP Orbit Type N/A Circular, Sun- Synchronous, Near-Polar Circular, Sun-Synchronous Circular, Sun-Synchronous Altitude km

(mean value) 833 to 870 800 to 850 Inclination Deg 98.85 98.7 to 98.86 98.7 Period min 101.41 101.35 to 102.12 100 to 101.7 Eccentricity N/A 0.00124 <0.001 0.001165 2.3.2 Input Parameters Table 2.2 lists the functions that are provided by each type of satellite and identifies where they are described within this document. Table 2.2: Functions Provided by Cospas and Sarsat Satellites Functions Cospas Sarsat 406 MHz Repeater Section 3.1 Section 3.2 (SARR-1) Section 3.3 (SARR-2) 406 MHz Processor Section 4.1 Section 4.2 Table 2.3 lists input parameters for individual functions provided by the satellites.

2-8

Table 2.3: Cospas and Sarsat Input Parameters Parameters Unit Cospas Sarsat 406 MHz Repeater: Centre Frequency MHz 406.05 406.05 (See note 4) 1 dB Bandwidth kHz 80.0 80.0 (See note 4) Receiver Noise Temperature K

350 (See note 4) S/C Antenna Polarisation N/A RHCP RHCP (See note 4) Nominal Background Noise K N/A 1000 (See note 4) 406 MHz SARP Processor: Centre Frequency MHz See Note 1 See Notes 2 and 3 1 dB Bandwidth kHz See Note 1 See Notes 2 and 3 Receiver Noise Temperature K

Input Signal from Beacon a. Power Flux Density: (Nominal orbit) Maximum: Nominal: b. Polarisation: dBW/m2 N/A -121.4 -142.4 Linear/RHCP -120.0 -141.0 Linear/RHCP S/C Antenna Polarisation N/A RHCP Nominal Background Noise K

Note 1: SARP-2 allows selection of three different centre frequencies and bandwidths, as listed in Table 4.1. Note 2: SARP-2 allows selection of three different centre frequencies and bandwidths, as listed in Tables 4.2 and 4.3. Note 3: SARP-3 has a fixed bandwidth of 80 kHz centered at 406.050 MHz. Note 4: SARR-1 only. 2.3.3 Output Parameters Table 2.4 provides downlink signal parameters for each type of satellite. The modulation index given in the table for each channel is the Root-Mean-Square (RMS) value of the carrier phase deviation due to that channel. The composite modulation index (RMS) is equal to the square root of the sum of the squares of the individual channel modulation indices. The RMS values are related to other common methods of measurement as follows.

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For the Processed Data Stream (PDS) digital channel, the full excursion of the phase deviation, also called the peak-to-peak value, is two times the RMS value. The peak value equals the RMS value (i.e. signal is basically a square wave). For an analogue channel, when a single unmodulated carrier is present at a level sufficient to suppress the noise, the peak value of the deviation is approximately1.414 times the RMS value (i.e. signal is basically a sine wave). 2.3.4 Biphase-L Data Encoding A biphase-L data encoding scheme is used in the downlink for the processed 406 MHz data from processors. It is shown in Figure 2.5. Figure 2-5: Processed Data Encoding Scheme Data Bits

NRZ-L + Phase

Notes: Biphase-L is defined as a transition occurring at the centre of every bit period. Symbol "1" is transmitted as: "+ phase": the first part of the bit "- phase": the second part of the bit; and Symbol "0" is transmitted as: "- phase": the first part of the bit "+ phase": the second part of the bit

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Table 2.4: Cospas and Sarsat Output Parameters Parameter Unit Cospas Sarsat SARR-1 Sarsat SARR-2 Transmitted Signal Centre Frequency MHz 1544.5 Nominal Power Output of Transmitter W 4.0 7.2 4.0 EOL min Phase Jitter (in 50 Hz Bandwidth) o (RMS) ≤ 10 Occupied Bandwidth 1 (including Doppler) kHz ≤ 800 Modulation Type Linear Phase Modulation Nominal Composite Mod. Index rad (RMS) 0.69 to 0.87 0.70 ± 10% 0.347 to 0.476 406.05 MHz Repeater Channel Baseband Centre Frequency kHz 75.0 170.0 N/A Frequency Translation N/A Uninverted Uninverted N/A Nominal Modulation Index rad (RMS) 0.63 to 0.75 0.58 ± 10 % N/A 1 dB Bandwidth kHz

N/A PDS Channel Bit Rate bps 2400 ± 0.1% 2400±0.5% Nominal Modulation Index rad (RMS) 0.28 to 0.44 0.39 ± 10% 0.347 to 0.476 Data Encoding (see Figure 2.3) N/A Biphase-L Doppler Measurement Accuracy 2 Hz (RMS) ≤ 0.35 Time Tagging Accuracy 3 ms < 10 Frequency Measurement Period ms

Prob. of Good Signal Processing N/A

0.99 Note 1: The occupied bandwidth, defined by ITU Radio Regulation no. S1.153, remains within the 1,000 kHz allocated by the ITU in normal operating conditions. Note 2: Both payloads are accurate and stable such that the value of the received frequency at the spacecraft can be determined to the indicated accuracy from the data received by the LUT and from equations provided in section 4. Note 3: The Cospas satellites have an on-board clock providing absolute time which is maintained to the required accuracy. The SARP-2 and SARP-3 instruments on Sarsat satellites do not use an onboard absolute time clock. The absolute time tagging may be calculated by the ground stations using the on-board relative time scale and the time calibration (TCAL) routinely provided by the FMCC.

END OF SECTION 2 -

3-1

COSPAS-SARSAT REPEATERS Cospas Repater As shown in Figure 3.1, the Cospas SARR is redundantly configured and consists of the following units: two 4.0 W phase modulated L-band transmitters; and two Power, Telemetry and Command (PTC) units. Redundant units (A side and B side) are selected by commands from the ground which are processed by the PTC. The PTC also generates necessary voltages for the repeater system and contains interfaces to the spacecraft for all repeater telemetry and command channels. Figure 3-1: Cospas Repeater Functional Diagram A functional diagram of the Cospas transmitter is given in Figure 3.2. It employs a temperature controlled crystal oscillator. The linear modulator operates at a frequency of 386.125 MHz. After modulation, the output frequency is multiplied by 4 and the final amplification takes place on the 1544.5 MHz frequency. Before entering the linear phase modulator, modulation signals are amplified by a wideband linear amplifier. There is a two-level limiter in this amplifier, which prevents the instantaneous value of the summed modulating signal to exceed a certain level.

3-2

The modulation index adjustment is achieved by means of change of signal modulating voltage, which is subsequently passed to the input of the wideband linear amplifier. The Cospas 1544.5 MHz transmitter parameters given in Table 3.1 are in addition to those given in section 2. The downlink signal observed on the ground is illustrated in Figure 3.3. Table 3.1: Cospas 1544.5 MHz Transmitter Parameters Parameters Unit Values Downlink Baseband Spectrum N/A Figure 3.3 Incidental AM % ≤ 5 Spurious Output Level dBW ≤ -60 Frequency Stability Long term (5 yr.): Medium term (15 min.): Short term (0.1 sec.): kHz N/A N/A ± 1.5 5 x 10 -8 5 x 10 -10 Maximum Modulation Index Level: PDS: Composite: rad. (peak) rad. (peak) 0.92 (max. setting) 2.80 (hard limiter) Amplitude Ripple dB ≤ 2.5 Figure 3-2: Cospas 1544.5 MHz Transmitter Functional Diagram
Relative Signal Power (dB)

3-3

Figure 3-3: Typical Cospas 1544.5 MHz Observed Downlink Signal Frequency (kHz) - relative to downlink carrier centre frequency Sarsat Repeater SARR-1 (Sarsat-13 and earlier) As shown in Figure 3.4, the Sarsat SARR is redundantly configured and consists of the following units: two dual-conversion 406.05 MHz receivers (Sarsat-1,-2,-3 and -4 have only one 406.05 MHz receiver mounted on the A side); two 7.2 W phase modulated L-band transmitters; and two Power, Telemetry and Command units. Redundant units (A side and B side) are selected by commands from the ground which are processed by the PTC. The PTC also generates necessary voltages for the repeater system and contains interfaces to the spacecraft for all repeater telemetry and command channels.

3-4

Figure 3-4: Sarsat SARR-1 Functional Diagram Transmitter - A Side Transmitter - B Side 1544.5 MHz Output 406.05 MHz Receiver - A Side Local Oscillator 406.05 MHz Receiver - B Side Local Oscillator Power Telemetry and Command A - Side Power Telemetry and Command B - Side RF Switch RF Switch Filter 406 MHz Input 2.4 kbps from SARP To B Transmitter To B Transmitter 170 kHz Baseband 170 kHz BB 2.4 kbps 2.4 kbps Power Telemetry and Command To Spacecraft 3.2.1 Sarsat SARR-1 Receivers As shown in Figure 3.5, the 406 MHz receiver contains AGC and provides two outputs to drive the two transmitters. The Sarsat SARR receiver parameters given in Table 3.2 are in addition to those given in section 2.

3-5

Table 3.2: Sarsat SARR Receiver Parameters Parameters Unit Values for 406.05 MHz Receiver Nominal Input Level1 dBW

Maximum Input Level dBW

Dynamic Range dBW -164.3 to -137.2 Linearity N/A Note 2 Group Delay Slope µs/kHz

Image Rejection dB

AGC Time Constant ms 10 - 85 AGC Dynamic Range3 dB

50 Transient Recovery Time ms < 2 Frequency Stability Long term (2 yr.): Medium term (15 min.): Short term (1 sec.): N/A N/A N/A 1 x 10-6 1 x 10-10 1 x 10-10 Note 1: Nominal input level for 406 MHz is defined as the nominal noise of 1000 K plus ten simultaneous signals, each of -147.6 dBW. Note 2: With receivers in AGC mode and with nominal level settings, two out-of-band (for bandwidths in Figure 3.8) signals of -92 dBW at the receiver input, or two inband signals of -110 dBW, do not produce intermodulation products within the same baseband exceeding an output level of - 170 dBW with respect to the receiver input. Note 3: The peak modulation index limit of each repeater band is set such that any single inband signal of up to -110 dBW will not cause the composite modulation index limit to be reached before the AGC reduces the receiver output level back to nominal.

3-6

Figure 3-5: Sarsat SARR Receiver Functional Diagram Medium term frequency stability (over a 15 minute period) for the receiver is given as: Nominal Temperature: Mean Slope: ≤1 x 10-10/minute Residual Noise: ≤3 x 10-10 Full Temperature Range: Mean Slope: ≤1 x 10-9/minute Residual Noise: ≤3 x 10-9 The baseband filtering characteristic for the 406 MHz channel is given in Figure 3.6. Signals at frequencies indicated are attenuated by the corresponding amount with respect to the 0 dB level. Within this band, the receiver provides gain for those frequencies which fall within the band as specified in Table 2.4. Inband interfering signals in the band do not induce unwanted signals in the band exceeding - 175 dBW referred to the input and do not cause the modulation index to exceed the maximum level.

3-7

Figure 3-6: Sarsat SARR Receiver Bandpass Characteristics 3.2.2 Sarsat SARR-1 1544.5 MHz Transmitter As shown in Figure 3.7, each one of the transmitters has four inputs; one for each of the two 406 MHz receivers, one for the PDS channel and one spare. Sarsat transmitter parameters given in Table 3.3 below are in addition to parameters given in section 2. The downlink baseband frequency spectrum and an example of the signal observed on the ground are given in Figures 3.8 and 3.9. When the receiver input is illuminated by a sinusoidal signal at the maximum frequency and level, and by the processed data stream, no single discrete sideband is produced which exceed the limits shown in Figure 3.10. Noise-like emissions do not exceed the levels specified in Figure 3.10. With a receiver in AGC mode and nominal level setting, spurious output in the demodulated downlink spectrum do not exceed -175 dB with respect to a receiver input.

3-8

Table 3.3: Sarsat SARR-1 1544.5 MHz Transmitter Parameters Parameters Unit Values Downlink Baseband Spectrum N/A Figures 3.8 and 3.9 Incidental AM % ≤5 Spurious Output Level dBW Figure 3.10 Frequency Stability Long term (2 yr.): Medium term (15 min.): Short term (1 sec.): kHz N/A N/A ± 3.2 ≤ 1 x 10-10 ≤ 1 x 10-10 Maximum Modulation Index Level: 406.05: PDS: Composite: rad. (peak) rad. (peak) rad. (peak) 1.30 (hard limiter) 0.39 (max. setting) 2.10 (hard limiter) Amplitude Ripple dB ≤ 2.5 Figure 3-7: Sarsat SARR-1 1544.5 MHz Transmitter Functional Diagram Multiplier Oscillator Phase Modulator Filter Filter IF RF 1544.5 MHz Output Baseband Summer 406 MHz Receiver 2.4 kbps PDS 406 MHz Receiver A Side: Basebands B Side: Basebands SPARE

3-9

Figure 3-8: Sarsat SARR-1 Baseband Frequency Spectrum

3-10

Figure 3-9: Typical Sarsat SARR-1 1544.5 MHz Observed Downlink Signal

3-11

Figure 3-10: Sarsat SARR Transmitter Spurious Emission Limits Sarsat Repeater SARR-2 (Sarsat-14 and after) As shown in Figure 3.11, the Sarsat SARR-2 consists of the following modules: one Power, Telemetry and Command (PT&C) module; one Frequency Generator module; one SAW filter; and one phase modulated L-band transmitter module.

3-12

3.3.1 SARR-2 Power, Telemetry and Command The PT&C generates necessary voltages for the repeater system and contains the interfaces to the spacecraft for the repeater telemetry and command channels. Figure 3-11: Sarsat SARR-2 Functional Diagram 3.3.2 SARR-2 Frequency Generator In SARR-2, a portion of the transmitter has been separated into a module of its own. The module consists of a stable 10MHz reference and synthesizer to generate the L-Band (1544.5 MHz) carrier. This L-Band LO is then supplied to the phase modulator in the Transmit module where the baseband signal is modulated onto the carrier. The Sarsat SARR-2 transmitter functional diagram is presented in Figure 3.12 and includes the functionality in the frequency generator module. 3.3.3 SARR-2 SAW FILTER The SAW filter is placed between the frequency generator and the transmitter modules on the LO/Carrier signal path. The SAW filter is a band-pass filter used to reduce the out of band spurious and noise emission levels from the frequency generator module.

3-13

3.3.4 Sarsat SARR-2 1544.5 MHz Transmitter The Sarsat SARR-2 transmitter Functional Diagram is presented in Figure 3.12. The transmitter module has two inputs; one for the PDS channel and one for the L-Band LO input from the SAW filter. Sarsat SARR-2 transmitter parameters given in Table 3.4 below are in addition to parameters given in section 2. The downlink baseband frequency spectrum and an example of the signal observed on the ground are given in Figures 3.13 and 3.14. When the processed data stream is present, no single discrete sideband is produced which exceeds the limits shown in Figure 3.10. Noise-like emissions do not exceed the levels specified in Figure 3.10, excluding the near/in-band frequency range of 1544.5 ±10 kHz, and the range Fc ±10 kHz to Fc ±100 kHz. Noise-like emissions do not exceed -60dBW/Hz for the range Fc ±10 kHz to Fc ±100 kHz. Table 3.4: Sarsat SARR-2 1544.5 MHz Transmitter Parameters Parameters Unit Values Downlink Baseband Spectrum N/A Figures 3.13 and 3.14 Incidental AM % ≤5 Spurious Output Level dBW Figure 3.10 with exceptions for noise- like emissions stated above Frequency Stability Long term (7 yr.): Medium term (15 min.): Short term (1 sec.): kHz N/A N/A ± 3.2 ≤ 1 x 10-10 ≤ 1 x 10-10 Maximum Modulation Index Level: rad. (peak) 0.7 (hard limiter) Amplitude Ripple dB (peak to peak) ≤ 2.5

3-14

Figure 3-12: Sarsat SARR-2 1544.5 MHz Transmitter Functional Diagram Figure 3-13: Sarsat SARR-2 Baseband Frequency Spectrum

3-15

Figure 3-14: Typical Sarsat SARR-2 1544.5 MHz Observed Downlink Signal

END OF SECTION 3 - Relative Signal Power (dB) Frequency (kHz) - relative to downlink carrier centre

4-1

COSPAS-SARSAT SARPS Cospas SARP The Cospas SARP is composed of a Receiver Processor, a Frame Formatter (FF) and a memory unit. Each Cospas SARP is redundantly configured. The following satellites contain the indicated SARPs which are described in this document: Cospas-14 and follow on: SARP-2 Cospas satellites C-1 to C-10 have been gradually decommissioned from service. Cospas satellites C-11, C-12 and C-13 have not been commissioned. The SARP-2 has improved performance in system capacity, bandwidth and protection against interferers. Both long and short messages are supported by this processor. Cospas SARP-2 parameters given in Table 4.1 are in addition to those given in section 2. 4.1.1 Cospas SARP-2 Receiver Processor A functional diagram of the Receiver Processor is shown in Figure 4.1. The Receiver Processor unit is composed of the following: one dual-conversion receiver; one Analog to Digital (A/D) converter; one Search Unit; three Data Recovery Units (DRUs); one Control Unit; one Central Processor Unit; and Power, Telemetry and Command circuit

4-2

Table 4.1: Cospas SARP-2 Parameters Parameters Unit Values Receiver Centre Frequency - Mode 1 (selectable) Mode 2 Mode 3 MHz 406.0235 406.0300 406.0500 Receiver Bandwidth (1 dB) - Mode 1 (selectable) Mode 2 Mode 3 kHz

Receiver Dynamic Range dBW -161 to -138 Frequency Stability Long-term (5 yr.): Short-term (0.1 sec.): kHz N/A ± 1.5 1 x 10-10 Frequency of sub-carrier (406 MHz signals relay mode) kHz 75.0 Bit Error Rate1 N/A < 1 x 10-5 Output Data Rate bps 2,400 Time Measurement Increment ms

Ambiguity of Time Tagging Hrs

Number of DRUs N/A

Memory Capacity messages bits 2,000 460,800 Message Types Supported N/A Short and long Note 1: BER applies for signal level of -161 dBW and Receiver Noise Temperature of 600 K. Figure 4-1: Cospas SARP-2 Receiver Processor Functional Diagram

4-3

The analog output of the receiver is converted into a digital form by the analog to digital converter. The search unit performs spectrum analysis to determine frequency and amplitude. The spectrum analyser on commands from the ground, can analyze one of the three bands. When a signal is detected, the central processor assigns that signal to a DRU. On commands from the central processor, the DRU performs signal acquisition and demodulation, and determines the Doppler frequency of the received signal. In addition to controlling the functioning of the DRUs, the central processor also:

assigns DRUs to beacon signals;

checks the performance of the DRUs; and

performs self-testing.

This SARP-2 uses a new algorithm to protect the instrument against interferers. It is designed to avoid a continuous assignment of DRUs to interferer signals, thus making them available to process beacon signals. The control unit performs the following functions:

performance monitoring of the analogue receiver;

check out of the analogue receiver performance as well as that of the spectrum analyser; and

self checking. 4.1.2 Cospas SARP-2 Frame Formatter A functional diagram of the Frame Formatter (FF) is shown in Figure 4.2. The FF accepts all messages received from the DRUs and recorded messages are passed continuously to the modulator of the transmitter.

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Figure 4-2: Cospas SARP-2 Frame Formatter Functional Diagram Main Frame Memory 1 Main Frame Memory 2 Main Frame Memory 3 Processor

Processor

Output Interface

Input Interface

Adaptor

Digital Data from Receiver Processor Time Code Digital Data to Transmitter Telemetry Data 4.1.3 Cospas SARP-2 Output Format Beacon messages from the Cospas SARP-2 are transmitted in blocks of 25 words, as shown in the example of Figure 4.3. Prime format rules are: Zero words '000001'(Hex) are inserted at the end of each short message as necessary; Word # 00 = always frame sync '42BB1F'(Hex); DRU words are sequential and not interleaved; and Long and short beacon messages can be mixed. Bit formats for each type of message are shown in Figures 4.4 and 4.5. Words contain the following information: Word 0: Sync word 'D60' (Hex) followed by 6 bits as described in the figures and then 6 bits of level and parity. The 5 bit received level is given by: Level (dBW) = -161+L where L is the 5-bit level in decimal form.

4-5

Word 1: The Doppler count is followed by its parity bit. The Doppler frequency is given by: where N is the Doppler count in decimal form. The frequency at the input of the satellite receiver, Fin, is given by: Fin (Hz) = Fd + 406,010,000 Word 2: The time code followed by its parity bit. It is quantized in steps of 16 ms, synchronised with the beginning of the Doppler count and given as: Hours (5 bits): Minutes (6 bits) : seconds(6 bits): 16 ms (6 bits) The time given is 2hr 59min and 59 sec ahead of UTC (i.e. UTC = Cospas time - 2:59:59) Words 3 to 5: 72 bits of the beacon message. Word 6a: Last 16 bits of beacon short message followed by 8 zeros. Word 6b: 24 bits of beacon long message. Word 7a: Zero word '000001' (Hex) for short message. Word 7b: Last 24 bits of beacon long message. Fd (Hz) = 62,500 N

− 35,000

4-6

Figure 4-3: Example of a Cospas SARP-2 Output Message Word Word Content (Hex)

42BB1F

D60…

……

…… Short

…… Message

……

D60…

……

…… Long

…… Message

……

D60…

……

…… Long

…… Message

……

42BB1F Figure 4-4: Cospas SARP-2 Short Message Bit Format Word # MSB Word Content(24 bits) LSB

Sync word pseudo DRU latest RT/PB Parity level Parity (12 bits) (1b) (2b) (1b) (1b) (1b) (5b) (1b) Notes: (1) (2) (3) (4) (5) (5)

Doppler count (23 bits) Parity (1 bit) (note 7)

Time code (23 bits) Parity (1 bit) (note 7) hours : minutes : seconds : 16 ms (5 bits) (6 bits) (6 bits) (6 bits)

Format flag (1 bit)(note 6) Beacon data (23 bits)

Beacon data (24 bits)

Beacon data (24 bits) 6a Beacon data (16 bits) 8 0's 7a 'zero word' (24 bits) = 000001 (hex)

4-7

Figure 4-5: Cospas SARP-2 Long Message Bit Format Word # MSB Word Content(24 bits) LSB

Sync word pseudo DRU latest RT/PB Parity level Parity (12 bits) (1b) (2b) (1b) (1b) (1b) (5b) (1b) Notes: (1) (2) (3) (4) (5) (5)

Doppler count (23 bits) Parity (1 bit) (note 7)

Time code (23 bits) Parity (1 bit) (note 7) hours : minutes : seconds : 16 ms (5 bits) (6 bits) (6 bits) (6 bits)

Format flag (1 bit)(note 6) Beacon data (23 bits)

Beacon data (24 bits)

Beacon data (24 bits) 6b Beacon data (24 bits) 7b Beacon data (24 bits) Notes: (1) Pseudo-mode is not supported on Cospas satellites, beginning with Cospas-14. The value is defaulted to "0". (2) "01" = DRU1; "10" = DRU2; "11" = DRU3. (3) "1" = most recent message(playback); "0" = others. (4) "1" = real time message; "0" = playback message. (5) Parity bit on previous five bits: "1" = odd number of "1". (6) Format flag: "1" = long message; "0" = short message. (7) Parity bit in words 1 and 2:'1' with odd number of '1s' in the 23 bits of the Doppler count or the Time code. Sarsat SARP The following satellites contain the indicated SARPs which are described in this document: Sarsat-7: SARP-2 Sarsat-8: SARP-2 Sarsat-9: SARP-2 Sarsat-10: SARP-2 Sarsat-11: SARP-3 Sarsat-12: SARP-3 Sarsat-13: SARP-3 Sarsat-14: SARP-3 Sarsat-15: SARP-3 The SARP instruments on Sarsat satellites Sarsat-1 to Sarsat-6 have been decommissioned from service. 4.2.1 Sarsat SARP-2 The functional diagram of the SARP-2 Processor is shown in Figure 4.6. SARP-2 parameters given in Table 4.2 are in addition to those given in section 2.

4-8

Table 4.2: Sarsat SARP-2 Parameters Parameters Unit Values Receiver Centre Frequency - Mode 1 (selectable) Mode 2 Mode 3 MHz 406.0235 406.0300 406.0500 Receiver Bandwidth (1 dB) - Mode 1 (selectable) Mode 2 Mode 3 kHz

Receiver Dynamic Range dBW -161 to -138 Bit Error Rate1 N/A < 1 x 10-5 Output Data Rate bps

Time Measurement Increment ms 19.1 approx. Ambiguity of Time Tagging Hrs 44.5 approx. Signal Level Measurement Accuracy2 dBm +/- 2.0 Signal Level Measurement Quantization dBm 0.5 Number of DRUs N/A

Memory Capacity (short or long messages) messages bits

400k approx. Message Types Supported N/A Short and long Note 1: BER applies for signal level of -161 dBW and Receiver Noise Temperature of 300 K. Note 2: 1 to 2% of all signal level measurements provide erroneous information (i.e. the minimum allowable value is provided rather than the actual value).

4-9

Figure 4-6: Sarsat SARP-2 Functional Diagram 2.4 kbps PDS to SARR RF Input Power Supplies Telemetry Commands Frame Formatter and Memory Receiver Control Unit DRU 1 DRU 2 DRU 3 Search Unit A/D 4.2.1.1 Sarsat SARP-2 Receiver Processor The SARP-2 instrument has improved performance in system capacity, bandwidth and protection against interferers. Logic circuits using the Fast Fourier Transform algorithm perform signal searching by making a spectrum analysis of the receiver output (determination of frequency and level). The receiver is a temperature-compensated, constant-gain receiver. This processor uses a new algorithm to protect the instrument against interferers. It is designed to avoid a continuous assignment of DRUs to interferer signals, thus making them available to process beacon signals. To locate an interferer which has a stable frequency, the Control Unit can enable, on command from the ground, any one of the DRUs (but only at a time) to generate "pseudo-messages", (i.e. messages which do not have valid identification data, but do have valid time/frequency points), which can be specially processed by LUTs to locate interferers. The average time between pseudo- messages generated is at least 10 seconds. While the one DRU is in this special mode, the other two DRUs continue to process beacon signals as normal.

4-10

It has three DRUs to improve reliability and capacity of the system. Each DRU comprises a phaselock loop with new circuits that are mostly digital, a bit synchroniser using a new digital design and a formatter. The capacity of the memory has been increased to approximately 400 kbits allowing the storage of up to 2048 messages (long or short or pseudo-messages) for global area coverage. This instrument's mass memory operates similarly to the SARP-1 memory. The same five commands have the same effects. The capacity of the memory has been increased to approximately 400 kbits to take into account the storage of pseudo-messages when the instrument is used to locate interferers. To simplify the hardware associated with the reading of the messages, all messages, short or long, are stored in the same number of addresses. A short message is followed by a zero word to occupy the same memory space as a long message. 4.2.1.2 Sarsat SARP-2 Output Format Beacon messages from the Sarsat SARP-2 are transmitted in blocks of 25 words as shown in the example of Figure 4.7. Prime format rules are: Zero words '000001'(Hex) are inserted at the end of each short message as necessary; Word # 00 = always frame sync '42BB1F'(Hex); and If read continuous mode is active and if the oldest playback message has just been transmitted, a block of eight zero words will precede resumption of playback which will start with the first word of the most recently stored message. The bit format for both length of message formats are shown in Figures 4.8 and 4.9, where the Most Significant Bit (MSB) of Word 0 is transmitted first. All words contain the following information: Word 0: Sync word 'D60' (Hex) followed by 6 bits described in the figure and then the signal level. The received level is given by: Level (dBm) = 0.564L – 140 where L is the 6-bit level converted to decimal form Word 1: The time code is quantized in steps of 's' ms and synchronised with the beginning of the Doppler count. The last bit is a parity bit. The quantization is given by:

4-11

ms 19.096 Hz

s r ≈

= where Fr is frequency of oscillator (approx 5 203 205 Hz) The UTC time T is given by: T = To + 223ks + s(Md + 1) where s ≈ 19.096 ms ( the resolution time of the counter); Md = decimal value of the 23-bit on-board time code; To = UTC of an arbitrarily chosen reset to zero of the counter; and k = Number of resets to zero of the counter between time To and time T. The value of k is computed in ground processing, for each message, with a coarse estimate Te of T as the integer part of: ( ) T T s e o − ±

The coarse estimate Te can be obtained either by processing a time calibration beacon message from stored data or from the real time when processing local mode data. The time calibration beacon is described in C/S T.006. Words 2 to 4: 72 bits of the beacon message. Word 5a: Last 15 bits of beacon short message data followed by 9 zeros. Word 5b: 24 bits of beacon long message data. Word 6a and 7b: 23-bit Doppler word with parity. The frequency at the input of the satellite receiver, Fin, is given by: Fin = Fr (( aN) + b ) Hz where ;

3.05664845

× ≈ ×

b = 78 + 1

x 624 26 + + ≈

78 02564104137

. . ; Fr ≈5 203 205 Hz; and N = Doppler count in decimal form. Word 6b: Last 23 bits of beacon long message data followed by one zero. Word 7a: Zero word "000001 (Hex)". For pseudo-messages, the 13th bit of Word 0 is set. Pseudo-messages are short messages, having the bit format shown in Figure 4.8, but the beacon data is replaced by:

4-12

Words 2, 3 and 4: 0000 1111 0000 1111 0000 1111 Word 5: 0000 1111 0000 1110 0000 0000 Note: Fr is the frequency of the SARP Ultra Stable Oscillator. LEOLUTs should use a recent estimate of the USO frequency, as provided in a recent SARP calibration message (SIT 415) or as calculated by the LEOLUT, for determining the time and frequency of the beacon burst. To is the UTC of an arbitrarily chosen time of reset to zero of the SARP time counter. For calculating the time of a beacon burst, LEOLUTs should use a recent To value as provided in a recent SIT 415 message or as calculated by the LEOLUT. Figure 4-7: Example of a Sarsat SARP-2 Output Message Word Word Content (Hex)

42BB1F

D60…

……

…… Long

…… Message

……

D60…

……

…… Short

…… Message

……

D60…

……

…… Long

…… Message

……

42BB1F

D60…

…… Figure 4-8: Sarsat SARP-2 Short Message Bit Format

4-13

Word # MSB Word Content(24 bits) LSB

Sync word pseudo DRU Format latest RT/PB level (12 bits) (1b) (2b) (1b) (1b) (1b) (6b) Notes: (1) (2) (3) (4) (5)

Time code (23 bits) Parity (1 bit) (note 6)

Beacon data (24 bits)

Beacon data (24 bits) 5a Beacon data (15 bits) 9 0's 6a Doppler word (23 bits) Parity (1 bit) (note 6) 7a "zero word" (24 bits) = 000001 (hex) Figure 4-9: Sarsat SARP-2 Long Message Bit Format Word # MSB Word Content(24 bits) LSB

Sync word pseudo DRU Format latest RT/PB level (12 bits) (1b) (2b) (1b) (1b) (1b) (6b) Notes: (1) (2) (3) (4) (5)

Time code (23 bits) Parity (1 bit) (note 6)

Beacon data (24 bits)

Beacon data (24 bits) 5b Beacon data (24 bits) 6b Beacon data (23 bits) zero bit (1 bit) 7b Doppler word (23 bits) Parity (1 bit) (note 6) Notes : (1) "1" = pseudo-message; "0" = beacon message. (2) "01" = DRU1; "10" = DRU2; "11" = DRU3. (3) "1" = long message; "0" = short message. (4) "1" = most recent message(playback); "0" = others. (5) "1" = real time message; "0" = playback message. (6) Parity: "1" = odd number of "1s" in the 23-bit time code or the 23-bit Doppler code.

4-14

4.2.2 Sarsat SARP-3 The functional diagram of the SARP 3 Processor is shown in Figure 4.10. SARP-3 parameters given in Table 4.3 are in addition to those given in section 2. Table 4.3: Sarsat SARP-3 Parameters Parameters Unit Values Receiver Centre Frequency MHz 406.0500 Receiver Bandwidth (1 dB) kHz

Receiver Dynamic Range dBW -164 to -138 Bit Error Rate (See Note 1) N/A < 1 x 10-5 Output Data Rate bps 2399.8 Time Measurement Increment ms 20 approx. Ambiguity of Time Tagging Hrs 44.5 approx. Signal Level Measurement Accuracy dBm TBD Signal Level Measurement Quantization dBm TBD Number of DRUs N/A

Memory Capacity (short or long messages) messages bits 2048 (See Note 2) 400k approx. Message Types Supported N/A Short and long Notes: 1. BER applies for signal level of -164 dBW and Receiver Noise Temperature of 300 K. 2. The SARP-3 has a mode which increases the memory to 2,560 messages. This mode can only be activated on command by the payload provider. SARP-3 processors will include a capability to process a new type of Cospas-Sarsat distress beacon that would enhance performance by providing a better link budget. Such beacons are not yet available for operational use, however, technical details on their modulation characteristics may be obtained from the Cospas-Sarsat Secretariat.

4-15

Figure 4-10: Sarsat SARP-3 Functional Diagram 2.4 kbps PDS to SARR RF Input Power Supplies Telemetry Commands Frame Formatter and Memory Receiver Control Unit DRU 1 DRU 2 DRU 3 Search Unit A/D 4.2.2.1 Sarsat SARP-3 Receiver Processor The SARP-3 instrument has similar performance to the SARP-2 instrument. The basic structure of the format of the data it provides mimics the format provided by the SARP-2, however, there are a few minor changes in the position of some of the bits. The digital processing employed by the SARP-3 enable it to provide the S/No of beacon messages that it processes. Also, on command from the satellite operator, the instrument can be commanded to transmit House-Keeping (HK) messages in the 2.4 kbps PDS data stream. These messages are transmitted for reception by the French ground segment and should be ignored by all other LEOLUTs. HK messages are identified by the following: Word 2 = 110 011 100 011 111 000 000 000; and the BCH code provided in words 4 and 5 is consistent with the data in words 2, 3,4 and 5 that it protects. The Sarsat SARP-3 HK message structure is provided at Figure 4.14.

4-16

4.2.2.2 Sarsat SARP-3 Output Format Beacon messages from the Sarsat SARP-3 are transmitted in blocks of 25 words as shown in the example of Figure 4.11. Prime format rules are: Zero words 'H000001'(Hex) are inserted at the end of each short message as necessary; Word # 00 = always frame sync '42BB1F'(Hex); If read continuous mode is active and if the oldest playback message has just been transmitted, a block of eight zero words will precede resumption of playback which will start with the first word of the most recently stored message; and If no message must be transmitted (at the beginning when no message has been received or when the read continuous mode is inactive), blocks of eight zero words H000001 are transmitted. Real time messages are transmitted approximately 15 seconds after their reception by the SARP. The bit format for both length of message formats are shown in Figures 4.12 and 4.18, where the Most Significant Bit (MSB) of Word 0 is transmitted first. All words contains the following information: Word 0: Sync word 'HD60' (Hex) followed by 6 bits described in the figure and then the signal level. The received level, Pe, is given by: Pe (dBm) = - 140 + LEVEL* 0.55 where LEVEL is a value between 0 and 63 defined by final six bits in Word 0. Word 1: The time code is quantized in steps of 's' ms and synchronised with the beginning of the Doppler count. The last bit is a parity bit. The quantization, which is assigned the variable value s in the equations below, is defined by: ms

200,000 F 200,000 s

r ≈

= where Fr is the exact frequency of oscillator (the nominal frequency of the oscillator is approx 10 MHz) The UTC time T is given by: T = To + 223ks + s(Md + 1) Where Md = decimal value of the 23-bit on-board time code;

4-17

To = UTC of an arbitrarily chosen reset to zero of the counter; and k = Number of resets to zero of the counter between time To and time T. The value of k is computed in ground processing, for each message, with a coarse estimate Te of T as the integer part of: ( ) T T s e o − ±

The coarse estimate Te can be obtained either by processing a time calibration beacon message from stored data or from the real time when processing local mode data. The time calibration beacon is described in C/S T.006. Words 2 to 4: Message format followed by 71 bits of the beacon message. Word 5a: Last 16 bits of beacon short message data followed by 8 zeros. Word 5b: 24 bits of beacon long message data. Words 6a and 7b: 23-bit Doppler word with parity. The frequency at the input of the satellite receiver, Fin, is given by: Fo Fr *

.0 * Doppler Fo *

Fin       +

where the nominal USO frequency, Fo = 107 Hz Fr = exact frequency of the USO (if available) Doppler = signed integer value between –222 and +222-1 defined by 23 bits with two’s complement. Word 6b: Last 24 bits of beacon long message data. Word 7a: Zero word "H000001 (Hex)". Note: Fr is the frequency of the SARP Ultra Stable Oscillator. LEOLUTs should use a recent estimate of the USO frequency, as provided in a recent SARP calibration message (SIT 415) or as calculated by the LEOLUT, for determining the time and frequency of the beacon burst. To is the UTC of an arbitrarily chosen time of reset to zero of the SARP time counter. For calculating the time of a beacon burst, LEOLUTs should

4-18

use a recent To value as provided in a recent SIT 415 message or as calculated by the LEOLUT. Figure 4-11: Example of a Sarsat SARP-3 Output Message Word Word Content (Hex)

42BB1F

HD60…

……

…… Long

…… Message

……

HD60…

……

…… Short

…… Message

……

H000001

HD60…

……

…… Long

…… Message

……

H42BB1F

HD60…

…… . . .

4-19

Figure 4-12: Sarsat SARP-3 Short Message Bit Format Word # MSB Word Content(24 bits) LSB

Sync word S/No Type latest RT/PB level (12 bits) (3b) (1b) (1b) (1b) (6b) Notes: (1) (2) (3) (4)

Time code (23 bits) Parity (1 bit) (note 5)

Format Beacon data (23 bits) (1b) (note 6)

Beacon data (24 bits)

Beacon data (24 bits) 5a Beacon data (16 bits) 8 0's 6a Doppler word (23 bits) Parity (1 bit) (note 5) 7a "zero word" (24 bits) = H000001 (hex) Figure 4-13: Sarsat SARP-3 Long Message Bit Format Word # MSB Word Content(24 bits) LSB

Sync word S/No Type latest RT/PB level (12 bits) (3b) (1b) (1b) (1b) (6b) Notes: (1) (2) (3) (4)

Time code (23 bits) Parity (1 bit) (note 5)

Format Beacon data (23 bits) (1b) (note 6)

Beacon data (24 bits)

Beacon data (24 bits) 5b Beacon data (24 bits) 6b Beacon data (24 bits) 7b Doppler word (23 bits) Parity (1 bit) (note 5) Notes : (1) S/NO in 8 steps as defined in the following table: code S/NO code S/NO

32.3 (31 ≤ S/NO < 33.7)

45.2 (43.0 ≤ S/NO < 47.4)

34.8 (33.7 ≤ S/NO < 35.9)

50.1 (47.4 ≤ S/NO < 52.8)

37.5 (35.9 ≤ S/NO< 39.2)

55.5 (52.8 ≤ S/NO < 58.3)

41.1 (39.2 ≤ S/NO < 43.0)

62.1 (58.3 ≤ S/NO < 66) (2) "1" = Cospas-Sarsat Beacon (document C/S T.001); "0" = new type beacon. (3) "1" = most recent message(playback); "0" = others. (4) "1" = real time message; "0" = playback message. (5) Parity: "1" = odd number of "1s" in the 23-bit time code or the 23-bit Doppler word. (6) "1" = long message; "0" = short message.

4-20

Figure 4-14: Sarsat SARP-3 House-Keeping (HK) Message Bit Format Word # MSB Word Content(24 bits) LSB

HK data (24 bits)

110 011 100 011 111 000 000 000

HK data (24 bits)

HK data (13 bits) First ll bits of BCH

Last 10 bits of BCH HK data (14 bits)

HK data (24 bits)

HK data (24 bits) – END OF SECTION 4 –

5-1

COSPAS-SARSAT ANTENNAS Cospas Antennas As shown in Figure 5.1, two antennas (one receive and one transmit) have been provided on the spacecraft in support of the Cospas payload. 5.1.1 Cospas Receive Antennas Cospas receive antennas (SPA for 406 MHz) have the following characteristics: Polarisation: LHCP for 406 MHz Gain: As shown in Figures 5.2 Maximum and minimum contours of antenna gain referred to the receiver input when illuminated with a rotating linear source Axial ratio: As derived by the maximum and minimum contours on gain Figures Frequency: 406.05 MHz ±50 kHz 5.1.2 Cospas Transmit Antenna Cospas transmit antenna (SLA) has the following characteristics: Polarisation: LHCP Gain (referred to the transmitter output port): As shown in Figures 5.3 Minimum antenna gain on LHCP with an axial ratio ≤6 dB over 90% of region defined by 0º ≤ azimuth ≤ 360º and by 0º ≤ nadir ≤ 60º Axial ratio: As stated in gain Figure Frequency: 1544.5 MHz ±500 kHz

5-2

Figure 5-1: Cospas Antenna System Functional Diagram Figure 5-2: Cospas (SARP-2) 406 MHz Receive Antenna (SPA) Gain Pattern

5-3

Figure 5-3: Cospas (SARP-2) 1544.5 MHz Transmit Antenna (SLA) Gain Pattern Sarsat-TIROS Antennas As shown in Figure 5.5, three antennas (two receive and one transmit) have been installed on the spacecraft with necessary diplexers and filters in support of the Sarsat payload. 5.2.1 Sarsat-TIROS Receive Antennas The SARR Receive Antenna (SRA) is a coaxial quadrifilar antenna. The SARP receive antenna signal comes from the quadrifilar UHF Data collection system Antenna (UDA). Sarsat receive antennas have the following characteristics: Polarisation: RHCP Gain: Minimum gain (RHCP) over 90% As shown in Figures 5.5 to 5.6 Axial ratio: As derived by the maximum and minimum contours on gain Figures Frequency: SARR: 406.05 MHz ±50 kHz SARP: 406.05 MHz ±50 kHz 5.2.2 Sarsat-TIROS Transmit Antenna The SARR L-band transmit Antenna (SLA) is a quadrifilar antenna that has been optimised to produce a hemispherical pattern.

5-4

Sarsat transmit antenna has the following characteristics: Polarisation: LHCP Gain (referred to the transmitter output port): As shown in Figures 5.7 Axial ratio: As stated in gain Figure Frequency: 1544.5 MHz ±500 kHz Figure 5-4: Sarsat-TIROS Antenna System Functional Diagram SLA 1544.5 MHz Transmitter SRA 406.05 MHz SARR Input Filter UDA RF Switch SARP Input To Non-Sarsat payloads Filter Filter SLA 1544.5 MHz Transmitter SLA 1544.5 MHz Transmitter SRA 406.05 MHz SARR Input Filter SRA 406.05 MHz SARR Input Filter UDA RF Switch SARP Input To Non-Sarsat payloads Filter Filter

5-5

Figure 5-5: Sarsat-TIROS 406.05 MHz Receive Antenna (SRA) Gain Pattern (at receiver input) Antenna gain referenced to the receiver input, when illuminated with a rotating linear source.

5-6

Figure 5-6: Sarsat-TIROS SARP Receive Antenna (UDA) Gain Pattern (at receiver input) Antenna gain referenced to the receiver input, when illuminated with a rotating linear source.

Region defined by 0° ≤ azimuth ≤ 360° and 0° ≤ nadir ≤ 60°

5-7

Figure 5-7: Sarsat-TIROS 1544.5 MHz Transmit Antenna (SLA) Gain Pattern

Region defined by 0° ≤ azimuth ≤ 360° and 0° ≤ nadir ≤ 60° Sarsat-METOP Antennas As shown in Figure 5.8, two antennas (one receive and one transmit) have been installed on the spacecraft with necessary diplexers and filters in support of the Sarsat-METOP payload. 5.3.1 Sarsat-METOP Receive Antennas The Combined Receive Antenna (CRA) combines the receive antenna for SARP and SARR into one helical antenna. It is operating at 406 MHz and is connected to both SARR and SARP instruments. The CRA Antenna is deployable. Sarsat-METOP receive antenna (CRA) has the following characteristics: Polarisation: RHCP Gain: As shown in Figures 5.9 Axial ratio: As derived by the maximum and minimum contours on gain Figures Frequency: SARP/SARR: 406.05 MHz ±50 kHz

5-8

5.3.2 Sarsat-METOP Transmit Antenna The SARR L-band transmit Antenna (SLA) is a conventional quadrifilar helix that has been optimised to produce a hemispherical pattern. Sarsat-METOP transmit antenna has the following characteristics: Polarisation: LHCP Gain (referred to the transmitter output port): As shown in Figures 5.10 Axial ratio: As stated in gain Figure Frequency: 1544.5 MHz ±500 kHz Figure 5-8: Sarsat-METOP Antenna System Functional Diagram 1544.5 MHz Transmitter SLA Filter CRA Diplexer 406 MHz SARR Input To Non-Sarsat payloads Filter LNA 406 MHz SARP Input 1544.5 MHz Transmitter SLA Filter CRA Diplexer 406 MHz SARR Input To Non-Sarsat payloads Filter LNA 406 MHz SARP Input

5-9

Figure 5-9: Sarsat-METOP 406 MHz SARR and SARP Receive Antenna (CRA) Gain Pattern (at receiver input) Figure 5-10: Sarsat-METOP 1544.5 MHz Transmit Antenna (SLA) Gain Pattern Sarsat-NPOESS Antennas As shown in Figure 5.11, two antennas (one receive and one transmit) have been installed on the spacecraft with necessary accommodation hardware in support of the Sarsat-NPOESS payload.

Angle Off Nadir (Deg) Gain (dBiC) Predicted Average Gain (min of all phi cuts) Predicted Average Gain (max of all phi cuts) Predicted Average Gain (average of all phi cuts)

5-10

5.4.5 Sarsat-NPOESS Receive Antenna (description TBD by USA) Sarsat-NPOESS receive antenna has the following characteristics: Polarisation: RHCP Gain: As shown in Figure 5.12 for 95% of the azimuth angles and any nadir angle Center Frequency: 403 MHz ± 30 MHz (TBC by USA) 5.4.6 Sarsat-NPOESS Transmit Antenna (description TBD by USA) Sarsat-NPOESS transmit antenna has the following characteristics: Polarisation: LHCP Gain: As shown in Figure 5.13 for 95% of the azimuth angles and any nadir angle Axial ratio: For 99% of the azimuth angle and any nadir angle between 0 and 61.97 deg. Frequency: 1544.5 MHz ±500 kHz Figure 5-11: Sarsat-NPOESS Antenna System Functional Diagram

5-11

Figure 5-12: Sarsat-NPOESS Receive Antenna Gain Pattern (TBC by USA) SARSAT NPOESS Receive Antenna Gain

5 10 15 20 25 30 35 40 45 50 55 60 65 Nadir Angle (deg) Gain (dBiL) Maximum Gain (dBiL) Minimum Gain (dBiL) Figure 5-13: Sarsat-NPOESS Transmit Antenna Gain Pattern (TBC by USA) SARSAT NPOESS TRANSMIT ANTENNA GAIN

10 15 20 25 30 35 40 45 50 55 60 65 Nadir Angle (deg) Gain dBiL Minimum Gain (dBiL) – END OF SECTION 5 –

ANNEXES TO DESCRIPTION OF THE PAYLOADS USED IN THE COSPAS-SARSAT LEOSAR SYSTEM

A-1

ANNEX A: LIST OF ABBREVIATIONS AND ACRONYMS AGC Automatic Gain Control BTA Beacon Transmit Antenna (NOAA satellite) COSPAS COsmicheskaya Sistema Poiska Avarinykh Sudov (Russian equivalent to SARSAT) C/S Cospas-Sarsat dB decibel dBLi gain in decibels relative to a linear isotropic antenna dBm power in decibels relative to 1 milliwatt dBW power in decibels relative to 1 Watt DRU Data Recovery Unit EIRP Equivalent Isotropically Radiated Power FF Frame Formatter hex hexadecimal IF Intermediate Frequency K Kelvin (degrees) kbps kilo bits per second LHCP Left Hand Circular Polarisation LSB Least Significant Bit LUT Local User Terminal METOP European Meteorological Operational satellite programme MIRP Manipulated Information Rate Processor (on NOAA satellite) MSB Most Significant Bit N/A not applicable NOAA National Oceanic and Atmospheric Administration (USA) NPOESS National Polar-orbiting Operational Environmental Satellite System NRZ-L Non Return to Zero biphase-L data encoding

A-2

LIST OF ABBREVIATIONS AND ACRONYMS (Continued) PB Playback PDS Processed Data Stream PM Phase Modulation PTC Power, Telemetry and Command rad radian(s) RF Radio Frequency RHCP Right Hand Circular Polarisation RMS Root Mean Square RT Real Time SAR Search And Rescue SARP Search And Rescue Processor SARP-1 SARP with memory SARP-2 Second generation SARP with memory SARP-3 Third generation SARP with memory SARR Search And Rescue Repeater SARR-1 First generation of SARR SARR-2 Second generation of SARR (PDS channel only) SARSAT Search And Rescue Satellite Aided Tracking SBA NOAA S-band transmit antenna SLA SARR L-band transmit antenna SPA SARP receive antenna SRA SARR receive antenna TC Telemetry command from spacecraft interface to SAR payload TIP TIROS Information Processor (NOAA satellite) TIROS Television Infrared Observation Satellites TM Telemetry information from SAR payload to spacecraft interface UDA UHF data collection system antenna (NOAA satellite) UTC Universal Time Co-ordinated VCO Voltage Controlled Oscillator

END OF ANNEX A -

B-1

ANNEX B: COSPAS-SARSAT LEOSAR FREQUENCIES B.1 Introduction The 1992 ITU World Administrative Radio Conference (WARC 92) addressed the worldwide use and allocation of the radio spectrum, including mobile satellite services. Cospas-Sarsat, an international satellite system for search and rescue, provides a distress alerting and locating service using distress beacons operating on 406 MHz, a constellation of satellites, a number of ground receiving stations (called Local User Terminals, LUTs) and a network of Mission Control Centres which distribute the alert and location data to search and rescue authorities. The 406 MHz Cospas-Sarsat System has been adopted by the International Maritime Organization as part of the Global Maritime Distress and Safety System (GMDSS). B.2 Frequency Matters B.2.1 Frequency Requirements The Cospas-Sarsat Council considers it essential that the existing frequency allocations for Cospas-Sarsat remain in effect, because Cospas-Sarsat satellite payloads are already being built for use into the foreseeable future, with more than 30 ground receiving stations installed world- wide, any changes to operating frequencies would be very difficult to implement. The frequencies used by the Cospas-Sarsat LEOSAR System are identified in the radio regulations (Table B.1 refers), and the Cospas-Sarsat instruments using these frequency bands have been registered with the ITU. Prior to each open field test site transmission, the appropriate national authorities responsible for Cospas-Sarsat and radio emissions shall be notified. In order to keep the potential disturbance to the Cospas-Sarsat System to a minimum, these antenna tests shall be conducted using a beacon operating at its nominal repetition rate and coded with the test protocol of the appropriate type and format. Transmission of any continuous wave (CW) signal from a signal generator in the 406.0 - 406.1 MHz band is strictly forbidden.

B-2

B.2.2 Interference The international community has recognised the negative impact that interference could have on Cospas-Sarsat operations. To mitigate the risk, the ITU has approved a recommendation (ITU-R M.1478) which identifies the maximum interference levels which could be tolerated by Cospas and Sarsat SARP instruments. Table B-1: Cospas Sarsat LEOSAR Frequencies Frequencies Earth-to-space Space-to-earth Centre frequency Bandwidth ITU Radio Regulation Footnote Centre Frequency Bandwidth ITU Radio Regulation Footnote 406.05 MHz 100 kHz S5.266 & S5.267 1544.5 MHz 1000 kHz S5.354 & S5.356

END OF ANNEX B –
END OF DOCUMENT –

Cospas-Sarsat Secretariat 1250 René-Lévesque Blvd. West, Suite 4215, Montreal (Quebec) H3B 4W8 Canada Telephone: +1 514 500 7777 Fax: +1 514 500 7996 Email: mail@cospas-sarsat.int Website: http://www.cospas-sarsat.int

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assigns DRUs to beacon signals;

checks the performance of the DRUs; and

performs self-testing.

This SARP-2 uses a new algorithm to protect the instrument against interferers. It is designed to avoid a continuous assignment of DRUs to interferer signals, thus making them available to process beacon signals. The control unit performs the following functions:

performance monitoring of the analogue receiver;

check out of the analogue receiver performance as well as that of the spectrum analyser; and

s r ≈

× ≈ ×

r ≈

Fin       +

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