Ryan Malloy
4ed92efd69
Cospas-Sarsat specification summaries moved to reference/ for internal use only. Links updated to point to official cospas-sarsat.int site. The extracted images remain in public/ for use in other pages.
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2299 lines
62 KiB
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---
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title: "T011: Description Of The"
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description: "Official Cospas-Sarsat T-series document T011"
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sidebar:
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badge:
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text: "T"
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variant: "note"
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# Extended Cospas-Sarsat metadata
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documentId: "T011"
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series: "T"
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seriesName: "Technical"
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documentType: "specification"
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isLatest: true
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issue: 2
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revision: 6
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documentDate: "October 2025"
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originalTitle: "Description Of The"
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---
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> **📋 Document Information**
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>
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> **Series:** T-Series (Technical)
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> **Version:** Issue 2 - Revision 6
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> **Date:** October 2025
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> **Source:** [Cospas-Sarsat Official Documents](https://www.cospas-sarsat.int/en/documents-pro/system-documents)
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---
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# T011 - T011-OCT-23-2025.pdf
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**Pages:** 62
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---
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DESCRIPTION OF THE
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406-MHz PAYLOADS USED IN THE
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COSPAS-SARSAT GEOSAR SYSTEM
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C/S T.011
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Issue 2 – Revision 6
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DESCRIPTION OF THE 406-MHz PAYLOADS USED
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IN THE COSPAS-SARSAT LEOSAR SYSTEM
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History
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Issue
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Revision
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Date
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Comments
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Approved (CSC-21)
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Approved (CSC-23)
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Approved (CSC-25)
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Approved (CSC-27)
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Approved (CSC-33)
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Approved (CSC-41)
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Approved (CSC-45)
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Approved (CSC-49)
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Approved (CSC-51)
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Approved (CSC-53)
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Approved (CSC-59)
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Approved (CSC-61)
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Approved (CSC-62)
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Approved (CSC-64)
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Approved (CSC-69)
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Approved (CSC-71)
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Approved (CSC-73)
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TABLE OF CONTENTS
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Page
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History ................................................................................................................................................. i
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Table of Contents ................................................................................................................................. ii
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List of Figures
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................................................................................................................................ iv
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List of Tables
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................................................................................................................................. v
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1.
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INTRODUCTION .............................................................................................. 1-1
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1.1
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Overview .............................................................................................................. 1-1
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1.2
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Purpose ................................................................................................................. 1-1
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1.3
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Scope .................................................................................................................... 1-1
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1.4
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Reference Documents .......................................................................................... 1-1
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2.
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COSPAS-SARSAT PARAMETERS ................................................................ 2-1
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2.1
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406 MHz GEOSAR Payload Functional Description .......................................... 2-1
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2.2
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GEOSAR Orbit Summary .................................................................................... 2-2
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2.3
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GEOSAR System Coverage ................................................................................. 2-2
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3.
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COSPAS-SARSAT REPEATERS .................................................................... 3-1
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3.1
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GOES Repeater Functional Description .............................................................. 3-1
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3.1.1 GOES 15 and Before ................................................................................ 3-1
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3.1.2 GOES 16 and Later .................................................................................. 3-2
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3.2
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GOES Repeater Operating Modes ....................................................................... 3-3
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3.3
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GOES Repeater Spectrum Characteristics ........................................................... 3-4
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3.3.1 All GOES up to GOES-15 ....................................................................... 3-4
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3.3.2 GOES 16 and Later .................................................................................. 3-7
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3.4
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GOES Repeater Coverage Area ........................................................................... 3-7
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3.5
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GOES Repeater Performance Parameters ............................................................ 3-8
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3.5.1 GOES SAR Receiver Parameters ............................................................. 3-8
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3.5.2 GOES SAR Transmitter Parameters ...................................................... 3-10
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3.5.3 GOES SAR Antennas ............................................................................. 3-10
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4.
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INSAT/GSAT 406 MHz GEOSAR REPEATER ............................................ 4-1
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4.1
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INSAT/GSAT Repeater Functional Description .................................................. 4-1
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4.2
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INSAT/GSAT Repeater Operating Modes .......................................................... 4-2
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4.3
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INSAT/GSAT Repeater Spectrum Characteristics .............................................. 4-2
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4.4
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INSAT/GSAT Repeater Coverage Area .............................................................. 4-4
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4.5
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INSAT/GSAT Repeater Performance Parameters ............................................... 4-6
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4.6
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INSAT/GSAT SAR Antennas .............................................................................. 4-6
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5.
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ELECTRO-L GEOSAR REPEATER .............................................................. 5-1
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5.1
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Repeater Functional Diagram Description ........................................................... 5-1
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5.2
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Electro-L Repeater Operating Modes .................................................................. 5-2
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5.3
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Electro-L Repeater Baseband Spectrum .............................................................. 5-3
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5.4
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Electro-L Repeater Coverage Area ...................................................................... 5-5
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5.5
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Electro-L Repeater Performance Parameters ....................................................... 5-6
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5.5.1 Electro-L SAR Receiver Parameters ........................................................ 5-6
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5.5.2 Electro-L SAR Transmitter Parameters ................................................... 5-8
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5.5.3 Electro-L SAR Antennas .......................................................................... 5-9
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6.
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MSG 406 MHz GEOSAR REPEATER ........................................................... 6-1
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6.1
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MSG Repeater Functional Description ................................................................ 6-1
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6.2
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MSG Repeater Operating Modes ......................................................................... 6-2
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6.3
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MSG Repeater Spectrum Characteristics ............................................................. 6-2
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6.3
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MSG Repeater Coverage Area ............................................................................. 6-5
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6.4
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MSG Repeater Performance Parameters .............................................................. 6-5
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6.5
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MSG SAR Antennas ............................................................................................ 6-6
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6.5.1 MSG SAR Receive Antenna .................................................................... 6-7
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6.5.2 MSG SAR Transmit Antenna .................................................................. 6-7
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7.
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LOUCH-5A GEOSAR REPEATER ................................................................ 7-1
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7.1
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Louch-5A Repeater Functional Description ........................................................ 7-1
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7.2
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Louch-5A Repeater Operating Modes ................................................................. 7-1
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7.3
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Louch-5A Spectrum Characteristics .................................................................... 7-1
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7.4
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Louch-5A Coverage Area .................................................................................... 7-2
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7.5
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Louch-5A Repeater Performance Characteristics ................................................ 7-2
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7.6
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Louch-5A SAR Antennas ..................................................................................... 7-4
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8.
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MTG 406 MHZ GEOSAR REPEATER .......................................................... 8-1
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8.1
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MTG Repeater Functional Description ................................................................ 8-1
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8.2
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MTG Repeater Operating Modes ......................................................................... 8-1
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8.3
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MTG Repeater Spectrum Characteristics ............................................................. 8-2
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8.4
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MTG Repeater Coverage Area ............................................................................. 8-4
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8.5
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MTG Repeater Performance Parameters .............................................................. 8-4
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8.6
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MTG SAR Antennas ............................................................................................ 8-4
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LIST OF FIGURES
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Figure 2-1: GEOSAR Payload Functional Diagram .................................................................... 2-2
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Figure 3-1: GOES-15 and before Search and Rescue Repeater Functional Diagram ................ 3-1
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Figure 3-2: GOES-16-17 Repeater Block Diagram ..................................................................... 3-2
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Figure 3-3: SAR Part of SAR/DCPR Receiver Block Diagram .................................................. 3-3
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Figure 3-4: GOES (15 and Earlier) L-Band Transmitter Output Spectral Occupancy ................ 3-5
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Figure 3-5: For all GOES up to GOES-15: Narrow Band Baseband Spectrum .......................... 3-5
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Figure 3-6: GOES (All) Wide Band Baseband Spectrum ........................................................... 3-6
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Figure 3-7: GOES-16 Downlink Spectrum .................................................................................. 3-7
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Figure 3-8: GOES-E and GOES-W 0o Elevation Coverage Contours ......................................... 3-8
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Figure 3-9: GOES Through GOES-15 Receive Antenna Pattern at 406.05 MHz ..................... 3-11
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Figure 3-10: GOES Through GOES-15 Transmit Antenna Pattern at 1544.5 MHz ................. 3-12
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Figure 3-11: Typical GOES-16 and GOES-17 Receive Antenna Pattern at 406 MHz ............. 3-12
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Figure 3-12: Typical GOES-16 and 17 SAR Transmit antenna measured at 1544 MHz .......... 3-13
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Figure 4-1: INSAT/GSAT SAR / DRT Repeater Functional Block Diagram ............................. 4-1
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Figure 4-2: INSAT Transmitter Output Spectral Occupancy with No Test Signal ..................... 4-3
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Figure 4-3: GSAT Transmitter Output Spectral Occupancy with No Test Signal ...................... 4-3
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Figure 4-4: INSAT-3D 0-Degree Elevation Angle ...................................................................... 4-4
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Figure 4-5: INSAT-3DR 0-Degree Elevation Angle ................................................................... 4-4
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Figure 4-6: GSAT-17 0-Degree Elevation Angle ........................................................................ 4-5
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Figure 4-7: INSAT-3DS 0-Degree Elevation Angle ................................................................... 4-5
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Figure 4-8: INSAT-3D SASR 406.05 MHz Receive Antenna Contour Pattern .......................... 4-7
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Figure 4-9: INSAT-3DR SASR 406.05 MHz Receive Antenna Contour Pattern ....................... 4-7
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Figure 4-10: GSAT-17 SAR 406.05 MHz Receive Antenna Contour Pattern ............................ 4-8
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Figure 4-11: INSAT-3DS SASR 406.05 MHz Receive Antenna Contour Pattern ..................... 4-8
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Figure 4-12: INSAT-3D Transmit Antenna Contour Pattern ...................................................... 4-9
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Figure 4-13: INSAT-3DR Transmit Antenna Contour Pattern .................................................... 4-9
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Figure 4-14: GSAT-17 Transmit Antenna Contour Pattern ...................................................... 4-10
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Figure 4-15: INSAT-3DS Transmit Antenna Contour Pattern .................................................. 4-10
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Figure 5-1: Electro-L SAR Functional Diagram (Linear Phase Modulation Repeater) .............. 5-2
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Figure 5-2: Electro-L SAR Functional Diagram (Frequency Translation Repeater) .................. 5-3
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Figure 5-3: Spectrum Occupancy of Downlink Signal in WB Mode Spanned 300 kHz Around
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1544.5 MHz .......................................................................................................... 5-4
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Figure 5-4: Spectrum Occupancy of Downlink Signal in NB Mode Spanned 1 MHz Around 1544.5
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MHz ...................................................................................................................... 5-4
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Figure 5-5: Spectrum Occupancy of Downlink Signal Centred at 1544.5 MHz. Electro-L No.4 5-
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Figure 5-6: Electro-L 0o Elevation Angle Footprint (Electro- L No 2, 3 and 4) ......................... 5-5
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Figure 5-7: Electro-L SAR Receiver Bandpass Filter Amplitude-Frequency Response (Linear
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Phase Modulation Repeater NB Mode) ............................................................... 5-7
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Figure 5-8: Electro-L SAR Receiver Bandpass Filter Amplitude-Frequency Response (Linear
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Phase Modulation Repeater WB Mode) ............................................................... 5-7
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Figure 5-9: Electro-L SAR Receiver Bandpass Filter Amplitude-Frequency Response (Frequency
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Translation Repeater) ........................................................................................... 5-8
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Figure 6-1: MSG Search and Rescue Repeater Functional Diagram .......................................... 6-1
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Figure 6-2: MSG L-Band Transmitter Output Spectral Occupancy ............................................ 6-2
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Figure 6-3: Measured Pass-Band of MSG Transponder .............................................................. 6-3
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Figure 6-4: MSG Transmitter LO Phase Noise Spectrum Plot .................................................... 6-4
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Figure 6-5: MSG 5 o Elevation Angle Coverage Contour ........................................................... 6-5
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Figure 6-6: MSG SAR Receive Antenna Pattern ........................................................................ 6-8
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Figure 6-7: MSG SAR Transmit Antenna Pattern ....................................................................... 6-9
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Figure 7-1: Louch-5A Combined SAR and EDDN Transponder ................................................ 7-1
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Figure 7-2: Louch-5A Transmitter Spectrum Occupancy ........................................................... 7-2
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Figure 7-3: Louch-5A Coverage Zones for 0, 5 and 10 Degrees of Elevation Angle ................. 7-3
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Figure 7-4: Louch-5A Receive Antenna Pattern at 406.05 MHz ................................................ 7-5
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Figure 7-5: Louch-5A Transmit Antenna Pattern at 1544.5 MHz ............................................... 7-5
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Figure 8-1: MTG SAR Repeater Functional Block Diagram ...................................................... 8-1
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Figure 8-2: MTG Repeater Output Spectrum (Narrowband Mode) ............................................ 8-2
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Figure 8-3: MTG Repeater Output Spectrum (Wideband Mode) ................................................ 8-2
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Figure 8-4: MTG SAR Repeater Narrowband Filter Performance .............................................. 8-3
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Figure 8-5: MTG SAR Repeater Wideband Filter Performance ................................................. 8-3
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Figure 8-6: MTG UHF-Band Antenna Co-Polar Amplitude Pattern (Antenna Gain in dB Relative
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to the Peak Gain of 14.2 dBi; Red Circle Shows the Earth) ................................. 8-5
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Figure 8-7: MTG L-Band Antenna Co-Polar Amplitude Pattern (Antenna Gain in dB Relative to
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the Peak Gain of 14.2 dBi; Red Circle Shows the Earth) ..................................... 8-5
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LIST OF TABLES
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Table 3.1: GOES Repeater Operating Modes .............................................................................. 3-4
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Table 3.2: GOES SAR Receiver Parameters ............................................................................... 3-9
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Table 3.3: GOES SAR Transmitter Parameters ......................................................................... 3-10
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Table 4.1: INSAT/GSAT Repeater Operating Modes ................................................................. 4-2
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Table 4.2: INSAT/GSAT Repeater Performance Parameters ...................................................... 4-6
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Table 5.1: Electro-L Repeater Operating Modes ......................................................................... 5-2
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Table 5.2: Electro-L SAR Receiver Parameters .......................................................................... 5-6
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Table 5.3: Electro-L SAR Transmitter Parameters ...................................................................... 5-8
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Table 6.1: MSG Transmitter LO Phase Noise ............................................................................. 6-4
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Table 6.2: MSG SAR Repeater Performance Parameters ........................................................... 6-6
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Table 7.1: Louch-5A SAR Receiver Parameters ......................................................................... 7-3
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Table 7.2: Louch-5A SAR Transmitter Parameters ..................................................................... 7-4
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Table 8.1: MTG SAR Repeater Performance Parameters ........................................................... 8-4
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1-1
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1.
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INTRODUCTION
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1.1
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Overview
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The Cospas-Sarsat Space Segment consists of satellites in low earth orbit (LEO) equipped with
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search and rescue (SAR) instruments. The LEO satellites are complemented by satellites in
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geostationary earth orbit (GEO) with their respective SAR instruments. These geostationary
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search and rescue (GEOSAR) instruments are currently flown on USA and Indian spacecraft, and
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it is anticipated that they will also be flown on Russian and EUMETSAT spacecraft in the near
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future. The 406 MHz data received from these instruments are processed by Cospas-Sarsat Ground
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Segment equipment and provided to SAR agencies. This document provides a description of the
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GEOSAR instruments carried on board these spacecraft. The description of the Cospas-Sarsat
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LEO Space Segment is provided in document C/S T.003.
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1.2
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Purpose
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The purpose of this document is to describe the functionality and performance parameters for each
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GEOSAR instrument. The document is intended to be used to ensure the necessary compatibility
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for the 406 MHz beacon to satellite uplink and compatibility for the satellite to geostationary local
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user terminal (GEOLUT) downlink. The document is not intended for use as a specification for
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procurement of hardware for GEOSAR satellite repeaters.
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1.3
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Scope
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This document presents a technical description of the GEOSAR repeaters used in the Cospas-
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Sarsat system. Section 2 provides a general overview of the GEOSAR repeater function. Sections
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3, 4, 5, and 6 provide descriptions of the repeaters on the USA, Russian, Indian, and EUMETSAT
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satellites.
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1.4
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Reference Documents
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The following documents contain useful information to the understanding of this document.
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C/S T.001, Specification for Cospas-Sarsat 406 MHz Distress Beacons
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C/S T.003, Description of the Payloads used in the Cospas-Sarsat LEOSAR System
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C/S T.009, Cospas-Sarsat GEOLUT Specification and Design Guidelines
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C/S T.010, Cospas-Sarsat GEOLUT Commissioning Standard
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C/S G.003, Introduction to the Cospas-Sarsat System
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C/S S.011, Cospas-Sarsat Glossary
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1-2
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- END OF SECTION 1 -
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2-1
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2.
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COSPAS-SARSAT PARAMETERS
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The Cospas-Sarsat GEOSAR Space Segment consists of SAR instruments on board satellites in
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geostationary orbit. The SAR instruments are radio repeaters that receive distress beacon signals
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in the 406 - 406.1 MHz band and relay these signals to GEOLUTs for processing beacon
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identification and associated data. A description of the Cospas-Sarsat beacon signal parameters
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and data protocols is provided in reference documents C/S T.001 and C/S T.018. The series of
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satellites with GEOSAR instruments currently in use are shown below.
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GEOSAR Satellite series
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Country/Organization
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GOES
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USA
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INSAT
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India
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MSG
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EUMETSAT
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MTG
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EUMETSAT
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Electro-L
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Russia
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Louch
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Russia
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The detailed list of GEOSAR payloads and their current operational status is available on the
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Cospas-Sarsat
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website
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at
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https://www.cospas-sarsat.int/en/system/space-segment-status-
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pro/current-space-segment-status-and-sar-payloads-pro.
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2.1
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406 MHz GEOSAR Payload Functional Description
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A functional diagram of SAR instruments on GEOSAR spacecraft is shown in Figure 2.1. The
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GEOSAR instruments were independently developed and integrated into spacecraft that have
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different mission requirements. This has resulted in differences in repeater designs that affect the
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output signal as described in sections 3, 4, 5, 6, 7 and 8. These differences must be considered in
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developing a GEOLUT.
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The GEOSAR repeater receives 406 MHz beacon signals within the field of view of the 406 MHz
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receive antenna beam. The beacon signals are processed by the repeater and transmitted on the
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downlink signal for reception by a GEOLUT. The downlink center frequency and antenna pattern
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characteristics vary among the different repeater implementations as described in subsequent
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sections of this document.
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2-2
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Figure 2-1: GEOSAR Payload Functional Diagram
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2.2
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GEOSAR Orbit Summary
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Each of the GEOSAR satellites with operational payloads in a geostationary orbit with an orbital
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period of 24 hours with nominal parameters available on the Cospas-Sarsat website at
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https://www.cospas-sarsat.int/en/system/space-segment-status-pro/current-space-segment-status-
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and-sar-payloads-pro.
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2.3
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GEOSAR System Coverage
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The 406 MHz coverage area for the on-orbit operational GEOSAR payloads (using a nominal
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GEOSAR 5-degree elevation) is available on the Cospas-Sarsat website at https://www.cospas-
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sarsat.int/en/system/detailed-leosar-geosar-system-description/geosar-satellite-coverage.
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- END OF SECTION 2 -
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3-1
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3.
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COSPAS-SARSAT REPEATERS
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3.1
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GOES Repeater Functional Description
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3.1.1
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GOES 15 and Before
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A functional diagram of the GOES SAR repeater is shown in Figure 3.1. The repeater is
|
||
redundantly configured and consists of the following units:
|
||
|
||
two 406 MHz low noise amplifiers (shared with another satellite subsystem);
|
||
two dual-conversion 406 MHz receivers;
|
||
two 3-watt phase modulated L-Band transmitters;
|
||
one 406 MHz receive antenna and one 1544.5 MHz transmit antenna; and
|
||
command and telemetry points interfaced with the spacecraft telemetry and
|
||
command subsystem.
|
||
|
||
|
||
Figure 3-1: GOES-15 and before Search and Rescue Repeater
|
||
Functional Diagram
|
||
|
||
The 406 MHz signals from Cospas-Sarsat distress beacons are received on the UHF antenna
|
||
and fed through the antenna diplexer and switch to a low noise amplifier in one of the
|
||
redundant pair of Data Collection Platform Repeaters (DCPR). The DCPR low noise
|
||
amplifiers are used as part of the SAR implementation to accommodate circuit efficiency on
|
||
|
||
|
||
|
||
3-2
|
||
|
||
|
||
|
||
the spacecraft. The low noise amplifier outputs are connected to the redundant pair of SAR
|
||
receivers. The signal applied to the selected receiver is down-converted for bandpass filtering
|
||
in accordance with one of two commandable bandwidth modes; a narrow band mode of
|
||
20 kHz or a wide band mode of 80 kHz. The filtered output signal is further down-converted
|
||
to near baseband and fed through amplifiers to the SAR transmitter. The overall gain of the
|
||
SAR receiver can be command selected into a fixed gain or Automatic Level Control (ALC)
|
||
mode.
|
||
|
||
The outputs of the receivers are provided to the redundant pair of SAR transmitters. The
|
||
selected SAR transmitter phase modulates the signal, multiplies the signal to 1544.5 MHz,
|
||
and amplifies the modulated carrier to 3 Watts. The phase modulated signal has the nominal
|
||
modulation index set such that the carrier suppression is 3 dB with the receiver in the ALC
|
||
mode or with the receiver in the fixed gain mode operating with two nominal beacon signals
|
||
plus the noise. A baseband limiter restricts the modulation index from exceeding 2 radians.
|
||
The transmitter output is applied through a 4 MHz bandwidth filter to the helical antenna and
|
||
radiated with an effective radiated isotropic power (EIRP) of +15.0 dBW.
|
||
|
||
3.1.2
|
||
GOES 16 and Later
|
||
The GOES-R and GOES-S (GOES-16 and GOES-17 after launch) repeater is part of the
|
||
SAR/DCPR system. Figure 3.2 shows a high-level view of the repeater and the SAR part of
|
||
the SAR/DCPR receiver.
|
||
|
||
|
||
Figure 3-2: GOES-16-17 Repeater Block Diagram
|
||
|
||
|
||
|
||
|
||
|
||
3-3
|
||
|
||
|
||
|
||
Figure 3-3: SAR Part of SAR/DCPR Receiver Block Diagram
|
||
|
||
In the GOES 16-17 series of spacecraft, the SAR repeater is shared with the data Collection
|
||
platform (DCPR) as in previous GOES spacecraft. There are redundant receivers, a choice
|
||
between fixed gain and ALC modes, and a frequency translation scheme. Frequency
|
||
translation means that there is no modulator in the SAR receiver and the UHF input signal is
|
||
first frequency translated by a mixer down to 30.55 MHz for filtering and then frequency
|
||
translated via another mixer up to 1544.55 MHz by another LO. Figure 3.3 shows the 2 local
|
||
oscillators with the 1514 MHz oscillator providing low side injection, so the downlink spectra
|
||
is not reversed as it would be if this LO ‘s frequency were higher than the output frequency.
|
||
Notable is a new downlink frequency, 1544.55 MHz as opposed to the usual 1544.50 MHz in
|
||
previous GOES, and a no narrow band mode. This was done to achieve a better G/T and a
|
||
steeper filter skirt for the UHF input which will help in rejecting signals which are close to
|
||
the UHF frequency. The receiver is commandable into a fixe gain mode or an ALC mode, as
|
||
in previous GOES.
|
||
3.2
|
||
GOES Repeater Operating Modes
|
||
The GOES repeater has redundant low noise amplifiers, receivers, and transmitters that can be
|
||
selected to define a complete repeater configuration. A specific repeater configuration can be
|
||
operated in the modes described in Table 3.1. GOES-16 and all follow on GOES will have only
|
||
wide band modes.
|
||
|
||
|
||
|
||
|
||
|
||
3-4
|
||
|
||
|
||
|
||
Table 3.1: GOES Repeater Operating Modes
|
||
|
||
Mode
|
||
Band Center
|
||
Frequency
|
||
(MHz)
|
||
GOES spacecraft
|
||
up to GOES-15
|
||
Receiver 3 dB
|
||
Bandwidth (kHz)
|
||
GOES-16 and later
|
||
Receiver 3 dB
|
||
Bandwidth (kHz)
|
||
Narrow Band with ALC
|
||
406.025
|
||
|
||
N/A
|
||
Narrow Band Fixed Gain
|
||
406.025
|
||
|
||
N/A
|
||
Wide Band with ALC
|
||
406.050
|
||
|
||
|
||
Wide Band Fixed Gain
|
||
406.050
|
||
|
||
|
||
3.3
|
||
GOES Repeater Spectrum Characteristics
|
||
3.3.1
|
||
All GOES up to GOES-15
|
||
The spectral occupancy of the transmitted signal with the repeater in the wide band mode is
|
||
shown in Figure 3.4. This output spectrum, which applies the GOES spacecraft up to GOES-
|
||
15, therefore, represents the case of maximum spectrum occupancy. The spectrum plot was
|
||
taken at a received intermediate frequency of 44.5 MHz that is equivalent to a transmitted
|
||
frequency of 1544.5 MHz spectrum width. The narrow band spectrum is shown in
|
||
Figure 3.3a. The wide band spectrum is shown in Figure 3.3b.
|
||
|
||
The baseband spectral characteristics are shown in Figures 3.5 and 3.6. The received
|
||
406 MHz beacon signals are filtered and translated to a baseband frequency prior to phase
|
||
modulation in the transmitter. The modulation plan is such that a signal received at
|
||
406.000 MHz becomes zero Hz in the baseband spectrum. A Cospas-Sarsat beacon received
|
||
at 406.025 MHz will be at 25 kHz in the baseband spectrum. The 20 kHz and 80 kHz
|
||
bandpass filters control the baseband spectrum width. The narrow band spectrum is shown
|
||
in Figure 3.5. The wide band spectrum is shown in Figure 6.
|
||
|
||
|
||
|
||
3-5
|
||
|
||
|
||
|
||
Figure 3-4: GOES (15 and Earlier) L-Band Transmitter Output Spectral Occupancy
|
||
|
||
|
||
|
||
Figure 3-5: For all GOES up to GOES-15: Narrow Band Baseband Spectrum
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
3-6
|
||
|
||
Figure 3-6: GOES (All) Wide Band Baseband Spectrum
|
||
|
||
|
||
3-7
|
||
|
||
3.3.2
|
||
GOES 16 and Later
|
||
Figure 3-7: GOES-16 Downlink Spectrum
|
||
3.4
|
||
GOES Repeater Coverage Area
|
||
The zero-degree elevation angle coverage contour for the GOES-E and two GOES-W satellites is
|
||
shown in Figure 3.4. The receive and transmit antennas are broad beam earth coverage types.
|
||
Therefore, the coverage patterns in Figure 3.8 apply to both the receive and transmit functions.
|
||
|
||
|
||
|
||
3-8
|
||
|
||
|
||
|
||
Figure 3-8: GOES-E and GOES-W 0o Elevation Coverage Contours
|
||
|
||
3.5
|
||
GOES Repeater Performance Parameters
|
||
3.5.1
|
||
GOES SAR Receiver Parameters
|
||
The receiver parameters are shown in Table 3.2.
|
||
|
||
|
||
|
||
|
||
|
||
3-9
|
||
|
||
|
||
|
||
Table 3.2: GOES SAR Receiver Parameters
|
||
|
||
Parameter
|
||
Unit All GOES up to GOES-15
|
||
Values
|
||
GOES-16 and later
|
||
Values
|
||
Nominal Input Level at Antenna
|
||
dBW
|
||
-173.1
|
||
-173.1
|
||
System Noise Temperature
|
||
(referred to preamp input)
|
||
K
|
||
|
||
|
||
G/T
|
||
dB/K
|
||
-18.5
|
||
>-15.5
|
||
(-13.3 for GOES-16)
|
||
Receiver Bandpass Characteristic
|
||
Narrow Band Mode
|
||
(relative to 406.025 MHz)
|
||
Wide Band Mode
|
||
(relative to 406.05 MHz)
|
||
|
||
kHz
|
||
|
||
|
||
|
||
kHz
|
||
6.0 (1 dB BW)
|
||
10.0 (3 dB BW)
|
||
20.0 (20 dB BW)
|
||
|
||
30.0 (1 dB BW)
|
||
40.0 (3 dB BW)
|
||
50.0 (20 dB BW)
|
||
|
||
No narrow band mode
|
||
|
||
|
||
>80 (1 dB BW)
|
||
<100 (3 dB BW)
|
||
<130 (20 dB BW)
|
||
<180 (40 dB BW)
|
||
<230 (50 dB BW)
|
||
Dynamic Range
|
||
dB
|
||
15
|
||
|
||
Group Delay
|
||
(over 4 kHz)
|
||
s/kHz
|
||
13
|
||
|
||
Image Rejection
|
||
dB
|
||
|
||
70 @ ±21.4 MHz
|
||
AGC Time Constant
|
||
ms
|
||
40
|
||
|
||
Frequency Stability
|
||
Frequency Conversion
|
||
Oscillators (over 0.25 s)
|
||
|
||
N/A
|
||
|
||
1 x 10-9
|
||
|
||
|
||
Note 1:
|
||
Nominal input level at antenna from 5 Watt beacon located at 45° elevation angle to
|
||
the satellite. Includes 4.1 dB polarization loss.
|
||
|
||
|
||
|
||
|
||
|
||
3-10
|
||
|
||
|
||
|
||
3.5.2
|
||
|
||
GOES SAR Transmitter Parameters
|
||
|
||
The transmitter parameters are shown in Table 3.3.
|
||
|
||
Table 3.3: GOES SAR Transmitter Parameters
|
||
|
||
|
||
Parameter
|
||
Unit
|
||
All GOES up to
|
||
GOES-15 Values
|
||
GOES-16 and later
|
||
Values
|
||
Centre Frequency
|
||
MHz
|
||
1544.5
|
||
1544.55
|
||
Output Power of Transmitter
|
||
W
|
||
3.0
|
||
7.0
|
||
Repeater EIRP
|
||
dBW
|
||
+ 15.0
|
||
+15.0
|
||
(+17.3 for GOES-16)
|
||
Phase Jitter (in 50 Hz bandwidth)
|
||
deg. (rms)
|
||
10
|
||
|
||
Modulation Type
|
||
type
|
||
Linear Phase
|
||
None: frequency
|
||
translation
|
||
Transmitter
|
||
Nominal Modulation Index
|
||
Modulation Index Limit
|
||
radians
|
||
peak
|
||
1.0
|
||
2.0
|
||
N/A
|
||
Frequency Stability of downlink carrier
|
||
N/A
|
||
2.5 x 10-6
|
||
|
||
Amplitude Ripple (over any 24-hour
|
||
period)
|
||
dB
|
||
1
|
||
1
|
||
Linearity
|
||
dB
|
||
see note 1
|
||
30 dB below desired
|
||
signal levels
|
||
|
||
Note 1: Fixed Gain Mode - Two equal test tones each at 2 dB above the receiver noise
|
||
applied to the receiver input will not produce intermodulation products within the
|
||
transponder bandwidth greater than 20 dB below the test tone output level.
|
||
|
||
ALC Mode - Two equal test tones each at 7 dB above the receiver noise applied to
|
||
the receiver input will not produce intermodulation products within the transponder
|
||
bandwidth greater than 30 dB below the test tone output level.
|
||
|
||
3.5.3
|
||
GOES SAR Antennas
|
||
The relative gain pattern for the GOES SAR receive antenna is shown in Figure 3.9 for GOES
|
||
up to GOES-15 and in Figure 3.11 for GOES-16 and later. The antenna is right hand circular
|
||
polarized (RHCP) with an on-axis gain of 10 dB for GOES spacecraft up to GOES-15 and
|
||
about 14 dB for GOES-16.
|
||
|
||
|
||
|
||
|
||
3-11
|
||
|
||
|
||
|
||
For GOES spacecraft up to GOES-15, the receive line loss between the antenna terminal and
|
||
the low noise preamplifier is 1.9 dB. Therefore, the effective gain relative to the preamplifer
|
||
input is 8.1 dB. The receive antenna has a maximum axial ratio of 3 dB.
|
||
|
||
The relative gain pattern for the GOES through GOES-15 SAR transmit antenna is shown in
|
||
Figure 3.10. The antenna is RHCP with an on-axis gain of 12.3 dB. The transmit line loss
|
||
between the power amplifier and the antenna terminal is 1.7 dB. Therefore, the effective gain
|
||
relative to the power amplifier output is 10.6 dB. The transmit antenna has a maximum axial
|
||
ratio of 3 dB.
|
||
|
||
Figure 3-9: GOES Through GOES-15 Receive Antenna Pattern at 406.05 MHz
|
||
|
||
|
||
|
||
3-12
|
||
|
||
|
||
|
||
Figure 3-10: GOES Through GOES-15 Transmit Antenna Pattern at 1544.5 MHz
|
||
|
||
|
||
|
||
Figure 3-11: Typical GOES-16 and GOES-17 Receive Antenna Pattern at 406 MHz
|
||
|
||
|
||
|
||
|
||
3-13
|
||
|
||
|
||
|
||
Figure 3-12: Typical GOES-16 and 17 SAR Transmit antenna measured at 1544 MHz
|
||
|
||
For the GOES-16 and 17 transmit plot, Figure 3.12, the blue curve is the correct polarization
|
||
(RHCP) and the red curve is cross polarization (LHCP) plots.
|
||
|
||
|
||
|
||
- END OF SECTION 3 -
|
||
|
||
|
||
|
||
|
||
|
||
4-1
|
||
|
||
|
||
|
||
4.
|
||
INSAT/GSAT 406 MHZ GEOSAR REPEATER
|
||
4.1
|
||
INSAT/GSAT Repeater Functional Description
|
||
SAR instruments are included on the INSAT-3D, INSAT-3DR, GSAT-17 and INSAT-3DS
|
||
satellites. On each of these satellites the SAR payloads share some common circuitry with the
|
||
Data Relay Transponder (DRT) meteorological instruments. A functional diagram of the
|
||
INSAT/GSAT SAR payloads is provided at Figure 4.1.
|
||
|
||
Figure 4-1: INSAT/GSAT SAR / DRT Repeater Functional Block Diagram
|
||
|
||
406.05 MHz signals from Cospas-Sarsat distress beacon within the coverage area of the SAR
|
||
receive antenna are fed to a pre-select helical band pass filter which helps suppress out-of-band
|
||
interference. The filtered signal is passed to a low noise amplifier (LNA) to achieve the required
|
||
input noise figure. The signal is first down converted to 73.35 MHz, then passed through a crystal
|
||
bandpass filter. This signal is further down converted, such that an uplink signal at 406.05 MHz
|
||
would appear at 100 kHz. The resulting signal is passed to a transistorized limiter circuit and to a
|
||
low pass filter. The filtered signal is phase modulated and multiplied to achieve a modulation
|
||
index of ±1 radian at 71.0 MHz.
|
||
|
||
The main functions of the phase modulator are to:
|
||
• Reduce noise in the down link signal; and
|
||
• Provide a continuous down link carrier for LUT tracking receivers.
|
||
|
||
|
||
|
||
|
||
|
||
SAR Receiver
|
||
|
||
15WSSPA
|
||
Filter
|
||
|
||
|
||
|
||
0.9m Ext C BAND
|
||
DRT: 402.675
|
||
MHz
|
||
|
||
|
||
HYB
|
||
|
||
PSF
|
||
PSF
|
||
SHORTBACK FIRE 1m
|
||
ANTENNA
|
||
SAS&R:
|
||
406.05 MHz
|
||
|
||
DRT/SAS&R
|
||
Receiver
|
||
LHCP
|
||
|
||
|
||
RHCP
|
||
|
||
SW TR SW
|
||
|
||
DRT: 4503.385 MHz
|
||
SAS&R: 4504.2 MHz
|
||
|
||
|
||
|
||
4-2
|
||
|
||
|
||
|
||
The output signal form the modulator is filtered, combined with the DRT IF signal (70.05 MHz),
|
||
up-converted to 4504.2 MHz and applied to a 15-Watt solid state power amplifier (SSPA operating
|
||
at 3 dB out back off at 0 dB BOA settings). The composite DRT / SAR transponder signal is passed
|
||
to an extended C band multiplexer (MUX). Finally the signal is routed to an extended C band
|
||
antenna which provides an EIRP of 4 dBW for INSAT-3DS (minimum).
|
||
4.2
|
||
INSAT/GSAT Repeater Operating Modes
|
||
Each INSAT repeater has a redundant receiver and a redundant transmitter that can be selected to
|
||
define a complete repeater configuration. A specific repeater configuration can be operated in the
|
||
modes described in Table 4.1.
|
||
Table 4.1: INSAT/GSAT Repeater Operating Modes
|
||
|
||
Mode
|
||
Band Center
|
||
Frequency (MHz)
|
||
Receiver 1 dB
|
||
Bandwidth (kHz)
|
||
Wide Band
|
||
406.050
|
||
|
||
4.3
|
||
INSAT/GSAT Repeater Spectrum Characteristics
|
||
The spectral occupancy of the transmitted signal with the repeater in a wide band mode is shown
|
||
in Figure 4.2 and Figure 4.3. This output spectrum, therefore, represents the case of maximum
|
||
spectrum occupancy.
|
||
|
||
The received 406.05 MHz beacon signals are filtered and translated to a baseband frequency prior
|
||
to phase modulation in the transmitter. The wide band mode (80 kHz bandwidth) frequency plan
|
||
is such that a Cospas-Sarsat beacon signal received at 406.05 MHz becomes 100 kHz in the
|
||
baseband spectrum.
|
||
|
||
|
||
|
||
|
||
4-3
|
||
|
||
|
||
|
||
Figure 4-2: INSAT Transmitter Output Spectral Occupancy with No Test Signal
|
||
|
||
|
||
|
||
Figure 4-3: GSAT Transmitter Output Spectral Occupancy with No Test Signal
|
||
|
||
|
||
|
||
|
||
4-4
|
||
|
||
|
||
|
||
4.4
|
||
INSAT/GSAT Repeater Coverage Area
|
||
The zero-degree elevation angle coverage contours for the INSAT-3D, INSAT-3DR, GSAT-17
|
||
and INSA-3DS are shown in Figure 4.4, Figure 4.5, Figure 4.6 and Figure 4.7, respectively. The
|
||
receive antennas are broad beam earth coverage types. The downlink antennas are directive beams
|
||
that can be received in the Indian region.
|
||
|
||
|
||
Figure 4-4: INSAT-3D 0-Degree Elevation Angle
|
||
|
||
|
||
|
||
|
||
Figure 4-5: INSAT-3DR 0-Degree Elevation Angle
|
||
|
||
|
||
|
||
4-5
|
||
|
||
Figure 4-6: GSAT-17 0-Degree Elevation Angle
|
||
Figure 4-7: INSAT-3DS 0-Degree Elevation Angle
|
||
|
||
|
||
|
||
4-6
|
||
|
||
|
||
|
||
4.5
|
||
INSAT/GSAT Repeater Performance Parameters
|
||
|
||
The INSAT SAR repeater performance parameters for both INSAT-3D, INSAT-3DR, G-SAT-17
|
||
and INSAT-3DS are provided in Table 4.2.
|
||
|
||
Table 4.2: INSAT/GSAT Repeater Performance Parameters
|
||
|
||
Parameter
|
||
Unit
|
||
Specification
|
||
Receiver Band Pass Characteristics
|
||
|
||
Wide band mode center frequency
|
||
|
||
Wide band mode bandwidth
|
||
|
||
MHz
|
||
kHz
|
||
|
||
406.05
|
||
|
||
Antenna Type (UHF)
|
||
N/A
|
||
Short back fire (SBF)
|
||
Rx Antenna Polarization
|
||
N/A
|
||
RHCP
|
||
SBF Antenna Gain
|
||
dBi
|
||
|
||
UHF receive antenna axial ratio
|
||
dB
|
||
2.0
|
||
Receive coverage
|
||
N/A
|
||
Global
|
||
Receive Gain to Noise Temp Ratio (G/T)
|
||
dB/K
|
||
-19.0
|
||
Nominal Input Level
|
||
dBW
|
||
|
||
Dynamic Range
|
||
dB
|
||
|
||
Spurious outside the transmit band in any 4 kHz Band
|
||
dBW
|
||
< -60
|
||
Gain Stability (over operating life)
|
||
dB PP
|
||
4.0
|
||
Transmit Center frequency
|
||
MHz
|
||
INSAT-3D : 4507.0
|
||
INSAT-3DR : 4504.2
|
||
GSAT-17 : 4504.2
|
||
INSAT-3DS : 4504.2
|
||
Tx Antenna Polarization
|
||
N/A
|
||
Linear V
|
||
Transmit Antenna Input
|
||
dBm
|
||
7.5
|
||
Transmit Antenna Gain (EOC)
|
||
dB
|
||
26.5
|
||
EIRP (EOC at end of life)
|
||
dBW
|
||
|
||
Tx Antenna Beam Coverage
|
||
N/A
|
||
INDIA Mainland
|
||
SAR Signal Modulation
|
||
N/A
|
||
Phase modulation
|
||
Modulation Index (Nominal)
|
||
Radian
|
||
1.0 ± 0.2
|
||
Overall Frequency translation error (Over lifetime)
|
||
PPM
|
||
± 8.0
|
||
4.6
|
||
INSAT/GSAT SAR Antennas
|
||
The SAR receive antenna (SBF type) for INSAT/GSAT satellites provide global coverage. The
|
||
antenna is right hand circular polarized (RHCP) with an edge of coverage (EOC) gain of 12.2 dB.
|
||
The pattern for INSAT-3D is shown in Figure 4.8, for INSAT-3DR in Figure 4.9, for GSAT-17 in
|
||
Figure 4.10 and for INSAT-3DS in Figure 4.11. The receive antenna has a maximum axial ratio
|
||
of 2 dB.
|
||
|
||
|
||
|
||
|
||
4-7
|
||
|
||
|
||
|
||
Figure 4-8: INSAT-3D SASR 406.05 MHz Receive Antenna Contour Pattern
|
||
|
||
|
||
Figure 4-9: INSAT-3DR SASR 406.05 MHz Receive Antenna Contour Pattern
|
||
|
||
|
||
4-8
|
||
|
||
Figure 4-10: GSAT-17 SAR 406.05 MHz Receive Antenna Contour Pattern
|
||
Figure 4-11: INSAT-3DS SASR 406.05 MHz Receive Antenna Contour Pattern
|
||
|
||
|
||
4-9
|
||
|
||
The INSAT/GSAT extended C-band transmit antenna is a directive antenna that provides coverage
|
||
for the Indian region. The pattern is shown in Figure 4.12 for INSAT-3D, in Figure 4.13 for
|
||
INSAT 3-DR, in Figure 4.14 for GSAT-17 and in Figure 4.15 for INSAT-3DS. The antenna is
|
||
vertically polarized with an EOC gain of 26.0 dB.
|
||
Figure 4-12: INSAT-3D Transmit Antenna Contour Pattern
|
||
Figure 4-13: INSAT-3DR Transmit Antenna Contour Pattern
|
||
|
||
|
||
|
||
4-10
|
||
|
||
|
||
|
||
Figure 4-14: GSAT-17 Transmit Antenna Contour Pattern
|
||
|
||
|
||
Figure 4-15: INSAT-3DS Transmit Antenna Contour Pattern
|
||
|
||
|
||
|
||
– END OF SECTION 4 –
|
||
|
||
|
||
|
||
5-1
|
||
|
||
|
||
|
||
5.
|
||
ELECTRO-L GEOSAR REPEATER
|
||
5.1
|
||
Repeater Functional Diagram Description
|
||
A functional diagram of the Electro-L SAR repeater is shown in Figure 5.1 and Figure 5.2. The
|
||
repeater is redundantly configured and consists of the following units:
|
||
• two 406 MHz low-noise amplifiers (shared with another satellite subsystem);
|
||
• two dual conversion 406 MHz receivers (down converter, up converter);
|
||
• two 4-Watt 1.5 GHz transmitters;
|
||
• one 406 MHz receive antenna; and
|
||
• one 1544.5 MHz transmit antenna.
|
||
There are two generations of Electro-L SAR repeaters: with linear phase modulation (Electro-L
|
||
No. 1, 2 and 3) and frequency translation (“bent-pipe”) transponder (Electro-L No. 4 and onwards).
|
||
|
||
5.1.1 ELECTRO-L Linear Phase Modulation Repeaters (Electro- L No. 1, 2 and 3)
|
||
406 MHz signals from 406 MHz beacons are received by the antenna and fed through the diplexer
|
||
and switch to a low-noise amplifier. The low-noise amplifier output is connected to the SAR
|
||
receiver. The signal is down-converted for bandpass filtering in accordance with one of two
|
||
commandable band with modes; a narrow band mode of 20 kHz or a wide band mode of 80 kHz.
|
||
|
||
The filtered output signal is further down-converted to the near baseband and fed through
|
||
amplifiers to the SAR transmitter. The overall gain of the SAR receiver is selected into a fixed
|
||
gain mode only.
|
||
|
||
The SAR transmitter linear phase modulates the signal 1544.5 MHz and amplifies the modulated
|
||
carrier to 4 Watts. The phase-modulated signal has the nominal modulation index set to 0.7 radian
|
||
(rms). A baseband limiter restricts the modulation index from exceeding 2 radians. The
|
||
transmitter output is applied through a 4 MHz bandwidth filter to antenna.
|
||
|
||
5.1.2 ELECTRO-L Frequency Translation Repeaters (Electro-L No.4 and
|
||
Onwards)
|
||
The SAR repeater is based on frequency translation type transponder with no frequency inversion.
|
||
The 406 MHz signals from beacons are received by the antenna and fed through the diplexer and
|
||
switch to a low-noise amplifier. The low-noise amplifier output is connected to the SAR receiver.
|
||
The signal is down-converted for bandpass filtering with only wide band mode of 80 kHz. Repeater
|
||
gain is self-regulated by Automatic Gain control (AGC). The repeater gain is automatically
|
||
adjusted to obtain a power of 4 W at the output of the SAR transponder.
|
||
|
||
|
||
|
||
5-2
|
||
|
||
|
||
|
||
5.2
|
||
Electro-L Repeater Operating Modes
|
||
A specific repeater configuration can be operated in the modes described in Table 5.1.
|
||
|
||
Table 5.1: Electro-L Repeater Operating Modes
|
||
|
||
Mode
|
||
Band Center Frequency
|
||
(MHz)
|
||
Receiver 3 dB Bandwidth
|
||
(kHz)
|
||
ELECTRO-L (No.1, No.2, No.3)
|
||
Narrow Band with Fixed Gain
|
||
406.025
|
||
|
||
Wide Band with Fixed Gain
|
||
406.050
|
||
|
||
ELECTRO-L (No.4 and onwards)
|
||
|
||
|
||
|
||
Wide Band with Automatic Gain Control
|
||
406.050
|
||
|
||
1544.5 MHz
|
||
406 MHz
|
||
LEGEND
|
||
FS1...FS3 - frequency synthesizers;
|
||
S - switch of the quartz filters;
|
||
QF - quartz filter;
|
||
LPM - linear phase modulator;
|
||
ATT - attenuator;
|
||
PSS1...PSS2 - power supply sources
|
||
Ant1 - directive antenna of the receiving channel;
|
||
Ant2 - directive antenna of the transmission channel;
|
||
LNA - low-noise amplifier;
|
||
A - amplifier;
|
||
F1...F4 - frequency filters;
|
||
M1, M2 - frequency mixers
|
||
LNA
|
||
A
|
||
F2
|
||
M1
|
||
FS1
|
||
A
|
||
Down converter
|
||
Input unit
|
||
F=(406.05±0.05) MHz
|
||
Fо=10 MHz
|
||
Fg=380 MHz
|
||
F=26.05 MHz
|
||
Power
|
||
amplifier
|
||
PSS3
|
||
PSS1
|
||
F4
|
||
F1
|
||
Ant1
|
||
Ant2
|
||
A
|
||
S
|
||
QF
|
||
20kHz
|
||
QF
|
||
80кHz
|
||
M2
|
||
FS2
|
||
A
|
||
A
|
||
LPM
|
||
A
|
||
F3
|
||
ATT
|
||
FS3
|
||
Up converter and LFM
|
||
Fo=10 MHz
|
||
Fo=10 MHz
|
||
PSS2
|
||
A
|
||
Fg=26 MHz
|
||
Fg=1544.5 MHz
|
||
0.05 MHz
|
||
|
||
Figure 5-1: Electro-L SAR Functional Diagram (Linear Phase Modulation Repeater)
|
||
|
||
|
||
|
||
|
||
|
||
5-3
|
||
|
||
|
||
|
||
LEGEND
|
||
|
||
|
||
Ant1 - directive antenna of the receiving channel;
|
||
Ant2 - directive antenna of the transmission channel;
|
||
LNA - low-noise amplifier;
|
||
A - amplifier;
|
||
F1...F4 - frequency filters; M1, M2 - frequency mixers
|
||
FS1,FS2 - frequency synthesizers;
|
||
QF - quartz filter;
|
||
ATT - attenuator;
|
||
PSS1...PSS3 - power supply sources
|
||
|
||
Figure 5-2: Electro-L SAR Functional Diagram (Frequency Translation Repeater)
|
||
|
||
5.3
|
||
Electro-L Repeater Baseband Spectrum
|
||
5.3.1 ELECTRO-L Linear Phase Modulation Repeaters (Electro- L No. 1, 2
|
||
and 3)
|
||
|
||
The received 406 MHz signals are filtered and translated to a baseband frequency prior to phase
|
||
modulation in the transmitter. The modulation plan is such that a beacon received at the
|
||
406.025 MHz will be at 25 kHz in baseband spectrum. The 20 kHz and 80 kHz filters control the
|
||
baseband spectrum width.
|
||
|
||
The Electro-L SAR downlink spectrum occupancies in WB and NB modes are depicted in
|
||
Figures 5.3 and 5.4 respectively. Note that out-of-band emissions are not greater than 30 dB below
|
||
the carrier frequency level.
|
||
|
||
|
||
|
||
5-4
|
||
|
||
|
||
|
||
Figure 5-3: Spectrum Occupancy of Downlink Signal in WB Mode
|
||
Spanned 300 kHz Around 1544.5 MHz
|
||
|
||
|
||
Figure 5-4: Spectrum Occupancy of Downlink Signal in NB Mode
|
||
Spanned 1 MHz Around 1544.5 MHz
|
||
|
||
|
||
5.3.2 ELECTRO-L Frequency Translation Repeaters (Electro-L No.4 and
|
||
Onwards)
|
||
The Electro-L SAR frequency translation repeater can operate in one gain and one bandwidth
|
||
mode. The nominal SAR downlink spectrum occupancy is depicted in Figure 5.5.
|
||
|
||
|
||
|
||
5-5
|
||
|
||
Figure 5-5: Spectrum Occupancy of Downlink Signal Centred at 1544.5 MHz.
|
||
Electro-L No.4
|
||
5.4
|
||
Electro-L Repeater Coverage Area
|
||
The 0-degree elevation angle coverage contour for the Electro-L satellite are provided in
|
||
Figure 5.6. The receive and transmit antennas are broad beam earth coverage types. Therefore,
|
||
the coverage patterns in Figure 5.6 apply to both receive and transmit functions.
|
||
Figure 5-6: Electro-L 0o Elevation Angle Footprint
|
||
(Electro- L No 2, 3 and 4)
|
||
|
||
|
||
|
||
5-6
|
||
|
||
|
||
|
||
5.5
|
||
Electro-L Repeater Performance Parameters
|
||
5.5.1
|
||
Electro-L SAR Receiver Parameters
|
||
The receiver parameters are shown in Table 5.2.
|
||
|
||
Table 5.2: Electro-L SAR Receiver Parameters
|
||
|
||
No.
|
||
Parameter
|
||
Unit
|
||
Values
|
||
1.
|
||
Nominal input level at Antenna
|
||
dBW
|
||
|
||
2.
|
||
System Noise Temperature (referred to LNA)
|
||
K
|
||
|
||
3.
|
||
G/Т
|
||
dB/K
|
||
-16.5 (see Note)
|
||
4.
|
||
Receiver Bandpass Characteristic
|
||
Linear phase modulation repeater:
|
||
Narrow Band Mode (relat. to 406.025)
|
||
|
||
|
||
Wide Band Mode (relat. to 406.050)
|
||
|
||
|
||
Bent-pipe repeater:
|
||
Wide Band Mode (relat. to 406.050)
|
||
|
||
For more information see Figures 5.7, 5.8 and 5.9.
|
||
|
||
|
||
kHz
|
||
|
||
|
||
kHz
|
||
|
||
|
||
kHz
|
||
|
||
|
||
33 (-1 dB)
|
||
39 (-3 dB)
|
||
64 (-20 dB)
|
||
78 (-1 dB)
|
||
138 (-3 dB)
|
||
|
||
96 (-3 dB)
|
||
120 (-10 dB)
|
||
5.
|
||
Dynamic Range
|
||
kHz dB
|
||
≤ 15
|
||
6.
|
||
Group Delay (over 4 kHz)
|
||
s
|
||
≤ 13
|
||
7.
|
||
Image Rejection
|
||
dB
|
||
|
||
8.
|
||
Frequency Stability for 24h/10 years
|
||
dB
|
||
± 2.5 x 10-6
|
||
Note: For Electro-L No. 2 the G/T value was measured at -21.9 dB/K.
|
||
|
||
|
||
|
||
5-7
|
||
|
||
|
||
|
||
Figure 5-7: Electro-L SAR Receiver Bandpass Filter Amplitude-Frequency Response
|
||
(Linear Phase Modulation Repeater NB Mode)
|
||
|
||
|
||
|
||
Figure 5-8: Electro-L SAR Receiver Bandpass Filter Amplitude-Frequency Response
|
||
(Linear Phase Modulation Repeater WB Mode)
|
||
|
||
|
||
|
||
|
||
5-8
|
||
|
||
|
||
|
||
Figure 5-9: Electro-L SAR Receiver Bandpass Filter Amplitude-Frequency Response
|
||
(Frequency Translation Repeater)
|
||
|
||
5.5.2
|
||
Electro-L SAR Transmitter Parameters
|
||
The transmitter parameters are shown in Table 5.3.
|
||
|
||
Table 5.3: Electro-L SAR Transmitter Parameters
|
||
|
||
No.
|
||
Parameter
|
||
Unit
|
||
Values
|
||
|
||
No. 1,2 and 3
|
||
No. 4 and
|
||
onwards
|
||
No. Centre Frequency
|
||
МHz
|
||
1544.5
|
||
|
||
2.
|
||
Output Power of Transmitter
|
||
dBW
|
||
6.0
|
||
|
||
3.
|
||
Repeater EIRP
|
||
dBW
|
||
20.1
|
||
|
||
4.
|
||
Phase Jitter (in 50 Hz bandwidth)
|
||
deg
|
||
≤ 10 (r.m.s.)
|
||
≤ 10 (r.m.s.)
|
||
5.
|
||
Modulation Type
|
||
|
||
Linear Phase
|
||
-
|
||
6.
|
||
Nominal Modulation Index
|
||
radian
|
||
0.7 (rms)
|
||
-
|
||
7.
|
||
Modulation Index Limit
|
||
radian
|
||
2.0
|
||
-
|
||
8.
|
||
Frequency Stability
|
||
|
||
±2.5 x 10-7
|
||
9.
|
||
Amplitude Ripple (over any 24 hour)
|
||
dB
|
||
±1
|
||
±1.7
|
||
10.
|
||
Linearity
|
||
|
||
See Note 1
|
||
|
||
|
||
Note 1:
|
||
Fixed gain mode: Two equal test tones each at 2 dB above the receiver noise applied to the
|
||
receive input will not produce intermodulation products within the transponder bandwidth
|
||
greater than 20 dB below the test tone output level.
|
||
|
||
|
||
|
||
5-9
|
||
|
||
|
||
|
||
AGC Mode: Two equal test tones each at 7 dB above the receiver noise applied to the receiver
|
||
input will not produce intermodulation products within the transponder bandwidth greater
|
||
than 18 dB below the test tone output level.
|
||
|
||
5.5.3
|
||
Electro-L SAR Antennas
|
||
The SAR receive antenna is right-hand circularly polarized (RHCP) with an on-axis gain of
|
||
15 dB including line loss. The receive antenna has a maximum axial ratio of 3 dB.
|
||
|
||
The SAR transmit antenna is also LHCP with an on-axis gain of 12 dB (±9o beamwidth)
|
||
including line loss. The transmit antenna has a maximum axial ratio of 3 dB.
|
||
|
||
|
||
|
||
– END OF SECTION 5 –
|
||
|
||
|
||
|
||
6-1
|
||
|
||
6.
|
||
MSG 406 MHZ GEOSAR REPEATER
|
||
6.1
|
||
MSG Repeater Functional Description
|
||
A functional block diagram of the overall MSG telecommunications payload, including the SAR
|
||
transponder is shown in Figure 6.1. The SAR transponder comprises the following:
|
||
A UHF receive antenna which is made up of an array of 16 crossed dipoles located close
|
||
to the periphery of the main satellite drum. The dipoles of this array are electronically
|
||
switched in order to form an electronically de-spun antenna beam that fully covers the
|
||
Earth.
|
||
An input filter.
|
||
A redundant UHF receiver which provides low-noise amplification for the SAR channel.
|
||
A non-redundant SAR transponder which provides channel filtering, amplification, and up-
|
||
conversion for the SAR channel. The SAR channel has fixed gain and bandwidth.
|
||
A wave-guide output multiplexer (OMUX) in which the SAR signals are multiplexed with
|
||
the other L-band downlink signals.
|
||
An L-band transmit antenna comprising an array of dipoles arranged in 32 columns each
|
||
with 4 dipoles connected in parallel. The columns of this array are also electronically
|
||
switched to make a de-spun antenna beam that fully covers the Earth.
|
||
Figure 6-1: MSG Search and Rescue Repeater Functional Diagram
|
||
|
||
|
||
6-2
|
||
|
||
6.2
|
||
MSG Repeater Operating Modes
|
||
The only operating modes of the MSG SAR payload are SAR transponder off and on. The mode
|
||
switching operations must be performed by EUMETSAT.
|
||
6.3
|
||
MSG Repeater Spectrum Characteristics
|
||
The spectral occupancy of the transmitted signal is shown in Figure 6.2.
|
||
Figure 6-2: MSG L-Band Transmitter Output Spectral Occupancy
|
||
The received beacon signals in the nominal 60 kHz uplink band from 406.020 MHz to
|
||
406.080 MHz, are directly translated to the L-band downlink centred at 1,544.5 MHz. The signal
|
||
is not converted to baseband or a low intermediate frequency at any point. Signals at 406.05 MHz
|
||
are converted to 1,544.5 MHz. The frequency stability is ±6 ppm and ±9 ppm at beginning and
|
||
|
||
|
||
|
||
6-3
|
||
|
||
|
||
|
||
end of satellite life respectively. The main filtering of the band is performed in the SAR
|
||
transponder block using a SAW filter operating in the uplink frequency band.
|
||
|
||
The specified useful channel bandwidth is > 60 kHz. The measurements (see Figure 6.3) indicate
|
||
that a 0.5 dB-channel bandwidth of approximately 100 kHz is achieved. The measured
|
||
noise-equivalent bandwidth is in the order of 180 kHz.
|
||
|
||
|
||
Figure 6-3: Measured Pass-Band of MSG Transponder
|
||
|
||
Although a single figure cannot be used to describe short term frequency conversion stability
|
||
characteristics of the MSG GEOSAR payload, the phase noise table (Table 6.1) and phase noise
|
||
spectrum (Figure 6.4) of the transmitter local oscillator (LO) as measured for the first MSG flight
|
||
model provide an indication of anticipated MSG performance.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
6-4
|
||
|
||
|
||
|
||
Table 6.1: MSG Transmitter LO Phase Noise
|
||
|
||
Random Spurious Modulation
|
||
Frequency
|
||
Measured FM-1 [dBc/Hz]
|
||
fo + 10Hz
|
||
|
||
fo + 100Hz
|
||
|
||
fo + 1KHz
|
||
|
||
fo + 10KHz
|
||
|
||
fo + 100KHz
|
||
|
||
Figure 6-4: MSG Transmitter LO Phase Noise Spectrum Plot
|
||
|
||
|
||
|
||
|
||
|
||
|
||
6-5
|
||
|
||
|
||
|
||
6.3
|
||
MSG Repeater Coverage Area
|
||
|
||
Both the UHF receive antenna and the L-band transmit antenna provide coverage of the full
|
||
Earth as seen from longitude 0.0°. Both antenna boresights are slightly tilted to the North.
|
||
The design of the SAR transponder has been based upon the following minimum satellite
|
||
elevation angles:
|
||
• from the emergency beacons: 5 degrees,
|
||
• from the receive ground stations (GEOLUTs): 18 degrees.
|
||
|
||
The geographical coverage area is indicated in Figure 6.5.
|
||
|
||
|
||
|
||
Figure 6-5: MSG 5 o Elevation Angle Coverage Contour
|
||
|
||
6.4
|
||
MSG Repeater Performance Parameters
|
||
|
||
The principal worst case MSG repeater performance parameters as measured on the first flight
|
||
model are shown in Table 6.2.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
6-6
|
||
|
||
|
||
|
||
Table 6.2: MSG SAR Repeater Performance Parameters
|
||
|
||
Parameter
|
||
Unit
|
||
Values
|
||
Uplink Centre Frequency
|
||
MHz
|
||
406.050
|
||
Nominal Input Level at Antenna*
|
||
dBW
|
||
-176.9
|
||
System Noise Temperature
|
||
K
|
||
|
||
Receive Antenna G/T
|
||
dB/K
|
||
-21.3
|
||
Bandpass Characteristic
|
||
Specified Band
|
||
Measured 0.5 dB-Band
|
||
Noise-Equivalent Band (approx.)
|
||
|
||
kHz
|
||
|
||
>60.0
|
||
100.0
|
||
180.0
|
||
Dynamic Range†
|
||
dB
|
||
n/a
|
||
Phase Linearity (overall in band, specified)
|
||
deg
|
||
4.0
|
||
AM/PM Conversion
|
||
°/dB
|
||
0.9
|
||
Image Rejection
|
||
dB
|
||
>80.0
|
||
AGC Time Constant‡
|
||
|
||
No AGC
|
||
Transponder Gain
|
||
dB
|
||
148§
|
||
Transponder Linearity (C/I)
|
||
dB
|
||
20.0
|
||
Gain Stability (over Temperature, Frequency & Lifetime)
|
||
dB pk-pk
|
||
2.0
|
||
Output Frequency Stability
|
||
ppm
|
||
± 9
|
||
Downlink Centre Frequency
|
||
MHz
|
||
1,544.5
|
||
Downlink Polarisation
|
||
|
||
Lin. Horiz.
|
||
Maximum Output Power of Transmitter
|
||
dBW
|
||
0.0
|
||
Repeater EIRP per Useful Carrier**
|
||
dBW
|
||
-19.0
|
||
Modulation Type
|
||
|
||
As uplink
|
||
Transmitter Nominal Modulation Index
|
||
|
||
As uplink
|
||
6.5
|
||
MSG SAR Antennas
|
||
The MSG satellite spins at a rate of 100 rpm ± 1%. To provide continuous coverage of a portion
|
||
of the earth’s surface, the MSG SAR instrument utilises electronically switched de-spun antennas.
|
||
The electronic switching has a cyclical impact on the performance of the transmit and receive
|
||
antennas as described below.
|
||
|
||
|
||
|
||
|
||
|
||
* Nominal input level at antenna from a 5 Watt Cospas-Sarsat beacon located at 5° elevation angle to the satellite.
|
||
Includes 6.8 dB polarisation loss.
|
||
† This is a transparent transponder. It is driven by noise so that dynamic range is less relevant.
|
||
‡ The SAR transponder operates only in fixed-gain mode.
|
||
§ Signal gain is sensitive to the composite power loading of the transponder (which is dominated by noise). Strong
|
||
ground interference may cause a reduction of gain. Link margin can be provided by adequate receiving ground
|
||
station G/T selection.
|
||
** Assumes two beacons operating at nominal levels and 3 interfering carriers transmitted from ground with EIRP 3 dB
|
||
higher than the beacon signals and randomly distributed within 60 kHz operational bandwidth.
|
||
|
||
|
||
|
||
6-7
|
||
|
||
|
||
|
||
6.5.1
|
||
MSG SAR Receive Antenna
|
||
|
||
The MSG SAR instrument uses an electronically switched de-spun (ESDA) right hand
|
||
circularly polarised receive antenna, with gain performance as depicted at Figure 6.6. The
|
||
values provided in this figure represent the minimum dynamic gain over the coverage area,
|
||
and with the satellite spin, the gain fluctuates above this value at a rate of 26.7 Hz. The
|
||
measured fluctuation (gain ripple) is 1.3 dB peak to peak in the south and up to 1.8 dB peak
|
||
to peak in the north.
|
||
|
||
The minimum gain (co-polar component) in the coverage area ranges from 3.1 dBi to 4.5 dBi,
|
||
while during the scan the gain can be as high as 5.6 dBi. The cross-polar component (XPD)
|
||
varies in the coverage and ranges from -9.0 dB to 14.2 dB.
|
||
|
||
Both the gain and the polarisation loss are directly involved in the uplink quality, the worst
|
||
case combination of the two effects has been estimated: min[(Gain Polarisation Loss)]. This
|
||
occurs at a point in the west of the coverage where G = 3.45 dBi and XPD = 9 dB
|
||
(i.e., polarisation loss = -6.78 dB). Since this represents the worst case situation, these values
|
||
should be used when designing GEOLUTs which will operate with the MSG satellite.
|
||
|
||
6.5.2
|
||
MSG SAR Transmit Antenna
|
||
|
||
The MSG SAR instrument uses an electronically switched de-spun (ESDA) horizontally
|
||
polarised transmit antenna, with typical gain performance as depicted at Figure 6.7. The
|
||
values provided in this figure represent the minimum dynamic gain over the coverage area,
|
||
and with the satellite spin, the gain fluctuates above this value at a rate of 53.3 Hz. The
|
||
measured fluctuation (gain ripple) is typically 0.8 dB and will not exceed 1.6 dB peak to peak
|
||
from column to column.
|
||
|
||
|
||
|
||
|
||
6-8
|
||
|
||
|
||
|
||
Figure 6-6: MSG SAR Receive Antenna Pattern
|
||
|
||
|
||
|
||
6-9
|
||
|
||
|
||
|
||
Figure 6-7: MSG SAR Transmit Antenna Pattern
|
||
|
||
Note: The figures depicted above depict the antenna gain at 1,544.5 MHz.
|
||
|
||
|
||
|
||
- END OF SECTION 6 -
|
||
|
||
|
||
|
||
7-1
|
||
|
||
|
||
|
||
7.
|
||
LOUCH-5A GEOSAR REPEATER
|
||
7.1
|
||
Louch-5A Repeater Functional Description
|
||
A functional block diagram of the combined SAR and environmental data dissemination network
|
||
(EDDN) channels transponder is shown in Figure 7.1. The transponder comprises the following:
|
||
|
||
a.
|
||
Low noise amplifier that enables minimal effective noise temperature of the transponder
|
||
|
||
b.
|
||
SAR channel filter with 80 kHz pass band (at -3 dB)
|
||
|
||
c.
|
||
Down-converter that translates the input signal down to a first IF band (41.375±0.5 MHz)
|
||
|
||
d.
|
||
Amplifier (gain not less than minus 10 dB)
|
||
|
||
|
||
|
||
Figure 7-1: Louch-5A Combined SAR and EDDN Transponder
|
||
|
||
7.2
|
||
Louch-5A Repeater Operating Modes
|
||
The only operating modes of the Louch-5A SAR payload are SAR transponder on and off with
|
||
gain setting variation.
|
||
7.3
|
||
Louch-5A Spectrum Characteristics
|
||
The spectral occupancy of the transmitted signal is shown in Figure 7.2.
|
||
|
||
|
||
LNA
|
||
Filter
|
||
Down.
|
||
Conv. 1
|
||
Down.
|
||
Conv.2
|
||
OSC
|
||
Amp
|
||
EDDN
|
||
SAR
|
||
EDDN
|
||
EDDN
|
||
SAR
|
||
SAR
|
||
From receive
|
||
antenna
|
||
To transmit
|
||
antenna
|
||
|
||
|
||
7-2
|
||
|
||
Figure 7-2: Louch-5A Transmitter Spectrum Occupancy
|
||
7.4
|
||
Louch-5A Coverage Area
|
||
The 0-, 5- and 10-degree elevation angle coverage contours for the Louch-5A is shown in
|
||
Figure 7.3. The zones are determined with the following orbit parameters:
|
||
•
|
||
Sidereal period = 86164 ± 1 sec
|
||
•
|
||
Eccentricity = 0.0 - 0.0006
|
||
•
|
||
Inclination = 0˚ - 5˚
|
||
7.5
|
||
Louch-5A Repeater Performance Characteristics
|
||
The principal Louch-5A repeater performance parameters are shown in Tables 7.1. and 7.2 for
|
||
SAR receiver and SAR transmitter respectively.
|
||
Louch-5A combined SAR and EDDN channels transponder has fixed gain factor over the range
|
||
between LNA input and power amplifier output. The value of the gain factor can be command set
|
||
and by default is 138 dB.
|
||
|
||
|
||
|
||
7-3
|
||
|
||
|
||
|
||
Figure 7-3: Louch-5A Coverage Zones for 0, 5 and 10 Degrees of Elevation Angle
|
||
|
||
|
||
Table 7.1: Louch-5A SAR Receiver Parameters
|
||
|
||
No.
|
||
Parameter
|
||
Unit
|
||
Values
|
||
1.
|
||
Operational bandwidth
|
||
Mhz
|
||
406.01-406.09
|
||
2.
|
||
Signal nominal level at LNA input
|
||
dBW
|
||
|
||
3.
|
||
G/Т (at the edge of service zone)
|
||
dB/K
|
||
-10.2
|
||
4.
|
||
Receiver Bandpass Characteristics:
|
||
kHz
|
||
±40 (at -3dB)
|
||
5.
|
||
Dynamic Range (for SAR channel relative to
|
||
nominal level -159 dBW)
|
||
dB
|
||
±10
|
||
6.
|
||
Image Rejection
|
||
dB
|
||
not less than 50
|
||
7.
|
||
Frequency Stability for:
|
||
24 hours:
|
||
100000 hours
|
||
|
||
|
||
±1*10-8
|
||
±1*10-7
|
||
|
||
|
||
|
||
|
||
|
||
|
||
7-4
|
||
|
||
|
||
|
||
Table 7.2: Louch-5A SAR Transmitter Parameters
|
||
|
||
No.
|
||
Parameter
|
||
Unit
|
||
Values
|
||
1.
|
||
Transmitter frequency range
|
||
MHz
|
||
1544.458-1544.542
|
||
2.
|
||
Output Power of Transmitter*
|
||
dBW
|
||
-10.2
|
||
3.
|
||
Repeater EIRP
|
||
dBW
|
||
7.1
|
||
4.
|
||
Phase Jitter (in 50 Hz bandwidth)
|
||
deg
|
||
0.6
|
||
5.
|
||
Modulation Type
|
||
Radian
|
||
n/a
|
||
6.
|
||
Frequency Stability for:
|
||
24 hours:
|
||
100000 hours:
|
||
МHz
|
||
|
||
±1*10-8
|
||
±2*10-7
|
||
7.
|
||
Amplitude Ripple
|
||
dB
|
||
less than 1.0
|
||
8.
|
||
Linearity
|
||
dB
|
||
|
||
7.6
|
||
Louch-5A SAR Antennas
|
||
|
||
The reception of the SAR signal is provided by four spiral P-band phased array antenna. The transmit
|
||
antenna is a four spiral L-band phased array antenna. Both antennas have global beam (17˚x17˚
|
||
beamwidth).
|
||
|
||
The receive antenna is a right hand circular polarized (RHCP) with an on-axis gain of 18.3 dB (16.2 on
|
||
the edge of the coverage) and axial ratio of 0.7. The receive line loss between the antenna terminal
|
||
and the low noise preamplifier is 0.6 dB.
|
||
|
||
The transmit antenna is a right hand circular polarized (RHCP) with an on-axis gain of 19.9 dB
|
||
(17.1 on the edge of the coverage) and axial ratio of 0.9. The transmit line loss between the antenna
|
||
terminal and the low noise preamplifier is 1 dB.
|
||
|
||
The receive and transmit antenna patterns are shown in Figures 7.4 and 7.5 respectively.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
* Since the power amplifier installed in the transponder is shared between SAR and EDDN channels the maximum
|
||
SAR channel output power is not greater than 100 mW (in linear mode)
|
||
|
||
|
||
|
||
7-5
|
||
|
||
|
||
|
||
Figure 7-4: Louch-5A Receive Antenna Pattern at 406.05 MHz
|
||
|
||
|
||
|
||
Figure 7-5: Louch-5A Transmit Antenna Pattern at 1544.5 MHz
|
||
|
||
|
||
|
||
- END OF SECTION 7 -
|
||
|
||
|
||
|
||
|
||
8-1
|
||
|
||
|
||
|
||
8.
|
||
MTG 406 MHZ GEOSAR REPEATER
|
||
8.1
|
||
MTG Repeater Functional Description
|
||
The MTG SAR repeater main elements are shown in the functional block diagram.
|
||
|
||
a)
|
||
A UHF-band receive antenna based on direct radiating array architecture.
|
||
b)
|
||
An input cover filter.
|
||
c)
|
||
A redundant UHF front end which provides low noise amplification.
|
||
d)
|
||
A non-redundant section including OCXO, frequency down/up conversion, channel
|
||
filtering and amplification up to 5 W.
|
||
e)
|
||
An output cavity filter.
|
||
f)
|
||
An L-band transmit antenna based on direct radiating array architecture.
|
||
|
||
|
||
Figure 8-1: MTG SAR Repeater Functional Block Diagram
|
||
8.2
|
||
MTG Repeater Operating Modes
|
||
The MTG SAR repeater can operate in two selectable bandwidth modes, narrowband (50 kHz)
|
||
and wideband (90 kHz). It has a fixed gain control with 30 dB range, adjustable by telecommand,
|
||
with nominal steps of 1 dB.
|
||
|
||
There are two selectable translation frequencies which are the same for narrowband and wideband
|
||
modes, resulting in the following downlink center frequencies:
|
||
• 1544.3 MHz and 1544.5 MHz for the wideband mode,
|
||
• 1544.293 MHz and 1544.493 MHz for the narrowband mode.
|
||
|
||
|
||
|
||
8-2
|
||
|
||
|
||
|
||
8.3
|
||
MTG Repeater Spectrum Characteristics
|
||
The MTG SAR transmit spectrum is shaped by the selectable IF crystal filters which define the
|
||
pass band. Figures 8.2 and 8.3 show a typical spectrum at L-band output for narrowband and
|
||
wideband modes.
|
||
|
||
|
||
Figure 8-2: MTG Repeater Output Spectrum (Narrowband Mode)
|
||
|
||
|
||
|
||
Figure 8-3: MTG Repeater Output Spectrum (Wideband Mode)
|
||
|
||
|
||
|
||
|
||
|
||
8-3
|
||
|
||
|
||
|
||
The bandpass characteristics of the MTG SAR repeater are shown in Figures 8-4 and 8-5 for
|
||
narrowband and wideband modes.
|
||
|
||
|
||
Figure 8-4: MTG SAR Repeater Narrowband Filter Performance
|
||
|
||
|
||
|
||
Figure 8-5: MTG SAR Repeater Wideband Filter Performance
|
||
|
||
|
||
|
||
|
||
8-4
|
||
|
||
|
||
|
||
8.4
|
||
MTG Repeater Coverage Area
|
||
The MTG SAR repeater is designed to cover the full visible Earth’s disc (elevation > 5°) both in
|
||
the UHF uplink and in the L-band downlink. The antenna patterns, including peak gain, are
|
||
included in section 8.5.
|
||
8.5
|
||
MTG Repeater Performance Parameters
|
||
Table 8.1: MTG SAR Repeater Performance Parameters
|
||
|
||
Parameter
|
||
Values
|
||
Unit
|
||
Receive centre frequency –wideband mode
|
||
406.050
|
||
MHz
|
||
Receive centre frequency –narrowband mode
|
||
406.043
|
||
MHz
|
||
Minimum input level at antenna
|
||
|
||
dBW
|
||
Receive antenna polarization
|
||
RHCP
|
||
|
||
Receive antenna axial ratio
|
||
< 3.2
|
||
dB
|
||
Receive antenna gain at end of coverage
|
||
|
||
dBi
|
||
Satellite G/T at edge of coverage
|
||
-15.5
|
||
dB/K
|
||
Transponder gain (w/o antennas)
|
||
134 - 163
|
||
dB
|
||
Transmit antenna gain at end of coverage
|
||
11.9
|
||
dBi
|
||
Transponder linearity
|
||
> 30
|
||
dBc
|
||
Short term frequency stability (100ms)
|
||
< 1.0 x -10
|
||
|
||
Group delay over 4 kHz
|
||
< 10
|
||
us/4kHz
|
||
Downlink frequency stability
|
||
Short term worst case
|
||
Long term worst case
|
||
|
||
± 0.27
|
||
± 1.5
|
||
|
||
ppm
|
||
ppm
|
||
Translation frequencies (selectable)
|
||
1138.45
|
||
1138.25
|
||
MHz
|
||
MHz
|
||
Downlink center frequencies
|
||
Wideband mode
|
||
Narrowband mode
|
||
|
||
1544.5 or 1544.3
|
||
1544.493 or 1544.293
|
||
|
||
MHz
|
||
MHz
|
||
Downlink max EIRP
|
||
Downlink nom EIRP*
|
||
> 15
|
||
2.5
|
||
dBW
|
||
dBW
|
||
Transmit antenna axial ratio
|
||
< 2.5
|
||
dB
|
||
Transmit antenna polarization
|
||
RHCP
|
||
|
||
|
||
* The nominal EIRP is computed with FGM step 9 and the assumed loading scenario is two beacons
|
||
operating at nominal levels (EIRP=37 dBm) and three additional beacons at EIRP 3 dB higher.
|
||
8.6
|
||
MTG SAR Antennas
|
||
The receive and transmit antennas make use of Direct Radiating Array (DRA) architecture.
|
||
Figures 8-6 and 8-7 show examples of the UHF and L-band co-polar gain patterns.
|
||
|
||
|
||
|
||
8-5
|
||
|
||
|
||
|
||
Figure 8-6: MTG UHF-Band Antenna Co-Polar Amplitude Pattern
|
||
(Antenna Gain in dB Relative to the Peak Gain of 14.2 dBi; Red Circle Shows the Earth)
|
||
|
||
|
||
Figure 8-7: MTG L-Band Antenna Co-Polar Amplitude Pattern
|
||
(Antenna Gain in dB Relative to the Peak Gain of 14.2 dBi; Red Circle Shows the Earth)
|
||
|
||
|
||
- END OF SECTION 8 –
|
||
|
||
|
||
- END OF DOCUMENT -
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
Cospas-Sarsat Secretariat
|
||
1250 René-Lévesque Blvd. West, Suite 4215, Montreal (Quebec) H3B 4W8 Canada
|
||
Telephone: +1 514 500 7999
|
||
Fax: +1 514 500 7996
|
||
Email: mail@cospas-sarsat.int
|
||
Website: http://www.cospas-sarsat.int |