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.
1115 lines
37 KiB
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1115 lines
37 KiB
Markdown
---
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title: "T022: Cospas-Sarsat System Beacon Specification And Design Guidelines C"
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description: "Official Cospas-Sarsat T-series document T022"
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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: "T022"
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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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documentDate: "October 2023"
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originalTitle: "Cospas-Sarsat System Beacon Specification"
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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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> **Date:** October 2023
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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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# T022 - T022-OCT-27-2023.pdf
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**Pages:** 21
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---
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COSPAS-SARSAT SYSTEM BEACON SPECIFICATION
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AND DESIGN GUIDELINES
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C/S T.022
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Issue 2, Revision 1
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COSPAS-SARSAT SYSTEM BEACON
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SPECIFICATION AND DESIGN GUIDELINES
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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 by the Cospas-Sarsat Council (CSC-59)
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Approved by the Cospas-Sarsat Council (CSC-62)
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Approved by the Cospas-Sarsat Council (CSC-64)
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Approved by the Cospas-Sarsat Council (CSC-66)
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Approved by the Cospas-Sarsat Council (CSC-69)
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TABLE OF CONTENTS
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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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Scope
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1-1
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1.3
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Reference Documents................................................................................................. 1-1
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2.
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PERFORMANCE SPECIFICATION AND DESIGN GUIDELINES FOR
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REFERENCE BEACONS ................................................................................................. 2-1
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2.1
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Purpose 2-1
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2.2
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Requirements Common to all Reference Beacons ..................................................... 2-1
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2.3
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Requirements for Designated QMS Reference Beacons ............................................ 2-2
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2.3.1
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Designated LEOSAR QMS Reference Beacons............................................ 2-2
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2.3.2
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Designated GEOSAR QMS Reference Beacons ........................................... 2-2
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2.3.3
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Designated MEOSAR QMS Reference Beacons .......................................... 2-2
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2.4
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Guidelines for Defining Reference Beacons Requirements ....................................... 2-3
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2.4.1
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Guidelines for Supplying a MEOSAR Reference Beacon ............................ 2-3
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2.4.2
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Other Guidelines for MEOSAR Reference Beacons ..................................... 2-4
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2.5
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List of Reference Beacons in the System ................................................................... 2-6
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3.
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GUIDELINES FOR DEFINING CALIBRATION BEACON REQUIREMENTS ..... 3-1
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3.1
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Guidelines for Supplying a MEOSAR Calibration Beacon ....................................... 3-1
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3.2
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Other Guidelines for MEOSAR Calibration Beacons ................................................ 3-1
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4.
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GUIDELINES FOR BEACON SIMULATOR REQUIREMENTS AND
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SPECIFICATIONS ............................................................................................................ 4-1
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4.1
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Guidelines for Supplying a Beacon Simulator ........................................................... 4-1
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4.2
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Guidelines Unique to a Beacon Simulator ................................................................. 4-1
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LIST OF ANNEXES
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ANNEX A COMMITMENT OF THE MEOSAR REFERENCE BEACON OR
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CALIBRATION BEACON PROVIDER
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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 purpose of the Cospas-Sarsat System is to provide distress alert and location data for search and
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rescue (SAR), by using spacecraft and ground facilities to detect and locate distress signals and transmit
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the computed position and other related information to appropriate SAR authorities.
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This document contains both guidelines for administrations to implement various types of System
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beacons, as well as specifications that explicitly define requirements that must be met (shall), or are
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recommended to be achieved (should).
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1.2
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Scope
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This document describes the performance specification and design guidelines of the different types of
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beacons that are used for System purpose:
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•
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reference beacons including designated QMS reference beacons,
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•
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calibration beacons,
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•
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beacon simulators.
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The specifications for orbitography beacons used by the LEOSAR system are provided in document
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C/S T.006.
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1.3
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Reference Documents
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Reference
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Title
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C/S A.002
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Cospas-Sarsat Mission Control Centres Standard Interface Description (SID)
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C/S A.003
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Cospas-Sarsat System Monitoring and Reporting
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C/S G.003
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Introduction to the Cospas-Sarsat System
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C/S T.001
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Specification for Cospas-Sarsat 406 MHz Distress Beacons
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C/S T.003
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Description of the 406-MHz Payloads Used in the Cospas-Sarsat LEOSAR System
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C/S T.006
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Cospas-Sarsat Orbitography Network Specification
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C/S T.016
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Description of the 406 MHz Payloads Used in the Cospas-Sarsat MEOSAR System
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C/S T.018
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Specification for Second-Generation Cospas-Sarsat 406-MHz Distress Beacons
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C/S T.019
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Cospas-Sarsat MEOLUT Performance Specification and Design Guidelines
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- END OF SECTION 1 -
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2-1
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2.
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PERFORMANCE
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SPECIFICATION
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AND
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DESIGN
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GUIDELINES
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FOR
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REFERENCE BEACONS
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2.1
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Purpose
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The Cospas-Sarsat MEOSAR system is designed to provide global coverage. All MEOLUTs have the
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capability to detect and locate 406-MHz distress beacons within, at a minimum, their Declared
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Coverage Area. The location accuracy achieved is dependent on various parameters, including the
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accuracy of TOA and FOA measurements.
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MEOSAR reference beacons are deployed with characteristics particularly suited to benefit MEOLUTs
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with a view towards being used for the monitoring of MEOSAR performance and the QMS of the
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MEOSAR system. The monitoring may include the continuous oversight of one or more of the
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following MEOLUT parameters:
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•
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system detection rate,
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•
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system localisation performance (probability and accuracy),
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•
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MEOLUT throughput and single satellite-MEOLUT channel throughput,
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•
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TOA and FOA estimation accuracy of a MEOLUT.
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These beacons also provide a resource to complete the Quality Management System (QMS) objectives
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stated in section 7 of document C/S P.015 “Cospas-Sarsat Quality Manual”.
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2.2
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Requirements Common to all Reference Beacons
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The MEOSAR reference beacon network has been developed with the view that each MEOSAR satellite
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has at least one MEOSAR reference beacon in its field of view, thus allowing the monitoring of the
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performance of each MEOLUT channel (satellite/MEOLUT-antenna pair), to contribute to the overall
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MEOSAR QMS.
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To limit adverse impact on the System, including the avoidance of unnecessary channel congestion,
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Participants should coordinate at a regional level the location and installation timeline of their
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MEOSAR reference beacon(s), and shall coordinate at a Programme level through the Secretariat its
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transmission characteristics , with a view towards limiting the number of beacon bursts to the minimum
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required to ensure defined MEOSAR performance.
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Reference beacon providers shall provide technical characteristics of their beacons to the Secretariat,
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to allow this information to be published and made available on the Cospas-Sarsat website, including
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frequency and time characteristics, hex ID, transmission timing and schedule and, for SGBs, output
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filter types (i.e., transmission waveforms).
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2-2
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2.3
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Requirements for Designated QMS Reference Beacons
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This section provides technical requirements for reference beacons to be used for the purpose of the
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QMS defined in document C/S A.003.
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2.3.1
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Designated LEOSAR QMS Reference Beacons
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Text to be developed, noting the definition provided in document C/S A.003.
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2.3.2
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Designated GEOSAR QMS Reference Beacons
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Text to be developed, noting the definition provided in document C/S A.003.
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2.3.3
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Designated MEOSAR QMS Reference Beacons
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Each designated reference beacon used for QMS shall:
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•
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be listed on the Cospas-Sarsat website for QMS, along with its geographic location,
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transmission frequency, transmission schedule and, for SGBs, output filter types (i.e.,
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transmission waveforms); and
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•
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be committed for use to ensure that it can reliably be used to produce relevant QMS metrics;
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however, a designated QMS reference beacon may be used for complementary purposes.
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2.3.3.1 C/S T.001 Transmissions
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Designated C/S T.001 QMS reference beacons shall transmit a burst every 50 seconds (± 0.1 seconds)
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for a total of 12 successive bursts (i.e., for 10 minutes of beacon activation), followed by a transmission
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gap of at least 10 minutes, to ensure that the MEOLUT resets the beacon activation status, per
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document C/S T.019 section entitled “Independent Location Processing”. 30 minutes is the preferred
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duration for transmission repetition periods (TRP) (i.e., 10-minute slots of transmission followed by a
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20-minute gap in transmission), as depicted in Figure 2.1. The TRP shall be set to provide an integer
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number of transmissions per day (e.g., a 30-minute repetition period results in 48 transmission periods
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per day, a 20-minute repetition period results in 72 transmission periods per day).
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Figure 2.1: Definition of the Transmission Repetition Periods
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Designated QMS reference beacons shall use linear polarization, to be suitable for both L-band and
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S-band satellites. The reference beacon shall transmit nominally, but with a transmit power of
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35.0 ±0.5 dBm (measured at the antenna input).
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Time
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30-minute transmission repetition period
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10-minute transmission slot
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(12 bursts)
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…
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2-3
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Designated QMS reference beacons shall transmit in self-test mode, to minimize impact on the
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LEOSAR Sarsat SARP. The associated beacon message shall be coded so that no more than 18 bits
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within any sequence of 24 fixed bits match the 24 bit frame pattern for an operational beacon (i.e.,
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1111 1111 1111 1110 0010 1111), to minimize impact on the LEOSAR Sarsat SARP-3. Also to reduce
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unintended impact on Sarsat SARP-3 processors, the beacon message should not contain anywhere in
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bits 1 to 61 more than seven bits in the pattern of the word used for message synchronization by the
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Sarsat SARP-3 (i.e., 111000101)1.
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2.3.3.2 C/S T.018 Transmissions
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Designated C/S T.018 QMS reference beacons shall transmit a burst every 5 seconds for the first
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30 seconds (6 bursts) and one burst every 30 seconds up to 5 minutes of transmission (9 bursts, for a
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total of 15 bursts in 5 minutes), followed by a transmission gap of at least 10 minutes, to ensure that
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the MEOLUT resets the beacon activation status, per document C/S T.019 section entitled
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“Independent Location Processing”. 30 minutes is the preferred duration for transmission repetition
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periods (TRP) (i.e., 5 minutes slots of transmission followed by a 25-minute gap in transmission), as
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depicted in Figure 2.2.
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Figure 2.2: Definition of the Transmission Repetition Periods SGB QMS
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Designated QMS reference beacons shall use linear polarization, to be suitable for both L-band and
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S-band satellites. The SGB QMS messages shall be transmitted in self-test mode with a transmitted
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power of 35 ±0.5 dBm (measured at the antenna input)2.
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2.4
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Guidelines for Defining Reference Beacons Requirements
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2.4.1
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Guidelines for Supplying a MEOSAR Reference Beacon
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Supplying a MEOSAR Reference Beacon
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A MEOSAR reference beacon is supplied by a country accepting the commitment stated in
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Annex A and noting the operational requirements in document C/S A.003.
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1 Nonetheless, if no beacon message can be defined to avoid matching 8 or 9 bits of the Sarsat SARP-3 synchronisation
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word (e.g., no country code is available that does not match the synchronization word pattern), the reference beacon
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might transmit in normal mode on an exceptional basis, with due notice of this exception to the System.
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2 The transmit power of the QMS reference beacon shall be configurable in the range 30 to 37 dBm with 1 dB steps.
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Time
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…
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5-minute transmission slot (6+9 bursts)
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30 minutes transmission repetition period
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6 bursts, 5 seconds
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between each burst
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9 bursts, 30 seconds
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between each burst
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2-4
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Availability
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Once a MEOSAR reference beacon has been installed, its availability should be greater
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than 95%.
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Antenna Blockage
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The MEOSAR reference beacon antenna should provide the widest possible horizon.
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Location Data
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The beacon antenna location (longitude, latitude, altitude) should be provided with a three
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dimensional accuracy better than 1 m. This location should be given with respect to the
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Bureau International de l'Heure (BIH) Conventional Terrestrial System, having a reference
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ellipsoid defined as follows [or expressed in WGS84]:
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Semi-major axis
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=
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6,378,137 m
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Flattening (ellipticity)
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=
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1/298.2572
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The location of all MEOSAR reference beacons is given on the Cospas-Sarsat website
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www.cospas-sarsat.int.
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2.4.2
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Other Guidelines for MEOSAR Reference Beacons
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MEOSAR reference beacons should conform to the signal specifications defined in document
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C/S T.001 (FGB) or C/S T.018 (SGB), except for the following.
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Repetition period
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•
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FGB bursts, with a repetition period of 50 seconds, transmitting per 10-minute slots,
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•
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SGB bursts, with a repetition period of 30 seconds, transmitting per 5-minute slots.
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Beacon activation should be co-ordinated with other providers of MEOSAR reference
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beacons to prevent repeated transmission collisions.
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It should be possible to interrupt the beacon activation for some periods of time to meet the
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need for coordination of transmissions with other reference beacons or calibration beacons.
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Transmitted Frequency
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Initial frequency:
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For FGB:
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The transmitted frequency can be 406.034 MHz [10 Hz] or one of the frequency
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channels designated as “Reserved, not to be assigned” in Table H.2 of document
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C/S T.012 up to channel K (406.052 MHz) (note that channels L (406.055 MHz)
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and above should not be used).
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The transmitted frequency might be configurable to any frequency channel
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identified in Table H.2 of document C/S T.012 (i.e., including operational and
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“Reserved, not to be assigned” channels), in order to accommodate future
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evolution.
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2-5
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For SGB:
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The transmitted frequency should be 406.049 MHz [10 Hz] or 406.051 MHz
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[10 Hz].
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The exact transmitted frequency should be provided to the Secretariat by the reference
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beacon operator for publication.
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Output power (except for designated QMS beacons which shall comply with specifications in
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section 2.3)
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37 dBm 1dB
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The transmitted power should be configurable from 25 dBm to 37 dBm with 1 dB steps (note:
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this requirement is needed for possible mitigation of interference in the future, as deemed
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necessary).
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Antenna Characteristics (except for QMS beacons which shall comply with specifications in
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section 2.3)
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The beacon antenna should be located to provide visibility to the lowest possible elevation
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angles at all azimuths (i.e., least obstructed horizon).
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The antenna polarization should be either right-hand circular polarization (RHCP), left-hand
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circular polarization (LHCP) or linear polarisation (note: RHCP polarization is most
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suitable for L-band MEOSAR satellites, LHCP polarization for DASS S-band satellites, and
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linear polarization for both S-band and L-band satellites, although with attendant
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polarization losses). For LHCP and RHCP antennas, the radiation pattern should be omni-
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directional in azimuth and elevation. If selected, linear-polarized antennas should offer the
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widest coverage (radiation pattern) possible, in particular for high elevation angles.
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Wideband Interference
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If collocated with a MEOLUT, a MEOSAR reference beacon should not produce a power
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flux spectral density above -211 dB (W/m2Hz) in the 1544.0 MHz – 1545.0 MHz frequency
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band.
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Narrowband Interference
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If collocated with a MEOLUT, a MEOSAR reference beacon should not produce a power
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flux density above -168 dBW/m2 within 1 Hz of the 1544.0 MHz – 1545.0 MHz frequency
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band.
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Environmental and Operational Requirements
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The MEOSAR reference beacon is designed to be operated within a controlled environment
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consistent with the ranges below and, therefore, is not subject to the stricter thermal or other
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operational requirements specified in document C/S T.001 or C/S T.018 for distress
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beacons.
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Temperature requirements
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Operating temperature range:
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+15 o C to +40o C
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Storage temperature range:
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-20o C to +60o C
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2-6
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Built in GNSS Receiver
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A MEOSAR reference beacon may incorporate a GNSS receiver to receive return link
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messages (RLM).
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SGB Message Definition
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Using the SGB message definition from document C/S T.018, the following message
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parameters should be used:
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Bits
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Usage
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1 - 16
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specific TAC number indicating a System beacon as follows:
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•
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65,535 for calibration beacons,
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•
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65,534 for QMS beacons,
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•
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65,533 for reference beacons (other than QMS beacons),
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•
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65,532 for beacon simulators.
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If a system beacon has multiple uses, it should be coded with the highest
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applicable TAC number.
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17 - 30
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pre-assign serial number
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31 - 40
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country code
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status of homing device: shall be set to "0" (no homing device or homing device
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disabled)
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RLS function: shall be set to “0” if RLS is not enabled and set to "1" if RLS is
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enabled (e.g., RLS system testing)
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test protocol: shall be set to “1” (test protocol)
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44 - 90
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encoded GNSS location
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91 - 93
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vessel ID protocol identifier: shall be set to "111" (reserved for System testing)
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94 - 137 vessel ID: all bits defaulted to “0” or user defined (fixed)
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138 - 140 beacon type: “111” for System beacons
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141 - 154 spare bits: all bits set to “1”
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And use Rotating Field #0 with all fields with valid values
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Lifetime
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MEOSAR reference beacons should be designed for a lifetime of at least 20 years.
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2.5
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||
List of Reference Beacons in the System
|
||
The complete list of beacons, including the identification, location of each, technical characteristics and
|
||
status is provided on the Cospas-Sarsat website.
|
||
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||
|
||
|
||
- END OF SECTION 2 -
|
||
|
||
|
||
|
||
|
||
|
||
3-1
|
||
|
||
3.
|
||
GUIDELINES FOR DEFINING CALIBRATION BEACON REQUIREMENTS
|
||
3.1
|
||
Guidelines for Supplying a MEOSAR Calibration Beacon
|
||
Supplying a MEOSAR Calibration Beacon
|
||
A MEOSAR calibration beacon is supplied by a country accepting the commitment stated
|
||
in Annex A.
|
||
No more than one MEOSAR calibration beacon should be installed per MEOLUT.
|
||
|
||
Availability
|
||
Once a MEOSAR calibration beacon has been installed, its availability should be greater
|
||
than 95%.
|
||
|
||
Antenna Blockage
|
||
The MEOSAR calibration beacon antenna should provide the widest possible horizon.
|
||
|
||
Location Data
|
||
The beacon antenna location (longitude, latitude, altitude) should be provided with a three
|
||
dimensional accuracy better than 1 m. This location should be given with respect to the
|
||
Bureau International de l'Heure (BIH) Conventional Terrestrial System, having a reference
|
||
ellipsoid defined as follows [or expressed in WGS84]:
|
||
Semi-major axis
|
||
|
||
=
|
||
6,378,137 m
|
||
Flattening (ellipticity)
|
||
=
|
||
1/298.2572
|
||
The location of all MEOSAR calibration beacons is given on the Cospas-Sarsat website.
|
||
3.2
|
||
Other Guidelines for MEOSAR Calibration Beacons
|
||
MEOSAR calibration beacons should conform to the signal specifications defined in document
|
||
C/S T.001 (FGB) or C/S T.018 (SGB), except for the following.
|
||
|
||
Repetition period
|
||
•
|
||
FGB bursts, with a period between burst transmissions of 150 seconds continuously
|
||
transmitting,
|
||
•
|
||
SGB bursts, with a period between burst transmissions of 150 seconds continuously
|
||
transmitting,
|
||
|
||
Beacon activation should be co-ordinated with other providers of MEOSAR reference and
|
||
calibration beacons to prevent repeated transmission collisions.
|
||
It should be possible to interrupt the beacon activation for some periods of time to meet the
|
||
need for coordination of transmissions with other calibration beacons or reference beacons.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
3-2
|
||
|
||
Transmitted Frequency
|
||
|
||
Initial frequency:
|
||
|
||
|
||
For FGB:
|
||
|
||
|
||
The transmitted frequency can be 406.034 MHz [10 Hz] or one of the frequency
|
||
channels designated as “Reserved, not to be assigned” in Table H.2 of document
|
||
C/S T.012 up to channel K (406.052 MHz) (note that channels L (406.055 MHz)
|
||
and above should not be used).
|
||
|
||
|
||
|
||
The transmitted frequency might be configurable to any frequency channel
|
||
identified in Table H.2 of document C/S T.012 (i.e., including operational and
|
||
“Reserved, not to be assigned” channels), in order to accommodate future
|
||
evolution.
|
||
|
||
|
||
|
||
|
||
For SGB:
|
||
|
||
|
||
The transmitted frequency should be 406.049 MHz [10 Hz] or 406.051 MHz
|
||
[10 Hz].
|
||
|
||
|
||
|
||
The exact transmitted frequency should be provided to the Secretariat by the reference
|
||
beacon operator for publication.
|
||
|
||
|
||
Short term frequency stability:
|
||
|
||
|
||
The transmitted frequency should not vary more than 1 part in 1010 in 100 ms.
|
||
|
||
|
||
Frequency accuracy3:
|
||
|
||
|
||
For FGB, the frequency of transmission of each burst should be between [-0.014] Hz
|
||
and [+0.014] Hz from the declared transmission frequency.
|
||
|
||
|
||
For SGB, the frequency of transmission of each burst should be between [-0.014] Hz
|
||
and [+0.014] Hz from the declared transmission frequency.
|
||
|
||
Modulation symmetry
|
||
For FGB, the modulation symmetry, as defined in document C/S T.001, should be less
|
||
than 0.02.
|
||
|
||
Rise and fall times of the modulated waveform
|
||
For FGB, the modulation rise and fall times should be in the range 50-150 μs and maintained
|
||
within ± 1 μs of the selected value.
|
||
|
||
The modulation rise and fall times should be provided by the calibration beacon operator.
|
||
|
||
Digital Message
|
||
For FGB, the final 360 ms ± 1 percent of the transmitted signal should contain a 144-bit
|
||
message at a bit rate of 400 bps ± 0.1%.
|
||
|
||
3 The frequency accuracy values were derived from section 5.8.1 in document C/S T.019. Considering that a MEOLUT
|
||
may use two calibration beacons to calibrate its FOA measurements, and that the FOA measurement bias is required
|
||
to be below 0.02 Hz, a maximum value of 0.02/√2 = 0.014 Hz is proposed.
|
||
|
||
|
||
|
||
3-3
|
||
|
||
Timing accuracy of transmitted beacon bursts4
|
||
For FGB, the time of transmission of each burst should be between- [-1.77] μs and
|
||
[+1.77] μs from the declared transmission time.
|
||
|
||
For SGB, the time of transmission of each burst should be between [-0.14] μs and [+0.14] μs
|
||
from the declared transmission time.
|
||
|
||
The definition of the time reference point (anchor) of the transmitted bursts is identical to
|
||
the uplink TOA time reference, as defined for MF#67 in document C/S A.002.
|
||
The time reference point should be provided by the calibration beacon operator.
|
||
|
||
A round second is preferred for the time reference point of calibration beacons.
|
||
|
||
Output power
|
||
37 dBm 1dB
|
||
|
||
The transmitted power should be configurable from 25 dBm to 37 dBm with 1 dB steps (note:
|
||
this requirement is needed for possible mitigation of interference in the future, as deemed
|
||
necessary).
|
||
|
||
Antenna Characteristics
|
||
The beacon antenna should be located to provide visibility to the lowest possible elevation
|
||
angles at all azimuths (i.e., least obstructed horizon).
|
||
|
||
The antenna polarization should be either right-hand circular polarization (RHCP), left-hand
|
||
circular polarization (LHCP) or linear polarisation (note: RHCP polarization is most
|
||
suitable for L-band MEOSAR satellites, LHCP polarization for DASS S-band satellites, and
|
||
linear polarization for both S-band and L-band satellites, although with attendant
|
||
polarization losses). For LHCP and RHCP antennas, the radiation pattern should be omni-
|
||
directional in azimuth and elevation. If selected, linear-polarized antennas should offer the
|
||
widest coverage (radiation pattern) possible, in particular for high elevation angles.
|
||
|
||
Wideband Interference
|
||
If collocated with a MEOLUT, a MEOSAR calibration beacon should not produce a power
|
||
flux spectral density above -211 dB (W/m2Hz) in the 1544.0 MHz – 1545.0 MHz frequency
|
||
band.
|
||
|
||
|
||
|
||
|
||
4 The time accuracy values were derived from section 5.8.1 in document C/S T.019. Considering that a MEOLUT
|
||
may use two calibration beacons to calibrate its TOA measurements, and that the TOA measurement bias is required
|
||
to be below 2.5 µs for C/S T.001 beacons and [0.2] µs for C/S T.018 beacons, 2.5/√2 = 1.77 µs is proposed for
|
||
C/S T.001 beacons measurements and a maximum value of 0.2/√2 = 0.14 µs is proposed for C/S T.018 beacons
|
||
measurements.
|
||
|
||
|
||
|
||
3-4
|
||
|
||
Narrowband Interference
|
||
If collocated with a MEOLUT, a MEOSAR calibration beacon should not produce a power
|
||
flux density above -168 dBW/m2 within 1 Hz of the 1544.0 MHz – 1545.0 MHz frequency
|
||
band.
|
||
|
||
Environmental and Operational Requirements
|
||
The MEOSAR calibration beacon is designed to be operated within a controlled
|
||
environment consistent with the ranges below and, therefore, is not subject to the stricter
|
||
thermal or other operational requirements specified in document C/S T.001 or C/S T.018
|
||
for distress beacons.
|
||
|
||
Temperature requirements
|
||
|
||
Operating temperature range:
|
||
+15 o C to +40o C
|
||
|
||
Storage temperature range:
|
||
-20o C to +60o C
|
||
|
||
Built in GNSS Receiver
|
||
A MEOSAR calibration beacon may incorporate a GNSS receiver to receive return link
|
||
messages (RLM) and for UTC time and frequency synchronization of calibration bursts.
|
||
|
||
Calibration Protocol (for FGB calibration bursts)
|
||
The orbitography user protocol should be used. This protocol, defined in document
|
||
C/S T.001, is as follows:
|
||
Bits
|
||
Usage
|
||
1-15
|
||
bit synchronization
|
||
16-24
|
||
frame synchronization
|
||
|
||
format flag ("0" for short message and "1" for long message)
|
||
|
||
protocol flag (set bit to "1")
|
||
27-36
|
||
country code (MID)
|
||
37-39
|
||
orbitography protocol ("000")
|
||
40-81
|
||
seven character orbitography beacon clear text identifier using the modified
|
||
Baudot code (see document C/S T.001). The seven characters shall be right
|
||
justified. Characters not used shall be filled with the "space" character (100100).
|
||
82-85
|
||
four binary zeros ("0000")
|
||
|
||
national use (set bit to "0")
|
||
108-112 national use
|
||
113-144 optional long message. National use.
|
||
The 15 hexadecimal character identification used by the MCCs describes bits 26 through 85
|
||
(i.e., 60 bits).
|
||
[A protected PDF2 field might be used.]
|
||
|
||
If the calibration beacon transmits in self-test mode, to reduce unintended impact on LEOSAR Sarsat
|
||
SARP-3 processors, the beacon message should not contain anywhere in bits 1 to 61 more than seven
|
||
bits in the pattern of the word used for message synchronization by the Sarsat SARP-3 (i.e.,
|
||
111000101).
|
||
|
||
|
||
|
||
|
||
|
||
|
||
3-5
|
||
|
||
SGB Message Definition
|
||
Using the SGB message definition from document C/S T.018, the following message
|
||
parameters should be used:
|
||
Bits
|
||
Usage
|
||
1 - 16
|
||
specific TAC number indicating a System beacon as follows:
|
||
•
|
||
65,535 for calibration beacons,
|
||
•
|
||
65,534 for QMS beacons,
|
||
•
|
||
65,533 for reference beacons (other than QMS beacons),
|
||
•
|
||
65,532 for beacon simulators.
|
||
If a system beacon has multiple uses, it should be coded with the highest
|
||
applicable TAC number.
|
||
17 - 30
|
||
pre-assign serial number
|
||
31 - 40
|
||
country code
|
||
|
||
status of homing device: shall be set to "0" (no homing device or homing device
|
||
disabled)
|
||
|
||
RLS function: shall be set to “0” if RLS is not enabled and set to "1" if RLS is
|
||
enabled (e.g., RLS system testing)
|
||
|
||
test protocol: shall be set to “1” (test protocol)
|
||
44 - 90
|
||
encoded GNSS location
|
||
91 - 93
|
||
vessel ID protocol identifier: shall be set to "111" (reserved for System testing)
|
||
94 - 137 vessel ID: all bits defaulted to “0” or user defined (fixed)
|
||
138 - 140 beacon type: “111” for System beacons
|
||
141 - 154 spare bits: all bits set to “1”
|
||
And use Rotating Field #0 with all fields with valid values
|
||
|
||
Lifetime
|
||
MEOSAR calibration beacons should be designed for a lifetime of at least 20 years.
|
||
|
||
|
||
|
||
- END OF SECTION 3 -
|
||
|
||
|
||
|
||
4-1
|
||
|
||
4.
|
||
GUIDELINES
|
||
FOR
|
||
BEACON
|
||
SIMULATOR
|
||
REQUIREMENTS
|
||
AND
|
||
SPECIFICATIONS
|
||
4.1
|
||
Guidelines for Supplying a Beacon Simulator
|
||
Antenna Blockage
|
||
The beacon simulator antenna should provide the widest possible horizon.
|
||
|
||
Location Data
|
||
The beacon antenna location (longitude, latitude, altitude) should be provided with a three-
|
||
dimensional accuracy better than 1 m. This location should be given with respect to the
|
||
Bureau International de l'Heure (BIH) Conventional Terrestrial System, having a reference
|
||
ellipsoid defined as follows [or expressed in WGS84]:
|
||
Semi-major axis = 6,378,137 m
|
||
Flattening (ellipticity) = 1/298.2572
|
||
4.2
|
||
Guidelines Unique to a Beacon Simulator
|
||
Guidelines for Functional Specifications
|
||
A beacon simulator should:
|
||
a)
|
||
Be able to simulate the burst transmissions of both C/S T.001 and C/S T.018 beacons
|
||
in accordance with those specifications;
|
||
b)
|
||
Be able to execute all test scripts for both C/S T.001 and C/S T.018 beacons as defined
|
||
in documents C/S T.005, C/S T.010 and C/S T.020;
|
||
c)
|
||
Be able to transmit C/S T.001 and C/S T.018 beacon bursts over the average burst
|
||
power range 25 dBm to 39 dBm in 1 dB steps by pre-configuration;
|
||
d)
|
||
Be able to transmit bursts at fixed invariant power and variable power levels per burst
|
||
following a pre-configured profile over time;
|
||
e)
|
||
Have transmission antenna patterns with associated EIRP values consistent with
|
||
C/S T.001 and C/S T.018 beacons for the particular beacon types being simulated;
|
||
f)
|
||
Be able to implement burst schedules including time randomization as defined in
|
||
document C/S T.001 and C/S T.018, and also transmit bursts at time-invariant rates
|
||
as defined by the pre-configuration;
|
||
g)
|
||
Be able to simultaneously transmit at least [10] beacon bursts of any combination of
|
||
C/S T.001 and C/S T.018 beacon types, with both partial and complete bursts
|
||
overlapping in time;
|
||
h)
|
||
Be able to synchronize burst transmission schedules with UTC time (see timing
|
||
accuracy specification below);
|
||
|
||
|
||
|
||
4-2
|
||
|
||
i)
|
||
Be able to simulate up to 200 C/S T.001 and up to 200 C/S T.018 simultaneous active
|
||
beacons;
|
||
j)
|
||
Be able to vary message content (e.g., GNSS encoded position) from burst to burst for
|
||
any given simulated beacon event;
|
||
k)
|
||
Be configurable in all beacon transmission parameters (e.g., by script or operator
|
||
interface) within allowed ranges in documents C/S T.001 and C/S T.018 (e.g.,
|
||
modulation index, rise time, bit rate, chip rate, chip rate variation, etc.);
|
||
l)
|
||
Be able to record, store and export to a file in a standard format (e.g., csv, xml) all
|
||
beacon transmission parameters for each burst transmission, including transmission
|
||
time stamps; and
|
||
m) Be able to generate various pulse shapes (i.e., waveform) for C/S T.018 beacons (e.g.,
|
||
half-sine, cosine, rectangular).
|
||
These functional requirements are useful for both MEOLUT commissioning tests and
|
||
system-level tests (e.g., Demonstration and Evaluation (D&E)). Items (a), (b) and (c) are
|
||
particularly useful for commissioning tests. Item (g) through (i) are particularly useful for
|
||
system capacity testing. Item (j) could be useful for evaluating message processing of
|
||
moving beacons.
|
||
|
||
Transmitted Frequency
|
||
Initial frequency:
|
||
For FGB:
|
||
The transmitted frequency can be from 406.0 MHz to 406.1 MHz.
|
||
Note that when conducting MEOLUT commissioning, FGB signals should
|
||
only transmitted in non-operational frequency channels in the upper part
|
||
of the 406 MHz band (from channel L (406.055 MHz) and above.
|
||
For SGB:
|
||
The transmitted frequency should be from 406.048 MHz to 406.052 MHz.
|
||
|
||
Short term frequency stability:
|
||
For simulated bursts, the transmitted frequency should not vary more than 1 part in
|
||
1010 in 100 ms.
|
||
|
||
Frequency accuracy5
|
||
For FGB simulator, the frequency of transmission of each burst should be between
|
||
[-0.014] Hz and [+0.014] Hz from the declared transmission frequency.
|
||
|
||
For SGB simulator, the frequency of transmission of each burst should be between
|
||
[-0.014] Hz and [+0.014] Hz from the declared transmission frequency.
|
||
|
||
5 The frequency accuracy values were derived from section 5.8.1 in document C/S T.019. Considering that a MEOLUT
|
||
may use two calibration beacons to calibrate its FOA measurements, and that the FOA measurement bias is required
|
||
to be below 0.02 Hz, a maximum value of 0.02/√2 = 0.014 Hz is proposed
|
||
|
||
|
||
|
||
4-3
|
||
|
||
Timing Accuracy of Transmitted Beacon Bursts6
|
||
For FGB simulator, the time of transmission of each burst should be [-1.77] μs and
|
||
[+1.77] μs from the declared transmission time.
|
||
|
||
For SGB simulator, the time of transmission of each burst should be [-0.14] μs and
|
||
[+0.14] μs from the declared transmission time.
|
||
|
||
The definition of the time reference point (anchor) of the transmitted bursts is identical to
|
||
the uplink TOA time reference, as defined for MF#67 in document C/S A.002.
|
||
|
||
Wideband Interference
|
||
If collocated with a MEOLUT, a beacon simulator should not produce a power flux spectral
|
||
density above -211 dB (W/m2/Hz) in the 1544.0 MHz – 1545.0 MHz frequency band.
|
||
|
||
Narrowband Interference
|
||
If collocated with a MEOLUT, a beacon simulator should not produce a power flux density
|
||
above -168 dBW/m2 within 1 Hz of the 1544.0 MHz – 1545.0 MHz frequency band.
|
||
|
||
Environmental and Operational Requirements
|
||
The beacon simulator should be designed to be operated within a controlled environment
|
||
and, therefore, is not subject to the stricter thermal or other operational requirements
|
||
specified in documents C/S T.001 and C/S T.018 for distress beacons.
|
||
|
||
Built in GNSS Receiver
|
||
A beacon simulator should incorporate a GNSS receiver to receive return link messages
|
||
(RLM) and for UTC time and frequency synchronization of bursts. This GNSS receiver
|
||
should be compatible with RLS providers.
|
||
|
||
SGB Message Definition
|
||
Using the SGB message definition from document C/S T.018, the following message
|
||
parameters should be used:
|
||
Bits
|
||
Usage
|
||
1 - 16
|
||
specific TAC number indicating a System beacon as follows:
|
||
•
|
||
65,535 for calibration beacons,
|
||
•
|
||
65,534 for QMS beacons,
|
||
•
|
||
65,533 for reference beacons (other than QMS beacons),
|
||
•
|
||
65,532 for beacon simulators.
|
||
If a system beacon has multiple uses, it should be coded with the highest
|
||
applicable TAC number.
|
||
17 - 30
|
||
pre-assign serial number
|
||
|
||
6 The time accuracy values were derived from section 5.8.1 in document C/S T.019. Considering that a MEOLUT
|
||
may use two calibration beacons to calibrate its TOA measurements, and that the TOA measurement bias is required
|
||
to be below 2.5 µs for C/S T.001 beacons and [0.2] µs for C/S T.018 beacons, 2.5/√2 = 1.77 µs is proposed for
|
||
C/S T.001 beacons measurements and a maximum value of 0.2/√2 = 0.14 µs is proposed for C/S T.018 beacons
|
||
measurements.
|
||
|
||
|
||
|
||
4-4
|
||
|
||
31 - 40
|
||
country code
|
||
|
||
status of homing device: shall be set to "0" (no homing device or homing device
|
||
disabled)
|
||
|
||
RLS function: shall be set to “0” if RLS is not enabled and set to "1" if RLS is
|
||
enabled (e.g., RLS system testing)
|
||
|
||
test protocol: shall be set to “1” (test protocol)
|
||
44 - 90
|
||
encoded GNSS location
|
||
91 - 93
|
||
vessel ID protocol identifier: shall be set to "111" (reserved for System testing)
|
||
94 - 137 vessel ID: all bits defaulted to “0” or user defined (fixed)
|
||
138 - 140 beacon type: “111” for System beacons
|
||
141 - 154 spare bits: all bits set to “1”
|
||
And use Rotating Field #0 with all fields with valid values
|
||
|
||
|
||
|
||
- END OF SECTION 4 -
|
||
|
||
|
||
|
||
|
||
|
||
A-1
|
||
|
||
ANNEX A
|
||
COMMITMENT OF THE MEOSAR REFERENCE BEACON OR CALIBRATION
|
||
BEACON PROVIDER
|
||
The installation and operation of a MEOSAR reference beacon or calibration beacon is based upon a
|
||
mutual agreement between Cospas-Sarsat and the country providing such a beacon, whereby the
|
||
Cospas-Sarsat Council accepts the proposed provision of the MEOSAR reference beacon and the
|
||
providing country agrees to abide with the following principles:
|
||
•
|
||
the host country will assume all costs of providing, operating and maintaining the beacon in
|
||
service,
|
||
•
|
||
in taking the decision where to place an orbitography, MEOSAR reference beacon or
|
||
calibration beacon, both Cospas Sarsat system requirements and the supplying country's
|
||
requirements should be taken into account,
|
||
•
|
||
the supplying country will inform Cospas-Sarsat of the precise location of the MEOSAR
|
||
reference or calibration beacon,
|
||
•
|
||
information on the MEOSAR reference beacon or calibration beacon must be provided by the
|
||
beacon operator as described in document C/S T.022,
|
||
•
|
||
the MEOSAR reference beacon should meet the Cospas-Sarsat specifications defined in
|
||
document C/S T.022,
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||
•
|
||
Cospas-Sarsat may request and/or the country supplying the beacon may decide to terminate
|
||
the operation of the MEOSAR reference beacon or calibration beacon,
|
||
•
|
||
a decision to terminate operation will be subject to coordination among Cospas-Sarsat
|
||
Participants and will not take effect until 12 months after the request/decision has been made
|
||
by one of the parties involved,
|
||
•
|
||
in case of a failure of a beacon that would be cost-prohibitive to remedy, the supplying country
|
||
will not be obliged to supply a new beacon,
|
||
•
|
||
the host country will only code reference beacons using an associated country code, as assigned
|
||
by the ITU, unless coordinated with another country to transmit a country code assigned to that
|
||
other country.
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||
|
||
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||
- END OF ANNEX A -
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||
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|
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- END OF DOCUMENT -
|
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|
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|
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|
||
Cospas-Sarsat Secretariat
|
||
1250 Boul. René-Lévesque West, Suite 4215, Montreal (Quebec) H3B 4W8 Canada
|
||
Telephone: +1 514 500 7999 / Fax: +1 514 500 7996
|
||
Email: mail@cospas-sarsat.int
|
||
Website: www.cospas-sarsat.int |