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The following paragraphs have been copied from the COSPAS-SARSAT homepage (with permission of C/S).
For further deatils please see the link:
http://www.cospas-sarsat.org/index.php?option=com_content&view=article&id=229%3Acospas-sarsat-ship-security-alerting-system&catid=29%3Acospas-sarsat-website&Itemid=218&lang=en
Implementation Details
There are two major elements to the 406 MHz SSAS: the transmitter required for initiating SSAS alerts and a methodology for distribution of SSAS alert messages in the Cospas-Sarsat Ground Segment.
A specific 406 MHz beacon coding protocol defined in document C/S T.001, "Specification for Cospas-Sarsat 406 MHz Distress Beacons", will be used to discriminate a ship security alert from a distress alert. The agreed specification for the SSAS beacon provides for accurate Global Navigation Satellite System (GNSS) encoded location information in the beacon message and requires the inclusion of the vessel MMSI for the beacon identification. The specification prohibits use of a homing device in order to keep beacon transmissions covert.
The Cospas-Sarsat specification only deals with the electrical and transmission requirements that ensure the compatibility of the SSAS beacon with the satellite processing system. National Administrations and standards organizations (e.g., RTCM in the United States) are in the process of defining additional requirements for 406 MHz SSAS beacon activation and installation.
Alert Distribution Procedures
The distribution of SSAS alerts within the Cospas-Sarsat Ground Segment will occur using a modified version of the standard data distribution procedure. As in normal Cospas-Sarsat operations, all Local User Terminals (LUTs) will receive the 406 MHz SSAS beacon messages, retrieve the GNSS encoded location, and generate a Doppler location (LEOLUTs only). The ship security alert data will then be passed to a Mission Control Centre (MCC) where it will be automatically routed to the MCC that serves the Flag State identified in the beacon message, regardless of the physical location of the beacon. That MCC will then deliver the ship security alert to a single point of contact identified by the Flag State as its "competent authority", per SOLAS Chapter XI-2 Regulation 6.2.1. In the Cospas-Sarsat implementation of SSAS, a vessel will not be able to send a ship security alert directly to its Company. A sample alert message can be found below.
Noting that a detailed contacts list of the "competent authorities" has not yet been published, Administrations that decide to use the Cospas-Sarsat System for ship security alerting should contact their supporting Cospas-Sarsat MCC to coordinate a method for distribution of SSAS alerts. The MCC serving a given Flag State can be identified in document C/S A.001, "Cospas-Sarsat Data Distribution Plan", Annex I/D; contact information for the MCC can be found in Annex II/A.
SIT 185
406 MHz SHIP SECURITY ALERT
(to be transmitted only to competent security authority)
(LEOSAR - with encoded position)
1. SHIP SECURITY COSPAS-SARSAT POSITION RESOLVED ALERT
2. MSG NO. 17002 UKMCC REF 12345
3 . DETECTED AT 10 JUL 04 2130 UTC BY SARSAT 09
4. DETECTION FREQUENCY 406.0281 MHZ
5. COUNTRY OF BEACON REGISTRATION 232/G.BRITAIN
6. USER CLASS - SHIP SECURITY WITH ENCODED POSITION - MMSI LAST SIX DIGITS 387718
7. EMERGENCY CODE - NIL
8. POSITIONS
RESOLVED - 55 23.2N 022 29.9W
DOPPLER A - 55 19.1N 022 25.4W
DOPPLER B -
ENCODED - 55 23.2N 022 27.0W UPDATE TIME UNKNOWN
9. ENCODED POSITION PROVIDED BY EXTERNAL DEVICE
10. NEXT PASS TIMES
RESOLVED - 10 JUL 04 2201 UTC
DOPPLER A - NIL
DOPPLER B - NIL
ENCODED - NIL
11. HEX ID 1D18BD50C0FFBFF
12. ACTIVATION TYPE - MANUAL
13. BEACON NUMBER ON AIRCRAFT OR VESSEL - NIL
14. OTHER ENCODED INFORMATION
A. ENCODED POSITION ACCURACY - 4 SECONDS
15. OPERATIONAL INFORMATION
REGISTRATIONAL INFORMATION AT UKMCC
TELEX: 75194 UKMCCK G
AFTN: EGQPZSZX
TELEPHONE: (44-1343) 836015
16. REMARKS - THIS IS A SHIP SECURITY ALERT. PROCESS THIS ALERT ACCORDING TO RELEVANT SECURITY REQUIREMENTS.
END OF MESSAGE
