SUB-COMMITTEE ON
RADIOCOMMUNICATIONS AND SEARCH
AND RESCUE
4th session
Agenda items 3.3 and 6
COMSAR 4/3/10
16 April 1999
Original: ENGLISH
GLOBAL MARITIME DISTRESS AND SAFETY SYSTEM
Operational and technical co-ordination provisions of Maritime Safety Information (MSI) services
Note by Australia
SUMMARY
Executive summary: Proposal to optionally use ITA2, 5 bit presentation code for SafetyNET MSI broadcasts
Action to be taken: Paragraph 6
Related documents: IMO SafetyNET Manual, Joint IMO/IHO/WMO Manual on MSI (COMSAR/Circ.15)
1 The International SafetyNET Manual at Annex 6, paragraph 1.3.5, Presentation Codes (C5), requires the C5 code to be always set to '00' for International SafetyNET service messages. The use of this code implies the use of the International Alphabet No.5 (IA5) using 7 bit odd parity and provides for 128 unique symbols.
2 It is understood that the Inmarsat-C system can support Binary (8 bits providing 256 different symbols) and International Telex Alphabet Number 2 (ITA2 - 5 bits providing 32 different symbols). With the use of letter and figure modes of operation it is possible to extend the number of characters for ITA2 to 64, however, only 57 characters exist.
3 It is possible to broadcast Maritime Safety Information (MSI) in accordance with the Joint IMO/IHO/WMO Manual on MSI using ITA2. Use of ITA2 would result in significant cost savings for registered information providers providing MSI. It is understood that a cost saving of some 28.5% can be achieved.
4 It is acknowledged that some Inmarsat-C terminals may not support ITA2 at this time and the use of ITA2 is also dependent upon Inmarsat-C Land Earth Stations (LES) supporting additional SafetyNET C5 presentation codes. However, if a registered information provider's LES supports ITA2 then the option could be taken up after duly advising shipping over a period of time.
5 Given the significant potential cost savings which may be possible with the use of ITA2, Australia has referred this matter to the International SafetyNET Broadcast Coordinating Panel for consideration. In accordance with Annex 5 of the International SafetyNET Manual, COMSAR 4 is also invited to consider this issue.
Action requested of the Sub-Committee
6 The Sub-Committee is invited to consider the information provided with a view to amending the SafetyNET Manual and thus reducing the cost to registered information providers.
