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marine board report - Off Soundings

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than its tonnage. The system also provides redundant means of distress alerting, and<br />

emergency sources of power.<br />

United States SafetyNET broadcasts include:<br />

• Navigational warning broadcasts from the U.S. National Imagery and Mapping Agency<br />

• Meteorological forecasts and warnings from the U.S. National Weather Service<br />

• Distress alerts and search and rescue warnings from the U.S. Coast Guard<br />

• Atlantic ice <strong>report</strong>s from the International Ice Patrol, U.S. Coast Guard<br />

b. SafetyNET Services. Virtually all navigable waters of the world are covered by INMARSAT<br />

satellites. Each satellite transmits Enhanced Group Call (EGC) traffic (including SafetyNET)<br />

on a designated channel at 1.5 GHz. Any ship sailing within the coverage area of an<br />

INMARSAT satellite will be able to receive all SafetyNET messages broadcast over this<br />

channel by that satellite. All INMARSAT-C maritime ship stations can monitor the EGC<br />

channel. The EGC channel can also be monitored by dedicated receive-only equipment<br />

installed separately or as part of an INMARSAT A station. (INMARSAT A is voice and data<br />

transmission system whereas INMARSAT C is a data transmissions system only.) USCG<br />

SafetyNET messages are broadcast via Telenor Satellite Services, Inc. (formerly COMSAT),<br />

a commercial satellite service provider.<br />

SafetyNET messages have five parameters: message priority, service code, address code,<br />

repetition code, and presentation code. The International SafetyNET Manual provides<br />

guidelines on the use of these parameters for SAR messages.<br />

The designation of priorities in the SafetyNET system determines the order in which a<br />

message is broadcast. INMARSAT-C is a store and forward system where messages of<br />

higher priority are placed at the head of the queue for broadcast. The two highest priorities,<br />

Distress and Urgent, also set off the alarms of certain ship<strong>board</strong> INMARSAT-C terminals,<br />

notifying the <strong>marine</strong>r that a high priority message had been received.<br />

The address code allows messages to be sent to a circular or rectangular area. The ship’s<br />

INMARSAT-C satellite terminal filters all the messages received from the satellite based on<br />

the ship’s position, entered manually or via navigational receiver. Messages are only<br />

displayed/printed if addressed to an area containing the vessel’s position. If the terminal is<br />

not connected to a navigational receiver, or the position is not updated, then it will<br />

display/print all messages broadcast over the satellite. Ships will receive all messages<br />

addressed to a NAVAREA if the user has entered the NAVAREA number into the terminal.<br />

c. USCG SafetyNET Broadcasts. U.S. Coast Guard Rescue Coordination Centers (RCCs)<br />

disseminate and monitor SAR distress related information using the INMARSAT SafetyNET<br />

system when the SAR case location is deemed to be outside the coverage of NAVTEX. In<br />

general, NAVTEX coverage extends to 200 NM off the coast. NAVTEX coverage in Alaska<br />

is limited by the length and characteristics of the coastline.<br />

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