Element 7R: Restricted GMDSS Radio Operating Practices

effective 8/01/2006

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7R-A-37: NAVTEX-1: Operations

7R-37F1: How is mutual interference among NAVTEX stations avoided?

Both b) and c).

Stations are limited to daytime operation only.

Transmitter power is limited to that necessary for coverage of assigned area.

Transmissions by stations in each NAVAREA are arranged in a time-sharing basis.

7R-37F2: When do NAVTEX broadcasts typically achieve maximum transmitting range?

Middle of the night

Local noontime


Post sunrise

7R-37F3: What should a GMDSS Radio Operator do if a NAVTEX warning message is received but it contains too many errors to be usable?

Do nothing. Vital NAVTEX messages will be repeated on the next scheduled broadcast.

Contact the NAVAREA coordinator and request a repeat broadcast.

The hurricane will be upon the vessel; they're in big trouble.

Listen to appropriate VHF weather channel for repeat warnings.

7R-37F4: What does a NAVTEX receiver do when it runs out of paper?

It will give off either an audible and/or visual alarm.

The unit cannot operate, and all subsequent MSI broadcasts are missed until the paper is replaced.

The system will automatically change from receiving MSI by NAVTEX to receiving it by SafetyNETTM so that no messages will be lost.

All of the above

7R-37F5: Which of the following is the primary frequency that is used exclusively for NAVTEX broadcasts internationally?

518 kHz

2187.5 kHz

4209.5 kHz

VHF channel 16 when the vessel is sailing in Sea Area A1, and 2187.5 kHz when in Sea Area A2.

7R-37F6: What is the transmitting range of most NAVTEX stations?

Typically 200-400 nautical miles (360-720 km).

Typically 50-100 nautical miles (90-180 km) from shore.

Typically upwards of 1000 nautical miles (1800 km) during the daytime.

It is limited to line-of-sight or about 30 nautical miles (54 km).

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7R-A-38: NAVTEX-2: Programming