GMDSS. FCC Test 56

Which Automatic telex command should be sent by a ship station during Sitor operations to properly address a weather report to the national weather authority?

OBS+
OBS+ then MSG+ to indicate weather report.
WX+ followed by the text of the report.
GA+ then OBS+.

Which of the following would be a valid automatic telex code and number for a request for a real-time telex connection to a shore-based telex terminal?

DIRTLX23122445+.
DIRTLX then after GA+ then sends telex number.
DIRTLX then waits for MSG+ to dial 023419645+.
DIRTLX023424998+.

The DIRTLX command should be given to a coast station at what point in time?

Sent at the beginning of the message to request a direct telex connection.
After receipt of the Go Ahead indication followed by the Automatic Exchange of Answerbacks.
Immediately following the Automatic Exchange of Answerbacks.
After receipt of the Go Ahead indication following the Automatic Exchange of Answerbacks.

Which of the following is true of Sitor ARQ mode:

The ship station sends a group of 3 characters twice and then waits for an 'RQ' signal to indicate proper receipt before continuing transmission.
The ship station sends a group of 3 characters, the shore station checks for proper parity. If parity is ok, the shore station indicates readiness for transmission of the next 3 characters.
The Ship station sends each character twice, using a Time Diversity system to ensure proper parity.
The ship station sends a group of 3 characters, the shore station checks for proper parity and then requests the same group be resent to enable error correction.

Which of the following statements concerning SITOR communications is true?

None of the above.
Weather broadcasts cannot be made in FEC because sending each character twice would cause the broadcast to be prohibitively long.
Communication is established on the working channel and answerbacks are exchanged before FEC broadcasts can be received.
Two-way communication with the coast radio station using FEC is not necessary to be able to receive the broadcasts.

What should happen when an RQ code is received by a SITOR station which is sending message traffic?

The acknowledge light should illuminate.
The last block will be resent.
The data link will break.
The next block will be sent.

When requesting a direct telex connection to a vessel's Inmarsat-A terminal, (i.e. making a sitor call to an Inmarsat-A unit) the GMDSS operator must:

DIRTLX, 0, Country code, telex number, +.
DIRTLX, 0, Ocean Area Code, telex number, +.
None of the above.
DIRTLX, 00, Ocean Area Code, telex number, +.

To correctly address a Sitor message and transmit it 'live' to a shore-based office the GMDSS operator would dial which sequence:

DIRTLX0051440344+
DIRTLX581440344+
DIRTLX05811500260+
DIRTLX051440344+

Which of the following is true of SITOR FEC in the presence of impulse-type interference?

The error rate is reduced by time diversity reception.
Transmitter and receiver cannot synchronize.
Data flow rate depends on signal propagation.
Idle characters are sent upon request.

Review Answers

GMDSS. FCC Test 56

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