GMDSS. FCC Test 56 – Online Maritime Tests

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

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

Which of the following statements concerning SITOR communications is true?

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

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

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

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?

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

Which of the following is true of Sitor ARQ mode:

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.
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 a group of 3 characters twice and then waits for an 'RQ' signal to indicate proper receipt before continuing transmission.

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

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

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

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

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

DIRTLX581440344+
DIRTLX0051440344+
DIRTLX05811500260+
DIRTLX051440344+

Review Answers