Which of the following statements concerning SITOR (NBDP) communications is true?
In ARQ, each character is transmitted twice, about 250 milliseconds apart.
Correct Answer
In ARQ, the "information sending station" will transmit a block of three characters that the receiving station will subsequentlyacknowledge or request it to be retransmitted.
In ARQ, the "information sending station" transmits a block of three characters twice, about 250 milliseconds apart.
SITOR communications can be used to contact a NAVTEX transmitting station when requesting a repeat transmission of a missed NAVTEX message.
What statement is true regarding the exchange between two stations engaged in SITOR (NBDP) communications?
In ARQ, each character is transmitted twice, with the second displaced in time from the first.
In ARQ, the "sending" station transmits a block of three characters and the "receiving" station responds with a one character Repeat Request. Following this the "transmitting" station will send a new block.
Correct Answer
In ARQ, the ISS transmits a block of 3 characters and the IRSchecks for parity. If the received block is correct a controlsignal is sentnotifying the ISS to proceed. If the paritycheckfails the block must be resent.
Broadcasts of Maritime Safety Information, traffic lists, etc. can be copied by the receiving station in ARQ mode.
Which of the following is true of SITOR (NBDP) ARQ mode:
The ship station sends a group of 3 characters twice and then waits for an "RQ" signal to indicate proper receipt before 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.
Correct Answer
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.