FCC Commercial Element 9 pool, section 20

Subelement B

MF-HF-DSC-SITOR (NBDP) Equip. & Ops:

Section 20

SITOR (NBDP)-ARQ:

20B1

Which of the following statements concerning SITOR (NBDP) communications is true?

A.
In ARQ, each character is transmitted twice, about 250 milliseconds apart.
Correct Answer
B.
In ARQ, the "information sending station" will transmit a block of three characters that the receiving station will subsequently acknowledge or request it to be retransmitted.
C.
In ARQ, the "information sending station" transmits a block of three characters twice, about 250 milliseconds apart.
D.
SITOR communications can be used to contact a NAVTEX transmitting station when requesting a repeat transmission of a missed NAVTEX message.

20B1

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20B2

What statement is true regarding the exchange between two stations engaged in SITOR (NBDP) communications?

A.
In ARQ, each character is transmitted twice, with the second displaced in time from the first.
B.
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
C.
In ARQ, the ISS transmits a block of 3 characters and the IRS checks for parity. If the received block is correct a control signal is sent notifying the ISS to proceed. If the parity check fails the block must be resent.
D.
Broadcasts of Maritime Safety Information, traffic lists, etc. can be copied by the receiving station in ARQ mode.

20B2

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20B3

Which of the following is true of SITOR (NBDP) ARQ mode:

A.
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.
B.
The Ship station sends each character twice, using a time diversity system to ensure proper parity.
C.
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
D.
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.

20B3

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20B4

Which of the following keystrokes or characters follows most commands in ARQ communications when working an automated Coast Station?

20B4

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20B5

Which characters are sent by the ship station to indicate a desire to send a message via a direct connection to a shoreside TELEX subscriber?

20B5

DIRTLX = Direct (DIR) Telex(TLX)

0xx = Country code of the destination (e.g., 031 for Netherlands, 049 for Germany, etc.)

yyyy = The actual telex subscriber number on shore

Plus sign = The over/termination character

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20B6

What are the characters that are transmitted to terminate a direct TELEX connection in SITOR (NBDP) operations?

20B6

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