What is a method used to verify MF/HF NBDP two-way communication with a coast station during testing?

• A. Initiate an ARQ call to a Coast Station and wait for the automatic exchange of answerbacks
• B. Voice announcement to the coast station
• C. Morse code ping
• D. Data burst test

Answer: (A)

Verifying two-way MF/HF NBDP communication hinges on confirming a mutual data link using the proper NBDP protocol. In testing, you initiate an ARQ call to a coast station. The automatic exchange of answerbacks that follows is the built-in handshake that proves both stations can transmit and receive in the NBDP mode and that the link is functioning in both directions. If the answerbacks appear correctly, you have validated that the path, the equipment, and the mode synchronization are all working.

A voice announcement wouldn’t test the NBDP data path, since it uses voice signaling rather than the teletype/data protocol. A Morse code ping tests CW reception, not NBDP. A data burst test might check data capability, but it doesn’t provide the automatic two-way handshake verification with a coast station that ARQ exchange offers.