Which of the following would be a valid SELCAL for ARQ communications?

Which of the following would be a valid SELCAL for ARQ communications?

• A. 1106
• B. 212420 WHAQ X.
• C. Four marks (ones) and three spaces (zeros).
• D. Established by the communications protocol.

Answer: (A)

In this context, the correct answer is based on the specific formatting and requirements for SELCAL (Selective Calling) in ARQ (Automatic Repeat reQuest) communications. SELCAL codes are used in aviation to allow ground stations to call individual aircraft without having to broadcast to all aircraft, and they usually consist of four letters, each corresponding to a specific aircraft. The option containing "1106" is a valid SELCAL in terms of being in a simple numerical format, which is acceptable in some cases to represent a code through numeric means. This aligns with the nature of ARQ communications, which often use numerical data for efficient transmission and error-checking processes. In contrast, the other options present more complex formats or invalid constructions for ARQ communications. For instance, a format such as "212420 WHAQ X" introduces complications by using both numbers and letters in the context not typically utilized within SELCAL coding. The option indicating "Four marks (ones) and three spaces (zeros)" does not conform to SELCAL coding standards, which do not include binary or simplistic count patterns. Lastly, stating that the SELCAL is "Established by the communications protocol" does not specify a valid SELCAL code but rather refers to a procedural aspect that does not

In this context, the correct answer is based on the specific formatting and requirements for SELCAL (Selective Calling) in ARQ (Automatic Repeat reQuest) communications. SELCAL codes are used in aviation to allow ground stations to call individual aircraft without having to broadcast to all aircraft, and they usually consist of four letters, each corresponding to a specific aircraft.

The option containing "1106" is a valid SELCAL in terms of being in a simple numerical format, which is acceptable in some cases to represent a code through numeric means. This aligns with the nature of ARQ communications, which often use numerical data for efficient transmission and error-checking processes.

In contrast, the other options present more complex formats or invalid constructions for ARQ communications. For instance, a format such as "212420 WHAQ X" introduces complications by using both numbers and letters in the context not typically utilized within SELCAL coding. The option indicating "Four marks (ones) and three spaces (zeros)" does not conform to SELCAL coding standards, which do not include binary or simplistic count patterns. Lastly, stating that the SELCAL is "Established by the communications protocol" does not specify a valid SELCAL code but rather refers to a procedural aspect that does not