In ARQ communications, which action is least likely to cause a coast station to break the radio connection?

In ARQ (Automatic Repeat reQuest) communications, the integrity and continuity of the connection are crucial for successful data transmission. The action that is least likely to cause a coast station to break the radio connection is when an operator enters "KKKK" at the end of the message.

The "KKKK" signal serves as a standard acknowledgment in maritime communication, indicating the end of a message. It is designed to confirm receipt and does not inherently disrupt the connection or flow of communication. Instead, it is part of the protocol that ensures clear communication between stations.

In contrast, other options describe scenarios that can lead to the termination of the connection. For example, if the automatic exchange of answerbacks is interrupted by keyboard entries, this could lead to confusion in the data transmission and cause operational errors, prompting the coast station to break the connection. Similarly, if the error percentage of repeat requests becomes excessively high, it indicates significant issues with the quality of communication, which might result in the coast station deeming it ineffective to maintain the current connection. Lastly, transmitting a BRK+? command after time and charges generally signals an intention to break or reset the session, directly leading to a disconnection.

Understanding these nuances highlights why entering "KKKK