What is the meaning of the procedural signal "CQ"?

The procedural signal "CQ" means "calling any station." It is a general call used in amateur radio as a way for operators to announce their presence on a frequency and invite any licensed operator to respond. This signal indicates that the operator wants to communicate with anyone who can hear them, rather than addressing a specific individual or station.

This is particularly useful in radio communication when the operator does not know who else may be on the air or wants to reach out to multiple potential contacts at once. Using "CQ" effectively helps in gathering operators for conversation, fostering engagement and connections within the amateur radio community.

The other options, while they describe different concepts within radio communication, do not accurately capture the intended meaning of "CQ." For instance, calling on the quarter hour is not a standard procedural signal and pertains more to timing practices, while test transmissions typically imply no reply is expected, and point-to-point communications limit the interaction to one designated station rather than calling all stations.