In radio communication, what does "CQ" signify?

The term "CQ" in radio communication is widely recognized as a general call to all stations. When a radio operator sends out "CQ," they are inviting any operators listening on the same frequency to respond, making it a way to reach out broadly rather than targeting a specific individual or station. This is particularly useful in situations where an operator wants to communicate with anyone available rather than waiting to know who is on the air.

The other options suggest very specific or narrow types of communication. A distress signal refers to calls that indicate an immediate need for help, which is a different context from the general invitation that "CQ" represents. A specific call sign indicates communication directed to one particular station, and an emergency broadcast involves urgent situations requiring immediate attention, both of which are not the intent behind using "CQ." Understanding this helps users of radio communication appreciate the terminology and its applications.