What is the primary purpose of CTCSS in radio communications?

The primary purpose of Continuous Tone-Coded Squelch System (CTCSS) in radio communications is to allow multiple users to share a frequency without interference. CTCSS accomplishes this by sending a sub-audible tone along with the voice transmission. Only radios that are set to recognize this specific tone will open their audio path and transmit the received message, while those that do not recognize the tone will remain muted. This effectively enables different groups of users to communicate on the same frequency, as each group can use a different sub-audible tone, preventing cross-talk or interference from other users who may also be on the same channel but using a different tone.

Other options, such as improving signal strength or ensuring better voice clarity, do not directly relate to the function of CTCSS. CTCSS does not enhance the strength of the radio signal nor does it alter the clarity of the speech; rather, its main function is related to controlling access to the channel based on the specific sub-audible tone transmitted. Long-distance communication is also not its primary role, as CTCSS does not affect the range of the radio signal. Instead, its utility is more about organizing communications on shared frequencies efficiently and minimizing unwanted disruptions.