Which of the following is a function of CTCSS tones?

• A. To allow communication over greater distances
• B. To identify the transmitting station
• C. To reduce interference from other users on the same frequency
• D. To increase audio quality of the transmission

Answer: (C)

CTCSS, or Continuous Tone-Coded Squelch System, is primarily used to reduce interference from other users operating on the same frequency. This is achieved by transmitting a specific low-frequency tone along with the voice signal. When a receiver is set to recognize that specific CTCSS tone, it will only open the squelch and allow audio to pass through if the received signal includes the correct tone. As a result, even if there are other stations transmitting on the same frequency, the receiver will only respond to signals that include the designated tone, effectively filtering out unwanted noise and communications.

This functionality is particularly useful in crowded bands where multiple operators may be communicating simultaneously, providing a way for groups to communicate with one another without hearing every other station's chatter on the same frequency. The other options, although related to radio operation, do not describe the primary purpose of CTCSS.