What is CTCSS in Amateur Radio?

What is CTCSS in Amateur Radio?

CTCSS is short form for Continuous Tone-Coded Squelch System and is a type of in-band signaling in which a low frequency audio tone is added to the transmitted voice signal. It is also called as tone squelch. When more than one user is transmitting simultaneously on the same frequency with different CTCSS tones, those with a different CTCSS tone or no CTCSS are masked by the receiving set up in most cases. This facility available in modern VHF and UHF radios is useful while accessing CTCSS enabled repeaters. CTCSS tones range from 67 to 257 Hz. Unmuting the audio on detection of the correct CTCSS tone by the receiver is known as decoding. A very narrow bandpass filter which passes the desired CTCSS tone is used for decoding.

What is CTCSS in Amateur Radio?