Continuous Tone-Coded Squelch System (CTCSS)

Continuous Tone-Coded Squelch System (CTCSS)
Frequencies	30 MHz,800 MHz
Frequency Range	30 MHz - 800 MHz
Mode	NFM
Modulation	CW
ACF	—
Emission Designator	—
Bandwidth	5 kHz,12.5 kHz,30 kHz
Location	Worldwide
Short Description	CTCSS, also known as Private Line and Channel Guard, is a low continuous tone transmitted on NFM voice transmissions that is used to squelch and manage transmissions on a given frequency.
I/Q Raw Recording	Download file
Audio Sample

Continuous Tone-Coded Squelch System (CTCSS) is a low continuous tone transmitted on NFMNarrowband Frequency Modulation voice transmissions that is used to squelch and manage transmissions on a given frequency. This is also known as Private Line® (PL) by Motorola, Channel Guard® (CG) by General Electric and generically as tone squelch. The CTCSS system sounds like a low hum to listeners.

CTCSS is used in many analog FMFrequency Modulation public safety radios. They have a characteristic look on the waterfall, as continuous lines emanating around the center frequency carrier.