Sub-audible tone (CTCSS / PL)
A very low tone mixed under FM voice so that a repeater or radio only opens for the right users. Also called a PL tone.
ModeSub-audible tone
FamilyTone signaling
Audio exampleComing
What does it sound like?
Plate 63Tone signaling
Usually filtered out, so you often can't hear it at all; sometimes a faint low hum.
Field marksOne steady tone between 67 and 254 HzRuns under the voice the whole time
Who uses it?
Repeaters, businesses and family radios.
Where and when can I hear it?
Under FM voice on VHF/UHF. The tone itself is between 67 and 254.1 Hz.
What do the decoded parts mean?
- Tone frequency: The tone in Hz (for example 100.0 or 127.3). Knowing it lets you program a radio to use that repeater.
Easily confused with
- Digital squelch code (DCS), from the same family