Squelch tail tones?

[seligman]

I've been listening to some local chatter - on a simplex frequency - and every person's radio transmits a fancy squelch tail whenever they stop talking. It's a burst of 3 or 4 DTMF tones within half a second or thereabouts. Every person's radio sounds the same.

What types of radios have this feature? And what's the point of it?

 

[br0adband]

I've noted this myself on many conventional systems. Not sure what it is precisely but I'll guess it's either a style of CTCSS squelch control or just something that controls the repeater. But the one thing I have picked out is that I never pick up any other traffic on the same frequency except this so... maybe someone else has a better explanation of it.

Here's a sample of it from here in Las Vegas, one of the cab companies:

http://members.cox.net/bbzghost/DTMF_Squelch_Tail.mp3 (378KB, 48 seconds)

 

[n1das]

It's not any kind of "squelch tail" at all. It is DTMF ANI used to identify each radio. The other radios on the system can read and decode the DTMF tones and display the ID on their radio. Think of it as a low-tech caller ID function for the radios.

 

[rescue31210]

Radio ID'ing. Not sure what specific make radio it would be, (IE: Motorola, GE, Kenwood, etc.) Motorola usually uses MDC1200 or MDC600, GE uses GE Star, and Kenwood uses Fleetsync I and Fleetsync II. All of which sound like a Squawk before or after the user transmits.

As far as DTMF, it basically works the same way, but DTMF is a generic form of Identification, and can be found in all radios, regardless of their manufacturer.
When the user Keys up, or de-keys (POST or PRE ID) the receiving radios will display that ID number. Say for example Radio 123 has DTMF ID. When the user keys up, you'll hear 4 DTMF beeps, 1230, during which time all receiving radios that are able to Decode DTMF will display 1230 briefly.

Hope this helps.

 

[seligman]

Is there a way for people like us to decode the radio ID?

Thanks for info, by the way.

 

[mikegilbert]

Yes, Wintone or this:
http://www.qsl.net/kb5ryo/dtmf.htm

 

[rescue31210]

Is there a way for people like us to decode the radio ID?

Thanks for info, by the way.

Yes. Buy a radio that is flashed for DTMF decode and enable it through the RSS...