General question about "end transmission noise"

[MrRevesz]

Basically as the title says, I decided to whip out the ol' ICV8 and put in my county's EMS, Hazmat and State Police county-wide channels... One of the State Police ones have a funny end transmission beep I've never heard before and just wondering if someone can identify it, or the radio he's using....

http://idisk.mac.com/jon.maimone/Public/Sound.mp3

here's the sound clip

 

[KC0QNB]

Sounds like a dtmf ani (dual tone multi frequency (touch tone) automatic number identification).
there is a shareware program that will decode that and other types of ani.
Just can't think of it right now.

 

[SLWilson]

Fast D T M F tones

It IS the tones he mentions above.

We transmit them from our office to activate weather warning sirens....Sound just like that.

I'm not sure "how" they are using them, but, at our facility, we have the different siren functions pre-programmed into our Zetron radio consoles.

The sirens will do yelp sounds, wail sounds, hi-lo sounds, steady tones sounds and allow the dispatcher to speak over them like a PA system....

Steve/Gallia 911

 

[btritch]

We have a fire department here in the county, Theirs do the same thing.. when they unkey that is... I don't know why, they just started it but that's what it is...

 

[KC0QNB]

In some cases they are used to ID the radio/unit there are also some that come on before the voice part of the transmission.

 

[N9NRA]

Our State Patrol (WI) does that too, sometimes i find it kinda anoying, mostly `cause both my Ham radio and scanner don`t get rid of the squeich tail (the blast of static on the end), so i hear those tones. When i first herd `em i thought they were LTR tones, but i was wrong. N9NRA

 

[b7spectra]

One of the local school bus systems has that at the end of their transmissions as well.

N9NRA - Don't ever say you were wrong, rephrase it by saying "I'm never wrong, I may not be right all the time but I'm never wrong!"

 

[N9NRA]

Hey you`re right there! Anyway, i was thinkin` and also thought those tones might have been DSQ (DTMS squelch) as well, some of us Hams that had HT`s that had this feature will recall that, and my old handheld could decode the tones, although not how ya wanted `em to be decoded (if the tones are sent at the start of transmission, ya could use the DSQ feature to filter out anyone not sending that sequence of DTMF tones). Neat feature i thought. N9NRA

 

[blackacid]

The dtmf from that file is 0*1099.

I'm sure all of this has been covered but I'll add my .02 in the mix as if it were worth that much.

Usually it is used to identify whom is talking. Around these parts it is used on the EMS channels and sometimes the Fire Dept at the end of their transmissions. Whenever they unkey whoever has a radio that will decode/display dtmf will show it on the display. Sometimes the dispatcher will have a console that will display it as well. You can either have it to do it at the start or the end of a transmission. Most of the times it is at the end as if it were at the beginning you would have to wait for it to finish sending the tones in order to speak which could take up valuable time. Could also be used for man down. Hit the lil emergency button and your radio id is transmitted. Good for older radios that don't have fleetsync, mdc, or the like.

It could also be used as something like two tone paging. When the radio detects a certain dtmf sequence the radio beeps. Usually though this would be at the start of the transmission. The radio detects the dtmf and unmutes. This works the same way as activating certain sirens and whatnot as well. DTMF can even be used as stun codes. If someones radio were to be stolen.... you would send out the stun code for that radio and the radio will go into lock down mode where it is not usable until it is destuned.

And last.... some people do it just to be "cool" with a bunch of random numbers.

 

[MrRevesz]

thanks all for the information, it's one of the better sounds i've heard so far...

 

[SCPD]

Hey. I watched the radio sound noise and I have been hearing that same sound here in Jersey. Morris County Comm Center!!

 

[MrRevesz]

Hey. I watched the radio sound noise and I have been hearing that same sound here in Jersey. Morris County Comm Center!!

Probably hearing the same thing