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I keep hearing various tones on a GMRS channel


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#1 tonto

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Posted 21 May 2015 - 03:36 PM

Ok, so at least once a day, I keep hearing tones on my scanner on GMRS channel 5 (I forget the freq, but it's labeled in my scanner as GMRS channel 5, so we'll assume 462.6500 (unless I find out otherwise and come back and edit))
 
So the tones are brief, and sounds like someone is rapidly dialing a touch-tone phone (so rougly 4 or 5 tones).  It's not morse code, the tones vary in sound (like a touch tone phone)
 
Anyone have any clue what might be happening?  It's annoying because it goes on for several minutes, and "ties up" my scanner (since my scanner then stops at it while it does its thing and sits idle for 2 sec waiting for more traffic before continuing the scan)

 

i've tried talking on the channel with my HT, but no one ever responds



#2 quarterwave

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Posted 21 May 2015 - 03:59 PM

Sounds like DTMF remote control, if it's a string like that. Is there a repeater on that freq?



#3 tonto

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Posted 21 May 2015 - 04:13 PM

I'm not aware of a repeater on that freq (at least nothing listed with this website).  But that's all I ever hear coming off there.  I'll keep monitoring because I'm really curious, but that's it.  Just the tones. 
 
What kind of stuff is (or can be) done using the DTMF remote control?  I'm not really familiar with that.  Maybe I could deduce who or what is using it, but I dont' really know what that's used for :)
 
I have only been attempting to communicate with them via simplex, I didn't think to try transmitting using -5 like the other repeaters (assuming it's on a repeater freq)



#4 quarterwave

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Posted 21 May 2015 - 05:29 PM

It could be a licensee, or some rougue radio dealer that setup and unsuspecting customer with SCADA-like or simple remote controlling hardware, it could very well be simplex. You can use DTMF encoder/decoders to kick on relays for various things, setup/knockdown repeaters, etc. The receiver radio basically has an output that drives a relay and then things that can be done are many...high and low voltage switching. It could also be a trigger of some sort sending the DTMF, and the receiver just goes into alarm to signify something happened....could be an alarm, alert, water level, power out, door that opened...etc. Those are some more elaborate examples, but in the radio biz I setup a fire departments' big siren on the roof of the FD to blow by remote, also setup thier garage doors to go up when a certain code was used, and a real cool one...gas pumps active for 15 minutes after a code was put through. 

 

If you are hearing a rapid string, it is pre-programmed and is likely intentional. Legit use of the freq? Probably not. 


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#5 Logan5

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Posted 25 May 2015 - 01:14 PM

DTMF or telephone touch tones  are used for many things including remote control of repeater, dialing out from a telephone interfaced repeater as well as other non radio related remote control and signaling. a local car dealer uses DTMF over 2 way radios to inform the repair shop of cars coming in for service. and to indicate customer are there to pick up. no talking just strings of DTMF tones.



#6 WQWG565

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Posted 25 August 2015 - 01:46 PM

Don't know if you ever figured this out, but it sounds like the code "call" that a Baofeng (UV-5R) puts out when in "alarm" mode.



#7 zap

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Posted 29 August 2015 - 12:20 PM

Signaling…


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