Data transmission on RCMP frequencies?

[Bullwinkle_01]

Hi there, my name is Matthew. I'm from Courtenay, BC. I am new to scanning, and also new to this board.

I have noticed that while listening to RCMP frequencies here, I hear what I assume to be some kind of data transmission. The best way to describe it is the same noise I used to hear when I picked up the telephone when I was on a BBS with my 2400bps modem.

If this is indeed a data transmission, how is it encoded? I'm sure that there is software I can load on my computer that can decode the transmission...

Anyways, thanks for your time!
--
Matthew.

 

[stuck22]

The data transmission your hearing is when a rural unit hits their RTT (Request to talk) button. It sends the tone to the dispatch center and alerts the dispatcher that someone wants to talk to them. The Dispatcher can then bring up that specific repeater and speak to the unit.

 

[omrail]

in Alberta when the officer hits their RTT the tone has in it the car or portable # that the RTT is coming from. so when the Dispatcher comes on it is 3A107 control 91. then on from there

 

[Chilliwack40]

What frequency are you hearing it on? I know they are in preparations for a switch to P25 digital with encryption in the very near future.

 

[Jay911]

The RTT signal sounds like MDC1200 to me, but I'm not too learned on that kind of data traffic. Also, I've never encountered a decent standalone program to decode said data bursts.

 

[Jay911]

Update: Just had to have someone point me in the direction of WinMDCD, a fine standalone program to decode MDC bursts.

RCMP, at least in Alberta, are confirmed to be using MDC1200 IDs in their RTTs. The program merrily decoded them but I didn't see who belongs to what ID as I was letting it run unattended. Now, I'm sitting here and will see what shows up.

 

[MrVelvet]

Is that what allows the RCMP dispatcher to tell which unit has requested their services?

 

[Jay911]

Yes, that's correct.

 

[Bullwinkle_01]

Well that makes a lot of sense, since I normally hear the tone & "noise" (a quick tone, less than 1 sec, and 'noise' varies in length form 1 to 3 seconds), then I hear Dispatch say "calling unit xyz111, go ahead".

Now the only issue is that I'll have to dig up my pirated copy of windows XP and install it so I can use the windows prog mentioned here.. unless I missed the link to the 'nix one!

Thanks!
--
Matthew. *who is so excited he just got a Tektronix T922R 15MHz dual trace scope from FreeCycle!*