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Author Topic: That sound when a police radio keys up  (Read 2885 times)
MDNITERDER
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« on: February 03, 2012, 10:29:24 AM »



 They have that distinct squawk sound, or an odd chirp/crunch sound, is this something that was built into the radio, is it a brand specific?

 I have always wondered this.

John
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KB2FCV
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« Reply #1 on: February 03, 2012, 12:49:44 PM »

That is usually an identifier which identifies who the radio belongs to. It might be a vehicle number or an officer number. We had a system in place for a while for our fire radios. Officer's radios each had their own number which Identified who it was. Trucks had theirs also. The dispatcher could see who was keying up and also portables / radios would display that info too. This all has to be programmed within the radios.

Our systems are all digital trunking now, but they still transmit the same information.. however you won't make anything out on a conventional scanner as voices are all digitized (not unlike a standard cell phone today).

I'm not sure about if it is brand specific or not.
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N0FPE
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« Reply #2 on: February 03, 2012, 12:59:24 PM »

the motorola version of this is/was called MDC1200. Other brands called it different forms of ANI

Can be heard at the beginning and some times the end of each transmission

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KB2FCV
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« Reply #3 on: February 03, 2012, 01:15:53 PM »

the motorola version of this is/was called MDC1200. Other brands called it different forms of ANI

Can be heard at the beginning and some times the end of each transmission

Yep, that's the one I know of for Motorola. It was all just a matter of programming whether you wanted it before or after. All a matter of preference. The only thing with programming it before is you have to wait a second or two before you speak. Most of the radios you can turn on a beep when you key it.. when it stops beeping you can then talk, meaning it completed its digital transmission. We had it on before, I guess so the dispatcher can see who is talking as they are speaking.
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MDNITERDER
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« Reply #4 on: February 03, 2012, 02:32:17 PM »

 
 I've listened to my scanner for years, and I've always wondered what it was, just sounded like a hash of noise when they first keyed up, Sheriff's radios didnt do it just LAPD and would yea some were at the end of transmission.
 
 Now I know.
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NO2A
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« Reply #5 on: February 03, 2012, 02:44:07 PM »

Ever notice how the officer responding to the dispatcher`s call always sounds undermodulated? Like they`re talking a foot away from their mic.
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MDNITERDER
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« Reply #6 on: February 03, 2012, 03:54:09 PM »

Yes i have noticed that.
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AA4PB
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« Reply #7 on: February 03, 2012, 03:56:40 PM »

The newer radios may also be transmitting the car's GPS position in the data burst.
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W5TTW
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« Reply #8 on: February 03, 2012, 08:21:47 PM »

Ever notice how the officer responding to the dispatcher`s call always sounds undermodulated? Like they`re talking a foot away from their mic.
Could be because the LEO is wearing his HT mike on his shoulder applet and not turning directly to it to speak because he doesn't want to take his eyes off of the violator or sweet thing he's flirting with.  (X-cop)
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K1CJS
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« Reply #9 on: February 07, 2012, 04:57:40 AM »

Ever notice how the officer responding to the dispatcher`s call always sounds undermodulated? Like they`re talking a foot away from their mic.

'TTW just said it--Most of the time that is because they're speaking into a mike that is clipped to their shoulder--not because they're speaking directly into their vehicle mike.
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