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From: ron@brl-tgr.ARPA (Ron Natalie )
Newsgroups: net.ham-radio
Subject: Re: Commercial FM "tweedle"
Message-ID: <11380@brl-tgr.ARPA>
Date: Thu, 4-Jul-85 20:30:04 EDT
Article-I.D.: brl-tgr.11380
Posted: Thu Jul  4 20:30:04 1985
Date-Received: Thu, 11-Jul-85 05:41:29 EDT
References: <85@biomed.UUCP>
Organization: Ballistic Research Lab
Lines: 15

> 
>         Living around Boston, I have heard several walkie-talkies that the
> transit police carry and also the EMS ambulance people.  They all seem to be
> Motorolas.  Anyway, it seems that when the base station releases its mike
> key, a couple of single tones are transmitted, very rapidly, one after
> another, each about 100mS long, with no space in between them, the first
> tone higher in freq than the other.  One is about 1.5kHz and the other a bit
> lower, maybe around 1kHz.  WHAT are these for?
> 
Baltimore City has the{k bleedles.  They are a data burst.  They transmit
call information to the stations and engines.  The officer in the engine
just pushes the buttons to indicate the situation on arrival at the scene.
I think the trade name is something like MODAC.

-Ron