From: richard@crowded-house.den.mmc.com (Richard Armstrong)
Newsgroups: alt.radio.scanner
Subject: Re: 800MHz Trunked Radio System Signals
Keywords: tone radio
Date: 21 Dec 92 15:50:04 GMT
Distribution: na
Organization: Martin Marietta

In article <1992Dec18.212636.29009@mlb.semi.harris.com> rliles@spuds.mlb.semi.harris.com (Ray Liles) writes:
>In our area, all the police, sheriff and fire departments are converting to
>800MHz trunked systems by GE.
>
>At the end of the voice transmissions, there is a 4800Hz tone for about 300ms,
>followed by *musical* GE notes with more of the 4800Hz tone.  While I realize
>the musical stuff is there as an annoyance factor for scanners, is the 4800Hz
>tone always present on the end of transmission?
>
>From what I can hear and detect with a 567 tone decoder, the 4800Hz tone chops
>in and out with the musical tones, unless I'm overdriving the decoder.  If 
>anyone has the exact end of transmission info on the GE systems, I would 
>appreciate it.
>
>Ray

From what I understand, Only a select few of the GE folks actually know what
the format of their radio sequence is. (I guess the Japanese folks forgot to
mention it to GE ha.ha.)  

Welcome to the world of our government officials doing everything they can
to hide and obscure their day-to-day activities.  We need to write our
representatives to complain about our "open" government hiding their activities.

Don't get me wrong here; my father is in law enforcement. Believe me, the
last thing I want is for him to get injured or killed when making good on
arrest warrants, and the person he is arresting has a police scanner and knows
the police's every move.  I do believe in protecting the police. However, why
do we need to trunk all radio transmissions?  

Here in Denver, CO.,  on 12/20/92 at 7:30am, our Denver police department
switched over to the new GE trunked system. My ability to scan the new 
trunked system is futile.  I have a Uniden 800XLT, and filled all 40 channels
with the 40 frequencies that are assigned to the new Denver trunk system. I
locked-out the constant data channel, and started scanning. Everytime the
officer keys the mike, the system assigns a new frequency for that message.
At the end of each keying of the mike, the system randomly selects a new
frequency. The problem is the series of beeping and musical tones that clearly
are there to screw up your scanner. So you end up missing the response to the
first message.  Even if the tones could be discarded, and the radio would
ignore them, the odds of getting to the next frequency selected for that same
conversation are almost nil.  To complicate matters, they put the water and
waste companies on there, and other city functions.

This really sucks. One other note, the media (which depends on the scanner for
early deployment of newscasters) has not mentioned one thing about the switch-
over.  I suspect they were given GE trunked radios so they could monitor it.
I also wonder about the tow-trucks in town. They also relied on accident 
reporting to race to the scene. They could be put out of business as well. Here
in Denver, the tow-trucks were always first on the scene... Usually about 4
would arrive before any police or rescue equipment. I guess that goes away now.

If anyone knows how to break the format, let me know PLEASE. Denver was always
more fun to listen to than the communities around Denver.



>-------------------------------------------------------------------------------
>  \  \  \                                         |  Harris Semiconductor     
>   \--\--\                                        |  Mail Stop 58-032         
>    \ |\  \                                       |  P.O. Box 883             
>      |      WA4VME                               |  Melbourne, Florida 32902 
>      |      Ray H. Liles                         |  407-729-4640 (Office)    
>      |      rliles@heimdall.mlb.semi.harris.com  |  407-729-4029 (FAX)       
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-- 
My company never said any of this... I didn't either.
Richard Armstrong, Software Engineer, Martin Marietta
Email->>>> richard@crowded-house.den.mmc.com <<<<-Email