Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uunet!tiamat!chromc!dynasys!jessea
From: jessea@dynasys.UUCP (Jesse W. Asher)
Newsgroups: sci.electronics
Subject: Re: Detecting Radar Detectors
Message-ID: <229@dynasys.UUCP>
Date: 12 Aug 90 00:57:50 GMT
References: <324@bally.Bally.COM> <2860@nems.dt.navy.mil> <1990Aug07.150400.3929@pmafire.UUCP>
Reply-To: jessea@dynasys.UUCP ()
Organization: Dynasys:  Consulting for the Future.
Lines: 34

In article <1990Aug07.150400.3929@pmafire.UUCP>, tuv@pmafire.UUCP (Mark Tovey) wrote the following:
>In article <2860@nems.dt.navy.mil> downin@dtoa1.dt.navy.mil (Dave Downin) writes:
>>On the subject of radar detectors, is there some relatively inexpensive
>>and fairly easy way to build a radar gun jammer that could opperate
>>through your stereo or cb antenna?
>
>     I have seen plans for building such a thing, however it can't work
>through the stereo or CB. It requires a fairly expensive microwave diode
>and a small horn for transmission. It was designed to be used in 
>conjunction with a detector. If the detector was triggered by a rader
>transmission, it would trigger the jammer automatically. 

This is called AECM - Active Electronic Counter Measures  -in military terms.

>     One other thing, I believe that such a device is illegal. You 
>wouldn't be able to hide it very effectively either. As soon as the police
>officer's rader unit went wild, he would know that he had been zapped and
>would start looking for the culprit.

It is indeed illegal.  You must have a license from the FCC in order to
transmit and you are not going to get one.  I have thought of building one,
myself, but I've considered it a waste of time since they would eventually
catch you.  I don't think the officers would realize what was happening
the first couple of times.  But the word would get out and they would set
a trap of some sort to catch that dastardly soul that would pull such a
hideous crime.

One other note here.  The way radars work is that waves are bounced off of
cars and the frequency is changed depending on how fast the car is going.
The radar measures the shift and approxiamates how fast the car was going
according to how much of a shift occurred.  Conceivably, you could build
a AECM unit that would detect the incoming frequency and broadcast back
some other frequency to fool the detector.  Of course, you would still have
the bounced frequency mixed in, so I'm not sure how well it would work.