Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!ames!ucsd!nosc!humu!uhccux!aloha1!islenet!richard
From: richard@islenet.UUCP (Richard Foulk)
Newsgroups: sci.electronics
Subject: Re: radar countermeasures
Message-ID: <3894@islenet.UUCP>
Date: 1 Mar 88 04:30:58 GMT
References: <4596@pucc.Princeton.EDU> <20271@bu-cs.BU.EDU>
Reply-To: richard@islenet.UUCP (Richard Foulk)
Organization: Islenet Inc.,  Honolulu
Lines: 41

> >Do you think it's feasible (forget about legal for the moment because I'm
> >speaking, of course, hypothetically) to build a radar TRANSPONDER?
> >(I hear your wheels turning already)
> >[It] would send back a signal to your friendly Highway
> >Patrolman on his X or K or whatever that would register a perfectly
> >legal double nickels on the Law's satanic little radar gun's readout.
> >[...] LET ME KNOW WHY THIS COULD(N'T) WORK.
> 
> I can think of a couple of reasons why building it would be
> impractical and also why it probably wouldn't work.
> 
> Impractical:  Determining the proper time to send the
> pseudo-reflection would be relatively difficult.
> 
> As for why it wouldn't work, your car will also send back an image.
> The radar gun would get back both your image and the pseudo image that
> your transponder is sending.  This would confuse the hell out of the
> radar gun!

But it's apparently been done.  It's been a while now, but I remember
seeing ads for plans (maybe even kits) for radar spoofers in some of
the electronics hobbiest magazines.

I'm pretty sure there was even a construction article published.
Though that one billed itself as a radar calibrator -- but it did
the same thing.

If I remember correctly it was just designed to transmit a signal
that looks just like a 55mph (or whatever speed you set it to)
shift to the radar gun.  And since most of the radar guns around
currently just lock onto the strongest available signal they don't
become confused.

There was also an option to connect a radar detector to the unit
to cause it to turn on only when necessary.




-- 
Richard Foulk		...{vortex,ihnp4}!islenet!richard
Honolulu, Hawaii