Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!cs.utexas.edu!asuvax!ncar!umigw!rsmas!eakin
From: EAKIN@rsmas.miami.edu
Newsgroups: sci.electronics
Subject: Re: Bad News- Lasers replace Radar guns
Message-ID: <4264@rsmas.miami.edu>
Date: 19 Jan 90 14:57:07 GMT
References: <7263@lindy.Stanford.EDU> <349@egrunix.UUCP> <4236@rsmas.miami.edu> <353@egrunix.UUCP>
Distribution: na,global
Lines: 26

In article <353@egrunix.UUCP>, besler@egrunix.UUCP (Brent Besler) writes:
> 
> In general the speedometer in the cop car may be off a couple of MPH, and that
> can make big a big difference with regard to fines, etc.  Radar gun aren't 
> wired into a cops speedometer.  They use a separate radar beam to determine
> the speed of the cop car relative to the ground.

OK, so why not encorporate a small secondary radar, with a beam focused at the
ground very near the police vehicle (or even behind it) for a speed reference? 
The repeated distance measures on the target vehicle should work just as well
when both vehicles are moving.

> 
>>Now, since it's optical, it should be possible to use irregular matte finishes
>>and honeycomb materials to inhibit proper returns.  The Stealth mobile lives!
> 
> A black car is going to reflect the leat light in the near IR.  I am sure
> the IR detector in the device has to be very sensitive, as I am sure the
> desigeners too it into account.

Who said anything about black?  What we need is IR/near IR absorbance, the
visible spectrum color is independent.  For reference, look at the colored boat
tops that are selectively transparent to UV-A tanning rays.
--
C. Mark Eakin			Internet: Eakin@RSMAS.miami.edu
Univ. of Miami, RSMAS-BLR