Path: utzoo!attcan!uunet!mcvax!unido!ecrcvax!johng
From: johng@ecrcvax.UUCP (John Gregor)
Newsgroups: sci.electronics
Subject: Re: Correct Terminology
Keywords: radar, laser, lidar?
Message-ID: <120@hydra.ecrcvax.UUCP>
Date: 22 Feb 89 18:29:59 GMT
References: <603@icus.islp.ny.us> <7944@netnews.upenn.edu> <1868@tank.uchicago.edu> <142@aucis.UUCP> <1895@tank.uchicago.edu>
Reply-To: johng@hydra.UUCP (John Gregor)
Organization: ECRC GmbH, Munich
Lines: 37

In article <1895@tank.uchicago.edu> kean@tank.uchicago.edu (Keane Arase) writes:
>The laser beam will spread 3.5 feet in 1000 ft (1/5 mile!) and register
>your speed in 1/4 to 1/2 second.  (I know *I* don't have reaction
>times this fast!)  And of course there will be no *radio* leakage.

Doesn't the authority of the FCC end at a few GHz?  So, what's the
possibility of doing some sort of ECM in the visible and near visible
end of the spectrum?

For the automated-take-your-picture-and-send-you-the-bill toys, I've
thought of strongly illuminating the license plate with either near-IR
or near-UV to fog the film.  Also coating the windshield with something
that's clear at visible wavelengths but a diffuse reflector at the
near-UV would also be nice.  Any ideas for such a material?

As for the laser rangefinders/speedometers, what's a good reference for
and/or the basic theory behind coherent light detectors?

Could they perhaps be defeated by a very bright flash peaking near the
frequency of the laser without violating state laws on lights (no
flashing blues, maximum energy, etc.).  Do the lasers require a
recharge time?  Would the time required for the officer to look at his
readout, figure out that he needs to re-target and try again, and
actually do it be enough for the driver (who was alerted at the first
firing) to slow down, change lanes, or whatever?

NOTE: This is a theoretical discussion only.  I'm not advocating the
use of these things to drive like hell (if I get a Ruf Porsche I might
feel differently :-) anymore than I recommend using items gleaned from
the Anarchist's Cookbook as a means of dealing with the IRS (but it
does make me smile thinking about it).  If you have a burning desire to
talk about the ethics of speeding, Road Warrior-ish ECM, etc.  Go hold
a vote for sci.ethics (seriously, it could be very good, if moderated).

-- 

John Gregor                                       johng%ecrcvax.UUCP@pyramid.COM