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From: csmith@plains.NoDak.edu (Carl Smith)
Newsgroups: sci.electronics
Subject: Re: measuring vehicle speed
Message-ID: <10922@plains.NoDak.edu>
Date: 22 Jun 91 04:44:49 GMT
References: <1991Jun20.024446.18473@en.ecn.purdue.edu> <4746@guppie4.UUCP>
Organization: North Dakota State University, Fargo, ND
Lines: 29

In article <4746@guppie4.UUCP> svoboda@motcid.UUCP (David Svoboda) writes:
>From article <1991Jun20.024446.18473@en.ecn.purdue.edu>, by jbs@en.ecn.purdue.edu (Spaggie):

>>  [description of laser speckle patter speed measurement system deleted]

>Outstanding.  But I could envision a problem with an inconsistant ground
>surface, as well as a problem illuminating the ground sufficiently from
>under the car to be picked up reliably by the receiver.

Although this system would avoid all the problems of tire wear, tire 
pressure, tire slip, etc, I see one real simple problem.  Dirt.  
Anything that has a direct "view" of the road surface will soon be
covered with a layer of dirt, even if the road isn't wet and muddy.
Laser beams don't go far through mud.

I don't know how this could be solved...  Maybe mount the laser and
detector behind a glass window with a little window wiper...  :)


>           Dave Svoboda, Motorola CID, RTSG, Arlington Heights, IL
>               uucp => {uunet|mcdchg|att}!motcid!svoboda
>              internet => svoboda@void.rtsg.mot.com
>           UNIX was written so a couple of hackers could run
>                           space war easier.

------------------------
Carl D. Smith Jr.
csmith@plains.nodak.edu
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