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From: schley@mmm.UUCP (Steve Schley)
Newsgroups: net.auto.tech
Subject: Re: Motion sensors in car alarms
Message-ID: <560@mmm.UUCP>
Date: Tue, 25-Feb-86 10:46:37 EST
Article-I.D.: mmm.560
Posted: Tue Feb 25 10:46:37 1986
Date-Received: Fri, 28-Feb-86 06:30:28 EST
References: <8927@ucla-cs.ARPA>
Reply-To: schley@mmm.UUCP (Steve Schley)
Distribution: net
Organization: 3M Company, St. Paul, Minn.
Lines: 30
Summary: 

In article <8927@ucla-cs.ARPA> wales@ucla-cs.UUCP (Rich Wales) writes:
>What do other people on the net feel about motion/impact sensors?

I have a Clifford IMS alarm installed in my Jetta (put it in myself,
btw).  I can't say what kind of sensor they use, except that it appears
to sense impact only, being insensitive to tilt and slow motion.
Rocking the car back and forth won't set it off, but a fist against a
window or door pillar will.  It is adjustable, with a wide range of
settings available to the installer/owner.  Clifford maintains that the
proper location of this sensor in the car is critical: just above the
engine (at least in the case of front-engine cars...), and absolutely
plumb.  This would appear to place the sensor at the center of the
polar moment of the car, making sure that any impact will result in a
rolling motion when viewed from the sensor.  Anyway, it works.

I have had no falses with my IMS system.  It has warned me of possible
damage once, having parked in an urban ramp late at night.  (Another
respondent claimed that alarms won't give such warning.  They do shut
up after ~30 sec, but the IMS has an indicator lamp on the dash that
will indicate that it has been tripped and reset itself.)

Summary: If the sensor is well designed, properly installed, and carefully
adjusted, I only see advantages to having it in my car.  However, those
cheap pendulum-style units that Radio Shack and others sell are perfect
for ruining your relations with your neighbors!

-- 
	Steve Schley

	ihnp4!mmm!schley