🚀 go-pugleaf

> ==> A motion/impact sensor can tell whether someone has bumped into your
>     car.  If you return to your car and see that the alarm has not been
>     set off, you know you needn't inspect it carefully for damage.

Not generally correct.  By state law (at least in Massachusetts, and
probably elsewhere) auto alarms must automatically shut off after a
short interval (roughly a minute or two.)

> ==> A motion/impact sensor can set off the alarm if someone tries to
>     tow your car away.

Agree.

>     On the other hand, a thief who is brazen enough to tow away a car
>     is not likely to be deterred by an alarm.

But given a choice between your car with an alarm and someone else's
without, who's do you think he'll take?

>     I think a much more effective measure to discourage illegal towaways
>     would be to engrave the VIN number all over the car (so as to make
>     it less attractive to the "chop shops").

Presuming you do it so obviously that they see it before they steal it...
and that you don't mind defacing your pretty new car in this manner.

> ==> Motion/impact sensors contribute heavily to false alarms (especially
>     with cars in parking structures), thus fostering a "cry wolf" image
>     and eroding public willingness to take car alarms seriously.

Most often, false alarms are because the sensor was improperly mounted
or adjusted.  But granting your point that false alarms do happen and
people may/may not take notice, suppose you knew for a fact that this
afternoon, *SOMEONE'S* car was going to get stolen from the lot you parked in...
could I sell you an alarm?

Regards,

Douglas Hamilton       Prime Computer,Inc.
617-626-1700 x3956     CAD/CAM Workstation Group 
                       492 Old Connecticut Path
                       Framingham, MA  10701

{seismo,ihnp4,allegra,ut-sally}!harvard!prime!doug
-- 
Douglas Hamilton       Prime Computer,Inc.
617-626-1700 x3956     Video Products Group
                       492 Old Connecticut Path
                       Framingham, MA  10701

{seismo,ihnp4,allegra,ut-sally}!harvard!prime!doug

[I posted the following article a week ago -- but since I have seen
absolutely no feedback on it, I am assuming it was somehow lost and
am therefore posting it again. -- RBW]

Most automobile alarm systems today seem to include a "motion" or
"impact" sensor -- either a simple weighted spring, or a sophisticated
electronic device -- which sets off the alarm if the car is hit or
jarred (as, for example, during an attempted tow).

I seriously question whether these sensors are really useful.  I tend to
think they are more trouble than they are worth.

I would appreciate any comments on the following ideas:

==> A motion/impact sensor can tell whether someone has bumped into your
    car.  If you return to your car and see that the alarm has not been
    set off, you know you needn't inspect it carefully for damage.

    On the other hand, I would think that an alarm would tend to scare
    the "hitter" away -- where otherwise he might (and I repeat *might*)
    leave a note.  In such a situation, the alarm would be counterpro-
    ductive.

    As far as alerting the car owner so that he can go out to his car
    and possibly identify the other car before it leaves the scene, I
    doubt this would work unless the owner could get out to his car
    within a few seconds at most.

==> A motion/impact sensor can set off the alarm if someone tries to
    tow your car away.

    On the other hand, a thief who is brazen enough to tow away a car
    is not likely to be deterred by an alarm.  (Some people may use
    this point as an argument against *all* alarms, of course.)

    Besides, just because a car being towed has an alarm sounding off
    doesn't mean the car is being stolen (maybe it was parked illegally
    and is being towed legitimately).  So, neighbors or passers-by may
    not necessarily take any action (except to curse the racket being
    produced by the alarm).

    I think a much more effective measure to discourage illegal towaways
    would be to engrave the VIN number all over the car (so as to make
    it less attractive to the "chop shops").

==> Motion/impact sensors contribute heavily to false alarms (especially
    with cars in parking structures), thus fostering a "cry wolf" image
    and eroding public willingness to take car alarms seriously.

What do other people on the net feel about motion/impact sensors?

Since I know the subject of car alarms is almost a "religious" issue,
let me emphasize that I am asking specifically for opinions about
motion/impact sensors -- not car alarms in general.

If you do feel impelled to speak to the general issue of whether car
alarms are worth having, go ahead (how could I stop you, anyway? :-}),
but *please* be sure to change the "Subject:" line in your followup.
-- 
Rich Wales // UCLA Computer Science Department // +1 213-825-5683
	3531 Boelter Hall // Los Angeles, California 90024 // USA
	ARPA:   wales@LOCUS.UCLA.EDU  -or-  wales@UCLA-LOCUS.ARPA
	UUCP:   ...!(ucbvax,ihnp4)!ucla-cs!wales

[]
   I don't know too much about auto alarms, but I can offer some advice...
DON'T get an overly sensitive motion/impact sensor.  I live in Buffalo,
N.Y. and at times it gets a bit windy.  There is a 1985 Nissan 300-ZX
here with an alarm on it.  Every time the wind picks up to about 20 mph,
it rocks the car a little bit and....BINGO!  You have one nice bright red
car flashing its lights and making all kinds of racket, causing pedestrians
to take a rather wide path around the car so as not to be suspected of 
tampering with the car.  (BTW, it is rather funny to listen to the thing 
after a while when the battery is run way down...I guess they guy doesn't
have a pager unit...)

-- 
     Adrian Zannin
     SUNY at Buffalo Computer Science

..{bbncca,decvax,dual,rocksvax,watmath,sbcs}!sunybcs!ugzannin
CSNET:    ugzannin@Buffalo.CSNET
ARPANET:  ugzannin%Buffalo@csnet-relay.ARPA
BITNET:   ugzannin@sunybcs.BITNET

In an incident in the parking lot the other day (where a truck rolled
across the lot and into my car, causing some minor damage to the bumper
shroud) the motion sensor set off the alarm.  People nearby looked
around to see what the noise was, saw the accident, and called the
police.  They probably wouldn't have noticed anything at all without the
alarm sounding.  Thus I'm in favor of the motion sensor.  This sort of 
thing is why I got one.
	- Brian

> [I posted the following article a week ago -- but since I have seen
> absolutely no feedback on it, I am assuming it was somehow lost and
> am therefore posting it again. -- RBW]
> 
> Most automobile alarm systems today seem to include a "motion" or
> "impact" sensor -- either a simple weighted spring, or a sophisticated
> electronic device -- which sets off the alarm if the car is hit or
> jarred (as, for example, during an attempted tow).
> 
> I seriously question whether these sensors are really useful.  I tend to
> think they are more trouble than they are worth.
     				.
				.
				.
The switch is mercury activated and you can adjust how sensitive you
want it. I think you'd want it for towing pirates or hit and runners.
Most alarm systems include them and they effectively bring about 
public interest as the crime is committed.

					Joe Heneghan
					

>   I don't know too much about auto alarms, but I can offer some advice...
>DON'T get an overly sensitive motion/impact sensor.  I live in Buffalo,
>N.Y. and at times it gets a bit windy.  There is a 1985 Nissan 300-ZX
>here with an alarm on it.  Every time the wind picks up to about 20 mph,
>it rocks the car a little bit and....BINGO!  You have one nice bright red
>car flashing its lights and making all kinds of racket, causing pedestrians
>to take a rather wide path around the car so as not to be suspected of 
>tampering with the car.  

I know the 300 Z's have a pretty mushy suspension, but are you telling me
that a 20 mph wind will move the car enough to set off a motion sensor?
Must be a poor design or a bad unit.

I have a Alpine unit with motion sensor (programmable), noise sensors on the
doors, door pins and hood pins sensors, a starter breaker, and a 5 digit code,
to keep the pricks out of my car. I had a $500 stereo unit removed while the 
car was parked in my driveway. No more of that shit. If the jerk can disable
this alarm, he can have it. The cost of the alarm was only $230. It feels
good to know that my stuff is now secure. If I have a complaint, it is that
the motion sensor, even on the most sensitive setting (for cars with stiff 
suspensions)  takes a real movement to set it off. Maybe the cheap units
are not as accurate as the Alpine. I always wonder why people try to save 
money in areas where the best is barely adaquate. 

Hal Bates

> >   I don't know too much about auto alarms, but I can offer some advice...
> >DON'T get an overly sensitive motion/impact sensor.  I live in Buffalo,
> >N.Y. and at times it gets a bit windy.  There is a 1985 Nissan 300-ZX
> >here with an alarm on it.  Every time the wind picks up to about 20 mph,
> >it rocks the car a little bit and....BINGO!  You have one nice bright red
>
> .......
>
> I have a Alpine unit with motion sensor (programmable), noise sensors on the
> doors, door pins and hood pins sensors, a starter breaker, and a 5 digit code,
> to keep the pricks out of my car. I had a $500 stereo unit removed while the 
> car was parked in my driveway. No more of that shit. If the jerk can disable
> this alarm, he can have it. The cost of the alarm was only $230. It feels
> good to know that my stuff is now secure.

     Uh, not to break your bubble, but don't go feeling TOO SECURE with your
Alpine alarm. While I know absolutely nothing about Alpine alarms(they do make
good stereos), I do know that a co-worker got his radio ripped off with an
alarm system with motion detector. I noticed you work at Tek, and this happened
at good ol` Tek Beaverton IN THE MIDDLE OF THE DAY IN BRIGHT SUNLIGHT. Not
only did they get the radio, I do believe they took the alarm, to add insult to
injury. Now he just takes the radio out and brings it into work with him and
doesn't even bother with the alarm. All of this with the wonderful Tek security
team!!! (-:

Yes, motion sensors do cause false alarms.
Yes, they can detect tow-away or "bump" situations.

The best set-up for use with a motion detector is to hook it to a
Page Alert alarm (or equivalent).
The Page Alert will basically notify you of an alarm by beeping
a little pocket pager.  That way, if your alarm falses, you will
will be the only one alerted (kids like to bump cars with motion
alarms in order to get the owners to turn the system off -- or
be killed by their neighbors).  Not only that, but you can check the
situation out and either call it in to the police or "handle" it
yourself, depending on your abilities.

The Page Alerts are very inobtrusive, which is why I wish most car
alarms were made that way.

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

....
	The Robert Bosch Co. sells a modular alarm system. You buy a basic
	system and you can add the motion sensor module, the ultrasonic
	module (+others???). They are as usual expensive, but seem to
	be of rugged & sound design. (For example, if you jump or cut the wires
	to the key switch, the alarm will go off, whether the alarm is
	armed or not. Same thing with the radio. The alarm will go off
	when someone tries to steal the radio, whether the alarm is armed 
	or not. I am not sure if this is a common feature with other 
	alarms.)

	Instead of opting for a motion sensor, consider an 
	ultrasonic detector in the car's passenger compartment.
	When the car is rocked it will probably not go off unless your
	seatbelts wiggle sufficiently, or something falls over; but it
	will raise hell if someone tries to enter the car in an unorthodox
	manner (without opening the doors). 
	(Problem=>
	what if a moth is in the car...)

	In general I don't think there is a fool proof alarm system.
	If a "profesional" thief wants to get your car, he will.
	You just want to scare off the small time thieves.

	Another piece of advice: do connect the alarm to your lights
	or hazard lights. Ever heard an alarm go off on a large parking
	lot without the lights flashing? It is very hard to identify where the
	noise is coming from.

Good luck, Jan.

> 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 an alpine alarm (which I absolutely love).  It
has a motion sensor which is self leveling (couple of
servos level when the alarm sets).  For impact sensing
they put piezo microphones in the door jambs.

All the sensors are adjustable.  The only false I've had
is when it was really cold and the car 'pinged' after
being quite warm.  I had the microphones turned way up.

There is also a switch that says you have to have the
microphone AND another switch go off within a minute.