Miata Mailing List: April 1993, Message #74
sponsored by



     


   From: (none)
Subject: Alarms, was New person w/ an electrical question..
   Date: (none)

Gary wrote:

I have an alarm that has some sort of motion detector, but I don't know 
if its microwave or ultrasonic.  What I *do* know, is that I had to 
reduce the sensitivity since it was going off every time it rained.  Now 
the sensitivity is so low, that its difficult to set off.  It *should* 
trigger anytime someone reaches into the car.

 ...Gary
 
        I had an Alpine 8040 installed in my '92 Blue pkg B when 
        it was new. The installers did a fairly poor job, even 
        denting the trunk lid (which Dentworks fixed like magic, 
        thank goodness...). The outfit that did it is a shop in 
        Rockville, MD called anonymously enough "Car Stereo 
        Systems." It cost $500 installed.
        
        This is the Alpine unit with the microwave sensor, which 
        detects motion in 2 fields, a tight one inside the car , 
        to set off the alarm when field interruption is detected, 
        and a broad one outside of the car to detect nearby 
        gawkers/prowlers/neer-do-wells. The broad one *always* 
        gets triggerred in the rain, causing the alarm "warn" 
        mode to be activated, with little "dog-bark like" chirps 
        emitted in bursts of 4. This is apparently a design flaw 
        in the 8040... The solution (a poor one) is to 
        de-activate the broad sensor field in the rain. 
        
        This alarm does do a fine job with the most effective 
        system, however. The red LED blinks, and increases it's 
        blinking frequency when the broad sensor is triggerred.
        
        -Marc Salit 
        msalit@nist.gov