[MarcoFranssen]

i just instaled the oem security system. bud whats the function of the microphone ?? i tryed some things, bud ...... nothing !!??

 

[protaganis]

Glass break sensor, glass breaks with a very particular frequency, the mic is designed to pick up that frequency.

 

[AztecRol]

If you jiggle your keys just right in front of the mic, it should go off.
It may take several tries, and it may not work. Try it and let us know.

 

[MarcoFranssen]

only glass break ?? Hmmm ...... i thought it was a ultrasoon sensor. i try the key thing.
buf further the new oem alarm works great. and it took only 1 hour to instal.

 

[protaganis]

To do ultrasonic, there'd need to be an audio speaker, and it'd need to be where it could send and receive a large audio "footprint".
It works by sensing a change in audio return.
They explain it very well in an episode of Mythbusters.