We have designed a burglar alarm consisting of a glass-break detector and control unit. The alarm was developed from tough requirements: There was no tolerance for false alarms but yet the sensor had to be small in size with extremely low power consumption and a cost-effective production. This particular sensor is extremely good at detecting the dissimilarities between a real break-in attempt and just another touch on the glass. To distinguish between these situations and to prevent all false alarms, we developed a very complex algorithm that was one of the key building blocks in the design.