PROGRAMMABLE VIBRATION SENSOR APPARATUS FOR PRODUCING AN ALARM SIGNAL

摘要

A user-programmable sensor system for generating an alarm signal upon detection of an alarm event is disclosed. The system is particularly suited for use in vehicle security systems. The system employs a three axes accelerometer as a shock/motion detector, and the transducer outputs are summed and the composite signal filtered to provide several channels, each covering a specific frequency or frequency band. The outputs of the channels are digitized and processed by a microprocessor. An event is characterized by seveal signal parameters with an alarm event triggered by the simultaneous occurrence of several predetermined conditions, and not just one condition. The limit values for the signal parameters which are required to qualify a shock/motion event as an alarm event may be readily programmed by the user at any time or place. The system further includes a glass breakage transducer and analyzes higher frequency components of the transducer signal to sense a glass breakage event when predetermined signal parameters are exceeded and when energy from the shock detector correlates with the glass breakage signal. The correlation with several parameters substantially reduces false alarm signals resulting from ambient high frequency noises, such as caused by passing siren-sounding vehicles or low-flying jets or helicopters.