Abstract: A processor, such as a microprocessor, responds to the detection of an input audio signal generated by glass breakage to cause an alarm to be indicated, such as at a remotely located alarm control panel. The system determines when the input power supply voltage supplied to the system falls below a selected low voltage level. The system is placed in a test mode of operation in response to a uniquely characterized, humanly generated input sound signal and then can be tested by any appropriate humanly generated input sound signal. The system continually monitors ambient background noise and determines when an absence thereof occurs so as to provide an indication of such absence to alert the user to the possibility that the system may have been purposely comprised. The system further uses a number of indicators arranged so that the meanings thereof are different depending on whether the system is in an alarm detection mode of operation or in a test mode of operation.

Abstract: A glass fracture detection system includes a circuit having a sensor for providing an output signal when a glass fracture occurs. The sensor is positioned within a housing so that, when the housing is mounted on the surface of the glass adjacent the frame in which the glass is encased, the sensor is automatically positioned in communication with the glass surface at a specified distance from the frame, which distance is selected so as to reduce damping of the output signal due to the presence of the frame and to reduce signals reflected from the frame to the sensor.