Abstract: An apparatus and method for combining detection signals generated by intrusion detection systems to provide improved alarm integrity therefor. The apparatus and method have utility with mixed sensor technology and single sensor technology detection systems. In one embodiment, analog detection signals generated by system sensors are combined in an analog multiplier and the resulting decision signal is compared via a unipolar threshold comparator or a window comparator. In another embodiment, analog detection signals are amplitude limited prior to being combined in the analog multiplier. In a further embodiment, analog detection signals are subjected to average value processing such that the decision signal has a value equal to one-half of the sum of the sensor signals. In yet a further embodiment, analog dectection signals are amplitude limited prior to average value processing.

Abstract: A self-diagnostic ultrasonic motion detection system includes an ultrasonic transceiver operative in a transmit mode and in a receive mode. In normal operation, the ultrasonic transceiver in its transmit mode has a characteristic electrical impedance. Potential electro-mechanical, electrical, acoustical, and other sources of false and failure of alarm situations manifest as changes in the electrical impedance of the transceiver in its transmit mode. The electrical impedance is monitored, changes from the nominal are detected, and a suitable self-diagnostic alarm signal is produced in response thereto.

Abstract: A motion alarm system having a combination of microwave and ultrasonic subsystems is operative to reliably detect true moving targets and to discriminate false targets both caused by target motion reflected outside the surveillance space and by noise and other interfering phenomena. Microwave and ultrasonic signals received from the surveillance space are separately processed to provide ultrasonic motion detection signals and a microwave motion detection signal. A signal processing circuit interdependently combines the signals for producing a correlated system event signal. The presence of a true moving target within the surveillance space produces sufficient correlation to cause the system event signal to meet predetermined alarm criteria. The presence of either interfering phenomena or unwanted reflected outside signals, or both simultaneously, produces insufficient correlation to cause the system output signal to meet the predetermined criteria.