Abstract: An improved infra-red lens array for use in a passive infra-red intrusion sensor, which maintains high detection capability for intruders moving in the middle and near field, and yet discriminates well between the movement of intruders and of pets in the near field. The upper part of the lens array is composed of at least one row containing convex lenses, operative to focus the far and middle field radiation of the area to be protected onto the detector of the sensor. The lower part of the array has at least one row containing cylindrical lenses, with their axes of symmetry aligned vertically, operative to focus infra-red radiation from the middle and near fields onto the detector. Each cylindrical lens focuses a vertical curtain of the protected area onto the infra-red detector.

Abstract: This invention discloses a method for detecting the presence of a moving object in a detection area, including emitting a sequence of bursts of ultrasonic energy into the area, receiving ultrasonic energy reflected from within the detection area, in response to the sequence of bursts, and generating a sequence of signals respectively responsive thereto, comparing each signal in the sequence with a preceding signal, to find a variation in the signals over the sequence of bursts, and analyzing the variation in the signals to determine the presence of the moving object. Apparatus for detecting the presence of a moving object in a detection area is also disclosed.

Abstract: A method for determining malfunction of a microwave intrusion detector which transmits microwave radiation into a region and receives microwave radiation to produce a receiver signal, such that a detection pattern of microwave pulses is transmitted periodically during an intrusion detection mode, including initiating a self-test mode of the detector, transmitting during the self-test mode a test pattern comprising a plurality of microwave pulses having at least two different duty cycles, different from the detection pattern, receiving microwave radiation in the self-test mode and generating a receiver signal responsive thereto and analyzing the receiver signal to derive a parameter responsive to the test pattern, so as to determine a malfunction condition.

Abstract: An intrusion detector for supervising a region including a sensor which views a plurality of fields-of-view of the region and provides an output responsive to motion of an infrared radiation source between the fields-of-view, a first filter which provides a first filtered output based on a first, predetermined, detection pulse frequency range of the sensor output, a second filter which provides a second filtered output based on a second, predetermined, detection pulse frequency range of the sensor output and processing circuitry which receives the first and second filtered outputs and detects, in either or both of the filtered outputs, a sequence of detection pulses indicating an intrusion condition.

Abstract: A method of detecting glass breakage utilizing the sound produced by an event comprising the steps of sensing the sound and producing an electrical signal characteristic of the sound, producing a plurality of frequency band-limited signals from the sound signal, determining when a normalized rate-of-rise of a plurality of the band limited signals is above a given value specified for the particular band-limited signal and analyzing the sound signal further only if a plurality of the band-limited signals have a normalized rate-of-rise greater than their respective given value during a specified time period.