Hughes Aircraft Company

Daniel R Ledbetter

Robert J Cinzori

An intrusion system detects changes in background radiation received from a plurality of orthogonally arranged fields of view (FOV) which preferably are defined by thin polyhedrons coextensive with the walls of the room. These fields of view are generated by a plurality of orthogonally arranged optical reflectors located in certain corners of the room, and any changes in background radiation within these fields of view are detected by one or more thermopile detectors which are optically aligned with the above optical reflectors. The low level - low frequency output signal voltages form the thermopile detectors are converted to an AC signal and amplified for use as an intrusion alarm signal.

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Goleta, CA, United States of America

Daniel R Ledbetter