C & K Systems, Inc.

Gordon S Whiting

Paul M Hoseit

Frederick W Eggers

A multisensor intrusion detection system having greatly improved immunity to false alarms is disclosed. This system employs a first sensor for sensing an intrusion in a volume of space by a first physical phenomenon and a second sensor for detecting an intrusion in the volume of space by a second physical phenomenon different from the first physical phenomenon. The first sensor generates a first signal in response to the detection of an intrusion into the volume of space, and the second sensor generates a second signal in response to a detection of an intrusion. A microcontroller generates an alarm signal upon the occurrence of one first signal and one second signal within a first interval, the occurrence of another first signal within a subsequent second interval and the occurrence of another second signal within a third subsequent interval.

Methods and apparatus for intrusion detection having improved immunity

A dual sensing intrusion detection system has a microwave channel and a PIR channel. The signal from the microwave channel is amplified by an amplifier having a substantially constant gain, and is digitized and converted into a first digital signal. The signal from the PIR detector is amplified by amplifier having a substantial constant gain and is digitized and converted into a second digital signal. The first and second digital signals are compared to a microwave threshold signal and a PIR threshold signal respectively to generate an alarm signal. The system has a thermistor to detect the ambient temperature. The PIR threshold signal can be adjusted based upon changes in static conditions from the output of the thermistor. In addition, the microwave threshold signal can be changed statically based upon long term trend of the first digitized signal. Finally, the PIR threshold signal and the microwave threshold signal can be changed based upon detection from the other respective channel due to dynamic changes in the environment.

Intrusion detection system having self-adjusting threshold

Both a motion detector and a presence detector receive doppler shifted reflected microwave radiation to detect the passage of a person or an animal in a field of view. The motion sensor is adapted to detect the passage of a person or an animal near a doorway and to actuate the doorway in response thereto, to permit the passage of the person or animal thereto. The presence detector detects 'swaying motion' of a person or an animal in a field of view much closer to the location of the sensor as its gain is much lower than that of the motion detection channel. In addition the presence detector is activated only in the event the motion sensor is deactivated. The output signals from the motion sensor and presence sensor are gated through an OR gate and to a timer to activate the door opener.

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Orangevalle, CA, United States of America

Gordon S Whiting