Capacitive sensing security system
First Claim
1. In a security system having a plurality of sensors arranged in an intrusion defining array, a plurality of separate signal input circuits respectively connected to at least two of the sensors, means connected to the input circuits for generating signals in response to uniform and localized disturbances of said sensors in the intrusion defining array, detector means connected to the signal generating means and the signal input circuits for producing a plurality of separate signal outputs that are directional functions of said disturbances and signal processing means operatively connected to the detector means for rejecting common mode signal components of the signal outputs caused by the uniform disturbances of the sensors to extract intrusion identifying data from the signal outputs.
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Abstract
Separate signal input circuits respond to intruder disturbances of a capacitive wire sensing grid to generate signal outputs processed to reject signals caused by environmental phenomena with a high degree of statistical probability, by comparison of individual signal outputs with an averaged signal output from all of the signal input circuits.
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Citations
16 Claims
- 1. In a security system having a plurality of sensors arranged in an intrusion defining array, a plurality of separate signal input circuits respectively connected to at least two of the sensors, means connected to the input circuits for generating signals in response to uniform and localized disturbances of said sensors in the intrusion defining array, detector means connected to the signal generating means and the signal input circuits for producing a plurality of separate signal outputs that are directional functions of said disturbances and signal processing means operatively connected to the detector means for rejecting common mode signal components of the signal outputs caused by the uniform disturbances of the sensors to extract intrusion identifying data from the signal outputs.
- 7. In a security system having a plurality of sensors arranged in an intrusion defining array, a plurality of separate signal input circuits respectively connected to different pairs of the sensors and means connected to the signal input circuits for generating signals in response to uniform and localized disturbances of said sensors in the intrusion defining array, detector means connected to the signal generating means for producing separate signal outputs that are directional functions of said disturbances and signal processing means operatively connected to the detector means for differentiating between said functions of the uniform and localized disturbances to extract intrusion identifying data from the signal output.
- 15. In an intrusion detection system having a plurality of capacitive sensor elements exposed to the environment in which intrusion is to be detected, a plurality of signal circuits, means applying drive to each of said signal circuits for generating signals in response to disturbances of the environment of said sensor elements, detector means connected to the signal circuits and operating synchronously with said drive applying means for obtaining signal outputs from the detector means reflecting said disturbances of the environment of said sensor elements and signal processing means for rejecting common mode signal components, the improvement comprising array establishing means connecting different pairs of the sensor elements to each of the signal circuits for rendering the signal outputs of the detector means independent of each other prior to said rejection of the common mode signal components and intrusion indicating means connected to the detector means for receiving intrusion identifying data from the signal processing means free of the common mode signal components, said signal processing means including means connected to the detector means for averaging the independent signal outputs of the detector means and comparator means connected to the detector means and the averaging means for extracting the intrusion identifying data from the independent signal outputs by said rejection of the common mode signal components.
Specification