Intrusion detection method and apparatus
First Claim
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1. An improved method for detecting the presence of an intruding object or certain other environmental changes in a protected area, the method comprising the steps of:
- (a) projecting a reference pulse of acoustical energy from a source into an area towards a reflective surface therein,(b) establishing a reference parameter (Tr) having a magnitude proportional to the interval of time elapsed between projection of said reference pulse and reflection of said reference pulse to a receiver,(c) projecting a similar pulse of acoustical energy from the source towards the reflective surface,(d) establishing an elapsed time parameter (Te) having a magnitude proportional to the interval of time elapsed between projection of said similar pulse and reflection of said similar pulse to the receiver,(e) comparing the magnitude of the elapsed time parameter (Te) with the magnitude of the reference parameter (Tr) and sensing for a variation (Δ
T) therebetween, and(f) generating an alarm in response to a variation (Δ
T).
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Abstract
A pulse echo intrusion detection method and apparatus is described wherein a reference parameter is automatically established which is representative of an interval of time elapsed during initial projection and reflection of pulse energy between a source and a receiver. The reference parameter is periodically compared with successive pulse projection and reflection time measurements in order to sense variations indicative of a changed environment such as might be caused by the presence of an intruding object.
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14 Claims
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1. An improved method for detecting the presence of an intruding object or certain other environmental changes in a protected area, the method comprising the steps of:
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(a) projecting a reference pulse of acoustical energy from a source into an area towards a reflective surface therein, (b) establishing a reference parameter (Tr) having a magnitude proportional to the interval of time elapsed between projection of said reference pulse and reflection of said reference pulse to a receiver, (c) projecting a similar pulse of acoustical energy from the source towards the reflective surface, (d) establishing an elapsed time parameter (Te) having a magnitude proportional to the interval of time elapsed between projection of said similar pulse and reflection of said similar pulse to the receiver, (e) comparing the magnitude of the elapsed time parameter (Te) with the magnitude of the reference parameter (Tr) and sensing for a variation (Δ
T) therebetween, and(f) generating an alarm in response to a variation (Δ
T). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An improved apparatus for detecting the presence of an intruding object or certain other environmental changes in a protected area, the apparatus comprising:
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(a) source means for periodically projecting a pulse of acoustical energy into an area having at least one reflective surface therein, (b) receiver means for sensing reflection of the pulses of acoustical energy, (c) sensing and comparison means coupled to said source means and said receiver means for; (1) sensing the elapsed time between the projection of each pulse by said source means and reception of the reflection thereof by said receiver means, (2) establishing a reference parameter (Tr) having a magnitude proportional to the elapsed time between projection and reception of an initial pulse, (3) comparing the reference parameter (Tr) with an elapsed time parameter (Te) having a magnitude proportional to the elapsed time between projection and reception of a subsequent pulse and sensing for a variation (Δ
T) therebetween, and(4) producing an output signal in response to a variation (Δ
T), and(d) alarm means coupled to said sensing and comparison means for receiving output signals therefrom, said alarm means generating an alarm in response to an output signal from said sensing and comparison means. - View Dependent Claims (10, 11, 12, 13, 14)
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Specification