Intrusion detection systems with turbulence discrimination
First Claim
1. An intrusion alarm system for detecting the presence of a moving target in the presence of interfering signals, comprising:
- a. means for transmitting signals into a zone under surveillance,b. means for receiving signals returned from said zone,c. processing means operative in response to said received signals to provide an output signal, indicative of said moving target and said interfering signal,d. first means for differentiating said output signal,e. second means for integrating said output signal,f. detector means coupled to said first and second means and responsive to said differentiated signal to store a magnitude proportional to said integrated signal during a predetermined periodg. threshold means coupled to said detector means and operative to provide an alarm signal when said stored magnitude is relatively constant during said predetermined period.
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Accused Products
Abstract
An intrusion alarm system employs ultrasonic frequencies and operates in the presence of turbulence. The system includes a differentiator and an integrator, each coupled to a sample and hold circuit; the differentiated pulses determining the level from the integrator, which level is stored in the sample and hold circuit during a predetermined time interval. The level, as stored, will be relatively constant for the presence of an intruder and will exhibit excursions during turbulence. A threshold circuit is responsive to the steady level during a predetermined period to sound an alarm determinative of an intrusion. During turbulence, the signal stored fluctuates and is discriminated against by the threshold circuit to assure that the alarm will not occur for this condition.
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Citations
8 Claims
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1. An intrusion alarm system for detecting the presence of a moving target in the presence of interfering signals, comprising:
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a. means for transmitting signals into a zone under surveillance, b. means for receiving signals returned from said zone, c. processing means operative in response to said received signals to provide an output signal, indicative of said moving target and said interfering signal, d. first means for differentiating said output signal, e. second means for integrating said output signal, f. detector means coupled to said first and second means and responsive to said differentiated signal to store a magnitude proportional to said integrated signal during a predetermined period g. threshold means coupled to said detector means and operative to provide an alarm signal when said stored magnitude is relatively constant during said predetermined period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification