Intrusion detection systems

Claim 2

Intrusion detection apparatus for processing a plurality of sensor signals, each of which is indicative of the level of magnetic disturbances in a distinct segment of a predetermined segmented boundary, comprising: averaging means for receiving said sensor signals, and producing a plurality of output signals which are the time averages thereof; array extractor means connected to receive said output signals from said averaging means and responsive thereto to compare the relative amplitudes of the signals received with one another, said array extractor means generating an inhibit signal if the relative amplitudes are within a predetermined range; threshold detection means, responsive to said averaged sensor signals for detecting when one of said averaged sensor signals exceeds a predetermined threshold amplitude, and upon such detection generating an activate signal; and alarm control logic, associated with said threshold detection means and said array extractor means, and operable to produce an alarm actuation signal at times when said activate signal is generated by said threshold detection means and said inhibit signal is not being generated by said array extractor means.

Claim 3

The apparatus of claim 1 wherein at least three sensor signals are received for processing, said averaging means generates at least three output signals, and said array extractor means receives and compares said three output signals.

Claim 4

The apparatus of claim 1 wherein said array extractor means receives at least three averaging means output signals and determines whether or not any one of the three received signals has a magnitude substantially greater or substantially smaller than the other two.

Claim 5

The apparatus of claim 2 wherein said array extraction means compares relative amplitudes using the criteria Am1 > (Am2 + Am3)/(K) Am3 > (Am2 + Am1)/(K) where Am1, Am2, and Am3 represent output signals from said averaging means, and K is a positive number greater than or equal to one, and upon satisfaction of both criteria, said array extractor means generates an inhibit signal.

Claim 6

The apparatus of claim 4 wherein the criteria used by said array extraction means are further defined by selecting K substantially equal to 5.

Claim 7

The apparatus of claim 1 in combination with transmission means for receiving a seismic signal indicative of seismic disturbances along said boundary; time-between-pulse means, connected to said transmission means, for processing said seismic signal to determine whether the frequency at which said seismic threshold exceeds a predetermined threshold level is above a given value, said time-between-pulse means generating a logic signal if said frequency is above the given value; and control means responsive to said logic signal to increase said threshold amplitude at which said threshold detection means generates an activate signal to a higher value.

Claim 8

The apparatus of claim 6 wherein said threshold detection means includes a first level detector for detecting when sensor signals which exceed a first predetermined amplitude and generating a first switching signal upon such detection; a second level detector for detecting when sensor signals which exceed a second, higher predetermined amplitude and generating a second switching signal upon such detection; and an activate signal generator responsive to said first switching signal to generate sAid activate signal in the absence of said logic signal, and responsive to said second switching signal to generate said activate signal in the presence of said logic signal.

Claim 9

Improved intrusion detection apparatus utilizing seismic and magnetic disturbance information, comprising in combination: seismic sensor means responsive to seismic disturbances in each of a plurality of locations along a predetermined boundary to produce a plurality of seismic sensor signals each of which is indicative of the disturbance in a distinct location; magnetic sensor means producing a signal indicative of the magnetic disturbances in one location along a predetermined boundary; seismic maximum means which receives said plurality of seismic sensor signals, and selects the largest average amplitude seismic sensor signal; a seismic signal frequency detector responsive to said largest average amplitude seismic sensor signal to detect whether the frequency of disturbances above a predetermined intensity represented thereby is below a predetermined frequency level; logic means responsive to said magnetic sensor means signal to trip and provide an alarm actuation signal when said magnetic sensor means signal exceeds a first predetermined amplitude; and control means responsive to said seismic signal frequency detector to adjust the logic means to trip at a second higher predetermined amplitude in the event that the frequency detected by said seismic signal frequency detector exceeds said predetermined frequency level.

Claim 10

Improved intrusion detection apparatus utilizing seismic and magnetic disturbance information, comprising in combination: seismic sensor means responsive to seismic disturbances in each of a plurality of locations along a predetermined boundary to produce a plurality of seismic sensor signals each of which is indicative of the disturbance in a distinct location; magnetic sensor means producing a signal indicative of the magnetic disturbances in one location along a predetermined boundary; seismic maximum means which receives said plurality of seismic sensor signals, and selects the largest average amplitude seismic sensor signal; a seismic signal frequency detector responsive to said largest average amplitude seismic sensor signal to detect whether the frequency of disturbances above a predetermined intensity represented thereby is below a predetermined frequency level; logic means responsive to said magnetic sensor means signal to trip and provide an alarm actuation signal when said magnetic sensor means signal exceeds a first predetermined amplitude; and control means responsive to said seismic signal frequency detector to adjust the logic means to trip at a second higher predetermined amplitude in the event that the frequency detected by said seismic signal frequency detector exceeds said predetermined frequency level.

Claim 11

The apparatus of claim 8 wherein said seismic signal frequency detector includes a plurality sampled averager elements, each of which receives one of said seismic sensor signals and generates at a first output, a pulse each time the amplitude of the seismic sensor signal received exceeds a said predetermined intensity, said sampled averager element further operable to provide at a second output, a signal which is the time average of the amplitude of those portions of said seismic sensor signal received above said predetermined intensity, and a time-between-pulse extractor connected to said first output of one of said sampled averager elements.

Claim 12

The apparatus of claim 9 wherein said seismic sensor means comprises a plurality of independent sensor elements; the center of the area covered by each element being at least thirty feet from the center of the area covered by each other element.

Claim 13

The apparatus of claim 10 wherein said seismic sensor means and magnetic sensor means further comprise a segmented line sensor, having three segments, each segment of which generates a combined signal indicative of seismic and magnetic disturbances in the location covered by that segment.

Claim 14

The apparatus of claim 11 and filter means operative associated with said line sensor segments for separating the portion of said combined signal representative of seismic disturbances from that portion representative of magnetic disturbances.