US3686658A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Intrusion detector responsive to change in dominant frequency
Assignee: Teledyne Geotech
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Filing: 1970-05-12
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Granted: 1972-08-22
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Expires: 1990-05-12
Abstract
Abstract An intrusion detector system using a geophone to sense both ambient or environmental events, as well as man-made or cultural events, and the system being responsive to a reduced number of zero-axis crossings of the geophone output resulting from the superimposing of man-made events upon ambient events to detect intrusions. Zero-axis crossings are represented in a long-term memory and in a short-term memory or accumulator, and their contents are compared to determine when short-term conditions change as compared with averaged long-term conditions representing mainly environmental events. In one embodiment, when an intrusion is detected in this way the system requires at least one more such detection before setting off an alarm. The memory is updated with more recent information, but only when conditions appear to be ambient, and relatively free of unusual events.
Inventors
- 👤 Marvin D Wilt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 06:41
CPC Classifications
G; G08; G08B; G08B13/00; G08B13/16; G08B13/1654; G08B13/1663
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
268 words
A system for detecting an intrusion into a surveillance area resulting in a change in the noise characteristic within the area from ambient type noise to a composite of ambient type noise and cultural type noise, causing a substantial shift in the noise frequency spectrum, said system comprising: a. transducer means for picking up vibrations caused by ambient and cultural noise events in the area; b. means coupled to receive output from the transducer means for converting said picked up vibrations into input signals representative of the momentary dominant frequencies of the noise events; c. long-term memory means coupled to said converting means and operative to store and average over a relatively longer period of time a level representative of the average frequency of said input signals over that period; d. short-term memory means coupled to said converting means and operative to store and average over a relatively shorter period of time a level representative of the average frequency of the most recent of said input signals; e. means for indicating an intrusion; f. means connected between said memory means and said indicating means for comparing said long-term and said short-term memory levels, and responsive to a predetermined criterion of comparison and to the results of said comparison to actuate said intrusion indicating means; g. AGC amplifier means connecting said transducer means to said converting means and operative to develop an AGC level proportional to the level of the noise events; and h. means responsive to said AGC level to block actuation of said intrusion indicating means upon substantial failure of the input noise from said transducer means.
Claim 2
Independent Claim
268 words
A system for detecting an intrusion into a surveillance area resulting in a change in the noise characteristic within the area from ambient type noise to a composite of ambient type noise and cultural type noise, causing a substantial shift in the noise frequency spectrum, said system comprising: a. transducer means for picking up vibrations caused by ambient and cultural noise events in the area; b. means coupled to receive output from the transducer means for converting said picked up vibrations into input signals representative of the momentary dominant frequencies of the noise events; c. long-term memory means coupled to said converting means and operative to store and average over a relatively longer period of time a level representative of the average frequency of said input signals over that period; d. short-term memory means coupled to said converting means and operative to store and average over a relatively shorter period of time a level representative of the average frequency of the most recent of said input signals; e. means for indicating an intrusion; f. means connected between said memory means and said indicating means for comparing said long-term and said short-term memory levels, and responsive to a predetermined criterion of comparison and to the results of said comparison to actuate said intrusion indicating means; g. AGC amplifier means connecting said transducer means to said converting means and operative to develop an AGC level proportional to the level of the noise events; and h. means responsive to said AGC level to block actuation of said intrusion indicating means upon substantial failure of the input noise from said transducer means.
Claim 3
Dependent Claim
117 words
In a system as set forth in claim 1, said converting means comprising means for converting the noise events into a voltage signal whose amplitude varies as the frequency thereof; and said memory means each comprising an averaging voltage-storage circuit each connected to receive said voltage signal and respectively having longer and shorter time constants, and said comparing means comprising a voltage comparison circuit connected to said memory means and operative to compare the voltage levels stored therein, and said comparison circuit being operative as long as said AGC level shows no failure of input noise to deliver an actuAting signal to said intrusion indicating means when the ratio of said levels changes beyond a preset criterion.
Claim 4
Dependent Claim
43 words
In a system as set forth in claim 2, means responsive to the AGC level in said amplifier means and operative upon substantial failure of input noise from the transducer means to block input of said voltage signal into said long-term memory means.
Claim 5
Dependent Claim
42 words
In a system as set forth in claim 3, said means for blocking said voltage signal further including means responsive to the delivery of an actuating signal to said intrusion indicating means for blocking said voltage signal to said long-term memory means.
Claim 6
Independent Claim
325 words
A system for detecting an intrusion into a surveillance area resulting in a change in the noise characteristic within the area from ambient type noise to a composite of ambient type noise and cultural type noise, causing a substantial shift in the noise frequency spectrum, said system comprising: a. transducer means for picking up vibrations caused by ambient and cultural noise events in the area; b. means coupled to the transducer means for converting said picked up vibrations into input signals representative of their momentary dominant frequencies, said converting means converting the noise events into pulse signals; c. long-term memory means coupled to said converting means and operative to store and average over a relatively longer period of time a level representative of the average frequency of said pulse signals over that period; d. short-term memory means coupled to said converting means and operative to store and average over a relatively shorter period of time a level representative of the average frequency of the most recent of said pulse signals, said memory means each comprising a counter operative to accumulate a digital count level; e. a source of clock pulses scaled to count pulses at a higher rate into the short-term memory counter and at a relatively lower rate into the long-term memory counter; f. means responsive to said pulse signals for scaling them according to the same ratio as said lower and higher pulse rates to provide two series of reset pulses, the less frequent reset pulses being connected to reset said long-term memory counter and the more frequent reset pulses being connected to reset said short-term memory counter; g. means for indicating an intrusion; h. means connected between said memory means and said indicating means for comparing said long-term and said short-term memory levels, said comparing means comprising means for detecting coincidence of the digital count levels in the counters and responsive thereto to deliver an actuating signal to said intrusion indicating means.
Claim 7
Independent Claim
325 words
A system for detecting an intrusion into a surveillance area resulting in a change in the noise characteristic within the area from ambient type noise to a composite of ambient type noise and cultural type noise, causing a substantial shift in the noise frequency spectrum, said system comprising: a. transducer means for picking up vibrations caused by ambient and cultural noise events in the area; b. means coupled to the transducer means for converting said picked up vibrations into input signals representative of their momentary dominant frequencies, said converting means converting the noise events into pulse signals; c. long-term memory means coupled to said converting means and operative to store and average over a relatively longer period of time a level representative of the average frequency of said pulse signals over that period; d. short-term memory means coupled to said converting means and operative to store and average over a relatively shorter period of time a level representative of the average frequency of the most recent of said pulse signals, said memory means each comprising a counter operative to accumulate a digital count level; e. a source of clock pulses scaled to count pulses at a higher rate into the short-term memory counter and at a relatively lower rate into the long-term memory counter; f. means responsive to said pulse signals for scaling them according to the same ratio as said lower and higher pulse rates to provide two series of reset pulses, the less frequent reset pulses being connected to reset said long-term memory counter and the more frequent reset pulses being connected to reset said short-term memory counter; g. means for indicating an intrusion; h. means connected between said memory means and said indicating means for comparing said long-term and said short-term memory levels, said comparing means comprising means for detecting coincidence of the digital count levels in the counters and responsive thereto to deliver an actuating signal to said intrusion indicating means.
Claim 8
Dependent Claim
206 words
A digital system for detecting an intrusion into a surveillance area resulting in a change in the noise characteristics within the area from ambient type noise to a composite of ambient type noise and cultural type noise causing a substantial shift in the noise frequency spectrum, said system comprising: a. transducer means for picking up the ambient and cultural noise frequencies; b. a source of pulses; c. a long-term counter means, a short-term accumulator means, and pulse rate scaler means operative to supply pulses to the long-term counter means at a first slower rate and pulses to the short-term accumulator at a second faster rate; d. means for converting the output of said transducer means into impulses representing zero-axis crossings and for scaling said crossing impulses to provide two different trains of reset outputs whose relative recurrence rates are in the same ratio as said faster and slower pulse rates; e. means for periodically resetting said long-term counter means using the less frequent reset outputs and for resetting said short-term accumulator means using the more frequent reset outputs; f. means for comparing the counts in said counter means and said accumulator means and for delivering a coincidence signal indicating an intrusion when the counts reach coincideNce.
Claim 9
Dependent Claim
206 words
A digital system for detecting an intrusion into a surveillance area resulting in a change in the noise characteristics within the area from ambient type noise to a composite of ambient type noise and cultural type noise causing a substantial shift in the noise frequency spectrum, said system comprising: a. transducer means for picking up the ambient and cultural noise frequencies; b. a source of pulses; c. a long-term counter means, a short-term accumulator means, and pulse rate scaler means operative to supply pulses to the long-term counter means at a first slower rate and pulses to the short-term accumulator at a second faster rate; d. means for converting the output of said transducer means into impulses representing zero-axis crossings and for scaling said crossing impulses to provide two different trains of reset outputs whose relative recurrence rates are in the same ratio as said faster and slower pulse rates; e. means for periodically resetting said long-term counter means using the less frequent reset outputs and for resetting said short-term accumulator means using the more frequent reset outputs; f. means for comparing the counts in said counter means and said accumulator means and for delivering a coincidence signal indicating an intrusion when the counts reach coincideNce.
Claim 10
Dependent Claim
78 words
In a system as set forth in claim 6, memory means interposed between said long-term counter means and said comparing means, transfer means for setting into the memory means a new count from the counter means just before the latter is reset, and means for inhibiting said transfer means from updating the count in the memory means when an intrusion detection signal has been delivered from the comparing means since the last time the counter means was reset.
Claim 11
Dependent Claim
69 words
In a system as set forth in claim 7, amplifier means coupled to the transducer means, AGC means in the amplifier means responsive to the level of the signal therein; and means coupled to the AGC means and connected to inhibit said transfer means whenever the level of the AGC indicates substantial loss of output noise from the transducer means since the last time the counter means was reset.
Claim 12
Dependent Claim
127 words
In a system as set forth in claim 6, said system being responsive to a decrease in the frequency of the noise picked up by the transducer means as a result of an intrusion whereby there are fewer zero-axis crossings and less frequent reset outputs, and said system further comprising means responsive to a first coincidence signal to increase the rate of said fast rate pulses and to supply pulses to the short-term accumulator means at said increased rate; means responsive to a second coincidence signal at the increased rate to deliver an alarm signal; and means to disable the alarm signal delivering means and return the accumulator pulse rate to the said fast rate when no coincidence signal is detected while counting at the increased rate.
Claim 13
Dependent Claim
77 words
In a system as set forth in claim 9, memory means interposed between said long-term counter means and said comparing means, transfer means for setting into the memory means a new count from the counter means just before the latter is reset, and means for inhibiting said transfer means from updating the count in the memory means when an alarm signal has been delivered from the comparing means since the last time the counter means was reset.
Claim 14
Dependent Claim
69 words
In a system as set forth in claim 10, amplifier means coupled to the transducer means, AGC means in the amplifier means responsive to the level of the signal therein; and means coupled to the AGC means and connected to inhibit said transfer means whenever the level of the AGC indicates substantial loss of output noise from the transducer means since the last time the counter means was reset.
Claim 15
Dependent Claim
72 words
In a system as set forth in claim 9, alarm means for warning of intrusions; means for counting successive coincidence signals in an effort to reach a predetermined number thereof and connected to actuate said alarm means upon reaching that number; and means for resetting said alarm signal counting means when the accumulator means is reset before its count reaches coincidence with the memory means count as determined by the comparing means.
Claim 16
Dependent Claim
23 words
In a system as set forth in claim 6, said transducer and converting means comprising a geophone connected to drive a signal-squaring amplifier.
Claim 17
Dependent Claim
178 words
An intrusion detector system, comprising: a. transducer means for detecting noise including ambient noise and intrusion-created noise where the frequency of the latter is lower than the former so that the number of zero-axis crossings of the transducer output decreases during an intrusion; b. means for counting pulses at a first slower rate into a counter and for resetting the counter at infrequent intervals whenever a certain number of zero-axis crossings have occurred, thereby to represent as a number in the counter the average frequency of noise as averaged over said long-term interval; c. means for counting pulses at a second faster rate into an accumulator and for resetting the accumulator at more frequent intervals whenever a proportionately smaller number of zero-axis crossings have occurred, thereby to represent as a number in the accumulator the short-term frequency of recently detected noise; and d. meAns for comparing the short-term count in the accumulator with the long-term count in the counter to detect a change which lowers the rate of zero-axis crossings of the noise frequency and indicates an intrusion.
Claim 18
Dependent Claim
178 words
An intrusion detector system, comprising: a. transducer means for detecting noise including ambient noise and intrusion-created noise where the frequency of the latter is lower than the former so that the number of zero-axis crossings of the transducer output decreases during an intrusion; b. means for counting pulses at a first slower rate into a counter and for resetting the counter at infrequent intervals whenever a certain number of zero-axis crossings have occurred, thereby to represent as a number in the counter the average frequency of noise as averaged over said long-term interval; c. means for counting pulses at a second faster rate into an accumulator and for resetting the accumulator at more frequent intervals whenever a proportionately smaller number of zero-axis crossings have occurred, thereby to represent as a number in the accumulator the short-term frequency of recently detected noise; and d. meAns for comparing the short-term count in the accumulator with the long-term count in the counter to detect a change which lowers the rate of zero-axis crossings of the noise frequency and indicates an intrusion.
Claim 19
Dependent Claim
79 words
In an intrusion detector as set forth in claim 14, a memory means interposed between the counter and the comparing means; means for updating the count in the memory means by setting into it a new count from the counter just before the latter is reset; and means for controlling the updating means to set a new count into the memory means only if no intrusion was indicated during the counting up of the counter during the past interval.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-08-22 | 1976-02-21 | 1976-08-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-22 | 1980-02-21 | 1980-08-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-22 | 1984-02-21 | 1984-08-22 | $7700.00 | Window Closed / Lapsed |