Seismic-acoustic detection device
First Claim
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1. A detection logic system for providing a logic signal when a predetermined number of pulses in an input signal are received during a preselected first time interval beginning with the first pulse, comprising:
- input gate means adapted to receive the input signal for producing an inverted replica signal thereof;
first timing means connected to receive the replica signal for providing a reset signal at the end of the first interval;
counter means coupled to receive the replica and reset signals for producing a first gating signal upon receiving one less than the predetermined number of replica signal pulses, said counter means resetting upon receiving the reset signal;
second timing means operatively connected to receive the replica signal for providing a second gating signal during a preselected second time interval shorter than the first interval; and
output gate means connected to receive the replica and gating signals for providing the logic signal upon coincidence of the received signals.
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Abstract
A detection system for indicating the presence of motorized equipment in aesignated area having an acoustic sensor, a seismic sensor and an acoustic signal transmitter. The seismic sensor output, processed to discriminate against vibrations of short duration, is fed, along with the acoustic sensor output, to an "ANDing" circuit which gates the acoustic transmitter. The acoustic sensor output is passed to the transmitter only during coincidence of seismic and acoustic detection.
11 Citations
7 Claims
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1. A detection logic system for providing a logic signal when a predetermined number of pulses in an input signal are received during a preselected first time interval beginning with the first pulse, comprising:
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input gate means adapted to receive the input signal for producing an inverted replica signal thereof; first timing means connected to receive the replica signal for providing a reset signal at the end of the first interval; counter means coupled to receive the replica and reset signals for producing a first gating signal upon receiving one less than the predetermined number of replica signal pulses, said counter means resetting upon receiving the reset signal; second timing means operatively connected to receive the replica signal for providing a second gating signal during a preselected second time interval shorter than the first interval; and output gate means connected to receive the replica and gating signals for providing the logic signal upon coincidence of the received signals. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification