Acoustic emission intrusion detector

Patent · Mon Dec 31 23:00:00 EST 1979

OSTI ID:863549

Carver, Donald W ^[1]; Whittaker, Jerry W ^[1]

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1. Knoxville, TN

An intrusion detector is provided for detecting a forcible entry into a secured structure while minimizing false alarms. The detector uses a piezoelectric crystal transducer to sense acoustic emissions. The transducer output is amplified by a selectable gain amplifier to control the sensitivity. The rectified output of the amplifier is applied to a Schmitt trigger circuit having a preselected threshold level to provide amplitude discrimination. Timing circuitry is provided which is activated by successive pulses from the Schmitt trigger which lie within a selected time frame for frequency discrimination. Detected signals having proper amplitude and frequency trigger an alarm within the first complete cycle time of a detected acoustical disturbance signal.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN
• DOE Contract Number: W-7405-ENG-26
• Assignee: United States of America as represented by United States (Washington, DC)
• Patent Number(s): US 4196423
• OSTI ID: 863549
• Country of Publication: United States
• Language: English

Related Subjects

/340/307/324/
acoustic
acoustic emission
acoustic emissions
acoustical
activated
alarm
alarms
amplified
amplifier
amplitude
applied
circuit
circuitry
complete
complete cycle
control
crystal
cycle
cycle time
detected
detected signal
detected signals
detecting
detector
discrimination
disturbance
emission
emissions
entry
false
false alarms
forcible
frame
frequency
intrusion
intrusion detector
level
lie
minimizing
output
piezoelectric
piezoelectric crystal
preselected
proper
provide
provided
pulses
rectified
schmitt
secured
selectable
selected
selected threshold
selected time
sense
sensitivity
signal
signals
structure
successive
successive pulses
threshold
threshold level
time
time frame
timing
timing circuit
transducer
trigger
trigger circuit