Acoustic emission intrusion detector

Patent · Tue Jan 01 00:00:00 EST 1980

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 (United States)
• 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

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