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Title: Acoustic emission intrusion detector

Abstract

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.

Inventors:
 [1];  [1]
  1. (Knoxville, TN)
Issue Date:
Research Org.:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN
OSTI Identifier:
863549
Patent Number(s):
4196423
Assignee:
United States of America as represented by United States (Washington, DC) ORNL
DOE Contract Number:  
W-7405-ENG-26
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
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/

Citation Formats

Carver, Donald W., and Whittaker, Jerry W. Acoustic emission intrusion detector. United States: N. p., 1980. Web.
Carver, Donald W., & Whittaker, Jerry W. Acoustic emission intrusion detector. United States.
Carver, Donald W., and Whittaker, Jerry W. Tue . "Acoustic emission intrusion detector". United States. https://www.osti.gov/servlets/purl/863549.
@article{osti_863549,
title = {Acoustic emission intrusion detector},
author = {Carver, Donald W. and Whittaker, Jerry W.},
abstractNote = {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.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1980},
month = {1}
}

Patent:

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