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Intrusion alarm sensing unit

  • US 5,216,410 A
  • Filed: 11/16/1990
  • Issued: 06/01/1993
  • Est. Priority Date: 11/16/1990
  • Status: Expired due to Term
First Claim
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1. In an intrusion detection system having at least one sensing unit, each sensing unit comprising at least two motion sensors with each sensor, when activated, producing an unconfirmed event signal indicating detection of motion, and logic processing means for monitoring said unconfirmed even signals of said sensors and producing an alarm signal if both sensors produce unconfirmed event signals within a predetermined time of each other thus confirming the event signals;

  • said logic processing means processing said unconfirmed event signals to determine a possible malfunction of the sensing unit and producing a trouble signal based on the processed unconfirmed event signals received, said logic processing means including selectable means which when selected causes said logic processing means to process further unconfirmed event signals received after a trouble signal has been produced to produce an alarm signal when said further unconfirmed event signals satisfy a predetermined criteria whereby an alarm signal can be produced based upon the receipt of unconfirmed event signals in addition to the alarm signal being produced upon receive of confirming event signals.

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