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Personnel location monitoring system and method

  • US 5,115,223 A
  • Filed: 09/20/1990
  • Issued: 05/19/1992
  • Est. Priority Date: 09/20/1990
  • Status: Expired due to Term
First Claim
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1. A personnel location monitoring system for indicating when an individual is no longer in a predetermined area and for providing an indication of the direction to the individual, the system comprising:

  • (a) a band adapted to be worn by an individual comprising,(1) a transmitter for periodically transmitting on a predetermined frequency a digital signal uniquely identifying the individual wearing the band,(2) a strap for carrying the transmitter and adapted to be removably affixed to the individual by encircling a part of the individual,(3) at least one tamper detector carried internally of the strap substantially along its length for indicating to the transmitter that a portion of the strap may have been removed,(4) a latch with pressure sensing means for holding the strap encircling a part of the individual when the latch is closed and for indicating to the transmitter that the latch is not applying pressure to the pressure sensing means when the latch is open; and

    (b) a monitoring/tracking unit comprising,(1) selector means for selecting one of a monitoring mode and a tracking mode, said selector means having secure means for preventing unauthorized deselection of the monitoring mode,(2) antenna means for omnidirectional and directional reception on the predetermined frequency,(3) receiver means connected to the antenna means for receiving a signal on the predetermined frequency and for indicating the signal strength thereof,(4) a comparator for comparing data in the received signal to a predetermined identifier that uniquely identifies the individual whose location is to be monitored and for providing a predetermined voltage when the data in the received signal matches the predetermined identifier,(5) a timer operably connected to the comparator that is reset by receipt of the voltage for providing an indication that the voltage has not been received for a predetermined period of time after the timer has been reset,(6) alarm means responsive to the indication that the timer has not received the voltage for a predetermined period of time for indicating that the individual may not be in the particular area,(7) means for disabling the timer when the tracking mode is selected,(8) means for providing an indication that the signal strength of the received signal exceeds a predetermined level when the tracking mode is selected.

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