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Dual alarm apparatus for monitoring of persons under house arrest

  • US 5,448,221 A
  • Filed: 07/29/1993
  • Issued: 09/05/1995
  • Est. Priority Date: 07/29/1993
  • Status: Expired due to Fees
First Claim
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1. A monitoring system comprising:

  • a base unit including a transmitter coupled to a base control unit, range measurement means coupled to the base control unit for generating range data, and remote communication means coupled to the base control unit for communicating with a monitoring service; and

    at least one portable remote device including a receiver, a transmitter, and an alarm unit, each of which is coupled to a control unit;

    wherein the base unit periodically transmits a signal to the portable remote device and the portable remote device transmits a signal back to the base unit;

    wherein the range measurement means generates range data based on a time difference between the signal transmitted from the base unit and receipt of the signal transmitted from the remote device;

    wherein the base control unit compares the range data to a predetermined permitted range and generates an alarm signal if the range data exceeds the predetermined range;

    wherein the base unit transmits the alarm signal to the remote device and the control unit of the remote device activates the alarm unit to generate an audible out-of-range signal in response to the alarm signal; and

    wherein the base unit transmits a violation signal to the remote device if the range data exceeds the predetermined range for a preset time interval, and the control unit of the remote device activates the alarm unit to generate an audible violator signal in response to the violation signal.

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