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Tamper detection mechanism

  • US 6,774,807 B1
  • Filed: 03/02/1999
  • Issued: 08/10/2004
  • Est. Priority Date: 03/02/1999
  • Status: Expired due to Fees
First Claim
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1. A system for detecting unauthorized movement of a communications/meter device, the system comprising:

  • at least one device attachment mechanism, having a selected attachment direction, that attaches a communications/meter device to a selected attachment site;

    a magnetic field source, associated with the attachment mechanism, that provides a first magnetic field with a first field direction and a second magnetic field with a second field direction when the attachment mechanism is in a first selected position and in a second selected position, respectively;

    a field-activated magnetic switch, positioned adjacent to the attachment mechanism and arranged so that, when the first magnetic field is applied to the switch, the switch is in a first switch state, and when the second magnetic field is applied to the switch, the switch is in a second switch state, distinct from the first switch state; and

    an electrical current source, connected to said field-activated magnetic switch at a first selected location, that provides a current through said switch;

    an electrical current sensor, connected to the field-activated magnetic switch at a second selected location, that senses a first level of current through the switch; and

    an alarm, coupled to the current sensor, that generates a selected alarm signal when the switch is not in the first switch state, upon the sensed level of current in the current sensor.

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