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Field unit for use in a GPS system

  • US 6,531,982 B1
  • Filed: 09/30/1997
  • Issued: 03/11/2003
  • Est. Priority Date: 09/30/1997
  • Status: Expired due to Term
First Claim
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1. A system for monitoring a field unit associated with a predetermined object, comprising:

  • a GPS reception unit configured to receive position information from a plurality of GPS satellites;

    an environmental circuit configured to sense environmental conditions and produce an environmental signal representative of the environmental conditions a transmitter configured to transmit the position information and the environmental signal via radio frequency communications upon interrogation from a base station;

    said transmitter is further configured to initiate communications with a base station and transmit the position information and the environmental signal via cellular communications where said field unit is outside a predetermined range from said base station;

    the environmental circuit comprises a memory storage for storing object information pertaining to the object;

    the environmental signal further comprises data representing the object information stored in the memory storage; and

    wherein the reception unit, the environmental circuit and the transmitter reside in the field unit.

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