Importance

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Abstract

Reserve power is provided in a portable cellular transceiver comprising a Global Positioning System (GPS) receiver by monitoring a power level of a battery of the portable cellular transceiver using a power detection circuit. A comparator circuit determines whether the power level of the battery is greater than a predetermined threshold. Based on the available power level, a power control circuit automatically places the transceiver into at least one low power mode when the power level reaches a corresponding threshold level. The low power mode selectively powers down circuitry of the portable cellular transceiver. The corresponding threshold level reserves power for an emergency telephone call. Power is provided to the circuitry of the portable cellular transceiver when the available power level is greater than the predetermined threshold. The reserve power provides power for the activation of the portable cellular transceiver, establishment of a call between the portable cellular transceiver and a cellular base station, transfer of GPS satellite acquisition aiding information to the portable cellular transceiver, receipt of GPS satellite information, communication of GPS satellite information to the cellular base station, and determination of a position of the portable cellular transceiver. The emergency telephone call may be a single button enhanced 911 call.

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First Claim