Patent ID: 7317418

Claim:
A global positioning system (GPS) satellite signal receiver, comprising: a signal processing circuit for acquiring and tracking a plurality of GPS satellite signals; a power control circuit coupled to the signal processing circuit, the power control circuit enabling power to be supplied to the signal processing circuit during an active state, and suspending power from being supplied to the signal processing circuit during a sleep state; a timer for keeping track of a duration of the sleep state; a temperature-compensated oscillator for generating a clock signal; and a controller, coupled to the timer and receiving the clock signal, which (i) tracks a GPS time based upon the received clock signal to provide a tracked GPS time; (ii) upon the signal processing circuit entering the active state from the sleep state, determines whether or not the duration of the sleep state exceeds a threshold value; (iii) if duration of the sleep state does not exceed the threshold value, performs a position fix using the GPS satellite signals acquired and the tracked GPS time; and (iv) if the duration of the sleep state exceeds the threshold, the controller, performs a position fix without relying on the tracked GPS time.