Patent ID: 7123190

Claim:
A method for faster warm-starts of a high-sensitivity navigation satellite receiver in a weak signal environment, the method comprising: during a first session with a GPS receiver, acquiring GPS satellites and producing a user position fix and solving GPS system time at a receiver millisecond interval; reading and calibrating a count relative to said receiver millisecond interval from a crystal-oscillator driven timer included in said GPS receiver; logging in a memory any count obtained from said timer and the GPS system time when the count was obtained; powering down to end said first session and powering back up to begin a second session, all the while said timer is kept alive and continues to advance its count; reading the count of said timer at a receiver millisecond interval and subtracting a last count stored in said memory in said first session to determine a turn-off period that the GPS receiver was turned-off; and adding said turn-off period to a last known GPS system time to set the receiver time.