| 摘要 |
A global positioning system (GPS) receiver and a method having a fast time to first fix (TTFF) using GPS signal Doppler frequency shifts for correcting the local clock time and using information for an expected GPS message for synchronizing the corrected local clock time to GPS time. The GPS receiver includes radio frequency (RF) circuitry for receiving and downconverting a spread spectrum GPS satellite signal, a correlator for despreading the downconverted GPS signal and providing a GPS bit stream, a clock for providing a local time, and a processor including an executable code. The executable code includes a Doppler correction code for improving the accuracy of the local time by comparing a measured and a calculated Doppler frequency shift for the GPS satellite signal from three or more GPS satellites, and a GPS synchronization code for synchronizing the local time so that the timing of a replica bit stream based upon information for an expected GPS message matches the timing a GPS bit stream received in the GPS satellite signal.
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