Fast fine acquisition algorithm of GPS receiver aided by INS information

Acquisition time of global position system (GPS) receiver, which is the main factor contributes to time to first fix (TTFF), can be shortened by estimating the Doppler frequency shift through external inertial navigation system (INS) information and almanac data and reducing the searching area. The traditional fast acquisition is analyzed, the fast acquisition of the GPS receiver aided is presented by INS information, and the signal is fine captured by spectrum zooming. Then the algorithm is simulated by sampled GPS intermediate frequency (IF) signal and the result verifies that this acquisition can dramatically improve the capability of GPS receiver and reduce its acquisition time.