To improve prediction accuracy so as to shorten the time for acquisition of a satellite signal in computing of a predicted Doppler shift frequency during a tracking process in a GPS receiver.

A predicted Doppler shift frequency computed in a Doppler shift frequency computing unit 17 consists of a Doppler shift frequency f1 to a receiver for a satellite, a Doppler shift frequency error fvel depending on a speed of the receiver, a Doppler shift frequency error fTCXO due to a crystal oscillator error of the receiver, and a Doppler shift frequency error fsverr due to a satellite orbital information error. The Doppler shift frequency error fvel can be found by using receiver speed information received from an external apparatus 18, and the predicted Doppler shift frequency with higher precision can be found.