Tracking Loop with Dynamic Gain Controlled DPLL in Software GPS Receiver

Tracking is an important step in the signal processing section of a GPS receiver. It detects the presence of GPS signals received by antenna and provides precise estimation of the code phase and Doppler frequency for navigation data demodulation. The main research of this paper is to design and analyze of the tracking loop algorithms of GPS software receiver. First, a software parallel correlation is presented to enhance the speed of signal processing which can reduce the execution time. A new loop controller design method for DPLL is developed. The DPLL with gear-shifting gain control technique is implemented such that a better performance of transient response is accomplished. It is shown that our algorithm can save 23.9% of settling time in comparison with the conventional DPLL.