New Acquisition Method in GPS Software Receiver with Split-Radix FFT Technique

Acquisition is the first step in the signal processing section of a Global Position System (GPS) receiver. It detects the presence of a GPS signal received by antenna and provides estimates of code phase and Doppler frequency to the tracking loops. Three acquisition methods in frequency-domain processing are compared, i.e., namely radix-2, split-radix-2/4 and split-radix 2/8 FFTs. The expectancy of the split-radix algorithm is increasing the acquisition efficiency. It is shown that the split-radix-2/8 FFT can save 25% of data loads and stores compared with split-radix-2/4 FFT. The modified Tone detector is applied to enhance the probability of detection. Finally, the acquisition functions are developed in software architecture running on PC.