A new signal acquisition algorithm in GNSS software receiver

A new signal acquisition algorithm is proposed based on the principle that the circular shifting operation in frequency-domain is equal to the carrier wipe-off operation in time-domain. The repeating operations of FFT and carrier wipe-off in each carrier Doppler searching bin could be replaced by the circular shifting of the spectrum sequence of the incoming signal, thus the FFT of the incoming signal is implemented only once during the 2-dimension search of code-phase and carrier Doppler. With no degradation in probability and accuracy of acquisition, the new algorithm can significantly reduce the acquisition time compared with the traditional one. This algorithm has been implemented in the GNSS software receiver to acquire the raw GPS signal, experiment results show that the proposed algorithm can acquiste GPS signal correctly while reducing acquisition time by 50%.