Analysis and optimization of PMF-FFT acquisition algorithm for high-dynamic GPS signal

(Partial Matching Filter)PMF-(Fast Fourier Transformation)FFT algorithm has advantages in acquisition speed and hardware complexity. However in Doppler frequency acquisition there is a contradiction between acquisition accuracy and hardware complexity. In addition the range of frequency acquisition is limited. What´s worse in this limited and small range, the peak of output seriously decline with the increasing of Doppler frequency. To solve problems above, first of all this paper analyzed the source of defects, accordingly FFT was replaced by (Discrete Fourier Transformation) DFT to eliminate the contradiction between acquisition accuracy and hardware complexity. Then this paper used the known Doppler frequency got before losing track to switch the acquisition target from Doppler frequency itself to its variation during a shot time through which way the negative effects from limited acquisition range is avoided. Last this paper used a digital divider to dynamically eliminate the factor for attenuation of output peak. Theoretical analysis and simulation result showed that while keep the advantages of PMF-FFT algorithm the optimized algorithm had effectively overcame the defects sothat it will serve well in the design of receiver for high-dynamic GPS signal.