Improved Acquisition Algorithm for Correcting False Alarm of Doppler Shift of Spectrum Spreading Signal

Focusing on a kind of false alarm of Doppler shift in pseudo random (PN) code acquisition module of direct sequence spectrum spreading system(DSSSS) receiver, an improved code acquisition algorithm for correcting false alarm of Doppler shift is presented and analyzed. This algorithm uses the PN code phase estimation to eliminate PN code two-phase modulation effect, then gains Doppler shift estimation by fast Fourier transform(FFT), and compares the former estimation with the corresponding frequency point of the largest value in amplitude of FFT results. If there is wrong with the Doppler shift estimation, then to give the true value. The simulation results indicated that this improved method is reliable and effective.