High Dynamic Spread Spectrum Signal Acquisition Algorithm based on Delay Autocorrelation

A carrier acquisition algorithm based on delay autocorrelation is proposed due to the failure of applying traditional fast Fourier transform (FFT)-based carrier acquisition method to high-dynamic spread spectrum signal acquisition with large Doppler frequency shift and large change rate. Firstly, two parameters are considered, i.e. highdynamic Doppler initial frequency shift and frequency change rate. Then, the modulation of the high-dynamic spread spectrum receiving signal by square method as well as the influence of spread spectrum code was removed. After that, the Intermediate Frequency (IF) sampling signal is correlated with its delay, and the estimations of Doppler frequency shift and its initial shift are obtained by applying the delay autocorrelation FFT on the signal to complete the compensation. The simulation results show that the proposed algorithm can not only shorten the capture time, reduce the computational cost, but also quickly complete the estimation of initial carrier Doppler frequency and its change rate. The proposed algorithm satisfies the conditions of large Doppler frequency shift and fast acquisition.