Abstract:

To solve the acquisition problem of global position system (GPS) signals in weak signal environment, a new double block zero padding (DBZP) differential coherent acquisition algorithm is proposed. Integrating fast Fourier transform (FFT), DBZP, differential coherent methods with frequency error correction technology organically, the algorithm effectively reduces chip rate variation caused by large Doppler frequency shift and the correlational power loss as a consequence in the course of computing FFT. Meanwhile the power loss caused by the Doppler frequency error is also weakened. Experiment results show that the acquisition system has a much higher performance using the proposed algorithm, and it can be seen that the sensitivity is improved about 2.8 dB compared with the direct FFT acquisition algorithm in simulated data sets. The standard deviation of the Doppler frequency is less than 20 Hz when the integration time and carrier-to-noise ratio are given, and the signal-to-noise ratio （SNR） is improved about 3 dB compared with the direct FFT acquisition algorithm in experimental data sets.