Research on High Sensitivity Acquisition Methods for the BDS B1I Signal

As the BDS B1I signal transmitted by MEO/IGSO satellites is modulated with 1 kbps Neumann-Hoffman code (NH code), the coherent integration time is limited within 1 ms, which cause difficulties to acquire weak signals. To overcome the problems brought by high bit-flipping rate of NH code, this paper conducts research to improve PMF-FFT (partial matched filter and fast Fourier transform) methods [1, 2] according to the feature of the B1I signal. Firstly, the estimation of NH code phase is done during acquisition to remove the effect of NH code and extend coherent integration time. And then incoherent integration is done to further improving the processing gain. Finally, simulations are conducted, the results show that the revised PMF-FFT methods can successfully acquire B1I signal as weak as 23 dB-Hz.