A fast capture structure for dichotomous DMF pseudocode based on DSP Builder

Abstract

To address the problem of capturing correlation peak amplitude decay and difficulty in determining the capture threshold when the demodulated signal is synchronously captured by DMF (all-digital matched filter) under the influence of Doppler frequency bias, the dichotomous DMF method is proposed: the pseudo-random sequence is segmented before and after to reduce the integration time of correlation operation, and then reduce the loss of normalized correlation peak under the influence of frequency bias integration decay. Matlab platform simulation verifies the effect of correlation length on the loss of correlation peaks under the frequency bias scenario, and the experimental results show that the dichotomous DMF method is less sensitive to the Doppler frequency bias than the DMF method. In order to reduce the hardware resource overhead of the pseudocode phase search module and to ensure a certain search efficiency, a serial-parallel structure with serial data transmission and parallel operation is adopted, which can search multiple code elements at a time for phase deviation in the pseudocode phase search and improve the capture efficiency.