Costas Tracking Loop Based Cross-Data Bit Coherent Integration

In order to solve the integration energy loss problem in GNSS receiver caused by the reversal of cross-data bit, this paper proposed one improved Costas loop which could carry out cross-data bit coherent integration. The coherent integration scheme of proposed loop was divided into two steps, firstly, a short coherent integration over one code period was performed, secondly, another long coherent integration cross-data bit was performed based on the short coherent integration result and its sign. A theoretical analysis to proposed Costas loop was made in the paper. A simulation compare between proposed loop and classic Costas loop was made. Analysis and simulation results showed that, proposed loop could improve carrier tracking precision at weak signal by increasing coherent integration time without navigation data bit limitation.