Research And Realization On Acquisition Algorithms Of GNSS BOC Long-code Signal

With the impelling of the GPS modernization, the BOC modulation is becoming more and more widely used in both military and civil area. It has become a hot topic and hard work to study the long code acquisition under BOC modulation in the navigation signal processing field. This article gives an in-depth research on the direct capture methods for the long period code of the GNSS system, on this basis, for the characteristics of the M code signal of GPS system, we propose an algorithm which is suitable for M code signal directly acquisition, and the performance of the algorithm is analyzed. Finally, the key steps of the algorithm are achieved by the use of DSP. Specifically, the work will focus on the following aspects:First, the long period codes of the GNSS and the direct acquisition theory for them are studied, and simulation and analysis of these methods are made. And then, the problems which is brought by the power spectral density and the autocorrelation function of the BOC signal are analyzed. We also study the existing two kinds of BOC signal capture algorithms and the property of the sub-carrier of the BOC signal spectrum. Add the right side spectrum to the left one with its phase turning over by 90 degree, on this basis, a new algorithm for BOC signal acquisition is given. It has a bigger ratio peak and a smaller calculation compared to the traditional methods.It is a middle course between the performance of the algorithm and the calculation, this makes it becomes a good choice to solve the acquisition problems of the long period code.This article also gives a study of the statistical properties of the signal capture process, including the capture and analysis of probability and the selection of accumulation approach.Then, on the basis of the aforementioned studies, we designed a capture programs for the GPS M-code signal, including its pseudocode phase and Doppler search. We make the partition correlation theory and the new BOC signal algorithm without ambiguity together to get the integrated project of the M-code signal acquisition. Based on this analysis, the performance and the realizability of the algorithm are also analyzed.Finally, the new M-code acquisition algorithm is achieved by the use of DSP. With the use of TI’s high performance TMS320C6455 DSP devices as the core hardware platform, the verification of the algorithm is completed. Compared to the previous solution based on FPGA, the DSP-based achievement helps reduce the power consumption and good to the upgrade of the system software. It also plays an important role to the miniaturization and low power consumption of the designment of the entire receiver. Finally, according to the algorithm processes, to maximize performance under the premise of mutual cooperation CCSLink with CCS, the functional verification of the algorithm is completed, and the program has been optimized to achieve better results.