Algorithm Study And Application For Baseband GNSS Signals

With the continual progress of satellite navigation technology, using GNSS in position, navigation and timing services has become possible. Nowadays, GNSS has become the significant space and information infrastructure of each major country, also reflected the modern country’s status and comprehensive national power. With the popularity of intelligent devices, using GNSS to positioning and navigation also begin to move into people’s daily life. It also provides a powerful impetus for the further development of GNSS.Firstly, we studied and researched the positioning principle of GNSS and receiver of GNSS. Then, we carefully researched and experimented GNSS receiver’s signal processing of the digital intermediate frequency signal and optimized a part of algorithm. Finally, we designed a GNSS software receiver based on ARM embedded Linux platform. In this paper, we optimized the Parallel Code Phase Search Acquisition algorithm and proposed the Multiple Resampling Acquisition algorithm. This algorithm resamples the digital intermediate frequency signal for many times and then resampling signal is used to capture the GNSS signals. The entire process of acquisition under control adaptively by control unit and this algorithm can capture strong and weak signal separately. At the same time, we also analyzed computational complexity of various acquisition algorithms and compared the computational complexity of the Parallel Code Phase Search Acquisition algorithm and the Multiple Resampling Acquisition algorithm in theory and experiment. Experiments show that this algorithm not only can achieve quite acquisition results with other algorithm but also reduce the signal processing points, thus reducing the computational complexity of acquisition and speeding up the acquisition of GNSS signal. We also studied the signal tracking section of the digital intermediate frequency signal processing and introduced the DLL, FLL and PLL of tracking section and simulated the three loops with real data.Through the study and research of GNSS positioning and navigation principle and receiver structure, we designed a software receiver. All code of the software receiver was written by C language and runs on a ARM board with embedded Linux system. Real GNSS digital intermediate frequency signals are used to positioning experiments, and experiments prove that the software receiver can achieve positioning function successfully.