Research On Key Algorithms Of GNSS Software Receiver

The satellite navigation industry has been paid great attention in the world, which is a rapidly developing information industry following the Internet and Mobile Communication. As an important part of the satellite navigation industry, the GNSS software receiver technology has made a considerable progress. It breaks through the limitations of traditional receiver, such as nonfunctional, poor expansibility, taking the hardware as the core. Moreover, because of its hardware's reusability, software scalability, function configurable, platform versatility, flexibility, openness and many other advantages, the GNSS software receiver become an important development direction of the satellite navigation receiver.As the navigation and positioning system has been used more widely, the requirements for positioning accuracy are increasingly higher. Therefore, seeking for an effective and precise positioning method becomes an important direction in the software receiver research area. Taking the typical GPS system as the research object, the main study work includes the following three aspects: GPS signal acquisition, tracking algorithm; GPS positioning algorithm; design and simulation of the software receiver:1. The GPS signal acquisition and tracking algorithm study. We mainly analyze the GPS signal structure and the characteristics, complete the simulation verification of the GPS signal acquisition and tracking algorithm by choosing GPS intermediate frequency signal which obtained from intermediate frequency signal gathering, after the code synchronization, the frame synchronization and a series of processing, finally the the pseudo-range, the carrier phase and other useful information has been got and the navigation message has been demodulated.The continuous search acquisition algorithm, the frequency domain fast acquisition algorithm (FFT related acquisition algorithm) and improved batch acquisition algorithm are respectively adopted for the GPS signal acquisition. Through analysis and comparison, the advantage in computation of the FFT related acquisition algorithm has been verified by compared with continuous search acquisition algorithm; we validate that the improved batch acquisition algorithm can be used to capture more satellites and provide enough usable satellites for the carrier phase algorithm.2. The GPS positioning algorithm based on software receiver. After we have obtained the navigation message, the pseudo-range, the carrier phase and other useful information, we locate the user by using the present guidance algorithm and the carrier phase positioning algorithm, respectively. Comparing the result of two positioning algorithms, it has been proved that carrier phase positioning algorithm is effective in improving positioning accuracy.3. Design and implementation of the main function of the software receiver. The software receiver's functions include the intermediate frequency data pre-processing, the signal capture and the track demonstration, the code synchronization and the frame synchronization display, the navigation message display, the pseudo-range and the carrier phase information extraction, the satellite position display, output and comparet for the result of different positioning methods. Considering the software's practicability, we design a user-friend interface which is characterized by good interaction and easy to operate.The GPS signal acquisition, tracking algorithm, pseudo-range positioning algorithm and carrier phase positioning algorithm are analyzed, simulated and verified in this thesis. The above algorithms have been supported by experimental results. Our research has high practical value and can be as the theoretical foundation for achieving the main function of the GPS software receiver.