Research And Implementation On Tracking Loop In High Dynamic GNSS Software Receiver

Global Navigation Satellite System (GNSS) combines the traditional radio-navigation and astronomical mapping technology together to provide global, all-weather, continuous, real-time navigation services, can cover land, sea, air, space. Compare to single system such as GPS or GLONASS, GNSS has higher accuracy and better integrity. Therefore, multi-mode GNSS receivers have become an important direction of development. For high dynamic receiver, the received carrier frequency the characteristics of high Doppler frequency shift and high changing rate of Doppler frequency,so the ordinary receivers can't work correctly.On the basis of the GNSS system, working principle and signal format, this thesis focuses on the algorithm, design and implementation of the high-dynamic multi-mode tracking loop of the GNSS receiver. The main work is as follows:First, this dissertation study the GNSS receiver carrier and code tracking loop algorithms, various algorithms were simulated and compared against each other. According to the dynamic performance requirements of the project, some improvements on the algorithm were presented, such as:2-nd FLL assisted 3-rd PLL, carried tracking loop assisted code tracking loop. Meanwhile the dissertation designed a configurable multi-system receiver tracking channel, the design can be flexibly configured according to system requirements to achieve the purpose of saving hardware resources. Secondly, build a simulation platform to simulate the algorithm and receiving channels in VS2005 according to the loop design; and build the Modelsim simulation platform to simulate the configurable receiving channel structures.Finally, according to the loop design and simulation results, implement the track loop with the C and VHDL code on the DSP+FPGA platform, and test the performance with the evaluation system. The results show that the loop runs stable and meet the requirement of system designThis research is an independent project from navigation laboratory of the Beijing University of Posts and Telecommunications, aiming to complete the GNSS research's development and implementation work.