Design And Implementation Of Vector Tracking Loop For Satellite Navigation Receiver

With the rapid development of the city,the traditional satellite navigation receiver is facing severe challenges in the increasingly complex urban environment.As for the satellite navigation receiver between the high buildings in the city,due to the shelter of tall buildings or trees,satellite signals will be frequently blocked.The traditional receiver tracking loops cannot keep track of satellite signals while a satellite signal is blocked,and when the signal is recovered,it is necessary to re-capture again to re-track the satellite signal.And the vector tracking loop can calculate the loop parameters of the tracking channel use the signal of the unshielded satellite during the occlusion of the satellite signal,and when the signal is recovered,the tracking loop can quickly re-track the satellite signal without re-capture,thus improving the system availability.This paper mainly studies the design and implementation of vector tracking loop.This paper taking L1 carrier and C/A code signal of GPS as the research object.In this paper,firstly,the composition of GPS system and,the basic structure and signal processing flow of GPS receiver are introduced;Secondly,the tracking loop of the traditional receiver is analyzed,and the structure of the scalar carrier tracking loop and the code tracking loop,and the loop filter are discussed;Then,the basic idea of vector tracking is expounded,and a simple and easy-to-implement vector tracking loop structure is proposed based on the traditional scalar tracking loop,a centralized Kalman filter is used to centralized process the data of all channels,instead of the individual filters in each of the scalar tracking loops,and then feedback the navigation solution results to the tracking loops to control each channel,and the structure;Parameter model and signal processing flow of the vector tracking loop are analyzed;Thirdly,the tracking performance of the vector tracking loop is simulated by MATLAB software receiver,which proves that the vector tracking loop has excellent fast re-tracking performance;Finally,the realization of vector tracking loop algorithm is completed based on FPGA + DSP development platform,the scalar tracking loop and the vector tracking loop are designed on the platform at the same time,and the parameters of the vector loop are initialized by the scalar tracking result.The test results show that the designed vector tracking module can work normally and the horizontal positioning error is about 10 m,therefore,the vector tracking loop structure designed is feasible.