Hardware Design And Implementation Of Multi-system Multi-frequency Satellite Navigation Simulator

With the development of communication technology,the Global Navigation Satellite System(GNSS)has played an important role in various fields and has become an important indicator for measuring science and technology.Very important.The multi-system multifrequency satellite navigation simulator can provide position coordinates at any time,and can also generate high-precision and high-dynamic simulated satellite signals in various complex environments.At the same time,it can provide some reference for the construction of Beidou global networking in China effect.This paper focuses on the design and implementation of a multi-system multi-frequency satellite navigation simulator.First,by analyzing the signal systems of the four satellite navigation systems GPS,BDS,GLONASS and Galileo,the direct frequency of the multisystem multi-frequency satellite navigation simulator is studied in depth Key technologies such as synthesis,spread spectrum communication,Doppler algorithm simulation principle,navigation system time synchronization,and data synchronization and transmission between baseband boards.A data synchronization and transmission technology between baseband boards is proposed,which not only ensures stable communication between baseband boards,but also solves the problem of insufficient satellite signal resources on a single baseband board.Next,design the overall scheme of the multi-system multi-frequency satellite navigation simulator,introduce the key circuit design of the baseband signal board,introduce the simulator system time reference and RTC timing control,digital intermediate frequency signal generation and EMIF communication module in FPGA software design in detail Design and simulate the various modules of the system;Finally,the DSP operation process is elaborated,in which the real-time calculation of satellite position,the real-time judgment of visible satellites and the real-time calculation of pseudorange are introduced in detail.Finally,this paper implements a multi-system multi-frequency satellite navigation simulator on two baseband signal boards of DSP + FPGA architecture.This system tests the intermediate frequency signals of each system through a spectrum analyzer,and then uses Hexinxingtong's commercial receiver UM220 to perform functional and stability tests on the designed system,and then uses the positioning results to analyze and verify the correctness of the system.Finally,the BDS B1 C frequency point and Galileo E1 frequency point are captured and tested to verify the correctness of these two frequency points.