Research And Implementation Of GNSS Satellite Signal Simulation System Based On VPX

With the continuous improvement of the Global Navigation Satellite System(GNSS),the rapid development of satellite navigation and positioning technology is correspondingly promoted.At present,the satellite positioning solution of the navigation terminal also shows a trend of developing towards multi-system and multi-band GNSS satellite signal combined navigation,so as to obtain high-precision and high-quality location services.Therefore,in order to meet the testing requirements in the research process of the navigation terminal and the application in other satellite navigation scenarios,this paper designs a data processing platform that can realize multi-system and multi-band GNSS satellite signal simulation based on the VPX bus architecture.At the same time,the simulation method of GNSS satellite signal of this platform is studied and realized.The main research results are as follows:1.Studied the signal system of GPS and GLONASS in depth,grasped the principle of signal generation,combined with the design requirements of multi-system and multi-band GNSS satellite signal simulation system,proposed a GNSS satellite signal simulation system design scheme based on VPX bus architecture.2.Based on the VPX bus architecture standard and design scheme,the design of the VPX interconnect backplane,the VPX signal output control mainboard and the VPX signal generate subboard has been completed.The VPX interconnect backplane is mainly used to provide power,clock and data exchange functions for VPX signal generate subboard and VPX signal output control mainboard;The VPX signal output control mainboard adopts the design structure of FPGA + high-precision D/A module,which is mainly used to complete the interaction of GNSS signal simulation parameters between the host computer and the VPX signal generation daughter board,and control the synchronization trigger and reset of VPX signal generation subboard,perform synchronous processing of GNSS digital intermediate frequency satellite data,and complete the digital/analog conversion of GNSS digital IF satellite signal;The VPX signals generate subboard adopts the design structure of DSP+FPGA,which is mainly used to carry the operation of the GNSS satellite signal simulation algorithm and the modulation and generation of the multi-channel GNSS digital IF satellite signal.3.Conduct in-depth research on signal integrity and power integrity issues in highspeed circuit design,and the causes of signal reflection and crosstalk in signal integrity design,as well as IR drop and power supply noise drop in power integrity design are analyzed.At the same time,the corresponding solutions to these key problems are given,and combined with the specific design examples in this design for illustration and simulation verification,completed the signal integrity and power integrity design of VPX data processing platform.4.Based on the VPX data processing platform,the design and implementation of the GNSS satellite signal simulation system are completed,the design process and implementation method of GNSS satellite signal generation are given,and the key modules are verified by simulation.Finally,the system is tested and analyzed from the characteristics of intermediate frequency signal and positioning performance,and it is verified that the simulated GPS L1 and GLONASS L1 satellite signals of the system can make the receiver perform correct positioning calculation,and have good positioning accuracy and dynamic characteristics.