Research And Design On The High Dynamic Satellite Signal Simulator

GNSS satellite signal simulator can accurately simulate real-time satellite signals received by target receivers in accordance with the signal structure, trajectory of the receiver and environmental parameters defined by users, which is essential testing and measuring instrument for the research of the high dynamic GNSS receivers. It is used to measure and verify the ability of acquisition and tracking and positioning accuracy for the GNSS receiver. And it is of great signficance for the development of military and civil application.The research of this thesis focuses mainly on the technology of digital signal processing, the method of signal generation and the design technology about GNSS satellite signal simulator. This paper includes the following aspects.Above all, this paper introduces the structure and the main electrical characteristics of satellite signals of GNSS with the different modulation methods. Corresponding mathematical models are also given, and construction of these models in the simulator is analyzed.Secondly, the system structure of the high dynamic GNSS satellite signal simulator , which bases on signal structures and the pseudo-range calculation equations, combines DSP with FPGA on the overall design. It is mainly composed of IPC simulation software, IF signal generator, D/A module and RF module. The design of DSP communication, DSP software and FPGA software is elaborated, and the interface design between the DSP and the FPGA is briefly introduced.Thirdly, this paper introduces coordinate system of GNSS, and further discuss the calculation about real-time position and transmission errors of satellites. A variety of factors, which caused by the pseudo-range calculation error in the signal processing in the DSP platform, are analyzed as the focus. According to the pseudo-range calculation error, the error simulation models of ionospheric delay and tropospheric delay are established.Finally, testing methods and results about error accuracy and quality of the RF single in GNSS satellite signal simulator are given. The results show that the quality of the RF signal meets the basic indicators. The receivers can real-time position by receiving the simulated signal. The simulator has good stability and good performance.