Research And Application Of Digital Doppler Receiver System In Deep Space Exploration

Deep space exploration is a focus of the current and future development in the field of aerospace, and it is also a hot research topic in recent years. As a part of radio deep space exploration, digital receiver in deep space exploration achieves reception and processing of the spacecraft downlink signal, acquiring the frequency, amplitude and phase information of the Doppler signal. The Doppler data resolved can be applied to planetary atmospheric occultation inversion and deep space spacecraft orbit measurement.Doppler parameters are estimated by using Verilog HDL language and IP core on the digital receiver hardware platform, and the whole digital Doppler receiver is debugged and optimized to achieve its expected application.Firstly, the dissertation introduces some research background and oversea current development of the subject. Then, it has a brief introduction of the digital receiver system framework and detailed description on the basis of relevant theories. It focuses on the Doppler parameter estimation algorithms, including the phase difference method, early-phase estimation algorithm based on Rife algorithm and CZT algorithm, and compared these types of algorithms under different SNR. And it analyses and simulates the total phase algorithm of integration. Based on the theoretical algorithm, it implements chirp frequency module, dualram module, the initial phase estimation module, the magnitude estimation module and the serial module in FPGA as the core of the Doppler receiver system. The simulation for these modules in ISim and Chipscope is also done. The simulation results show that the various modules achieves the desired functional specifications. After integrating various modules into a system engineering, it optimizes FPGA resource.Finally, it carries out tests for the digital receiver. In the laboratory environment, a chirp signal generated in a signal generator acts as the digital Doppler receiver input, and its frequency, amplitude and other parameters are resolved. The system is also tested in Shanghai Astronomical Observatory, and the downconverted X-band signal from the Mars Express aircraft (MEX) is input to the system. The results verify that the behaviors of the developed digital Doppler receiver achieved the desired goal.