Research On Modulation&Demodulation Technology In Deep-Space Communication

Deep-Space Communications has a typical nonlinear VPAWGN channel, including the very low SNR (Singal-Noise Ratio), the Doppler Frequency Shift and the strict Power Limitation and high required reliability. As the information transmission modality of the telemetry system and the data transmission system in the Deep-Space Exploration Mission, Deep-Space Communication Modulation&Demodulation technology is the the key to the task. Therefore, the Deep-Space Communication Modulation&Demodulation System Model and the key modulation and demodulation technologies applied to the model must be researched.The Constant Envelope and Quasi-constant Envelope Modulation&Demodulation technologies in Deep-Space Communication are focused in this paper. Based on the analysis of Deep-Space channel basic characteristics, and the establishment of the basic Deep-Space Communication Modulation&Demodulation System Model and the simplified Model, the main emphases are laid on the Bandwidth Efficiency, the Power Efficiency and the Modulation&Demodulation System integrated implementation of the Constant Envelope Modulation such as the residual carrier modulation, the phase-shift keying modulation and the continuous phase modulation (CPM), and the Quasi-constant Envelope Modulation including IJF-OQPSK, FQPSK and EFQPSK. Some optimum algorithms for raising the Bandwidth Efficiency or the Power Efficiency are also be suggested and researched. At the end of the paper, some key technologies in the Modulation&Demodulation System, such as the IJF-OQPSK baseband shaping and Viterbi decoding algorithm, are implemented based on FPGA.