Research And Implementation Of Satellite Communication Multi-mode Digital Receiver

Multi-mode data communication system refers to its modulation mode, data rate, coding mode and multi-mode modulation frequencies are variable, for multi-mode receiver, the need for parametric design, the signal of a receiver platform for different modes can be demodulated, so the structure of the receiver demodulates presents more challenges.In this paper, the multi-mode signal modulation and demodulation process is researched; the modulation scheme includes BPSK, QPSK, SQPSK, and information bit rate of coding prior is 20 Mbps or less and 1kbps step, which supports coding RS coding and convolutional coding. Focuses on digital IF signal demodulation process, a new convolution encoder structure is proposed, there is gain of 2dB higher than traditional convolutional code encoder when bit error rate at 10-4 coding. for a variety of information-rate mode, we designed a universal data acquisition modules, and synchronization algorithm based on simplified symbols Gardner algorithm is proposed and basic performance is guaranteed, it reduces hardware resource overhead. At the same time for the large carrier frequency offset synchronization, parameters in estimation algorithm based on maximum likelihood algorithm is modified. Finally, process of phase ambiguity and decoding is introducted; we proposed a non-data-assisted coding joint carrier phase recovery method.This paper verifies the feasibility of multi-mode modem hardware implementation, and achieved multi-mode signal processing from the sender to the receiver with FPGA-IF verification platform, software simulation and hardware simulation verified the theory of algorithms, at the same time a communication equipment which modulation scheme and information are variable is developed, the results show that when error rate is reached 10-6, the demodulation performance of EbN0 loss is about 1dB compared to theoretical value.