Research On Modulation/Demodulation And Signal Acquisition Based On SDR Platform

Software radio has been widely used in modern communications. The modulation, demodulation and the signal acquisition technology are studied, and related programs for short-wave communications are proofed and designed in this thesis.Firstly, the structure and the key techniques of the software radio system are analyzed, and then the principles and algorithms of the existing MPSK modulation and demodulation technology are presented and their performance are compared. Then the modified BPSK/QPSK combined modulation/demodulation algorithm based on the extension of signal set are discussed, and its performance compared with8PSK is simulated by Matlab. The improvement of the demodulation gain gives persuasive arguments that will be applied for the short-wave communication, then the corresponding program is designed.The acquisition algorithms of PN sequence are researched in the second half of the thesis. From acquisition time, application complexity and performance, the existing acquisition algorithms are analyzed and compared. For anti-offset, the acquisition algorithm of sub-sliding correlation based on FFT is given. Finally, the receiving program of burst waveform used with the sub-sliding correlation FFT acquisition algorithm is designed, simulated and implemented on SDR platform based on DSP TMS320C6713.