The Research Of Modulation Recognition Algorithm And Demodulation Algorithm Based On The Software Defined Radio

Software Defined Radio (SDR) is a kind of new radio communication architecture which was first proposed in 90's in last century. Its basic idea is to realize all kinds of radio communication functions, such as work band, kinds of modulation or demodulation, data format, encrypt mode and communication protocol by upgradable and displaceable software on a hardware platform which is opening, expanded and simple structure. And it makes wideband A/D and D/A converters close to the antenna, in order to develop more flexible and opening wireless communication system.In this dissertation, modulation recognition algorithm in software radio system is researched. The dissertation uses the spectral correlation theory as algorithm foundation because of the communication signals' cyclostationary character.On the base of the spectral correlation theory and its usage in modulation recognition, the dissertation has discussion and simulation for the modulation signals in order to find communication signals' spectral correlation characters, and then picks up character parameters to recognize communication signals. For AM, ASK, FSK, BPSK, QPSK and MSK, the recognition algorithm is researched and the flow is given., in which included single signal's recognition and two signals' recognition. The program simulates the recognition correctness under different SNR. Finally demodulation algorithm in software radio system is discussed, digital orthodoxy demodulation algorithm is the most important. And the signals which recognized correctly, such as AM, ASK, FSK, BPSK, QPSK and MSK, are discussed and simulated for their demodulation.