Study On Multi-mode Modulation And Demodulation And Algorithm Of Automatic Modulation Recognition In Software Radio

The basic idea of Software Radio (SR) is to construct a general hardware platform with openness, standardization and modularization. The generalization of SR must bring the multi-modularization, so the automatic multi-mode modulation recognition method comes into necessity to ensure correct demodulation. As a result, the automatic modulation recognition is one of the necessary functions. How to make the method of automatic modulation recognition adaptive to the demodulation method and realize the automatic reception and demodulation is one of the key technologies and must have wide application.In allusion to the status mentioned above, the contents finished in the dissertation are listed as follows:1,The three SR architectures were introduced and the wideband and band-pass sample architecture was proved as the practical one now in the present design condition. Based on the architecture, the general model of multi-mode modulation and demodulation were proposed.2,The extraction method of basic character parameter including envelope, frequency and phase was analyzed and three classification method of digital modulation were also discussed. When the channel condition is good, the parameter histogram distribution method was introduced to make a statistics of the three basic character parameters. According to the peak number, the 2ASK, 4ASK, 2PSK, 4PSK, 2FSK and 4FSK can be classified well. In the channel condition that is not so good, the decision theory method was adopted to extract four character parameters so that the classification of 2ASK, 4ASK, 2PSK, 4PSK, 2FSK and 4FSK was realized. The dissertation also proved theoretically almost all of the amplitude modulation signals could be classified with the parameter R and the recognition of their high-order form can be also finished together with some other parameters by parameter statistics method.3,The recognition of modulation signals under the low SNR condition is always the important research content of signal recognition. In the dissertation, the high order cumulants method was adopted to realize successfully the classification of 2ASK, 4ASK, 2PSK, 4PSK, 2FSK and 4FSK by extracting four character parameters based on several high order cumulants calculated.4,Some other methods of modulation recognition were also introduced including...