Study On Wavelet Transform Theory In Modulation Style Recognition Of Communication Signals

Signal’s automatic modulation recognition is an important research subject in the field of communication. With the rapid development of communication technology, modulation manner of digital communication signals becomes more and more complicated and various, and circumstance of signals also becomes increasingly dense. It results in the problem that the routine methods can hardly satisfy the practical requirements. So these strict demands, for instance, less signals’ priori knowledge, more identified modulation manners, higher recognition rate in low SNR and so on, have been presented for study on automatic modulation recognition of digital communication signals. Based on these demands and the existing analysis methods, a method based on wavelet transform in the classification for the four modulation styles of signals in modern communication is proposed. It uses the variance of instantaneous amplitude, instantaneous frequency and neighboring symbol difference phase as the parameters for the different class recognition. For the intra-class recognition, it chooses the peaks in histogram of instantaneous amplitude, instantaneous frequency and neighboring symbol difference phase. The method by the wavelet transform has several advantages, such as simple structure, fast calculation, easy to understand, convenient to implement, and visualization simulation in MATLAB software demo. Relative to the recognition method based on the original signal, it has a higher recognition rate.