Multimode Receiver Technology Research Based On The Wavelet Recognition

With the development of digital communications diversification, the requirements of received signal processing continue to increase. For the receiver, identification and demodulation techniques of the multi-mode modulation signal aretwoimportant research fields about it. By dealing with the received signals, modulation recognition technology of communication signals estimates the signal parameters, such as the code rate, the carrier frequency and other information, to determine the type of communication signal modulation.Based on wavelet transform, this thesis mainly researches the digital modulation signal recognition methods, the automatic identification of the modulated signal ASK, FSK, PSK, QAM and theimplementation of FPGA for digital quadrature demodulation.First, this dissertation introduces the advantages in digital modulation type recognition of wavelet transform. Because of its efficiency, frequency localization features and multi-resolution analysis of characteristics, wavelet transform is an effective technique to extract the transient characteristics from different types of digital modulation signals. The wavelet coefficients for different types of digital signals is significantly different, thus it is very suitable for the identification of digital modulation signals. Second, analyzing the four digital communication signals in theory by the method of using wavelet transform results in different conversions, and then this dissertation establishes modulation recognition models to identify among classes and inner classes for the four digital communication signals. Finally, by using the digital quadrature demodulation method, this paper makes demodulation and simulation for multi-mode signals. Based on this, the implementation on FPGA for the digital quadrature demodulationis completed, and in the meantime, VHDL code wrote and demodulated in ISE realize its FPGA completion, and verifies its feasibilities.