Group's Principle. Quadrature Mirror Filters And Realization

Quadrature mirror filter banks is a project which belongs to multi-sample rate digital signal process .It has important research value for wavelet, speech code, image compress and so on. The traditional method is that the impulse response of filter can be gotten by optimization under the perfect reconstruction condition. The performance of filters is not very good. The attenuation of stop-band is almost -44dB.The performance cannot satisfy the requirement for some application situation.For getting better filter performance, we design quadrature mirror filter banks using window function method. Considering the frequency response of filter change rapidly, we make the filter is perfect reconstruction on the point of center frequency. The error of reconstruction is small by the point. Applying the method of this article, we can get that the attenuation of stop-band is -75dB and the error of reconstruction is 0.0015. The simulation program and experiment result are provided .The correctness and validity are proved.The following is the content of this paper:The first chapter introduces the developing history and category of filter, points out the theory and fact meaning, research actuality and application research.The second chapter introduces the theory of multi-sample rate system including integer times decimate and interpose, multi-phase expression and identical transform of network structure.The third chapter introduces the concept and principle of filter banks. Two channel QMF banks and multi-channel QMF banks are discussed. The perfect reconstruction condition is provided for multi-channel QMF banks. Filter banks of tree structure are described.The fourth chapter discusses modulated filter banks. The theory and design method of prototype filter are provided.The fifth chapter introduces the development situation of digital integrate circuit technology. The development situation of DSP and FPGA are introduced too. The analysis indicates that hardware realization has no problem. The reconstruction condition of two channel QMF banks is analyzed and the FIR QMF banks are designed by windows function method. The MATLAB program and result analysis is provided. The simulation also be done by Simulink. It is indicated that the method is correct and efficient.