Design Of Uniform And Nonuniform Filter Banks

Filter banks are important in the multirate signal processing, and have been received great attention in recent years. If a signal is split into several subbands, the frequency characters can be utilized more efficiently. In a whole system that contains an analysis bank and synthesis bank, perfect reconstruction (PR) is usually the aim that filter banks are designed toward. However for actual application, as long as the distortions are under controlled tolerance, the design method which has fewer constraints can be performed easilyMultirate digital signal processing finds application in communications, subband coding of speech and images, radar, and in many other fields. The use of multiple sampling rates offers many advantages, such as reduced computational complexity for a given task, reduced transmission rate, and reduced storage requirement, depending on the application.The design methods for cosine-modulated filter banks are investigated. General nonlinear optimization techniques with many free parameters are typically employed which, in general, are complicated and quite time consuming. A simple method which optimizes a single parameter is proposed. Near perfect reconstruction cosine-modulated filter banks with high stop attenuation can be achieved using the proposed method.The method is based on the computation of an eigenvector of an appropriate real, symmetric, and positive-definite matrix, which is called eigenfilter approach. It is general enough to incorporate both time- and frequency-domain constraints. A prototype has been designed by using the method. The method is simple and easy to comprehension.In some applications such as audio coding and subband adaptive filters, a nonuniform frequency partitioning may be preferred. In the paper, a design method of nonuniform filter banks with rational sampling factors is presented. Many other design methods of nonuniform filter require significant modification in algorithm for designing filter bank with other sampling factors.Before ending the dissertation, we give a summary and point out some future works.