Study On The Design And Applications Of Multirate Filter Banks

Multi-rate filter banks theory is the basis of multi-rate digital system, and it is one of research hotspots in the field of multi-rate digital system. The multi-rate filter banks which has linear phase and perfect reconstruction characteristic is called Linear Phase Perfect Reconstruction Filter Banks (LPPRFB). LPPRFB is closely used not only in many government fields such as air warning,electron confronting,ultra wide band radar and software wireless, but also in many civil fields such as mobile communications,image compress,wide band A/D transform and transient protect. As a result many research scholars have put up so much interest on the design of LPPRFB. But the difficulty in the design of M-channel LPPRFB is how to confirm the style and length of M analysis filters, and how to optimize and solute the coefficients of the analysis filters. Therefor this paper first analyzes and researches the style and length of M analysis filters. As far as the optimization and solution of LPPRFB coefficients, the design methodological distinctness consisting in design technique of filter banks are non-linear functions of optimization parameters, or are so sensitive on the change of the parameters, or are so sensitive on initial value, or contain so much integral operation in object function. So much reason lead to account complexity, and it is so difficult to realize the optimization and solution of LPPRFB coefficients.Therefore, the thesis is mainly about the design methods for LPPRFB. The main productions of this paper are as follows:1 .The general Perfect Reconstruction condition of linear phase two and three channel LPPRFB banks is deduced mathematically ,which consists of combination relation between analysis filter's length and relation of the coefficients among different analysis filters.2. Based on the design methods in time domain, we improve a new method for time-domain design and give the explicit design algorithm. Namely,we search for analysis filter coefficient matrix equation in restricted condition of linear phase of LPPRFB with recursion technique and conjugate grads method. 3.Multi-rate filter banks is designed that using optimum technique in this paper is adapted for the transient protection of EHV, and lots of simulation experimentations are made out in this paper.