A Channel Combiner approach for the design of Near Perfect Reconstruction non uniform Filter Banks

In this paper, a class of non uniform filter banks (NUFBs) are built using uniform filter banks in a simple and efficient manner. The uniform filter bank is realized using Cosine modulation so that the whole filter bank structure can be implemented from a single FIR, Type 1 prototype filter. The Cosine Modulated Filter Bank (CMFB) is designed to satisfy Near Perfect Reconstruction (NPR) conditions such that the 3dB point of the prototype filter is optimized at π/(2M). Channel combiners are employed to combine the sub-bands of uniform filter bank (FB). The NUFB is constructed for even and odd combinations of uniform filter bank. A rigorous analysis of the distortion function is performed to examine the significance of channel combination. A hardware implementation of the NUFB with direct structure has also been done in Virtex-6 FPGA and functionally verified. The method was found to be simple.