Multi-resolution PR NMDFBs for programmable variable bandwidth filter in wideband digital transceivers

This paper describes a novel application of perfect reconstruction (PR) non-maximally decimated filter banks (NMDFBs). PR non-maximally decimated analysis/synthesis chains are used for performing resampling, channelization and filtering in very wideband software defined radios. Digital wideband filtering is currently limited by the hardware clock speed which constrains the maximum signal bandwidth that can be processed digitally. Polyphase channelizers decrease the sample rate of the input signals and parallelize the wideband filtering process at cost of a single filter. In this paper we show how to assemble multiple-tier PR analysis/synthesis channelizer chains for implementing, in a very efficient way, variable bandwidth digital filters and multi-resolution systems operating on very wideband signals. When an internal tier analysis channelizer is applied to a single output channel of a first external tier analysis channelizer it decomposes this channel in multiple narrower subchannels and, by applying appropriate complex processing elements to those sub-channels we can modify the designed filter bandwidth as desired.