Patent ID: 7711552

Claim:
Hardware apparatus for filtering a time domain input signal to obtain a time domain output signal, which is a representation of the time domain input signal filtered using a filter characteristic having a non-uniform amplitude/frequency characteristic, comprising: a complex analysis filter bank for generating L complex subband signals from the time domain input signal; a plurality of intermediate filters, each intermediate filter having a finite impulse response comprising (K H +K Q −1) filter taps, wherein one intermediate filter is provided for each complex subband signal; a complex synthesis filter bank for synthesizing the output of the intermediate filters to obtain the time domain output signal, a filter tap generator comprising a complex modulated filter bank based on a prototype filter comprising K Q ·L taps for filtering a finite impulse response signal indicative of the amplitude/frequency filter characteristic in the time domain and comprising K H ·L filter taps to obtain L complex valued subband signals as an intermediate filter definition signal, wherein each complex valued subband signal of the complex modulated filter bank of the filter tap generator corresponds to an impulse response for one intermediate filter comprising (K H +K Q −1) filter taps; wherein at least one of the complex valued subband signals of the complex modulated filter bank of the filter tap generator comprises at least two different non-vanishing values; wherein each complex valued subband signal of the modulated filter bank of the filter tap generator comprising (K H +K Q −1) filter taps is shorter than the impulse response signal comprising K H ·L filter taps provided to the filter tap generator; wherein the plurality of intermediate filters is operative to receive the intermediate filter definition signal from the filter tap generator; wherein each intermediate filter of the plurality of intermediate filters is operative to have an impulse response depending on the intermediate filter definition signal; wherein at least one of the intermediate filters of the plurality of the intermediate filters has a non-uniform amplitude/frequency characteristic; wherein the non-uniform amplitude/frequency characteristics of the plurality of intermediate filters together represent the non-uniform filter characteristic; and wherein L, K Q and K H are positive integers.