EP4564348A2

Efficient filtering with a complex modulated filterbank

Abstract

A filter 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 an non-uniform amplitude/frequency characteristic, comprises a complex analysis filter bank for generating a plurality of complex subband signals from the time domain input signals, a plurality of intermediate filters, wherein at least one of the intermediate filters of the plurality of the intermediate filters has a non-uniform amplitude/frequency characteristic, wherein the plurality of intermediate filters have a shorter impulse response compared to an impulse response of a filter having the filter characteristic, and wherein the non-uniform amplitude/frequency characteristics of the plurality of intermediate filters together represent the non-uniform filter characteristic, and a complex synthesis filter bank for synthesizing the output of the intermediate filters to obtain the time domain output signal.

EP4564348A2, drawing sheet 1
Sheet 1 of 1,200

Term

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Projected expiry passed 1 September 2026, 0.1 years ago.

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3 claims: 1 independent, 2 dependent

  1. 1
    Method for converting an impulse response signal indicative of the amplitude/frequency filter characteristic in the time domain into a filter definition signal, comprising:filtering the impulse response signal indicative of the amplitude/frequency filter characteristic in the time domain to obtain a plurality of complex valued subband signals forming the filter definition signal, wherein each complex valued subband signal of the plurality of complex valued subband signals corresponds to an impulse response for a subband filter (102) for a subband signal to be filtered by the subband filter (102), wherein at least one of the complex valued subband signals of the plurality of complex valued subband signals comprises at least two different non-vanishing values, wherein each complex valued subband signal of the plurality of complex valued subband signals is shorter than the impulse response signal indicative of the amplitude/frequency filter characteristic in the time domain, wherein the impulse response signal indicative of the amplitude/frequency filter characteristic in the time domain is a time domain FIR (Finite Impulse Response) filter, and wherein the method for converting comprises performing an extension with zeroes of the time domain FIR filter, wherein L complex valued subband signals are output as the plurality of complex valued subband signals, wherein L is equal to 64, and wherein the impulse response signal indicative of the amplitude/frequency filter characteristic in the time-domain is indicative of a non-uniform amplitude/frequency filter characteristic.