Reduction of Digital Filter Delay
AssigneeTelefonaktiebolaget L M Ericsson (publ)
InventorsDan Lusk, Tonu Trump
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Abstract
An apparatus for reducing a digital filter delay includes means for determining the magnitude response of a desired filter. Means form the real cepstrum of this magnitude response. Means transform the real cepstrum into a complex cepstrum of a corresponding minimum-phase filter having the same magnitude response as the desired filter. A filter applies a smoothly decaying shaping window to the complex cepstrum. Means transform the shaped complex cepstrum into an estimated minimum-phase filter.
Claims10
A method of reducing a digital filter delay, including the steps of
- determining a first finite sequence of coefficients representing a real cepstrum of a magnitude response of a desired digital filter,
- transforming said first sequence into a second sequence of coefficients representing a corresponding complex cepstrum,
- determining an estimate of a minimum-phase digital filter corresponding to said second sequence, where said transforming step includes shaping of coefficients to be included in said second sequence by applying a smoothly decaying window function.
An apparatus for reducing a digital filter delay, including
- means for determining a first finite sequence of coefficients representing a real cepstrum of a magnitude response of a desired digital filter,
- means for transforming said first sequence into a second sequence of coefficients representing a corresponding complex cepstrum,
- means for determining an estimate of a minimum-phase digital filter corresponding to said second sequence, where said transforming means includes means for applying a smoothly decaying window function for shaping coefficients to be included in said second sequence.
Dependencies are inferred from the claim text.