SUB-BAND CODERS, DECODERS AND FILTERS

摘要

A pair of filters (H1H2) split an input signal into two frequency sub-bands (defined by a transition frequency) which are down-sampled and coded: after sample rate restoration the signals are filtered (K1K2) and combined. To reduce signal delays, the delay response of each filter is non-constant, having a maximum at or beyond the transition frequency. Preferably non-quadrature filter pairs are used. Filters may be cascaded for more than two sub-bands.