Design of two-channel FIR filterbanks with rational sampling factors by using the frequency-response masking technique
Robert Bregović, T. Saramäki · 2004
This paper considers the use of the frequency respo nse masking (FRM) technique for designing finite-impulse response (FIR) filters generating nearly perfectreconstruction (NPR) two-channel filterbanks with r ational sampling factors in the case where the proce ssing unit between the analysis and synthesis banks signi ficantly changes the two input signals. In this parti cular case, even the use of the perfect-reconstruction fi lter bank is not enough to compensate the modifications performed at the processing unit due the aliasing e rrors occurring in the analysis bank. The only way to kee p these errors as low as possible is to use filter ba nks with very narrow transition bandwidths. Based on the pro perties of FIR filters, this implies the use of high o rder filters, requiring a larger number of multipliers and adders. In order to significantly reduce the number of the coefficients required by the overall filter bank implemen tation, this paper properly exploits the FRM technique for designing the above-mentioned two-channel filter banks. The benefits of using the modified FRM approach for generating NPR two-channel filterbanks with rationa l sampling factors is illustrated by means of an illu strative example.