Patent ID: 7225213

Claim:
An interpolation filter for sampling frequency conversion of a digital input signal, the interpolation filter comprising: (a) a filter coefficient generator for generating various sets of filter coefficients as a function of a base function (BF), wherein the base function (BF) is generated on the basis of a time-limited power sine function h 1 (t), wherein each of the various sets of filter coefficients has in a useful signal frequency band Δf nutz of the digital input signal as an essentially equal amplitude response and different group delays τ, wherein the filter coefficient generator selects that filter coefficient set whose group delay τ has a minimal deviation from a set desired group delay; (b) a multiplier for multiplying the digital input signal by the filter coefficients of the selected filter coefficient set; and (c) an accumulator for accumulating the digital input signal weighted by the multiplication with the filter coefficients of the selected filter coefficient set.