Patent ID: 7822210

Claim:
A television audio signal decoder, comprising: a separation device configured to run at a clock speed and to separate the left channel and right channel audio signals from the difference signal and a sum signal, wherein the sum signal includes the sum of the left channel audio signal and the right channel audio signal; and a configurable infinite impulse response (IIR) digital filter configured to run at a selected clock speed substantially faster than the clock speed of the separation device and to selectively use, over a sampling period, at least one set of filter coefficients multiple times to filter a difference signal, wherein the difference signal is produced by subtracting one of a left channel and a right channel audio signal from the other of the left channel and right channel audio signal, wherein the at least one set of filter coefficients is applied to the difference signal by a single multiplier in a recursive manner in a recursive loop to prepare the difference signal for separating the left channel and right channel audio signals, wherein the configurable IIR digital filter includes a feedback path and is configured to apply the at least one set of filter coefficients to the difference signal in a recursive manner, and wherein the at least one set of filter coefficients is changed between iterations of the recursive loop.