An adaptive filter structure that requires zero multiplications for its implementation is introduced. The primary input signal is quantized using differential pulse code modulation (DPCM), and the DPCM outputs are processed by a conventional adaptive filter. The filter coefficients are updated using the sign algorithm. Under the assumption that the primary and reference input signals to the adaptive filter are zero-mean, wide-sense stationary, and Gaussian, theoretical results for the mean and mean-squared behaviour of the filter are also derived. A simulation example demonstrating the usefulness of the filter, as well as verifying the theoretical results and comparing the multiplication-free adaptive digital filter to the sign algorithm, is also presented. >
['V.J. Mathews']
An efficient FIR adaptive filter using DPCM and the sign algorithm