Adaptive digital filtering of differentially coded signals

In this paper the performance and realization of adaptive digital filters (ADF´s) for differentially coded signals have been studied. A general formula that realizes the LMS algorithm for differentially coded signals is first derived. We use this formula for realization of ADM and ADPCM ADF´s. Then, applying these algorithms to channel equalization, we study the performances of the two filters for the cases of using a time-varying and a constant convergence factor. If we consider the dynamic range and the sensitivity to the variation of parameter values as the important performance factors, the ADPCM ADF with a time-varying convergence factor is preferred. However, when we consider the system complexity, the use of the ADM ADF with a time-varying convergence factor is desirable.