A one-stage look-ahead algorithm for delta modulators

During the last 15 years, several different adaptive delta modulator (ADM) algorithms have been reported. Zetterberg and Uddenfeld (1974) and Chan and Anderson (1982) have shown that the performance of these algorithms can be improved by using 'look-ahead encoding', which is also referred to as 'delayed decision encoding'. The present investigation is concerned with a general technique which can be employed with any of these algorithms to effect a one-stage look ahead. It is pointed out that the presented technique does not require the calculation of two encoding paths. Another advantage is that the decision circuitry does not have to choose the optimum path which minimizes a mean-square error or absolute error criterion.