DUPLEX ADAPTIVE DIGITAL FILTER AND METHOD OF OPERATION

An adaptive filter system has a first and a second filter subsystem of like construction, each having a series of delay elements for imparting a unit delay of one sampling interval to successive input samples in order to concurrently obtain a set of input samples of different sampling times. Each set of input samples are multiplied by respective coefficients, and the resulting values are added together for comparison with a reference signal. The coefficients are updated for each new set of input samples. For such updating, the first subsystem uses the step gain that is fixed at one, whereas the step gain used by the second subsystem is varied with time for faster convergence and smaller convergence error.