method and device for adaptive filtering using the sign algorithm

摘要

An input signal is filtered for creating an output signal using an adaptive filter. An error signal is derived from the output signal. The adaptive filter has coefficient whose value can be modified. A value of a coefficient is modified using a derived updating amount. The updating amount is obtained from the product of a value of the input signal, a value of the polarity of the error signal, and a step gain. The step gain has the form 2K with K being an integer and being dependent on a magnitude of the value of the error signal and on a step gain parameter. The updating amount is dependent on both the magnitude and the polarity of the error signal, therefore allowing a precise update of the coefficient. The specific form of the step gain allows a fast derivation of the product.