Digital adaptive filter for communications system, e.g. hands free communications in vehicles, has power estimation unit recursively smoothing increasing and decreasing input power asymmetrically

摘要

The filter includes a unit to successively update filter coefficients in accordance with tan input signal (x), an estimated power input of the input signal, and an error signal between the input signal filtered in the filter and a input signal propagated along an external path being modelled by the filter. A power estimation unit performs recursive smoothing for an increasing input power and a decreasing input power in an asymmetric fashion with different smoothing factors. In case the estimation is carried out in the frequency domain, the step size for the update of the filter coefficients may be adapted frequency band selectively. Independent claims are also included for a frequency domain adaptive filter, a sub-band adaptive filter, an acoustic echo canceller for a communication device, a hands free communication device, a teleconference communication system, a multimedia terminal equipment, a digital adaptive filtering method, a frequency domain adaptive filtering method.