Patent ID: 6151614
Filing Date: 2000-11-21
Classification: H04B,H04M

Abstract:
An adaptive filter comprising:an input terminal for a filter input signal;a delay circuit comprised of a plurality of delay elements connected in series, the first delay element in the series having an input terminal connected to the filter input terminal, and a plurality of output taps, the first of the taps being connected to the filter input terminal to provide a zero-delay tap, and the remaining output taps being connected to the outputs of each of the delay elements;a path switch having a plurality of input terminals, each connected to one of the output taps, and being responsive to a path switch control signal to connect selected ones of the taps to outputs of the path switch as valid taps;a plurality of coefficient generating circuits, each connected to one of the outputs of the path switch, and responsive to the value of a signal at the connected path switch output, to an updating signal and to a coefficient clear signal to generate a tap coefficient value for one of the valid taps;a multiplier for each of the valid taps, each multiplier connected to the output of one of the coefficient generating circuits and to the output of the path switch for the corresponding valid tap;an adder for adding the outputs of the plurality of multipliers to generate an identification signal;a subtraction circuit for subtracting the identification input signal from the filter input signal to generate an error signal; anda tap control circuit responsive to the tap coefficient values for the valid taps, to signals at the output taps of the delay circuit and to the error signal, to perform the following functions:to divide all of the taps into a plurality of control subgroups comprised of equal numbers of contiguous taps;to select one of the control subgroups for updating a predetermined number of times in a particular selection order, the predetermined times and the selection order being based on the sums of the absolute values of the tap coefficients of valid taps in each of the control subgroups,to calculate an electric power value representing the sum of at least a selected sub-plurality of the output tap signals; and, based on the calculated sum,to generate the path switch control signal, the coefficient clear signal and the updating signal.