US 2001/0024499 A1Published application

Adaptive filter and echo canceller using the same

AssigneeNEC Corporation

InventorAtsushi Hasegawa

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Abstract

An adaptive filter allowing rapid adaptation to a sudden and great change in a system to be estimated is disclosed A memory stores position information indicative of a signal block connected to each of M filter circuits and power information obtained from K filter coefficients generated by each of the M filter circuits. A valid/invalid block selector selects one as an invalid block from the M signal blocks connected to the M filter circuits and determines position information indicative of a selected signal block as an invalid block and a corresponding filter circuit that has been connected to the selected signal block. The position information indicative of the selected signal block is appended to a queue of a shift register and position information is output from a head of the queue. Based on the corresponding filter circuit and the position information received from the shift register, a matrix switch connecting M filter circuits and M signal blocks is controlled.

Claims15

Dependent claims

An adaptive filter comprising:

N signal blocks obtained by dividing a serial input signal by K, wherein N, K is an integer greater than 1;
M (M<N) filter circuits, each of which generates K filter coefficients for one of the N signal blocks;
a switch for connecting M signal blocks selected from the N signal blocks to respective ones of the M filter circuits;
and
a controller controlling interconnection of the switch based on the K filter coefficients generated by each of the M filter circuits, wherein the controller comprises:
a memory for storing position information indicative of a signal block connected to each of the M filter circuits, power information obtained from the K filter coefficients generated by each of the M filter circuits;
a selector for selecting one as an invalid block from the M signal blocks connected to the M filter circuits to determine position information indicative of a selected signal block as an invalid block and a corresponding filter circuit that has been connected to the selected signal block;
a shift register for storing a queue of position information, wherein the position information indicative of the selected signal block is appended to the queue and position information is output from a head of the queue;
and
a switch controller controlling the switch using the corresponding filter circuit determined by the selector and the position information received from the shift register.

7 more elements

A control method for an adaptive filter comprising:

N signal blocks obtained by dividing a serial input signal by K, wherein N, K is an integer greater than 1;
M (M<N) filter circuits, each of which generates K filter coefficients for one of the N signal blocks;
and
a switch for connecting M signal blocks selected from the N signal blocks to respective ones of the M filter circuits, the method comprising the steps of:
a) storing position information indicative of a signal block connected to each of the M filter circuits, power information obtained from the K filter coefficients generated by each of the M filter circuits;
b) selecting one as an invalid block from the M signal blocks connected to the M filter circuits to determine position information Indicative of a selected signal block as an invalid block and a corresponding filter circuit that has been connected to the selected signal block;
c) storing a queue of position information, wherein the position information indicative of the selected signal block is appended to the queue and position information is output from a head of the queue;
and
d) controlling interconnection of the switch using the corresponding filter circuit determined by the selector and the position information received from the shift register.

6 more elements

An echo canceller comprising:

an unknown system to be estimated;
an adaptive filter for adapting to the unknown system by adjusting filter coefficients;
and
a adaptation controller controlling the adaptive filter based on an input signal, an echo signal, and a residual signal obtained by subtracting the echo signal from an output of the adaptive filter,
wherein the adaptive filter comprises:
N signal blocks obtained by dividing the input signal by K, wherein N, K is an integer greater than 1,
M (M<N) filter circuits, each of which generates K filter coefficients for one of the N signal blocks;
a switch for connecting M signal blocks selected from the N signal blocks to respective ones of the M filter circuits;
and
a controller controlling interconnection of the switch based on the K filter coefficients generated by each of the M filter circuits, wherein the controller comprises:
a memory for storing position information indicative of a signal block connected to each of the M filter circuits, power information obtained from the K filter coefficients generated by each of the M filter circuits;
a selector for selecting one as an invalid block from the M signal blocks connected to the M filter circuits to determine position information indicative of a selected signal block as an invalid block and a corresponding filter circuit that has been connected to the selected signal block;
a shift register for storing a queue of position information, wherein the position information indicative of the selected signal block is appended to the queue and position information is output from a head of the queue;
and
a switch controller controlling the switch using the corresponding filter circuit determined by the selector and the position information received from the shift register.

12 more elements

Dependencies are inferred from the claim text.