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Echo canceler

A technology of echo cancellation and echo, which is applied in the direction of telephone communication, wired transmission system, electrical components, etc., can solve problems such as difficulty in concrete realization, increase in device scale, and large-capacity channels are not considered, and achieve excellent sound quality and echo small wave effect

Inactive Publication Date: 2008-06-04
OKI ELECTRIC IND CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Even if the double-talk detection signal is received from the double-talk detector operating in the sub-band at this point, performance degradation during double-talk cannot be prevented.
[0007] 2. There is no description of the specific tap configuration after the peak value is determined by the sub-band adaptive filter, so it is difficult to be specific
In the case of simple allocation, it may lead to the omission of the part that is really an important source of echo and the allocation
[0008] 3. In the prior art, it can be said that the echo canceller with a low sampling rate is the same as the echo canceller equipped with one in addition to the full-band echo canceller, resulting in an increase in the scale of the device
[0009] 4. The existing technology does not consider all temporary convergence large-capacity channels
For echo cancellers, dynamic resource allocation across channels is rather undesirable from this point of view

Method used

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no. 1 Embodiment approach

[0043] Hereinafter, a first embodiment of the present invention will be described.

[0044] 1 is a block diagram showing a communication terminal device having an echo canceller according to a first embodiment of the present invention, FIG. 2 is a block diagram showing a tap configuration controller, and FIG. 3( a ) shows an echo at 8 kHz sampling. The graph of the wave path, Fig. 3 (b) is a graph showing the adaptive filter coefficients estimated and grown at a low rate, Fig. 4 is a graph showing the echo path of Fig. 3 (a) under what conditions The resulting concept map, Figure 5 (a) is a graph showing the condition of the coefficient H2(k) input to the absolute value calculator 19-2, Figure 5 (b) is a graph showing the absolute value of the coefficient H2(k) input to the absolute value calculator 19-2, Figure 5 (c) is to show that the Figure 5 (b) The graph of the waveform smoothed by the absolute value of the coefficient H2(k), Figure 6 is represented by square dots ...

no. 2 Embodiment approach

[0127] Hereinafter, a second embodiment of the present invention will be described.

[0128] 7 is a block diagram showing a communication terminal device having an echo canceller according to a second embodiment of the present invention, and FIG. 8 is a block diagram showing a tap allocation controller, Figure 9 (a) is a graph showing the echo path at 8kHz sampling, Figure 9 (b) is a graph showing adaptive filter coefficients estimated and grown at a low rate, Figure 10 (a) is represented by sampling on the horizontal axis Figure 9 (b) A plot of the adaptive filter coefficients, Figure 10 (b) is a graph showing the absolute value of the coefficient H2(k) input to the absolute value calculator, Figure 11 (a) is a graph showing the state where the maximum value part is detected by the maximum peak detector 21, Figure 11 (b) is a graph showing a state in which the second assignment is assigned as adaptive filter coefficients.

[0129] 7 and 8 show a communication term...

no. 3 Embodiment approach

[0160] Hereinafter, a third embodiment of the present invention will be described.

[0161] FIG. 12 is a block diagram showing a communication terminal device having an echo canceller according to a third embodiment of the present invention, and FIG. 13 is a block diagram showing a tap allocation controller, Figure 14 (a) is a graph showing the echo path at 8kHz sampling, Figure 14 (b) is a graph showing the absolute value of the coefficient H2(k) input to the absolute value calculator, Figure 15 is a graph showing the tap position of the adaptive filter at the time of low-rate sampling in a square, Figure 16 (a) is a graph showing the positions of taps newly included in the range above TTHTAP3(1) by squares, Figure 16 (b) is a graph showing in squares where the tap positions newly included in the range above TTHAP3(2) are located.

[0162] The third embodiment differs from the second embodiment in that, as shown in FIGS. 12 and 13 , the tap arrangement controller 20 i...

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Abstract

An echo canceler, which uses an adder to add a pseudo echo created by an adaptive filter to an echo so as to cancel this echo, comprises combinations of subband filters (8,14) and sampling converters (9,15) that down sample audio signals; switches (10,16) that appropriately switch between the down sampling side and a full-band echo canceling side; and a tap arrangement controller (19) that uses a coefficient, which has been updated by the adaptive filter (17) using down sample signals, to optimize the tap arrangement, and outputs the optimized tap arrangement to the adaptive filter (17) during a full-band echo cancel.

Description

technical field [0001] The present invention relates to echo cancellers. Background technique [0002] Among the echo cancellers, there is an echo canceller disclosed in Japanese Patent Laid-Open No. 2003-134005 (Patent Document 1) as an echo canceller improved so as to reduce the calculation amount at the time of echo cancellation in a communication channel. device. [0003] In this echo canceller, an input signal from a communication channel is subbanded using a decimator and a sub band filter. The echo position determiner and peak detector are then used to identify the echo position within the sub-band and this signal is used for the control of the echo canceller. [0004] Thereby, the echo canceller can be controlled with a very small amount of calculation. [0005] However, the above-mentioned prior art has the following problems. [0006] 1. In the prior art, it is difficult to prevent performance degradation in double talk. In the prior art, the double-talk decis...

Claims

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Application Information

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IPC IPC(8): H04B3/23
CPCH04M9/082H04B3/23
Inventor 高田真资
Owner OKI ELECTRIC IND CO LTD
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