JPH11313014A - Band divided echo canceler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a band divided echo canceler, with which echo can be erased in average manner for each band, for updating a step size for each band. SOLUTION: This band divided echo canceler is provided with an FIR filtering part 51 for each band for synthesizing the pseudo echo signals of respective bands by convolving divided received signals and filter coefficients on respective bands, subtracter 61 for each band for calculating a residual signal for each band by subtracting the pseudo echo for each band from divided transmission signals, received signal level calculating part 141 for each band for calculating the level of a received signal on each band, step size determining part 151 for determining the step size of each band reflecting with the characteristics of each band based on the received signal level on each band and coefficient updating part 71 for each band for updating the filtering coefficient of the FIR filtering part on each band so that the residual echo contained in the residual signal can be closer to zero while inputting the received signal on each band, residual signal and step size on each band. Thus, the echo can be erased for each band in the average manner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a band-division echo canceller for canceling an echo generated in a video conference system or the like.

[0002]

2. Description of the Related Art An "echo canceller" is a technique for estimating an impulse response of an echo path having unknown characteristics by a coefficient adaptive updating algorithm such as a learning identification method, and, based on the estimated impulse response, converting an echo signal from a received signal into an echo signal. The pseudo echo signal approximated to the above is synthesized, and the pseudo echo signal is subtracted from the transmission signal to eliminate the echo signal included in the transmission signal.

[0003] "Impulse response" refers to a response obtained as a transmission signal when a predetermined pulse is passed through the echo path as a reception signal in the absence of a call signal on the transmission side. Generally, a pseudo echo signal is an adaptive finite impulse response (FIR: Finite Impulse Response) using an impulse response as a filter coefficient.
nse) The signal is synthesized by passing the received signal through a filter.

When updating the filter coefficient based on the learning identification method, the convergence speed is slow if the value of the step size is small. Increasing the step size speeds up convergence,
When the received signal level is small, the estimation accuracy of the impulse response is deteriorated, and the echo cancellation amount is deteriorated.

In a conventional echo canceller disclosed in Japanese Patent Publication No. Sho 64-5775, for example, as shown in FIG. 20, the correction amount at the time of updating the filter coefficient is multiplied by a coefficient determined by the level of the received signal. There has been proposed a method for stably obtaining a fixed amount of erasure regardless of the level of a received signal.

In FIG. 20, a reception signal input terminal 1 is
The received signal y (i) is input from the received signal transmission path, and the received signal output terminal 2 outputs the received signal y (i) to an echo path leading to the transmission signal input terminal 3. Transmission signal input terminal 3
Is a transmission signal x in which a transmission signal on the transmission side is superimposed on an echo generated when the reception signal y (i) wraps around the echo path.
(I), and the transmission signal output terminal 4 outputs the transmission signal x
The residual signal e (i) obtained by subtracting the pseudo echo signal r (i) from (i) is output to the transmission signal transmission line.

[0007] The FIR filter section 5 receives the received signal stored in the received signal register 501 and the coefficient register 50.
2 is convoluted with the filter coefficient stored in the product-sum unit 503 to synthesize a pseudo echo signal r (i) on the echo path from the reception signal output terminal 2 to the transmission signal input terminal 3, and a subtractor Output to 6.

The subtractor 6 subtracts the pseudo echo r (i) synthesized by the FIR filter unit 5 from the transmission signal x (i) input from the transmission signal input terminal 3 to obtain an echo included in the transmission signal. Is output as the residual signal e (i).

In the coefficient updating section 7a, the coefficient register 5
02, filter coefficients h ₀ (i), h ₁ (i),.
h _n-1 (i) is sequentially updated so that the residual echo included in the residual signal approaches zero.

In a general echo canceller, a correction amount 修正 h _j (i) of a filter coefficient h _j (i) shown below is obtained using a fixed value step size α ₀ based on a learning identification method. In the correction circuit 702, a correction term 2y (i) ² / (B + y) determined by the level of the received signal y (i) using the sum of squares of the received signal calculated by the square-sum operation circuit 701, where B is a constant. (I) ² ) is obtained, and the above-mentioned correction amount Δh _j (i) is multiplied by this.

△ h _j (i) = α ₀ Σe (k) y (j + k)
/ Σy (m) ² Here, the range of 分子 in the numerator is k = 0 to 15, and the range of Σ in the denominator is m = 0 to n−1.

That is, the correction amount of the filter coefficient is obtained by using the variable value step size α obtained by the correction circuit 702. In this way, control is performed so that the cancellation amount represented by the ratio between the transmission signal and the residual signal becomes substantially constant.

When the above method is applied to a band division echo canceller, the above method is applied independently to each band of a band-divided received signal, and the resultant residual signal of each band is synthesized. Then, by obtaining the entire residual signal, it is possible to obtain a method of stably obtaining a fixed amount of cancellation regardless of the level of the received signal in each band.

In FIG. 22, a reception signal input terminal 1, a reception signal output terminal 2, a transmission signal input terminal 3, and a transmission signal output terminal 4 correspond to FIG. The reception signal input from the reception signal input terminal 1 is applied to a reception-side band division filter 11.
Is divided into N bands. The FIR filter units 51 to 5N of the respective bands receive the divided reception signals, perform convolution with the filter coefficients of the respective bands, synthesize the pseudo echo signals of the respective bands, and provide the subtractors 61 to 6N of the respective bands. Output.

The subtractors 61 to 6N of the respective bands subtract the pseudo echoes of the respective bands from the signals of the respective bands obtained by dividing the transmission signal input from the transmission signal input terminal 3 by the transmission-side band division filter 12, and Each time, a residual signal in which an echo included in the transmission signal is eliminated is output.

The residual signal of each band is converted to a band synthesizing filter 13.
And a signal to be output from the transmission signal output terminal 4 to the transmission signal transmission path is obtained. Step size determination unit 70 for each band
21 to 702N determine the step size of each band,
The coefficient update units 71 to 7N of each band receive the received signal, the residual signal, and the step size of each band, and the FIR filter units 51 to 5N of each band receive the residual echo included in the residual signal close to zero. Update the filter coefficients. The coefficient updating unit 7a is applied to the coefficient updating units 71 to 7N of each band, and the correction circuit 702 is applied to the step size determining units 7021 to 702N of each band.

In a conventional echo canceller disclosed in, for example, Japanese Patent Publication No. 2-62975, FIG.
As described above, there has been proposed a method of increasing the convergence speed of the echo canceller by changing the step size depending on the residual echo, and securing a required amount of echo cancellation.

In FIG. 21, a reception signal input terminal 1, a reception signal output terminal 2, a transmission signal input terminal 3, a transmission signal output terminal 4, an FIR filter unit 5, and a reception signal register 50
1; a coefficient register 502; a sum-of-products 503;
And the square-sum operation circuit 701 correspond to FIG.

The correction value generating circuit 703 of the coefficient updating unit 7b uses the filter coefficient h ₀ (i) in the coefficient register 502,
When h ₁ (i),..., h _n-1 (i) are sequentially updated based on the learning identification method, the step size control circuit 705 causes the current and past residual signal sequences e (i), e (I-
1),... Are averaged, and a step size that guarantees a stable adaptive operation of the echo canceller is output to the correction value generation circuit 703, and the correction value generation circuit 703 corrects the filter coefficient using this step size. Calculate the amount.

The coefficient updating circuit 704 updates the contents of the coefficient register 502 by adding the correction amount for each sample. Here, in order for the echo canceller to guarantee a stable adaptive operation, it is necessary to satisfy 0 <α <2 with respect to the step size α. Further, considering the amount of echo cancellation and the convergence time, the condition of the step size α is 0. It is also stated that <α ≦ 1.

When the above method is applied to a band-division echo canceller, in FIG. 22, the coefficient updating units 7b are provided in the coefficient updating units 71 to 7N of each band, and the The step size control circuit 705 is applied.

[0022]

When the method shown in FIGS. 20 and 21 is applied to a band division type echo canceller as shown in FIG. 22, the reception signal level of each band or the residual echo level in each band. Since the step size is calculated on the basis of the above equation, the step size is large and the amount of echo cancellation is large in a band with a large level, but there is a problem that it is difficult to eliminate the echo in a band with a small level because the step size is small.

The present invention has been made to solve the above-mentioned problems, and is a band-division echo canceller that updates the step size for each band. The purpose is to obtain a split-type echo canceller.

[0024]

A band division type echo canceller according to the present invention performs a convolution operation of a reception side band division filter for dividing a reception signal, and a filter coefficient of each band with the divisional reception signal. An FIR filter section for each band that synthesizes a pseudo echo signal of each band, a transmission-side band division filter that divides a transmission signal, and subtracts the pseudo echo signal of each band from the divided transmission signal to obtain each band. Subtracters for each band for calculating the residual signal of
A band synthesizing filter for synthesizing a residual signal of each band, a received signal level calculating means for inputting a received signal and calculating a level thereof, and a step size determining unit for determining a step size of each band based on the received signal level. The reception signal, the transmission signal, and a double talk detection unit that detects double talk based on the residual signal, and when the detection result of the double talk detection unit is not in a double talk state, the reception signal of each band, Based on the residual signal of each band and the step size of each band determined by the step size determining unit, the filter coefficient of the FIR filter unit of each band is updated so that the residual echo included in the residual signal approaches zero. And a coefficient updating unit for each band.

In the band-division echo canceller according to the present invention, the reception signal level calculation means may include a reception signal level of each band for calculating a reception signal level of each band divided by the reception-side band division filter. This is a calculation unit.

In the band-division echo canceller according to the present invention, the reception signal level calculation means may be configured to calculate the reception signal level of each band divided by the reception-side band division filter. A calculating unit;
This is a reception signal level calculation unit that calculates the level of the reception signal in the entire band from the reception signal input terminal.

Further, in the band division type echo canceller according to the present invention, the reception signal level calculation means is a reception signal level calculation unit for calculating the level of the reception signal in the entire band from the reception signal input terminal. .

Further, in the band-division echo canceller according to the present invention, the step size determining section has a plurality of step sizes of each band as a table, and selects one table corresponding to the input received signal level. It has a step size table storage unit for determining the step size of each band.

Further, in the band division type echo canceller according to the present invention, the step size determining section includes a basic step size storing section for each band having a basic step size of each band, an input received signal level and each of the bands. And a multiplier for each band to be multiplied by the basic step size.

A band division type echo canceller according to the present invention comprises: a reception side band division filter for dividing a reception signal;
An FIR filter section for each band for performing a convolution operation of the divided reception signal and a filter coefficient for each band to synthesize a pseudo echo signal for each band, a transmission-side band division filter for dividing a transmission signal, A subtractor for each band for subtracting the pseudo echo signal for each band from the transmitted signal to calculate a residual signal for each band, a band synthesis filter for synthesizing the residual signal for each band, and a residual signal. A residual signal level calculating means for calculating the input level, a step size determining unit for determining a step size of each band based on the residual signal level, and the received signal, the transmitted signal, and the residual signal. A double talk detecting unit that detects double talk based on the received signal of each band, if the detection result of the double talk detecting unit is not in a double talk state, Based on the difference signal and the step size of each band determined by the step size determination unit, the filter coefficient of each band for updating the FIR filter unit of each band is updated so that the residual echo included in the residual signal approaches zero. And a coefficient updating unit.

In the band-division echo canceller according to the present invention, the residual signal level calculating means may include a residual signal level calculating means for calculating a residual signal level of each band divided by the transmission-side band division filter. This is a difference signal level calculator.

Further, in the band division type echo canceller according to the present invention, the residual signal level calculation means may include a residual signal level calculation means for calculating a residual signal level of each band divided by the transmission side band division filter. A difference signal level calculator,
The residual signal level calculator calculates the level of the residual signal of the entire band from the band synthesis filter.

In the band-division echo canceller according to the present invention, the residual signal level calculating means is a residual signal level calculating section for calculating the level of the residual signal of the entire band from the band combining filter. Things.

Further, in the band-division echo canceller according to the present invention, the step size determining section has a plurality of step sizes of each band as a table and selects one table corresponding to the input residual signal level. And a step size table storage unit for determining the step size of each band.

Further, in the band-divided echo canceller according to the present invention, the step size determining section includes a basic step size storage section for each band having a basic step size for each band, an input residual signal level, and And a multiplier for each band for multiplying the basic step size of the band.

[0036] A band division type echo canceller according to the present invention comprises: a reception side band division filter for dividing a reception signal;
An FIR filter section for each band for performing a convolution operation of the divided reception signal and a filter coefficient for each band to synthesize a pseudo echo signal for each band, a transmission-side band division filter for dividing a transmission signal, A subtractor for each band for subtracting the pseudo echo signal for each band from the transmitted signal to calculate a residual signal for each band, a band synthesis filter for synthesizing the residual signal for each band, and a received signal. Receiving signal level calculating means for calculating the level, residual signal level calculating means for inputting the residual signal and calculating the level, and echo canceling amount of each band based on the received signal level and the residual signal level. , A step size determination unit that determines the step size of each band based on the amount of echo cancellation of each band, the reception signal, and the transmission signal. If, and the double-talk detector for detecting a double-talk on the basis of the residual signal, the detection result of the double-talk detector is not a double-talk state,
Based on the received signal of each band, the residual signal of each band, and the step size of each band determined by the step size determination unit, the residual echo included in the residual signal is reduced to a value close to zero. And a coefficient update unit for each band for updating the filter coefficient of the FIR filter unit.

In the band-division echo canceller according to the present invention, the reception signal level calculation means may include a reception signal level of each band for calculating a reception signal level of each band divided by the reception-side band division filter. As a calculation unit, the residual signal level calculation means is a residual signal level calculation unit for each band that calculates the level of the residual signal of each band divided by the transmission-side band division filter.

In the band-division echo canceller according to the present invention, the reception signal level calculation means may include a reception signal level of each band for calculating a reception signal level of each band divided by the reception-side band division filter. A calculating unit;
A reception signal level calculation unit for calculating the level of the reception signal of the entire band from the reception signal input terminal; and the residual signal level calculation means, wherein the level of the residual signal of each band divided by the transmission side band division filter is used. , And a residual signal level calculator for calculating the level of the residual signal of the entire band from the band synthesis filter.

Further, in the band division type echo canceller according to the present invention, the reception signal level calculation means is a reception signal level calculation unit for calculating the level of the reception signal in the entire band from the reception signal input terminal, and The signal level calculation means may be a residual signal level calculation unit that calculates the level of the residual signal of the entire band from the band synthesis filter.

Further, in the band division type echo canceller according to the present invention, the step size determining section has a plurality of step sizes of each band as a table, and selects one table corresponding to the inputted echo cancellation amount. It has a step size table storage unit for determining the step size of each band.

Further, in the band-division echo canceller according to the present invention, the step size determining section includes a basic step size storage section for each band having a basic step size for each band, And a multiplier for each band to be multiplied by the basic step size.

Further, in the band division echo canceller according to the present invention, the double talk detecting section outputs a detection result to the step size determining section, and the step size determining section determines that the detection result is not in a double talk state. In this case, the operation is performed to determine the step size of each band, and in the double talk state, the step size determination processing of each band is stopped.

Further, the band division type echo canceller according to the present invention further inputs the determined step size of each band, and sets the value to 0 if the value is 0 or less, and 1 if the value is 1 or more.
It is provided with a clip circuit for clipping.

Further, the band division type echo canceller according to the present invention further inputs the determined step size of each band, and updates the coefficient when the input step size exceeds the set threshold value. It is provided with a step size monitoring unit for controlling so as not to exist.

Further, the band-division echo canceller according to the present invention further receives a received signal, a residual signal, or an echo cancellation amount, calculates a difference from the preceding sample, and sets a threshold value at which the difference is set. Is provided with a difference monitoring unit that controls the step size determination unit so as to maintain the previous step size without changing the step size of each band for samples exceeding.

Further, in the band division type echo canceller according to the present invention, the difference monitoring section updates the threshold value with a residual signal level.

Further, in the band-division echo canceller according to the present invention, the step size determining unit performs the step size determining process once in a plurality of times.

[0048]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 A band-division echo canceller according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of a band division echo canceller according to Embodiment 1 of the present invention. In the drawings, the same reference numerals indicate the same or corresponding parts.

In FIG. 1, reference numeral 1 denotes a reception signal input terminal;
Is a reception signal output terminal, 3 is a transmission signal input terminal, 4 is a transmission signal output terminal, 11 is a reception side band division filter, 12 is a transmission side band division filter, 13 is a band synthesis filter, 1
5 is a step size determination unit, and 16 is a double talk detection unit.

Also, in FIG.
To N, 61 to 6N are subtractors for bands 1 to N, 71 to 7N are coefficient update circuits for bands 1 to N, 141
-14N are reception signal level calculation units for bands 1-N.

Received signal input terminal 1 and received signal output terminal 2
, Transmission signal input terminal 3, transmission signal output terminal 4, reception side band division filter 11, transmission side band division filter 12
The band synthesis filter 13, the FIR filter units 51 to 5N for each band, and the subtractors 61 to 6N for each band correspond to FIG.

Next, the operation of the band-division echo canceller according to the first embodiment will be described.

Received signal level calculators 141 to 1 for each band
The 4N receives the received signal of each band, calculates the level of each band by, for example, calculating the sum of squares, and outputs the level to the step size determination unit 15.

The step size determining unit 15 determines the step size of each band reflecting the characteristics between the bands based on the received signal level of each band, and updates the coefficient of each band.
To 7N.

The double-talk detector 16 receives, for example, a received signal, a transmitted signal, and a residual signal, detects double-talk, and outputs the detection result to the coefficient updating units 71 to 7N of the respective bands.

The coefficient update units 71 to 7N of the respective bands receive the received signal and the residual signal of each band, the step size of each band determined by the step size determination unit 15, and the detection result of the double talk detection unit 16. When the detection result of the double talk detecting unit 16 is not in the double talk state, the filter coefficients of the FIR filter units 51 to 5N of each band are updated using the above step size so that the residual echo included in the residual signal approaches zero. However, in the case of the double talk state, the coefficient is not updated.

When the detection result of the double-talk detector 16 is not in the double-talk state, the coefficient updating unit 7p outputs the received signal y in an arbitrary band p (p is an integer of 1 to N).
_p (i), the residual signal e _p (i) and the step size α _p are input, and the filter coefficient h _p , ₀ (i) of the FIR filter unit 5p is set so that the residual echo included in the residual signal approaches zero. ,
_{h p, 1 (i),} ···, h p, n-1 () (n is the number of taps of the filter) sequentially updated.

Based on the learning identification method, the step size α _p
Is used to correct the filter coefficient h _p , _j (i) for the correction amount Δh _p ,
_j: (i) formula _{△ h p, j (i)} = α p Σe p (k) y p (j +
k) / determined by Σy _p (m) ^2, by adding this h _p, the _j (i), obtaining a _{h p, j (i + 1} ). Here, the range of Σ in the numerator of the above formula is k = 0 to 15, and the range of Σ in the denominator is m = 0 to n−1.

As described above, the received signal level of each band is input to the step size determination unit 15, and the step size determination unit 15 reflects the characteristics between the bands based on the received signal level of each band. By determining the step size, the coefficient is updated by securing a certain size in the step size even in a band of a small level, as compared with a case where the step size of each band is determined only by the level of the received signal in each band. Therefore, echo cancellation can be performed in each band average.

The band-division echo canceller according to the first embodiment has a reception signal input terminal 1 for inputting a reception signal from a reception signal transmission line and a transmission signal input terminal 3 for receiving a reception signal.
A reception signal output terminal 2 for outputting to an echo path leading to
A transmission signal input terminal 3 for inputting a transmission signal in which a communication signal on the transmission side is superimposed on an echo generated when a reception signal wraps around an echo path, and a residual signal obtained by subtracting a pseudo echo signal from the transmission signal to a transmission signal transmission path Signal output terminal 4 for outputting the signal to the receiving side, and receiving side band division filter 11 for dividing the received signal
FIR filter units 51 to 5N for each band for performing a convolution operation of the divided reception signal and the filter coefficient for each band to synthesize a pseudo echo signal for each band, and a transmission-side band division filter for dividing a transmission signal 12, subtractors 61 to 6N for each band for calculating the residual signal of each band by subtracting the pseudo echo of each band from the divided transmission signal, and a band synthesizing filter 13 for synthesizing the residual signal of each band A reception signal level calculation unit for each band that receives a reception signal of each band and calculates a level, and a step size determination unit 1 that determines a step size of each band based on the reception signal level of each band
5 and the received signal of each band, the residual signal, and the step size of each band determined by the step size determining unit 15, and the FIR filter of each band so that the residual echo included in the residual signal approaches zero. And coefficient updating units 71 to 7N for the respective bands for updating the filter coefficients of the respective units, so that echoes can be canceled on average in each band.

Embodiment 2 Embodiment 2 A band division echo canceller according to Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 2 is a diagram showing a configuration of a band division echo canceller according to Embodiment 2 of the present invention.

In the echo canceller shown in FIG. 1, as shown in FIG.
1 to 14N, the residual signal level calculator 1 for each band
71 to 17N are provided.

The residual signal level calculators 171-1 of the respective bands
7N receives the residual signal of each band, calculates the level of each band, and outputs it to the step size determination unit 15.

The step size determining section 15 determines the step size of each band reflecting the characteristics between the bands based on the residual signal level of each band, and the coefficient updating section 71 of each band.
To 7N.

The coefficient update units 71 to 7N of each band receive the received signal and the residual signal of each band, the step size of each band determined by the step size determination unit 15, and the detection result of the double talk detection unit 16. When the detection result of the double talk detecting unit 16 is not in the double talk state, the filter coefficients of the FIR filter units 51 to 5N of each band are updated using the above step size so that the residual echo included in the residual signal approaches zero. However, in the case of the double talk state, the coefficient is not updated.

As described above, the residual signal level of each band is input to the step size determining unit 15, and the step size determining unit 15 reflects the characteristics between the bands based on the residual signal level of each band. By determining the step size of each band, even in a band of a small level, the coefficient is updated while securing a certain size in the step size, so that echo cancellation can be performed in each band on average.

Embodiment 3 Embodiment 3 A band-division echo canceller according to Embodiment 3 of the present invention will be described with reference to the drawings. FIG. 3 is a diagram showing a configuration of a band division echo canceller according to Embodiment 3 of the present invention.

In the echo canceller shown in FIG. 1, as shown in FIG.
1 to 14N, and a residual signal level calculator 1 for each band.
71 to 17N and an echo cancellation amount calculation unit 18 are provided.

Received signal level calculators 141 to 1 for each band
4N receives the received signal of each band, calculates the level of each band, and outputs it to the echo cancellation amount calculation unit 18.
Also, the residual signal level calculators 171 to 17N of the respective bands
Receives the residual signal of each band, calculates the level of each band, and outputs it to the echo cancellation amount calculation unit 18.

The echo cancellation amount calculating section 18 receives the received signal level of each band and the residual signal level of each band, and divides the residual signal level by the received signal level in each band, for example. The echo canceling amount of the band is calculated and output to the step size determining unit 15.

The step size determining section 15 determines the step size of each band based on the echo cancellation amount, and outputs it to the coefficient updating sections 71 to 7N of each band. The coefficient update units 71 to 7N of the respective bands receive the received signals and the residual signals of the respective bands, the step sizes of the respective bands determined by the step size determination unit 15, and the detection results of the double talk detection unit 16,
When the detection result of the double talk detecting unit 16 is not in the double talk state, the filter coefficients of the FIR filter units 51 to 5N of each band are updated using the above step size so that the residual echo included in the residual signal approaches zero. In the case of the double talk state, the coefficient is not updated.

As described above, the amount of echo cancellation in each band is input to the step size determining unit 15, and the step size determining unit 15 reflects the characteristics between the bands based on the amount of echo cancellation in each band. Is determined, the coefficient is updated while securing a certain level of the step size even in a band of a small level, so that echo cancellation can be performed in each band on average.

Embodiment 4 In the echo canceller shown in FIGS. 1, 2 and 3, the step size determining unit 15 is configured as shown in FIG.

The step size determining section 15 includes a band selecting section 150 and a step size table storage section 151.

The band selection section 150 receives the received signal level or residual signal level of each band, or the amount of echo cancellation, selects a band, for example, by selecting a band of the maximum value, and selects the band. Is output to the step size table storage unit 151.

The step size table storage section 151 stores
It has a plurality of tables for determining the step size of each band corresponding to the received signal level or residual signal level or the amount of echo cancellation, and one table is set according to the value of the input received signal level or residual signal level or the amount of echo cancellation. By selecting a table, the step size of each band is determined and output to the coefficient update units 71 to 7N of each band.

The above-mentioned step size table is a table of the step size of each band determined in advance by weighting reflecting characteristics between bands such as the characteristic of the audio signal that the audio signal is concentrated in the low frequency band. The step size of each band is determined in accordance with the corresponding received signal level or residual signal level or the amount of echo cancellation so as to obtain the step size of each band.

By configuring the step size determining unit 15 as described above, a table reflecting the received signal level or residual signal level of the selected band, or the value of the echo cancellation amount and the characteristic between the corresponding bands is obtained. The step size of each band is determined by selection, and even in a band of a small level, the coefficient is updated while securing a certain size in the step size, so that echo cancellation can be performed in each band on average.

Embodiment 5 FIG. Further, in the echo canceller shown in FIGS. 1, 2 and 3, the step size determining unit 15 is configured as shown in FIG.

The step size determining section 15 includes a band selecting section 150 and basic step size storing sections 1521 to 152.
N, and multipliers 1531 to 153N.

The band selecting section 150 receives the received signal level or residual signal level of each band or the amount of echo cancellation, selects a band which is a method of selecting a band of the maximum value, and selects the band. To the multipliers 1531 to 15
Output to 3N.

Multipliers 1531 to 153N calculate the step size of each band by multiplying the basic step size of each band held in each band basic step size storage unit 1521 to 152N by the value of the selected band. Are output to the coefficient update units 71 to 7N of the respective bands. The basic step size of each band is a value that is determined in advance by weighting that reflects characteristics between bands, such as characteristics of the audio signal that the audio signal has power concentrated in the low band.

By configuring the step size determination unit 15 as described above, the reception signal level or the residual signal level of the selected band, or the value of the echo cancellation amount and the basic characteristics of each band reflecting the characteristics between the bands. The step size of each band is determined by multiplying the step size by the step size. Even if a band of a small level is used, a certain size is secured for the step size and the coefficient is updated.

Embodiment 6 FIG. Embodiment 6 A band division echo canceller according to Embodiment 6 of the present invention will be described with reference to the drawings. FIG. 6 is a diagram showing a configuration of a band division echo canceller according to Embodiment 6 of the present invention.

In the echo canceller shown in FIG. 1, as shown in FIG.
A reception signal level calculator 14 is provided in addition to 1 to 14N.

The received signal level calculator 14 receives the received signal, calculates the level, and outputs the calculated level to the step size determiner 15.

The step size determination unit 15 calculates the reception signal level of the entire band and the reception signal level calculation unit 14 of each band.
The step size of each band reflecting the characteristics between the bands is determined based on the received signal level of each band calculated by 1 to 14N, and is output to the coefficient update units 71 to 7N of each band.

The coefficient update units 71 to 7N of the respective bands receive the received signals and residual signals of the respective bands, the step sizes of the respective bands determined by the step size determining unit 15, and the detection results of the double talk detecting unit 16. When the detection result of the double talk detecting unit 16 is not in the double talk state, the filter coefficients of the FIR filter units 51 to 5N of each band are updated using the above step size so that the residual echo included in the residual signal approaches zero. However, in the case of the double talk state, the coefficient is not updated.

As described above, the received signal level of the entire band and the received signal level of each band are input to the step size determining unit 15, and the step size determining unit 15 receives the received signal level of the entire band and the received signal level of each band. By determining the step size of each band by reflecting the characteristics between the bands based on the level, the coefficient is updated with a certain level of the step size even for a band of a small level. Echo cancellation is possible. Also, by using the received signal level of the entire band, it becomes possible to cope with a unique situation in which the level of the selected band instantaneously shows a very large ratio with respect to the received signal level of the entire band,
Further stable convergence is obtained.

Embodiment 7 Embodiment 7 A band-division echo canceller according to Embodiment 7 of the present invention will be described with reference to the drawings. FIG. 7 is a diagram showing a configuration of a band division echo canceller according to Embodiment 7 of the present invention.

In the echo canceller shown in FIG. 6, as shown in FIG. 7, the received signal level calculator 14 is replaced with the residual signal level calculator 17 and the received signal level calculators 141 to 14N of the respective bands are replaced. And residual signal level calculators 171 to 17N for each band.

The residual signal level calculator 17 receives the residual signal, calculates the level, and outputs the calculated level to the step size determiner 15.

Residual signal level calculators 171-1 of each band
7N also calculates the level of the residual signal in each band and outputs it to the step size determination unit 15. The step size determining unit 15 determines the step size of each band reflecting the characteristics between the bands based on the residual signal level of the entire band and the residual signal level of each band, and the coefficient updating unit 71 of each band. ~ 7
Output to N.

The coefficient update units 71 to 7N for each band receive the received signal and residual signal of each band, the step size of each band determined by the step size determination unit 15, and the detection result of the double talk detection unit 16. When the detection result of the double talk detecting unit 16 is not in the double talk state, the filter coefficients of the FIR filter units 51 to 5N of each band are updated using the above step size so that the residual echo included in the residual signal approaches zero. However, in the case of the double talk state, the coefficient is not updated.

As described above, the residual signal level of the entire band and the residual signal level of each band are input to the step size determining unit 15, and the step size determining unit 15 compares the residual signal level of the entire band with each band. By determining the step size of each band by reflecting the characteristics between the bands based on the residual signal level of, the coefficient is updated while securing a certain size in the step size even in a band of a small level. Echo cancellation can be performed on a band-average basis. Also, by using the residual signal level of the entire band, it is possible to cope with unusual situations where the level of the selected band instantaneously shows a very large ratio to the residual signal level of the entire band. Becomes
Further stable convergence is obtained.

Embodiment 8 FIG. Embodiment 8 A band division type echo canceller according to Embodiment 8 of the present invention will be described with reference to the drawings. FIG. 8 is a diagram showing a configuration of a band division echo canceller according to Embodiment 8 of the present invention.

In the echo canceller shown in FIG. 6, as shown in FIG. 8, in addition to the reception signal level calculation section 14 and the reception signal level calculation sections 141 to 14N of each band, a residual signal level calculation section 17 and each band Residual signal level calculator 1
71 to 17N and an echo cancellation amount calculation unit 18 are provided.

The received signal level calculator 14 receives the received signal, calculates the level, and outputs the calculated level to the echo cancellation amount calculator 18. In addition, the reception signal level calculation units 141 to 141 of each band
14N also calculates the level of the received signal in each band and outputs it to the echo cancellation amount calculation unit 18.

The residual signal level calculator 17 receives the residual signal, calculates the level, and outputs the calculated level to the echo cancellation amount calculator 18. Also, the residual signal level calculators 171 to 171 for the respective bands
17N also calculates the level of the residual signal in each band and outputs it to the echo cancellation amount calculation unit 18.

The echo cancellation amount calculator 18 receives the received signal level of the entire band, the received signal level of each band, the residual signal level of the entire band, and the residual signal level of each band. The residual signal level is divided by the received signal level, and the residual signal level of each band is divided by the received signal level to calculate the echo cancellation amount of the entire band and each band, and output to the step size determining unit 15. I do.

The step size determining unit 15 determines the step size of each band reflecting the characteristics between the bands based on the amount of echo cancellation of all the bands and the amount of echo cancellation of each band, and updates the coefficient of each band. Output to 71-7N. The coefficient update units 71 to 7N of each band receive the received signal and the residual signal of each band, the step size of each band determined by the step size determination unit 15, and the detection result of the double talk detection unit 16, and perform double talk. When the detection result of the detection unit 16 is not in the double talk state, the FI of each band is set using the above step size so that the residual echo included in the residual signal approaches zero.
The filter coefficients of the R filter units 51 to 5N are updated, and the coefficients are not updated in a double talk state.

As described above, the amount of echo cancellation for all bands and the amount of echo cancellation for each band are input to the step size determining unit 15, and the step size determining unit 15 cancels the amount of echo cancellation for all bands and the amount of echo cancellation for each band. By determining the step size of each band reflecting the characteristics between the bands based on the amount,
Even in a small-level band, the coefficient is updated while securing a certain size in the step size, so that echo cancellation can be performed in each band on average. Also, by using the echo cancellation amount of the entire band, it is possible to deal with unusual situations where the echo cancellation amount of the selected band instantaneously shows a very large ratio to the echo cancellation amount of the entire band. And more stable convergence is obtained.

Embodiment 9 FIG. In the echo cancellers shown in FIGS. 6, 7 and 8, the step size determining unit 15 is configured as shown in FIG.

The step size determining section 15 comprises a band selecting section 150, a step size table storage section 151, and a divider 154.

The band selection section 150 receives the received signal level or residual signal level of each band or the amount of echo cancellation, selects a band, for example, by selecting a band of the maximum value, and selects the band. Is output to the step size table storage unit 151 and the divider 154.

Divider 154 divides the level of the input band by the received signal level or residual signal level of the entire band, or the amount of echo cancellation to obtain the ratio of the level of the selected band to the level of the entire band, and stores it in a step size table. Output to the unit 151.

The step size table storage unit 151 stores
The step size of each band is determined according to both the received signal level or the residual signal level, or the amount of echo cancellation, and the ratio of those signals to the received signal level, the residual signal level, or the amount of echo cancellation of the entire band. Having a plurality of tables, the step size of each band is selected by selecting one table according to the input received signal level or residual signal level, or the value of the amount of echo cancellation and the ratio of those signals to the entire band. Is determined and output to the coefficient update units 71 to 7N of the respective bands.

The above-mentioned step size table is a table of the step size of each band determined in advance by weighting reflecting characteristics between bands such as characteristics of a voice signal that power is concentrated in a low frequency band. The corresponding received signal level or residual signal level, or the amount of echo cancellation, and the ratio of those signals to the entire band are determined so that the step size of each band reflecting its characteristics can be obtained.

By configuring the step size determining section 15 as described above, a table reflecting the received signal level or the residual signal level of the selected band or the value of the echo cancellation amount and the characteristic between the corresponding bands can be obtained. The step size of each band is determined by selection, and even in a band of a small level, the coefficient is updated while securing a certain size in the step size, so that echo cancellation can be performed in each band on average. Also, by using the ratio of the level of the selected band to the level of the entire band, it is possible to cope with a unique situation in which the level of the selected band instantaneously shows a very large ratio to the level of the entire band. It becomes possible and more stable convergence is obtained.

Embodiment 10 FIG. Further, in the echo canceller shown in FIGS. 6, 7 and 8, the step size determining unit 15 is configured as shown in FIG.

The step size determining section 15 includes a band selecting section 150 and basic step size storing sections 1521 to 152.
N, and multipliers 1531 to 153N and 155.

The band selection section 150 receives the received signal level or residual signal level of each band or the amount of echo cancellation, selects a band by a method such as selecting the band of the maximum value, and selects the band. Is output to the multiplier 155.

Multiplier 155 multiplies the level of the input band by the received signal level or residual signal level of the entire band or the amount of echo cancellation, and weights the level of the entire band to output to multipliers 1531 to 153N. .

The multipliers 1531 to 153N multiply the basic step size of each band held by the basic step size storage section 1521 to 152N of each band by the value of the selected band weighted with the level of all the bands. The band step size is calculated and output to the coefficient update units 71 to 7N of the respective bands. The basic step size of each band is a value that is determined in advance by weighting that reflects characteristics between bands, such as characteristics of the audio signal that the audio signal has power concentrated in the low band.

By configuring the step size determining unit 15 as described above, the received signal level or the residual signal level of the selected band, or the value of the amount of echo cancellation and the basic characteristics of each band reflecting the characteristics between the bands. The step size of each band is determined by multiplying the step size by the step size. Even if a band of a small level is used, a certain size is secured for the step size and the coefficient is updated. Also, by assigning the level of the selected band to the level of the entire band, it is possible to cope with a unique situation in which the level of the selected band instantaneously shows a very large ratio with respect to the level of the entire band. It becomes possible and more stable convergence is obtained.

Embodiment 11 FIG. Embodiment 1 of the present invention
1 will be described with reference to the drawings. FIG. 11 is a diagram showing a configuration of a band division echo canceller according to Embodiment 11 of the present invention.

In the echo canceller shown in FIG. 1, as shown in FIG. 11, the reception signal level calculator 1 for each band is used.
A reception signal level calculator 14 is provided instead of 41 to 14N.

The received signal level calculator 14 receives the received signal, calculates the level of the received signal by, for example, calculating the sum of the squares, and outputs the calculated level to the step size determiner 15.

The step size determining section 15 determines the step size of each band reflecting the characteristics between the bands based on the received signal level, and outputs it to the coefficient updating sections 71 to 7N of each band.

The coefficient update units 71 to 7N for each band receive the received signal and residual signal of each band, the step size of each band determined by the step size determination unit 15, and the detection result of the double talk detection unit 16. When the detection result of the double talk detecting unit 16 is not in the double talk state, the filter coefficients of the FIR filter units 51 to 5N of each band are updated using the above step size so that the residual echo included in the residual signal approaches zero. However, in the case of the double talk state, the coefficient is not updated.

As described above, the received signal level of the entire band is input to the step size determining section, and the step size determining section reflects the characteristics between the bands based on the received signal level of the entire band and reflects the step size of each band. Is determined, the coefficient is updated while securing a certain size in the step size even in a band of a small level, so that echo cancellation can be performed in each band on average.

Embodiment 12 FIG. Embodiment 1 of the present invention
2 will be described with reference to the drawings. FIG. 12 is a diagram showing a configuration of a band division echo canceller according to Embodiment 12 of the present invention.

In the echo canceller shown in FIG. 11, a residual signal level calculator 17 is provided instead of the received signal level calculator 14 as shown in FIG.

The residual signal level calculator 17 receives the residual signal, calculates the level, and outputs the calculated level to the step size determiner 15.

The step size determining section 15 determines the step size of each band reflecting the characteristics between the bands based on the residual signal level, and outputs the determined step size to the coefficient updating sections 71 to 7N of each band.

The coefficient update units 71 to 7N of each band receive the received signal and residual signal of each band, the step size of each band determined by the step size determination unit 15, and the detection result of the double talk detection unit 16. When the detection result of the double talk detecting unit 16 is not in the double talk state, the filter coefficients of the FIR filter units 51 to 5N of each band are updated using the above step size so that the residual echo included in the residual signal approaches zero. However, in the case of the double talk state, the coefficient is not updated.

As described above, the residual signal level of the entire band is input to the step size determining unit 15, and the step size determining unit 15 reflects the characteristics between the bands based on the residual signal level of the entire band. By determining the step size of each band, even in a band of a small level, the coefficient is updated while securing a certain size in the step size, so that echo cancellation can be performed in each band on average.

Embodiment 13 FIG. Embodiment 1 of the present invention
3 will be described with reference to the drawings. FIG. 13 is a diagram showing a configuration of a band division echo canceller according to Embodiment 13 of the present invention.

In the echo canceller shown in FIG. 11, a residual signal level calculator 17 and an echo cancellation amount calculator 18 are provided in addition to the received signal level calculator 14 as shown in FIG.

[0130] The received signal level calculator 14 receives the received signal, calculates the level, and outputs it to the echo cancellation amount calculator 18. Further, the residual signal level calculator 17 receives the residual signal, calculates the level, and outputs the calculated level to the echo cancellation amount calculator 18.

The echo canceling amount calculating section 18 receives the received signal level and the residual signal level, calculates the echo canceling amount by, for example, dividing the residual signal level by the received signal level, and determines the step size determining section. 15, the step size determination unit 15 determines the step size of each band based on the echo cancellation amount, and updates the coefficient update unit 71 of each band.
To 7N.

The coefficient update units 71 to 7N of each band receive the received signal and residual signal of each band, the step size of each band determined by the step size determination unit 15, and the detection result of the double talk detection unit 16. When the detection result of the double talk detecting unit 16 is not in the double talk state, the filter coefficients of the FIR filter units 51 to 5N of each band are updated using the above step size so that the residual echo included in the residual signal approaches zero. However, in the case of the double talk state, the coefficient is not updated.

As described above, the echo canceling amount of the entire band is input to the step size determining unit 15, and the step size determining unit 15 reflects the characteristics between the bands based on the echo canceling amount of the entire band. Is determined, the coefficient is updated while securing a certain level of the step size even in a band of a small level, so that echo cancellation can be performed in each band on average.

Embodiment 14 FIG. In the echo cancellers shown in FIGS. 11, 12 and 13, the step size determining unit 15 is configured as shown in FIG.

The step size determining section 15 is composed of a step size table storage section 151.

The step size table storage unit 151 stores
It has a plurality of tables for determining the step size of each band corresponding to the received signal level or residual signal level or the amount of echo cancellation, and one table is set according to the value of the input received signal level or residual signal level or the amount of echo cancellation. By selecting a table, the step size of each band is determined and output to the coefficient update units 71 to 7N of each band.

The above-mentioned step size table is a table of the step size of each band determined in advance by weighting that reflects characteristics between bands such as the characteristic of the audio signal that power is concentrated in the low frequency band. The step size of each band is determined in accordance with the corresponding received signal level or residual signal level or the amount of echo cancellation so as to obtain the step size of each band.

By configuring the step size determining section 15 as described above, a table reflecting the characteristic between the band corresponding to the value of the received signal level or the residual signal level, or the amount of echo cancellation, and selecting each table. Is determined, and even in a small-level band, the coefficient is updated while securing a certain size in the step size, so that echo cancellation can be performed in each band on average.

Embodiment 15 FIG. 11 and FIG.
In the echo canceller shown in FIG. 2 and FIG.
The step size determination unit 15 is configured as follows.

The step size determination section 15 includes basic step size storage sections 1521 to 152 N and a multiplier 1531.
~ 153N.

The multipliers 1531 to 153N multiply each of the basic step sizes of the respective bands held by the respective basic step size storage units 1521 to 152N by the received signal level or residual signal level, or the amount of echo cancellation. The band step size is calculated and output to the coefficient update units 71 to 7N of the respective bands.

The basic step size of each band is a value determined in advance by weighting reflecting characteristics between bands such as characteristics of the audio signal that the audio signal is concentrated in the low band.

By configuring the step size determining section 15 as described above, the received signal level or the residual signal level, or the value of the amount of echo cancellation is multiplied by the basic step size of each band reflecting the characteristics between the bands. By matching, the step size of each band is determined, and even in a band of a small level, the coefficient is updated while securing a certain size in the step size, so that echo cancellation can be performed in each band on average.

Embodiment 16 FIG. Embodiment 1 of the present invention
6 will be described with reference to the drawings. FIG. 16 is a diagram showing a configuration of a band division echo canceller according to Embodiment 16 of the present invention.

In the echo canceller shown in FIG. 11, as shown in FIG. 16, double talk detecting section 16 outputs the detection results to coefficient updating sections 71 to 7N and step size determining section 1
5 is output.

In the double talk state, the coefficient updating unit 71
7N are controlled not to perform the update operation, and the step size determination process may be stopped.
The step size determination unit 15 includes a double talk detection unit 16
When the detection result is not in the double talk state, the step size of each band is determined, and in the case of the double talk state, the step size determination processing of each band is not performed. This allows
In the case of the double talk state, the processing can be reduced.

Also, the echo cancellers shown in FIGS. 1, 2, 3, 6, 7, 8, 12, and 13 can be reduced in processing by the same method.

Embodiment 17 FIG. Embodiment 1 of the present invention
7 will be described with reference to the drawings. FIG. 17 is a diagram showing a configuration of a band division echo canceller according to Embodiment 17 of the present invention.

In the echo canceller shown in FIG. 11, a clipping circuit 156 is provided as shown in FIG. 17, and the determined step size of each band is inputted. If it is 1 or more, clip to 1.

As a result, it is guaranteed that the step size of each band is a value within the range of conditions for performing stable adaptive operation of the echo canceller, and is a value that also takes into account the amount of echo cancellation and the convergence time. .

Also, the echo cancellers shown in FIG. 1, FIG. 2, FIG. 3, FIG. 6, FIG. 7, FIG. 8, FIG. This is a value within the range of conditions for performing the adaptive operation described above, and is a value that also takes into account the amount of echo cancellation and the convergence time.

Embodiment 18 FIG. Embodiment 1 of the present invention
8 will be described with reference to the drawings. FIG. 18 is a diagram showing a configuration of a band division echo canceller according to Embodiment 18 of the present invention.

In the echo canceller shown in FIG. 11, the step size monitoring unit 15 as shown in FIG.
7 and input the determined step size of each band,
When the input step size exceeds the set threshold value, control is performed so as not to update the coefficient.

Thus, the coefficient update can be stopped, for example, when the step size is very close to zero, so that the processing can be reduced.

Further, the echo cancellers shown in FIG. 1, FIG. 2, FIG. 3, FIG. 6, FIG. 7, FIG. 8, FIG.

Embodiment 19 FIG. Embodiment 1 of the present invention
9 will be described with reference to the drawings. FIG. 19 is a diagram showing a configuration of a band division echo canceller according to Embodiment 19 of the present invention.

In the echo canceller shown in FIG. 11, a difference monitor 158 is provided as shown in FIG.
Received signal, or received signal of each band, or residual signal,
Or input the signal which determines the step size such as the residual signal of each band, or the amount of echo cancellation, or the amount of echo cancellation of each band, and take the difference from the previous sample respectively,
For samples whose difference exceeds a set threshold, the step size determination unit 15 is controlled so that the step size of each band is not changed and the previous step size is maintained.

Thus, it is possible to prevent the step size from increasing following a unique situation in which the level of each signal instantaneously increases.

Also, in the echo cancellers shown in FIG. 1, FIG. 2, FIG. 3, FIG. 6, FIG. 7, FIG. 8, FIG. 12, and FIG. It is possible to prevent the step size from increasing in accordance with such an unusual situation.

Embodiment 20 FIG. In the echo canceller shown in FIG. 19, the threshold provided in the difference monitoring unit 158 is updated by the residual signal level. As a result, the control can be changed between a state where the residual signal level of the echo canceller has just started to converge is large and a state where the residual signal level is converged is small.

Embodiment 21 FIG. Also, in the echo canceller shown in FIG.
The processing is reduced by performing the step size determination processing in a plurality of times once. Further, the processing of the echo cancellers shown in FIGS. 2, 3, 6, 7, 8, 11, 12, and 13 can be reduced by the same method.

[0162]

As described above, the band-division echo canceller according to the present invention has an effect that, by updating the step size for each band, the echo can be canceled on average in each band.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a band division echo canceller according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing a configuration of a band division echo canceller according to Embodiment 2 of the present invention.

FIG. 3 is a diagram showing a configuration of a band division echo canceller according to Embodiment 3 of the present invention.

FIG. 4 is a diagram showing a configuration of a step size determining unit of a band division echo canceller according to Embodiment 4 of the present invention.

FIG. 5 is a diagram showing a configuration of a step size determining unit of a band division echo canceller according to Embodiment 5 of the present invention.

FIG. 6 is a diagram showing a configuration of a band division echo canceller according to Embodiment 6 of the present invention.

FIG. 7 is a diagram showing a configuration of a band division echo canceller according to Embodiment 7 of the present invention.

FIG. 8 is a diagram showing a configuration of a band division echo canceller according to an eighth embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of a step size determining unit of a band division echo canceller according to Embodiment 9 of the present invention.

FIG. 10 is a diagram showing a configuration of a step size determining unit of a band division echo canceller according to Embodiment 10 of the present invention.

FIG. 11 is a diagram showing a configuration of a band division echo canceller according to Embodiment 11 of the present invention.

FIG. 12 is a diagram showing a configuration of a band division echo canceller according to Embodiment 12 of the present invention.

FIG. 13 is a diagram showing a configuration of a band division echo canceller according to Embodiment 13 of the present invention.

FIG. 14 is a diagram showing a configuration of a step size determining unit of a band division echo canceller according to Embodiment 14 of the present invention.

FIG. 15 is a diagram showing a configuration of a step size determining unit of a band division echo canceller according to Embodiment 15 of the present invention.

FIG. 16 is a diagram showing a configuration of a band division echo canceller according to Embodiment 16 of the present invention.

FIG. 17 is a diagram showing a configuration of a band division echo canceller according to Embodiment 17 of the present invention.

FIG. 18 is a diagram showing a configuration of a band division echo canceller according to Embodiment 18 of the present invention.

FIG. 19 is a diagram showing a configuration of a band division echo canceller according to Embodiment 19 of the present invention.

FIG. 20 is a diagram showing a configuration of a conventional echo canceller.

FIG. 21 is a diagram showing a configuration of another conventional echo canceller.

FIG. 22 is a diagram illustrating a configuration of a conventional band-division echo canceller.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 reception signal input terminal, 2 reception signal output terminal, 3 transmission signal input terminal, 4 transmission signal output terminal, 5 FIR filter unit, 501 reception signal register, 502 coefficient register, 503 accumulator, 51 band 1 FIR filter unit , 5N FIR filter section of band N, 6 subtractor, 6
1 band 1 subtractor, 6N band N subtractor, 7a, 7
b coefficient update unit, 701 square sum operation circuit, 702 correction circuit, 7021 band 1 step size determination unit, 7
02N Step size determination unit for band N, 703 correction value generation circuit, 704 coefficient update circuit, 705 step size control circuit, 71 band 1 coefficient update circuit, 7N
Band N coefficient update circuit, 11 Reception-side band division filter, 12 Transmission-side band division filter, 13 Band synthesis filter, 14 Received signal level calculation unit, 141 Band 1
Received signal level calculator, 14N band N received signal level calculator, 15 step size determiner, 150 band selector, 151 step size table storage, 1
521 Band 1 basic step size storage, 152N
Basic step size storage unit for band N, 1531 multiplier for band 1, 153N multiplier for band N, 154 divider, 155 multiplier, 156 clip circuit, 157
Step size monitor, 158 difference monitor, 16 double talk detector, 17 residual signal level calculator, 171
Band 1 residual signal level calculator, 17N Band N residual signal level calculator, 18 echo cancellation amount calculator.

Claims (24)

[Claims] 1. A receiving-side band division filter for dividing a received signal, and a FIR filter of each band for performing a convolution operation of the divided received signal and a filter coefficient of each band to synthesize a pseudo echo signal of each band. A transmission-side band division filter that divides a transmission signal; a subtractor of each band that subtracts the pseudo echo signal of each band from the divided transmission signal to calculate a residual signal of each band; A band synthesis filter for synthesizing a residual signal of a band, a reception signal level calculation unit that receives a reception signal and calculates a level thereof, and a step size determination unit that determines a step size of each band based on the reception signal level, A double-talk detector that detects double-talk based on the reception signal, the transmission signal, and the residual signal; When not in the BullTalk state, based on the received signal of each band, the residual signal of each band, and the step size of each band determined by the step size determining unit, the residual echo included in the residual signal approaches zero. And a coefficient updating unit for each band for updating a filter coefficient of the FIR filter unit for each band. 2. The reception signal level calculation unit of each band, wherein the reception signal level calculation unit calculates a level of a reception signal of each band divided by the reception side band division filter. 2. The band-division echo canceller according to 1. 3. The reception signal level calculation unit includes: a reception signal level calculation unit for calculating a reception signal level of each band divided by the reception-side band division filter; 2. A band-division echo canceller according to claim 1, wherein said echo canceller is a received signal level calculator for calculating the level of a received signal in a band. 4. The reception signal level calculation means according to claim 1, wherein said reception signal level calculation means is a reception signal level calculation section for calculating the level of a reception signal in a whole band from a reception signal input terminal.
The described band splitting echo canceller. 5. The step size determination unit, wherein the step size determination unit has a plurality of step sizes of each band as a table, selects one table corresponding to an input received signal level, and determines a step size of each band. The band-division echo canceller according to any one of claims 1 to 4, further comprising a storage unit. 6. The step size determination unit includes a basic step size storage unit for each band having a basic step size for each band, and a multiplication of each band for multiplying an input received signal level by the basic step size for each band. The band-division echo canceller according to any one of claims 1 to 4, further comprising a filter. 7. A reception-side band division filter for dividing a reception signal, and a FIR filter for each band for performing a convolution operation of the divided reception signal and a filter coefficient for each band to synthesize a pseudo echo signal of each band. A transmission-side band division filter that divides a transmission signal; a subtractor of each band that subtracts the pseudo echo signal of each band from the divided transmission signal to calculate a residual signal of each band; A band synthesis filter for synthesizing the residual signal of the band, a residual signal level calculating means for inputting the residual signal and calculating the level, and a step size determining for determining a step size of each band based on the residual signal level A double-talk detector that detects double-talk based on the reception signal, the transmission signal, and the residual signal; and a detection result of the double-talk detector. When not in the BullTalk state, based on the received signal of each band, the residual signal of each band, and the step size of each band determined by the step size determining unit, the residual echo included in the residual signal approaches zero. And a coefficient updating unit for each band for updating a filter coefficient of the FIR filter unit for each band. 8. The residual signal level calculating section is a residual signal level calculating section for each band for calculating a level of a residual signal for each band divided by the transmitting side band dividing filter. The band-division echo canceller according to claim 7, wherein 9. The residual signal level calculating unit for calculating a residual signal level of each band divided by the transmitting side band dividing filter, the residual signal level calculating unit for each band, and the band synthesizing filter. The band-division echo canceller according to claim 7, characterized in that it is a residual signal level calculator for calculating the level of the residual signal in all bands from the subband. 10. The band according to claim 7, wherein said residual signal level calculating means is a residual signal level calculating section for calculating the level of the residual signal of the entire band from said band synthesis filter. Split echo canceller. 11. The step size determination unit has a plurality of step sizes of each band as a table, selects one table corresponding to the input residual signal level, and determines a step size of each band. The band-division echo canceller according to any one of claims 7 to 10, further comprising a table storage unit. 12. The step size determining unit includes: a basic step size storage unit for each band having a basic step size for each band; and a basic step size storage unit for each band for multiplying the input residual signal level by the basic step size for each band. The band-division echo canceller according to any one of claims 7 to 10, further comprising a multiplier. 13. A receiving-side band division filter for dividing a reception signal, and a FIR filter for each band for performing a convolution operation of the divided reception signal and a filter coefficient for each band to synthesize a pseudo echo signal for each band. A transmission-side band division filter that divides a transmission signal; a subtractor of each band that subtracts the pseudo echo signal of each band from the divided transmission signal to calculate a residual signal of each band; A band synthesis filter for synthesizing a residual signal of a band, a reception signal level calculation means for inputting a reception signal and calculating the level, a residual signal level calculation means for inputting a residual signal and calculating the level, An echo canceling amount calculating unit that calculates an echo canceling amount of each band based on a received signal level and the residual signal level; and a step of each band based on the echo canceling amount of each band. A step size determining unit that determines a noise, a double talk detecting unit that detects double talk based on the received signal, the transmitting signal, and the residual signal; and a case where a detection result of the double talk detecting unit is not in a double talk state. Based on the received signal of each band, the residual signal of each band, and the step size of each band determined by the step size determining unit, such that the residual echo included in the residual signal approaches zero. And a coefficient updating unit for each band for updating the filter coefficient of the FIR filter unit. 14. The reception signal level calculation unit, wherein the reception signal level calculation unit is a reception signal level calculation unit for each band that calculates a level of a reception signal of each band divided by the reception-side band division filter. 14. The band division echo according to claim 13, wherein the means is a residual signal level calculation unit for each band that calculates a level of a residual signal of each band divided by the transmission side band division filter. Canceller. 15. The reception signal level calculation unit includes: a reception signal level calculation unit for calculating a reception signal level of each band divided by the reception-side band division filter; A reception signal level calculation unit that calculates a level of a reception signal of a band, wherein the residual signal level calculation unit calculates a level of a residual signal of each band divided by the transmission-side band division filter. 14. The band division echo canceller according to claim 13, further comprising: a residual signal level calculator, and a residual signal level calculator for calculating a level of a residual signal of the entire band from the band synthesis filter. 16. The reception signal level calculation unit is a reception signal level calculation unit that calculates a level of a reception signal in a whole band from a reception signal input terminal, and the residual signal level calculation unit is configured to use the band synthesis filter. The band-division echo canceller according to claim 13, characterized in that it is a residual signal level calculator for calculating the level of the residual signal in all bands from the subband. 17. The step size determination unit, wherein the step size determination unit has a plurality of step sizes of each band as a table, selects one table corresponding to the input amount of echo cancellation, and determines the step size of each band. 17. The band division echo canceller according to claim 13, further comprising a storage unit. 18. The method according to claim 18, wherein the step size determining unit is configured to store a basic step size of each band having a basic step size of each band, and to multiply each band by multiplying the input echo cancellation amount by the basic step size of each band. 17. The band-division echo canceller according to claim 13, further comprising a filter. 19. The double talk detecting unit outputs a detection result to the step size determining unit, and the step size determining unit determines a step size of each band when the detection result is not in a double talk state. 19. The band splitting echo canceller according to claim 1, wherein the band splitting type echo canceller operates and stops a step size determination process for each band when in a double talk state. 20. Further, the determined step size of each band is input, and the value is set to 0.
2. A clip circuit for clipping to 0 when the value is 1 or less and 1 when the value is 1 or more.
8. The band-divided echo canceller according to any one of 8. 21. A step size monitoring unit for inputting the determined step size of each band and controlling not to update the coefficient when the input step size exceeds a set threshold value. 19. The method according to claim 1, wherein:
The band-division echo canceller according to any of the above. 22. Further, a received signal, a residual signal, or an echo canceling amount is input to obtain a difference from the preceding sample, and for a sample whose difference exceeds a set threshold, the step size of each band is set. 19. The band division echo canceller according to claim 1, further comprising a difference monitoring unit that controls the step size determination unit so as to retain the previous step size without changing the same. . 23. The apparatus according to claim 22, wherein the difference monitoring unit updates the threshold with a residual signal level.
The described band splitting echo canceller. 24. The band-division echo canceller according to claim 1, wherein the step size determining unit performs the step size determining process once in a plurality of times.