JPS62154925A - H register nonvolatile type echo canceler - Google Patents

Abstract

PURPOSE:To hold an impulse response even after power-off operation and to eliminate the need for training after the power source is turned on again by providing a power source monitor circuit, a pattern generator, a switch, and a nonvolatile storage circuit. CONSTITUTION:Even when the power source of an echo canceler device is turned off, the contents of an H register can be held in the nonvolatile storage circuit consisting of a RAM 30 and a backup battery 35. When the power source is turned on, the contents of the H register stored in the nonvolatile storage circuit are stored in the echo canceler. Consequently, calling is enable without the training of an echo canceler 40 due to a white noise after the power-on operation.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an acoustic echo canceller device that does not require I-learning due to Why I noise, etc. when power is turned on, and particularly relates to an acoustic echo canceller device that does not require I-learning due to Why I noise etc. when power is turned on. The present invention relates to non-volatile content of the H register of the echo canceller main body.

[Conventional technology]

In the acoustic echo canceller, the -r-coe path x is constant, but since the number of taps is long, it takes a long time for the in/L/s response of the knee-go path to converge. Therefore, in order to train the echo canceller when the power is turned on, it is necessary to send white noise or the like from the receiving side input (Rin) to the receiving side output (Rout).

[Problem that the invention seeks to solve]

Training the echo canceller using white noise, etc. as described above takes time because the number of taps in the echo canceller is long, and due to the nature of the echo canceller, during training, a signal other than white noise for training is given to the acoustic path. There are constraints during training that reduce the effectiveness of training. Furthermore, since the contents of the H register are erased when the power is turned off, there is a drawback that white noise, etc. for training must be sent out again when the power is turned on.

SUMMARY OF THE INVENTION An object of the present invention is to provide an echo canceller device that retains the impulse response even after power is turned off and does not require training after power is turned on again.

[Means for solving problems]

According to the present invention, in an echo canceller device having an echo canceller having an H register.

1. A power supply monitoring circuit that monitors the power supply of the echo canceller device and outputs a detection signal when the power supply is cut off;
, a pattern generator that, upon receiving the detection signal, sends a predetermined pattern of signals to the receiving input of the echo canceller; and a switch that responds to the predetermined pattern of signals and grounds the transmitting input of the echo canceller. and a non-volatile memory circuit for storing the contents of the H register 1) taken out to the transmitting side output of the echo can in response to the predetermined turn signal. (A register non-volatile echo canceller device is obtained.

〔Example〕

Next, two aspects of the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a diagram showing the principle of the echo canceller in FIG. 1.

As shown in Figure 2, in the acoustic field, an echo is generated when the outgoing signal returns via the return path due to the acoustic coupling between the speaker 50 and the micro 0, so the impulse response of the echo path is It is an illusion that the echo can be canceled by estimating the surface.

Now, as shown in Fig. 2, the input signal to the receiving side human power R1n is input to
If the input signal to in and the noise are VG□, and the in-gus response of echo-gus is hω, the return signal is 'Yoa
”= h5.> X Therefore, the echo cancellation residual can be expressed by the following equation.

△ e(k) ``y(k)''(k)
(3) Set the number of echo canceller taps to N
If it is , then (2) is obtained. This is the estimated echo.

Adaptive control by sequentially correcting the coefficient h(k) of the tap, which is currently commonly used, is performed at time 9, assuming that the coefficient of the n-th tap is hn(k).

”n (k+1) −hn(k)+Δh n(k)
(5) α: Correction gain (0 x α x 2).

An embodiment of the present invention will now be described below, assuming that the number of taps in the echo canceller is three.

Since the number of taps N of the echo canceller is 3, "(k)"
"0 (k) ゛Smell+h+(k)"(k-1)-h2
(k) 'X(k-2) (7)ho(k-1)
−ho(k)+Δh(k) ”X(k)
(9) hl(k+1)=hl(k)+”(
k) 'x(k-1) ``h2(k+1)
:h2(k)+ha(k)°X(k-2) θ
It becomes υ.

In FIG. 1, when the power supply monitoring circuit 1o detects the cutoff of the power supply to the echo canceller device, it sends the signal shown below from the gloss turn generator 20 to the receiving side human power R1n of the echo canceller.

Intestines
-Time (k) 1 2 3 4
When k) to s sending signal is "1" or later (time is 3 or later),
When the switch 25 is turned on, y(3) = O and Narnote, from equation (7), y(3) = ho(s)"+h1(3)"+hz(s)"
=ho(s) (n(3) formula: 0(3)=y(3) '(3)= ”(3) = −
h. (3) ("1, the formula (8) is Jh (3) = - to 3 stops □ α→, and the formula (9) ~ α9 is ho (4) = ho (3) - α' hO(5)”
α0h1(4) = hl(3)−α'
ho(3) '0=hl(3) αQh2
(4) ""hz(3)-α'ho(3)" =
hz(3) becomes α. (7) Formula and α→
~ According to the alpha formula.

'(4) "" hO(3)・O+ hl(3) 4
+hz(3) -0=hl(5)
(1 o'clock -e(4)"""(4
) −”(4)=0−hl(3)=−hl3)
It becomes α groan. Similarly, y(5>=hz(3)
"e(s) = -hz(3)
H can be obtained.

From equations (to), (to), and (c), echo canceller 40
The transmitter output S. From ut -e(3) ”(4) ,”
(s) is stored in the RAM 30 supplied with power by the backup battery 35, and stored in the H register of the echo canceller. (3) ,”1(
3) , hz (3) can be maintained when the power is turned off. In other words, it becomes possible to make the register itself non-volatile.

Next, in FIG. 1, when the power supply monitoring circuit 10 detects that the echo canceller device is powered on, the return generator 20 and the RAM 30 are connected to the receiving side input R1n and the transmitting side input Sin of the echo canceller 4o, respectively. send a signal indicating At this time.

At time 1.2, switch 25 is not ON.

From then on, the transmitter side of the echo canceller 4o
A signal is sent to RAM 30.

Time k 123456 → 00hoh1h2 Signal from RAM (k) When the H register of echo canceller 4o is cleared when the power is turned on, according to equation (7), y(3) = O・α+0・o+o・0=0
Kan and Nashi.

e(3) = y(3) -y(3) = ho-0=
ho @ From formula (8).

α・hh ”(s) = 1 “−7−(goods). Therefore, from (9) to α formula, ho− ho(4) −〇+α−, −hoH h, (4) = 0 + O・su=0 (c)hz(4)=0+0・,=o@.

From equation (7), y(4) is y(4)=ho・0+0・α+0・0=0 (
C) Next.

e(4) = y(4) Y(a) ≧ circle = h1
0=h1el)i From formula (8).

“°5.
) below margin hl(5)=0+α・hill=h10■ α h2(5)=o+o-! LL= o
It becomes e3'1α.

From equation (7), Hinoki (cypress) becomes y(5)=ho・0+ho+o・α=004.

e(5)=y(5)-y(5)=h2-O-h2e:!
From formula 4(8).

Therefore, (9) ~ α ■ formula, ho (6) = ho + 0・-22 − = ho
oihl(6)=h1+0・τ−h1
(to) h2(/,)=0+α・−=h20Iα and so on, and is stored in the RAM 30 at time 6. "1" and "2" are stored in the H register of the echo canceller 4o.

〔Effect of the invention〕

As described above, in the present invention, even if the power to the echo canceller device is cut off, the non-volatile memory circuit consisting of the RAM 30 and the backup battery 35 remains intact.

The contents of the H register can be held. ′-! ,Ta.

When the power is turned on, the contents of the H register stored in the nonvolatile memory circuit are stored in the echo canceller, so it is possible to make a call without having to train the echo canceller with white noise after the power is turned on.

[Modified example]

In addition to the non-volatile memory circuit consisting of the RAM 3Q and the backup battery 35, for example, an EP-ROM (erasable programmable ROM) may be used as the non-volatile memory circuit.
) can be used.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a diagram showing the principle of an echo canceller. In Fig. 1, 9.10...power supply monitoring circuit, 20...
- Pattern generator, 25... control switch. 30...RAM, 35...Backup battery. 40...Echo canceller. Ko

Claims (1)

[Claims] 1. In an echo canceller device having an echo canceller having an H register, a power supply monitoring circuit that monitors the power supply of the echo canceller device and outputs a detection signal when the power supply is cut off; and upon receiving the detection signal, a pattern generator for transmitting a predetermined pattern of signals to a receiving input of the echo canceller; a switch responsive to the predetermined pattern of signals to ground a transmitting input of the echo canceller; An H-register non-volatile echo canceller device comprising: a non-volatile memory circuit for storing the contents of the H-register taken out to a transmitting side output of the echo canceller.