JPS6096037A - Echo canceller - Google Patents

Abstract

PURPOSE:To attain the detection of superimposed call even when a superimposed signal is lower than an echo signal in level and an echo signal level is low by using an output level rather than an input level to detect the level of the transmission side signal. CONSTITUTION:An attenuation measuring circuit 10 obtains the sum of the echo loss and the echo cancelling amount based on the outputs of two measuring circuit 8, 9 (the value is obtained from the ratio of the reception side signal level to the remaining erasure echo level). A reception signal level estimation value operating circuit 11 obtains an estimate value of the reception signal level from the level of the measured attenuation and the remaining erasure echo level measured by the attenuation measuring circuit 10 (obtained by multiplying both the levels). The estimate value and the value whose level is measured by a reception signal level estimate section 9 are compared by a comparator circuit 12. The decrease in the echo cancelling amount is prevented due to correction, stop or correcting speed reduction of an echo path model of the echo cancelling section by using the comparator output.

Description

【発明の詳細な説明】 本発明は通信回路における反響を除去する反響制御装置
に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an echo control device for eliminating echoes in a communication circuit.

従来長距離回線、拡戸電話機、双方向中継器などの反響
を制御するために反響阻止装置、音声スイッチ、反響消
去装置などが用いられている。これらのうち前の２つは
回線をオン・オフするための話頭切断やクリック雑音等
の障害が発生するという問題を有しておシ、あとの反響
消去装置は前記のような反響阻止装置や音声スイッチの
欠点を補うために開発されたものである。この装置は反
響路の測定を行ない、測定された反響路特性をもとに反
響信号と近似的な近似反響信号を合成し、これにより実
際の反響信号を消去するもので、話頭切断、クリック雑
音等の障害の原因となる機構は有していない。Conventionally, echo blocking devices, voice switches, echo canceling devices, etc. have been used to control echoes from long-distance lines, door extension telephones, two-way repeaters, etc. The first two of these have problems such as disconnection at the beginning of the line and click noise when turning the line on and off, and the second echo canceling device uses the echo blocking device and other devices described above. It was developed to compensate for the drawbacks of voice switches. This device measures the echo path, synthesizes the echo signal and an approximate echo signal based on the measured echo path characteristics, and thereby eliminates the actual echo signal, resulting in cutting off the beginning of speech and clicking noise. It does not have a mechanism that causes such problems.

しかしこの反響消去装置の場合、その基本構成において
は、反響信号に送話信号、雑音等が重畳して送話側入力
に入力してきた時に反響路の測定精度が低下し、また反
響消去量も送話側入力の反響信号と他の信号レベルの比
で定まる値まで低下する素因を有している。そこでこの
重畳状態での反響消去量の低下を防ぐために実際には従
来から重畳通話の検出回路が用いられている。しかしこ
の重畳通話の検出は受話側信号レベルと送話側レベルを
比較して行なっているため、反響信号レベルに対し重畳
信号レベルが小さい時の検出または反響信号レベルの小
さい時の重畳通話の検出は不可能という欠点を有してい
た。However, in the case of this echo cancellation device, in its basic configuration, when the echo signal is superimposed with the transmission signal, noise, etc. and input to the transmission side input, the measurement accuracy of the echo path decreases, and the amount of echo cancellation decreases. It has a predisposition to decrease to a value determined by the ratio of the echo signal level of the transmitting side input to the other signal level. Therefore, in order to prevent the amount of echo cancellation from decreasing in this superimposed state, a superimposed speech detection circuit has been used in practice. However, since this superimposed call detection is performed by comparing the receiving side signal level and the sending side signal level, it is detected when the superimposed signal level is smaller than the echo signal level, or when the echo signal level is small, the superimposed call is detected. had the disadvantage of being impossible.

したがって本発明の目的は、反響信号レベルに対し重畳
信号レベルが小さい時および反響信号レベルが小さい時
にも重畳通話の検出を可能とし、反脅消去擬の低下を防
ぐことのできる反響消去装置を提供するにある。Therefore, an object of the present invention is to provide an echo cancellation device that can detect a superimposed call even when the superimposed signal level is small relative to the echo signal level and when the echo signal level is small, and can prevent a decrease in anti-threat cancellation. There is something to do.

本発明は上記の目的を達成するために送話側信号のレベ
ルを検出するのに入力レベルではなく出力レベルにおい
て行うようにし、これに伴って必要な回路を附加するよ
うにしたものである。In order to achieve the above object, the present invention detects the level of the transmitter signal at the output level rather than at the input level, and accordingly adds necessary circuitry.

本発明によれば、反響路の入出力信号より反響路の特性
全測定し、得られた反響路特性に基づき近似反響路信号
を合成することにより実際の反響信号の消去を行なう反
響消去装置において、受話残信号レベルを測定する受話
信号レベル測定回路。According to the present invention, there is provided an echo cancellation device that measures all the characteristics of the echo path from the input/output signals of the echo path and cancels the actual echo signal by synthesizing an approximate echo path signal based on the obtained echo path characteristics. , a received signal level measurement circuit that measures the remaining received signal level.

受話信号レベルを推定する受話信号レベル推定部。A received signal level estimator that estimates a received signal level.

および前記受話信号レベル測定回路と前記受話信号レベ
ル推定部の出力レベルを比較する比較部を有し、この比
較部の出力によシ前記反響路の特性を測定する動作を制
御するようにしたことを特徴とする反響消去装置が得ら
れる。and a comparison section that compares the output levels of the reception signal level measuring circuit and the reception signal level estimation section, and the operation of measuring the characteristics of the echo path is controlled by the output of the comparison section. An echo canceling device is obtained which is characterized by:

次に図面を参照して本発明につき詳細に説明する０ 図は本発明の一実施例の回路構成をブロックで示した図
であり、この場合長距離回線に使用に適しているのを示
している。第１図において、１゜２．３および４は受話
人力、受話出力、送話人力および送話出力の端子をそれ
ぞれあられしている。Next, the present invention will be explained in detail with reference to the drawings. The figure is a block diagram showing the circuit configuration of an embodiment of the present invention, and in this case, it is shown that it is suitable for use in a long-distance line. There is. In FIG. 1, 1°2.3 and 4 denote terminals for the receiver's power, the receiver's output, the transmitter's power, and the transmitter's output, respectively.

反響消去部５は従来の反響消去装置にも使用されている
ので、減算回路６と近似反響信号合成回路７から構成さ
れている。そして受話側信号は従来と同じく受話側信号
レベル測定回路９でレベル測定されるが、送話側の信号
は従来と異って減算回路６の送話出力側の消去残エコー
か消去残信号レベル測定器８でレベル測定される。Since the echo canceller 5 is also used in conventional echo cancelers, it is comprised of a subtraction circuit 6 and an approximate echo signal synthesis circuit 7. Then, the level of the receiving side signal is measured by the receiving side signal level measuring circuit 9 as in the conventional case, but unlike the conventional case, the level of the transmitting side signal is measured by the canceled residual echo or the canceled residual signal level on the sending output side of the subtraction circuit 6. The level is measured by a measuring device 8.

減衰量測定回路１０は前記２つの測定回路８と９の出力
を基にして反響路損失と反響消去量の和をめる（この値
は受話側信号レベルと消去残エコーレベルの比によりま
る）。すなわち、ノ・イブリッド回路１４から端子３に
到るまでの損失特性をＬＡ（反響路損失）とし、端子３
から測定回路８までの損失特性をＬＢ（反響消去量）と
すると、受話（ｇ号几と残差エコー信号ｅとの関係はｅ
　＝　ＬＡ　ｅ　ＬＢ　・Ｒ として表わされる。従って、受話信号Ｒが入力される端
子２から測定回路８までの損失特性は、■で表わされる
。この値は重畳信号の無いときけ常に増加しているが、
重畳信号が有るときは重畳信号と消去残信号の和となり
、あたかも消去残エコーが増加したかのように見え、結
果的に反響路損失と反響消去量の和が減少したものと間
違って受けとれる。この重畳信号による誤動作を防ぐた
めに、減衰量測定回路１０は減衰量の埴として前同使用
した値と今回測定した値とを比較し、大きな方の値を用
いる。但しこの減衰量の値を時間と共に小さくすると装
置の安定性が良く成る。The attenuation measurement circuit 10 calculates the sum of the echo path loss and the amount of echo cancellation based on the outputs of the two measurement circuits 8 and 9 (this value depends on the ratio of the receiving side signal level and the cancellation residual echo level). . In other words, the loss characteristic from the no-bridder circuit 14 to the terminal 3 is defined as LA (echo path loss),
If the loss characteristic from to the measurement circuit 8 is LB (echo cancellation amount), then the relationship between the reception (g) and the residual echo signal e is expressed as e.
= LA e LB ·R. Therefore, the loss characteristic from the terminal 2 to which the reception signal R is input to the measurement circuit 8 is represented by ■. This value always increases when there is no superimposed signal, but
When there is a superimposed signal, it becomes the sum of the superimposed signal and the cancellation residual signal, and it appears as if the cancellation residual echo has increased, which can be mistakenly interpreted as a decrease in the sum of the echo path loss and the amount of echo cancellation. . In order to prevent malfunctions due to this superimposed signal, the attenuation measuring circuit 10 compares the previously used value and the currently measured value as the attenuation value, and uses the larger value. However, if the value of this attenuation amount is decreased over time, the stability of the device will improve.

受話信号レベル推定値演算回路１１は減衰量測定回路１
０で測定された減衰量のレベルと消去残エコーレベルと
から受話信号レベルの推定値をめる（両レベルの乗算に
よりまる）。この推定値と受話信号レベル推定部９によ
りレベル測定された値とを比較回路１２により比較する
と、重畳信号のあるときは上記のように消去残エコーレ
ベル測定回路８の信号レベルが大きくなるため、受話信
号レベル推定値演算回路１１の出力に対し受話信号レベ
ル測定回路９の値が小さくなる。この比較器出力により
反響消去部５の反響路モデルの修正、停止又は修正速度
低下により反響消去量の低下を防ぐことができる。また
比較回路１２によシ比較する時受話信号レベル測定部９
または受話信号推定値に定数を加えることにより動作の
安定化がはかれる。なお本装置においては消去残エコー
レベル測定回路８と筏状量測定回路１０と受話信号レベ
ル推定値演算回路１１とを合せて受話信号レベル推定部
１３と名付けてよい。The received signal level estimated value calculation circuit 11 is the attenuation measurement circuit 1
The estimated value of the received signal level is calculated from the level of the attenuation amount measured at 0 and the level of the canceled residual echo (determined by multiplying both levels). Comparing this estimated value with the level measured by the received signal level estimating section 9 using the comparing circuit 12, it is found that when there is a superimposed signal, the signal level of the canceled residual echo level measuring circuit 8 increases as described above. The value of the received signal level measurement circuit 9 becomes smaller than the output of the received signal level estimated value calculation circuit 11. This comparator output can prevent a decrease in the amount of echo cancellation by modifying, stopping, or slowing down the modification speed of the echo path model of the echo canceller 5. Also, when comparing using the comparator circuit 12, the receiving signal level measuring section 9
Alternatively, the operation can be stabilized by adding a constant to the estimated received signal value. In this device, the canceled residual echo level measuring circuit 8, the raft-shaped amount measuring circuit 10, and the received signal level estimated value calculation circuit 11 may be collectively named the received signal level estimator 13.

以上説明したように、本発明によれば反響レベルに対し
重畳（Ｍ号しベルの小さい時や反４！！化号レベルの小
さな時でも、車受通話状態が素早く検出することが可能
で、反響消去層の低下が防止できる０As explained above, according to the present invention, it is possible to quickly detect the car receiving/calling state even when the echo level is superimposed (M and 4! bells are small, and anti-4!! bells are small). 0 that can prevent the decline of the echo cancellation layer

【図面の簡単な説明】[Brief explanation of the drawing]

図は本発明の第１の実施例を示すブロック図である。 The figure is a block diagram showing a first embodiment of the present invention.

Claims (1)

【特許請求の範囲】 （ＩＪ　反響路の入出力信号より反響路の特性を測定し
、得られた反響路特性に基づき近似反響路信号を合成す
ることによシ夫際の反響信号の消去を行なう反響消去装
置において、受話信号レベルを測定する受話信号レベル
測定回路と、受話信号レベルを推定する受話信号レベル
推定部と、前記受話信号レベル測定回路と前記受話信号
レベル推定部の出力レベルとを比較する比較部とを有し
、この比較部の出力により前記反響路の特性を測定する
動作を制御するようにしたことを特徴とする反響消去装
置。 （２）特許請求の範囲第（１１項記載の反響消去装置に
おいて、受話信号レベル推定部が消去残信号レベルを測
定する消去残信号レベル測定ｕ路と、エコーロスとキャ
ンセレーションノ和ヲ求メル減衰量測定回路と、受話信
号レベルの推定値を演算する受話信号レベル推定値演算
回路とｔ有していることを特徴とする反響消去装置。[Claims] (IJ) The characteristics of the echo path are measured from the input and output signals of the echo path, and an approximate echo path signal is synthesized based on the obtained echo path characteristics. In the echo canceling device, a received signal level measurement circuit that measures a received signal level, a received signal level estimator that estimates the received signal level, and an output level of the received signal level measurement circuit and the received signal level estimator are provided. An echo canceling device characterized in that it has a comparison section for comparison, and the operation of measuring the characteristics of the echo path is controlled by the output of the comparison section. (2) Claim No. 11 In the echo cancellation device described above, the received signal level estimator includes a cancellation residual signal level measuring circuit for measuring the cancellation residual signal level, an attenuation measurement circuit that calculates the sum of echo loss and cancellation, and an estimated value of the received signal level. What is claimed is: 1. An echo canceling device comprising: a received signal level estimation value calculation circuit for calculating t;