JPS6251836A - Echo erasing device - Google Patents
Echo erasing deviceInfo
- Publication number
- JPS6251836A JPS6251836A JP19243285A JP19243285A JPS6251836A JP S6251836 A JPS6251836 A JP S6251836A JP 19243285 A JP19243285 A JP 19243285A JP 19243285 A JP19243285 A JP 19243285A JP S6251836 A JPS6251836 A JP S6251836A
- Authority
- JP
- Japan
- Prior art keywords
- echo
- adaptive filter
- echo path
- switch
- signal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
Abstract
Description
【発明の詳細な説明】
産業上の利用分野
本発明は、衛星通信等長距離回路やテレコンファレンス
システム等における反響を制御するための反響消去装置
に関するものである。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an echo canceling device for controlling echoes in long-distance circuits such as satellite communications, teleconference systems, and the like.
従来の技術
近年、長距離回線、特に衛星通信の急激な増加やテレコ
ンファレンスシステムの実用化に伴い、明瞭で自然な音
声伝達が望まれている。反響信号は送話者の発生した信
号が受話側での反射等により送話者側に戻ってくる現象
であるが、長距離回線や音響系を含むテレコンファレン
スシステムでは、長い遅延の反響が存在するため通話品
質の劣化を生じている。最近では、この反響を消去する
適応型の反響消去装置が実用化されつつあるが、これら
は遠隔動作型（遠端話者の声で反響路を同定している）
であり近端話者の有無を検出しなければならない。（例
えば双方向同時通話の検出方法、南、川崎、昭和５９年
電子通信学会通信部門全国大会５８９）
以下図面を参照しながら、上述したような従来の反響消
去装置について説明する。2. Description of the Related Art In recent years, with the rapid increase in long-distance lines, especially satellite communications, and the practical use of teleconference systems, clear and natural voice transmission has been desired. Reverberation signals are a phenomenon in which a signal generated by a speaker returns to the speaker due to reflection on the receiver, but in teleconference systems that include long-distance lines and acoustic systems, long-delayed echoes occur. This causes deterioration in call quality. Recently, adaptive echo canceling devices that eliminate this echo are being put into practical use, but these are remote-operated devices (identifying the echo path based on the far-end speaker's voice).
Therefore, the presence or absence of a near-end speaker must be detected. (For example, a method for detecting two-way simultaneous calls, Minami, Kawasaki, 1989 National Conference of the Telecommunications Division of the Institute of Electronics and Communication Engineers, 589) The conventional echo canceling device as described above will be described below with reference to the drawings.
第３図は従来の反響消去装置の構成を示すものである。FIG. 3 shows the configuration of a conventional echo canceling device.
第３図において、１は受信側入力端子、２は受信側出力
端子、３は送信側入力端子、４は送信側出力端子、５は
各端子１〜４の間に設けられたエコーキャンセラで受信
側出力端子から送信側出力端子へ戻ってくるエコーを消
去する。１６はエコーキャンセラ６の送信出力である消
去残′信号のレベルを検出する消去残信号レベル検出部
、１７は受信側信号レベル検出部、１８は消去残信号レ
ベルＬＳｏｕｔ と受信信号レベルＬＲｉｎと前回用
いた閾値Ｋｔから今回用いる閾値Ｋｔを求める閾値更新
部、１９は閾値更新部から送られてきた閾値Ｘｔを記憶
する閾値記憶部、２０は閾値Ｋｔと消去残信号レベルか
ら受信側信号レベルを推定する受信側信号レベル推定部
、２１は推定された受信側信号レベルＬＨｉｎと実際の
受信側信号レベルＬＲ４ｎを比較しエコーキャンセラの
反響路の同定を行うか行わないか制御する比較部である
。In Fig. 3, 1 is the receiving side input terminal, 2 is the receiving side output terminal, 3 is the transmitting side input terminal, 4 is the transmitting side output terminal, and 5 is the echo canceller provided between each terminal 1 to 4. Eliminates the echo that returns from the side output terminal to the transmitting side output terminal. Reference numeral 16 indicates an erased residual signal level detection unit that detects the level of the erased residual signal which is the transmission output of the echo canceller 6, 17 indicates a receiving side signal level detector, and 18 indicates the erased residual signal level LSout, the received signal level LRin, and the previous signal. 19 is a threshold storage unit that stores the threshold value Xt sent from the threshold value Kt, and 20 estimates the receiving side signal level from the threshold value Kt and the erasure residual signal level. The reception side signal level estimator 21 is a comparison unit that compares the estimated reception side signal level LHin with the actual reception side signal level LR4n and controls whether or not to identify the echo path of the echo canceller.
以上のように構成された反響消去装置について、以下そ
の動作について説明する。The operation of the echo canceling device configured as described above will be explained below.
まず、遠端話者の音声信号は受信人力Ｒｉｎ として
受信側入力端子１を経てエコーキャンセラ６に供給され
る。また、しんどうＲｉｎは受信側出力端子２より近端
話者へ受話信号Ｒｏｕｔとして送られる。近端話者信号
のない場合、信号Ｒｏｕｔは反響路を経て、送信側入力
端子３に送信人力Ｓｉｎとして入る。エコーキャンセラ
５では送信側出力信号５ｏｕｔ（消去残信号とも呼ぶ）
が零になるように受信人力Ｒｉｎの系列と送信出力５ｏ
ｕｔがら疑似反響路を作る。このようにして反響信号は
消去されるが、近端話者が存在する場合、反響路の推定
がうまく行う事ができない。従って、近端話者信号の有
る場合を検出し、反響路の推定を停止する必要がある。First, the voice signal of the far end speaker is supplied to the echo canceller 6 via the receiving side input terminal 1 as the receiving human power Rin. Further, the signal Rin is sent from the receiving side output terminal 2 to the near-end speaker as a reception signal Rout. When there is no near-end speaker signal, the signal Rout enters the transmitter input terminal 3 as the transmitter input signal Sin through the echo path. In the echo canceller 5, the transmitting side output signal 5out (also called cancellation residual signal)
The series of receiving human power Rin and the transmitting output 5o so that becomes zero
Create a pseudo echo path from the ut. Although the echo signal is canceled in this way, if a near-end speaker is present, the echo path cannot be estimated successfully. Therefore, it is necessary to detect the presence of a near-end speaker signal and stop estimating the echo path.
そこで、受話側入力信号Ｒｉｎと送信側出力信号である
消去残信号５ｏｕｔの間の関係から近端話者の有無を検
出する。受信側信号レベル検出部７で受信側信号レベル
ＬＲｉｎが検出される。消去残信号レベル検出部１６で
消去残信号レベルＬＳｏｕｔが検出される。閾値更新部
１８では受信側信号レベルＬＪｎと消去残信号レベルＬ
Ｓｏｕｔと閾値記憶部９から前回用いた閾値Ｋｔと比較
部２１から反響路の推定の停止、継続を表す信号ムｄｐ
を受けて今回用いる閾値Ｋｔ’を計算し閾値記憶部
９に送る。次に、受信側信号レベル推定部２０で閾値Ｋ
ｔ’と消去残信号レベルＬＳ□ｕｔから受信側信号レベ
ルの推定値ＬＲｉｎを計算する。Therefore, the presence or absence of a near-end speaker is detected from the relationship between the receiving side input signal Rin and the erasure residual signal 5out which is the transmitting side output signal. A receiving side signal level LRin is detected by the receiving side signal level detection section 7. The erased residual signal level detection section 16 detects the erased residual signal level LSout. The threshold updating unit 18 compares the receiving side signal level LJn and the erased residual signal level L.
Sout, the previously used threshold Kt from the threshold storage section 9, and the signal Mdp from the comparison section 21 indicating the stop or continuation of echo path estimation.
In response to this, the threshold value Kt' to be used this time is calculated and sent to the threshold value storage section 9. Next, the receiving side signal level estimator 20 uses a threshold value K.
An estimated value LRin of the receiving side signal level is calculated from t' and the erased residual signal level LS□ut.
比較部２１では推定した受信側信号レベルと実際／ゞ＼
の受信側信号レベルＬＪｎを比較し、ＬＲｉｎ＞ＬＪｎ
の時、近端話者が存在するとして反響路の推定を停止す
る。The comparator 21 compares the estimated receiving side signal level and the actual receiving side signal level LJn of /ゞ＼, and determines that LRin>LJn
When , it is assumed that a near-end speaker exists and estimation of the echo path is stopped.
閾値の更新方法とし℃は、反響路の推定が進んでいる時
にはエコーキャンセラの収束速度を越えないように閾値
を少しずつ上げて行く。近端話者だけの場合は閾値の更
新は行わない。双方向同時通話、或は反響路の変動の時
には送信側信号レベルで反響路の変動と判定する迄の時
間が著しく変化しないように、打消減衰量に比例した値
だけ閾値を減少させる。前記の判定時間は約３秒とする
。The threshold value is updated by increasing the threshold value little by little as the echo path estimation progresses so as not to exceed the convergence speed of the echo canceller. If there are only near-end speakers, the threshold value is not updated. In the case of simultaneous two-way communication or a change in the echo path, the threshold value is decreased by a value proportional to the amount of cancellation attenuation so that the time required to determine that the change in the echo path is caused by the signal level on the transmitting side does not change significantly. The above judgment time is approximately 3 seconds.
発明が解決しようとする問題点
しかしながら上記のような構成では、テレコンファレン
スシステム等の多人数で会議を行う場合、３秒以上の双
方向同時通話が生じる可能性が多くなるので、判定時間
を長くする必要があり、反響路の変動に対して追随が遅
れるという欠点を有していた。Problems to be Solved by the Invention However, with the above configuration, when holding a conference with a large number of people using a teleconference system, there is a high possibility that two-way simultaneous calls lasting more than 3 seconds will occur, so the determination time will be longer. However, it has the disadvantage that it is slow to follow changes in the echo path.
本発明は上記問題点に鑑み、双方向同時通話と反響路の
変動を高速に判定する事ができる反響消去装置を提供す
るものである。In view of the above-mentioned problems, the present invention provides an echo canceling device that can quickly determine simultaneous two-way communication and fluctuations in the echo path.
問題点を解決するための手段
この目的を達成するために本発明の反響消去装置は、送
信側入力端子に含まれている反響信号を近似合成する第
１及び第２のアダプティブフィルタと、受信入力信号か
ら第１のアダプティブフィルタの出力信号を減算する第
１の減算器と、第１の減算器の出力から第２のアダプテ
ィブフィルタの出力信号を差し引く第２の減算器と、双
方向同時通話時には前記第１の減算器の出力信号を選択
し、その他では前記第２の減算器の出力信号を選択する
第１のスイッチと、前記第２のアダプティブフィルタの
入力信号とじ℃、双方向同時通話時には受信側信号を選
択し、その他では前記第１のアダプティブフィルタに蓄
えられている最終タップの受信信号を選択する第２のス
イッチと、これらのアダプティブフィルタ、スイッチを
制御する双方向同時通話検出部から成る。双方向同時通
話検出部は受信入力信号レベル検出手段と、第１の減算
器の入出力信号の比である第１の反響消去効果を算出す
る第１の反響消去効果算出手段と、第１の減算器の入力
信号と第２の減算器の出力信号の比である第２の反響消
去効果を算出する第２の反響消去効果算出手段と、第１
の反響消去効果算出手段から双方向同時通話或は反響路
の変動を検出し第１のアダプティブフィルタの反響路の
推定を停止する適応停止手段と、第１のアダプティブフ
ィルタの反響消去効果を記憶する効果記憶手段と、効果
記憶手段に蓄えられた第１の反響消去効果と第２の反響
消去効果から双方向同時通話か反響路の変動かを判定し
第１のアダプティブフィルタの反響路特性の推定の再開
か停止、及び第２のアダプティブフィルタのリセ・ノド
、スタート、第１及び第２のスイッチを制御する判定手
段とから構成されている。Means for Solving the Problems In order to achieve this object, the echo canceling device of the present invention includes first and second adaptive filters that approximate synthesize the echo signals included in the transmitting input terminal, and a receiving input terminal. a first subtracter that subtracts the output signal of the first adaptive filter from the signal; and a second subtractor that subtracts the output signal of the second adaptive filter from the output of the first subtracter; A first switch that selects the output signal of the first subtracter, and otherwise selects the output signal of the second subtractor, and the input signal of the second adaptive filter are connected at °C, during simultaneous two-way communication. a second switch that selects a receiving side signal and otherwise selects a final tap received signal stored in the first adaptive filter; and a two-way simultaneous call detection unit that controls these adaptive filters and the switch. Become. The two-way simultaneous call detection unit includes a reception input signal level detection means, a first echo cancellation effect calculation means for calculating a first echo cancellation effect that is a ratio of the input and output signals of the first subtracter, and a first a second echo cancellation effect calculation means for calculating a second echo cancellation effect that is a ratio of the input signal of the subtracter to the output signal of the second subtracter;
adaptive stopping means for detecting simultaneous two-way communication or a change in the echo path from the echo cancellation effect calculating means and stopping estimation of the echo path of the first adaptive filter; and storing the echo cancellation effect of the first adaptive filter. estimating the echo path characteristics of the first adaptive filter by determining whether it is a two-way simultaneous call or a change in the echo path from the effect storage means and the first echo cancellation effect and the second echo cancellation effect stored in the effect storage unit; , restart or stop of the second adaptive filter, restart/start of the second adaptive filter, and determination means for controlling the first and second switches.
作用
この構成によって、近端話者の無い時は第１及び第２の
アダプティブフィルタが反響路を模擬し第１及び第２の
減算器により反響信号を消去する。Operation With this configuration, when there is no near-end speaker, the first and second adaptive filters simulate the echo path and the first and second subtractors cancel the echo signal.
近端話者、或は反響路が変動した時、第１の反響消去効
果算出手段で算出される第１の反響消去効果が低下し、
適応停止手段がこれを検出し直ちに第１のアダプティブ
フィルタの反響路の推定を停止し、判定手段により反響
路の変動か双方向同時通話かを判定する。判定手段では
、第２の反響消去効果算出手段により算出された第２の
反響消去効果と記憶手段に蓄えられτいた第１の反響消
去効果を比較し、第２の反響消去効果と第１の反響消去
効果より大きいと反響路の変動と判定し、第１スイツチ
を第１の減算器から第２の減算器へ切り替え、第２のス
イッチを受信側信号から第１のアダプティブフィルタの
最終タップへ切り替えると同時に、第２のアダプティブ
フィルタをリセットし、第１と第２のアダプティブフィ
ルタの反響路特性の更新を開始させる。前記以外の場合
は、双方向同時通話とみなし第１のアダプティブフィル
タの反響路の推定を停止したままにする。この時、第２
のアダプティブフィルタは判定手段によって一定時間毎
にリセット、スタートされる。このようにして反響路の
変動と双方向同時通話とを第２のアダプティブフィルタ
の収束時間内で判定でき、さらに近端話者のない時には
第１と第２のアダプティブフィルタを合わせたタップ長
のアダプティブフィルタとして長時間の反響信号を消去
することができることとなる。When the near-end speaker or the echo path changes, the first echo cancellation effect calculated by the first echo cancellation effect calculation means decreases,
The adaptive stopping means detects this and immediately stops estimating the echo path of the first adaptive filter, and the determining means determines whether it is a change in the echo path or a simultaneous two-way conversation. The determining means compares the second echo-cancelling effect calculated by the second echo-cancelling effect calculation means with the first echo-cancelling effect stored in the storage means, and determines whether the second echo-cancelling effect is equal to the first echo-cancelling effect. If it is larger than the echo cancellation effect, it is determined that there is a variation in the echo path, the first switch is switched from the first subtracter to the second subtracter, and the second switch is switched from the receiving side signal to the final tap of the first adaptive filter. At the same time as switching, the second adaptive filter is reset and updating of the echo path characteristics of the first and second adaptive filters is started. In cases other than the above, it is assumed that there is a two-way simultaneous conversation, and the estimation of the echo path of the first adaptive filter remains stopped. At this time, the second
The adaptive filter is reset and started at regular intervals by the determining means. In this way, fluctuations in the echo path and simultaneous two-way communication can be determined within the convergence time of the second adaptive filter, and furthermore, when there is no near-end speaker, the combined tap length of the first and second adaptive filters can be determined. This makes it possible to eliminate long-term echo signals as an adaptive filter.
実施例
以下本発明の一実施例について、図面を参照しながら説
明する。EXAMPLE An example of the present invention will be described below with reference to the drawings.
第１図は本発明の一実施例における反響消去装置の構成
を示すものである。FIG. 1 shows the configuration of an echo canceling device in one embodiment of the present invention.
第１図において、１は受信側入力端子、２は受信側出力
端子、３は送信側入力端子、４は送信側出力端子。以上
は第３図の構成と同じものである。In FIG. 1, 1 is a receiving side input terminal, 2 is a receiving side output terminal, 3 is a transmitting side input terminal, and 4 is a transmitting side output terminal. The above configuration is the same as the configuration shown in FIG.
６は受信側出力端子から送信側出力端子へ戻ってくるエ
コーを近似合成する第１のアダプティブフィルタ。６は
送信側入力信号Ｓｉｎから第１のアダプティブフィルタ
で近似合成した信号Ｓｉｎを引く第１の減算器、７は第
１の減算器６の出力Ｄｉｎ を近似合成する第２のア
ダプティブフィルタ、８は第１の減算器６の出力Ｄｉｎ
から第２のアダプティブフィルタ７の出力Ｄｉｎを引く
第２の減算器、１ｏは送信側出力信号５ｏｕｔとして第
１の減算器６の出力信号Ｓｉｎか第２の減算器８の出力
信号Ｄｏｕｔ受信側入力信号Ｒ１ｎと第２の減算器のＤ
ｏｕｔかを選択する第１のスイッチ、１１は第２のアダ
プティブフィルタ７の受信入力として受信側入力信号Ｒ
ｉｎか第１のアダプティブフィルタ６の最終タップの信
号かを選択する第２のスイッチ、９は受信側入力信号Ｒ
ｉｎと送信側出力信号Ｓｉｎと送信側出力信号５ｏｕｔ
と第２の減算器７の出力信号Ｄｏｕｔから近端話者の有
無を検出し、第１及び第２のアダプティブフィルタ６゜
７および第１．第２のスイ・ノテ１０，１１を制御する
双方向同時通話検出部である。6 is a first adaptive filter that approximately synthesizes echoes returning from the receiving output terminal to the transmitting output terminal; 6 is a first subtracter that subtracts the signal Sin approximately synthesized by the first adaptive filter from the transmitting side input signal Sin; 7 is a second adaptive filter that approximately synthesizes the output Din of the first subtracter 6; 8 is a Output Din of the first subtractor 6
A second subtractor 1o subtracts the output Din of the second adaptive filter 7 from the output signal 5out on the transmitting side, and the output signal Sin of the first subtractor 6 or the output signal Dout of the second subtractor 8 on the receiving side. Signal R1n and second subtractor D
A first switch 11 selects whether to output or output the receiving side input signal R as the receiving input of the second adaptive filter 7.
A second switch 9 selects between the input signal R and the signal from the final tap of the first adaptive filter 6;
in, transmitting side output signal Sin, and transmitting side output signal 5out
The presence or absence of a near-end speaker is detected from the output signal Dout of the second subtractor 7 and the first and second adaptive filters 6.7 and the first . This is a two-way simultaneous call detection unit that controls the second Sui Notes 10 and 11.
第２図は双方向同時通話検出部９の詳細な構成を示すブ
ロック図である。第２図において、９１は第１の減算器
６の出力信号Ｄｉｎと送信側入力信号Ｓｉｎとの比ムｃ
ｎｃ１（以下第１の反響消去効果と呼ぶ）を算出する第
１の反響消去効果算出手段、９２は第２の減算器８の出
力信号ＤＯｕｔと送信側入力信号Ｓｉｎとの比ムＣｎＣ
２（以下第２の反響消去効果と呼ぶ）を算出するから第
２の反響消去効果算出手段、９３は受信側入力信号Ｒｉ
ｎの信号レベルを検出する受信信号レベル検出手段、９
４は第１の反響消去装置人ｃｎｃ１から双方向同時通話
、或は反響路の変動を検出する検出手段、９６は第１の
アダプティブフィルタが反響路の推定を行っている時の
第１の反響消去効果ムｃｎｃ１を反響消去効果ＡＣｎＣ
として記憶する効果記憶手段、９６は効果記憶手段９５
に記憶された反響消去効果ムｃｎｃと第２の反響消去効
果ＡＣｎＣ２を比較して双方向同時通話と反響路の変動
を判定し第１および第２のアダプティブフィルタの反響
路の推定、第１および第２のスイッチを制御する判定手
段である。第１と第２のアダプティブフィルタのタップ
長は同じである。FIG. 2 is a block diagram showing the detailed configuration of the two-way simultaneous call detection section 9. As shown in FIG. In FIG. 2, 91 is the ratio c of the output signal Din of the first subtractor 6 and the input signal Sin on the transmitting side.
nc1 (hereinafter referred to as the first echo cancellation effect); 92 is the ratio CnC of the output signal DOut of the second subtracter 8 and the transmission side input signal Sin;
2 (hereinafter referred to as the second echo cancellation effect), the second echo cancellation effect calculating means 93 calculates the receiving side input signal Ri.
received signal level detection means for detecting the signal level of n;
4 is a detection means for detecting two-way simultaneous communication from the first echo canceller CNC1 or a change in the echo path; 96 is a first echo when the first adaptive filter is estimating the echo path; Elimination effect Mcnc1 Echo cancellation effect ACnC
96 is an effect storage means 95 for storing
The echo cancellation effect ACnC2 stored in the echo cancellation effect ACnC2 is compared with the second echo cancellation effect ACnC2 to determine two-way simultaneous communication and fluctuations in the echo path, and the echo paths of the first and second adaptive filters are estimated. This is determination means for controlling the second switch. The tap lengths of the first and second adaptive filters are the same.
以上のように構成された反響消去装置について、以下そ
の動作を説明する。The operation of the echo canceling device configured as described above will be explained below.
まず、遠端話者の音声信号は受信人力Ｒｉｎとして受信
側入力端子１を経て第１のアダプティブフィルタ５に供
給される。また、信号Ｒｉｎは受信側出力端子２より近
端話者へ受話信号Ｒｏｕｔとして送られる。近端話者信
号のない場合、信号Ｒｏｕｔは反響路を経て、送信側入
力端子３に送信人力Ｓｉｎとして入る。近端話者のない
時は第１のスイッチは第２の減算器に接続され、第２の
スイ・ノテは第１のアダプティブフィルタの最終タップ
へ接続されτいる。このため第１および第２のアダプテ
ィブフィルタ５．６は一つアダプティブフィルタと成り
受信側出力端子２から送信側入力端子３までの反響路を
推定するように動作する。First, the voice signal of the far end speaker is supplied to the first adaptive filter 5 via the receiving side input terminal 1 as the receiving human power Rin. Further, the signal Rin is sent from the receiving side output terminal 2 to the near-end speaker as a reception signal Rout. When there is no near-end speaker signal, the signal Rout enters the transmitter input terminal 3 as the transmitter input signal Sin through the echo path. When there is no near-end talker, the first switch is connected to the second subtractor, and the second switch is connected to the last tap of the first adaptive filter. Therefore, the first and second adaptive filters 5.6 function as one adaptive filter and operate to estimate the echo path from the receiving side output terminal 2 to the transmitting side input terminal 3.
第１および第２のアダプティブフィルタ６．７の具体的
な動作を説明する。第１のアダプティブフィルタ５では
第１の減算器６の出力信号Ｄｉｎが零になるように受信
人力Ｒｉｎの系列と出力信号Ｄｉｎ から疑似反響路
を作る。第２のアダプティブフィルタ７も第１のアダプ
ティブフィルタ５と同様に第２の減算器８の出力信号Ｄ
ｏｕｔが零になるように第１のアダプティブフィルタ６
の最終り・ツブから受は取った受信人力Ｒｉｎの系列と
出力信号Ｄｏｕｔから疑似反響路を作る。このようにし
て第１および第２のアダプティブフィルタ５．７を合わ
せたタップ長の疑似反響路が作られ反響信号は消去され
るが、近端話者が存在する場合、反響路の推定がうまく
行う事ができない。従って、近端話者信号の有る場合を
検出し、反響路の推定を停止する必要がある。双方向同
時通話検出部７は以下のようにして近端話者の有無を検
出し第１および第２のアダプティブフィルタ５．７、第
１および第２のスイッチ６．８を制御する。近端話者、
或は反響路が変動した時、第１の反響消去効果算出手段
９１で算出される第１の反響消去効果ＡＣｎＯ１が低下
し、適応停止手段９３がこれを検出し、停止信号Ｓｔｐ
が出される。判定手段９６では停止信号Ｓｔｐを受ける
と第１のアダプティブフィルタの反響路の推定を停止す
るように適応制御信号ムｄｐを１、第２のアダプティブ
フィルタ７を一端リセットしくＲ／Ｓを′１′ ）すぐ
に適応を開始させる（Ｒ／Ｓを′０′）ようにリセット
信号Ｒ／Ｓを出す。更に第１のスイッチを第１の減算器
の出力、第２のスイッチを受信側入力信号Ｒｉｎを選択
するように制御する。これにより第１のアダプティブフ
ィルタ６は模擬した反響路を保持し、第２のアダプティ
ブフィルタ７は受信側入力端子２から第１の減算器６ま
での反響路の推定を始める。次に判定手段９６では第２
の反響消去効果算出手段９２により算出された第２の反
響消去効果ｋｏｎ０２と効果記憶手段９６に蓄見られて
いた第１の反響消去効果Ａｃｎａを比較し・反響消去効
果ｋｏｎｏとＡＯｎＯ２が等しい時は、反響路の変動と
判定し第１のアダプティブフィルタ５の反響路の推定を
開始させるように適応制御信号Ａｄｐを′０′、第２の
アダプティブフィルタ７をリセットしくリセ・ノドスタ
ート信号Ｒ／Ｓを１１１）、すぐに適応をスタートさせ
る（リセットスタート信号Ｒ／Ｓを′○′ ）と同時に
、第１のスイッチ１ｏを第２の減算器８の出力、第２の
スイッチ１１を第１のアダプティブフィルタの最終タッ
プを選択するように制御する。これにより最初の近端話
者のない状態に戻る。第２の反響消去効果ｋｏｎ０２が
効果記憶手段９５に蓄えられていた第１の反響消去効果
ＡＣｎＯより劣化している時は、近端話者が存在したと
みなし第１のアダプティブフィルタ５の反響路の推定を
停止したままにするように適応制御信号Ａｄｐを′１′
のままにしておく。この時、第２のエコーキャンセラ６
は判定手段９６から一定時間毎に出されるリセット、ス
タート信号Ｒ／Ｓによってリセット、スタートされる。The specific operations of the first and second adaptive filters 6.7 will be explained. The first adaptive filter 5 creates a pseudo echo path from the series of receiving human power Rin and the output signal Din so that the output signal Din of the first subtractor 6 becomes zero. Similarly to the first adaptive filter 5, the second adaptive filter 7 also receives the output signal D of the second subtracter 8.
The first adaptive filter 6 so that out becomes zero.
A pseudo echo path is created from the sequence of the receiving power Rin and the output signal Dout taken from the last signal. In this way, a pseudo echo path with the combined tap length of the first and second adaptive filters 5.7 is created and the echo signal is canceled, but if there is a near-end speaker, the echo path cannot be estimated successfully. I can't do it. Therefore, it is necessary to detect the presence of a near-end speaker signal and stop estimating the echo path. The two-way simultaneous call detection unit 7 detects the presence or absence of a near-end speaker and controls the first and second adaptive filters 5.7 and the first and second switches 6.8 in the following manner. near-end speaker,
Alternatively, when the echo path changes, the first echo cancellation effect ACnO1 calculated by the first echo cancellation effect calculation means 91 decreases, and the adaptive stop means 93 detects this and outputs the stop signal Stp.
is served. Upon receiving the stop signal Stp, the determining means 96 sets the adaptive control signal Mdp to 1 so as to stop estimating the echo path of the first adaptive filter, and sets R/S to '1' to temporarily reset the second adaptive filter 7. ) A reset signal R/S is issued to immediately start adaptation (R/S is set to '0'). Further, the first switch is controlled to select the output of the first subtracter, and the second switch is controlled to select the receiving side input signal Rin. As a result, the first adaptive filter 6 holds the simulated echo path, and the second adaptive filter 7 starts estimating the echo path from the receiving side input terminal 2 to the first subtractor 6. Next, in the determining means 96, the second
The second echo canceling effect kon02 calculated by the echo canceling effect calculating means 92 is compared with the first echo canceling effect Acna stored in the effect storage means 96. When the echo canceling effect kono and AOnO2 are equal, , the adaptive control signal Adp is set to '0' so that it is determined that there is a change in the echo path, and estimation of the echo path of the first adaptive filter 5 is started, and the reset node start signal R/S is set to reset the second adaptive filter 7. 111), immediately start adaptation (set the reset start signal R/S to '○'), and at the same time set the first switch 1o to the output of the second subtracter 8 and the second switch 11 to the first adaptive switch. Controls the selection of the final tap of the filter. This returns to the initial near-end speakerless state. When the second echo cancellation effect kon02 is worse than the first echo cancellation effect ACnO stored in the effect storage means 95, it is assumed that a near-end speaker exists, and the echo path of the first adaptive filter 5 The adaptive control signal Adp is set to '1' to keep the estimation of
Leave it as is. At this time, the second echo canceller 6
is reset and started by a reset and start signal R/S issued from the determination means 96 at regular intervals.
但し、受信信号レベル検出手段９３において受信側入力
信号ＲｉｎのレベルＬＨ４ｎが予め決められた閾値より
小さい時には雑音とみなしτ第１および第２のアダプテ
ィブフィルタの反響路の推定を停止する。このようにし
て反響路の変動と双方向同時通話とを第２のアダプティ
ブフィルタ７の収束時間内で判定できることとなる。However, when the level LH4n of the receiving side input signal Rin is smaller than a predetermined threshold in the received signal level detecting means 93, it is regarded as noise and the estimation of the echo paths of the τ first and second adaptive filters is stopped. In this way, fluctuations in the echo path and simultaneous bidirectional communication can be determined within the convergence time of the second adaptive filter 7.
以上のように本実施例によれば、近端話者の無い時は第
１及び第２のアダプティブフィルタが反響路を模擬し第
１及び第２の減算器により反響信号を消去する。近端話
者、或は反響路が変動した時、第１の反響消去効果算出
手段で算出される第１の反響消去効果が低下し、適応停
止手段がこれを検出し直ちに第１のアダプティブフィル
タの反響路の推定を停止し、判定手段により反響路の変
動か双方向同時通話かを判定する。判定手段では、第２
の反響消去効果算出手段により算出された第２の反響消
去効果と記憶手段に蓄えられていた第１の反響消去効果
を比較し、第２の反響消去効果と第１の反響消去効果よ
り大きいと反響路の変動と判定し、第１スイ・ソテを第
１の減算器から第２の減算器へ切り替え、第２のスイ、
ソチを受信側信号から第１のアダプティブフィルタの最
終タップへ切り替えると同時に、第２のアダプティブフ
ィルタをリセットし、第１と第２のアダプティブフィル
タの反響路特性の更新を開始させる。前記以外の場合は
、双方向同時通話とみなし第１のアダプティブフィルタ
の反響路の推定を停止したままにする。この時、第２の
アダプティブフィルタは判定手段によって一定時間毎に
リセット、スタートされる。近端話者か反響路の変動か
の判定時および近端話者が存在する時には第１のアダプ
ティブフィルタが反響信号を消去する。判定時間は短く
、近端話者が存在する時は反響信号は聴感上気にならな
い。このようにして反響路の変動と双方向同時通話とを
第２のアダプティブフィルタの収束時間内で判定でき、
さらに近端話者のない時には第１と第２のアダプティブ
フィルタを合わせたり・ツブ長のアダプティブフィルタ
として長時間の反響信号を消去することができることと
なる。As described above, according to this embodiment, when there is no near-end speaker, the first and second adaptive filters simulate the echo path, and the first and second subtracters cancel the echo signal. When the near-end speaker or the echo path changes, the first echo cancellation effect calculated by the first echo cancellation effect calculation means decreases, and the adaptive stop means detects this and immediately stops the first adaptive filter. The estimation of the echo path is stopped, and the determining means determines whether the echo path is changing or whether there is a simultaneous two-way conversation. In the determination means, the second
The second echo-cancelling effect calculated by the echo-cancelling effect calculating means is compared with the first echo-cancelling effect stored in the storage means, and if the second echo-cancelling effect is greater than the first echo-cancelling effect. It is determined that there is a change in the echo path, and the first switch is switched from the first subtractor to the second subtractor, and the second switch is changed.
Simultaneously with switching the Sochi from the receiving signal to the final tap of the first adaptive filter, the second adaptive filter is reset and updating of the echo path characteristics of the first and second adaptive filters is initiated. In cases other than the above, it is assumed that there is a two-way simultaneous conversation, and the estimation of the echo path of the first adaptive filter remains stopped. At this time, the second adaptive filter is reset and started at regular intervals by the determining means. When determining whether it is a near-end talker or a variation in the echo path, and when a near-end talker is present, a first adaptive filter cancels the echo signal. The determination time is short, and when a near-end speaker is present, the echo signal is not audible. In this way, fluctuations in the echo path and simultaneous two-way communication can be determined within the convergence time of the second adaptive filter,
Furthermore, when there is no near-end speaker, the first and second adaptive filters can be combined or used as a long-length adaptive filter to eliminate long-term echo signals.
なお、本実施例では第２のアダプティブフィルタを第１
のアダプティブフィルタと同じ遅延量を有するアダプテ
ィブフィルタとしたが、第１のアダプティブフィルタの
遅延量より小さい遅延量のアダプティブフィルタであっ
ても良い。この場合は判定手段において、第１の反響消
去効果と第２の反響消去効果を比較する際に、第２のア
ダプティブフィルタの遅延量の少ない分に相当する反響
消去効果の劣化分を第２の反響消去効果に加えれば良い
。第２のアダプティブフィルタの遅延量を小さくするこ
とにより、装置の規模を縮小する事ができたり、第２の
アダプティブフィルタの収束速度が速くなり双方向同時
通話と反響路の変動との判定がより高速になる。Note that in this embodiment, the second adaptive filter is
Although the adaptive filter has the same delay amount as the first adaptive filter, the adaptive filter may have a delay amount smaller than the delay amount of the first adaptive filter. In this case, in the determination means, when comparing the first echo cancellation effect and the second echo cancellation effect, the deterioration of the echo cancellation effect corresponding to the smaller delay amount of the second adaptive filter is Just add it to the echo cancellation effect. By reducing the delay amount of the second adaptive filter, the scale of the device can be reduced, and the convergence speed of the second adaptive filter becomes faster, making it easier to distinguish between simultaneous two-way communication and fluctuations in the echo path. Becomes faster.
なお、第１の反響消去効果を第１の減算器の出力信号と
送信側入力信号の比としたが、送信側出力信号と送信側
入力信号の比としても良い。この場合は判定手段におい
て、第１の反響消去効果と第２の反響消去効果を比較す
る際に、第１と第２のアダプティブフィルタの遅延量に
対し１第２のアダプティブフィルタの遅延量の少ない分
に相当する反響消去効果の劣化分を第２の反響消去効果
に加えれば良い。Although the first echo cancellation effect is defined as the ratio between the output signal of the first subtracter and the input signal on the transmitting side, it may also be the ratio between the output signal on the transmitting side and the input signal on the transmitting side. In this case, in the determination means, when comparing the first echo cancellation effect and the second echo cancellation effect, it is determined that the delay amount of the second adaptive filter is smaller than the delay amount of the first and second adaptive filters. It is sufficient to add the deterioration of the echo canceling effect corresponding to the second echo canceling effect to the second echo canceling effect.
発明の効果
以上のように本発明は、近端話者の無い時は第１及び第
２のアダプティブフィルタが反響路を模擬し第１及び第
２の減算器により反響信号を消去する。近端話者、或は
反響路が変動した時、第１の反響消去効果算出手段で算
出される第１の反響消去効果が低下し、適応停止手段が
これを検出し直ちに第１のアダプティブフィルタの反響
路の推定を停止し、判定手段により反響路の変動か双方
向同時通話かを判定する。判定手段では、第２の反響消
去効果算出手段により算出された第２の反響消去効果と
記憶手段に蓄えられていた第１の反響消去効果を比較し
、第２の反響消去効果と第１の反響消去効果より大きい
と反響路の変動と判定し、第１スイツチを第１の減算器
から第２の減算器へ切り替え、第２のスイッチを受信側
信号から第１のアダプティブフィルタの最終タップへ切
り替えると同時に、第２のアダプティブフィルタをリセ
ットし、第１と第２のアダプティブフィルタの反響路特
性の更新を開始させる。前記以外の場合は、双方向同時
通話とみなし第１のアダプティブフィルタの反響路の推
定を停止したままにする。Effects of the Invention As described above, in the present invention, when there is no near-end speaker, the first and second adaptive filters simulate the echo path, and the first and second subtractors cancel the echo signal. When the near-end speaker or the echo path changes, the first echo cancellation effect calculated by the first echo cancellation effect calculation means decreases, and the adaptive stop means detects this and immediately stops the first adaptive filter. The estimation of the echo path is stopped, and the determining means determines whether the echo path is changing or whether there is a simultaneous two-way conversation. The determining means compares the second echo-cancelling effect calculated by the second echo-cancelling effect calculation means with the first echo-cancelling effect stored in the storage means, and compares the second echo-cancelling effect with the first echo-cancelling effect. If it is larger than the echo cancellation effect, it is determined that there is a variation in the echo path, the first switch is switched from the first subtracter to the second subtracter, and the second switch is switched from the receiving side signal to the final tap of the first adaptive filter. At the same time as switching, the second adaptive filter is reset and updating of the echo path characteristics of the first and second adaptive filters is started. In cases other than the above, it is assumed that there is a two-way simultaneous conversation, and the estimation of the echo path of the first adaptive filter remains stopped.
この時、第２のアダプティブフィルタは判定手段によっ
て一定時間毎にリセット、スタートされる。At this time, the second adaptive filter is reset and started at regular intervals by the determining means.
近端話者か反響路の変動かの判定時および近端話者が存
在する時には第１のアダプティブフィルタが反響信号を
消去する。判定時間は短く、近端話者が存在する時は反
響信号は聴感上気にならない。When determining whether it is a near-end talker or a variation in the echo path, and when a near-end talker is present, a first adaptive filter cancels the echo signal. The determination time is short, and when a near-end speaker is present, the echo signal is not audible.
このようにして反響路の変動と双方向同時通話とを第２
のアダプティブフィルタの収束時間内で判定でき、さら
に近端話者のない時には第１と第２のアダプティブフィ
ルタを合わせた夕・ツブ長のアダプティブフィルタとし
て長時間の反響信号を消去することができ、アダプティ
ブフィルタが常に良好に反響路を模擬し、多人数でのテ
レコンフルンスシステムにおいても優れた反響消去をお
こなうことができ、その実用的効果は犬なるものである
。In this way, fluctuations in the echo path and simultaneous two-way communication can be
It can be determined within the convergence time of the adaptive filter, and furthermore, when there is no near-end speaker, the long-term echo signal can be canceled as a long-length adaptive filter that combines the first and second adaptive filters. The adaptive filter always simulates the echo path well and can perform excellent echo cancellation even in a multi-person teleconfluence system, and its practical effects are outstanding.
第１図は本発明の一実施例における反響消去装置の構成
を示すブロック図、第２図は本発明の一実施例における
反響消去装置の双方向同時通話検出部のブロック図、第
３図は従来の反響消去装置のブロック図である。
６・・・・・・第１のアダプティブフィルタ、６・・・
・・・第１の減算器、７・・・・・・第２のアダプティ
ブフィルタ、８・・・・・・第２の減算器、９・・・・
・・双方向同時通話検出部、１ｏ・・・・・・第１のス
イツチ、１１・・・・・・第２のスイッチ、９１・・・
・・・第１の反響消去効果算出手段、９２・・・・・・
第２の反響消去効果算出手段、９３・・・・・・受信信
号レベル検出手段、９４・・・・・・適応停止手段、９
５・・・・・・効果記憶手段、９６・・・・・・判定手
段。
代理人の氏名 弁理士 中 尾 敏 男 ほか１名第１
図
第２図
第３図FIG. 1 is a block diagram showing the configuration of an echo canceling device in an embodiment of the present invention, FIG. 2 is a block diagram of a two-way simultaneous call detection section of the echo canceling device in an embodiment of the present invention, and FIG. 3 is a block diagram showing the configuration of an echo canceling device in an embodiment of the present invention. FIG. 1 is a block diagram of a conventional echo cancellation device. 6...First adaptive filter, 6...
...First subtractor, 7...Second adaptive filter, 8...Second subtractor, 9...
...Two-way simultaneous call detection unit, 1o...First switch, 11...Second switch, 91...
...First echo cancellation effect calculation means, 92...
Second echo cancellation effect calculation means, 93... Received signal level detection means, 94... Adaptive stop means, 9
5... Effect storage means, 96... Judgment means. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3
Claims (3)
に含まれる反響信号を近似合成する第１及び第２アダプ
ティブフィルタと、送信側入力信号から前記第１のアダ
プティブフィルタの出力信号である第１の疑似反響信号
を減算する第１の減算器と、前記第１の減算器の出力信
号から前記第２のアダプティブフィルタの出力信号であ
る第２の疑似反響信号を減算する第２の減算器と、前記
第１及び第２の減算器の出力信号と送受信側の入出力信
号から双方向同時通話を検出する双方向同時通話検出手
段と、送信側出力信号として、近端話者のある時または
反響路の変動の初期には前記第１の減算器の出力信号を
選択し、その他では前記第２の減算器の出力信号を選択
する第１のスイッチと、前記第２のアダプティブフィル
タの受信入力信号として、近端話者のある時または反響
路の変動の初期には受信側信号を選択し、その他では前
記第１のアダプティブフィルタに蓄えられている最終タ
ップの受信信号を選択する第２のスイッチとを備えたこ
とを特徴とする反響消去装置。(1) First and second adaptive filters that adaptively simulate the characteristics of the echo path and approximately synthesize the echo signals included in the transmission side input signal, and the output signal of the first adaptive filter from the transmission side input signal. a first subtracter that subtracts a first pseudo-echo signal, which is the output signal of the second adaptive filter; a two-way simultaneous call detection means for detecting a two-way simultaneous call from the output signals of the first and second subtracters and the input/output signals of the transmitting and receiving sides; a first switch that selects the output signal of the first subtractor at a certain time or at the beginning of a variation of the echo path and selects the output signal of the second subtractor at other times; As the received input signal of the filter, the receiving side signal is selected when there is a near-end talker or at the beginning of the fluctuation of the echo path, and at other times, the received signal of the last tap stored in the first adaptive filter is selected. An echo canceling device characterized in that it is equipped with a second switch.
検出する受信信号レベル検出手段と、第１の減算器の出
力信号レベルと送信側入力信号レベルの比である第１の
反響消去効果を算出する第１の反響消去効果算出手段と
、受信側入力信号レベルと第１の反響消去効果から近端
話者或は反響路の変動を検出し、第１のアダプティブフ
ィルタの反響路特性の更新を停止すると同時に、第１の
スイッチを第２の減算器から前記第１の減算器へ切り替
え、第２のスイッチを前記第１のアダプティブフィルタ
の最終タップから受信側信号へ切り替えるように制御す
る適応停止手段と、前記第２の減算器の出力信号レベル
と前記第１の減算器の入力信号レベルの比である第２の
反響消去効果を計算する第２の反響消去効果算出手段と
、前記第１のアダプティブフィルタの係数更新時の第１
の反響消去効果を記憶しておく効果記憶手段と、前記適
応停止手段が近端話者或は反響路の変動があることを検
出した時、前記効果記憶手段にある第１の反響消去効果
と第２の反響消去効果から近端話者か反響路の変動かを
判定し、反響路の変動の時は、第１スイッチを前記第１
の減算器から前記第２の減算器へ切り替え、前記第２の
スイッチを受信側信号から前記第１のアダプティブフィ
ルタの最終タップへ切り替えると同時に、第２のアダプ
ティブフィルタをリセットし、前記第１と前記第２のア
ダプティブフィルタの反響路特性の更新を開始させ、近
端話者の時は、前記第１のアダプティブフィルタの反響
路特性の更新を停止したままにしておく判定手段とから
構成されることを特徴とする特許請求の範囲第１項記載
の反響消去装置。(2) A receiving signal level detection means in which the two-way simultaneous call detection unit detects the input signal level on the receiving side, and a first echo cancellation effect that is the ratio of the output signal level of the first subtracter and the input signal level on the transmitting side. a first echo cancellation effect calculation means for calculating the echo cancellation effect, and a first echo cancellation effect calculation means for detecting a change in the near-end speaker or the echo path from the receiving side input signal level and the first echo cancellation effect, and detecting a change in the echo path characteristic of the first adaptive filter. At the same time as stopping the update, controlling a first switch to switch from a second subtracter to the first subtractor, and a second switch to switch from the final tap of the first adaptive filter to the receiving signal. adaptive stopping means; second echo cancellation effect calculation means for calculating a second echo cancellation effect that is a ratio of the output signal level of the second subtractor and the input signal level of the first subtractor; The first when updating the coefficients of the first adaptive filter
effect storage means for storing a first echo cancellation effect stored in the effect storage means when the adaptive stop means detects that there is a change in the near-end speaker or the echo path; It is determined from the second echo canceling effect whether it is a near-end speaker or a change in the echo path, and when the echo path is changing, the first switch is switched to the first switch.
switch from the subtracter of the first adaptive filter to the second subtractor, switch the second switch from the receiving signal to the last tap of the first adaptive filter, and at the same time reset the second adaptive filter, determining means for starting updating of the echo path characteristics of the second adaptive filter, and stopping updating of the echo path characteristics of the first adaptive filter when the user is a near-end speaker; An echo canceling device according to claim 1, characterized in that:
の更新を停止した後、一定の時間間隔で第２のアダプテ
ィブフィルタを一旦リセットし、再スタートする事を特
徴とする特許請求の範囲第２項記載の反響消去装置。(3) After the determining means stops updating the echo path characteristics of the first echo canceller, the second adaptive filter is reset and restarted at regular time intervals. The echo canceling device described in Section 2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19243285A JPS6251836A (en) | 1985-08-30 | 1985-08-30 | Echo erasing device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19243285A JPS6251836A (en) | 1985-08-30 | 1985-08-30 | Echo erasing device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6251836A true JPS6251836A (en) | 1987-03-06 |
| JPH0413892B2 JPH0413892B2 (en) | 1992-03-11 |
Family
ID=16291209
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP19243285A Granted JPS6251836A (en) | 1985-08-30 | 1985-08-30 | Echo erasing device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6251836A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03154533A (en) * | 1989-11-13 | 1991-07-02 | Nec Corp | Digital multiplexer |
-
1985
- 1985-08-30 JP JP19243285A patent/JPS6251836A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03154533A (en) * | 1989-11-13 | 1991-07-02 | Nec Corp | Digital multiplexer |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0413892B2 (en) | 1992-03-11 |
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