JPH05183473A - Voice conference device - Google Patents
Voice conference deviceInfo
- Publication number
- JPH05183473A JPH05183473A JP34592291A JP34592291A JPH05183473A JP H05183473 A JPH05183473 A JP H05183473A JP 34592291 A JP34592291 A JP 34592291A JP 34592291 A JP34592291 A JP 34592291A JP H05183473 A JPH05183473 A JP H05183473A
- Authority
- JP
- Japan
- Prior art keywords
- compressor
- input
- signal
- output
- echo
- 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.)
- Pending
Links
Landscapes
- Transmission Systems Not Characterized By The Medium Used For Transmission (AREA)
- Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
- Reduction Or Emphasis Of Bandwidth Of Signals (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は音声会議装置に関し、特
に室内エコーを消去するためのエコーキャンセラを設け
てある音声会議装置に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice conference device, and more particularly to a voice conference device provided with an echo canceller for canceling indoor echo.
【０００２】[0002]
【従来の技術】従来の音声会議装置では送信回路と受信
回路との間にエコーキャンセラを配置して、スピーカか
らマイクロホンへの回り込み信号を消去してハウリング
あるいは鳴音を防止している。2. Description of the Related Art In a conventional audio conference apparatus, an echo canceller is arranged between a transmitting circuit and a receiving circuit to cancel a sneak signal from a speaker to a microphone to prevent howling or ringing.
【０００３】その従来例について図２を参照しつつ以下
説明する。マイクロホン１によって電気信号に変換され
た音声信号は適応型エコーキャンセラ３の実装された送
信パスを通り送受信回路４へ入力され、さらに、送信回
線５へと送信される。また受信回線６から到来した受信
信号は送受信回路４から受信パスを通ってスピーカ８で
音声に変換される。この拡声音はマイクロホン１へ回り
込むこの回り込みによって生じる室内エコーを消去する
ためのエコーキャンセラ３は、受信パスおよび送信パス
の間に接続さている。エコーキャンセラ３では受信信号
を参照して適応フィルタ３１でエコー信号と同波形の擬
似エコー信号を生成し、減算器３２でエコー信号から擬
似エコー信号を減算することで、エコー信号のみを消去
させる。適応アダプティブフィルタのフィルタ係数は送
話者が発信中でなく、受信信号があると判断したとき
に、減算後のエコーが最小になるように修正させてい
る。（適応動作状態）。A conventional example will be described below with reference to FIG. The voice signal converted into an electric signal by the microphone 1 is input to the transmission / reception circuit 4 through the transmission path in which the adaptive echo canceller 3 is mounted, and is further transmitted to the transmission line 5. Further, the received signal coming from the receiving line 6 is converted from the transmitting / receiving circuit 4 into a voice through the receiving path by the speaker 8. This loud sound wraps around to the microphone 1, and an echo canceller 3 for canceling an indoor echo generated by this wraparound is connected between the reception path and the transmission path. In the echo canceller 3, the adaptive filter 31 refers to the received signal to generate a pseudo echo signal having the same waveform as that of the echo signal, and the subtractor 32 subtracts the pseudo echo signal from the echo signal so that only the echo signal is erased. The filter coefficient of the adaptive adaptive filter is modified so that the echo after the subtraction is minimized when it is determined that the talker is not transmitting and there is a received signal. (Adaptive operation state).
【０００４】しかし、このような従来技術では、スピー
カからマイクロホンに回り込むエコー信号が最小レベル
である場合、Ｓ／Ｎ比が劣化し、エコーキャンセラのエ
コー消去量が減少してしまう。However, in such a conventional technique, when the echo signal sneaking from the speaker to the microphone is at the minimum level, the S / N ratio is deteriorated and the echo cancellation amount of the echo canceller is reduced.
【０００５】[0005]
【発明が解決しようとする課題】従来の音声会議装置で
は、スピーカからマイクロホンに回り込むエコー信号が
小レベルである場合、Ｓ／Ｎ彼我劣化し、エコーキャン
セラのエコー消去量が減少してしまう。In the conventional audio conference apparatus, if the echo signal sneaking from the speaker to the microphone is at a low level, the S / N ratio is deteriorated and the echo cancellation amount of the echo canceller is reduced.
【０００６】本発明の目的は、このような従来の問題点
を除去して小レベルの音声信号が入力されてもＳ／Ｎ比
劣化によるエコー消去量の減少を防止した音声会議装置
を提供することにある。An object of the present invention is to eliminate the above-mentioned problems of the related art and provide a voice conference apparatus in which the reduction of the echo cancellation amount due to the deterioration of the S / N ratio is prevented even when a low level voice signal is input. Especially.
【０００７】[0007]
【課題を解決するための手段】上記課題を解決するため
の本発明の第一の解決手段は、音声情報を電気信号に変
換するマイクロホンから入力された送信信号を送信回路
によって送信回線に連なる遠隔配置された相手装置へ送
出すると共に、前記相手装置から受信回線を介して受信
回路によって受信した受信信号を、音声情報に変換する
スピーカに出力し、前記マイクロホンと前記スピーカと
の間で発生するエコーを消去するためのエコーキャンセ
ラを前記マイクロホンの出力端子と前記スピーカの入力
端子との間に接続した音声会議装置において、前記マイ
クロホンの出力端子と前記エコーキャンセラの送信信号
入力端子側との間に介装接続する、入力信号に対する出
力信号特性に所定の性質を持たせた第一の圧縮器と、前
記エコーキャンセラの出力端子と前記送信回路との間に
介装接続する、前記第一の圧縮器の出力信号特性とは逆
特性の入出力特性を有する第一の伸張器と、前記受信回
路と前記エコーキャンセラの受信信号入力端子との間に
介装接続する、前記スピーカからの拡声音声情報の線形
性を保証するための第二の圧縮器と、前記エコーキャン
セラの受信信号入力端子と前記スピーカとの間に介装接
続する、前記第一の圧縮器の非線形分を保証する逆特性
の入出力特性を有する第二の伸張器とを備えたことを特
徴とする。According to a first solution of the present invention for solving the above-mentioned problems, a remote connecting a transmission signal input from a microphone for converting voice information into an electric signal to a transmission line by a transmission circuit. An echo generated between the microphone and the speaker, which outputs the received signal received by the receiving circuit from the partner device via the receiving line via the receiving line to the speaker that converts the information to the speaker, and sends the signal to the partner device. In an audio conferencing apparatus in which an echo canceller for canceling the noise is connected between the output terminal of the microphone and the input terminal of the speaker, an echo canceller is interposed between the output terminal of the microphone and the transmission signal input terminal side of the echo canceller. A first compressor, which is connected and connected to the output signal characteristic with respect to the input signal, and has the echo canceller. A first expander having an input / output characteristic opposite to the output signal characteristic of the first compressor, which is interposed between the output terminal of the receiver and the transmitting circuit, the receiving circuit, and the echo canceller. Between the reception signal input terminal of the echo canceller and the second compressor, which is interposed between the reception signal input terminal of the echo canceller and the second compressor for ensuring the linearity of the loud voice information from the speaker. And a second expander having an input / output characteristic of an inverse characteristic that guarantees a non-linear component of the first compressor.
【０００８】上記課題を解決するための本発明の第二の
解決手段は、上記第一の解決手段記載の音声会議装置に
おける前記第一の圧縮器及び第二の圧縮器の入出力特性
を表わす関数が微分可能であって、しかもその微分係数
が単調減少する関数であり、前記第一の伸張器及び前記
第二の伸張器の入出力特性を表わす関数が、前記第一の
圧縮器の入出力特性を表わす関数の逆関数であることを
特徴とする。A second solving means of the present invention for solving the above problem represents input / output characteristics of the first compressor and the second compressor in the audio conference apparatus described in the first solving means. The function is differentiable, and its differential coefficient is a monotonically decreasing function, and the function representing the input / output characteristics of the first expander and the second expander is the input of the first compressor. It is characterized by being an inverse function of a function representing the output characteristic.
【０００９】[0009]
【実施例】次に本発明について、図面を参照しつつ以下
に説明する。図１は本発明の一実施例のブロック図であ
り、図３は図１における伸張器及び圧縮器の入出力特性
の一例であり、横軸には入力信号振幅値で、縦軸は出力
信号振幅値である。The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 3 is an example of input / output characteristics of the expander and the compressor in FIG. It is an amplitude value.
【００１０】図１において、マイクロホン１は圧縮器２
に接続され、圧縮器２は適応型エコーキャンセラ３の減
算器３２に連なり、この減算器３２の出力端子は伸張器
９に接続されている。伸張器９の出力端子は送受信回路
４を介して送信回線５へと接続されている。これに対し
て、受信回線６は送受信回路４の受信側端子に接続さ
れ、その受信側出力端子は圧縮器１０に接続され、圧縮
器１０の出力端子は適応型エコーキャンセラ３の適応フ
ィルタ３１と伸張器７とに接続され、伸張器７の出力端
子はスピーカ８に、適応フィルタ３１の出力端子は減算
器３２の他方の入力端子に接続されている。In FIG. 1, the microphone 1 is a compressor 2
, The compressor 2 is connected to the subtractor 32 of the adaptive echo canceller 3, and the output terminal of the subtractor 32 is connected to the expander 9. The output terminal of the expander 9 is connected to the transmission line 5 via the transmission / reception circuit 4. On the other hand, the reception line 6 is connected to the reception side terminal of the transmission / reception circuit 4, the reception side output terminal is connected to the compressor 10, and the output terminal of the compressor 10 is the adaptive filter 31 of the adaptive echo canceller 3. The output terminal of the expander 7 is connected to the speaker 8, and the output terminal of the adaptive filter 31 is connected to the other input terminal of the subtractor 32.
【００１１】上記圧縮器２としては、一例として図３に
示すような特性、つまり入出力特性を表わす関数が微分
可能であって、しかもその微分係数が単調減少する関数
である。ここではｙ＝√ｘとした。この関数の特性を有
する圧縮器２は小レベルの入力信号をやや大きくし、大
レベルの入力信号をやや小さくする回路特性をもったも
のである。これにより、小レベル状態でエコーキャンセ
ラに入力されるエコー信号をやや大きな信号に変換して
適応型エコーキャンセラ３に入力し、Ｓ／Ｎ比劣化によ
るエコー消去量の減少を低減させる。As the compressor 2, for example, a function as shown in FIG. 3, that is, a function representing an input / output characteristic is differentiable, and its differential coefficient monotonically decreases. Here, y = √x. The compressor 2 having the characteristic of this function has a circuit characteristic of slightly increasing a small level input signal and slightly reducing a large level input signal. As a result, the echo signal input to the echo canceller in the small level state is converted into a slightly larger signal and input to the adaptive echo canceller 3, and the reduction of the echo cancellation amount due to the S / N ratio deterioration is reduced.
【００１２】さらに、エコー消去後の信号を図３に示す
ような圧縮器２と逆関数関係のある特性（図３ではｙ＝
ｘ2 である）を持つ伸張器９に通すことで、送信信号を
もとの線形信号に戻し、その後送受信回路４によって送
信回線５へと送信する。Further, the signal after echo cancellation has a characteristic having an inverse functional relationship with the compressor 2 as shown in FIG. 3 (y = in FIG. 3).
The transmitted signal is returned to the original linear signal by passing it through the decompressor 9 having x 2 ) and then transmitted to the transmission line 5 by the transmission / reception circuit 4.
【００１３】またエコーキャンセラでは、推定すべきエ
コーパスは線形ではなくてはならないため。このエコー
パスに挿入された圧縮器２の非線形分を、逆特性を備え
る伸張器７を同エコーパスの受信回路側に挿入すること
で、エコーキャンセラからみたエコーパスの線形性を保
たせている。さらに、スピーカから拡声される受信音声
の線形性を損なわせないために、圧縮器１０を受信回路
４と適応型エコーキャンセラ３の受信入力信号端子との
間に介装させている。Also, in the echo canceller, the echo path to be estimated must be linear. The linearity of the echo path seen from the echo canceller is maintained by inserting the non-linear component of the compressor 2 inserted in the echo path into the receiving circuit side of the echo path, which has the inverse characteristic. Further, the compressor 10 is interposed between the reception circuit 4 and the reception input signal terminal of the adaptive echo canceller 3 in order not to impair the linearity of the reception sound amplified by the speaker.
【００１４】[0014]
【発明の効果】以上説明したように本発明は、スピーカ
からマイクロホン１に回り込むエコー信号が小レベルで
ある場合のＳ／Ｎ比の劣化によるエコーキャンセラのエ
コー消去量が減少して十分にエコーを消去できない従来
の欠点を、伸張器によって小レベル入力音声信号程大き
く増幅してＳ／Ｎ比を改善することで、エコー消去量の
減少を低く抑えよるようにした。これにより微小信号が
エコーキャンセラに入力されてもエコー消去量の減少を
軽減できる。またこの伸張器による非線形特性信号にさ
れた音声信号をこの伸張器と逆の増幅特性を有する圧縮
器で線形信号に戻して送信することで、入力された音声
信号の特性を大きく損なうことはない。As described above, according to the present invention, the echo cancellation amount of the echo canceller is reduced due to the deterioration of the S / N ratio when the echo signal sneaking from the speaker to the microphone 1 is at a small level, and the echo is sufficiently echoed. With respect to the conventional drawback that cannot be eliminated, the expander expands the small-level input audio signal as much as possible to improve the S / N ratio so that the reduction in the amount of echo cancellation is suppressed to a low level. As a result, even if a minute signal is input to the echo canceller, it is possible to reduce the decrease in the echo cancellation amount. Further, the characteristic of the input audio signal is not significantly impaired by converting the voice signal converted into the non-linear characteristic signal by the expander into a linear signal by the compressor having an amplification characteristic opposite to that of the expander and transmitting the linear signal. ..
【図１】本発明の一実施例のブロック構成図である。FIG. 1 is a block diagram of an embodiment of the present invention.
【図２】従来の技術の音声会議装置のブロック図であ
る。FIG. 2 is a block diagram of a conventional audio conference apparatus.
【図３】伸張器及び圧縮器野入出力特性図である。FIG. 3 is an input / output characteristic diagram of a stretcher and a compressor field.
１ マイクロホン ２，１０ 圧縮器 ３ 適応型エコーキャンセラ ４ 送受信器 ５ 送信回線 ６ 受信回線 ７，９ 伸張器 ８ スピーカ ３１ 適応フィルタ ３２ 減算器加算器 1 Microphone 2,10 Compressor 3 Adaptive Echo Canceller 4 Transceiver 5 Transmission Line 6 Reception Line 7,9 Expander 8 Speaker 31 Adaptive Filter 32 Subtractor Adder
Claims (2)
ンから入力された送信信号を送信回路によって送信回線
に連なる遠隔配置された相手装置へ送出すると共に、前
記相手装置から受信回線を介して受信回路によって受信
した受信信号を、音声情報に変換するスピーカに出力
し、前記マイクロホンと前記スピーカとの間で発生する
エコーを消去するためのエコーキャンセラを前記マイク
ロホンの出力端子と前記スピーカの入力端子との間に接
続した音声会議装置において、 前記マイクロホンの出力端子と前記エコーキャンセラの
送信信号入力端子側との間に介装接続する、入力信号に
対する出力信号特性に所定の性質を持たせた第一の圧縮
器と、 前記エコーキャンセラの出力端子と前記送信回路との間
に介装接続する、前記第一の圧縮器の出力信号特性とは
逆特性の入出力特性を有する第一の伸張器と、 前記受信回路と前記エコーキャンセラの受信信号入力端
子との間に介装接続する、前記スピーカからの拡声音声
情報の線形性を保証するための第二の圧縮器と、前記エ
コーキャンセラの受信信号入力端子と前記スピーカとの
間に介装接続する、前記第一の圧縮器の非線形分を保証
する逆特性の入出力特性を有する第二の伸張器とを備え
たことを特徴とする音声会議装置。1. A transmission circuit, which transmits a transmission signal input from a microphone for converting voice information into an electric signal, is transmitted by a transmission circuit to a remotely arranged partner device connected to a transmission line, and is also received from the partner device via a reception line. An echo canceller for outputting the received signal received by the speaker to the voice information conversion device and for canceling the echo generated between the microphone and the speaker is provided between the output terminal of the microphone and the input terminal of the speaker. In the audio conferencing device connected between the first and the second output terminals, which are connected between the output terminal of the microphone and the transmission signal input terminal side of the echo canceller, have a predetermined property in the output signal characteristic with respect to the input signal. A compressor, and the first compressor interposed between the output terminal of the echo canceller and the transmission circuit. A first expander having an input / output characteristic opposite to the output signal characteristic, and a linear arrangement of the loud voice information from the speaker, which is interposed between the reception circuit and the reception signal input terminal of the echo canceller. And a second compressor for guaranteeing performance, and an input / output of an inverse characteristic for guaranteeing a non-linear component of the first compressor, which is interposed between the reception signal input terminal of the echo canceller and the speaker. A voice conference device comprising a second expander having characteristics.
力特性を表わす関数が微分可能であって、しかもその微
分係数が単調減少する関数であり、 前記第一の伸張器及び前記第二の伸張器の入出力特性を
表わす関数が、前記第一の圧縮器の入出力特性を表わす
関数の逆関数であることを特徴とする請求項１記載の音
声会議装置。2. A function representing the input / output characteristics of the first compressor and the second compressor is differentiable, and its differential coefficient is a function that monotonically decreases. 2. The audio conference apparatus according to claim 1, wherein the function representing the input / output characteristic of the second expander is an inverse function of the function representing the input / output characteristic of the first compressor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34592291A JPH05183473A (en) | 1991-12-27 | 1991-12-27 | Voice conference device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34592291A JPH05183473A (en) | 1991-12-27 | 1991-12-27 | Voice conference device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05183473A true JPH05183473A (en) | 1993-07-23 |
Family
ID=18379907
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP34592291A Pending JPH05183473A (en) | 1991-12-27 | 1991-12-27 | Voice conference device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05183473A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007318274A (en) * | 2006-05-24 | 2007-12-06 | Yamaha Corp | Sound emission/pickup apparatus |
| JP2010171839A (en) * | 2009-01-26 | 2010-08-05 | Furuno Electric Co Ltd | Wireless communication set |
-
1991
- 1991-12-27 JP JP34592291A patent/JPH05183473A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007318274A (en) * | 2006-05-24 | 2007-12-06 | Yamaha Corp | Sound emission/pickup apparatus |
| JP2010171839A (en) * | 2009-01-26 | 2010-08-05 | Furuno Electric Co Ltd | Wireless communication set |
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