JPH0244408B2

JPH0244408B2 - EKOOKYANSERAGATASOHOKOZOFUKUKI

Info

Publication number: JPH0244408B2
Application number: JP18418784A
Authority: JP
Inventors: Tadasuke Maruyama; Hitoshi Fuda; Hiroshi Yasukawa; Masaharu Shimada
Original assignee: Nippon Telegraph and Telephone Corp; Nippon Electric Co Ltd
Current assignee: NEC Corp; Nippon Telegraph and Telephone Corp
Priority date: 1984-09-03
Filing date: 1984-09-03
Publication date: 1990-10-03
Anticipated expiration: 2004-09-03
Also published as: JPS6162217A

Description

【発明の詳細な説明】〔技術分野〕本発明はエコーキヤンセラを用いた双方向増幅
器の利得制御に関する。DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to gain control of a bidirectional amplifier using an echo canceller.

[Prior art]

電話回線の途中に挿入される双方向増幅器（例
えば自動着信転送を行う場合に転送回線の伝送損
失を補償するための双方向中継器）として、被増
幅信号である音声信号の電力の値を検出し、その
値により利得を制御するAGC方式を適用した増
幅器が使用されている。このようなAGC方式は、
増幅器が挿入接続される回線が変わると、回線損
失がかなり変化し、特に回線損失が大きい場合に
は、通話をできるだけ早く開始するために、回線
接続開始時から所要の利得に達するまでの時間が
短いことが要求される。 As a bidirectional amplifier inserted in the middle of a telephone line (for example, a bidirectional repeater to compensate for transmission loss in the transfer line when performing automatic call transfer), it detects the power value of the voice signal that is the signal to be amplified. However, an amplifier is used that uses the AGC method to control the gain based on this value. This kind of AGC method is
When the line into which the amplifier is inserted and connected changes, the line loss changes considerably, and in order to start the call as soon as possible, especially when the line loss is large, the time from the start of the line connection until the required gain is reached is increased. Must be short.

一方、双方向増幅器では構成上、閉ループがで
きるため、閉ループの一巡利得を鳴音余裕（−
7dB）以下にする必要がある。このため、従来の
双方向増幅器では、一方向の増幅器に利得を与え
た場合には、他方向には〔挿入利得〕＋7dBの損
失を挿入することにより、鳴音状態にならないよ
う調整している。しかし、このような方式では、
一方に信号がある場合、上述した（挿入損失＋
7dB）という損失のため他方からの信号は伝わら
ず、いわゆる話頭、語尾切断が生じる。このよう
な問題を解決するため、従来エコーキヤンセラを
用いて、２線４線変換点の反響信号を打ち消し
て、閉ループの一巡利得を小さくする双方向増幅
器が提案されている。しかしながら、エコーキヤ
ンセラを使用した双方向増幅器では、話頭，語尾
切断は生じないが、エコーキヤンセラの性格上、
回線が変わると一定の反響打ち消し量を得るため
にエコーキヤンセラの調整時間を必要とし、この
エコーキヤンセラ調整時間中はほとんど通話がで
きなくなるという欠点がある。 On the other hand, since a bidirectional amplifier has a closed loop due to its configuration, the closed loop gain is calculated by the sound margin (-
7dB) or less. For this reason, in conventional bidirectional amplifiers, when gain is given to the amplifier in one direction, a loss of [insertion gain] +7 dB is inserted in the other direction to prevent noise. . However, in such a method,
If there is a signal on one side, the above (insertion loss +
Because of the loss (7dB), the signal from the other side cannot be transmitted, resulting in so-called truncations at the beginning and end of speech. To solve this problem, a bidirectional amplifier has been proposed that uses an echo canceller to cancel the echo signal at the 2-wire/4-wire conversion point and reduce the closed loop gain. However, in a bidirectional amplifier that uses an echo canceller, no cutting occurs at the beginning or end of speech, but due to the nature of the echo canceller,
When the line is changed, it takes time to adjust the echo canceller in order to obtain a certain amount of echo cancellation, and there is a drawback that it is almost impossible to make a call during this echo canceller adjustment time.

[Purpose of the invention]

本発明の目的は、上述の欠点を除去したエコー
キヤンセラ型双方向増幅器を提供することにあ
る。 SUMMARY OF THE INVENTION An object of the present invention is to provide an echo canceller-type bidirectional amplifier that eliminates the above-mentioned drawbacks.

[Structure of the invention]

本発明の双方向増幅器は２線回線を４線回線に
変換する２つの２線４線変換回路と、この２線４
線変換回路で変換された４線受信側より４線送信
側への反響信号を消去する２つのエコーキヤンセ
ラを有する２線双方向増幅器において、前記２つのエコーキヤンセラの受信入力レベル
と送信出力レベルとの差をそれぞれ検出し、その
検出量をERL1，ERL2とする第１および第２の
打ち消し量検出回路と、前記２つのエコーキヤンセラの間に配置され外
部制御信号によつて利得または損失を与えること
ができる第１および第２の可変利得増幅回路と、これら第１および第２の可変利得増幅回路の利
得のうちの一方を利得G_Vとして選択する選択回
路と、この選択された利得G_Vと前記第１および第２
の検出出力ERL1およびERL2と鳴音余裕ｍに基
づいて前記４線回路のループ利得が負になるよう
前記他方の利得G_NVを求める手段と、前記２つのエコーキヤンセラの送信出力レベル
を比較し、送信出力が大と判定された前記可変利
得増幅回路に対して前記利得G_Vを外部制御信号
として供給し、前記送信出力が小として判定され
た前記他方の可変利得増幅回路に対して前記利得
G_Vと前記利得G_NVの小さい方を供給する制御回路
とから構成されたことを特徴としている。 The bidirectional amplifier of the present invention includes two 2-wire and 4-wire conversion circuits that convert a 2-wire line into a 4-wire line;
In a 2-wire bidirectional amplifier having two echo cancellers that eliminate echo signals from the 4-wire receiving side to the 4-wire transmitting side converted by a line conversion circuit, the receiving input level and the transmitting output of the two echo cancellers are as follows: First and second cancellation amount detection circuits each detect the difference from the level and use the detected amounts as ERL1 and ERL2, and are arranged between the two echo cancellers and control the gain or loss according to an external control signal. a selection circuit that selects one of the gains of the first and second variable gain amplifier circuits as the gain _GV ; and the selected gain G _V and said first and second
means for determining the other gain _GNV so that the loop gain of the four-wire circuit becomes negative based on the detection outputs ERL1 and ERL2 and the sound margin m, and comparing the transmission output levels of the two echo cancellers. , the gain G V is supplied as an external control signal to the variable gain amplifier circuit whose transmission output is determined to be large, and the gain G _V is supplied to the other variable gain amplifier circuit whose transmission output is determined to be small.
It is characterized in that it is comprised of a control circuit that supplies the smaller of the gains _GV and the gain _GNV .

〔Example〕

次に図面を参照して本発明を説明する。第１図
および第２図は本発明の一実施例を示すブロツク
図である。図において、増幅器３０，３１では、
高速応答のAGC付きで、入力信号の長時間平均
レベルを検出して、出力信号の長時間平均レベル
を、ある目的のレベルとなるように、利得G₁，
G₂（dB）が推定される。一方、打ち消し量検出回
路５０，５１は、エコーキヤンセラ２０，２１の
送信出力信号と受信入力信号のレベルP_SO，P_RI
（dB）から、２線・４線変換回路を含めたエコー
キヤンセラの打ち消し量ERLを ERL＝P_RI−P_SO（dB）として求める。ただし、打消し量ERLを測定で
きるのは、受信入力信号として、十分大きなレベ
ルの信号が入力し、送信出力信号としては、受信
入力信号の２線・４線変換回路１０，１１のまわ
り込み分のみが出力される場合でこれをシング
ル・トーク状態と呼んでいる。しかし、完全にシ
ングル・トーク状態を見分けることは困難なた
め、 P_SO＜P_RI が一定時間以上継続して成り立つ時をシングルト
ークと判断し、この時の打消量ERLを真の打消
し量ERLとして保持する。なお、打ち消し量検
出回路５０，５１で検出した打ち消し量を
ERL1，ERL2とする。優勢側利得制御回路６０
は、増幅器３０，３１で求まつた利得G₁，G₂の
中の利得の小さい方を優勢側利得G_Vとして求め
る。 Next, the present invention will be explained with reference to the drawings. 1 and 2 are block diagrams showing one embodiment of the present invention. In the figure, in amplifiers 30 and 31,
Equipped with a high-speed response AGC, it detects the long-term average level of the input signal and adjusts the gain G ₁ , so that the long-term average level of the output signal reaches a certain target level.
G ₂ (dB) is estimated. On the other hand, the cancellation amount detection circuits 50 and 51 detect the levels P _SO and P _RI of the transmission output signals and reception input signals of the echo cancellers 20 and 21.
(dB), find the cancellation amount ERL of the echo canceller including the 2-wire/4-wire conversion circuit as ERL = P _RI − P _SO (dB). However, the amount of cancellation ERL can be measured only when a sufficiently large level signal is input as the received input signal, and when the transmitted output signal is the amount of the received input signal wrapped around the 2-wire/4-wire conversion circuits 10 and 11. This is called a single talk state. However, since it is difficult to completely distinguish between single talk states, single talk is determined when P _SO < P _RI continues for a certain period of time, and the amount of cancellation ERL at this time is calculated as the true amount of cancellation ERL. hold as. Note that the amount of cancellation detected by the amount of cancellation detection circuits 50 and 51 is
Let them be ERL1 and ERL2. Dominant side gain control circuit 60
The smaller of the gains G ₁ and G ₂ found in the amplifiers 30 and 31 is determined as the dominant side gain G _V .

G_V＝min（G₁，G₂）次に劣勢側利得制御回路７０は、優勢側に利得
G_Vを与えた時に鳴音が起こらないように、劣勢
側利得G_NVを次のとおり求める。 G _V = min (G ₁ , G ₂ ) Next, the inferior side gain control circuit 70 applies a gain to the dominant side.
Find the inferior side gain G _NV as follows so that no noise occurs when G _V is given.

G_NV＋G_V−ERL1−ERL2＜−ｍここでｍは鳴音余裕である。このように劣勢側
利得G_NVは打消し量ERLが小さい時には負になる
場合すなわち損失になる場合もある。また打消し
量ERLが大きく、利得G_Vが小さい時には、G_V＜
G_NVとなつても、鳴音は生じないが、この場合に
は、不必要に大きな利得が劣勢側に挿入される。 G _NV +G _V −ERL1−ERL2<−m Here, m is the noise margin. In this way, the inferior side gain _GNV may become negative when the amount of cancellation ERL is small, that is, it may become a loss. Furthermore, when the amount of cancellation ERL is large and the gain G _V is small, G _V <
Even if G _NV occurs, no sound is generated, but in this case, an unnecessarily large gain is inserted into the inferior side.

このため、劣勢側利得G_NVとしてはG_Vと
（ERL1＋ERL2−G_V−ｍ）の中の小さい方を選択
する。 Therefore, the smaller of G _V and (ERL1+ERL2−G _V −m) is selected as the inferior gain G _NV .

G_NV＝min（G_V，ERL1＋ERL2−G_V−ｍ）音声優勢検出回路８０は増幅器３０，３１の入
力信号のレベルを検出比較し、音量が大きいと判
定した優勢側の増幅器に利得G_Vを与え、音量の
小さい劣勢側の増幅器の利得をG_NVを与えてい
る。G _NV = min (G _V , ERL1 + ERL2 − G _V −m) The audio dominance detection circuit 80 detects and compares the levels of the input signals of the amplifiers 30 and 31, and applies a gain G _V to the dominant amplifier that has been determined to have a higher volume. The gain of the amplifier on the less powerful side with the lower volume is given as G _NV .

〔発明の効果〕以上のように本発明では、回線接続と同時に増
幅器の高速応答AGCを動作させ、必要な反響打
ち消し量が得られない間は音声信号の劣勢側に損
失を与えて鳴音を防止しているのでエコーキヤン
セラの同定終了前でも通話が可能となる。[Effects of the Invention] As described above, in the present invention, the high-speed response AGC of the amplifier is activated at the same time as the line is connected, and while the necessary amount of echo cancellation cannot be obtained, a loss is given to the inferior side of the audio signal to suppress the sound. Since this is prevented, it is possible to make a call even before the echo canceller identification is completed.

[Brief explanation of the drawing]

第１図は本発明の一実施例を示すブロツク図お
よび第２図は本発明の一部の詳細を示す図であ
る。第１，２図において、１，２……入出力端子、
１０，１１……２線４線変換回路、２０，２１…
…エコーキヤンセラ、３０，３１……AGC付き
増幅器、４０……利得制御回路、５０，５１……
打ち消し量検出回路、６０……優勢側利得制御回
路、７０……劣勢側利得制御回路、８０……音声
優勢検出回路。 FIG. 1 is a block diagram showing one embodiment of the invention, and FIG. 2 is a diagram showing some details of the invention. In Figures 1 and 2, 1, 2...input/output terminals,
10, 11... 2-wire 4-wire conversion circuit, 20, 21...
...Echo canceller, 30, 31...Amplifier with AGC, 40...Gain control circuit, 50, 51...
Cancellation amount detection circuit, 60... dominant side gain control circuit, 70... inferior side gain control circuit, 80... voice dominance detection circuit.

Claims

[Claims] 1. Two 2-wire lines 4 for converting a 2-line line into a 4-line line
A 2-wire bidirectional amplifier having a line conversion circuit and two echo cancellers for canceling echo signals from the 4-wire receiving side to the 4-wire transmitting side converted by the 2-wire and 4-wire converting circuit, disposed between the two echo cancellers and first and second cancellation amount detection circuits that respectively detect the difference between the reception input level and the transmission output level of the canceller and use the detected amounts as ERL1 and ERL2. first and second variable gain amplifier circuits that can provide gain or loss according to an external control signal; and selecting one of the gains of the first and second variable gain amplifier circuits as gain _GV . a selection circuit, the selected gain G _V and the first and second
means for determining the other gain _GNV so that the loop gain of the four-wire circuit becomes negative based on the detection outputs ERL1 and ERL2 and the sound margin m; and comparing the transmission output levels of the two echo cancellers. The gain G V is supplied as an external control signal to the variable gain amplifier circuit whose transmission output is determined to be large, and the gain G _V is supplied as an external control signal to the variable gain amplifier circuit whose transmission output is determined to be small. gain
1. An echo canceller type bidirectional amplifier comprising a control circuit that supplies the smaller of _GV and the gain _GNV .