JPH0134408B2 - - Google Patents
Info
- Publication number
- JPH0134408B2 JPH0134408B2 JP57002061A JP206182A JPH0134408B2 JP H0134408 B2 JPH0134408 B2 JP H0134408B2 JP 57002061 A JP57002061 A JP 57002061A JP 206182 A JP206182 A JP 206182A JP H0134408 B2 JPH0134408 B2 JP H0134408B2
- Authority
- JP
- Japan
- Prior art keywords
- output
- audio
- input
- feedback
- voltage
- 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.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M9/00—Arrangements for interconnection not involving centralised switching
- H04M9/08—Two-way loud-speaking telephone systems with means for conditioning the signal, e.g. for suppressing echoes for one or both directions of traffic
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/32—Automatic control in amplifiers having semiconductor devices the control being dependent upon ambient noise level or sound level
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/60—Substation equipment, e.g. for use by subscribers including speech amplifiers
- H04M1/6008—Substation equipment, e.g. for use by subscribers including speech amplifiers in the transmitter circuit
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Control Of Amplification And Gain Control (AREA)
Description
【発明の詳細な説明】
この発明は、例えば送話器（マイク）等を介し
て入力される音声信号の入力レベルに応じてその
音声増幅器の増幅度を制御して、周囲雑音の影響
を軽減する送話装置に関するものである。[Detailed Description of the Invention] This invention reduces the influence of ambient noise by controlling the amplification degree of an audio amplifier according to the input level of an audio signal input via a transmitter (microphone), etc. The present invention relates to a transmitting device.
一般に、音声信号を増幅する音声増幅器は、そ
の入力レベルに比例した音声信号を出力する。 Generally, an audio amplifier that amplifies an audio signal outputs an audio signal proportional to its input level.
ところで、送話器から出力される音声信号を増
幅する場合、送話中は送話者の声が比較的強い音
圧として送話器に入力されるため、周囲の雑音は
その音声にマイクされ、多少騒々しくても気には
ならない。 By the way, when amplifying the audio signal output from a transmitter, the speaker's voice is input to the transmitter as a relatively strong sound pressure during transmission, so surrounding noise is microphoned into the voice. , I don't mind if it's a little noisy.
しかし、送話を中断した時は、周囲雑音のみと
なりそれがそのまま増幅出力されるので、送話時
に比べ耳ざわりなものとなる。特に車載用の送話
装置においては、エンジン音等の低い周波数成分
の周囲雑音が強調されるため余計に耳ざわりなも
のとなる。 However, when the transmission is interrupted, there is only ambient noise, which is amplified and output as it is, making it more jarring than when the transmission is being made. Particularly in a vehicle-mounted transmitter, ambient noise with low frequency components, such as engine noise, is emphasized, making it even more annoying.
この発明はこのような従来のものの欠点を除去
するためになされたもので、送話器に非直線性の
入・出力特性をもたせると共にその入・出力特性
に周波数特性をもたせることにより周囲雑音の影
響を軽減できる送話器を提供することを目的とし
ている。 This invention was made in order to eliminate the drawbacks of the conventional devices, and it reduces ambient noise by providing a transmitter with non-linear input/output characteristics and giving frequency characteristics to the input/output characteristics. The purpose is to provide a transmitter that can reduce the impact.
以下この発明の一実施例について説明する。第
１図において、１は入力される音声波を電気信号
（音声信号）に変換する送話器、２は送話器１の
音声出力を整流するに充分なレベルまで増幅する
ための増幅器、３はこの増幅された音声信号を遮
断周波数約1KHzで高域濾波（通過）する高域濾
波器、４はこの濾波出力を整流する整流回路で、
整流回路４出力はR1、C1、R2で構成される平滑
回路５でリツプル分が除去される。６は電圧比較
器で、電圧比較点を設定するための可変抵抗器
RVを備えており、この設定電圧を前記平滑回路
５からの電圧を比較してその状態に従つて高レベ
ルあるいは低レベルの信号を出力する。７は音声
帰還増幅器であり演算増幅器で形成された音声増
幅器８と、帰還抵抗Ra（又はRb）、入力抵抗器Ri
で形成される帰還回路９、およびこの帰還抵抗
Ra、Rbを切換接続するアナログスイツチ１０に
より構成されている。なお、このアナログスイツ
チ１０は前記電圧比較器６の出力により切換制御
されるよう接続されている。 An embodiment of this invention will be described below. In FIG. 1, 1 is a transmitter that converts input audio waves into electrical signals (audio signals), 2 is an amplifier for amplifying the audio output of the transmitter 1 to a level sufficient to rectify it, and 3 4 is a high-pass filter that high-pass filters (passes) this amplified audio signal at a cut-off frequency of about 1 KHz, and 4 is a rectifier circuit that rectifies this filtered output.
Ripples from the output of the rectifier circuit 4 are removed by a smoothing circuit 5 composed of R 1 , C 1 , and R 2 . 6 is a voltage comparator, and a variable resistor for setting the voltage comparison point
The set voltage is compared with the voltage from the smoothing circuit 5, and a high level or low level signal is output according to the condition. 7 is an audio feedback amplifier, which includes an audio amplifier 8 formed of an operational amplifier, a feedback resistor Ra (or Rb), and an input resistor Ri.
a feedback circuit 9 formed by
It is composed of an analog switch 10 that switches and connects Ra and Rb. The analog switch 10 is connected so as to be controlled by the output of the voltage comparator 6.
第２図は第１図の送話装置の入出力特性を示す
ものであり、横軸は送話器１に加えられる入力音
圧Pi、縦軸は音声帰還増幅器７の出力電圧Voで
ある。 FIG. 2 shows the input/output characteristics of the transmitter shown in FIG. 1, where the horizontal axis is the input sound pressure Pi applied to the transmitter 1, and the vertical axis is the output voltage Vo of the audio feedback amplifier 7.
次に、第１図の動作を第２図を用いて説明す
る。第１図において、今、音声が送話器１に加え
られると、送話器１の音声出力が適当なレベルに
まで増幅器２により増幅される。この増幅出力は
高域濾波器３に入力されるがこの遮的周波数は約
1KHzに選ばれているため音声成分はそのまま高
域濾波器３を通過し、整流回路４および平滑回路
５を介して整流、平滑される。ここで、電圧比較
器６の可変抵抗器RVにより設定される基準電圧
Eaは、送話時の入力音圧レベルPiがPaレベル時、
平滑回路５より出力される出力電圧と等しくなる
よう設定されている。また送話時の入力音圧Piが
Paよりも大きい場合は、電圧比較器６の出力は
アナログスイツチ１０を帰還抵抗Ra側に切換接
続し、入力音圧PiがPaよりも低い場合は、帰還
抵抗Rb側に切換接続されるものとする。ここで、
Ra＞Rbとすれば音声帰還増幅器７の利得は
20logRa／Ri＞20logRb／Ri
となり、その利得差すなわち出力レベル差は
（Va−Vb）dBとなる。 Next, the operation shown in FIG. 1 will be explained using FIG. 2. In FIG. 1, when voice is now applied to the handset 1, the voice output of the handset 1 is amplified by the amplifier 2 to an appropriate level. This amplified output is input to the high-pass filter 3, but this cutoff frequency is approximately
Since the frequency is selected to be 1 KHz, the audio component passes through the high-pass filter 3 as it is, and is rectified and smoothed via the rectifier circuit 4 and the smoothing circuit 5. Here, the reference voltage set by the variable resistor RV of the voltage comparator 6
Ea is when the input sound pressure level Pi during transmission is Pa level,
It is set to be equal to the output voltage output from the smoothing circuit 5. Also, the input sound pressure Pi during transmission is
When the input sound pressure Pi is higher than Pa, the output of the voltage comparator 6 is switched to the feedback resistor Ra side of the analog switch 10, and when the input sound pressure Pi is lower than Pa, the output of the voltage comparator 6 is switched to the feedback resistor Rb side. do. here,
If Ra > Rb, the gain of the audio feedback amplifier 7 will be 20logRa/Ri>20logRb/Ri, and the gain difference, that is, the output level difference will be (Va - Vb) dB.
従つて、送話器１に入力される1KHz以上の周
囲雑音の雑音レベルPN1をPN1＜Paとし、一方
送話時における音圧レベルPsをPs＞Paとすると、
送話時は非送話時（雑音入力時）に比べ、音声帰
還増幅器７の出力Voは（Va−Vb）dBだけ増加
する。すなわち従来のものに比べ周囲雑音による
聞きづらさは相対的に（Va−Vb）dBだけ改善
される。 Therefore, if the noise level PN 1 of the ambient noise of 1 KHz or higher inputted to the transmitter 1 is PN 1 <Pa, and on the other hand, the sound pressure level Ps during transmission is Ps > Pa,
During speech transmission, the output Vo of the audio feedback amplifier 7 increases by (Va-Vb) dB compared to when speech is not transmitted (noise input). In other words, the difficulty of hearing due to ambient noise is relatively improved by (Va - Vb) dB compared to the conventional one.
以上の1KHz以上の音圧の入出力特性は第２図
の特性Ａで示してある。 The above input/output characteristics for sound pressures of 1 KHz or higher are shown by characteristic A in FIG.
ところで、周波数成分が1KHzより低い周囲雑
音のような場合、高域濾波器３により減衰させら
れるため、音声帰還増幅器７が高利得の状態にな
るにはその雑音音圧レベルPN2は第２図に示す
Pcまで大きくしなければならない。つまり1KHz
以下の雑音周波数に対してはその周波数が低くな
ればなるほどPaより更に大きい音圧になるまで
音声帰還増幅器７の利得が低く保たれるため、例
えば、自動車に搭載するような送話装置では、こ
のような1KHz以下の雑音を除去するのに非常に
効果的である。第２図の場合、1KHz以下の雑音
に対する余裕度は高域濾波器３の濾波特性により
決定され、入力音圧に換算すれば第２図の（Pc
−Pa）dBに相当する。 By the way, in the case of ambient noise whose frequency component is lower than 1 KHz, it is attenuated by the high-pass filter 3, so in order for the audio feedback amplifier 7 to be in a high gain state, the noise sound pressure level PN 2 must be as shown in Fig. 2.
I have to enlarge it to PC. That is 1KHz
For the following noise frequencies, as the frequency becomes lower, the gain of the audio feedback amplifier 7 is kept low until the sound pressure becomes even higher than Pa. For example, in a transmitting device installed in a car, It is very effective in removing such noise below 1KHz. In the case of Figure 2, the margin for noise below 1KHz is determined by the filtering characteristics of the high-pass filter 3, and if converted to input sound pressure, the margin for noise below 1KHz is
-Pa) dB.
また送話器入力がPN→PsまたはPs→PNに急
激に変化した時の平滑回路５のステツプ応答すな
わちアナログスイツチ１０の切換応答時間はR1、
C1、R2の値により決定される。そこでこの入力
レベルの変動による音声の立上がり時の語頭切れ
を防ぐためにR1C1＝t1を短かく、また送話中の語
勢の弱くなつたところでの出力の急激な減少をで
きるだけ少なくするようR2C1＝t2を長くするため
にR1＜R2に選定しておく。 Furthermore, the step response of the smoothing circuit 5 when the transmitter input suddenly changes from PN to Ps or from Ps to PN, that is, the switching response time of the analog switch 10, is R 1 ,
It is determined by the values of C 1 and R 2 . Therefore, in order to prevent the beginning of a word from being cut off at the beginning of the voice due to fluctuations in the input level, R 1 C 1 = t 1 should be shortened, and the sudden decrease in output when the tone of speech becomes weak during transmission should be minimized. In order to make R 2 C 1 = t 2 long, R 1 < R 2 is selected.
ところで入力音圧PiがPaの近傍で変動すると、
出力電圧VoがVaVbとなるいわゆるチヤタリ
ング現象を生じる。これを防ぐために第３図のよ
うに電圧比較器６の出力から帰還抵抗Rfを介し
て入力に帰還をかけ電圧比較器６にヒステリシス
特性をもたせることにより実現できる。 By the way, when the input sound pressure Pi fluctuates around Pa,
A so-called chattering phenomenon occurs in which the output voltage Vo becomes VaVb. In order to prevent this, this can be realized by applying feedback from the output of the voltage comparator 6 to the input via the feedback resistor Rf, as shown in FIG. 3, to give the voltage comparator 6 a hysteresis characteristic.
第４図は第３図の入出力特性を示すもので、送
話時において、一度入力音圧がPa以上になれば
音圧がPb以下になるまでは音声帰還増幅器７の
利得はそのまま保たれるので、第１図に示した送
話装置に比べ送話中の音圧の強弱による音声帰還
増幅器７の利得変化の機会が少なく、より自然な
会話を続けることができる。このヒステリシスの
量（Pa−Pb）dBの電圧比較器６の帰還抵抗Rfと
可変抵抗器RVの比により決定することができ
る。 Figure 4 shows the input/output characteristics shown in Figure 3. During voice transmission, once the input sound pressure exceeds Pa, the gain of the audio feedback amplifier 7 remains unchanged until the sound pressure falls below Pb. Therefore, there is less opportunity for the gain of the audio feedback amplifier 7 to change due to the strength of the sound pressure during transmission compared to the speech transmission device shown in FIG. 1, and a more natural conversation can be continued. The amount of hysteresis (Pa-Pb) in dB can be determined by the ratio of the feedback resistor Rf of the voltage comparator 6 and the variable resistor RV.
また上記実施例では、音声帰還増幅器７の帰還
定数をRa、又はRbの抵抗器のみで示したが音声
帰還増幅器７に周波数特性を持たせるには第５図
に示すようにその帰還回路９を抵抗器とコンデン
サを組合せることにより可能となる。この場合の
入出力特性の一例を第６図に示す。 Further, in the above embodiment, the feedback constant of the audio feedback amplifier 7 is shown using only the resistor Ra or Rb, but in order to give the audio feedback amplifier 7 a frequency characteristic, the feedback circuit 9 is required as shown in FIG. This is possible by combining a resistor and a capacitor. An example of the input/output characteristics in this case is shown in FIG.
以上のようにこの発明によれば送話器出力を高
域濾波器を通し、整流、平滑する回路を設け、こ
の出力と予め設定された電圧と比較する電圧比較
器の出力により音声帰還増幅器の帰還量を制御
し、通常の送話の時はこの音声増幅器の利得を上
げ、周囲雑音だけの時の様に入力音圧の低い時や
入力音圧が高くても車に搭載した時のように周波
数成分の低い時に音声帰還増幅器の利得を下げる
よう構成したので周囲雑音による耳ざわりな雑音
を軽減でき、特に車載用のものについては、その
エンジン音等の低周波雑音を効果的に除去するこ
とができる。 As described above, according to the present invention, a circuit for rectifying and smoothing the transmitter output through a high-pass filter is provided, and the output of the voltage comparator that compares this output with a preset voltage is used to control the voice feedback amplifier. By controlling the amount of feedback, the gain of this audio amplifier is increased during normal transmission, and when the input sound pressure is low, such as when there is only ambient noise, or when the input sound pressure is high, such as when installed in a car. Since the gain of the audio feedback amplifier is lowered when the frequency component is low, it is possible to reduce the harsh noise caused by ambient noise, and especially for automotive applications, it is possible to effectively remove low frequency noise such as engine sound. Can be done.
さらに音声の語頭切れを防止し、しや断周波数
近辺におけるチヤタリングを防止して、送話出力
の全体的な音質を向上させることができる。 Furthermore, it is possible to prevent the beginning of the voice from being cut off and to prevent chattering near the cut-off frequency, thereby improving the overall sound quality of the transmitted speech output.
第１図はこの発明の一実施例による送話装置の
概略ブロツク図、第２図は第１図の入出力特性を
示す特性図、第３図はこの発明の一実施例を示す
もので、ヒステリシス特性をもつた送話装置のブ
ロツク図、第４図は第３図の入出力特性の１例を
示す特性図、第５図はこの発明の他の実施例を示
すもので、音声帰還増幅器に周波数特性を持たせ
た場合のブロツク図、第６図は第５図の入出力特
性を示す特性図である。
１は送話器、２は音声増幅器、３は高域濾波
器、４は整流回路、５は平滑回路、６は電圧比較
器、７は音声帰還増幅器、８は音声増幅器、９は
帰還回路、１０はアナログスイツチである。な
お、図中同一符号は同一又は相当する部分を示
す。
FIG. 1 is a schematic block diagram of a transmitter according to an embodiment of the invention, FIG. 2 is a characteristic diagram showing the input/output characteristics of FIG. 1, and FIG. 3 is a diagram showing an embodiment of the invention. A block diagram of a transmitter having hysteresis characteristics, FIG. 4 is a characteristic diagram showing an example of the input/output characteristics of FIG. 3, and FIG. 5 is a diagram showing another embodiment of the present invention. FIG. 6 is a characteristic diagram showing the input/output characteristics of FIG. 5. 1 is a transmitter, 2 is an audio amplifier, 3 is a high-pass filter, 4 is a rectifier circuit, 5 is a smoothing circuit, 6 is a voltage comparator, 7 is an audio feedback amplifier, 8 is an audio amplifier, 9 is a feedback circuit, 10 is an analog switch. Note that the same reference numerals in the figures indicate the same or corresponding parts.
Claims (1)
る音声信号を増幅する音声帰還増幅器、上記音声
信号成分のうち低周波域の周囲雑音信号成分を減
衰させる濾波器、この濾波器出力を整流する整流
回路、この整流出力を立上り（充電）時間を立下
り（放電）時間より短くなるようにして平滑する
平滑回路、この平滑出力電圧をあらかじめ定めら
れた基準電圧と比較して２状態信号を出力すると
ともに、出力にヒステリシス特性を有する電圧比
較器を備え、 上記電圧比較器の出力に応じて上記音声帰還増
幅器の帰還量を制御することを特徴とする送話装
置。 ２ 濾波器はほぼ1KHz以上を通過させる高域濾
波器で形成されたことを特徴とする特許請求の範
囲第１項記載の送話装置。[Claims] 1. An audio feedback amplifier that has a feedback circuit that controls the degree of amplification and amplifies an input audio signal; a filter that attenuates an ambient noise signal component in a low frequency range among the audio signal components; A rectifier circuit that rectifies this filter output, a smoothing circuit that smoothes this rectified output so that the rise (charging) time is shorter than the fall (discharge) time, and this smoothed output voltage is compared with a predetermined reference voltage. What is claimed is: 1. A transmitting device, comprising: a voltage comparator having a hysteresis characteristic at its output; and controlling a feedback amount of the audio feedback amplifier according to an output of the voltage comparator. 2. The transmitting device according to claim 1, wherein the filter is formed of a high-pass filter that passes approximately 1 KHz or more.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP206182A JPS58119214A (en) | 1982-01-09 | 1982-01-09 | Transmitter |
| US06/453,545 US4506381A (en) | 1981-12-29 | 1982-12-27 | Aural transmitter device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP206182A JPS58119214A (en) | 1982-01-09 | 1982-01-09 | Transmitter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS58119214A JPS58119214A (en) | 1983-07-15 |
| JPH0134408B2 true JPH0134408B2 (en) | 1989-07-19 |
Family
ID=11518821
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP206182A Granted JPS58119214A (en) | 1981-12-29 | 1982-01-09 | Transmitter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS58119214A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4628529A (en) * | 1985-07-01 | 1986-12-09 | Motorola, Inc. | Noise suppression system |
| US4630304A (en) * | 1985-07-01 | 1986-12-16 | Motorola, Inc. | Automatic background noise estimator for a noise suppression system |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56128720U (en) * | 1980-02-28 | 1981-09-30 |
-
1982
- 1982-01-09 JP JP206182A patent/JPS58119214A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS58119214A (en) | 1983-07-15 |
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