JPH01253353A - Howling canceler system for hand-free telephone - Google Patents
Howling canceler system for hand-free telephoneInfo
- Publication number
- JPH01253353A JPH01253353A JP8009488A JP8009488A JPH01253353A JP H01253353 A JPH01253353 A JP H01253353A JP 8009488 A JP8009488 A JP 8009488A JP 8009488 A JP8009488 A JP 8009488A JP H01253353 A JPH01253353 A JP H01253353A
- Authority
- JP
- Japan
- Prior art keywords
- signal
- speech
- priority mode
- mode
- transmitting
- 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
- 230000005540 biological transmission Effects 0.000 claims abstract description 43
- 238000000034 method Methods 0.000 claims description 56
- 230000005236 sound signal Effects 0.000 claims description 2
- 238000010586 diagram Methods 0.000 description 6
- 230000007704 transition Effects 0.000 description 5
- 230000002238 attenuated effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000004043 responsiveness Effects 0.000 description 1
Abstract
Description
【発明の詳細な説明】
〔概要〕
マイクとスピーカを使用するハンズフリー電話のハウリ
ングを防止するキャンセラ方式において、送受話共に無
信号状態では受話信号を減衰させる送話優先モードとし
て、周囲の雑音等による不要なモード切替えを回避する
。[Detailed Description of the Invention] [Summary] In a canceller method that prevents howling in hands-free telephones that use a microphone and speaker, a transmitting priority mode that attenuates the received signal when there is no signal for both transmitting and receiving calls is used to suppress ambient noise, etc. Avoid unnecessary mode switching.
本発明は、ハンズフリー電話のハウリングを防止するハ
ウリングキャンセラ方式に関する。The present invention relates to a howling canceller method for preventing howling in a hands-free telephone.
マイクとスピーカを使用するハンズフリー（Ｈ／Ｆ）電
話では、通話中にスピーカからの音がマイクに回り込ん
でハウリングを起こすことを防止するために、送話信号
のレベルが高いときは受話信号を減衰させ（送話優先モ
ード）、逆に受話信号のレベルが高いときは送話信号を
減衰させる（受話優先モード）ハウリングキャンセラ方
式を採用することがある。On hands-free (H/F) telephones that use a microphone and speaker, to prevent the sound from the speaker from reaching the microphone during a call and causing howling, the receiving signal is switched off when the level of the transmitting signal is high. A howling canceller method is sometimes adopted, in which the level of the received signal is attenuated (sending priority mode) and, conversely, the transmitting signal is attenuated (receiving priority mode) when the level of the received signal is high.
この方式で問題となるのは、通話中に送受話共に無信号
となった場合である。この様な場合に従来は、（１）直
前のモードを維持するか、（２）受話優先モードに統一
するようにしている。A problem with this method occurs when there is no signal for both transmitting and receiving calls during a call. In such cases, conventional methods are to (1) maintain the previous mode or (2) unify to the receive priority mode.
しかしながら、（１）の方法では電子ボリウムによる減
衰量の差によってバックノイズが聞こえる場合と聞こえ
ない場合が生じ、違和感がある。また、（２）の方法で
はＣＰＵのアナログ入力レベルのスレッシェホールド付
近で走行ノイズやブロア雑音等を拾い、−時的に送話優
先モードとなり再び受話優先モードとなる。即ち、優先
モードが送話と受話で頻繁に切替わる欠点がある。However, with method (1), the background noise may be audible or not due to the difference in the amount of attenuation caused by the electronic volume, giving a sense of discomfort. Furthermore, in the method (2), running noise, blower noise, etc. are picked up near the threshold of the analog input level of the CPU, and the mode temporarily changes to the transmit priority mode and then returns to the receive priority mode. That is, there is a drawback that the priority mode frequently switches between sending and receiving calls.
本発明では送受話共に無信号となったら送話優先モード
に統一することで、上述した問題点を解決しようとする
ものである。The present invention attempts to solve the above-mentioned problem by unifying the transmitting priority mode when there is no signal for both transmitting and receiving calls.
第１図は本発明の基本構成図で、１は送話音を送話信号
Ｔに変換するマイク、２は受話信号Ｒを受話音に変換す
るスピーカ、３はＨ／Ｆ制御装置である。この図はＨ／
Ｆ自動車電話を例としているので、一般の回線網とは無
線回線を通して結合される。４はそのための無線機（Ｔ
／Ｕ）である。FIG. 1 is a basic configuration diagram of the present invention, in which numeral 1 is a microphone that converts a transmitted voice sound into a transmitted voice signal T, 2 is a speaker that converts a received voice signal R into a received voice sound, and 3 is an H/F control device. This figure is H/
Since the F car phone is used as an example, it is connected to the general network through a wireless line. 4 is a radio device for that purpose (T
/U).
Ｈ／Ｆ制御装置３には信号Ｔ、Ｒを個々に減衰させ得る
電子ボリウム３１と、減衰前の信号Ｔ。The H/F control device 3 includes an electronic volume 31 that can individually attenuate the signals T and R, and a signal T before attenuation.
Ｒのレベルを検出して該電子ボリウムを制御し、送話優
先モードと受話優先モードの切替えを行うマイクロコン
ピュータ（ＣＰＵ）３２とが含まれる。A microcomputer (CPU) 32 is included that detects the level of R, controls the electronic volume, and switches between a transmitting priority mode and a receiving priority mode.
一般的な優先モードの設定は、信号Ｔ、 Ｒのレベルを
比較し、いずれか低いレベルの（非優先の）信号を更に
減衰させることにより行う。例えば第２図のように受話
信号Ｒがあり、送話信号Ｔがない状態では送話減衰量を
最大（Ｍａｘ）にし、受話減衰量を最小（Ｍｉｎ）にす
る。これが受話優先モードである。A general priority mode is set by comparing the levels of signals T and R, and further attenuating whichever signal has a lower level (non-priority). For example, as shown in FIG. 2, when there is a reception signal R and no transmission signal T, the transmission attenuation is set to the maximum (Max) and the reception attenuation is set to the minimum (Min). This is the receive priority mode.
これに対し送話信号Ｔも受話信号Ｒもない無信号状態に
なったら、直前のモードには関係なく、送話減衰量をＭ
ｉｎにし、受話減衰量をＭａｘにする送話優先モードに
切替える。このときｔｓｅｃの保護時間を設ける、即ち
無信号状態がｔｓｅｃ間続いた時に送話優先モードに切
換えるようにすると瞬間的な無信号状態による受話−送
話−受話という頻繁なモード切替えを回避できる。また
、減衰量変化を徐々に行うことで、減衰量急変による切
断音の発生を防止でき、また、バックノイズ量の急変が
なくなるため異和感をなくすことができる。On the other hand, when there is no signal, with neither transmitting signal T nor receiving signal R, the transmitting attenuation amount is set to M, regardless of the previous mode.
in, and switch to the transmit priority mode, which sets the receive attenuation amount to max. At this time, if a protection time of tsec is provided, that is, if the no-signal state continues for tsec, the mode is switched to the send priority mode, thereby avoiding frequent mode switching of receive-send-receive due to a momentary no-signal state. Furthermore, by gradually changing the amount of attenuation, it is possible to prevent cutting noise from occurring due to a sudden change in the amount of attenuation, and also to eliminate a sense of strangeness because there is no sudden change in the amount of back noise.
第３図は本発明の一実施例を示す構成図で、３１Ｔは送
話信号Ｔを減衰させる電子ボリウム、３１Ｒは受話信号
Ｒを減衰させる電子ボリウム、３３Ｔ、３４Ｔは送話系
のアンプ、３３Ｒ，３４Ｒは受話系のアンプである（但
し、３４Ｒはパワーアンプ）。信号Ｔ、Ｒはアナログ波
形であるので、Ａ／Ｄ変換器３５でデジタル値に変換し
てＣＰＵ３２に取込む。FIG. 3 is a configuration diagram showing an embodiment of the present invention, in which 31T is an electronic volume that attenuates the transmitting signal T, 31R is an electronic volume that attenuates the receiving signal R, 33T and 34T are transmitting system amplifiers, and 33R is an electronic volume that attenuates the receiving signal R. , 34R are receiver amplifiers (34R is a power amplifier). Since the signals T and R are analog waveforms, they are converted into digital values by the A/D converter 35 and taken into the CPU 32.
本例の基本動作は第１図と変らない。但し、音声信号入
力時に第４図（ａ）のように数５ｓｅｃ程度で減衰量を
変化させるとしたら、無信号時には同図（ｂ）のように
数１０ Ｏｎ＋ｓｅｃ程度の時間をかけて緩やかに減衰
量を変化させる。このようにすると、音声入力時には応
答性がよいので音声の頭切れが少なく、また無信号状態
では減衰量変化による違和感を減少させることができる
。尚、第４図のＭａｘとＭｉｎは第２図とは上下逆に示
しである。The basic operation of this example is the same as in FIG. However, if the attenuation amount is changed over several 5 seconds as shown in Figure 4(a) when an audio signal is input, when there is no signal, it will gradually attenuate over several tens of seconds as shown in Figure 4(b). Vary the amount. In this way, the responsiveness is good during voice input, so there is less chance of the voice cutting off at the beginning, and in a no-signal state, it is possible to reduce the sense of discomfort caused by changes in attenuation. Note that Max and Min in FIG. 4 are shown upside down compared to FIG. 2.
第５図（Ａ）〜（Ｄ）は上述したモード切替制御のフロ
ーチャートである。FIGS. 5A to 5D are flowcharts of the mode switching control described above.
第５図（Ａ）はどのモードにするべきか、即ち送信信号
が大きい場合の送信優先モード、受信信号レベルが大き
い場合の受信優先モード、受信信号及び送信信号が無い
場合の送信優先モードのどのモードにすべきかを判断す
る部分のフローチャートである。ステップＳ１では受信
信号Ｔの受信信号レベルＬＲと送信信号Ｒの送信信号レ
ベルＬＴを読み込む。尚、送信信号レベルＬＴ、及び受
信信号レベルＬＲはその時点における瞬間的なしベルで
はなく、積分回路等を用いたハード的なフィルタ、もし
くはプログラムによる数値処理（積分演算等）によるフ
ィルタによりフィルタリングされる。ステップＳ２では
、送信信号レベルＬＴ。Figure 5 (A) shows which mode should be used: transmission priority mode when the transmission signal is large, reception priority mode when the reception signal level is high, and transmission priority mode when there is no reception signal or transmission signal. 12 is a flowchart of a part for determining whether to set the mode. In step S1, the received signal level LR of the received signal T and the transmitted signal level LT of the transmitted signal R are read. Note that the transmitted signal level LT and received signal level LR are not instantaneous at that point in time, but are filtered by a hardware filter using an integrating circuit or the like, or by a filter using numerical processing (integral calculation, etc.) by a program. . In step S2, the transmission signal level LT.
及び受信信号レベルＬＲが共に無信号と判断できる基準
レベルＬＴＬＸＭ、ＬＲＬＸＭ以下の場合に、ステップ
Ｓ３に移る。ステップＳ３では前回の判定が無信号かど
うかを前回の判定を示すフラグＦＭにて判断し、無信号
でなければ、ステップＳ４に移りフラグＦＭを無信号と
するとともに、モード判定の保護時間、即ち所定時間（
例えば５００ｍ５）そのモードが続けばそのモードに移
ったものと判断するためのタイマＴＣをリセットしステ
ップＳ１に戻る。また、前回の判定が無信号モードであ
れば、ステップＳ３からステップＳ５に移り、無信号状
態が所定時間以上績いたかどうかがタイマＴＣにより判
定され、所定時間以上績いたなら第５図（Ｂ）の無信号
モード処理のステップＳ２１に進み、無信号状態の継続
が所定時間以内ならステップＳ１に戻る。ステップＳ２
にて、送信信号レベルＬＴ、または受信信号レベルＬＲ
が基準レベルＬＴＬ８Ｍ、ＬＲＬ１Ｍを越えていると判
断されれば、ステップＳ６に移り、受信信号レベルＬＲ
と送信信号レベルＬＴを比較する。送信信号レベルＬＴ
が大きい場合にはステップＳ７に移り、受信信号レベル
ＬＲが大きい場合にはステップＳ１０に移る。ステップ
Ｓ７では前回の判定が送信かどうかをフラグＦＭにて判
断し、送信でなければ、ステップＳ８に移りフラグＦＭ
を送信とするとともに、モード判定の保護時間、即ち所
定時間（例えば５００ｍ５）そのモードが続けばそのモ
ードに移ったものと判断するためのタイマＴＣをリセッ
トしステップＳ１に戻る。また、前回の判定が無信号で
あれば、ステップＳ７からステップＳ９に移り、送信状
態が所定時間以上績いたかどうかがタイマＴＣにより判
定され、所定時間以上績いたなら第５図（Ｃ）の送信優
先モード処理のステップＳ３１に進み、送信状態の１！
続が所定時間以内ならステップＳ１に戻る。ステップＳ
１０では前回の判定が受信かどうかをフラグＦＭにて判
断し、受信でなければ、ステップＳｌｌに移りフラグＦ
Ｍを受信とするとともに、モード判定の保護時間、即ち
所定時間（例えば５００ｍ５）そのモードが続けばその
モードに移ったものと判断するためタイマＴＣをリセッ
トしステップＳ１に戻る。また、前回の判定が受信であ
ればステップ３１０からステップＳ１２に移り、送信状
態が所定時間以上績いたかどうかがタイマＴＣにより判
定され、所定時間以上績いたなら第５図（Ｄ）の受信優
先モード処理のステップＳ４１に進み、送信状態の継続
が所定時間以内ならステップＳ１に戻る。この制御によ
り、ノイズ等による突発的な送信、及び受信信号のレベ
ル変化に対する不要なモード切換えを防止できる。If both the received signal level LR and the received signal level LR are equal to or lower than the reference levels LTLXM and LRLXM at which it can be determined that there is no signal, the process moves to step S3. In step S3, it is determined whether the previous judgment is no signal or not using the flag FM indicating the previous judgment. If there is no signal, the process moves to step S4, where the flag FM is set to no signal, and the mode judgment protection time, i.e. Predetermined time (
For example, 500 m5) If the mode continues, the timer TC for determining that the mode has been shifted is reset and the process returns to step S1. Further, if the previous determination is the no-signal mode, the process moves from step S3 to step S5, and the timer TC determines whether or not the no-signal state has lasted for a predetermined time or longer, and if the no-signal state has lasted for a predetermined time or longer, as shown in FIG. ), the process proceeds to step S21 of the no-signal mode process, and if the continuation of the no-signal state is within a predetermined time, the process returns to step S1. Step S2
, the transmit signal level LT or the receive signal level LR
If it is determined that the received signal level LR exceeds the reference levels LTL8M and LRL1M, the process moves to step S6, and the received signal level LR
and the transmission signal level LT. Transmission signal level LT
If the received signal level LR is large, the process moves to step S7, and if the received signal level LR is large, the process moves to step S10. In step S7, it is determined whether the previous determination was transmission or not using the flag FM. If it is not transmission, the process moves to step S8 and the flag FM is checked.
is set as a transmission, and a timer TC for determining that the mode has been shifted if the mode continues for a predetermined time (for example, 500 m5) is reset, and the process returns to step S1. Further, if the previous determination is that there is no signal, the process moves from step S7 to step S9, and the timer TC determines whether the transmission state has lasted for a predetermined time or longer. Proceeding to step S31 of the transmission priority mode process, the transmission state is 1!
If the continuation is within the predetermined time, the process returns to step S1. Step S
In step 10, it is determined whether the previous determination was reception or not using flag FM. If it is not reception, the process moves to step Sll and flag F is determined.
M is determined to be received, and if the mode continues for a protection time of mode determination, that is, a predetermined time (for example, 500 m5), it is determined that the mode has been shifted, so the timer TC is reset and the process returns to step S1. Further, if the previous determination is reception, the process moves from step 310 to step S12, and the timer TC determines whether the transmission state has lasted for more than a predetermined time, and if it has been done for more than a predetermined time, priority is given to reception as shown in FIG. 5(D). The process advances to step S41 of the mode process, and if the transmission state continues within a predetermined time, the process returns to step S1. This control can prevent sudden transmission due to noise or the like and unnecessary mode switching in response to changes in the level of the received signal.
第５図（Ｂ）は受信信号Ｔと送信信号Ｒとがともに無い
時の無信号モードの場合の処理を示すフローチャートで
ある。ステップＳ２１では、無信号モードにおける送信
、及び受信信号の減衰量の変化率、即ち電子ボリューム
への制御出力の変化率を規定する時定数ＴＡＩとタイマ
ＴＡとを比較し、タイマＴＡ＞時定数ＴＡＩの時にはス
テップＳ２２に移り、タイルＴＡ≦時定数ＴＡＩの時に
はステップＳ１に戻る。ステップＳ２２ではタイマＴＡ
をリセットし、ステップＳ２３に移る。ステップＳ２３
では、送信路の電子ボリウム３１Ｔのボリウム値ＶＴが
上限値■ＴＭＡｘ かどうか判断し、上限に達してい
なければ、ステップＳ２４に移ってボリウム値ＶＴに１
加算し、ステップＳ２５に移る。また、電子ボリウム３
１Ｔのボリウム値ＶＴが上限値■ＴＭＡＸ であれば、
そのままステップＳ２５に移る。即ち、送信路の減衰量
を徐々に下げていく。ステップＳ２５では、送信路の電
子ボリウム３１Ｒのボリウム値ＶＲが下限値Ｖ ＲＭＩ
Ｎかどうか判断し、下限に達していなければ、ステップ
３２６に移ってボリウム値ＶＲから１減算し、ステップ
Ｓ１に戻る。また、電子ボリウム３１Ｒのボリウム値Ｖ
Ｒが下限値ｖＲＭＩＮであれば、そのままステップＳ１
に戻る。即ち、受信路の減衰量を徐々に上げていく。こ
の制御により、無信号モードにおいて徐々に送話優先モ
ードに移すことができる。この、送話優先モードへの移
行速度は、時定数ＴＡＩの値により調整できる。FIG. 5(B) is a flowchart showing the processing in the no-signal mode when both the received signal T and the transmitted signal R are absent. In step S21, the time constant TAI that defines the rate of change in the amount of attenuation of the transmission and reception signals in the no-signal mode, that is, the rate of change in the control output to the electronic volume, is compared with the timer TA, and the timer TA is determined to be larger than the time constant TAI. When , the process moves to step S22, and when tile TA≦time constant TAI, the process returns to step S1. In step S22, the timer TA
is reset, and the process moves to step S23. Step S23
Then, it is determined whether the volume value VT of the electronic volume 31T in the transmission path is the upper limit value ■TMAx. If the upper limit has not been reached, the process moves to step S24 and the volume value VT is set by 1.
Then, the process moves to step S25. Also, electronic volume 3
If the volume value VT of 1T is the upper limit ■TMAX,
The process directly advances to step S25. That is, the attenuation amount of the transmission path is gradually lowered. In step S25, the volume value VR of the electronic volume 31R of the transmission path is set to the lower limit value VRMI.
If the lower limit has not been reached, the process moves to step 326, where 1 is subtracted from the volume value VR, and the process returns to step S1. Also, the volume value V of the electronic volume 31R
If R is the lower limit value vRMIN, proceed directly to step S1.
Return to That is, the amount of attenuation in the receiving path is gradually increased. With this control, it is possible to gradually shift the no-signal mode to the transmission priority mode. The speed of transition to the transmission priority mode can be adjusted by the value of the time constant TAI.
第５図（Ｃ）は受信信号Ｔが送信信号Ｒより信号レベル
が高い時の送信優先モードの場合の処理を示すフローチ
ャートである。ステップＳ３１では、送信モードにおけ
る送信、及び受信信号の減衰量の変化率、即ち電子ボリ
ウムへの制御値出力の変化率を規定する時定数ＴＡ２と
タイマＴＡとを比較し、タイマＴＡ＞時定数ＴＡ２の時
にはステップ３３２に移り、タイマＴＡ≦時定数ＴＡ２
の時にはステップＳ１に戻る。ステップＳ３２ではタイ
マＴＡをリセットし、ステップ３３３に移る。ステップ
Ｓ３３では、送信路の電子ボリウム３１Ｔのボリウム値
ＶＴが上限値”ＴＷＡＸかどうか判断し、上限に達して
いなければ、ステップＳ３４に移ってボリウム値ＶＴに
１加算し、ステップＳ３５に移る。また、電子ボリウム
３１Ｔのボリウム値ＶＴが上限値■ＴＭＡＸ であれば
、そのままステップＳ３５に移る。即ち、送信路の減衰
量を徐々に下げていく。ステップＳ３５では、送信路の
電子ボリウム３１Ｒのボリウム値ＶＲが下限値ｖＲＭＩ
Ｎかどうか判断し、下限に達していなければ、ステップ
Ｓ３６に移ってボリウム値ＶＲから１減算し、ステップ
Ｓｌに戻る。また、電子ボリウム３１Ｒのボリウム値Ｖ
Ｒが下限値Ｖ ＲＭＩＮであれば、そのままステップＳ
１に戻る。即ち、受信路の減衰量を徐々に上げていく。FIG. 5(C) is a flowchart showing processing in the transmission priority mode when the received signal T has a higher signal level than the transmitted signal R. In step S31, timer TA is compared with time constant TA2, which defines the rate of change in attenuation of the transmission and reception signals in the transmission mode, that is, the rate of change in control value output to the electronic volume, and timer TA>time constant TA2. When , the process moves to step 332, and timer TA≦time constant TA2.
When , the process returns to step S1. In step S32, the timer TA is reset, and the process moves to step 333. In step S33, it is determined whether the volume value VT of the electronic volume 31T on the transmission path is the upper limit value "TWAX". If the upper limit has not been reached, the process moves to step S34, where 1 is added to the volume value VT, and the process moves to step S35. , if the volume value VT of the electronic volume 31T is the upper limit value ■TMAX, the process moves directly to step S35.In other words, the attenuation amount of the transmission path is gradually lowered.In step S35, the volume value of the electronic volume 31R of the transmission path is VR is lower limit vRMI
If the lower limit has not been reached, the process moves to step S36, where 1 is subtracted from the volume value VR, and the process returns to step Sl. Also, the volume value V of the electronic volume 31R
If R is the lower limit value V RMIN, proceed directly to step S.
Return to 1. That is, the amount of attenuation in the receiving path is gradually increased.
この制御により、送話信号レベルが大きい場合において
徐々に送話優先モードに移すことができる。この、送話
優先モードへの移行速度は、時定数ＴＡ２の値により調
整できる。With this control, it is possible to gradually shift to the transmission priority mode when the transmission signal level is high. The speed of transition to the transmission priority mode can be adjusted by the value of the time constant TA2.
第５図（Ｄ）は受信信号Ｔが送信信号Ｒより信号レベル
が低い時の受信優先モードの場合の処理を示すフローチ
ャートである。ステップ３４１では、送信モードにおけ
る送信、及び受信信号の減衰量の変化率、即ち電子ボリ
ウムへの制御値出力の変化率を規定する時定数ＴＡ３と
タイマＴＡとを比較し、タイマＴＡ＞時定数ＴＡ３の時
にはステップＳ４２に移り、タイマＴＡ≦時定数ＴＡ３
の時にはステップＳ１に戻る。ステップＳ４２ではタイ
マＴＡをリセットし、ステップＳ４３に移る。ステップ
３４３では、送信路の電子ボリウム３１Ｔのボリウム値
ＶＴが下限値ｖＴＭＸＮかどうか判断し、下限に達して
いなければ、ステップＳ４４に移ってボリウム値ＶＴか
ら１減算し、ステップＳ４５に移る。また、電子ボリウ
ム３１Ｔのボリウム値ＶＴが下限値ｖＴＭＸＮであれば
、そのままステップＳ４５に移る。即ち、送信路の減衰
量を徐々に上げていく。ステップＳ４５では、送信路の
電子ボリウム３１Ｒのボリウム値ＶＲが上限値ｖＲＭＡ
Ｘかどうか判断し、上限に達していなければ、ステップ
Ｓ４６に移ってボリウム値ＶＲを１加算し、ステップＳ
１に戻る。また、電子ボリウム３１Ｒのボリウム値ＶＲ
が上限値■ＲＭＡ工であれば、そのままステップＳ１に
戻る。即ち、受信路の減衰量を徐々に下げていく。この
制御により、受信信号レベルが大きい場合において徐々
に受話優先モードに移すことができる。この、受話優先
モードへの移行速度は、時定数ＴＡ３の値により調整で
きる。FIG. 5(D) is a flowchart showing the processing in the reception priority mode when the signal level of the received signal T is lower than that of the transmitted signal R. In step 341, timer TA is compared with time constant TA3, which defines the rate of change in attenuation of the transmission and reception signals in the transmission mode, that is, the rate of change in control value output to the electronic volume, and timer TA>time constant TA3. When , the process moves to step S42, and timer TA≦time constant TA3.
When , the process returns to step S1. In step S42, the timer TA is reset, and the process moves to step S43. In step 343, it is determined whether the volume value VT of the electronic volume 31T on the transmission path is the lower limit value vTMXN. If it has not reached the lower limit, the process moves to step S44, where 1 is subtracted from the volume value VT, and the process moves to step S45. Further, if the volume value VT of the electronic volume 31T is the lower limit value vTMXN, the process directly moves to step S45. That is, the attenuation amount of the transmission path is gradually increased. In step S45, the volume value VR of the electronic volume 31R of the transmission path reaches the upper limit value vRMA.
If the upper limit has not been reached, the process moves to step S46, where the volume value VR is incremented by 1, and the process proceeds to step S46.
Return to 1. In addition, the volume value VR of the electronic volume 31R
If it is the upper limit value ■RMA, the process returns to step S1. That is, the amount of attenuation in the receiving path is gradually lowered. With this control, when the received signal level is high, it is possible to gradually shift to the receive priority mode. The speed of transition to the receive priority mode can be adjusted by the value of the time constant TA3.
そして、本実施例では、ＴＡＩ＞ＴＡ２．ＴＡｌ＞ＴＡ
３とすることにより、無信号モードにおける送話優先モ
ードへの移行速度、即ち送信路および受信路の減衰量の
変化速度を、送信信号と受信信号のレベル差による送話
優先、受話優先モード間の移行速度、即ち減衰量の送信
路および受信路の減衰量の変化速度より遅（して、違和
感をなくしている。In this embodiment, TAI>TA2. TAL>TA
3, the speed of transition from the no-signal mode to the transmitting priority mode, that is, the rate of change in the attenuation of the transmitting path and the receiving path, can be adjusted between the transmitting priority mode and the receiving priority mode depending on the level difference between the transmitting signal and the receiving signal. The speed of transition of the attenuation is slower than the speed of change of the attenuation of the transmitting path and the receiving path, thereby eliminating the sense of discomfort.
以上述べたように本発明によれば、ハンズフリー電話の
ハウリングを防止するために、非優先側の信号を減衰さ
せる送話および受話の各優先モードを設定可能なハウリ
ングキャンセラ方式において、送受話共に無信号の状態
が続いたときは直前のモードと関係なく送話優先モード
に移行させるようにしたので、周囲の雑音等で不要なモ
ード切替えが生ずることを防止できる。As described above, according to the present invention, in order to prevent howling in hands-free telephones, in a howling canceller method that can set priority modes for transmitting and receiving that attenuates signals on the non-priority side, both transmitting and receiving When the no-signal condition continues, the mode is shifted to the transmission priority mode regardless of the previous mode, so unnecessary mode switching can be prevented from occurring due to ambient noise or the like.
第１図は本発明の基本構成図、 第２図はその動作説明図、 第３図は本発明の実施例の構成図、 第４図はその動作説明図、 第５図は本発明の動作を示すフローチャートである。 出 願 人 富士通テン株式会社 代理人弁理士 青 柳 稔 第５図（Ｄ） （Ｂ） ｆｉ： ｉ回 FIG. 1 is a basic configuration diagram of the present invention, Figure 2 is an explanatory diagram of its operation. FIG. 3 is a configuration diagram of an embodiment of the present invention, Figure 4 is an explanatory diagram of its operation. FIG. 5 is a flowchart showing the operation of the present invention. Sender: Fujitsu Ten Ltd. Representative Patent Attorney Minoru Ao Yanagi Figure 5 (D) (B) fi: i times
Claims (1)
また受話信号（Ｒ）をスピーカ（２）で受話音に変換す
るハンズフリー電話のハウリングキャンセラ方式におい
て、該受話信号（Ｒ）を減衰させる送話優先モードと、
該送話信号（Ｔ）を減衰させる受話優先モードとを設定
できる電子ボリウム（３１）およびコンピュータ（３２
）を備え、送受話共に無信号状態が続いたときは送話優
先モードとすることを特徴とするハンズフリー電話のハ
ウリングキャンセラ方式。 ２、無信号状態による受話優先モードから送話優先モー
ドへの切替え時は、音声信号入力によるモード切替え時
より減衰量の変化を緩やかにする請求項１記載のハンズ
フリー電話のハウリングキャンセラ方式。 ３、無信号状態による受信優先モードから送話優先モー
ドへの切替は、無信号状態が所定時間継続した時に行わ
れる請求項１又は請求項２記載のハンズフリー電話のハ
ウリングキャンセラ方式。[Claims] 1. Converting the transmitted voice into a transmitted signal (T) using the microphone (1),
Furthermore, in a howling canceller method of a hands-free telephone that converts a received signal (R) into a received sound by a speaker (2), a transmitting priority mode that attenuates the received signal (R);
An electronic volume (31) and a computer (32) that can set a receive priority mode that attenuates the transmit signal (T).
), and when there is a continuous no-signal condition for both transmitting and receiving calls, the hands-free telephone howling canceller system is characterized in that the transmitting priority mode is set. 2. The howling canceller method for a hands-free telephone according to claim 1, wherein when switching from the receiving priority mode to the sending priority mode due to a no signal state, the change in attenuation amount is made more gradual than when switching the mode due to audio signal input. 3. The howling canceller method for a hands-free telephone according to claim 1 or claim 2, wherein the switching from the reception priority mode to the transmission priority mode due to a no-signal state is performed when the no-signal state continues for a predetermined period of time.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8009488A JPH01253353A (en) | 1988-03-31 | 1988-03-31 | Howling canceler system for hand-free telephone |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8009488A JPH01253353A (en) | 1988-03-31 | 1988-03-31 | Howling canceler system for hand-free telephone |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH01253353A true JPH01253353A (en) | 1989-10-09 |
Family
ID=13708607
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8009488A Pending JPH01253353A (en) | 1988-03-31 | 1988-03-31 | Howling canceler system for hand-free telephone |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH01253353A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5414763A (en) * | 1991-04-09 | 1995-05-09 | Canon Kabushiki Kaisha | Apparatus and method for providing echo suppression to a plurality of telephones |
| US5757905A (en) * | 1994-12-07 | 1998-05-26 | Nec Corporation | Telephone set with circuit for suppression of howling and echo |
| SG82584A1 (en) * | 1997-08-06 | 2001-08-21 | Calsonic Corp | Telephone hand-free apparatus |
| JP2005303931A (en) * | 2004-04-15 | 2005-10-27 | Aiphone Co Ltd | Hands-free interphone device |
| JP2008054253A (en) * | 2006-08-28 | 2008-03-06 | Matsushita Electric Works Ltd | Interphone system for multiple dwelling house |
| JP2008054252A (en) * | 2006-08-28 | 2008-03-06 | Matsushita Electric Works Ltd | Interphone system for multiple dwelling house |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5551381A (en) * | 1978-10-12 | 1980-04-15 | Nippon Telegr & Teleph Corp <Ntt> | Buried position measuring device for underground cable |
| JPS55147864A (en) * | 1979-05-07 | 1980-11-18 | Nec Corp | Change-over controlling circuit of speaker telephone set |
| JPS57148452A (en) * | 1981-03-11 | 1982-09-13 | Yuniden Kk | Control system for transmitting and receiving line of hand-free telephone set |
| JPS61195054A (en) * | 1985-02-25 | 1986-08-29 | Matsushita Electric Works Ltd | Voice switching circuit for loudspeaking telephone set |
-
1988
- 1988-03-31 JP JP8009488A patent/JPH01253353A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5551381A (en) * | 1978-10-12 | 1980-04-15 | Nippon Telegr & Teleph Corp <Ntt> | Buried position measuring device for underground cable |
| JPS55147864A (en) * | 1979-05-07 | 1980-11-18 | Nec Corp | Change-over controlling circuit of speaker telephone set |
| JPS57148452A (en) * | 1981-03-11 | 1982-09-13 | Yuniden Kk | Control system for transmitting and receiving line of hand-free telephone set |
| JPS61195054A (en) * | 1985-02-25 | 1986-08-29 | Matsushita Electric Works Ltd | Voice switching circuit for loudspeaking telephone set |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5414763A (en) * | 1991-04-09 | 1995-05-09 | Canon Kabushiki Kaisha | Apparatus and method for providing echo suppression to a plurality of telephones |
| US5757905A (en) * | 1994-12-07 | 1998-05-26 | Nec Corporation | Telephone set with circuit for suppression of howling and echo |
| SG82584A1 (en) * | 1997-08-06 | 2001-08-21 | Calsonic Corp | Telephone hand-free apparatus |
| JP2005303931A (en) * | 2004-04-15 | 2005-10-27 | Aiphone Co Ltd | Hands-free interphone device |
| JP2008054253A (en) * | 2006-08-28 | 2008-03-06 | Matsushita Electric Works Ltd | Interphone system for multiple dwelling house |
| JP2008054252A (en) * | 2006-08-28 | 2008-03-06 | Matsushita Electric Works Ltd | Interphone system for multiple dwelling house |
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