JP3512518B2 - Echo canceller - Google Patents
Echo cancellerInfo
- Publication number
- JP3512518B2 JP3512518B2 JP10467795A JP10467795A JP3512518B2 JP 3512518 B2 JP3512518 B2 JP 3512518B2 JP 10467795 A JP10467795 A JP 10467795A JP 10467795 A JP10467795 A JP 10467795A JP 3512518 B2 JP3512518 B2 JP 3512518B2
- Authority
- JP
- Japan
- Prior art keywords
- signal
- echo
- reference signal
- output
- eco
- 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 - Fee Related
Links
Landscapes
- Filters That Use Time-Delay Elements (AREA)
- Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
Description
【発明の詳細な説明】
【０００１】
【産業上の利用分野】本発明は電話回線を介して相手局
から戻ってくるエコ−を打ち消すエコ−キャンセラに関
するものである。
【０００２】
【従来技術】長距離電話回線では、相手側の電話装置を
通して自分の声が遅延されて戻って来るため、エコ−と
なって通話に著しい障害を与えることがある。これを防
ぐための装置がエコ−キャンセラであり、電話装置の主
装置の送受信回路等に設置される。図３は従来のエコ−
キャンセラの構成を示すブロック図である。図示するよ
うに、従来のエコ−キャンセラはＦＩＲフィルタ（非巡
回形フィルタ）３０、係数更新部３４、加算器３５を具
備する。ＦＩＲフィルタ（非巡回形フィルタ）３０は複
数個の遅延素子３１−１、３１−２、・・・、アンプ３
２−１、３２−２、・・・加算器３３を有し、係数更新
部３４でＦＩＲフィルタ３０の係数（ゲイン）を設定す
るように構成されている。
【０００３】ＦＩＲフィルタ３０の各遅延素子３１−
１、３１−２、・・・は遅延時間が設定されて送信信号
線３６から直列に接続され、各接続点からはアンプ３２
−１、３２−２、・・・が接続され、各アンプの出力は
加算器３３の入力に接続されている。更に、加算器３３
の出力は受信信号線３７と共に加算器３５の入力に接続
される。加算器３５の出力は係数更新部３４の入力に接
続され、係数更新部３４の出力は各アンプのゲインを調
整するように接続されている。
【０００４】送信信号は送信信号線３６から局へ送信さ
れると共に、各遅延素子３１−１、３１−２、・・・を
通して各アンプに入力され、各アンプの出力信号は加算
器３３で加算され疑似エコ−信号ｓを発生させる。受信
信号線３７で受信した受信信号は加算器３５で疑似エコ
−信号ｓが減算された後、受信処理されると共に、係数
更新部３４へ入力される。係数更新部３４はＣＰＵ（中
央処理装置）を具備し、受信信号に含まれるエコ−信号
が最小になるように各アンプのゲインを調整し、加算器
３３は最適な疑似エコ−信号ｓを出力する。受信信号に
含まれるエコ−信号は電話回線により異なり、係数更新
部３４は電話回線毎に繰返し学習することにより疑似エ
コ−信号ｓの最適化を図っている。
【０００５】
【発明が解決しようとする課題】しかしながら、上記に
述べた従来のエコ−キャンセラはエコ−時間（送信信号
のエコ−が戻って来るまでの時間）が長い場合、ＦＩＲ
フィルタ（非巡回型フィルタ）３０の遅延素子及びアン
プの数を増加する必要があり、各アンプの係数（ゲイ
ン）を最適化する処理が膨大な量となり係数更新部３４
で処理ができなくなると云う問題があった。
【０００６】本発明は上述の点に鑑みてなされたもの
で、上記問題点を除去し、エコ−時間の長短に関わらず
キャンセル処理量が一定になるエコ−キャンセラを提供
することを目的とする。
【０００７】
【課題を解決するための手段】上記課題を解決するため
本発明は、電話機に設けられ、相手局からの音声信号に
含まれるエコー信号を打ち消すエコーキャンセラであっ
て、自局から送信される音声信号を常時サンプリング
し、サイクリックに順次時系列に格納する音声データ格
納手段（１２）と、相手局へ送信する音声信号の特定の
周波数成分を抽出し搬送波として使用し周期的に発生す
る基準信号を送出する基準信号送出手段（２）と、該送
出する基準信号と相手局から戻って来る基準信号の振幅
を比較し振幅比を求める振幅比較手段（５）と、該送出
する基準信号と相手局から戻って来る基準信号の遅延時
間を求める位相比較手段（１０）と、該遅延時間から音
声データ格納手段（１２）の所定のデータ位置を求め該
データを振幅比に合わせて調整し、疑似エコーＳを出力
する疑似エコー出力手段（エコー量推定器１１とアンプ
１３）と、相手局から受信した音声信号から該疑似エコ
ーＳを減算し、該受信した音声信号に含まれるエコーを
打ち消す手段（１４）を設けたことを特徴とする。
【０００８】
【作用】本発明では、上記に説明したように、基準信号
の送信時と受信時の振幅比と、基準信号の送信から受信
までの遅延時間によりエコ−を推定し、格納している音
声信号のデ−タから疑似エコ−Ｓを算出し、受信した音
声信号から減算するので、疑似エコー出力手段の処理量
はエコ−時間の長短に関係なく一定となる。従って、従
来のようにハ−ドウエア素子を増やすことなく、エコ−
時間の長短に関係なく安定した通話が期待できる。ま
た、基準信号を送る搬送波は送信信号から抽出するので
雑音等の障害も少なくなる。
【０００９】
【実施例】以下、本発明の一実施例を図面に基づいて詳
細に説明する。図１は本発明のエコ−キャンセラの構成
を示すブロック図である。図示するように本発明のエコ
−キャンセラはバンドパスフィルタ１、基準信号発生器
２、変調器３、加算器４、レベル比較部５、微分器６、
バンドパスフィルタ７、検波器８、微分器９、位相比較
器１０、エコ−量推定器１１、リングバッファ１２、ア
ンプ１３、加算器１４を具備する。
【００１０】送信信号線１５はバンドパスフィルタ１の
入力及び、加算器４の一方の入力に接続され、バンドパ
スフィルタ１の出力は基準信号発生器（方形波発生器）
２の出力と共に変調器３の入力に接続され、変調器３の
出力は加算器４の一方の入力に接続され、加算器４の出
力は出力線１６に接続されている。
【００１１】受信信号線１７は加算器１４の入力に接続
すると共にバンドパスフィルタ７を通して検波器８に接
続する。検波器８の出力及び基準信号発生器２の出力は
レベル比較器５の入力に接続されると共に、それぞれ微
分器９及び微分器６を通して位相比較器１０の入力に接
続される。
【００１２】レベル比較器５の出力及び、位相比較器１
０の出力はエコ−量推定器１１の入力に接続され、その
出力はリングバッファ１２及びアンプ１３のゲイン調整
端子に接続される。送信信号線１５はリングバッファ１
２の入力に接続され、リングバッファ１２の出力はアン
プ１３の入力に接続され、アンプ１３の出力は受信信号
線１７と共に加算器１４の入力に接続され、該加算器１
４の出力は入力線１８に接続されている。
【００１３】リングバッファ１２は送信信号Ｔ（音声信
号）を１２５μｓのサンプリング周期で常時サンプリン
グし、２５０ｍｓ分のデ−タ（振幅）をサイクリックに
順次時系列で格納する記憶装置である。
【００１４】次に動作を説明する。送信信号Ｔ（音声信
号）はバンドパスフィルタ１で２．４ＫＨｚ±５０Ｈｚ
の信号が抽出され、その出力信号は変調器３で基準信号
発生器２の出力信号（２５０ｍｓ周期の方形波）で変調
（振幅変調）され、変調器３の出力信号は送信信号Ｔと
加算器４で加算され出力線１６から出力される。
【００１５】受信信号Ｒは受信信号線１７で受信され、
バンドパスフィルタ７を通して２．４ＫＨｚ±５０Ｈｚ
の信号が抽出されて検波器８で基準信号が復調され、信
号振幅が基準信号発生器２の出力信号（２５０ｍｓ周期
の方形波）とレベル比較器５で比較され、基準信号の送
信時と受信時の振幅比が出力される。更に、検波器８で
復調された信号は微分器９で微分され、基準信号発生器
２の出力信号は微分器６で微分され、共に立上り部分を
抽出し位相比較器１０で位相が比較され、基準信号の送
信から受信までの遅延時間がエコ−量推定器１１へ出力
される。
【００１６】エコ−量推定器１１はレベル比較器５の出
力信号（振幅比）及び、位相比較器１０の出力信号（遅
延時間）からエコ−量を推定し、疑似エコ−信号を発生
させる（詳細後述）。即ち、リングバッファ１２に格納
されたデ−タ（時系列で格納されるデ−タ）から所定の
デ−タを取り出す位置を指定し、前記デ−タを増幅する
アンプ１３のゲインを指示する。アンプ１３はエコ−量
推定器１１の指示に従ってゲインを設定し前記デ−タに
応じた信号（疑似エコ−信号Ｓ）を加算器１４へ出力す
る。加算器１４は受信信号Ｒから疑似エコ−信号Ｓを減
算し入力線１８へ出力する。
【００１７】図２はエコ−量推定器の動作を示すフロ−
チャ−トである。エコ−量推定器１１はＣＰＵ及びメモ
リ（図では省略）を具備し、本フロ−チャ−トを実行す
るプログラムはエコ−量推定器１１のメモリに格納され
ＣＰＵで実行される。図２のフロ−チャ−トに従って説
明する。エコ−量推定器１１はレベル比較器５及び位相
比較器１０の出力信号を読み込む（ステップＳＴ１）。
【００１８】位相比較器１０の出力信号を基にリングバ
ッファ１２の取り出し位置を決める（ステップＳＴ
２）。レベル比較器５の出力信号を基にアンプ１３のゲ
インを決定する（ステップＳＴ３）。リングバッファ１
２へデ−タの出力（アンプ１３への出力）を指示し（ス
テップＳＴ４）、アンプ１３へゲインの設定を指示し、
デ−タを疑似エコ−信号Ｓとして出力させる（ステップ
ＳＴ５）。以上のステップＳＴ１〜ステップＳＴ５を繰
返し実行する。
【００１９】上記説明は発呼側のエコ−キャンセンラで
あり、バンドパスフィルタ１は送信信号Ｔ（音声信号）
中で知覚にあまり影響しない２．４ＫＨｚ±５０Ｈｚの
狭帯域の信号を抽出し基準信号（２５０ｍｓ周期の方形
波）で変調をかけて利用した。また、着呼側のエコ−キ
ャンセンラの周波数帯域は発呼側との混信を防ぐために
２．６ＫＨｚ±５０Ｈｚを使用すればよい。上記基準信
号を乗せる周波数及び周波数帯域、基準信号の周期（２
５０ｍｓ）とそれに関連したリングバッファサイズ（２
５０ｍｓの格納分）は一例として使用した値であって、
他の値を使用してもよい。
【００２０】上記説明したように本実施例によれば、基
準信号の送信時と受信時の振幅比と基準信号の送信から
受信までの遅延時間によりエコ−量を推定し、格納して
いる音声信号のデ−タから疑似エコ−信号Ｓを算出し受
信信号Ｒから減算するので、エコ−時間に関係なくエコ
−量推定器１１の処理量は一定となり、電話回線による
エコ−時間の長短に関係なく安定した通話が期待でき
る。また、基準信号を送る搬送波は送信信号から抽出す
るので雑音等の障害も少なくなる。
【００２１】
【発明の効果】以上説明したように本発明によれば、下
記のような優れた効果が期待される。基準信号の送信時
と受信時の振幅比と、基準信号の送信から受信までの遅
延時間によりエコ−を推定し、格納している音声信号の
デ−タから疑似エコ−Ｓを算出し、受信した音声信号か
ら減算するので、疑似エコー出力手段の処理量はエコ−
時間の長短に関係なく一定となる。従って、従来のよう
にハ−ドウエア素子を増やすことなく、エコ−時間の長
短に関係なく安定した通話が期待できる。また、基準信
号を送る搬送波は送信信号から抽出するので雑音等の障
害も少なくなる。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eco-canceller for canceling an echo returned from a partner station via a telephone line. 2. Description of the Related Art In a long-distance telephone line, since the user's own voice is delayed and returned through a telephone device of the other party, the voice becomes ecological and may cause a serious obstacle to the call. An apparatus for preventing this is an eco-canceller, which is installed in a transmitting / receiving circuit or the like of a main apparatus of the telephone apparatus. Fig. 3 shows the conventional eco-
FIG. 3 is a block diagram illustrating a configuration of a canceller. As shown, the conventional eco-canceller includes an FIR filter (non-recursive filter) 30, a coefficient updating unit 34, and an adder 35. The FIR filter (acyclic filter) 30 includes a plurality of delay elements 31-1, 31-2,.
., 32-2,... Are provided with an adder 33, and the coefficient updating section 34 sets a coefficient (gain) of the FIR filter 30. Each delay element 31 of the FIR filter 30
, 31-2,... Are connected in series from the transmission signal line 36 with a delay time set, and the amplifier 32 is connected from each connection point.
-1, 32-2,... Are connected, and the output of each amplifier is connected to the input of the adder 33. Further, the adder 33
Is connected to the input of the adder 35 together with the reception signal line 37. The output of the adder 35 is connected to the input of the coefficient updating unit 34, and the output of the coefficient updating unit 34 is connected to adjust the gain of each amplifier. The transmission signal is transmitted from the transmission signal line 36 to the station, and is input to each amplifier through each of the delay elements 31-1, 31-2,..., And the output signal of each amplifier is added by the adder 33. To generate a pseudo echo signal s. The reception signal received by the reception signal line 37 is subjected to reception processing after the pseudo echo signal s is subtracted by the adder 35, and is input to the coefficient updating unit 34. The coefficient updating unit 34 includes a CPU (Central Processing Unit), adjusts the gain of each amplifier so that the echo signal included in the received signal is minimized, and the adder 33 outputs the optimum pseudo echo signal s. I do. The echo signal included in the received signal differs depending on the telephone line, and the coefficient updating unit 34 optimizes the pseudo echo signal s by repeatedly learning for each telephone line. [0005] However, the conventional eco-canceller described above has a problem in that when the eco-time (time until the echo of the transmission signal returns) is long, the FIR is not effective.
It is necessary to increase the number of delay elements and amplifiers of the filter (acyclic filter) 30, and the process of optimizing the coefficient (gain) of each amplifier becomes enormous, and the coefficient updating unit 34
There is a problem that processing cannot be performed. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to eliminate the above-mentioned problems and to provide an eco-canceller in which the cancellation processing amount is constant regardless of the length of the eco-time. . [0007] In order to solve the above-mentioned problems, the present invention is an echo canceller provided in a telephone set for canceling an echo signal contained in a voice signal from a partner station. Audio data storage means (12) for constantly sampling the audio signal to be received and cyclically sequentially storing the audio signal, and extracting a specific frequency component of the audio signal to be transmitted to the other station and using it as a carrier to generate periodically. Reference signal transmitting means (2) for transmitting a reference signal to be transmitted, amplitude comparing means (5) for comparing the amplitude of the transmitted reference signal with the reference signal returned from the partner station, and obtaining an amplitude ratio; Phase comparing means (10) for determining a delay time between a signal and a reference signal returned from a partner station; Is adjusted in accordance with the amplitude ratio, a pseudo echo output means (echo amount estimator 11 and amplifier 13) for outputting a pseudo echo S, and the pseudo echo S is subtracted from the audio signal received from the partner station. A means (14) for canceling an echo contained in the audio signal is provided. According to the present invention, as described above, the echo is estimated and stored based on the amplitude ratio between the transmission and reception of the reference signal and the delay time from transmission to reception of the reference signal. Since the pseudo echo S is calculated from the data of the audio signal present and subtracted from the received audio signal, the processing amount of the pseudo echo output means is constant regardless of the length of the echo time. Therefore, without increasing the number of hardware elements as in the prior art,
A stable call can be expected regardless of the length of time. In addition, since the carrier for transmitting the reference signal is extracted from the transmission signal, interference such as noise is reduced. An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the eco-canceller of the present invention. As shown, the eco-canceller of the present invention comprises a bandpass filter 1, a reference signal generator 2, a modulator 3, an adder 4, a level comparator 5, a differentiator 6,
It comprises a band pass filter 7, a detector 8, a differentiator 9, a phase comparator 10, an echo amount estimator 11, a ring buffer 12, an amplifier 13, and an adder 14. A transmission signal line 15 is connected to the input of the bandpass filter 1 and one input of the adder 4, and the output of the bandpass filter 1 is a reference signal generator (square wave generator).
The output of the adder 4 is connected to one input of the adder 4, and the output of the adder 4 is connected to the output line 16. The reception signal line 17 is connected to the input of the adder 14 and to the detector 8 through the band pass filter 7. The output of the detector 8 and the output of the reference signal generator 2 are connected to the input of a level comparator 5 and to the input of a phase comparator 10 through differentiators 9 and 6, respectively. The output of the level comparator 5 and the phase comparator 1
The output of 0 is connected to the input of the echo amount estimator 11, and its output is connected to the ring buffer 12 and the gain adjustment terminal of the amplifier 13. Transmission signal line 15 is ring buffer 1
2, the output of the ring buffer 12 is connected to the input of the amplifier 13, and the output of the amplifier 13 is connected to the input of the adder 14 together with the reception signal line 17.
The output of 4 is connected to input line 18. The ring buffer 12 is a storage device which constantly samples the transmission signal T (audio signal) at a sampling period of 125 μs and stores data (amplitude) for 250 ms cyclically and sequentially in time series. Next, the operation will be described. Transmission signal T (voice signal) is 2.4 KHz ± 50 Hz by band pass filter 1
Is extracted, and the output signal is modulated (amplitude modulated) by the modulator 3 with the output signal (square wave having a period of 250 ms) of the reference signal generator 2, and the output signal of the modulator 3 is combined with the transmission signal T and the adder. 4 and are output from the output line 16. The reception signal R is received on the reception signal line 17,
2.4KHz ± 50Hz through band pass filter 7
Is extracted and the reference signal is demodulated by the detector 8, and the signal amplitude is compared with the output signal of the reference signal generator 2 (square wave having a period of 250 ms) by the level comparator 5. The amplitude ratio at the time is output. Further, the signal demodulated by the detector 8 is differentiated by a differentiator 9, the output signal of the reference signal generator 2 is differentiated by a differentiator 6, both rising edges are extracted, and the phases are compared by a phase comparator 10. The delay time from transmission to reception of the reference signal is output to the eco-quantity estimator 11. The echo amount estimator 11 estimates the echo amount from the output signal (amplitude ratio) of the level comparator 5 and the output signal (delay time) of the phase comparator 10 and generates a pseudo echo signal ( Details will be described later). That is, a position for extracting predetermined data from data stored in the ring buffer 12 (data stored in time series) is designated, and a gain of the amplifier 13 for amplifying the data is designated. . The amplifier 13 sets the gain according to the instruction of the echo amount estimator 11 and outputs a signal (pseudo echo signal S) corresponding to the data to the adder 14. The adder 14 subtracts the pseudo echo signal S from the received signal R and outputs the result to the input line 18. FIG. 2 is a flowchart showing the operation of the eco-quantity estimator.
It is a chart. The eco-amount estimator 11 includes a CPU and a memory (not shown), and a program for executing the flowchart is stored in the memory of the eco-amount estimator 11 and executed by the CPU. This will be described with reference to the flowchart of FIG. The echo amount estimator 11 reads the output signals of the level comparator 5 and the phase comparator 10 (step ST1). The take-out position of the ring buffer 12 is determined based on the output signal of the phase comparator 10 (step ST).
2). The gain of the amplifier 13 is determined based on the output signal of the level comparator 5 (step ST3). Ring buffer 1
2 to output data (output to the amplifier 13) (step ST4), and instruct the amplifier 13 to set a gain.
The data is output as the pseudo echo signal S (step ST5). The above steps ST1 to ST5 are repeatedly executed. The above description is of an eco-canceller on the calling side, and the band-pass filter 1 transmits a transmission signal T (voice signal).
Among them, a narrow band signal of 2.4 KHz ± 50 Hz which does not significantly affect the perception was extracted and modulated with a reference signal (square wave having a period of 250 ms) for use. Further, the frequency band of the called eco-canceler may be 2.6 KHz ± 50 Hz in order to prevent interference with the calling side. The frequency and frequency band on which the reference signal is placed, and the period of the reference signal (2
50 ms) and its associated ring buffer size (2
Is a value used as an example,
Other values may be used. As described above, according to the present embodiment, the amount of echo is estimated based on the amplitude ratio between the time of transmission and reception of the reference signal and the delay time between transmission and reception of the reference signal, and the stored voice is stored. Since the pseudo echo signal S is calculated from the signal data and subtracted from the received signal R, the processing amount of the eco amount estimator 11 is constant regardless of the eco time, and the eco time by the telephone line can be reduced. Regardless, you can expect a stable call. In addition, since the carrier for transmitting the reference signal is extracted from the transmission signal, interference such as noise is reduced. As described above, according to the present invention, the following excellent effects are expected. The echo is estimated based on the amplitude ratio between the transmission and reception of the reference signal and the delay time from transmission to reception of the reference signal, and a pseudo echo-S is calculated from the data of the stored audio signal and received. Is subtracted from the converted audio signal, the processing amount of the pseudo echo output means is eco-friendly.
It is constant regardless of the length of time. Therefore, a stable telephone call can be expected regardless of the length of the eco-time without increasing the number of hardware elements as in the related art. In addition, since the carrier for transmitting the reference signal is extracted from the transmission signal, interference such as noise is reduced.
【図面の簡単な説明】
【図１】本発明のエコ−キャンセラの構成例を示すブロ
ック図である。
【図２】エコ−量推定器の動作を示すフロ−チャ−トで
ある。
【図３】従来のエコ−キャンセラの構成例を示すブロッ
ク図である。
【符号の説明】
１ バンドパスフィルタ
２ 基準信号発生器
３ 変調器
４ 加算器
５ レベル比較部
６ 微分器
７ バンドパスフィルタ
８ 検波器
９ 微分器
１０ 位相比較器
１１ エコ−量推定器
１２ リングバッファ
１３ アンプ
１４ 加算器BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration example of an eco-canceller of the present invention. FIG. 2 is a flowchart showing the operation of an eco amount estimator. FIG. 3 is a block diagram showing a configuration example of a conventional eco-canceller. [Description of Signs] 1 Band-pass filter 2 Reference signal generator 3 Modulator 4 Adder 5 Level comparator 6 Differentiator 7 Band-pass filter 8 Detector 9 Differentiator 10 Phase comparator 11 Eco-quantity estimator 12 Ring buffer 13 Amplifier 14 Adder
フロントページの続き (56)参考文献 特開 平６−21851（ＪＰ，Ａ) 特開 平４−117855（ＪＰ，Ａ) 特開 平６−311547（ＪＰ，Ａ) 特開 平４−177922（ＪＰ，Ａ) 特開 平４−355549（ＪＰ，Ａ) 特開 昭52−142906（ＪＰ，Ａ) 特開 昭63−84216（ＪＰ，Ａ) 特開 昭57−75055（ＪＰ，Ａ) 特開 平６−188849（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) H04B 1/76 H04B 3/00 H04B 7/00 H04M 1/00 Continuation of the front page (56) References JP-A-6-21851 (JP, A) JP-A-4-117855 (JP, A) JP-A-6-311547 (JP, A) JP-A-4-177922 (JP) JP-A-4-355549 (JP, A) JP-A-52-142906 (JP, A) JP-A-63-84216 (JP, A) JP-A-57-75055 (JP, A) 6-188849 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) H04B 1/76 H04B 3/00 H04B 7/00 H04M 1/00
Claims (1)
号に含まれるエコー信号を打ち消すエコーキャンセラで
あって、 自局から送信される音声信号を常時サンプリングし、サ
イクリックに順次時系列に格納する音声データ格納手段
と、前記相手局へ送信する音声信号の特定の周波数成分
を抽出し搬送波として使用し周期的に発生する基準信号
を送出する基準信号送出手段と、該送出する基準信号と
前記相手局から戻って来る基準信号の振幅を比較し振幅
比を求める振幅比較手段と、該送出する基準信号と前記
相手局から戻って来る基準信号の遅延時間を求める位相
比較手段と、該遅延時間から前記音声データ格納手段の
所定のデータ位置を求め該データを前記振幅比に合わせ
て調整し疑似エコーを出力する疑似エコー出力手段と、
前記相手局から受信した音声信号から該疑似エコーを減
算し該受信した音声信号に含まれるエコーを打ち消す手
段を設けたことを特徴とするエコーキャンセラ。(57) [Claims 1] An echo canceller provided in a telephone set for canceling an echo signal included in an audio signal from a partner station, which constantly samples an audio signal transmitted from the own station. Voice data storage means for cyclically and sequentially storing time-series data; and reference signal transmitting means for extracting a specific frequency component of a voice signal to be transmitted to the other station, using the carrier as a carrier wave, and transmitting a periodically generated reference signal. Amplitude comparing means for comparing the amplitude of the reference signal to be transmitted with the reference signal returning from the partner station to obtain an amplitude ratio; and determining the delay time between the reference signal to be transmitted and the reference signal returning from the partner station. A pseudo-echo for obtaining a predetermined data position of the audio data storage means from the delay time, adjusting the data in accordance with the amplitude ratio, and outputting a pseudo echo Output means;
An echo canceller comprising means for subtracting the pseudo echo from an audio signal received from the partner station and canceling an echo included in the received audio signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10467795A JP3512518B2 (en) | 1995-04-04 | 1995-04-04 | Echo canceller |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10467795A JP3512518B2 (en) | 1995-04-04 | 1995-04-04 | Echo canceller |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08279777A JPH08279777A (en) | 1996-10-22 |
| JP3512518B2 true JP3512518B2 (en) | 2004-03-29 |
Family
ID=14387108
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10467795A Expired - Fee Related JP3512518B2 (en) | 1995-04-04 | 1995-04-04 | Echo canceller |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3512518B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000040985A (en) * | 1998-07-22 | 2000-02-08 | Oki Electric Ind Co Ltd | Echo cancler |
| US6351531B1 (en) * | 2000-01-21 | 2002-02-26 | Motorola, Inc. | Method and system for controlling echo cancellation using zero echo path, ringing, and off-hook detection |
-
1995
- 1995-04-04 JP JP10467795A patent/JP3512518B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08279777A (en) | 1996-10-22 |
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