JPS63237624A - Time-division multiplexer - Google Patents
Time-division multiplexerInfo
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- JPS63237624A JPS63237624A JP7124887A JP7124887A JPS63237624A JP S63237624 A JPS63237624 A JP S63237624A JP 7124887 A JP7124887 A JP 7124887A JP 7124887 A JP7124887 A JP 7124887A JP S63237624 A JPS63237624 A JP S63237624A
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Abstract
Description
【発明の詳細な説明】
〔概 要」
本発明は、マルチメディアの時分割多重化装置において
、人力信号である音声信号及びＧＩＩＩファクシミリ信
号等のモデム信号の信号識別を行い、その結果、モデム
信号の場合のみその信号速度に袋も近い伝送速度で送出
するようにしたものである。[Detailed Description of the Invention] [Summary] The present invention performs signal identification of modem signals such as voice signals and GIII facsimile signals, which are human signals, in a multimedia time division multiplexing device. Only in this case, the signal is transmitted at a transmission speed that is close to the signal speed.
本発明は、時分割多重化装置に関し、特に入力信号の種
類に応じた伝送速度のディジクル信号を送出する時分割
多重化装置に関するものである。The present invention relates to a time division multiplexing device, and more particularly to a time division multiplexing device that sends digital signals at a transmission rate depending on the type of input signal.
音声信号及びファクシミリ信号等の干チ゛ｌ、・ε通遇
するアナログ信号（以下、モデム信号と言う）を符号化
するンステムの一例が第４図に示されており、電話Ｒ５
及びＧＩ［Ｉ規格のファクシミリ６（モデムを内蔵して
おり出力はアナログ信号となっている）が交換機３に接
続されており、交１ＡＪａ７から送出されるアナログ信
号は、符号化部８で３２ ＫｂｐｓＡＤＰＣＭ方式の符
号化が行われ出力される。An example of a system for encoding commonly used analog signals (hereinafter referred to as modem signals) such as voice signals and facsimile signals is shown in FIG.
and GI [I standard facsimile 6 (with a built-in modem and output is an analog signal) are connected to the exchange 3, and the analog signal sent from the AC 1AJa 7 is converted into 32 Kbps ADPCM by the encoder 8. The method is encoded and output.
この３２ ＫｂｐｓＡＤＰＣＭ方式の符号化部８として
は、ＣＣＩＴＴ勧告のものがあり、ＮＴＴ網とか他社網
との接続を考えると、このＣＣＩＴＴ勧告に従ったもの
を使用した方がよいことは当然である。The encoding section 8 of this 32 Kbps ADPCM system is based on the CCITT recommendation, and when considering connections with NTT networks and other companies' networks, it is natural that it is better to use one that complies with this CCITT recommendation.
しかしながら、ＣＧＩＴＴ勧告Ｇ、７２１に準拠した３
２ ＫｂｐｓＡＤＰ側方式の符号他方式の予測器は、音
声品質の面から音声フォルマント特性を意識した伝達関
数を持つものであり、ＣＣＩＴＴ勧告ｖ、２９に準拠し
たモデム信号（９，６にｂｐｓ）の疎通に関しては４，
８Ｋｂｐｓ （、、か保証されない。However, 3 in accordance with CGITT Recommendation G, 721
The predictor of the 2 Kbps ADP side system has a transfer function that takes into account the voice formant characteristics from the perspective of voice quality, and is based on modem signals (9 and 6 bps) that comply with CCITT Recommendation v.29. Regarding communication, 4.
8Kbps (,, or not guaranteed.
一方、最近のファクシミリは殆どＧ■規格のものが使用
されており、このＧ［［［規格のファクシミリは９．６
Ｋｂｐｓの伝送速度を使用するので、ＣＣＩＴＴ肋告Ｇ
、７２１準拠の符号化部はそのままではファクシミリ用
には使用できない。On the other hand, most recent facsimile machines are of the G■ standard, and the G[[[standard facsimile is 9.6
Since it uses a transmission rate of Kbps, the CCITT charge G
, 721-compliant encoder cannot be used as is for facsimile purposes.
従って、符号化部としては、音声信号の場合はＣＣＩＴ
Ｔ勧告に合致し、ファクシミリ信号の如くモデムからの
信号の場合は９．６Ｋｂｐｓを疎通できる時分割多重化
装置が望まれている。Therefore, in the case of an audio signal, the encoding section uses CCIT.
There is a need for a time division multiplexing device that complies with the T Recommendation and can communicate signals from a modem, such as facsimile signals, at 9.6 Kbps.
第５図は特開昭６１−２０８３１９号公報に示されてい
る本出願人による符号化方式を示すもので、そこでは、
入力部にファクシミリよりモデムに対して送信要求があ
ると、相手側のモデムが同期引き込みをするために送信
するＣＣＩＴＴ勧告ν、２９に準拠したモデムのトレー
ニングパルスを検出する信号識別回路としてのトレーニ
ングパルス検出器１０でトレーニングパルスが検出され
れば、スイッチＳＷ１及びＳＷ２を点線側に切り替えて
予ＩＩＩ器１２を使用するようにする。このときはモデ
ムから出力される１、７ＫＨｚのキャリアをキャリア監
視部１３で監視しており、モデムの使用を止めキャリア
が無くなるとキャリア監視部１３はスイッチＳ Ｗ １
及びＳＷ２を実線側に切り替える。FIG. 5 shows the encoding method proposed by the present applicant as disclosed in Japanese Patent Application Laid-Open No. 61-208319, in which:
When the facsimile sends a transmission request to the modem at the input section, the modem at the other end sends a training pulse for synchronization, which is a training pulse as a signal identification circuit that detects the training pulse of the modem that complies with CCITT Recommendation ν, 29. When the training pulse is detected by the detector 10, the switches SW1 and SW2 are switched to the dotted line side so that the pre-III device 12 is used. At this time, the carrier monitoring unit 13 monitors the 1.7 KHz carrier output from the modem, and when the modem is stopped and the carrier runs out, the carrier monitoring unit 13 switches the switch SW1.
and switch SW2 to the solid line side.
スイッチＳＷ２又はキャリア監視部１３からの音声信号
又はファクシミリ信号はアナログ／ディジクル変換器１
４で６４ Ｋｂｐｓの伝送速度のディジタル信号に変換
され、減算器１５で予測器１１又は１２からの出力信号
との差分がとられ、量子化器１６で量子化されて３２に
ｂｐｓの伝送速度で出力される。The voice signal or facsimile signal from the switch SW2 or the carrier monitoring section 13 is sent to the analog/digital converter 1.
4, it is converted into a digital signal with a transmission rate of 64 Kbps, a subtracter 15 takes the difference with the output signal from the predictor 11 or 12, and a quantizer 16 quantizes the signal, and the signal is converted into a digital signal with a transmission rate of 32 kbps. Output.
量子化器１６の出力は逆量子化器１７にも入力されて逆
量子化され、予測器１１又は１２で予測係数が乗ぜられ
減算器１５へ送られる。The output of the quantizer 16 is also input to the inverse quantizer 17 where it is inversely quantized, multiplied by a prediction coefficient in the predictor 11 or 12, and sent to the subtracter 15.
この場合、予測器ｉｉはＣＣＩＴＴ勧告Ｇ、７２１に準
拠した音声フォルマント特性の伝達関数を有し、予測器
１２はファクシミリからのＣＣＩＴＴ勧告ｖ、２９に準
拠した９、６にｂｐｓのモデム信号を疎通できるように
するためにＣＣＩＴＴ勧告Ｇ、７２１に準拠せずに全周
波数帯域に渡って特徴付けない伝達関数を有するもので
ある。In this case, predictor ii has a transfer function of voice formant characteristics that complies with CCITT Recommendation G, 721, and predictor 12 communicates a modem signal of 9,6 bps that complies with CCITT Recommendation V, 29 from a facsimile. In order to be able to do so, it does not comply with CCITT Recommendation G.721 and has an uncharacterized transfer function over the entire frequency band.
上記の従来例では、入力信号を識別しモデム信号と音声
信号とでそれぞれ異なる予測器に切り替えるようにして
おり、音声信号の品質劣化はなく、またモデム信号の疎
通も可能となるが、周波数スペクトラムが平均化された
モデム信号も帯域圧縮（６４Ｋｂｐｓ→３２Ｋｂｐｓ）
を行っているため、タンデム接続した場合の中継リンク
数は能力的（エラーレート的）に１〜２リンクが限界で
ある。In the conventional example above, the input signal is identified and the predictors are switched to different predictors for the modem signal and the voice signal, so there is no deterioration in the quality of the voice signal and it is possible to communicate the modem signal, but the frequency spectrum The averaged modem signal is also bandwidth compressed (64Kbps → 32Kbps)
Therefore, the number of relay links in the case of tandem connection is limited to 1 to 2 links in terms of capacity (in terms of error rate).
また、ＧＩＩＩファクシミリの伝送速度は９．６ Ｋｂ
ｐｓであるが、変調されて音声帯域アナログ信号で送出
されるため、ディジクルネットワークで（受用される場
合は、３２Ｋｂｐｓを専有してしまうという問題点があ
った。Also, the transmission speed of GIII facsimile is 9.6 Kb.
PS, but because it is modulated and sent as a voice band analog signal, there is a problem in that it occupies 32 Kbps (if it is accepted by digital networks).
従って、本発明の目的は、中継リンク数を増やしてもモ
デム信号の品質劣化がなく且つ効率的にディジタル回線
を専有できる時分割多重化装置を実現することにある。SUMMARY OF THE INVENTION Therefore, an object of the present invention is to realize a time division multiplexing apparatus that can efficiently monopolize a digital line without deteriorating the quality of modem signals even when the number of relay links is increased.
第１図は上記の目的を達成するための本発明に係る時分
割多重化装置の概念図を示したもので、１はモデム信号
と音声信号とを識別する信号識別回路、２はモデム信号
を識別したとき該モデム信号を復調してその伝送速度に
最も近い伝送速度で該モデム信号を送出するモデム信号
送出回路２、そして、３は音声信号を識別したとき該音
声信号の音声帯域を圧縮して送出する音声圧縮回路３と
、を含んでいる。FIG. 1 shows a conceptual diagram of a time division multiplexing device according to the present invention for achieving the above object, in which 1 is a signal identification circuit that identifies modem signals and voice signals; A modem signal sending circuit 2 demodulates the modem signal when it is identified and sends the modem signal at a transmission speed closest to the transmission speed; and 3 compresses the audio band of the audio signal when it identifies the audio signal. and an audio compression circuit 3 for transmitting the audio data.
第１図に示す時分割多重化装置では、人力信号がファク
シミリ信号等のモデム信号か又は音声信号かを信号識別
回路１で識別し、モデム信号の場合は、モデム信号送出
回路２において復調した上、モデム信号の速度に最も近
い伝送速度で伝送路に送出するとともに、音声信号の場
合は音声圧縮回路３で音声帯域を圧縮して伝送路に送出
する。従って、モデム信号の場合には帯域圧縮は受けず
、また、音声信号の帯域全体に渡って専有するようなこ
とがない。In the time division multiplexing device shown in FIG. 1, a signal identification circuit 1 identifies whether a human signal is a modem signal such as a facsimile signal or a voice signal, and if it is a modem signal, it is demodulated in a modem signal transmission circuit 2 and then , the signal is sent to the transmission path at a transmission speed closest to the speed of the modem signal, and in the case of an audio signal, the audio band is compressed by the audio compression circuit 3 and sent to the transmission path. Therefore, in the case of a modem signal, the band is not compressed, and the entire audio signal band is not monopolized.
以下、本願発明に係る時分割多重化装置の実施例を説明
する。Embodiments of the time division multiplexing apparatus according to the present invention will be described below.
第２図は、第１図に概念的に示した本発明の時分割多重
化装置の一実施例を示しており、この時分割多重化装置
１０において第１図に示した信号識別回路１は、ＣＣＩ
ＴＴ勧告ｖ、２９に準拠したトレーニングパルスを検出
した時、ＧＩＩＩファクシミリ信号と認識するものであ
り、モデム信号送出回路２は、モデム信号を復調するＣ
ＣＩＴＴ勧告ｖ、２９に！＃拠した復調器２１と、この
復調器２１の信号レベルを変（＾するインタフェース変
換回路２２と、このインタフェース変換回路２２の出力
をモデム信号゛速度に最も近い伝送速度に変換する速度
変換回路２３と、で構成されている。FIG. 2 shows an embodiment of the time division multiplexing device of the present invention conceptually shown in FIG. 1. In this time division multiplexing device 10, the signal identification circuit 1 shown in FIG. , C.C.I.
When a training pulse conforming to TT Recommendation v.29 is detected, it is recognized as a GIII facsimile signal, and the modem signal transmission circuit 2 uses a C to demodulate the modem signal.
CITT Recommendation v, 29! a demodulator 21 based on the modem signal, an interface conversion circuit 22 that changes the signal level of this demodulator 21, and a speed conversion circuit 23 that converts the output of this interface conversion circuit 22 to a transmission speed closest to the modem signal speed. It consists of and.
この時分割多重化装置１０では、マルチメディアの時分
割多重化を行うため、（ＩＪファクシミリＦ及び電話機
Ｔに回線接続されたＰＢＸからの信号に対して各々、信
号識別回路１と、モデム信号送出回路２と、音声圧縮回
路３とを一組としてそれぞれ対向する時分割多重化装置
（図示せず）と接続されるようになっている。In order to perform time division multiplexing of multimedia, this time division multiplexing device 10 uses a signal identification circuit 1 and a modem signal transmission circuit for signals from a PBX connected to an IJ facsimile F and a telephone T, respectively. The circuit 2 and the audio compression circuit 3 are connected as a pair to opposing time division multiplexing devices (not shown).
更に、信号識別回路１からの識別信号は時分割多重（Ｔ
ＤＭ）バス制御回路１１に送られ、モデム信号送出回路
２及び音声圧縮回路３から７０Ｍバス１２への信号を制
御している。Furthermore, the identification signal from the signal identification circuit 1 is subjected to time division multiplexing (T
DM) is sent to the bus control circuit 11 and controls signals from the modem signal sending circuit 2 and audio compression circuit 3 to the 70M bus 12.
次に、この実施例の動作を説明すると、まず、ファクシ
ミリＦ又は電話ＩａＴからＰＢＸを介して 。Next, the operation of this embodiment will be explained.First, from the facsimile F or the telephone IaT via the PBX.
時分割多重化装置１０の信号識別回路１に入力された音
声帯アナログ信号（０，３〜３．４ＫＨｚ）が、ＣＣＩ
ＴＴ勧告ｖ、２９のモデムトレーニングパルス検出の場
合、信号識別回路１はその入力信号をＧｌファクシミリ
信号と認識してモデム信号送出回路２内のｖ、２９の復
調器２１に送出する。モデムトレーニングパルスを検出
しない場合は、信号識別回路１は入力信号を音声信号と
認識して音声圧縮回路３に送出する。The audio band analog signal (0.3 to 3.4 KHz) input to the signal identification circuit 1 of the time division multiplexer 10 is
In the case of modem training pulse detection according to TT Recommendation v.29, the signal identification circuit 1 recognizes the input signal as a Gl facsimile signal and sends it to the demodulator 21 of v.29 in the modem signal transmission circuit 2. If a modem training pulse is not detected, the signal identification circuit 1 recognizes the input signal as a voice signal and sends it to the voice compression circuit 3.
一方、信号識別回路ｌでの識別結果はそれぞれＴＤＭバ
ス制御回路１１に通知される。On the other hand, the identification results of the signal identification circuit 1 are notified to the TDM bus control circuit 11, respectively.
復調器２１に入力されたファクシミリ・アナログ信号は
ＣＣＩＴＴ勧告ν、２４／ν、２８のディジタル信号（
９，６Ｘｂｐｓ）に復調され、更にインタフェース変換
回路２２によりＴＴＬ信号レベルに変換される。そして
、このレベル変換された９、６ Ｋｂｐｓのディジタル
信号は速度変換回路２３により１６Ｋｂｐｓに変換され
、第３図に示すように７０ＭバスＩ２の６４にｂｐｓ（
８ビツト・８Ｋ［Ｉｚ）ｅＪＩ域中の１６にｂｐ！ｉ（
２ビツト・８Ｋ Ｈｚ） ？ｉＪｌ域に収容する。The facsimile analog signal input to the demodulator 21 is a digital signal (
9.6Xbps), and further converted to a TTL signal level by the interface conversion circuit 22. Then, this level-converted digital signal of 9.6 Kbps is converted to 16 Kbps by the speed conversion circuit 23, and as shown in FIG.
8 bit/8K [Iz) 16 bp in the eJI range! i(
2 bit/8K Hz)? It will be accommodated in the iJl area.
信号識別回路１への人力信号が音声信号であったときは
、音声圧縮回路３において３２Ｋｂｐｓ又は１６Ｋｂｐ
ｓに圧縮され、７０Ｍバス１２の６４にｂｐｓ領域中の
３２Ｋｂｐｓ（４ビット：第３図参照）の領域に収容す
る。When the human input signal to the signal identification circuit 1 is an audio signal, the audio compression circuit 3 outputs 32Kbps or 16Kbps.
The data is compressed to 32 Kbps (4 bits: see FIG. 3) in the 64 bps area of the 70 M bus 12.
信号識別回路１での識別結果を既に受けているＴＤＭバ
ス制御回路１１は、７０Ｍバス１２に人力される信号速
度に応じたバス領域を確保するとともに対向光の装置の
時分割多重化装置（図示せず）にも通知する。The TDM bus control circuit 11, which has already received the identification result from the signal identification circuit 1, secures a bus area corresponding to the signal speed manually input to the 70M bus 12, and also controls the time division multiplexing device (Fig. (not shown) will also be notified.
このようにして、端末からのアナログ信号を時分割多重
化して適当な伝送速度で対向する装置に送る。In this way, analog signals from the terminal are time-division multiplexed and sent to the opposing device at an appropriate transmission rate.
［発明の効果〕
以上のように、本発明の時分割多重化装置によれば、モ
デム信号と音声信号とを識別してモデム信号のみ帯域圧
縮をかけずに復調してその信号速度に最も近い伝送速度
を有するように速度変換しているので、タンデム接続し
ても帯域圧縮による信号の劣化がなく、また音声信号帯
域全体を専有するというようなことがなく、回線を有効
に使用できるという効果がある。[Effects of the Invention] As described above, according to the time division multiplexing device of the present invention, a modem signal and an audio signal are identified, only the modem signal is demodulated without band compression, and the signal speed closest to that of the modem signal is demodulated. Since the speed is converted to match the transmission speed, there is no signal deterioration due to band compression even when connected in tandem, and the entire audio signal band is not monopolized, making it possible to use the line effectively. There is.
第１図は本発明に係る時分割多重化装置の原理ブロック
図、
第２図は本発明による時分割多重化装置の一実施例を示
すブロック図、
第３図は本発明の時分割多重化装置でのＴＤＭバスの専
有状態を示す図、
第４図は音声信号及びファクシミリ信号を符号化する一
般的なシステムの一例を示すブロック図、第５図は従来
の３２ＫｂｐｓＡＤＰｃＭ方式の符号化部の構成を示す
ブロック図、である。
第１図及び第２図において、
１は信号識別回路、
２はモデム信号送出回路、
３は音声圧縮回路、
２１は復調器、
２２はインタフェース変換回路、
２３は速度変換回路、
尚、図中、同一符号は同−又は相当部分を示す。
特 許出願人 富 士 通 株式会社代理人弁理士
森 １）寛 （外１名）本発明のＢ存分側条■Ｖヒ宗
ｊＷの原王里図第１図
（’Ｋｂρｓ） （ｔ６に） （１６Ｋ）ＴＤｉΔ
バスの春情４大蒐図
第３図FIG. 1 is a principle block diagram of a time division multiplexing device according to the present invention, FIG. 2 is a block diagram showing an embodiment of a time division multiplexing device according to the present invention, and FIG. 3 is a time division multiplexing device according to the present invention. FIG. 4 is a block diagram showing an example of a general system for encoding voice signals and facsimile signals; FIG. 5 is a diagram showing the configuration of a conventional 32 Kbps ADPcM encoding unit. FIG. 1 and 2, 1 is a signal identification circuit, 2 is a modem signal sending circuit, 3 is an audio compression circuit, 21 is a demodulator, 22 is an interface conversion circuit, and 23 is a speed conversion circuit. The same reference numerals indicate the same or equivalent parts. Patent applicant Fujitsu Co., Ltd. Agent Patent Attorney
Mori 1) Hiroshi (1 other person) B full side strip of the present invention ■ V Hisou jW's Hara Ohri map Figure 1 ('Kbρs) (at t6) (16K) TDiΔ
Bus no Shunjo 4 major collections Figure 3
Claims (3)
（１）と、 前記モデム信号を識別したとき該モデム信号を復調して
その伝送速度に最も近い伝送速度で該モデム信号を送出
するモデム信号送出回路（２）と、前記音声信号を識別
したとき該音声信号の音声帯域を圧縮して送出する音声
圧縮回路（３）と、を含むことを特徴とする時分割多重
化装置。(1) A signal identification circuit (1) that identifies a modem signal and an audio signal; and a modem that, when identifying the modem signal, demodulates the modem signal and sends out the modem signal at a transmission speed closest to that transmission speed. A time division multiplexing device comprising: a signal transmission circuit (2); and an audio compression circuit (3) that compresses and transmits the audio band of the audio signal when the audio signal is identified.
２９に準拠したトレーニングパルスを検出した時、ＧI
IIファクシミリ信号と認識するものである特許請求の範
囲第１項に記載の時分割多重化装置。(2) The signal identification circuit (1) conforms to CCITT Recommendation V.
When a training pulse compliant with 29 is detected, the GI
2. The time division multiplexing device according to claim 1, which recognizes a facsimile signal.
号を復調するＣＣＩＴＴ勧告Ｖ．２９に準拠した復調器
（２１）と、該復調器（２１）の信号レベルを変換する
インタフェース変換回路（２２）と、該インタフェース
変換回路（２３）の出力をモデム信号速度に最も近い伝
送速度に変換する速度変換回路（２３）と、で構成され
ている特許請求の範囲第２項に記載の時分割多重化装置
。(3) The modem signal sending circuit (2) demodulates the modem signal according to CCITT Recommendation V. A demodulator (21) that is compliant with 29, an interface conversion circuit (22) that converts the signal level of the demodulator (21), and an interface conversion circuit (23) that converts the output of the interface conversion circuit (23) to the transmission speed closest to the modem signal speed. The time division multiplexing device according to claim 2, comprising a speed conversion circuit (23) for converting the speed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62071248A JP2584447B2 (en) | 1987-03-25 | 1987-03-25 | Time division multiplexer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62071248A JP2584447B2 (en) | 1987-03-25 | 1987-03-25 | Time division multiplexer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63237624A true JPS63237624A (en) | 1988-10-04 |
| JP2584447B2 JP2584447B2 (en) | 1997-02-26 |
Family
ID=13455208
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62071248A Expired - Fee Related JP2584447B2 (en) | 1987-03-25 | 1987-03-25 | Time division multiplexer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2584447B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03121665A (en) * | 1989-03-02 | 1991-05-23 | Eci Telecom Ltd | Communication system |
| US6188978B1 (en) | 1998-01-13 | 2001-02-13 | Nec Corporation | Voice encoding/decoding apparatus coping with modem signal |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62230130A (en) * | 1986-03-31 | 1987-10-08 | Toshiba Corp | Time division multiplex transmission system |
| JPS6326044A (en) * | 1986-07-18 | 1988-02-03 | Nec Corp | Voice coding device |
-
1987
- 1987-03-25 JP JP62071248A patent/JP2584447B2/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62230130A (en) * | 1986-03-31 | 1987-10-08 | Toshiba Corp | Time division multiplex transmission system |
| JPS6326044A (en) * | 1986-07-18 | 1988-02-03 | Nec Corp | Voice coding device |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03121665A (en) * | 1989-03-02 | 1991-05-23 | Eci Telecom Ltd | Communication system |
| EP0529104A2 (en) * | 1989-03-02 | 1993-03-03 | Eci Telecom Ltd. | Telecommunication system |
| EP0529104B1 (en) * | 1989-03-02 | 1995-07-19 | Eci Telecom Ltd. | Telecommunication system |
| US6188978B1 (en) | 1998-01-13 | 2001-02-13 | Nec Corporation | Voice encoding/decoding apparatus coping with modem signal |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2584447B2 (en) | 1997-02-26 |
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