JPS6178237A - Pull-in system - Google Patents

Pull-in system

Info

Publication number
JPS6178237A
JPS6178237A JP59201021A JP20102184A JPS6178237A JP S6178237 A JPS6178237 A JP S6178237A JP 59201021 A JP59201021 A JP 59201021A JP 20102184 A JP20102184 A JP 20102184A JP S6178237 A JPS6178237 A JP S6178237A
Authority
JP
Japan
Prior art keywords
transmission
pulse
signal
training
circuit
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.)
Granted
Application number
JP59201021A
Other languages
Japanese (ja)
Other versions
JPH0416978B2 (en
Inventor
Setsu Fukuda
福田 節
Toshitaka Tsuda
俊隆 津田
Kazuo Murano
和雄 村野
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fujitsu Ltd
Original Assignee
Fujitsu Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Fujitsu Ltd filed Critical Fujitsu Ltd
Priority to JP59201021A priority Critical patent/JPS6178237A/en
Priority to CA000491023A priority patent/CA1246174A/en
Priority to US06/779,639 priority patent/US4679188A/en
Priority to KR1019850007099A priority patent/KR900003238B1/en
Priority to EP19850112194 priority patent/EP0176098B1/en
Priority to DE8585112194T priority patent/DE3582383D1/en
Publication of JPS6178237A publication Critical patent/JPS6178237A/en
Publication of JPH0416978B2 publication Critical patent/JPH0416978B2/ja
Granted legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00Arrangements affording multiple use of the transmission path
    • H04L5/14Two-way operation using the same type of signal, i.e. duplex
    • H04L5/1423Two-way operation using the same type of signal, i.e. duplex for simultaneous baseband signals
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00Arrangements affording multiple use of the transmission path
    • H04L5/14Two-way operation using the same type of signal, i.e. duplex
    • H04L5/1469Two-way operation using the same type of signal, i.e. duplex using time-sharing
    • H04L5/1484Two-way operation using the same type of signal, i.e. duplex using time-sharing operating bytewise
    • H04L5/1492Two-way operation using the same type of signal, i.e. duplex using time-sharing operating bytewise with time compression, e.g. operating according to the ping-pong technique

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Bidirectional Digital Transmission (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)

Abstract

PURPOSE:To prevent disturbance from a transmission/reception signal at pulling in timing regenerating circuit and at pulling in echo canceller by avoiding the transmission of a transmission signal during the training pulse reception period and during twice the delay time of transmission signal from an opposite side. CONSTITUTION:The transmission operation of master side is attained as follows; A frame pulse from a frame pulse generator 1, a training pulse from a training pulse generator 2 and a transmission data are selected by a selector 3 by the control of a control circuit 6 during one frame period T and a time interval at which no signal is transmitted such as a time Tr twice the transmission delay time between a master and a slave set and a training pulse reception period Tt in succession with the said period is provided, the signal is converted into a bipolar signal by a V/B converting circuit 4, transmitted to a 2-wire transmission line via a hybrid circuit 5 and transmitted to the slave side. The locking by the echo canceller 7 is executed by the control of the control circuit 6 at the transmission of the training pulse.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、4ノービス(、θ合ディジタルAk1 (l
 S nN)に使用する、2線1(伝送路を用いでYイ
7シタル双方向伝送を実現する為の]l−″1−−1−
ヤンセフー型:1’ 4 、メタル加入者線伝送装置の
にI−キャンeラー及び夕・イミング再/V回路の引き
込めカf(の改良に関する。
[Detailed Description of the Invention] [Industrial Application Field] The present invention provides four novice (, θ combined digital Ak1 (l
2-wire 1 (to realize bidirectional transmission using a transmission line) l-''1--1- used for S nN)
Yansefu type: 1' 4 , Concerning the improvement of the I-canceller and evening/timing re/V circuit pull-in function of metal subscriber line transmission equipment.

l−配装7fにt;いては、タイミング出71回にとの
引き込、7J、I冒1F送(、−’+ (ij 5jの
ニー1−に31す々J]古今受(1ず父上、:l −−
1−ヤンL!7−の引き13め時(,1受1.;、11
1号(こよiIl姑古を受+JないこLか望:r 、4
qる。
l-In the arrangement 7f, the timing is 71 times and the pull-in, 7J, I attack 1F sending (,-'+ (ij 5j's knee 1- to 31 Suzu J) Kokinuke (1st Father, :l --
1-Yan L! At the 13th time of the draw of 7- (, 1 hit 1.;, 11
No. 1 (Koyo IIl Magu wo Uke + J Naiko Lka Nozomi: r, 4
qru.

(従来の技f+iと発明か解決し7ようと4る問題11
弓従東の)配装;6°に打いて(J、タイミンク山)1
回路の引き込ツノは送178(iコ1υのイjる1す1
間ごもfi)’、; = ) Cいる為、4綿をQ綿に
変換4−るハ(t7”II 1回路(ハ2線線路側との
インピーダンス不整6ζこ、jイ、」χ1.)(4号の
1二1−に、Iす々l)害を受i+ 、 又コ−1=1
4〕・セラーの引き込みり、l受信化−Jのイ1ン、1
すl Ijl−でもj1ノ、騙っている鳥骨(八(戸1
5月こより好古を受(Jる問題1:、1、かある。
(Conventional technique f + i and invention or problem 11 to solve 7
Bowman East) Arrangement; Hit at 6° (J, Taiming Mountain) 1
The lead-in point of the circuit is 178
Intermediate fi)', ; = ) Since C, convert 4 cotton to Q cotton 4-ru C (t7"II 1 circuit (C 2 Impedance mismatch with the line side 6ζ, j I, "χ1. ) (in No. 4 121-, I su l) harmed i+, also co-1=1
4] ・Attraction of sellers, l reception - J's In, 1
Sl Ijl-But j1ノ, the bird bone that is lying (8 (door 1)
Since May, I have received a good old book.

〔問題点を解決するための手段〕[Means for solving problems]

上記問題点は、伝送信号はフレーム構成をとり、マスタ
ー側よりの伝送信号はフレームパルス、トレーニングパ
ルス、送信データの順とし、スレーブ側よりの伝送信号
はマスター側よりのフレームパルスにより同期をとった
後、フレームパルス。
The above problem is that the transmission signal has a frame structure, the transmission signal from the master side is a frame pulse, training pulse, and transmission data in that order, and the transmission signal from the slave side is synchronized with the frame pulse from the master side. After that, frame pulse.

送信データ、トレーニングパルスの順とし、11つマス
ター側スレーブ側共、トレーニングパルス受信期間及び
マスター、スレーブ間の伝達遅延時間の2倍の711間
は伝送信号を送信しなくし、トレーニングパルス送信時
エコーキャンセラーの引き込みを行い、トレーニングパ
ルス受(a時タイミング再生引き込みを行うようにした
本発明の引き込み方式により解決される。
Transmission data and training pulses are sent in this order, and transmission signals are not transmitted on both the master and slave sides during the training pulse reception period and 711, which is twice the transmission delay time between the master and slave, and an echo canceller is used when transmitting training pulses. This problem is solved by the pull-in method of the present invention, which performs the pull-in at the time of training pulse reception (timing regeneration pull-in at time a).

〔作用〕[Effect]

本発明によれば、トレーニングパルス送信時エコーキャ
ンセラーの引き込みを行い、トレーニングパルス受信時
タイミング再生回路の引き込みを行うが、トレーニング
パルス受信期間及び相手側よりの伝送信号遅延時間の2
倍の聞伝送信号を送信しなくし、又スレーブ側はマスタ
ー側よりのフレーl、パルスを受信し同期をとった後払
■信号を送信しているので、エコーキャンセラー引き込
み時は受信信号は無く又タイミング再生回路用き込み時
は送信信号は無いので、これ等による妨害を受けずに、
夫々引き込みを行うことが出来る。
According to the present invention, the echo canceller is pulled in when the training pulse is transmitted, and the timing regeneration circuit is pulled in when the training pulse is received.
Since the slave side does not send double transmission signals, and the slave side receives the frame and pulse from the master side and transmits the synchronized deferred payment ■ signal, there is no reception signal when the echo canceller is engaged. There is no transmission signal when the timing regeneration circuit is used, so there is no interference from such things.
It is possible to draw in each.

〔実施例〕〔Example〕

第1図は本発明の実施例のブロック図で、(A)はマス
ター側(n)はスレーブ側を示し、第2図は第1図の各
部の波形のタイム九−I・で(A)はマスター側の送信
信号、(B)はマスター側の受信信号、(C)はスレー
ブ側の送信信号、(D)はスレーブ側の受信信号を示す
Fig. 1 is a block diagram of an embodiment of the present invention, (A) shows the master side (n) shows the slave side, and Fig. 2 shows the waveforms of each part in Fig. 1 at time 9-I. shows a transmitted signal on the master side, (B) shows a received signal on the master side, (C) shows a transmitted signal on the slave side, and (D) shows a received signal on the slave side.

図中1 、 14はフレームパルス発生器、2.15は
トレーニングパルス発生器、3,16はセレクタ、4,
17はユニポーラ・バイポーラ変換器(以下U/B変換
回路と称す)、5.18はバイブリド回路、6.9.2
1は制御回路、7.19はエコーキャンセラー、8,2
0は同月回路、10.22はタイミング再生回路、I+
、23は0゜1を識別する識別回路、12.24は線路
歪を補償する等化器、13.25はエコーキャンセラー
よりの擬似エコーでエコーを打ち消す為の減算回路を示
す。
In the figure, 1 and 14 are frame pulse generators, 2.15 is a training pulse generator, 3 and 16 are selectors, 4,
17 is a unipolar/bipolar converter (hereinafter referred to as U/B conversion circuit), 5.18 is a bibride circuit, 6.9.2
1 is a control circuit, 7.19 is an echo canceller, 8, 2
0 is the same month circuit, 10.22 is the timing regeneration circuit, I+
, 23 is an identification circuit for identifying 0°1, 12.24 is an equalizer for compensating line distortion, and 13.25 is a subtraction circuit for canceling the echo with a pseudo echo from an echo canceller.

第1図(A)及び第2図(A)を用いマスター側の送信
動作より説明すると、lフレーム期間T内にて、制御回
路6の制御により、第2図(A)に示すごとく、フレー
ムパルス発生器lよりのフレームパルス及びトレーニン
グパルス発生!2よりのトレーニングパルス及び送信デ
ータをセレクタ3にて選択し、且つマスター、スレーブ
間の伝達遅延時間の2倍の時間T、及びこの期間につづ
< 1−レーニングパルス受信期間T、の、何も送信し
ない時間間隔を設け、U/B変換回路4にてバイポーラ
信号に変換し、バイブリド回路5を経て2線式伝送路に
送出され、スレーブ側に送信される。
To explain the transmission operation on the master side using FIG. 1(A) and FIG. 2(A), within one frame period T, a frame is transmitted as shown in FIG. 2(A) under the control of the control circuit 6. Frame pulse and training pulse generation from pulse generator l! The training pulse and transmission data from 2 are selected by the selector 3, and a time T that is twice the transmission delay time between the master and the slave, and following this period < 1 - training pulse reception period T, nothing is A time interval is provided during which no transmission is performed, and the signal is converted into a bipolar signal by the U/B conversion circuit 4, sent out to the two-wire transmission line via the bibride circuit 5, and transmitted to the slave side.

この時フレームパルス、トレーニングパルス。At this time frame pulse, training pulse.

送信データはバイブリド回路5と2線式伝送路とのイン
ピーダンスの不整合により所謂エコーが第2図(B)の
斜線で示す如く受信側に廻り込む。
Due to the impedance mismatch between the vibrid circuit 5 and the two-wire transmission line, so-called echoes of the transmitted data go around to the receiving side as shown by diagonal lines in FIG. 2(B).

そこで、エコーキャンセラー7の引き込みは第2図(A
)のトレーニングパルスCを送信した時制?11回!/
36の制illにより行う。
Therefore, the pull-in of the echo canceller 7 is shown in Figure 2 (A
) in which tense was the training pulse C sent? 11 times! /
It is done by the control of 36.

マスター側よりスレーブ側に送られて来た第2図(A>
に示す信号はマスター、スレーブ間の伝達遅延時間遅れ
て、第1図(B)のハイブリ1回路18を介して第2図
(D)に示す如く受信され、減算回路251等化器24
.識別回路23を経て出力され、この出力より同期回路
20にてフレームパルスによりフレーム同期をとり、制
ffj回路21にて第21m (r))のaに示すトレ
ーニングパルスによりタイミング再生回路22の引き込
みを行いタイミングを再41−シ又制御回路21の制f
ilにより、1フレ一ム期間内にて第2図(C)に示す
如くフレームパルス発生器14よりのフレームパルス及
び送信データ及びトレーニングパルス発生器15よりの
トレーニングパルスをセレクタI6にて選IJ? L、
目、つマスター、スレーブ間の伝達遅延時間の2倍及び
)・レーニングバルス受fε期間の何も送信しない時間
間隔を設け、tJ / B変換回路17にてバイポーラ
信号に変換し、バイブリド回路18を経て2線式伝送路
に送出されマスター側に送(古される。
Figure 2 (A>) sent from the master side to the slave side
The signal shown in is received as shown in FIG. 2(D) via the hybrid 1 circuit 18 in FIG.
.. It is outputted via the identification circuit 23, and from this output, the synchronization circuit 20 performs frame synchronization using a frame pulse, and the control ffj circuit 21 uses the training pulse shown in 21m(r)) a to pull in the timing regeneration circuit 22. The control circuit 21 also controls the control circuit 21.
il, the frame pulse and transmission data from the frame pulse generator 14 and the training pulse from the training pulse generator 15 are selected by the selector I6 as shown in FIG. 2(C) within one frame period. L,
tJ/B conversion circuit 17 converts the signal into a bipolar signal, and bibride circuit 18 Then, it is sent out to the two-wire transmission line and sent (used) to the master side.

この時、フレームパルス、送信データ、トレーニングパ
ルスはバイブリド回路18と2線式伝送路とのインピー
ダンスの不整合により所謂エコーが第2図(D)の斜線
で示す如く受信側に廻り込む。
At this time, a so-called echo of the frame pulse, transmission data, and training pulse goes around to the receiving side as shown by diagonal lines in FIG. 2(D) due to impedance mismatch between the vibrid circuit 18 and the two-wire transmission line.

そこで、エコーキャンセラー19の引き込みは第2図(
C)のトレーニングパルスdを送信した時、制御回路2
1の制御により行う。
Therefore, the pull-in of the echo canceller 19 is as shown in Figure 2 (
When the training pulse d of C) is transmitted, the control circuit 2
This is done using the control in step 1.

このスレーブ側よりマスター側に送られた第2図(C)
に示す信号はスレーブ、マスター間の伝達遅延時間遅れ
て、第1図(八)のバイブリド回路5を介して第2図(
I3)に示す如く受信され、減算回路131等化器12
.識別回路11を経て出力され、この出力より同期回路
8にてフレームパルスによりフレーム同期をとり、制御
回路9にて第21図(B)のbに示すトレーニングパル
スによりタイミング再生回路10の引き込みを11い、
タイミング再律を行う。
Figure 2 (C) sent from this slave side to the master side
The signal shown in FIG. 2 is transmitted through the vibrid circuit 5 shown in FIG. 1 (8) after a transmission delay time between the slave and the master.
I3) is received as shown in FIG.
.. It is outputted through the identification circuit 11, and from this output, the synchronization circuit 8 performs frame synchronization using a frame pulse, and the control circuit 9 uses the training pulse shown in FIG. stomach,
Perform timing re-templation.

このように、スレーブ側ではマスター側のフレームパル
スを受信し同1すIをとった後送信信号を送信し又マス
ター側スレーブ側ノLマスター、ス1/−ブ間の伝達遅
延時間の2倍及びトレーニングパルス受信朋間は何も送
信しないので、タイミング再生回路10.22の引き込
め時は送イ、AI、い月Ill :I!!口、X1:+
 −−1−ヤンセラ−7,19の引き込め時Ll受信(
5号は;l!!!いので、ごね等の影響を受けずに引き
込みを行うことが出来る。
In this way, the slave side receives the frame pulse from the master side, takes the same value, and then transmits the transmission signal, and the transmission delay time between the master side and the slave side is twice the transmission delay time between the master and slave side. Since nothing is transmitted during the training pulse reception period, when the timing regeneration circuit 10.22 is retracted, it is sent, AI, Ill: I! ! Mouth, X1:+
--1-Yansera-7, 19 Ll reception when retracting (
No. 5 is ;l! ! ! Therefore, retraction can be performed without being affected by squeezing or the like.

尚マスター側においては、スレーブ側からのトレーニン
グパルスたりてなく、送(八がJAilさね、受13デ
ータが到来している期間中のパルスを検出して、タイミ
ング再生用のパルスとしく利用″4る事が出来、又スレ
ーブ側においても、マスター側が送信したフレームパル
スを検出し′ζタイミング再4L用のパルスとして利用
する事も出来る。
In addition, the master side does not receive training pulses from the slave side, but detects pulses during the period when data is being received, and uses them as pulses for timing reproduction. Furthermore, on the slave side, it is also possible to detect the frame pulse transmitted by the master side and use it as a pulse for re-timing 4L.

C発明の効果〕 以1−詳細に説明lる如く本発明によれば、タイミング
再生回路の引き込み時は送信信号は無く、又エコーキャ
ンセラーの引き込み時は受信信号は無いので、これ等の
影響を受けずに引き込みを行うことが出来る効果がある
C. Effects of the Invention] As described in 1-Detailed Description, according to the present invention, there is no transmitting signal when the timing regeneration circuit is engaged, and there is no receiving signal when the echo canceller is engaged, so the effects of these effects can be avoided. It has the effect of being able to pull in without receiving it.

【図面の簡単な説明】[Brief explanation of the drawing]

第1図は本発明の実施例のブロック図、第2図は第1図
の各部の波形のタイムチ、−トである。 図において、 1.14はフレームパルス発生器、 2.15はトレーニングパルス発生28.3.16はセ
レクタ、 4.17はユニポーラ・バイポーラ変換器、5.18は
バイブリド回路、 6.9.21は制御回路、 7.19はエコーキャンセラー、 8.20は同期回路、 10.22はタイミング再生回路、 11.23は識別回路、 12.24は等花器、
FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a time chart of waveforms at various parts in FIG. 1. In the figure, 1.14 is a frame pulse generator, 2.15 is a training pulse generator, 28.3.16 is a selector, 4.17 is a unipolar-bipolar converter, 5.18 is a bibrid circuit, and 6.9.21 is a Control circuit, 7.19 is an echo canceller, 8.20 is a synchronization circuit, 10.22 is a timing regeneration circuit, 11.23 is an identification circuit, 12.24 is a flower vase,

Claims (1)

【特許請求の範囲】[Claims] 2線式伝送路を用いてディジタル双方向伝送を実現する
為の、エコーキャンセラー型ディジタル加入者線伝送装
置において、伝送信号はフレーム構成をとり、マスター
側よりの伝送信号はフレームパルス、トレーニングパル
ス、送信データの順とし、スレーブ側よりの伝送信号は
、マスター側よりのフレームパルスにより同期をとつた
後、フレームパルス、送信データ、トレーニングパルス
の順とし、且つマスター側スレーブ側共、トレーニング
パルス受信期間及びマスター、スレーブ間の伝送遅延時
間の2倍の期間は伝送信号を送信停止し、トレーニング
パルス送信時エコーキャンセラーの引き込みを行い、ト
レーニングパルス受信時タイミング再生引き込みを行う
ようにしたことを特徴とする引き込み方式。
In an echo canceller type digital subscriber line transmission device for realizing digital two-way transmission using a two-wire transmission line, the transmission signal has a frame structure, and the transmission signal from the master side consists of frame pulses, training pulses, The transmission signal from the slave side is synchronized with the frame pulse from the master side, and then the frame pulse, transmission data, and training pulse in this order, and both the master and slave sides have a training pulse reception period. Also, transmission of the transmission signal is stopped during a period twice the transmission delay time between the master and slave, the echo canceller is pulled in when the training pulse is transmitted, and the timing regeneration pull-in is performed when the training pulse is received. Retraction method.
JP59201021A 1984-09-26 1984-09-26 Pull-in system Granted JPS6178237A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
JP59201021A JPS6178237A (en) 1984-09-26 1984-09-26 Pull-in system
CA000491023A CA1246174A (en) 1984-09-26 1985-09-18 Digital transmission system
US06/779,639 US4679188A (en) 1984-09-26 1985-09-24 Digital transmission system
KR1019850007099A KR900003238B1 (en) 1984-09-26 1985-09-26 Digital transmission system
EP19850112194 EP0176098B1 (en) 1984-09-26 1985-09-26 Digital transmission system
DE8585112194T DE3582383D1 (en) 1984-09-26 1985-09-26 DIGITAL TRANSMISSION SYSTEM.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP59201021A JPS6178237A (en) 1984-09-26 1984-09-26 Pull-in system

Publications (2)

Publication Number Publication Date
JPS6178237A true JPS6178237A (en) 1986-04-21
JPH0416978B2 JPH0416978B2 (en) 1992-03-25

Family

ID=16434145

Family Applications (1)

Application Number Title Priority Date Filing Date
JP59201021A Granted JPS6178237A (en) 1984-09-26 1984-09-26 Pull-in system

Country Status (1)

Country Link
JP (1) JPS6178237A (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE112004001455B4 (en) * 2003-08-07 2020-04-23 Intersil Americas LLC Cross-talk cancellation method and system

Also Published As

Publication number Publication date
JPH0416978B2 (en) 1992-03-25

Similar Documents

Publication Publication Date Title
DE2740123C2 (en) Echo cancellation arrangement for a digital data transmission system
RU2535918C2 (en) Underwater communication system
CN105611324B (en) Simulate high-resolution video transfer system
ES8202640A1 (en) Method and device for examination by means of ultrasonic beams
JPS6178237A (en) Pull-in system
JPH039655B2 (en)
NL8102225A (en) DEVICE FOR COMPENSATING ECO SIGNALS.
FR2412986A1 (en) DIGITAL SIGNAL TRANSMISSION SYSTEM
DE3752233D1 (en) Data terminal for transmission over an analog two-way line with echo cancellation coupled to the receive clock
WO1992004794A3 (en) Alarm and test system for a digital main line
CN114584717B (en) Audio interaction method and device
RU2099884C1 (en) Method of duplex transmission of digital information over two-wire circuit and device for its realization
JPS62271528A (en) Subscriber line transmission equipment
SE8207517L (en) ACTIVATION OF TRANSMISSION LINK THROUGH CODE TRANSMISSION
JPH01826A (en) echo canceller device
JPS61157039A (en) Subscriber line transmitter
ATE83347T1 (en) METHOD AND CIRCUIT ARRANGEMENT FOR SYNCHRONIZING A CLOCK GENERATOR.
JPS61199338A (en) Echo canceller training system
JPS6325732B2 (en)
NO153829C (en) PROCEDURE FOR PREPARING RELATIONS FROM PARTICIPATION STATIONS RESP. TRANSFER CABLES ASSOCIATED WITH A DATA PROCESSING SYSTEM FOR SIGNAL CONVERTERS.
JPH02109436A (en) Synchronizing pull-in circuit
JPS60241127A (en) Transmission method of video signal to color printer
EP0480322A3 (en)
JPS63226137A (en) Digital signal transmission system
JPH01278178A (en) Video camera system and camera head and camera control unit used in the same