JPS5921138A - Transmitting system having amplitude-frequency characteristic variation compensating circuit - Google Patents
Transmitting system having amplitude-frequency characteristic variation compensating circuitInfo
- Publication number
- JPS5921138A JPS5921138A JP57130902A JP13090282A JPS5921138A JP S5921138 A JPS5921138 A JP S5921138A JP 57130902 A JP57130902 A JP 57130902A JP 13090282 A JP13090282 A JP 13090282A JP S5921138 A JPS5921138 A JP S5921138A
- Authority
- JP
- Japan
- Prior art keywords
- amplitude
- video signal
- level
- frequency characteristic
- detects
- 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
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B3/00—Line transmission systems
- H04B3/02—Details
- H04B3/04—Control of transmission; Equalising
- H04B3/10—Control of transmission; Equalising by pilot signal
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Television Systems (AREA)
- Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
Abstract
Description
【発明の詳細な説明】
本発明は振幅−周波数特性変動補償回路を有する伝送シ
ステムに関し、特にベースバンドビデオ信号を伝送する
光伝送システムに関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transmission system having an amplitude-frequency characteristic variation compensation circuit, and more particularly to an optical transmission system for transmitting baseband video signals.
第１図は従来の光伝送システムを説明する図である。第
１図（ａ）は光伝送システムの系統図、第１図（ｂ）は
光受信機のブロック図、第１図（ｃ）はベースバンドビ
デオ信号及びパイロット信号の周波数スペクトラムを示
す図である。この光伝送システムはベースバンドビデオ
信号にパイロット信号を重畳して伝送するシステムであ
り、光送信機２がベースバンドビデオ入力信号とパイロ
ット発信機１により発生された周波数ｆｐのパイロット
信号とを光ファイバー３にのせる。光受信機４は伝送さ
れた信号を受信して、第１図（ｂ）に示すようにパイロ
ット信号用帯域フィルタ５及び検波回路６からなる帰還
回路によりパイロット信号のレベル変動を検出して、ビ
デオ信号レベルが変動しないように自動利得制御（以下
、ＡＧＣという）をかけている。つまり、ＡＧＣはパイ
ロット信号のレベルを検出してその出力レベルを一定に
保とうとするので、パイロット信号レベルだけでなくベ
ースバンドビデオ信号レベルも一定に保たれる。しかし
、温度変動他の原因によって光送信機２及び／あるいは
光受信機４の振幅−周波数特性が変動した場合には、光
受信機４においてＡＧＣをかけているにも関わらずベー
スバンドビデオ出力信号の出力レベルが変動する。これ
は、振幅周波数特性が変動した場合にはＡＧＣをかける
ことによってパイロット信号の出力レベルだけが一定に
保たれるが、ベースバンドビデオ信号はレベル変動が生
じてしまうからである。つまり、従来のベースバンドビ
デオ信号伝送システムは何らかの原因で送信機及び／あ
るいは受信機の振幅−周波数特性が変動した場合にはＡ
ＧＣをかけてもベースバンド信号のレベル変動が生じる
欠点を有している。FIG. 1 is a diagram illustrating a conventional optical transmission system. FIG. 1(a) is a system diagram of an optical transmission system, FIG. 1(b) is a block diagram of an optical receiver, and FIG. 1(c) is a diagram showing frequency spectra of a baseband video signal and a pilot signal. . This optical transmission system is a system in which a pilot signal is superimposed on a baseband video signal and transmitted, and an optical transmitter 2 transmits a baseband video input signal and a pilot signal of frequency fp generated by a pilot transmitter 1 to an optical fiber 3. Put it on. The optical receiver 4 receives the transmitted signal and detects the level fluctuation of the pilot signal by a feedback circuit consisting of a pilot signal bandpass filter 5 and a detection circuit 6 as shown in FIG. 1(b). Automatic gain control (hereinafter referred to as AGC) is applied so that the signal level does not fluctuate. In other words, since the AGC detects the level of the pilot signal and tries to keep its output level constant, not only the pilot signal level but also the baseband video signal level is kept constant. However, if the amplitude-frequency characteristics of the optical transmitter 2 and/or the optical receiver 4 fluctuate due to temperature fluctuations or other causes, the baseband video output signal output level fluctuates. This is because when the amplitude frequency characteristic changes, only the output level of the pilot signal is kept constant by applying AGC, but the level of the baseband video signal changes. In other words, in conventional baseband video signal transmission systems, if the amplitude-frequency characteristics of the transmitter and/or receiver fluctuate for some reason, the
Even when GC is applied, it has the disadvantage that the baseband signal level fluctuates.
本発明の目的は、ベースバンド信号とパイロット信号と
を重畳して伝送するベースバンドビデオ信号伝送システ
ムにおける振幅−周波数特性の変動を補償する振幅−周
波数特性変動補償回路を備えた伝送システムを提供する
ことである。An object of the present invention is to provide a transmission system equipped with an amplitude-frequency characteristic variation compensation circuit that compensates for amplitude-frequency characteristic variation in a baseband video signal transmission system that superimposes and transmits a baseband signal and a pilot signal. That's true.
以下に図面を参照して本発明について詳細に説明する光
伝送システムについて説明するが、本発明は通常のベー
スバンド電気信号を伝送する伝送システムにも適用でき
る。The present invention will be described below in detail with reference to the drawings regarding an optical transmission system, but the present invention can also be applied to a transmission system that transmits ordinary baseband electrical signals.
第２図は本発明の振幅−周波数特性変動補償回路１０を
有するベースバンドビデオ信号伝送システムの実施例を
示す図である。この実施例では第１図（ｂ）の光受信機
回路に変動補償回路１０が付加されている。この変動補
償回路１０は、ベースバンドビデオ信号のピーク値を検
出するビデオピーク検波回路１１、ベースバンドビデオ
信号成分とパイロット信号成分とを比較してビデオ信号
のレベル変動分を検出する差動増幅器１２、及びヘッド
アンプ７の帰還回路に接続された可変容量ダイオード１
３とから成る。この変動補償回路１０はパイロット信号
成分に対するベースバンドビデオ信号成分のレベル変動
を可変容量ダイオード１３の容量の変化に帰還させて伝
送システムの振幅−周波数特性の変動を補償するもので
ある。FIG. 2 is a diagram showing an embodiment of a baseband video signal transmission system having the amplitude-frequency characteristic variation compensation circuit 10 of the present invention. In this embodiment, a fluctuation compensation circuit 10 is added to the optical receiver circuit shown in FIG. 1(b). The fluctuation compensation circuit 10 includes a video peak detection circuit 11 that detects the peak value of the baseband video signal, and a differential amplifier 12 that compares the baseband video signal component and the pilot signal component to detect level fluctuations of the video signal. , and a variable capacitance diode 1 connected to the feedback circuit of the head amplifier 7.
It consists of 3. This fluctuation compensation circuit 10 feeds back level fluctuations of the baseband video signal component relative to the pilot signal component to changes in the capacitance of the variable capacitance diode 13, thereby compensating for fluctuations in the amplitude-frequency characteristics of the transmission system.
第３図は本発明における振幅二周波数特性変動補償回路
の動作を説明する図である。第３図（ａ）が正常なベー
スバンドビデオ信号及びパイロット信号の周波数スペク
トラムである。今、例えば、温度上昇のために振幅−周
波数特性が第３図（ｂ）に示すように高域下降になった
とすれば、パイロット信号成分がＡＧＣにより正常なレ
ベルに保たれているので、第３図（ｃ）に示すようにベ
ースバンドビデオ信号成分は全体のレベルが上昇する。FIG. 3 is a diagram illustrating the operation of the amplitude two-frequency characteristic variation compensation circuit according to the present invention. FIG. 3(a) shows the frequency spectrum of a normal baseband video signal and pilot signal. Now, for example, if the amplitude-frequency characteristic drops in the high range due to temperature rise as shown in Figure 3(b), the pilot signal component is maintained at a normal level by AGC, so the As shown in FIG. 3(c), the overall level of the baseband video signal component increases.
ここで、変動補償回路１０が、ベースバンドビデオ信号
成分がパイロット信号成分に比べて増加したことを検出
し可変容量ダイオード１３の端子間電圧を変化させるこ
とにより、第３図（ｄ）のように振幅−周波数特性の高
域を持ち上げる。この場合にもパイロット信号成分はＡ
ＧＣにより正常なレベルに戻されるので、変動補償回路
１０はベースバンドビデオ信号とパイロット信号とのレ
ベルが正常な状態に復帰するように動作し、第３図（ｅ
）に示す正常な周波数スペクトラムが得られる。Here, the fluctuation compensation circuit 10 detects that the baseband video signal component has increased compared to the pilot signal component and changes the voltage between the terminals of the variable capacitance diode 13, as shown in FIG. 3(d). Raise the high range of the amplitude-frequency response. In this case as well, the pilot signal component is A
Since the levels of the baseband video signal and the pilot signal are returned to normal levels by the GC, the fluctuation compensation circuit 10 operates so that the levels of the baseband video signal and the pilot signal are returned to normal states, as shown in FIG.
) A normal frequency spectrum is obtained.
第４図は本発明における変動補償レベル範囲を例示する
図である。実験によれば、ベースバンドビデオ信号レベ
ルとパイロット信号レベルとの間の±１ｄＢ程度内のレ
ベル変動を変化なしに補償することができた。FIG. 4 is a diagram illustrating a variation compensation level range in the present invention. According to experiments, it was possible to compensate for level fluctuations within approximately ±1 dB between the baseband video signal level and the pilot signal level without any change.
本発明の応用分野は、ベースバンドビデオ信号伝送シス
テム特に光伝送システムがある。The field of application of the invention is baseband video signal transmission systems, in particular optical transmission systems.
第１図は従来の光伝送システムを説明する図、第２図は
本発明の振幅−周波数特性変動補償回路１０を有するデ
ータ伝送システムの実施例を示す図、第３図は本発明に
おける振幅−周波数特性変動補償回路の動作を説明する
図、第４図は本発明における変動補償レベル範囲を例示
する図である。
１：パイロット発信機 ２：光送信機
３：光ファイバー ４：光受信機
５：パイロット信号用帯域フィルタ ６：検波回路７：
ヘッドアンプ １０：変動補償回路１１：ビデオピーク
検波回路 １２：差動増幅器１３：可変容量ダイオード
特許出願人 住友電気工業株式会社
（外２名）
、観／′（２）
（θ）
／
東２し１
／ｌ
２１９−
地、３関
范Δ１口
（ｄＢ＋。
一〒メー１（−を醪１′ｒ
■ｄ、茨＠（、ＭＨｚ）FIG. 1 is a diagram illustrating a conventional optical transmission system, FIG. 2 is a diagram illustrating an embodiment of a data transmission system having an amplitude-frequency characteristic variation compensation circuit 10 of the present invention, and FIG. FIG. 4, which is a diagram explaining the operation of the frequency characteristic fluctuation compensation circuit, is a diagram illustrating the fluctuation compensation level range in the present invention. 1: Pilot transmitter 2: Optical transmitter 3: Optical fiber 4: Optical receiver 5: Pilot signal bandpass filter 6: Detection circuit 7:
Head amplifier 10: Fluctuation compensation circuit 11: Video peak detection circuit 12: Differential amplifier 13: Variable capacitance diode Patent applicant Sumitomo Electric Industries, Ltd. (2 others), Kan/'(2) (θ) / Higashi 2shi 1/l 219- Earth, 3 Kanban Δ1 mouth (dB+. 1〒Me 1 (- 1'r ■d, Thorn @ (, MHz)
Claims (2)
して伝送する伝送システムにおいて、前記パイロット信
号のレベルを検出して自動利得制御を行なう受信機に、
ベースバンドビデオ信号とパイロット信号とのレベル比
較により振幅−周波数特注の変動を検出しその変動を補
償する振幅−周波数特性変動補償回路を備えることを特
徴とする振幅−周波数特性変動補償回路を有する伝送シ
ステム。(1) In a transmission system in which a pilot signal is superimposed on a baseband video signal and transmitted, a receiver that detects the level of the pilot signal and performs automatic gain control,
A transmission having an amplitude-frequency characteristic variation compensation circuit, which detects a custom-made amplitude-frequency variation by comparing the levels of a baseband video signal and a pilot signal, and includes an amplitude-frequency characteristic variation compensation circuit that compensates for the variation. system.
スパンドビデオ信号のピーク値を検出するピーク検波回
路と、該ピーク検波回路からのベースバンドビデオ信号
と出力パイロット信号とを比較してベースバンドビデオ
信号のレベル変動を検出する差動増幅器と、該差動増幅
器の出力に応答してその容量な変化する可変容量ダイオ
ードとから成ることを特徴とする振幅−周波数特性変動
補償回路を有する伝送システム。(2) In (1), the fluctuation compensation circuit includes a peak detection circuit that detects the peak value of the output baseband video signal, and compares the baseband video signal from the peak detection circuit with the output pilot signal to generate a baseband signal. Transmission having an amplitude-frequency characteristic fluctuation compensation circuit characterized by comprising a differential amplifier that detects level fluctuations of a band video signal, and a variable capacitance diode whose capacitance changes in response to the output of the differential amplifier. system.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57130902A JPS5921138A (en) | 1982-07-27 | 1982-07-27 | Transmitting system having amplitude-frequency characteristic variation compensating circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57130902A JPS5921138A (en) | 1982-07-27 | 1982-07-27 | Transmitting system having amplitude-frequency characteristic variation compensating circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS5921138A true JPS5921138A (en) | 1984-02-03 |
Family
ID=15045389
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57130902A Pending JPS5921138A (en) | 1982-07-27 | 1982-07-27 | Transmitting system having amplitude-frequency characteristic variation compensating circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5921138A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0163482A2 (en) * | 1984-05-24 | 1985-12-04 | Nec Corporation | Equalizer for frequency independent and dependent transmission loss components with a pilot used for the frequency independent component |
| JPS62137927A (en) * | 1985-12-11 | 1987-06-20 | Fujitsu Ltd | Cross modulation compensating device |
| JPS62216480A (en) * | 1987-03-03 | 1987-09-24 | Sony Corp | Television signal processing circuit |
-
1982
- 1982-07-27 JP JP57130902A patent/JPS5921138A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0163482A2 (en) * | 1984-05-24 | 1985-12-04 | Nec Corporation | Equalizer for frequency independent and dependent transmission loss components with a pilot used for the frequency independent component |
| JPS62137927A (en) * | 1985-12-11 | 1987-06-20 | Fujitsu Ltd | Cross modulation compensating device |
| JPH0378010B2 (en) * | 1985-12-11 | 1991-12-12 | Fujitsu Ltd | |
| JPS62216480A (en) * | 1987-03-03 | 1987-09-24 | Sony Corp | Television signal processing circuit |
| JPH0135545B2 (en) * | 1987-03-03 | 1989-07-26 | Sony Corp |
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