JPH053937B2 - - Google Patents
Info
- Publication number
- JPH053937B2 JPH053937B2 JP59249046A JP24904684A JPH053937B2 JP H053937 B2 JPH053937 B2 JP H053937B2 JP 59249046 A JP59249046 A JP 59249046A JP 24904684 A JP24904684 A JP 24904684A JP H053937 B2 JPH053937 B2 JP H053937B2
- Authority
- JP
- Japan
- Prior art keywords
- level
- pilot signal
- signal
- circuit
- variable
- 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 - Lifetime
Links
- 230000005540 biological transmission Effects 0.000 claims description 17
- 238000001514 detection method Methods 0.000 claims description 15
- 230000003287 optical effect Effects 0.000 claims description 14
- 238000006243 chemical reaction Methods 0.000 claims description 10
- 239000013307 optical fiber Substances 0.000 claims description 6
- 230000000903 blocking effect Effects 0.000 description 4
- 239000003990 capacitor Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000004891 communication Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 239000000470 constituent Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
- H04B10/66—Non-coherent receivers, e.g. using direct detection
- H04B10/69—Electrical arrangements in the receiver
- H04B10/693—Arrangements for optimizing the preamplifier in the receiver
- H04B10/6931—Automatic gain control of the preamplifier
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
- H04B10/66—Non-coherent receivers, e.g. using direct detection
- H04B10/69—Electrical arrangements in the receiver
- H04B10/691—Arrangements for optimizing the photodetector in the receiver
- H04B10/6911—Photodiode bias control, e.g. for compensating temperature variations
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Control Of Amplification And Gain Control (AREA)
- Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
- Optical Communication System (AREA)
Description
【発明の詳細な説明】
産業上の利用分野
本発明は、光フアイバ伝送路を用いた光通信方
式の光受信回路に関するものである。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical receiving circuit of an optical communication system using an optical fiber transmission line.
従来の技術
一般に、有線伝送方式の受信回路においては、
伝送路で生じる伝送損失の周波数特性を補償する
ため等化器が使用されており、光フアイバ伝送路
を用いた光通信方式の光受信回路においてもその
例外ではない。Conventional technology Generally, in a receiving circuit of a wired transmission system,
Equalizers are used to compensate for the frequency characteristics of transmission loss occurring in transmission lines, and optical receiving circuits for optical communication systems using optical fiber transmission lines are no exception.
また、光受信回路においては、平均値AGCと
称される自動利得制御が行われる場合が多い。 Further, in optical receiving circuits, automatic gain control called average value AGC is often performed.
上述の等化器と平均値AGC機能とを備えた従
来の光受信回路は、第３図に示すように構成され
ている。図中、２１は光フアイバ伝送路からの光
信号を電気信号に変換するAPD等の光電変換素
子、２２は前置増幅器、２３は光フアイバの伝送
損失の周波数特性を補償する等化器、２４は主増
幅器、２５は出力端子である。なお、２８は直流
阻止コンデンサであり、等化器２３へは直流成分
が除去された電気信号が供給される。 A conventional optical receiver circuit equipped with the above-mentioned equalizer and average value AGC function is configured as shown in FIG. In the figure, 21 is a photoelectric conversion element such as an APD that converts an optical signal from an optical fiber transmission line into an electrical signal, 22 is a preamplifier, 23 is an equalizer that compensates for the frequency characteristics of transmission loss of the optical fiber, and 24 is a main amplifier, and 25 is an output terminal. Note that 28 is a DC blocking capacitor, and the equalizer 23 is supplied with an electric signal from which a DC component has been removed.
また、２６は光電変換された電気信号の時間平
均値（直流レベル）を検出する直流レベル検出回
路であり、２７は直流レベル検出回路２６の出力
に応じた逆バイアスを光電変換素子２１に与える
直流−直流変換器である。すなわち直流レベル検
出回路２６と直流−直流変換器２７は、光電変換
された電気信号の時間平均値に応じた大きさの逆
バイアスを光電変換素子２１に印可することによ
り、この信号の時間平均値（直流成分）が一定と
なるように制御する平均値自動利得制御（平均値
AGC）を行う。 Further, 26 is a DC level detection circuit that detects the time average value (DC level) of the photoelectrically converted electric signal, and 27 is a DC level detection circuit that applies a reverse bias to the photoelectric conversion element 21 according to the output of the DC level detection circuit 26. - It is a DC converter. That is, the DC level detection circuit 26 and the DC-DC converter 27 apply a reverse bias of a magnitude corresponding to the time average value of the photoelectrically converted electrical signal to the photoelectric conversion element 21, thereby detecting the time average value of this signal. Average value automatic gain control (average value
AGC).
一般に、伝送損失の周波数特性は伝送路長によ
つて変化するので、これを補償するための等化器
の等化特性も個々の伝送路長に合わせて調整する
必要がある。 In general, the frequency characteristics of transmission loss change depending on the length of the transmission path, so the equalization characteristics of an equalizer to compensate for this must also be adjusted in accordance with the length of each transmission path.
第３図に例示したような従来回路では、上記等
化特性の調整は、個々の伝送路長に合わせて手動
で行うか、２周波のパイロツト信号を使用して自
動的に行つていた。 In the conventional circuit as illustrated in FIG. 3, the equalization characteristics are adjusted manually according to the length of each transmission path, or automatically using a two-frequency pilot signal.
発明が解決しようとする問題点
上述した等化特性の手動調整方式は、調整に手
間がかかり、また伝送特性の温度変動や経年変化
を補償できないという問題がある。Problems to be Solved by the Invention The above-described manual adjustment method for equalization characteristics has the problem that adjustment is time-consuming and it is not possible to compensate for temperature fluctuations and secular changes in transmission characteristics.
また、２周波のパイロツト信号を使用して自動
調整する方式は、帯域が広くなるため広帯域の増
幅器が必要となり、またパイロツト信号検出回路
も２系統必要であるため自動可変等化回路全体の
構成も複雑になるという欠点がある。 In addition, the automatic adjustment method using a dual-frequency pilot signal requires a wideband amplifier because the band is wide, and also requires two pilot signal detection circuits, which makes the overall configuration of the automatic variable equalization circuit difficult. The disadvantage is that it is complicated.
発明の構成
問題点を解決するための手段
上記従来技術の問題点を解決する本発明の光受
信回路は、平均値AGC回路と、等化器の出力か
らパイロツト信号のレベル又は搬送波の時間平均
値を検出する検出回路と、検出されたパイロツト
信号のレベル又は搬送波の時間平均値と上記平均
値AGC回路で検出された直流レベルとに基づき
上記等化器の等化特性を制御する手段とを備える
ように構成されている。Means for Solving the Constituent Problems of the Invention The optical receiving circuit of the present invention which solves the problems of the prior art described above includes an average value AGC circuit and a time average value of the pilot signal level or carrier wave from the output of the equalizer. and means for controlling the equalization characteristics of the equalizer based on the detected level of the pilot signal or the time average value of the carrier wave and the DC level detected by the average value AGC circuit. It is configured as follows.
すなわち、本発明の光受信回路は、平均値
AGC用に検出され所定値に保持される直流レベ
ルをパイロツト信号の低周波側であるかのように
利用することにより、そのような低周波側のパイ
ロツト信号を実際に送出し検出する際の伝送帯域
上の制約や回路の複雑化をともなうことなく、２
周波のパイロツト信号を使用した場合と同等の自
動可変等化特性を実現するように構成されてい
る。 That is, the optical receiving circuit of the present invention has an average value
By using the DC level detected for AGC and held at a predetermined value as if it were the low frequency side of the pilot signal, the transmission when actually sending out and detecting the pilot signal on the low frequency side 2 without bandwidth constraints or circuit complexity.
It is configured to realize automatically variable equalization characteristics equivalent to those obtained when a frequency pilot signal is used.
以下、本発明の作用を実施例によつて詳細に説
明する。 Hereinafter, the effects of the present invention will be explained in detail by way of examples.
実施例
第１図は本発明の一実施例の構成を示すブロツ
ク図である。Embodiment FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.
第１図において、１は光信号を電気信号に変換
する光電変換素子、２は前置増幅器、３は可変等
化器、４は主増幅器、５は出力端子、６は直流レ
ベル検出回路、７は直流−直流変換器、８は直流
阻止コンデンサである。 In FIG. 1, 1 is a photoelectric conversion element that converts an optical signal into an electric signal, 2 is a preamplifier, 3 is a variable equalizer, 4 is a main amplifier, 5 is an output terminal, 6 is a DC level detection circuit, and 7 is a DC-DC converter, and 8 is a DC blocking capacitor.
一方、１０はパイロツト信号を抽出する帯域通
過濾波器、１１は抽出されたパイロツト信号を増
幅する増幅器、１２は増幅されたパイロツト信号
の尖頭値を検出するピーク検出回路である。さら
に、１３は可変抵抗減衰器、１４はパイロツト信
号の尖頭値と可変抵抗減衰器１３を経た直流成分
とを比較し、その差を増幅する差動増幅器であ
る。 On the other hand, 10 is a band pass filter for extracting the pilot signal, 11 is an amplifier for amplifying the extracted pilot signal, and 12 is a peak detection circuit for detecting the peak value of the amplified pilot signal. Furthermore, 13 is a variable resistance attenuator, and 14 is a differential amplifier that compares the peak value of the pilot signal with the DC component that has passed through the variable resistance attenuator 13 and amplifies the difference.
第１図の回路において、図示しない光フアイバ
伝送路から光電変換素子１に光信号が入力する。
この光信号は、光電変換素子１で電気信号に変換
され、前置増幅器２で増幅され、直流阻止コンデ
ンサ８で直流成分が除去されたのち、可変等化器
３に供給される。伝送路損失の周波数性の補償す
るように等化された電気信号は、主増幅器４で増
幅され、出力端子５に出力される。 In the circuit shown in FIG. 1, an optical signal is input to the photoelectric conversion element 1 from an optical fiber transmission line (not shown).
This optical signal is converted into an electric signal by a photoelectric conversion element 1, amplified by a preamplifier 2, and after a DC component is removed by a DC blocking capacitor 8, it is supplied to a variable equalizer 3. The electrical signal equalized to compensate for the frequency nature of the transmission path loss is amplified by the main amplifier 4 and output to the output terminal 5.
一方、前置増幅器２の出力は、分岐され、比較
機能と積分機能を備えた直流レベル検出回路６に
供給される。ここで検出された直流レベルは、直
流−直流変換器７により、光電変換素子１に対す
る逆バイアスに変換される。この直流−直流変換
回路７は、直流レベル検出回路６の出力を所定値
に保持するような特性に設定されており、この結
果、前述のような平均値AGCが行われる。 On the other hand, the output of the preamplifier 2 is branched and supplied to a DC level detection circuit 6 having a comparison function and an integration function. The DC level detected here is converted into a reverse bias for the photoelectric conversion element 1 by the DC-DC converter 7. This DC-DC conversion circuit 7 is set to have a characteristic such that the output of the DC level detection circuit 6 is held at a predetermined value, and as a result, average value AGC as described above is performed.
また、主増幅器４の出力は、その一部が分岐さ
れ、帯域通過濾波器１０でパイロツト信号成分が
抽出され、抽出されたパイロツト信号に増幅器１
１で増幅された後、ピーク検出回路１２でその尖
頭値が検出される。このパイロツト信号の尖頭値
と、可変抵抗減衰器１３を経た直流レベル検出回
路６の出力が差動増幅器１４に供給される。差動
増幅器１４は、２入力の差電圧を可変等化器３に
供給することにより、等化特性を所定の特性に自
動調整する。 Further, a part of the output of the main amplifier 4 is branched, a pilot signal component is extracted by a bandpass filter 10, and the extracted pilot signal is passed to the amplifier 1.
After being amplified by 1, the peak value is detected by the peak detection circuit 12. The peak value of this pilot signal and the output of the DC level detection circuit 6 which has passed through the variable resistance attenuator 13 are supplied to a differential amplifier 14. The differential amplifier 14 automatically adjusts the equalization characteristic to a predetermined characteristic by supplying the differential voltage of two inputs to the variable equalizer 3.
これを第２図の振幅−周波数特性で説明する
と、図中の横軸は周波数、縦軸はこの周波数を有
する可変等化器３の出力の振幅である。図中の直
線ａは理想的に平坦な振幅−周波数特性である。
これに対して、曲線ｂは等化を行わない場合の振
幅−周波数特性である。信号の直流レベルA0は、
平均値AGC回路によつて一定となるように制御
されている。従つて、この直流レベルA0とパイ
ロツト信号の周波数pにおける振幅Ap（パイロツ
ト信号のレベル）とを比較し、その差（又は比）
を自動可変等化器３に供給する。 To explain this using the amplitude-frequency characteristic shown in FIG. 2, the horizontal axis in the figure is the frequency, and the vertical axis is the amplitude of the output of the variable equalizer 3 having this frequency. Straight line a in the figure represents an ideally flat amplitude-frequency characteristic.
On the other hand, curve b is the amplitude-frequency characteristic when equalization is not performed. The DC level of the signal A 0 is
The average value is controlled to be constant by the AGC circuit. Therefore, compare this DC level A 0 and the amplitude A p (level of the pilot signal) at the frequency p of the pilot signal, and calculate the difference (or ratio).
is supplied to the automatic variable equalizer 3.
自動可変等化器３は、差動増幅器１４から供給
される差電圧をゼロにする方向に等化特性を変化
させることにより、図中の曲線Ｃで例示するよう
な所定の振幅−周波数特性を実現する。このよう
な可変等化特性は、可変容量ダイオード等の可変
リアクタンス素子や可変抵抗器等を使用して容易
に実現できる。 The automatic variable equalizer 3 changes the equalization characteristic in the direction of zeroing the differential voltage supplied from the differential amplifier 14, thereby achieving a predetermined amplitude-frequency characteristic as exemplified by curve C in the figure. Realize. Such variable equalization characteristics can be easily realized using a variable reactance element such as a variable capacitance diode, a variable resistor, or the like.
以上、パイロツト信号を使用する構成を例示し
たが、これに代えて搬送波（キヤリア）の時間平
均レベルを使用する構成としてもよい。 Although the configuration that uses the pilot signal has been exemplified above, a configuration that uses the time average level of a carrier wave may be used instead.
発明の効果
以上詳細に説明したように、本発明の光受信回
路は、平均値AGC用に検出され所定値に保持さ
れる直流レベルをパイロツト信号の低周波側であ
るかのように利用する構成であるから、そのよう
な低周波側のパイロツト信号を実際に送出し検出
する際の伝送帯域上の制約や回路の複雑化を招く
ことなく、２周波のパイロツト信号を使用した場
合と同等の自動可変等化特性を実現できるという
利点がある。Effects of the Invention As explained in detail above, the optical receiving circuit of the present invention has a configuration in which the DC level detected for average value AGC and held at a predetermined value is used as if it were the low frequency side of the pilot signal. Therefore, when actually transmitting and detecting such a pilot signal on the low frequency side, there are no restrictions on the transmission band or complication of the circuit, and automatic detection equivalent to that when using a two-frequency pilot signal can be achieved. This has the advantage that variable equalization characteristics can be realized.
第１図は本発明の一実施例の構成を示すブロツ
ク図、第２図は第１図の回路の動作を説明するた
めの特性図、第３図は従来回路の構成を示すブロ
ツク図である。
１……光電変換素子、２……前置増幅器、３…
…可変等化器、４……主増幅器、５……出力端
子、６……直流レベル検出回路、７……直流−直
流変換器、８……直流阻止コンデンサ、１０……
帯域通過濾波器、１１……増幅器、１２……ピー
ク検出回路、１３……可変抵抗減衰器、１４……
差動増幅器。
FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a characteristic diagram for explaining the operation of the circuit shown in FIG. 1, and FIG. 3 is a block diagram showing the configuration of a conventional circuit. . 1...Photoelectric conversion element, 2...Preamplifier, 3...
...Variable equalizer, 4...Main amplifier, 5...Output terminal, 6...DC level detection circuit, 7...DC-DC converter, 8...DC blocking capacitor, 10...
Bandpass filter, 11...Amplifier, 12...Peak detection circuit, 13...Variable resistance attenuator, 14...
Differential amplifier.
Claims (1)
気信号に変換する光電変換素子と、 該光電変換された電気信号の平均直流レベルを
検出して該平均直流レベルが所定の値となるよう
に前記光電変換素子の動作を制御する手段と、 前記光電変換された電気信号を等化する可変等
化器と、 該可変等化器の出力から前記光信号に含まれる
所定の周波数成分を有するパイロツト信号又は搬
送波を検出し、前記パイロツト信号のレベル又は
搬送波の時間平均レベルを検出する検出回路と、 該検出されたパイロツト信号のレベル間又は搬
送波の時間平均レベル及び前記検出された平均直
流レベルに基づき前記可変等化器の等化特性を制
御する手段とを備えたことを特徴とする光受信回
路。[Scope of Claims] 1. A photoelectric conversion element that converts an optical signal output from an optical fiber transmission line into an electrical signal, and detects the average DC level of the photoelectrically converted electrical signal and determines whether the average DC level is a predetermined level. a variable equalizer for equalizing the photoelectrically converted electrical signal; a detection circuit that detects a pilot signal or a carrier wave having a frequency component and detects the level of the pilot signal or the time average level of the carrier wave; and means for controlling equalization characteristics of the variable equalizer based on an average DC level.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59249046A JPS61127237A (en) | 1984-11-26 | 1984-11-26 | Optical reception circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59249046A JPS61127237A (en) | 1984-11-26 | 1984-11-26 | Optical reception circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61127237A JPS61127237A (en) | 1986-06-14 |
| JPH053937B2 true JPH053937B2 (en) | 1993-01-18 |
Family
ID=17187203
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59249046A Granted JPS61127237A (en) | 1984-11-26 | 1984-11-26 | Optical reception circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61127237A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS641341A (en) * | 1987-06-23 | 1989-01-05 | Sumitomo Electric Ind Ltd | Optical transmitting-receiving circuit |
-
1984
- 1984-11-26 JP JP59249046A patent/JPS61127237A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61127237A (en) | 1986-06-14 |
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