JPS6040223B2 - Automatic threshold control method for optical communication receiving system - Google Patents
Automatic threshold control method for optical communication receiving systemInfo
- Publication number
- JPS6040223B2 JPS6040223B2 JP55090882A JP9088280A JPS6040223B2 JP S6040223 B2 JPS6040223 B2 JP S6040223B2 JP 55090882 A JP55090882 A JP 55090882A JP 9088280 A JP9088280 A JP 9088280A JP S6040223 B2 JPS6040223 B2 JP S6040223B2
- Authority
- JP
- Japan
- Prior art keywords
- light
- output
- optical
- receiving element
- level
- 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
Links
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
-
- 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)
- Light Receiving Elements (AREA)
- Optical Communication System (AREA)
Description
【発明の詳細な説明】
本発明はディジタル光空間通信受信器に関するものであ
る。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a digital optical space communications receiver.
近距離間（１物以内）の通信においては、コスト面、敷
設面で、また可搬性という点でも光空間通信が最適であ
る。For short-distance communication (within one object), optical space communication is optimal in terms of cost, installation, and portability.
通信方式としてはアナログ信号、ディジタル信号で発光
素子を直接駆動するアナログＩＭ、ディジタルＩＭ方式
があるが、伝送品質の点で後者が多く用いられている。
送信器側でパルス列を送っても、伝送路（空間）、受信
器アンプによってかなり積分された波形となる。そこで
もとの信号に変換する為、識別再生器が用いられる。も
し入力光が信号光のみなら、第１図に示す様に、識別再
生器６の入力信号を低域炉波器よりなるピーク検出器８
に通して、平均値検出を行ない、さらに自動しきい値制
御、自動利得制御を行なう事により、広いダイナミック
レンジを得る事ができる。第１図の従来例について説明
すると、光学フィル夕１を通過した光は、受光素子とし
てのＡＰＤ２により光電変換増幅され、プリァンプ３、
メインアンプ４によって更に増幅される。Communication methods include analog IM and digital IM, in which light emitting elements are directly driven by analog and digital signals, and the latter is often used in terms of transmission quality.
Even if a pulse train is sent on the transmitter side, the waveform will be considerably integrated by the transmission path (space) and receiver amplifier. Therefore, an identification regenerator is used to convert it back to the original signal. If the input light is only signal light, as shown in FIG.
A wide dynamic range can be obtained by performing average value detection, and further performing automatic threshold control and automatic gain control. To explain the conventional example shown in FIG. 1, light passing through an optical filter 1 is photoelectrically converted and amplified by an APD 2 as a light receiving element, and a preamplifier 3,
It is further amplified by the main amplifier 4.
メインアンプ４の出力は等化器５を通って識別再生器６
に入力される。等化器５の出力の一部はピーク検出器８
を通り、メインアンプ４のゲインを制御する。また、ピ
ーク検出器８の出力の一部は、ＤＣ−ＤＣコンバータ７
を通り、ＡＰＤ２の逆バイアス電圧を制御する。識別再
生器６は入力信号レベルとしきし、値を比較し、再生パ
ルスを出力するのであるが、ピーク検出器８の出力によ
り識別再生器６のしきし・値を制御する事によって、識
別再生器６の入力レベル変動に対して広いダイナミック
レンジを得ている。この従来例においては、ＡＰＤ２へ
の入力光が信号光のみならば効果はある。The output of the main amplifier 4 passes through an equalizer 5 to an identification regenerator 6.
is input. A portion of the output of the equalizer 5 is sent to the peak detector 8
controls the gain of the main amplifier 4. Further, a part of the output of the peak detector 8 is transmitted to the DC-DC converter 7
, and controls the reverse bias voltage of APD2. The discrimination regenerator 6 compares the threshold value with the input signal level and outputs a reproduction pulse. A wide dynamic range is obtained for fluctuations in the input level of the device 6. This conventional example is effective if the input light to the APD 2 is only the signal light.
しかし、実際には光空間通信の場合、信号光以外に雑音
背景光（例えば太陽光線、人工光源）が存在し、これら
が信号光と共に入射して来る。従って等化器５の出力レ
ベルは信号光と雑音光の和のレベルとなり、信号光が弱
くなっても、雑音光が強くなれば、レベルが大きくなり
、識別再生器６のしきし、値制御は悪化する方へ働く。
すなわち一般に、外来雑音光の影響（特に太陽光）軽減
のため第４図の如き特性を有する短波長カットフィル夕
（入ｓは信号光波長を示す）、または、バンドパスフィ
ルタ（干渉フィル夕）が用いられるが、透過波長帯域の
透過率は、前者が９５％後者が５０％位であり、主に前
者が使用されている。However, in reality, in the case of optical space communication, there is noise background light (for example, sunlight, artificial light sources) in addition to the signal light, and these light are incident together with the signal light. Therefore, the output level of the equalizer 5 is the sum of the signal light and the noise light, and even if the signal light becomes weak, if the noise light becomes strong, the level increases, and the threshold of the discrimination regenerator 6 and the value control works to make things worse.
That is, generally, in order to reduce the influence of external noise light (especially sunlight), a short wavelength cut filter (input s indicates the signal light wavelength) or a band pass filter (interference filter) having the characteristics as shown in Fig. 4 is used. However, the transmittance in the transmission wavelength band is about 95% for the former and 50% for the latter, and the former is mainly used.
そして光電変換の際生ずる散弾雑音は入射光パワーの平
方根に比例するため、背景光が強ければ強い程、ｓ／Ｎ
は悪化する。この事により、識別再生器６の入力信号を
平均値検出して、識別再生器６のしまい値を制御すると
いう第１図に示す従来の方式では、背景雑音光が存在し
かつ大きく変化する状態で使用すると、伝送品質が著し
く悪化する。本発明は、外釆雑音光レベルと信号光レベ
ルを比較し、識別再生器のしきし、値を制御して上記の
欠点を解決しようとするものであり、以下その一実施例
を図面に基づいて説明する。Since the shot noise generated during photoelectric conversion is proportional to the square root of the incident light power, the stronger the background light, the higher the s/N
becomes worse. As a result, in the conventional method shown in FIG. 1, which detects the average value of the input signal of the discrimination and regenerator 6 and controls the end value of the discrimination and regenerator 6, the background noise light exists and changes greatly. If used in , transmission quality will deteriorate significantly. The present invention attempts to solve the above-mentioned drawbacks by comparing the external noise light level and the signal light level and controlling the threshold and value of the discrimination regenerator. I will explain.
第２図において、光学フィル夕１１は第３図の如き信号
光波長入ｓを遮断する特性を持ち、この光学フィル夕１
１と、ＡＰＤ１ ２、プリアンプ１３、メインアンプ
１４、低域炉波器よりなるピーク検出器１８とによって
、外来光レベルを測定する。In FIG. 2, the optical filter 11 has a characteristic of blocking the input signal light wavelength s as shown in FIG.
1 and a peak detector 18 consisting of an APD 1 2, a preamplifier 13, a main amplifier 14, and a low-frequency wave detector.
一方光学フィル夕２１は従来と同じ第４図の如き特性を
持ち、この光学フィル夕２１と、ＡＰＤ２ ２、プリア
ンプ２ ３、メインアンプ２４、等化器２５、低減炉波
器よりなるピーク検出器２８とによって出力レベルを得
、この出力レベルと前記外来光レベルとを比較器２９で
比較し、最適なしきし、値となる様に制御する。なお、
第２図においてＡＰＤを使用したが、ＰＤを使用しても
よい。On the other hand, the optical filter 21 has the same characteristics as the conventional one as shown in FIG. The output level is obtained by 28, and this output level is compared with the external light level by a comparator 29, and control is performed to obtain an optimum threshold value. In addition,
Although APD is used in FIG. 2, PD may also be used.
この場合、ＡＰＤ逆バイアス制御用のＤＣ−ＤＣコンバ
ータは不要となる。また、受光素子は同じ方向を向け、
可能なかぎり接・近させると、一層の効果がある。以上
の様に、本発明は外来雑音光レベルを考慮して、しきし
・値を制御するものであり、これにより信号光以外の雑
音背景光によって影響されることなく、広いダイナミッ
クレンジを可能とし、光空間通信に対する効果は非常に
大きいものがある。In this case, a DC-DC converter for APD reverse bias control becomes unnecessary. Also, the light receiving elements are oriented in the same direction,
The effect will be even greater if you bring it as close as possible. As described above, the present invention controls the threshold value in consideration of the external noise light level, and thereby enables a wide dynamic range without being affected by noise background light other than signal light. , has a very large effect on optical space communications.
第１図は従来の光受信器の自動しきい値制御方式を示す
ブロック図、第２図は本発明の一実施例としての光受信
器の自動しきし、値制御方式を示すフロック図、第３図
、第４図は光学フィル夕の特性を説明する図である。
１１，２１・・・・・・光学フィル夕、１２，２２・・
・・・・ＡＰＤ、１ ４，２４……可変利得メインアン
プ、２６・・・・・・識別再生器、２７・・・・・・Ｄ
Ｃ−ＤＣコンパ−夕、１８，２８・・・・・・ピーク検
出器、２９・・・・・・比較器。
第１図
第２図
第３図
第４図FIG. 1 is a block diagram showing an automatic threshold value control method for a conventional optical receiver, and FIG. 2 is a block diagram showing an automatic threshold value control method for an optical receiver as an embodiment of the present invention. 3 and 4 are diagrams for explaining the characteristics of the optical filter. 11, 21... Optical filter, 12, 22...
...APD, 1 4,24...Variable gain main amplifier, 26...Identification regenerator, 27...D
C-DC comparator, 18, 28...Peak detector, 29...Comparator. Figure 1 Figure 2 Figure 3 Figure 4
Claims (1)
受光素子の出力を増幅する可変利得増幅器と、識別再生
器と、可変利得増幅器の出力レベルを検知し可変利得増
幅器の利得を制御する低域濾波器とを具備する光信号受
信器であつて、信号光を遮断し、外来雑音光を通過させ
る光学フイルタと、受光素子と、受光素子の出力を増幅
する増幅器と、増幅器の出力レベルを検知する低域濾波
器とを具備する外来雑音光レベル測定器を設け、該外来
雑音光レベル測定器の出力と光信号受信器の低域濾波器
出力を比較器に入力し、該比較器の出力電圧によつて識
別再生器のしきい値を制御するようにした事を特徴とす
る光通信受信系の自動しきい値制御方式。1. An optical filter that allows signal light to pass through, a light receiving element,
An optical signal receiver comprising a variable gain amplifier that amplifies the output of a light receiving element, an identification regenerator, and a low pass filter that detects the output level of the variable gain amplifier and controls the gain of the variable gain amplifier, Extraneous noise light level measurement comprising an optical filter that blocks signal light and passes extraneous noise light, a light receiving element, an amplifier that amplifies the output of the light receiving element, and a low pass filter that detects the output level of the amplifier. The output of the external noise optical level measuring device and the low-pass filter output of the optical signal receiver are input to a comparator, and the threshold of the discrimination regenerator is controlled by the output voltage of the comparator. An automatic threshold control method for an optical communication receiving system, which is characterized by:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP55090882A JPS6040223B2 (en) | 1980-07-02 | 1980-07-02 | Automatic threshold control method for optical communication receiving system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP55090882A JPS6040223B2 (en) | 1980-07-02 | 1980-07-02 | Automatic threshold control method for optical communication receiving system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5715544A JPS5715544A (en) | 1982-01-26 |
| JPS6040223B2 true JPS6040223B2 (en) | 1985-09-10 |
Family
ID=14010807
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP55090882A Expired JPS6040223B2 (en) | 1980-07-02 | 1980-07-02 | Automatic threshold control method for optical communication receiving system |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6040223B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0532017Y2 (en) * | 1987-07-31 | 1993-08-17 |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2674494B2 (en) * | 1993-12-27 | 1997-11-12 | 日本電気株式会社 | Optical receiving circuit |
| JP4992129B2 (en) * | 2007-07-19 | 2012-08-08 | 株式会社豊田中央研究所 | Optical communication device |
-
1980
- 1980-07-02 JP JP55090882A patent/JPS6040223B2/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0532017Y2 (en) * | 1987-07-31 | 1993-08-17 |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5715544A (en) | 1982-01-26 |
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