JPH0856200A - Agc method for optical receiver for catv - Google Patents

Agc method for optical receiver for catv

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Publication number
JPH0856200A
JPH0856200A JP6212059A JP21205994A JPH0856200A JP H0856200 A JPH0856200 A JP H0856200A JP 6212059 A JP6212059 A JP 6212059A JP 21205994 A JP21205994 A JP 21205994A JP H0856200 A JPH0856200 A JP H0856200A
Authority
JP
Japan
Prior art keywords
signal
agc
voltage
attenuator
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.)
Granted
Application number
JP6212059A
Other languages
Japanese (ja)
Other versions
JP3479124B2 (en
Inventor
Hajime Odaka
肇 小高
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.)
Miharu Communications Co Ltd
Original Assignee
Miharu Communications Co 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
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Application filed by Miharu Communications Co Ltd filed Critical Miharu Communications Co Ltd
Priority to JP21205994A priority Critical patent/JP3479124B2/en
Publication of JPH0856200A publication Critical patent/JPH0856200A/en
Application granted granted Critical
Publication of JP3479124B2 publication Critical patent/JP3479124B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Abstract

PURPOSE:To make the size of the optical receiver small and to reduce the cost by adjusting automatically the signal level by monitoring the level of the optical signal received by a light receiving element at a monitor terminal provided to the light receiving element and applying AGC to a electric signal converted from the monitor signal. CONSTITUTION:A variable attenuator 2 is a voltage controlled attenuator and its attenuation is continuously varied varying the voltage applied to the attenuator. A monitor signal outputted from a monitor terminal 3 of the light receiving element 1 is given to a control circuit 12, which generates a voltage (AGC voltage) in response to a level of the received monitor signal and applies the voltage to the attenuator 2. When the AGC voltage of the control circuit 12 is applied to the attenuator 2, the attenuation of the attenuator 2 is adjusted depending on the AGC voltage. The change quantity of the AGC voltage or the attenuation characteristic of the attenuator 2 is adjusted so that the level of the electric signal outputted from the amplifier 11 becomes constant by eliminating the fluctuation in the optical signal. Thus, even in the case of the CATV system having no pilot signal, the AGC function is available.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明はＣＡＴＶシステムの光通
信の分野で使用されるＣＡＴＶ用光受信機に関するもの
であり、光受信機で受光される光信号にレベル変動があ
っても同受信機から出力される電気信号のレベルが一定
に保たれるようにするためのＡＧＣ方法に関するもので
ある。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CATV optical receiver used in the field of optical communication of a CATV system, and the same receiver even if the optical signal received by the optical receiver varies in level. The present invention relates to an AGC method for keeping a level of an electric signal output from the AGC constant.

【０００２】[0002]

【従来の技術】光伝送システムでは光受信機の受光レベ
ルが変化すると、光受信機から出力される電気信号のレ
ベルも変化してしまう。しかし受光レベルが変化しても
電気信号の出力レベルは一定にするのが望ましい。そこ
で従来は、光受信機を図２に示すような構成にして出力
レベルを調整していた。2. Description of the Related Art In an optical transmission system, when the light receiving level of an optical receiver changes, the level of an electric signal output from the optical receiver also changes. However, it is desirable to keep the output level of the electric signal constant even if the light receiving level changes. Therefore, conventionally, the output level has been adjusted by configuring the optical receiver as shown in FIG.

【０００３】図２は光通信の分野で使用される従来型の
光受信機の概略図である。この光受信機は、光ファイバ
により伝送されてくる光信号を受光素子（フォトダイオ
ード）Ａで電気信号に変換し、この電気信号をＲＦアン
プＢ−可変減衰器Ｃ−分岐器ＤーＲＦアンプＥの系路で
増幅している。この光受信機では前記分岐器Ｄで信号を
分岐し、この分岐信号をＳＡＷフィルタ（バンドパスフ
ィルタの一種）Ｆに通してパイロット信号を取り出し、
このパイロット信号を検波器Ｇで検波してＡＧＣ電圧を
発生し、このＡＧＣ電圧に基づいて制御回路Ｈが可変減
衰器Ｃの減衰量を自動的に可変させて電気信号のレベル
を調整（ＡＧＣ）している。なお、前記可変減衰器Ｃ、
分岐器Ｄ、ＳＡＷフィルタＦ、検波回路Ｇ、制御回路Ｈ
で構成される回路は一般にＡＧＣ回路と呼ばれている。FIG. 2 is a schematic diagram of a conventional optical receiver used in the field of optical communication. In this optical receiver, a light receiving element (photodiode) A converts an optical signal transmitted through an optical fiber into an electric signal, and the electric signal is RF amplifier B-variable attenuator C-brancher D-RF amplifier E. It is amplified in the path of. In this optical receiver, the signal is branched by the branching device D, and the branched signal is passed through a SAW filter (a kind of bandpass filter) F to extract a pilot signal,
This pilot signal is detected by the detector G to generate an AGC voltage, and the control circuit H automatically changes the attenuation amount of the variable attenuator C based on the AGC voltage to adjust the level of the electric signal (AGC). are doing. The variable attenuator C,
Brancher D, SAW filter F, detection circuit G, control circuit H
The circuit constituted by is generally called an AGC circuit.

【０００４】[0004]

【発明が解決しようとする課題】しかしながら、従来型
のＣＡＴＶ用光受信機では受信信号のＡＧＣにパイロッ
ト信号を用いるため、次のような問題があった。 ．パイロット信号を送信しないＣＡＴＶシステム、例
えば難視共聴システムでは図２の光受信機ではＡＧＣを
かけることができない。 ．ＡＧＣ回路の構成が複雑であり、光受信機の小型
化、コストの低減、メンテナンスの簡易化を阻害してい
た。 ．特にＡＧＣ回路を構成する部品のうち、ＳＡＷフィ
ルタＦは高価であり、コスト低減に難を有していた。However, since the conventional CATV optical receiver uses the pilot signal for the AGC of the received signal, it has the following problems. ． In a CATV system that does not transmit a pilot signal, for example, a visually impaired common hearing system, the optical receiver of FIG. 2 cannot apply AGC. ． The configuration of the AGC circuit is complicated, which hinders downsizing of the optical receiver, cost reduction, and simplification of maintenance. ． In particular, of the components that make up the AGC circuit, the SAW filter F is expensive and has a difficulty in cost reduction.

【０００５】本発明の目的は、パイロット信号がないＣ
ＡＴＶシステムでも信号レベルを自動調整でき、光受信
機の小型化、低コスト化、メンテナンスの簡易化に寄与
できるＣＡＴＶ用光受信機のＡＧＣ方法を提供すること
にある。An object of the present invention is to have a C without pilot signal.
It is an object of the present invention to provide an AGC method for a CATV optical receiver, which can automatically adjust the signal level even in an ATV system and can contribute to downsizing, cost reduction, and simplification of maintenance of the optical receiver.

【０００６】[0006]

【課題を解決するための手段】本発明のＣＡＴＶ用光受
信機のＡＧＣ方法は図１に示すように、ＣＡＴＶ用光受
信機に設けられた受光素子１に受光される光信号のレベ
ルを、同受光素子１に設けられたモニタ端子３でモニタ
し、このモニタ端子３からのモニタ信号で、前記受光素
子１で光信号から電気信号に変換された信号にＡＧＣを
かけるようにしたことを特徴とするものである。As shown in FIG. 1, the AGC method for a CATV optical receiver according to the present invention, as shown in FIG. 1, determines the level of an optical signal received by a light receiving element 1 provided in the CATV optical receiver. A monitor terminal 3 provided in the light receiving element 1 is used for monitoring, and a monitor signal from the monitor terminal 3 is used to apply AGC to a signal converted from an optical signal to an electric signal by the light receiving element 1. It is what

【０００７】[0007]

【作用】本発明のＣＡＴＶ用光受信機のＡＧＣ方法で
は、受光素子１に受光される光信号のレベルを、同受光
素子１に設けられたモニタ端子３でモニタし、このモニ
タ端子３からのモニタ信号で、受光素子１により光信号
から電気信号に変換された信号にＡＧＣをかけるように
したため、パイロット信号がなくともＡＧＣをかけるこ
とができる。In the AGC method for the optical receiver for CATV of the present invention, the level of the optical signal received by the light receiving element 1 is monitored by the monitor terminal 3 provided in the light receiving element 1, and the level from the monitor terminal 3 is monitored. Since the AGC is applied to the signal converted from the optical signal to the electric signal by the light receiving element 1 by the monitor signal, the AGC can be applied without the pilot signal.

【０００８】[0008]

【実施例】図１は本発明のＣＡＴＶ用光受信機のＡＧＣ
方法の一実施例を示したものである。このＡＧＣ方法で
は、光ファイバにより伝送される光信号を受光素子（例
えばフォトダイオード）１で電気信号に変換し、同電気
信号を２つＲＦアンプ１０、１１で増幅できるようにし
てある。またこのＲＦアンプ１０、１１間には可変減衰
器２を配置してあり、この可変減衰器２で電気信号のレ
ベルを任意に加減できるようにしてある。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an AGC of an optical receiver for CATV of the present invention.
1 illustrates an example of a method. In this AGC method, an optical signal transmitted by an optical fiber is converted into an electric signal by a light receiving element (for example, photodiode) 1, and the electric signal can be amplified by two RF amplifiers 10 and 11. A variable attenuator 2 is arranged between the RF amplifiers 10 and 11 so that the variable attenuator 2 can arbitrarily adjust the level of the electric signal.

【０００９】前記受光素子１は、受光した光信号のレベ
ルをモニタすることができるモニタ端子３を備えたもの
であり、このモニタ端子３からは前記光信号のレベルと
対応した電気信号（モニタ信号）が出力されるようにし
てある。このモニタ信号は、例えば光信号のレベルが低
いと小さい電流としてモニタ端子３から出力され、光信
号のレベルが大きいと大きい電流としてモニタ端子３か
ら出力されるものである。The light receiving element 1 is provided with a monitor terminal 3 capable of monitoring the level of the received optical signal. From the monitor terminal 3, an electric signal (monitor signal) corresponding to the level of the optical signal is provided. ) Is output. This monitor signal is, for example, output from the monitor terminal 3 as a small current when the level of the optical signal is low, and is output from the monitor terminal 3 as a large current when the level of the optical signal is high.

【００１０】前記可変減衰器２は電圧制御型のものであ
り、印加する電圧を可変することによりその減衰量を連
続して可変させることができる。そこで前記受光素子１
のモニタ端子３から出力されるモニタ信号を制御回路１
２に入力し、この制御回路１２で前記光信号のレベルに
応じた電圧（ＡＧＣ電圧）を発生し、このＡＧＣ電圧を
可変減衰器２に印加するようにしてある。制御回路１２
のＡＧＣ電圧が可変減衰器２に印加されると、このＡＧ
Ｃ電圧に応じて可変減衰器２の減衰量が加減されるが、
同ＡＧＣ電圧の変化量或は可変減衰器２の減衰特性は、
光信号の変動を解消して、アンプ１１から出力される電
気信号のレベルを一定にするように調整してある。The variable attenuator 2 is of a voltage control type, and the amount of attenuation can be continuously varied by varying the applied voltage. Therefore, the light receiving element 1
The monitor signal output from the monitor terminal 3 of the control circuit 1
2, the control circuit 12 generates a voltage (AGC voltage) according to the level of the optical signal, and the AGC voltage is applied to the variable attenuator 2. Control circuit 12
When the AGC voltage of is applied to the variable attenuator 2, this AG
The attenuation amount of the variable attenuator 2 is adjusted according to the C voltage,
The amount of change in the AGC voltage or the attenuation characteristic of the variable attenuator 2 is
The fluctuation of the optical signal is eliminated, and the level of the electric signal output from the amplifier 11 is adjusted to be constant.

【００１１】[0011]

【発明の効果】本発明のＣＡＴＶ用光受信機のＡＧＣ方
法では下記の効果がある。 ．パイロット信号が不要であり、このためパイロット
信号がないＣＡＴＶシステムでもＡＧＣ機能を持たせた
光受信機を使用できるようになる。 ．ＳＡＷフィルタ、検波回路等が不要なため、ＡＧＣ
回路の構成が簡潔なものとなり、光受信機の小型化、低
コスト化、メンテナンスの簡易化が期待できる。The AGC method of the CATV optical receiver of the present invention has the following effects. ． No pilot signal is required, so that a CATV system without a pilot signal can use an optical receiver having an AGC function. ． Since the SAW filter and the detection circuit are unnecessary, AGC
It is expected that the circuit configuration will be simple, the optical receiver will be smaller, the cost will be reduced, and the maintenance will be simplified.

【図面の簡単な説明】[Brief description of drawings]

【図１】本発明のＣＡＴＶ用光受信機のＡＧＣ方法の一
実施例を示した回路図。FIG. 1 is a circuit diagram showing an embodiment of an AGC method of an optical receiver for CATV of the present invention.

【図２】従来のＣＡＴＶ用光受信機のＡＧＣ方法の一例
を示した回路図。FIG. 2 is a circuit diagram showing an example of an AGC method of a conventional CATV optical receiver.

【符号の説明】[Explanation of symbols]

１ 受光素子 ３ モニタ端子 1 Light receiving element 3 Monitor terminal

Claims (1)

【特許請求の範囲】[Claims] 【請求項１】 ＣＡＴＶ用光受信機に設けられた受光素
子（１）に受光される光信号のレベルを、同受光素子
（１）に設けられたモニタ端子（３）でモニタし、この
モニタ端子（３）からのモニタ信号で、前記受光素子
（１）で光信号から電気信号に変換された信号にＡＧＣ
をかけるようにしたことを特徴とするＣＡＴＶ用光受信
機のＡＧＣ方法。1. A level of an optical signal received by a light receiving element (1) provided in a CATV optical receiver is monitored by a monitor terminal (3) provided in the light receiving element (1), and this monitor is monitored. The monitor signal from the terminal (3) converts the optical signal from the optical signal in the light receiving element (1) into an electric signal,
An AGC method for a CATV optical receiver, which is characterized in that
JP21205994A 1994-08-12 1994-08-12 AGC method for CATV optical receiver Expired - Lifetime JP3479124B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP21205994A JP3479124B2 (en) 1994-08-12 1994-08-12 AGC method for CATV optical receiver

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP21205994A JP3479124B2 (en) 1994-08-12 1994-08-12 AGC method for CATV optical receiver

Publications (2)

Publication Number Publication Date
JPH0856200A true JPH0856200A (en) 1996-02-27
JP3479124B2 JP3479124B2 (en) 2003-12-15

Family

ID=16616192

Family Applications (1)

Application Number Title Priority Date Filing Date
JP21205994A Expired - Lifetime JP3479124B2 (en) 1994-08-12 1994-08-12 AGC method for CATV optical receiver

Country Status (1)

Country Link
JP (1) JP3479124B2 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003018095A (en) * 2001-07-04 2003-01-17 Synclayer Inc Optical receiver
JP2006262353A (en) * 2005-03-18 2006-09-28 Yagi Antenna Co Ltd Optical receiver
JP2007074427A (en) * 2005-09-07 2007-03-22 Maspro Denkoh Corp Optical receiver, and squelch operation method of optical receiver
JP2007312282A (en) * 2006-05-22 2007-11-29 Hochiki Corp Optical receiver
JP2013026636A (en) * 2011-07-14 2013-02-04 Hochiki Corp Optical receiver

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5379453A (en) 1976-12-24 1978-07-13 Fujitsu Ltd Automatic gain control system
JPS5774523U (en) 1980-10-22 1982-05-08
JPS57168513A (en) 1981-04-09 1982-10-16 Nec Corp Automatic gain controlling system of optical receiver
JPS62183423U (en) 1986-05-09 1987-11-20
JPS6447188A (en) 1987-08-17 1989-02-21 Miharu Communication Agc method for amplifier in catv system
JPH0133058B2 (en) 1982-01-14 1989-07-11 Hitachi Cable
JPH0377416A (en) 1989-08-19 1991-04-03 Aichi Denshi Kk Automatic gain control circuit
JPH05102931A (en) * 1991-10-11 1993-04-23 Matsushita Electric Ind Co Ltd Optical agc circuit
JPH05267766A (en) * 1992-03-23 1993-10-15 Nec Corp Light transmission device

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5379453A (en) 1976-12-24 1978-07-13 Fujitsu Ltd Automatic gain control system
JPS5774523U (en) 1980-10-22 1982-05-08
JPS57168513A (en) 1981-04-09 1982-10-16 Nec Corp Automatic gain controlling system of optical receiver
JPH0133058B2 (en) 1982-01-14 1989-07-11 Hitachi Cable
JPS62183423U (en) 1986-05-09 1987-11-20
JPS6447188A (en) 1987-08-17 1989-02-21 Miharu Communication Agc method for amplifier in catv system
JPH0377416A (en) 1989-08-19 1991-04-03 Aichi Denshi Kk Automatic gain control circuit
JPH05102931A (en) * 1991-10-11 1993-04-23 Matsushita Electric Ind Co Ltd Optical agc circuit
JPH05267766A (en) * 1992-03-23 1993-10-15 Nec Corp Light transmission device

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003018095A (en) * 2001-07-04 2003-01-17 Synclayer Inc Optical receiver
JP2006262353A (en) * 2005-03-18 2006-09-28 Yagi Antenna Co Ltd Optical receiver
JP4620509B2 (en) * 2005-03-18 2011-01-26 八木アンテナ株式会社 Optical receiver
JP2007074427A (en) * 2005-09-07 2007-03-22 Maspro Denkoh Corp Optical receiver, and squelch operation method of optical receiver
JP2007312282A (en) * 2006-05-22 2007-11-29 Hochiki Corp Optical receiver
JP2013026636A (en) * 2011-07-14 2013-02-04 Hochiki Corp Optical receiver

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