JPS5928098B2 - Optical cable transmission method - Google Patents
Optical cable transmission methodInfo
- Publication number
- JPS5928098B2 JPS5928098B2 JP56037277A JP3727781A JPS5928098B2 JP S5928098 B2 JPS5928098 B2 JP S5928098B2 JP 56037277 A JP56037277 A JP 56037277A JP 3727781 A JP3727781 A JP 3727781A JP S5928098 B2 JPS5928098 B2 JP S5928098B2
- Authority
- JP
- Japan
- Prior art keywords
- optical
- signal
- semiconductor laser
- signals
- television
- 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
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0298—Wavelength-division multiplex systems with sub-carrier multiplexing [SCM]
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Optical Communication System (AREA)
Description
【発明の詳細な説明】
本発明は多チャンネルのテレビ信号を伝送する光ケーブ
ル伝送方式に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical cable transmission system for transmitting multi-channel television signals.
従来のこの種の方式は第１図に示すようにｎチャンネル
のテレビ信号を例えば商用放送用のＶ■’帯で周波数分
割多重し多重化されたテレビ信号で１個の半導体レーザ
を駆動するように構成されていた。As shown in Figure 1, this type of conventional system frequency-division multiplexes an n-channel television signal, for example, in the V'' band for commercial broadcasting, and drives one semiconductor laser with the multiplexed television signal. It was composed of
この構成の場合多重化チャンネル数ｎ）及び多重化する
キャリア周波数の配置にもよるが、、通常の日本での商
用放送に用いられているＶＨＦ帯の周波数配置を例にと
ればチャンネル１〜３のローバンドの２次高調波ひずみ
がナヤンネル５〜チャンネル１１のハイバンドの帯域に
落ち込み、またローバンドとハイバンドの二次ビードが
各々帯・ 域内に落ち込むため半導体レーザに課せられ
る直線性が非常に厳しかつた（第２図）。更に１チャン
ネル当りの光の変調度が小さくなり半導体レーザの内部
雑音などによつて１チャンネル当りの信号対雑音比が受
光レベルを上げても飽和特性を示フ し送り側の信号対
雑音比で制限されて十分な信号対雑音比を得ることがで
きないなどの欠点を有していた。本発明はこれらの欠点
を改善することを目的とし、複数の半導体レーザを各々
相異なるチヤンネ・ ルのテレビ信号で駆動し、しかる
後光ミキサーで受信側に分配するもので、その特徴は、
相異なるキャリア周波数で変調され変調波のスペクトル
が相互に重ならない様に設定された複数のテレビ信号又
はベースバンドテレビ信号を入力信号とし、ワ 各テレ
ビ入力信号と半導体レーザを１：１に対応させて入力信
号により対応する半導体レーザを強度変調し、各半導体
レーザの出力光を光導波路により入力光に対する波長選
択性を有しない光ミキサーに導いて混合し、光ミキサー
の出力を１又は５ 複数の光ケーブルにより伝送し、受
信側では受信した光信号を波長選択性を有する素子によ
り、光信号の波長を選択することな＜光検波器により電
気信号に変換するごとき光ケーブル伝送方式にある。In this configuration, depending on the number of multiplexed channels (n) and the arrangement of carrier frequencies to be multiplexed, if we take the frequency arrangement of the VHF band used for normal commercial broadcasting in Japan as an example, channels 1 to 3 The low-band second-order harmonic distortion falls into the high-band band from channel 5 to channel 11, and the low-band and high-band secondary beads fall within each band/area, making the linearity imposed on the semiconductor laser very strict. Katsuta (Figure 2). Furthermore, the degree of modulation of light per channel becomes smaller, and due to internal noise of the semiconductor laser, the signal-to-noise ratio per channel shows saturation characteristics even if the received light level is increased, and the signal-to-noise ratio on the sending side decreases. However, it has disadvantages such as being unable to obtain a sufficient signal-to-noise ratio. The present invention aims to improve these drawbacks by driving a plurality of semiconductor lasers with television signals of different channels, and then distributing the signals to the receiving side using an optical mixer.
The input signal is a plurality of television signals or baseband television signals that are modulated with different carrier frequencies and set so that the spectra of the modulated waves do not overlap with each other, and each television input signal and the semiconductor laser are in a 1:1 correspondence. intensity modulates the corresponding semiconductor laser with the input signal, and guides the output light of each semiconductor laser through an optical waveguide to an optical mixer that does not have wavelength selectivity with respect to the input light and mixes it. It is an optical cable transmission method in which the received optical signal is transmitted by an optical cable, and on the receiving side, the received optical signal is converted into an electrical signal by a photodetector without selecting the wavelength of the optical signal.
以下図面により詳細に説明する。This will be explained in detail below with reference to the drawings.
第３図は本発明の実施例の１つでありｎ個の入力された
テレビ信号を互いに相異なりかつ被変調波が互いに重な
らないように設定された寄ヤリア周波数をもつ変調器２
１〜２ｎで各々変調しＲＦ変調されたテレビ信号で３１
〜３ｎの各々の半導体レーザを光源とする電気光変換器
で光信号に変換する。FIG. 3 shows one embodiment of the present invention, in which a modulator 2 has a modulator frequency set so that n input television signals are different from each other and the modulated waves do not overlap each other.
31 with RF modulated television signals modulated with 1 to 2n respectively.
~3n semiconductor lasers are converted into optical signals by electro-optical converters using each semiconductor laser as a light source.
光信号は８の光フアイバなどの導波路で７の光ミキサー
に接続される。光ミキサーに訃いて入力されたｎ個のテ
レビ信号は光領域で混合され多重化される。多重化され
た光信号は光ミキサー７の出力側から光伝送路４に取り
出され光検波器５１〜５ｍにおいて受信され増幅器６，
〜６ｍで所要のレベルに増幅されて電気出力としてとり
出されテレビ受像機などに接続される。本例では光ミキ
サーの出力数をｍとした。光ミキサーの具体的な構成例
については例えば、文献（ＥｌｅｃｔｒＯｎｉｃｓＬｅ
ｔｔｅｒｓｌ９８ＯＶＯｌｌ６，／Ｆ６．ｌ５，ｐｐ６
Ｏ８−６０９１Ｓ１ａｂＷａｖｅｇｕｉｄｅＳｔａｒＣ
０ｕｐ１ｅｒｆ０ｒＭｕ１ｔｉｍａｄｅ０ｐｔｉｃａ１
Ｆｉｂｒｅｓ″ＢｙＫ．ＮＯｓｕ，Ｒ．Ｗａｔａｎａｂ
ｅ）に詳しい。The optical signal is connected to an optical mixer at 7 by a waveguide such as an optical fiber at 8. The n television signals inputted to the optical mixer are mixed and multiplexed in the optical domain. The multiplexed optical signal is taken out from the output side of the optical mixer 7 to the optical transmission line 4, received by the optical detectors 51 to 5m, and then sent to the amplifiers 6,
It is amplified to the required level at ~6 m, taken out as electrical output, and connected to a television receiver or the like. In this example, the number of outputs of the optical mixer is m. For specific configuration examples of optical mixers, see the literature (ElectrOnicsLe
ttersl98OVOll6,/F6. l5, pp6
O8-6091S1abWaveguideStarC
0up1erf0rMu1timade0ptica1
Fibres″ByK. NOsu, R. Watanab
I am familiar with e).
この場合チヤンネル毎に光源が異なるので光源の非直線
性に起因する高調波ひずみは生じるが、第１図で示した
従来の例の様に２次ビードのような影響の大きな相互変
調ひずみは生じないので半導体レーザに課せられる直線
性は従来例ほど厳しくする必要はない。更に光源側に｝
いて半導体レーザ１個当りの変調度を高くとれるので送
り側に卦ける信号対雑音比は例えば８チヤンネル伝送を
例にとれば従来の例に比べて（２０ｔ０９８−）１８ｄ
Ｂ高くとれ、送り側の信号対雑音比による制限は従来例
によるものよりも１８ｄＢ高くなる。In this case, since the light source is different for each channel, harmonic distortion occurs due to the nonlinearity of the light source, but as in the conventional example shown in Figure 1, intermodulation distortion with a large effect such as secondary beads does not occur. Therefore, the linearity imposed on the semiconductor laser does not need to be as strict as in the conventional example. Further towards the light source}
Since the modulation degree per semiconductor laser can be high, the signal-to-noise ratio on the sending side is (20t098-)18d compared to the conventional example, for example, in 8-channel transmission.
The signal-to-noise ratio on the sending side is 18 dB higher than in the conventional example.
７チヤンネル伝送の場合の従来例ではチヤンネル当り変
調度が０．１とし３５〜４５ｄＢ程度が送り側で最大得
られる信号対雑音比（搬送波対雑音比Ｃｒｍｓ／Ｎｒｍ
ｓ）である。In the conventional case of 7-channel transmission, the modulation degree per channel is 0.1, and the signal-to-noise ratio (carrier-to-noise ratio Crms/Nrm) that can be obtained at the maximum on the sending side is about 35 to 45 dB.
s).
伝送路でＣ／Ｎが劣化するので、望ましい規格４２ｄＢ
を、フアイバ伝送した受信側で得ることは困難でありこ
のことが実用上の大きな障害となつていた。本実施例に
よれば送り側の信号対雑音比は５３〜６３ｄＢ程度とな
り送り側の信号対雑音比の制限は望ましい規格４２ｄＢ
に対して十分高く、受信品質の点で問題ない。また半導
体レーザを複数個用いているので仮に１個の半導体レー
ザが劣化した場合もそれに対応するチヤンネルが伝送さ
れないだけで他のチヤンネルはそのまま生きて卦り障害
が他チヤンネルにまで波及しないというメリツトがあり
信頼性の上からも有利である。Since the C/N deteriorates in the transmission path, the desired standard is 42 dB.
It is difficult to obtain this at the receiving end through fiber transmission, and this has been a major obstacle in practical use. According to this embodiment, the signal-to-noise ratio on the sending side is about 53 to 63 dB, and the limit on the signal-to-noise ratio on the sending side is the desired standard of 42 dB.
It is sufficiently high compared to the standard, and there is no problem in terms of reception quality. In addition, since multiple semiconductor lasers are used, even if one semiconductor laser deteriorates, the corresponding channel will not be transmitted, and the other channels will continue to operate as they are, which has the advantage that the failure will not spread to other channels. This is also advantageous in terms of reliability.
第４図は本発明の他の実施例の一であり、１つの半導体
レーザに複数チヤンネル（この例では２チヤンネル）の
周波数分割多重されたテレビ信号を割り当て複数個（こ
こではｎ個）の半導体レーザを用いて全部で２ｎチヤン
ネルのテレビ信号を伝送する構成をとつている。FIG. 4 shows another embodiment of the present invention, in which frequency division multiplexed television signals of multiple channels (2 channels in this example) are assigned to one semiconductor laser, and multiple (n in this example) semiconductor lasers are used. The structure is such that a total of 2n channels of television signals are transmitted using lasers.
本実施例によれば例えば８チヤンネル伝送を例にとれば
前記実施例の半分の４個の半導体レーザですむ利点があ
る。この場合、従来の実施例に比べて送信側の信号対雑
音比の改善量は（２０ｔ０９４）−１２ｄＢとなり実質
土支障のない値が得られる。第５図は本発明の他の実施
例であつて１１はテレビ放送を受信するためのアンテナ
、１０は各チヤンネル毎に受信、増幅するヘツドエンド
増幅器である。According to this embodiment, for example, in the case of 8-channel transmission, there is an advantage that only four semiconductor lasers are required, which is half of that of the previous embodiment. In this case, compared to the conventional embodiment, the amount of improvement in the signal-to-noise ratio on the transmitting side is (20t094)-12 dB, which is a value with virtually no interference. FIG. 5 shows another embodiment of the present invention, in which 11 is an antenna for receiving television broadcasting, and 10 is a head-end amplifier for receiving and amplifying each channel.
１０からの出力をチヤンネルごとに光送信器３１〜３ｎ
に接続し光信号に変換する。10 to optical transmitters 31 to 3n for each channel.
and convert it into an optical signal.
本実施例によれば最初の実施例で述べた利点以外に放送
テレビ信号をそのまま増幅分離するだけで直接光増幅器
に接続できるのでＲＦ変調器等が必要なく構成が簡単に
なる利点がある。以上の３つの実施例においてハイバン
ド用の半導体レーザは２次ひずみ特性が悪いものを用い
てもよいがローバンド用のもののうち２次高調波がハイ
バンド帯域内に落ち込むチヤンネル用の半導体レーザは
２次ひずみ特性が良いものを用いる必要がある。According to this embodiment, in addition to the advantages mentioned in the first embodiment, there is an advantage that the broadcast television signal can be directly connected to an optical amplifier by simply amplifying and separating it, so that an RF modulator or the like is not required and the configuration can be simplified. In the above three embodiments, semiconductor lasers for high bands with poor secondary distortion characteristics may be used, but semiconductor lasers for channels where the second harmonic falls within the high band band among those for low bands are It is necessary to use a material with good order strain characteristics.
更に第１，第２の実施例に訃いて周波数配置を第６図の
如くローバンドの２次高調波が・・イバンドの帯域外に
落ち込むように設定すればローパットに用いる半導体レ
ーザは２次ひずみ特性が悪くてもハイバンドに影響を与
えないので２次ひずみの非直線性が悪いグレードの低い
半導体レーザを用いることができる利点がある。Furthermore, if the frequency arrangement is set in accordance with the first and second embodiments so that the second harmonic of the low band falls outside the I band as shown in Fig. 6, the semiconductor laser used for the low putt will have a second order distortion characteristic. Even if the distortion is bad, it does not affect the high band, so there is an advantage that a low grade semiconductor laser with poor second-order distortion nonlinearity can be used.
以上説明したように従来得られなかつた大きな信号対雑
音比が得られ、しかも直線性が比較的よくない半導体レ
ーザを用いることができ信頼性にすぐれるなどの利点が
あり、光フアイバを用いるＣＡＴＶシステムあるいはＴ
Ｖ放送システムに訃いて特に有用である。As explained above, CATV using optical fiber has the advantage of being able to obtain a large signal-to-noise ratio that could not be obtained in the past, and also being able to use semiconductor lasers with relatively poor linearity and excellent reliability. system or T
This is particularly useful for V broadcast systems.
更に高出力半導体レーザを用いれは従来の形式では１加
入当り１個の光源が必要であつたが、本発明によれば光
ミキサーの出力端子を増すことによつて半導体レーザの
出力レベルにより１加入当りに必要な半導体レーザの個
数は０．１個以下にすることも可能で実質上極めて有用
である。Furthermore, when using a high-output semiconductor laser, one light source was required for each input in the conventional format, but according to the present invention, by increasing the output terminal of the optical mixer, the output level of the semiconductor laser can be increased to one input. The number of semiconductor lasers required per unit can be reduced to 0.1 or less, which is extremely useful.
第１図は従来のＦＤＭ多重されたテレピ信号の光伝送方
式の構成図、第２図は日本のテレビ放送の周波数配置を
示す図、第３図は本発明による光伝送方式を示す図、第
４図は本発明による別の光伝送方式を示す図、第５図は
本発明による更に別の光伝送方式を示す図、第６図はＦ
ＤＭ多重信号の周波数帯域を２群にした時のローバンド
の高調波が・・イバンドの帯域外に落ち込む様に設定し
た周波数配置の概念図である。
１・・・ＦＤＭ多重化装置、２・・・ＲＦ変調器、３・
・・光送信器、４・・・光フアイバケーブル、５・・・
光検波器、６・・・増幅器、７・・・光ミキサー、８・
・・光ミキサー入力用光フアイバ又は光導波路、９・−
・ＲＦ変調ＦＤＭ多重化装置、１０・・・ヘツドエンド
増幅器、１１・・・受信用アンテナ。Fig. 1 is a block diagram of a conventional optical transmission system for FDM multiplexed television signals, Fig. 2 is a diagram showing the frequency allocation of Japanese television broadcasting, and Fig. 3 is a diagram showing an optical transmission system according to the present invention. 4 is a diagram showing another optical transmission method according to the present invention, FIG. 5 is a diagram showing still another optical transmission method according to the present invention, and FIG. 6 is a diagram showing another optical transmission method according to the present invention.
It is a conceptual diagram of a frequency arrangement set so that the harmonics of the low band fall outside the band of the i-band when the frequency band of the DM multiplex signal is divided into two groups. DESCRIPTION OF SYMBOLS 1... FDM multiplexer, 2... RF modulator, 3...
... Optical transmitter, 4... Optical fiber cable, 5...
Optical detector, 6... Amplifier, 7... Optical mixer, 8.
・・Optical fiber or optical waveguide for optical mixer input, 9・−
- RF modulation FDM multiplexing device, 10...head end amplifier, 11... receiving antenna.
Claims (1)
トルが相互に重ならない様に設定された複数のテレビ信
号又はベースバンドテレビ信号を入力信号とし、各テレ
ビ入力信号と半導体レーザを１：１に対応させて入力信
号により対応する半導体レーザを強度変調し、各半導体
レーザの出力光を光導波路により入力光に対する波長選
択性を有しない光ミキサーに導いて混合し、光ミキサー
の出力を１又は複数の光ケーブルにより伝送し、受信側
では受信した光信号を波長選択性を有する素子により、
光信号の波長を選択することなく光検波器により電気信
号に変換することを特徴とする光ケーブル伝送方式。1 Input multiple television signals or baseband television signals that are modulated with different carrier frequencies and set so that the spectra of the modulated waves do not overlap with each other, and make each television input signal and semiconductor laser correspond 1:1. intensity modulates the corresponding semiconductor laser with the input signal, guides the output light of each semiconductor laser through an optical waveguide to an optical mixer that does not have wavelength selectivity with respect to the input light, and mixes it, and connects the output of the optical mixer to one or more optical cables. On the receiving side, the received optical signal is transmitted by a wavelength-selective element.
An optical cable transmission method that uses a photodetector to convert optical signals into electrical signals without selecting the wavelength of the optical signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56037277A JPS5928098B2 (en) | 1981-03-17 | 1981-03-17 | Optical cable transmission method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56037277A JPS5928098B2 (en) | 1981-03-17 | 1981-03-17 | Optical cable transmission method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57152739A JPS57152739A (en) | 1982-09-21 |
| JPS5928098B2 true JPS5928098B2 (en) | 1984-07-10 |
Family
ID=12493186
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP56037277A Expired JPS5928098B2 (en) | 1981-03-17 | 1981-03-17 | Optical cable transmission method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5928098B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63148724A (en) * | 1986-12-12 | 1988-06-21 | Kandenko Co Ltd | Television image signal multiplex transmission method in catv system |
| US4832433A (en) * | 1986-12-31 | 1989-05-23 | Hughes Aircraft Company | Fiber-optic feed network using series/parallel connected light emitting opto-electronic components |
| EP0790717B1 (en) * | 1996-02-16 | 2006-06-14 | Robert Bosch Gmbh | Device for transmittimg several received broadband radio signals to a signal receiver and signal receiver therefor |
-
1981
- 1981-03-17 JP JP56037277A patent/JPS5928098B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57152739A (en) | 1982-09-21 |
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