JPH03132227A - Rf multiple signal light transmission system - Google Patents
Rf multiple signal light transmission systemInfo
- Publication number
- JPH03132227A JPH03132227A JP1270650A JP27065089A JPH03132227A JP H03132227 A JPH03132227 A JP H03132227A JP 1270650 A JP1270650 A JP 1270650A JP 27065089 A JP27065089 A JP 27065089A JP H03132227 A JPH03132227 A JP H03132227A
- Authority
- JP
- Japan
- Prior art keywords
- video signals
- signal
- channels
- analog
- multiplexed
- 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
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- 230000005540 biological transmission Effects 0.000 title claims description 20
- 230000003287 optical effect Effects 0.000 claims abstract description 27
- 239000004065 semiconductor Substances 0.000 claims abstract description 19
- 238000000034 method Methods 0.000 claims description 5
- 230000001934 delay Effects 0.000 claims 1
- 230000006866 deterioration Effects 0.000 abstract description 5
- 239000013307 optical fiber Substances 0.000 abstract description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000002123 temporal effect Effects 0.000 description 3
- 208000019300 CLIPPERS Diseases 0.000 description 1
- 244000025254 Cannabis sativa Species 0.000 description 1
- 235000012766 Cannabis sativa ssp. sativa var. sativa Nutrition 0.000 description 1
- 235000012765 Cannabis sativa ssp. sativa var. spontanea Nutrition 0.000 description 1
- 235000009120 camo Nutrition 0.000 description 1
- 235000005607 chanvre indien Nutrition 0.000 description 1
- 208000021930 chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids Diseases 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 239000011487 hemp Substances 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
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Abstract
Description
【発明の詳細な説明】
産業上の利用分野
本発明（友 光伝送の分野において、多チャンネルの映
像信号をアナログ周波数多重し半導体レーザを用いて光
強度変調により伝送するＲＦＦ重信号光伝送方式に関す
るものであも
従来の技術
従来のＲＦＦ重信号光伝送方式において、複数の映像信
号をアナログ周波数多重し半導体レーザを用いて伝送す
る場色 半導体レーザの変調度により雑音の発生の様子
や信号の高調波歪み量が変動することが知られていも
特に過変調になると雑音や歪み特性力（著しく劣化すム
そこで伝送するチャンネル数Ｎに応じて、総合変調度が
過変調にならないように各チャンネル当たりの変調度ｍ
を決めてい丸 しかし最近 多重する映像信号のチャン
ネル数を増加させてｋ 必ずしも過変調にならないこと
が明らかとなってきた つまり各映像信号間の信号振幅
に時間的に相関が無い場合の総合変調度；よ 各チャン
ネルの変調度の単純加算（Ｎ ｘ ｍ）にはならｆ、ｍ
ＪＮで近似できることが実験により確認されて・きたた
めであも
そこで総合変調度をｍＪＮで近似し 多チャンネルの多
重が行われるようになりつつあ本発明が解決しようとす
る課題
しかしながら上記の多重伝送方式で（友 多重する各映
像信号間の信号振幅に時間的に相関がある場合にζよ
総合変調度が大きくなり過変調になる恐れがあム また
多重する各映像信号間に時間的に相関が無い場合でも瞬
間的に過変調になることは避けられな（〜 そのときに
（友 半導体レーザの雑音や歪み特性が著しく変化し伝
送画質の劣化を招くことになも
本発明はかかる点に鑑へ 半導体レーザの過変調による
影響を軽減し伝送画質の安定化を図ったＲＦ多重信号光
伝送方式を提供することを目的とすａ
課題を解決するための手段
（第１の手段）
本発明のＲＦ多重信号光伝送方式（友 上記課題を解決
するためく 多重するＮチャンネルの映像信号のうちＮ
／２チャンネルの映像信号の極性を反転しアナログ周波
数多重するものであａ（第２の手段）
本発明のＲＦ多重信号光伝送方式（友 上記課題を解決
するため番ζ アナログ周波数多重信号の振幅を検出し
基準値をこえる多重信号の信号振幅部分をクリップし
半導体レーザを変調するものであも
（第３の手段）
本発明のＲＦ多重信号光伝送方式（友 上記課題を解決
するため番ζ アナログ周波数多重信号の振幅を基準値
と比較する比較部と、比較部の出力に応じ多重する映像
信号を遅延させる遅延部を設はアナログ周波数多重し
半導体レーザを変調するものであ４
作用
上記手段により、半導体レーザが過変調となることを抑
圧し伝送画質の安定化を図ることができも
実施例
本発明の実施例を図面とともに説明す翫（実施例１）
第１図は本発明の第１の実施例であるＲＦ多重信号光伝
送装置の構成を示すブロック図であも第１図においてｌ
はアナログ反転アンプ、２は周波数多重部 ３は半導体
レーザを用いた光送信部 ４は光ファイベ ５は受光素
子を用いた光受信ａ ６はチューナであａ
奇数チャンネルの映像信号はそのまま周波数多重部２に
入力され 偶数チャンネルの映像信号はアナログ反転ア
ンプｌによりその極性が反転されたのち周波数多重部２
に入力されも 周波数多重部２からはアナログ周波数多
重された信号が光送信部３に加えられも 光送信部３で
（上 アナログ周波数多重信号により半導体レーザが変
調されその光信号が光ファイバ４に送られも
光受信部５で（上 受信した光信号を電気信号に変換し
チューナ６に送も そしてチューナ６から出力される偶
数チャンネルの映像信号４上 アナログ反転アンプｌに
より再びその極性が反転され元の極性にもどされも
周波数多重部２において、各映像信号は搬送波を振幅変
調すも このとき映像信号の水平同期部で搬送波の振幅
が最大となも そこで、偶数チャンネルの映像信号の極
性をアナログ反転アンプｌにより反転させることにより
、すべての映像信号の位相が同期するような場合でＬ
映像信号の水平同期部の極性が交互に加算されることに
なりアナログ周波数多重された信号の信号振幅は平均化
されることになも さら番ζ 送信側の各アナログ反転
アンプ１に遅延時間をもたせれば アナログ周波数多重
信号の信号振幅は一層平均化されることになａ
（実施例２）
第２図は本発明の第２の実施例であるＲＦ多重信号光伝
送装置の構成を示すブロック図であａ砥 第２図におい
て第１図と同等の機能作用を有するものには第１図と同
一の番号を付し 詳細な説明は略す。Detailed Description of the Invention The present invention relates to an RFF multiple signal optical transmission system in which multi-channel video signals are analog frequency multiplexed and transmitted by optical intensity modulation using a semiconductor laser. Conventional technology In the conventional RFF multiple signal optical transmission method, multiple video signals are analog frequency multiplexed and transmitted using a semiconductor laser. Although it is known that the amount of wave distortion fluctuates,
In particular, when overmodulation occurs, noise and distortion characteristics (remarkably deteriorate)
However, recently it has become clear that increasing the number of multiplexed video signal channels does not necessarily result in overmodulation.In other words, it has become clear that overmodulation does not necessarily occur when the signal amplitudes of each video signal have no temporal correlation. ;Yo, for a simple addition (N x m) of the modulation degree of each channel, f, m
Since it has been confirmed through experiments that it can be approximated by JN, the overall modulation depth is approximated by mJN.As multi-channel multiplexing is being carried out, the problem that the present invention aims to solve.However, the above-mentioned multiplex transmission (Tomo) When there is a temporal correlation in the signal amplitude between the video signals to be multiplexed, ζ
There is a risk of overmodulation as the total modulation degree increases.Also, even if there is no temporal correlation between multiplexed video signals, instantaneous overmodulation is unavoidable. In view of the fact that the noise and distortion characteristics of lasers change significantly, leading to deterioration of transmission image quality, the present invention has been developed to provide an RF multiplexed signal light that reduces the influence of overmodulation of semiconductor lasers and stabilizes transmission image quality. A means for solving the problem (first means) RF multiplexed signal optical transmission system of the present invention Of which N
A (Second means) RF multiplexed signal optical transmission system of the present invention (Part 2) In order to solve the above problems, the amplitude of the analog frequency multiplexed signal is is detected and clips the signal amplitude part of the multiplexed signal that exceeds the reference value.
A method for modulating a semiconductor laser (third means) RF multiplexed signal optical transmission system of the present invention (a third means) A delay section is installed to delay the video signal to be multiplexed according to the output of the comparator section for analog frequency multiplexing.
It modulates a semiconductor laser. 4. Effect: By the above means, overmodulation of the semiconductor laser can be suppressed and the transmission image quality can be stabilized. Embodiment 1) FIG. 1 is a block diagram showing the configuration of an RF multiplexed signal optical transmission apparatus which is a first embodiment of the present invention.
is an analog inverting amplifier, 2 is a frequency multiplexing section, 3 is an optical transmitting section using a semiconductor laser, 4 is an optical fiber, 5 is an optical receiving section using a light receiving element, 6 is a tuner a, and the odd channel video signal is sent directly to the frequency multiplexing section. The even-numbered channel video signals are input to frequency multiplexer 2 after having their polarities inverted by analog inverting amplifier l.
The analog frequency multiplexed signal from the frequency multiplexing section 2 is applied to the optical transmitting section 3.The optical transmitting section 3 modulates the semiconductor laser with the analog frequency multiplexed signal, and the optical signal is sent to the optical fiber 4. The received optical signal is converted into an electrical signal and sent to the tuner 6 by the optical receiver 5 (above), and the even channel video signal 4 output from the tuner 6 is again inverted in polarity by the analog inverting amplifier l. Even if the original polarity is restored, the frequency multiplexer 2 modulates the amplitude of the carrier wave for each video signal. At this time, the amplitude of the carrier wave is maximum in the horizontal synchronization part of the video signal. L is used in cases where the phases of all video signals are synchronized by inversion using an analog inverting amplifier L.
Since the polarities of the horizontal synchronization part of the video signal are added alternately, the signal amplitude of the analog frequency multiplexed signal is averaged. If this is done, the signal amplitude of the analog frequency multiplexed signal will be further averaged.a (Embodiment 2) Fig. 2 is a block diagram showing the configuration of an RF multiplexed signal optical transmission apparatus according to the second embodiment of the present invention. In FIG. 2, the same numbers as in FIG. 1 are given to parts having the same functions and effects as in FIG. 1, and detailed explanations are omitted.
第２図において、 ７はクリッパであり、周波数多重部
２から出力されるアナログ周波数多重信号の信号振幅を
予め設定した基準値と比較し その基準値をこえる信号
部分をクリップして光送信部３に送も 光送信部３では
クリップされたアナログ周波数多重信号により半導体レ
ーザが変調されも 基準値はこの半導体レーザの変調度
が過変調にならない範囲で設定されていも
従って、アナログ周波数多重信号の一部戟 ある瞬間に
はクリップされることがあるのて そのクリップ期間の
伝送画質の劣化は避けられな（〜しかし 半導体レーザ
が過変調になることはないの六 半導体レーザの雑音や
歪み特性の変動は避けら札 クリップ期間のみの画質劣
化に抑えられ（実施例３）
第３図は本発明の第３の実施例であるＲＦ多重信号光伝
送装置の構成を示すブロック図であａ殊 第３図におい
て第１図と同等の機能作用を有するものには第１図と同
一の番号を付し 詳細な説明は略す。In FIG. 2, 7 is a clipper which compares the signal amplitude of the analog frequency multiplexed signal output from the frequency multiplexing section 2 with a preset reference value, clips the signal portion exceeding the reference value, and transmits the signal amplitude to the optical transmitter 3. Even if the semiconductor laser is modulated by the clipped analog frequency multiplexed signal in the optical transmitter 3, the reference value is set within a range in which the modulation degree of this semiconductor laser does not become overmodulated. Because clipping may occur at a certain moment, deterioration of the transmitted image quality during that clipping period is unavoidable. Image quality deterioration is suppressed only during the clipping period (Embodiment 3) FIG. In the figure, parts having the same functions and actions as those in FIG. 1 are given the same numbers as in FIG. 1, and detailed explanations are omitted.
第３図において、 ８は比較部 ９はＴＶ変調器１００
＋ｋ（ｋは整数 １≦に≦Ｎ）は遅延部２はＴＶ変調器
９と遅延部（１００＋ｋ）とからなる周波数多重部であ
も
周波数多重部２からのアナログ周波数多重信号は比較部
８に入力されも 比較部８で（友 アナログ周波数多重
信号の信号振幅を基準値と比較し基準値をこえる場合が
生じると比較部２Ｈ＆に個の遅延部（１００＋ｋ）に制
御信号を送も この基準値（友 半導体レーザの変調度
が過変調にならない範囲で設定されており、アナログ周
波数多重信号の信号振幅バ これをこえるとき遅延部（
１００＋ｋ）に制御信号を送ることになも 各遅延部（
１００＋ｋ）はその制御信号により、各遅延部（１００
＋ｋ）に入力されている変調された搬送波を設定された
時間遅延すム
−４制御信号を受けると遅延時間を保持し電源がきれる
までリセットされな−また 各遅延部（１００＋ｋ）に
よる遅延時間（上 互いに異なる値に設定されていも
このような構成により、各チャンネルの搬送波の位相が
一致してアナログ周波数多重信号の信号振幅戟 半導体
レーザの過変調を招くまでに大きくなることがあってｋ
比較部８により検出されいくつかのチャンネルの映像
信号にそれぞれ異なる遅延時間が与えられるたべ 光送
信部３の半導体レーザに加えられるアナログ周波数多重
信号の振幅は平均化されることになも
発明の効果
本発明によれ４４ 半導体レーザの過変調による伝送
画質の劣化を軽減し 多チャンネルの映像信号を伝送で
きるためその経済的効果は多大であムIn FIG. 3, 8 is a comparison section 9 is a TV modulator 100
+k (k is an integer, 1≦≦N) means that the delay section 2 is a frequency multiplexing section consisting of a TV modulator 9 and a delay section (100+k), and the analog frequency multiplexed signal from the frequency multiplexing section 2 is sent to the comparison section 8. Even if the signal amplitude of the analog frequency multiplexed signal is inputted, the comparator 8 compares the signal amplitude of the analog frequency multiplexed signal with a reference value, and if the signal amplitude exceeds the reference value, it sends a control signal to the delay unit (100+k) in the comparator 2H&. (Friend: The modulation degree of the semiconductor laser is set within a range that does not cause overmodulation, and when the signal amplitude of the analog frequency multiplexed signal exceeds this range, the delay part (
There is no need to send control signals to each delay section (100+k).
100+k) is connected to each delay section (100+k) by its control signal.
+k) The modulated carrier wave input to the delay unit (100+k) is delayed by a set time.When a control signal is received, the delay time is held and is not reset until the power is turned off. Even if they are set to different values, with this configuration, the phase of the carrier waves of each channel will match, and the signal amplitude of the analog frequency multiplexed signal may become large enough to cause overmodulation of the semiconductor laser.
The advantage of the invention is that the amplitudes of the analog frequency multiplexed signals applied to the semiconductor laser of the optical transmitter 3 are averaged since different delay times are given to the video signals of several channels detected by the comparator 8. According to the present invention, the deterioration in transmission image quality due to overmodulation of semiconductor lasers can be reduced and multi-channel video signals can be transmitted, so the economic effects are enormous.
第１皿 第２阻 第３図は本発明における各実施例のＲ
Ｆ多重信号光伝送方式の構成を示すブロック図であ翫
１・・・アナログ反転アン″’７２・・・周波数多重部
３・・・光送信部 ４・・・光ファイベ５・・・光受
信ａ ６・・・チューナ、７・・クリソｔ＜ ８・・
・比較ａ ９・・・ＴＶ変調麻１００＋ｋ・・・遅延部1st dish 2nd dish Figure 3 shows R of each embodiment of the present invention.
This is a block diagram showing the configuration of the F multiplexed signal optical transmission system. a 6...tuner, 7...chryso t< 8...
・Comparison a 9...TV modulation hemp 100+k...delay part
Claims (3)
アナログ周波数多重し半導体レーザを光源として用いア
ナログ光伝送する方式において、多重する映像信号のう
ちＮ／２チャンネルの映像信号の極性を反転しアナログ
周波数多重することを特徴とするＲＦ多重信号光伝送方
式。(1) In a method of analog frequency multiplexing of video signals of N channels (N is an integer, 1<N) and analog optical transmission using a semiconductor laser as a light source, the polarity of video signals of N/2 channels of the multiplexed video signals An RF multiplex signal optical transmission system characterized by inverting and multiplexing analog frequencies.
アナログ周波数多重し半導体レーザを光源として用いア
ナログ光伝送する方式において、アナログ周波数多重信
号の振幅を検出し予め設定された基準値をこえる信号振
幅部分をクリップする手段を設けたことを特徴とするＲ
Ｆ多重信号光伝送方式。(2) In a method in which video signals of N channels (N is an integer, 1<N) are analog frequency multiplexed and a semiconductor laser is used as a light source for analog optical transmission, the amplitude of the analog frequency multiplexed signal is detected and a preset reference value is used. R characterized in that it is provided with means for clipping a signal amplitude portion exceeding .
F multiplexed signal optical transmission system.
アナログ周波数多重し半導体レーザを光源として用いア
ナログ光伝送する方式において、アナログ周波数多重信
号の振幅を予め設定された基準値と比較する比較部と、
比較部の出力により前記Ｎチャンネルの映像信号を遅延
する遅延部とを設けたことを特徴とするＲＦ多重信号光
伝送方式。(3) Comparing the amplitude of the analog frequency multiplexed signal with a preset reference value in a method in which video signals of N channels (N is an integer, 1<N) are analog frequency multiplexed and a semiconductor laser is used as a light source for analog optical transmission. A comparison section to
An RF multiplexed signal optical transmission system, further comprising a delay section that delays the N-channel video signal based on the output of the comparison section.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1270650A JPH03132227A (en) | 1989-10-18 | 1989-10-18 | Rf multiple signal light transmission system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1270650A JPH03132227A (en) | 1989-10-18 | 1989-10-18 | Rf multiple signal light transmission system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH03132227A true JPH03132227A (en) | 1991-06-05 |
Family
ID=17489048
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1270650A Pending JPH03132227A (en) | 1989-10-18 | 1989-10-18 | Rf multiple signal light transmission system |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH03132227A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05206952A (en) * | 1991-08-15 | 1993-08-13 | General Instr Corp | Low-distortion laser system for amplitude- modulated optical fiber communication use |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54134904A (en) * | 1978-04-12 | 1979-10-19 | Matsushita Electric Ind Co Ltd | Light transmission system |
| JPS56132031A (en) * | 1980-03-19 | 1981-10-16 | Hitachi Denshi Ltd | Telephone transmission system |
| JPS60130233A (en) * | 1983-12-16 | 1985-07-11 | Matsushita Electric Ind Co Ltd | Fdm signal optical transmitter |
| JPS63177636A (en) * | 1987-01-19 | 1988-07-21 | Toshiba Corp | In-band tone transmitting system |
-
1989
- 1989-10-18 JP JP1270650A patent/JPH03132227A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54134904A (en) * | 1978-04-12 | 1979-10-19 | Matsushita Electric Ind Co Ltd | Light transmission system |
| JPS56132031A (en) * | 1980-03-19 | 1981-10-16 | Hitachi Denshi Ltd | Telephone transmission system |
| JPS60130233A (en) * | 1983-12-16 | 1985-07-11 | Matsushita Electric Ind Co Ltd | Fdm signal optical transmitter |
| JPS63177636A (en) * | 1987-01-19 | 1988-07-21 | Toshiba Corp | In-band tone transmitting system |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05206952A (en) * | 1991-08-15 | 1993-08-13 | General Instr Corp | Low-distortion laser system for amplitude- modulated optical fiber communication use |
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