JPH03283928A - Pfm optical transmission system - Google Patents
Pfm optical transmission systemInfo
- Publication number
- JPH03283928A JPH03283928A JP2084105A JP8410590A JPH03283928A JP H03283928 A JPH03283928 A JP H03283928A JP 2084105 A JP2084105 A JP 2084105A JP 8410590 A JP8410590 A JP 8410590A JP H03283928 A JPH03283928 A JP H03283928A
- Authority
- JP
- Japan
- Prior art keywords
- output
- signal
- modulator
- circuit
- pfm
- 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
Links
- 230000005540 biological transmission Effects 0.000 title claims abstract description 14
- 230000003287 optical effect Effects 0.000 title claims description 10
- 230000005236 sound signal Effects 0.000 abstract description 3
- 238000000034 method Methods 0.000 description 4
- 230000003321 amplification Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 239000002131 composite material Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明はＰＦＭ光伝光伝送方間し、特にＣＡＴＶなどの
分野でユーザがリクエストした時だけ映像及び音−のサ
ービスを受けることが出き、それ以外はサービスを受け
られないようにする有料サービスに用いるスクランブラ
機能付のＰＦＭ光伝送方式に関する。[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a PFM optical transmission system, particularly in the field of CATV, etc., where video and audio services can be received only when requested by the user. , relates to a PFM optical transmission system with a scrambler function used for paid services that prevent other services from being received.
従来、この種のＰＦＭ光伝光伝送方間けるスクランブラ
方式としては、送ｋｍ又は受信側において映倫信号の極
性を反転させる（通常は同期信号が負側であるかが正側
に反転させる）方式が一般的である。こうすることによ
り、通常の受像機には同期がかからず映像として復元で
きない。しかし、音声まではスクランブルがかからず聞
くことができるというものである。Conventionally, as a scrambler method for this type of PFM optical transmission, the polarity of the Eirin signal is reversed on the transmitting km or receiving side (usually, the synchronization signal is reversed from negative to positive). This method is common. By doing this, normal television receivers cannot synchronize and restore the video. However, the audio can be heard without being scrambled.
上述した従来のＰＦＭ光伝送方式は、ただ単に映像信号
の極性を反転させてスクランブルをカーけるものである
ため、ユーザ側で伝送装置と受信機との間に反転増幅器
を挿入することにより映像を復元することができる。更
に、音声信号については全くスクランブルがかからず、
無料で開けてしまうという欠点がある。The conventional PFM optical transmission method described above simply inverts the polarity of the video signal to eliminate scrambling. Can be restored. Furthermore, the audio signal is not scrambled at all,
The downside is that you can open it for free.
このような理由で、従来のＰＦＭ光伝送方式はスクラン
ブルの確実性という面で十分とは言えない欠点がある。For these reasons, the conventional PFM optical transmission system has a drawback in that scrambling reliability is not sufficient.
本発明の目的は、確実なスクランブル機能を簡単な構成
で実現できるＰＦＭ光伝送方式を提供することくある。An object of the present invention is to provide a PFM optical transmission system that can realize a reliable scrambling function with a simple configuration.
本発明のＰＦＭ光伝送方式は、繰返し周波数が入力信号
レベルに比例し平均値が一定であるパルス信号を出力す
るＳＷ−ＦＭｆ調器と、このＳＷ−ＦＭｆ調器からの前
記パルス信号を入力するモノマルチ回路と、このモノマ
ルチ回路又は前記ＳＷ−ＦＭ変調器のいずれか−１の出
力を選択する選択回路と、この選択回路の出力により駆
動される発光素子とを送信側に備え、受光素子と、この
受光素子からの信号を入力する増幅回路と、この増幅回
路からの信号をしきい値識別する比較器と、この比較器
力１らの信号を入力する低域通過沖波器とを受信側忙備
えている。The PFM optical transmission system of the present invention includes an SW-FMf modulator that outputs a pulse signal whose repetition frequency is proportional to the input signal level and whose average value is constant, and the pulse signal from the SW-FMf modulator is input. The transmitting side includes a mono multi circuit, a selection circuit for selecting the output of either the mono multi circuit or the SW-FM modulator, and a light emitting element driven by the output of the selection circuit, and a light receiving element. , an amplifier circuit that inputs the signal from this light-receiving element, a comparator that identifies the signal from this amplifier circuit with a threshold value, and a low-pass transducer that inputs the signals from this comparator. The side is busy.
次に、本発明について図面を参照して説明する。 Next, the present invention will be explained with reference to the drawings.
第１図は本発明の一実施例のブロック図である。FIG. 1 is a block diagram of one embodiment of the present invention.
第１図において、１は入力増幅回路であり映像及び音声
の複合信号を増幅する。２はＳＷ−ＦＭ変調器で、入力
増幅回路１の出力をＳＷ−ＦＭパルス信号（パルスの繰
り返し周波数が入力信号レベルに比例し平均値は常に一
定）Ｋ変換する。３はモノマルチ回路であり、ＳＷ−Ｆ
Ｍ変調器２が出力したＳＷ−ＦＭｍ号のパルス扁だけを
一定に変換する。４は選択回路で、無料サービスに対し
てはモノマルチ回路３の出力を選択し、有料サービスに
対してはリクエストがない限りＳＷ−ＦＭ変調器２の出
力を選択するようにする。５は発光素子駆動回路、６は
発光素子駆動回路５によって駆動される発光素子である
。In FIG. 1, numeral 1 denotes an input amplification circuit that amplifies a composite signal of video and audio. 2 is an SW-FM modulator which converts the output of the input amplifier circuit 1 into an SW-FM pulse signal (the pulse repetition frequency is proportional to the input signal level and the average value is always constant). 3 is a mono multi circuit, SW-F
Only the pulse width of the SW-FMm output from the M modulator 2 is converted to a constant value. 4 is a selection circuit which selects the output of the monomulti circuit 3 for free services, and selects the output of the SW-FM modulator 2 for paid services unless there is a request. 5 is a light emitting element drive circuit; 6 is a light emitting element driven by the light emitting element drive circuit 5;
以上が送信側であり、受信側では、７は受光素子で微弱
な光信号を電気信号に変換し、８の受信増幅回路で一定
レベルまで増幅する。９は比較器で、受信増幅回路８の
出力の半値を識別し一定撮幅のパルスに再生する。１０
は低域通過沖波器、１１は出力増幅回路である。低域通
過沖波器１０及び出力増幅回路１１は、送信側でモノマ
ルチ回路３を経由したＰＦＭ信号以外は復調できず（Ｓ
Ｗ−ＦＭ変ｖＩ４器２の出力は平均値が一定）サービス
な受けられないことになる。The above is the transmitting side, and on the receiving side, a light receiving element 7 converts a weak optical signal into an electrical signal, and a receiving amplification circuit 8 amplifies it to a certain level. A comparator 9 identifies the half value of the output of the reception amplifier circuit 8 and reproduces it into a pulse with a constant imaging width. 10
1 is a low-pass wave transducer, and 11 is an output amplifier circuit. The low-pass transducer 10 and the output amplifier circuit 11 cannot demodulate signals other than the PFM signal that has passed through the mono multi-circuit 3 on the transmitting side (S
(The average value of the output of the W-FM converter 2 is constant) This means that the service cannot be received.
以上説明したように本発明は、ＰＦＭ伝送方式の送信側
でＳＷ−ＦＭ変調器の出力をモノマルチ回路を通すか通
さないかで受信側で復調できるができないかが決定され
る。しかも、送信側でモノマルチ回路を通さない場合は
、送信信号の平均値が一定であるため、モノマルチ機能
を有さない受信側では映像信号も音声信号も全く復調す
ることが出きないため、従来の映像信号の極性を反転さ
せる方式に比べ確実であるばかりでなく、映像と音声の
両方を同時にモニタできないようにすることができる。As explained above, in the present invention, whether the output of the SW-FM modulator is passed through a monomulticircuit on the transmitting side of the PFM transmission system or not is determined whether it can be demodulated on the receiving side or not. Moreover, if the transmission side does not pass the mono multi circuit, the average value of the transmitted signal is constant, so the receiving side, which does not have the mono multi function, cannot demodulate the video signal or audio signal at all. This method is not only more reliable than the conventional method of reversing the polarity of the video signal, but also makes it possible to prevent both video and audio from being monitored at the same time.
第１図は本発明の一実施例のブロック図である。
２・・・・・・ＳＷ−ＦＭｆ：調器、３・・・・・・モ
ノマルチ回路、４・・・・・・選択回路、６・・・・・
・発光素子、７・・・・−・受光素子、８・・・・・受
信増幅回路、９・−・・・・比較器、１０・−・・・・
低域Ｆ波器。FIG. 1 is a block diagram of one embodiment of the present invention. 2...SW-FMf: Adjustment, 3...Mono multi circuit, 4...Selection circuit, 6...
・Light emitting element, 7... Light receiving element, 8... Receiving amplifier circuit, 9... Comparator, 10...
Low frequency F wave device.
Claims (1)
あるパルス信号を出力するＳＷ−ＦＷ変調器と、このＳ
Ｗ−ＦＭ変調器からの前記パルス信号を入力するモノマ
ルチ回路と、このモノマルチ回路又は前記ＳＷ−ＦＭ変
調器のいずれか一方の出力を選択する選択回路と、この
選択回路の出力により駆動される発光素子とを送信側に
備え、受光素子と、この受光素子からの信号を入力する
増幅回路と、この増幅回路からの信号をしきい値識別す
る比較器と、この比較器からの信号を入力する低域通過
ろ波器とを受信側に備えたことを特徴とするＰＦＭ光伝
送方式。An SW-FW modulator that outputs a pulse signal whose repetition frequency is proportional to the input signal level and whose average value is constant;
a monomulti circuit that inputs the pulse signal from the W-FM modulator; a selection circuit that selects the output of either the monomulticircuit or the SW-FM modulator; and a selection circuit that is driven by the output of the selection circuit. The transmission side includes a light-emitting element, a light-receiving element, an amplifier circuit that inputs the signal from the light-receiving element, a comparator that identifies the signal from the amplifier circuit with a threshold value, and a signal from the comparator. A PFM optical transmission system characterized by having an input low-pass filter on the receiving side.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2084105A JP3052328B2 (en) | 1990-03-30 | 1990-03-30 | PFM optical transmission system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2084105A JP3052328B2 (en) | 1990-03-30 | 1990-03-30 | PFM optical transmission system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03283928A true JPH03283928A (en) | 1991-12-13 |
| JP3052328B2 JP3052328B2 (en) | 2000-06-12 |
Family
ID=13821243
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2084105A Expired - Lifetime JP3052328B2 (en) | 1990-03-30 | 1990-03-30 | PFM optical transmission system |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3052328B2 (en) |
-
1990
- 1990-03-30 JP JP2084105A patent/JP3052328B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JP3052328B2 (en) | 2000-06-12 |
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