JPS6322695B2 - - Google Patents
Info
- Publication number
- JPS6322695B2 JPS6322695B2 JP56147371A JP14737181A JPS6322695B2 JP S6322695 B2 JPS6322695 B2 JP S6322695B2 JP 56147371 A JP56147371 A JP 56147371A JP 14737181 A JP14737181 A JP 14737181A JP S6322695 B2 JPS6322695 B2 JP S6322695B2
- Authority
- JP
- Japan
- Prior art keywords
- signal
- level
- input
- output
- optical
- 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
- 230000003287 optical effect Effects 0.000 claims description 36
- 230000008054 signal transmission Effects 0.000 claims description 12
- 238000000034 method Methods 0.000 claims description 5
- 230000005540 biological transmission Effects 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 12
- 230000006835 compression Effects 0.000 description 4
- 238000007906 compression Methods 0.000 description 4
- 239000013307 optical fiber Substances 0.000 description 4
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/62—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission for providing a predistortion of the signal in the transmitter and corresponding correction in the receiver, e.g. for improving the signal/noise ratio
- H04B1/64—Volume compression or expansion arrangements
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Reduction Or Emphasis Of Bandwidth Of Signals (AREA)
- Optical Communication System (AREA)
Description
【発明の詳細な説明】
本発明は、信号伝送に付随する基本雑音ならび
に過負荷を改善する方法に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for improving the fundamental noise and overload associated with signal transmission.
一般に光信号伝送では、入力の電気信号のレベ
ルの大小を光レベルの大小に対応させる光強度変
調が用いられる。 Generally, optical signal transmission uses optical intensity modulation in which the level of an input electrical signal corresponds to the level of light.
第１図〜第３図により、光強度変調を用いた光
信号伝送方法の従来例を説明する。 A conventional example of an optical signal transmission method using optical intensity modulation will be explained with reference to FIGS. 1 to 3.
第１図は、従来の光強度変調を用いた光アナロ
グ信号伝送の構成を示す図である。図において、
１は入力端子、２は変調器、３は駆動回路、４は
発光素子、５は光フアイバ、６は受光素子、７は
増幅回路、８は復調器、９は出力端子である。 FIG. 1 is a diagram showing the configuration of optical analog signal transmission using conventional optical intensity modulation. In the figure,
1 is an input terminal, 2 is a modulator, 3 is a drive circuit, 4 is a light emitting element, 5 is an optical fiber, 6 is a light receiving element, 7 is an amplifier circuit, 8 is a demodulator, and 9 is an output terminal.
第２図は、送信部での入出力特性を示す図であ
る。図において、縦軸ａは光信号のレベル、横軸
ｂは入力信号のレベル、ｃはオーバーロードしな
い範囲、ｄは送信部の入出力特性を示す。 FIG. 2 is a diagram showing input/output characteristics in the transmitter. In the figure, the vertical axis a shows the level of the optical signal, the horizontal axis b shows the level of the input signal, c shows the range without overload, and d shows the input/output characteristics of the transmitter.
第３図は、受光部での入出力特性を示す図であ
る。図において、縦軸ｅは出力信号のレベル、横
軸ｆは入力信号のレベル、ｇは出力部の入出力特
性を示す。 FIG. 3 is a diagram showing input/output characteristics at the light receiving section. In the figure, the vertical axis e represents the level of the output signal, the horizontal axis f represents the level of the input signal, and g represents the input/output characteristics of the output section.
まず、入力端子１に入力情報が入力される。こ
の入力情報は、変調器２によつて、電気信号の振
幅に対応させる。すなわち、入力情報を変調器２
によつて振幅変調する。この変調によつて得られ
たアナログ信号は、駆動回路３に入力される。駆
動回路３は発光素子４を駆動し、第２図に示すよ
うに駆動信号のレベルの大小を直接、光信号のレ
ベルの大小に対応させる。すなわち、光強度変調
を行う。これによつて得られた光信号は光フアイ
バ５を介して受光素子６で受信される。受光素子
６は第３図に示すように受信した光信号のレベル
の大小を出力される電気信号のレベルの大小に対
応させる。この電気信号は増幅回路７で増幅さ
れ、復調器８に入力される。復調器８では信号を
復調して出力端子９に出力する。 First, input information is input to the input terminal 1. This input information is made to correspond to the amplitude of the electrical signal by the modulator 2. That is, input information is transmitted to modulator 2
The amplitude is modulated by The analog signal obtained by this modulation is input to the drive circuit 3. The drive circuit 3 drives the light emitting element 4, and as shown in FIG. 2, the level of the drive signal directly corresponds to the level of the optical signal. That is, light intensity modulation is performed. The optical signal thus obtained is received by the light receiving element 6 via the optical fiber 5. As shown in FIG. 3, the light receiving element 6 makes the level of the received optical signal correspond to the level of the output electrical signal. This electrical signal is amplified by an amplifier circuit 7 and input to a demodulator 8. The demodulator 8 demodulates the signal and outputs it to the output terminal 9.
しかしながら、かかる従来の構成では、以下の
欠点が生じる。 However, such a conventional configuration has the following drawbacks.
光信号伝送では送信部から受信部に光信号が送
られてくると受信部の受光素子６や増幅回路７で
は、雑音が発生し、この雑音が出力信号に重畳さ
れることになる。この受光素子６や増幅回路７で
発生する雑音は、受信される光信号のレベルの大
きい領域では受光素子６で発生するシヨツト雑音
が主体となり、小さい領域では増幅回路７で発生
する熱雑音が主体となる。また、これらの雑音
は、受信される光信号のレベルの関数で表わされ
る。すなわち、受信光信号のレベルが大きくなる
と雑音の影響は大きくなる。 In optical signal transmission, when an optical signal is sent from a transmitter to a receiver, noise is generated in the light receiving element 6 and amplifier circuit 7 of the receiver, and this noise is superimposed on the output signal. The noise generated in the light receiving element 6 and the amplifier circuit 7 is mainly shot noise generated in the light receiving element 6 in areas where the level of the received optical signal is high, and thermal noise generated in the amplifier circuit 7 in areas where the level of the received optical signal is low. becomes. Additionally, these noises are expressed as a function of the level of the received optical signal. That is, as the level of the received optical signal increases, the influence of noise increases.
一方、光信号伝送方式では光強度変調を用い、
入力信号のレベルの大小を光信号のレベルの大小
として送る。ここでは、入力信号を正負両極性に
等しく変化させる。 On the other hand, optical signal transmission systems use optical intensity modulation,
The level of the input signal is sent as the level of the optical signal. Here, the input signal is changed equally to both positive and negative polarities.
従つて、雑音の影響を減らし、良好なSN比で
信号を受信するために信号レベルを下げた場合に
は、第２図に示す駆動信号のレベルが図中Ｃで示
す発光素子の駆動トランジスタがオーバーロード
しない範囲を超えてしまう欠点があつた。 Therefore, when the signal level is lowered to reduce the influence of noise and receive signals with a good signal-to-noise ratio, the level of the drive signal shown in FIG. It had the drawback of exceeding the non-overload range.
本発明は、かかる欠点を除去し、雑音の劣化を
少なくし、且つ過負荷を改善する光信号伝送方法
を実現することを目的としている。 The present invention aims to eliminate such drawbacks, reduce noise degradation, and realize an optical signal transmission method that improves overload.
第４図は、本発明の光信号伝送方法の一構成例
を示す図である。ここでは第１図に示した構成に
圧縮器１０及び伸長器１１を付加したものであ
る。 FIG. 4 is a diagram showing a configuration example of the optical signal transmission method of the present invention. Here, a compressor 10 and an expander 11 are added to the configuration shown in FIG.
第５図は送信部の圧縮特性を示す図である。図
において、縦軸ａは光信号のレベル、横軸ｂは入
力信号のレベル、破線ｄは従来の送信部の入出力
特性、ｈは本発明によるオーバーロードしない範
囲、ｉは送信部の圧縮（入出力）特性を示す。ま
た図中の入力信号のレベルｂとは、第４図の変調
器２の出力レベルを示し、光アナログ信号のレベ
ルａとは第４図の発光素子４の出力レベルを示
す。 FIG. 5 is a diagram showing the compression characteristics of the transmitter. In the figure, the vertical axis a is the level of the optical signal, the horizontal axis b is the level of the input signal, the broken line d is the input/output characteristic of the conventional transmitter, h is the range without overload according to the present invention, and i is the compression of the transmitter ( Input/output) characteristics. Further, the level b of the input signal in the figure indicates the output level of the modulator 2 in FIG. 4, and the level a of the optical analog signal indicates the output level of the light emitting element 4 in FIG. 4.
第６図は受信部の伸長特性を示す図である。図
において、縦軸ｅは出力信号のレベル、横軸ｆは
受信光信号のレベル、ｇは従来の受信部の入出力
特性、ｊは受信部の伸長（入出力）特性を示す。
また図中の受信光信号のレベルｆとは、第４図の
受光器６の出力レベルを示し、出力信号のレベル
ｅとは第４図の復調器８への入力レベルを示す。 FIG. 6 is a diagram showing the expansion characteristics of the receiving section. In the figure, the vertical axis e represents the level of the output signal, the horizontal axis f represents the level of the received optical signal, g represents the input/output characteristic of the conventional receiving section, and j represents the expansion (input/output) characteristic of the receiving section.
Further, the level f of the received optical signal in the figure indicates the output level of the optical receiver 6 in FIG. 4, and the level e of the output signal indicates the input level to the demodulator 8 in FIG. 4.
以下、第４図〜第６図により、本発明の実施例
の動作を説明する。 The operation of the embodiment of the present invention will be described below with reference to FIGS. 4 to 6.
まず、入力端子１に入力情報が入力される。こ
の入力情報は変調器２によつて変調され、圧縮器
１０に入力される。圧縮器１０は、第５図ｉに示
すような圧縮特性を持つており、変調器２からの
信号の圧縮を行い、駆動回路３に送出する。駆動
回路３は、発光素子４を駆動し、圧縮器１０で圧
縮された信号のレベルの大小を直接、光信号レベ
ルの大小に対応させる。このようにして得られた
光信号は、光フアイバ５を介して、受光素子６に
入力される。受光素子６は受信した光信号のレベ
ルの大小を出力信号のレベルの大小に対応させ
る。この出力信号は、増幅回路７で増幅されてか
ら伸長器１１に入力される。伸長器１１は第６図
ｊに示すような伸長特性を持つており、増幅回路
７の出力信号の伸長を行い、復調回路８に送出す
る。復調回路８は伸長器１１で伸長されたアナロ
グ信号を復調し、出力端子９から出力する。すな
わち、本発明では送信部の圧縮器１０では第５図
に示すように、変調器２からの信号レベルの小さ
い領域を圧縮して、光出力信号のレベルを下げ、
受信部の伸長器１１では第６図に示すように受光
素子６からの出力信号のレベルの小さい領域を伸
長することにより、変調器２で変調して得られた
信号が伸長器１１の出力で得られることになる。 First, input information is input to the input terminal 1. This input information is modulated by modulator 2 and input to compressor 10. The compressor 10 has compression characteristics as shown in FIG. The drive circuit 3 drives the light emitting element 4 and makes the level of the signal compressed by the compressor 10 directly correspond to the level of the optical signal. The optical signal obtained in this way is input to the light receiving element 6 via the optical fiber 5. The light receiving element 6 makes the level of the received optical signal correspond to the level of the output signal. This output signal is amplified by the amplifier circuit 7 and then input to the expander 11. The expander 11 has an expansion characteristic as shown in FIG. The demodulation circuit 8 demodulates the analog signal expanded by the expander 11 and outputs it from the output terminal 9. That is, in the present invention, as shown in FIG. 5, the compressor 10 of the transmitter compresses the area where the signal level from the modulator 2 is low to lower the level of the optical output signal.
As shown in FIG. 6, the expander 11 in the receiving section expands the region where the level of the output signal from the light receiving element 6 is low, so that the signal modulated by the modulator 2 becomes the output of the expander 11. You will get it.
以上の説明から明らかな如く、本発明によれば
送信部で、アナログ信号のレベルの小さい領域を
圧縮し、光出力のレベルを抑えるので、受信側で
の雑音発生を抑圧するとができる。また、第５図
に示すように、負側の発光素子の駆動トランジス
タがオーバーロードしない範囲を拡大し、入力ダ
イナミツクレンジを広くすることができる。 As is clear from the above description, according to the present invention, the transmitting section compresses the region where the level of the analog signal is low and suppresses the level of the optical output, so that it is possible to suppress the generation of noise on the receiving side. Furthermore, as shown in FIG. 5, the range in which the driving transistor of the negative-side light emitting element is not overloaded can be expanded, and the input dynamic range can be widened.
第１図は従来の光信号伝送の構成を示す図、第
２図は従来の送信部での入出力特性を示す図、第
３図は、従来の受信での入出力特性を示す図、第
４図は本発明の光信号伝送の１構成例を示す図、
第５図は送信部の圧縮特性を示す図、第６図は受
信部の伸長特性を示す図である。
図中、１は入力端子、２は変調器、３は駆動回
路、４は発光素子、５は光フアイバ、６は受光素
子、７は増幅回路、８は復調器、９は出力端子、
１０は圧縮器、１１は伸長器を示す。
Fig. 1 is a diagram showing the configuration of conventional optical signal transmission, Fig. 2 is a diagram showing the input/output characteristics in the conventional transmitter, and Fig. 3 is a diagram showing the input/output characteristics in conventional reception. FIG. 4 is a diagram showing an example of the configuration of optical signal transmission of the present invention,
FIG. 5 is a diagram showing the compression characteristics of the transmitting section, and FIG. 6 is a diagram showing the expansion characteristics of the receiving section. In the figure, 1 is an input terminal, 2 is a modulator, 3 is a drive circuit, 4 is a light emitting element, 5 is an optical fiber, 6 is a light receiving element, 7 is an amplifier circuit, 8 is a demodulator, 9 is an output terminal,
10 is a compressor, and 11 is an expander.
Claims (1)
へ送出する光信号伝送方式に於いて、 送信部では光変調される入力信号の信号レベル
が小さい領域を予め圧縮してから発光素子へ入力
し、 受信部では受光素子により光／電変換された受
信信号の信号レベルが小さい領域を伸張すること
を特徴とする光信号伝送方式。[Claims] 1. In an optical signal transmission system in which a transmission signal is modulated by optical intensity modulation and sent to the receiving side, the transmitting section compresses in advance an area where the signal level of the input signal to be optically modulated is low. An optical signal transmission method characterized in that a received signal is input to a light-emitting element from a light-emitting element, and is optically/electrically converted by a light-receiving element in a receiving section, and the signal level of the received signal is low.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56147371A JPS5848541A (en) | 1981-09-18 | 1981-09-18 | Optical signal transmission method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56147371A JPS5848541A (en) | 1981-09-18 | 1981-09-18 | Optical signal transmission method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5848541A JPS5848541A (en) | 1983-03-22 |
| JPS6322695B2 true JPS6322695B2 (en) | 1988-05-12 |
Family
ID=15428711
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP56147371A Granted JPS5848541A (en) | 1981-09-18 | 1981-09-18 | Optical signal transmission method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5848541A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63187933A (en) * | 1987-01-30 | 1988-08-03 | Matsushita Electric Ind Co Ltd | On vehicle audio device |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54118154A (en) * | 1978-03-07 | 1979-09-13 | Nec Corp | Signal amplitude compander featuring polygonal line characteristics |
-
1981
- 1981-09-18 JP JP56147371A patent/JPS5848541A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54118154A (en) * | 1978-03-07 | 1979-09-13 | Nec Corp | Signal amplitude compander featuring polygonal line characteristics |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5848541A (en) | 1983-03-22 |
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