JPS63284955A - Optical transmission system - Google Patents

Abstract

PURPOSE:To make speed conversion and also the rise of a transmission clock frequency unnecessary, by generating and transmitting two series of optical signal system strings for an information system string to be transmitted. CONSTITUTION:When the information system string 2 is inputted from a terminal 13 and a transmission clock 5 is inputted from a terminal 14 to a transmitter 12, outputs synchronized with the transmission clock 5 are sent from a gate circuit 16 at a part where a signal is 1 and from a gate circuit 17 at the part where the signal is 0 to light emitting elements 18 and 19. The light emitting elements 18 and 19 send light having wavelength lambda1 and lambda2 to an optical fiber 20 sensing to the outputs of the gate circuits 16 and 17, respectively. Meanwhile, the light receiving elements 22 and 23 of a receiver 21 sense to the light having wavelength lambda1 and lambda2, and send their emitting outputs to reproduction circuits 24 and 25. And at the reproduction circuits 24 and 25, respective reception code system string is reproduced, and those are added on the outputs at a timing generation circuit 26, then outputted from a terminal 30.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical transmission system using an optical transmission line, and particularly to a transmission line encoding system.

[Conventional technology] In optical transmission systems that transmit digital information using light,
In order to obtain good transmission quality, bit sequence independence (B
It Sequence Independence
(hereinafter referred to as BSI) conditions must be met.

Figure 4 shows, for example, Research and Practical Application Report Volume 28 No. 9 (19
"32Mb/s and I 00Mb/S Digital Optical Cable Transmission System" published on pages 21 to 46 of Nippon Telegraph and Telephone Public Corporation in 1979, and Research and Practical Application Report Volume 32, No. 3 (Nippon Telegraph and Telephone Public Corporation, published in 1983 (Published by Public Corporation), page 23~
This is a time chart showing such a conventional optical transmission method as shown in "Design and Characteristics of rF-400M Terminal Repeater Equipment" published on page 34. In the figure, 1 is the bit number and 2 is the transmission time. 3 is a coded mark inversion (Coded M
arkI nvrsion (hereinafter referred to as CMI) encoding system, 4 is the information sequence 2 m
Binary with ■Compliment Insertion (m Binary with I Complete
ENT I n5-ers ion) is a type of method.
= 10 (hereinafter referred to as l0BIC)
: This is a code sequence encoded using the encoding method).

Next, the operation will be explained. In the code sequence based on the CMI encoding method, the transmission path clock frequency is twice the frequency of the information sequence 2 to be transmitted, a “0!” pattern is assigned to the “0” signal of the information sequence 2, and the “l” It assigns a “00” pattern or “11” pattern to the signal, and each time a “1” signal occurs in information series 2,
Change the pattern from “00” to “11” or “11”
By alternately inverting the pattern from to “00”, “0”
``If the number of consecutive signals is 3 or less and the mark rate is 1/2,
Encoding is performed that satisfies the S1 condition.

Furthermore, code sequence 4 based on the l0BIC encoding method is (i
o + 1)/10 speed conversion to secure 1 redundant bit for every 10 bits, put the 1st to 10th bits of the information sequence 2 to be transmitted on the 1st to 10th bits, and The information sequence 2 is added to the redundant bit of the bit.
In the illustrated example, the shaded 11th bit is the 8th bit "0".
An "l" signal obtained by inverting the signal is carried as a complementary code. As a result, the worst number of consecutive "0" signals can be suppressed to within 10+1, and encoding that satisfies the BS1 condition is performed.

Problems that the invention attempts to solve] Since the conventional optical transmission system is configured as described above,
The CMI encoding method not only doubles the transmission path clock frequency, but also requires a transmission band that is twice the information transmission speed.
OI' (In the IC encoding method, the transmission line clock frequency is (10+1)/IO times the transmission line clock frequency for the information series to be transmitted, so speed conversion with the clock source is required, making the device complex. There was a problem.

This invention was made in order to solve the problems mentioned in 1. This invention is a BS system that does not increase the transmission line clock frequency, does not require speed conversion, and allows easy reception timing recovery.
The objective is to obtain an optical transmission system that satisfies one condition.

[Means for Solving the Problems] The optical transmission system according to the present invention includes: a first optical signal sequence that emits light when the signal of the information sequence to be transmitted is “l” and extinguishes when it is “0”; A second optical signal sequence that is extinguished when the on-plane information sequence signal is "B" and emitted when it is "°0" is transmitted to the optical transmission line, and the first and second optical signal sequences received from the optical transmission line are transmitted. It reproduces the information series sent from.

[Operation] The optical transmission system of the present invention generates two optical signal sequences for the information sequence to be transmitted, so that when the signal of the information sequence is "I", one optical signal sequence causes light to be emitted. When the signal of the information series is "O", it is possible to extinguish light with one optical signal series and cause light emission with the other optical signal series, without the need for speed conversion. To realize an optical transmission system that satisfies BS1 conditions without increasing the transmission line clock frequency.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
In the figure, l is a bit number and 2 is an information sequence to be transmitted, which are the same as those in the conventional system, which are given the same reference numerals in FIG. 5 is the transmission clock, 6 is the information series 2
7 is the second optical signal sequence generated for the information sequence 2;
The optical signal series 6 emits light when the signal of the information series 2 is "1" and extinguishes when the signal of the information series 2 is "0", and the second optical signal series 7 emits light when the signal of the information series 2 is "0". The light quenches when the temperature is 0°l''. Further, 8 is a received code sequence generated from the first optical signal sequence 6, 9 is a received code sequence generated from the second optical signal sequence 7, and 10 is the received code sequence 8.
．． 9 is the reproduction timing, and 11 is the reproduction code sequence that is also reproduced from the received code sequence 8.9.

FIG. 2 is a block diagram showing an example of a transmitting device. In the figure, 12 is a transmitting device, 13 is a terminal to which the information series 2 to be transmitted is input, and 14 is a terminal to which the transmitting clock 5 is input. Terminal 15 is an inversion circuit that inverts the polarity of the information series 2 input manually from the terminal 13, 16 is a gate circuit that takes the AND of the information series 2 from the terminal 11 and the transmission clock 5 from the terminal 14, and 17 is an inversion circuit. A gate circuit 18 which calculates the logical product of the output of the circuit I5 and the transmission clock 5 from the terminal 14 emits light of wavelength λ1, and operates with the output of the gate circuit 16 to generate the first optical signal series 6 in trj. A light-emitting element that generates! 9 emits light of wavelength λ, and gate circuit 17
A light emitting element 20 is coupled to each of these light emitting elements 18, 19 to generate the first optical signal sequence 6 and the second optical signal sequence 7. An optical fiber serves as an optical transmission line for transmission.

Furthermore, FIG. 3 is a block diagram showing an example of a receiving device, and in the figure, 21 is a receiving device, 22 is coupled to the optical fiber 20 and is sensitive only to the wavelength λ1, and the first
A light receiving element 23 receiving the optical signal sequence 6 is also coupled to the optical fiber 20 and is sensitive only to light of wavelength λ,
A light receiving element 24 receives the second optical signal sequence 7; 24 is a regenerative receiving unit that generates a reception code sequence 8 corresponding to the first optical signal sequence 6 from the output of the light receiving element 22; 25 is the light receiving element 25; a reproducing receiver unit 2 that reproduces the received code sequence 9 corresponding to the second optical signal sequence 7 from the output of the element 23;
Reference numeral 6 indicates a timing and timing reproducing section for regenerating the reproducing timing lO based on the received code sequences 8.9 outputted by the reproducing receiving sections 24 and 25, and 27 indicates the polarity of the receiving code sequence 8 outputted from the reproducing receiving section 24. 28 is a flip-flop that reproduces the reproduced code series 11 based on the outputs of the reproduction receiving section 24, the inverting circuit 27, and the timing reproducing section 26; 29 is a terminal for outputting the reproduced code series 11; 30 is the This is a terminal that outputs playback timing 10.

Next, the operation will be explained. In the transmitting device 12, terminal 1
When the information series 2 to be transmitted is manually input from terminal 3 and the transmission clock 5 is input from terminal 14, gate circuits I6 and 17
and operate complementary to each other due to the action of the inverting circuit 15, and when the signal of the information series 2 is "B", the signal from the gate circuit 16 is "0".
”, an output synchronized with the transmission clock 5 is sent from the gate circuit 17 to the light emitting element 18 or I9. The light emitting element 18 emits light of wavelength λ1 in response to the output of the gate circuit 16, and the first generates an optical signal sequence 6 and sends it to the optical fiber 20. Similarly, the light emitting element 19 emits light of wavelength λ in response to the output of the gate circuit 17,
A second optical signal sequence 7 is generated and sent to the optical fiber 20. Therefore, in the first optical signal series 6, the signal of the information series 2 emits light when it is "B" and extinguishes when it is "0", and in the second optical signal series 7, the signal of the information series 2 emits light when it is "B". and 0
Lights up when the temperature is ゜.

The first and second optical signal sequences 6.7 sent from the transmitting device 12 to the optical fiber 20 in this way are transmitted to the receiving device 21.
The light is then transmitted to the light receiving elements 22 and 23. The light-receiving element 22 receives the first optical signal sequence 6 by being sensitive only to the light having the wavelength λ1, and the light-receiving element 23 receives the second optical signal sequence 7 by being sensitive only to the light having the wavelength λ. This light receiving element 2
The output of 2 is sent to the reproducing receiver 24, and the output of the light receiving element 23 is sent to the reproducing receiver 25, where they are reproduced as received code sequences 8 and 9, respectively, and input to the timing reproducing circuit 26. The timing regeneration circuit 26 adds these received code sequences 8 and 9, and after further performing jitter suppression, delay adjustment, etc., outputs the signal to the terminal 3 as the regeneration timing IO
Output from 0.

On the other hand, the received code sequence 8 outputted from the reproducing receiving section 24 is sent to the flip-flop 28 directly and via the inverting circuit 27.
The flip-flop 28 receives the regeneration timing 10 outputted from both of these inputs and the timing reproducing section 26.
The reproduced code series II is reproduced based on this and outputted from the terminal 29.

Note that in the above embodiment, the signal “I” of the information series to be transmitted is
, the optical signal of the first optical signal series is emitted, and the second optical signal is emitted.
The optical signal of the optical signal series is quenched, and the first
In this example, the optical signal of the second optical signal sequence is extinguished and the optical signal of the second optical signal sequence is emitted.
It is also possible to drive the optical signals of both optical signal series to emit light or to extinguish it.

Furthermore, in the above embodiment, the case where there is one optical transmission line has been described, but two systems may be prepared and the first optical signal series and the second optical signal series may be transmitted through different optical transmission lines. In that case, it is also possible to use light of the same wavelength for the first optical signal series and the second optical signal series.

[Effects of the Invention] As described above, according to the present invention, two optical signal sequences are generated for the information sequence to be transmitted, and when the signal of the on-plane information sequence is “O”, one optical signal sequence is generated. The structure is configured so that when the signal is "I", one optical signal sequence causes the light to emit light and the other optical signal sequence causes the light to emit light, and the other optical signal sequence causes the light to emit light, so there is no need for speed conversion and the transmission line clock frequency can be reduced. B, which does not increase the reception timing and makes it easy to recover the reception timing.
This has the effect of realizing an optical transmission system that satisfies the S1 condition.

[Brief explanation of drawings]

FIG. 1 is a time chart showing an optical transmission system according to an embodiment of the present invention, FIG. 2 is a block diagram showing its transmitting device, FIG. 3 is a block diagram showing its receiving device, and FIG. 4 is a conventional optical transmission system. It is a time chart showing a transmission method. 2 is an information sequence to be transmitted, 6 is a first optical signal sequence, 7 is a second optical signal sequence, 8.9 is a received code sequence, IO is a reproduction timing, 11 is a reproduction code sequence, 12 is a transmitter, 2
0 is an optical transmission line (optical fiber <), and 21 is a receiving device. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Figure 2 20: Katsuden L26 (Kumiiba → Figure 3

Claims (6)

[Claims] (1) In an optical transmission system in which a transmitting device and a receiving device are connected by an optical transmission path and an information sequence based on an optical signal is transmitted onto the optical transmission path, the transmitting device transmits a signal of the information sequence “1”. A first optical signal series that emits light when the signal is "0" and extinguishes when it is "0", and a second optical signal series that emits light when the signal of the information series is "1" and emits light when it is "0". An optical transmission system, wherein the information sequence is transmitted to a transmission path, and the receiving device reproduces the information sequence from the first and second optical signal sequences received from the optical transmission path. (2) The receiving device reproduces a received code sequence for each system from the first and second optical signal sequences, adds and synthesizes the received code sequences of the respective systems, and determines the reproduction timing. 2. The optical transmission system according to claim 1, wherein the optical transmission system generates a reproduced code sequence. (3) The first and second optical signal series include a special signal that causes both systems to emit light or both systems to extinguish during a part or all of the transmission period. Optical transmission method described in scope 1. (4) Use lights of different wavelengths as the light of the first optical signal series and the light of the second optical signal series, and transmit the first and second optical signal series on the same optical transmission path. An optical transmission system according to any one of claims 1 to 3, characterized in that the optical transmission system transmits an optical signal. (5) The first optical signal series and the second optical signal series are transmitted on separate optical transmission paths. Optical transmission method described in section. (6) The optical transmission system according to claim 5, characterized in that the light of the first optical signal series and the light of the second optical signal series have the same wavelength.