JPS60194645A - Loop transmission system - Google Patents

Abstract

PURPOSE:To simplify the constitution of the loop transmission system and to reduce its cost by connecting two branching filters to right and left transmission lines of each node station respectively, transmitting a signal from the node station through a looped transmission line clockwise and counterclockwise, and returning the signal when a circuit becomes faulty. CONSTITUTION:A two-way wavelength multiplex transmission line is provided between each node station and its adjacent node station. This basic transmission line consists of a branching filter 61 and an optical fiber 62 and allows two-way transmission with the one optical fiber so that a signal with wavelength 1 is transmitted counterclockwise and a signal with 2 is transmitted clockwise. If the optical fiber is broken at, for example, a point 30, the signals are returned 31 by the stations at both terminals of the section wherein the trouble occurs to set a loop transmission line. Thus, circuit trouble is handled even with one transmission line and the station becomes unable to receive the signal only change connection of its exchange slightly to attain alteration into the return constitution easily in case of circuit trouble.

Description

DETAILED DESCRIPTION OF THE INVENTION [FV Fan and Objective 1 of the Invention The present invention relates to a loop transmission method, particularly a novel transmission method using optical wavelength multiplexing technology.

FIG. 1 shows the configuration of a typical optical loop transmission system known in the past, in which the transmission line 12 is connected to the current loop 12.
a and a backup loop 12b, and the former working loop 12a is always used.

There are node stations 1 at various places on the loop transmission line 12.
1a, 11b, llc... are provided to receive signals from data equipment 10 such as computers and data terminals.
It acts to put it into the loop 12 and take it out from the loop 12.

Here, the term "node" means a turning point, and the node stations 11 are connected by a single stroke.

For example, the signal from the computer 10a is transmitted to the terminal device 1.
If sending to 0c, Combi'',-Y 10a sends a signal to node station lla, which in turn transmits the signal to Toos station 11C,
Here, the signal is taken out of the loop and input to the terminal equipment 10c.

By the way, when a failure occurs in this transmission system, for example, a cable break as shown at 13 in FIG. 1, the node stations 11a on both sides of the point 13 where the problem occurs.

In the lid, each node station 1 has a folded structure of the loop 12 as shown in 14a and 14b.
1 to enable normal signal transmission.

This example shows a case where all the transmission paths in the loop are broken, but even if only the working loop is broken, the communication function is maintained by the above-mentioned loopback.

Note that in the case of a disconnection in only the working loop, the communication path may be switched to the backup loop without loopback.

The above has described the optical loop transmission method that has been in practical use for a long time, but this method requires duplication from the viewpoint of system reliability, which increases the cost and makes it difficult to control the circuit configuration. It had the disadvantage of being complicated.

An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a loop transmission system that is extremely easy to configure.

[Summary of the present invention] That is, the gist of the present invention is to connect adjacent node stations with a single transmission line to configure a loop-shaped bidirectional wavelength division multiplexing transmission line. duplexers are connected to the left and right transmission lines, respectively, and the input/output terminals of the duplexers are connected to a data processing circuit, and according to the commands of the data processing circuit,
This loop transmission method is characterized in that a signal output from a node station can be rotated clockwise or counterclockwise on a loop-shaped transmission line, so that in the event of a circuit failure, the signal is looped back and transmitted.

[Embodiments of the Invention] Next, embodiments of the present invention will be further described with reference to the accompanying drawings 2 to 6.

First, a bidirectional wavelength multiplex transmission path is provided between each node station and an adjacent node station.

As shown in Fig. 4, this basic transmission line consists of a demultiplexer 61 and an optical fiber 62, and the signal with wavelength λ1 goes leftward in the drawing, and the signal λ2 goes rightward, and is transmitted bidirectionally through a single optical fiber. is possible.

In FIG. 2, the basic bidirectional wavelength multiplexing transmission line shown in FIG. 4 is provided between all adjacent stations.

Therefore, each node station lla, b, c, d has
Two optical fibers are inserted into each, and two demultiplexers are also required.

In this system, the clockwise signal goes around a loop as shown by the dashed line in FIG.

Further, the counterclockwise signal can also go around the loop in the same way.

Since these left-handed and right-handed signals have different wavelengths, they can be transmitted independently without interfering with each other.

In FIG. 3, the folding configuration in the case where the optical fiber is broken at, for example, 30 points is shown by broken lines.

That is, a loop transmission path can be established by performing loopback 31 at the stations at both ends of the section where the failure has occurred.

FIG. 5 shows the details of the two-tooth duplex, in which the optical fibers 20a and 20b pass through the optical switch 40 and enter the demultiplexers 21a and 21b.

The optical switch 40 is normally connected as shown by a solid line, but when this station has a failure (for example, a power outage), it becomes connected as shown by a broken line, and this station is bypassed.

The demultiplexers 21a and 21b are optical transmitter 1151 and optical receiver 11
52, and the optical transceiver is further connected to an exchange 55.

That is, the output of the exchanger 55 is converted from electricity to light in the optical transmission 1fi 51 and sent out to the optical fiber, and is converted from light to an electrical signal in the optical reception @ 52 and enters the exchanger 55.

A data processing circuit 56 is connected to the end of the exchanger 55, and here exchanges and stores signals with a data device 57, creates a signal format for sending signals to a transmission path, detects data errors, and processes signals. It also has other complex functions such as abnormality processing.

It also issues an instruction to the exchange control circuit 54 to change the connection of the exchange, and receives a signal for detecting a circuit failure by monitoring the supervisory signal from the optical receiver 52 with the receiving circuit 53.

The exchanger 55 is used to change the transmission form of the loop transmission line in various ways, and normally it is configured as a clockwise transmission line as shown by the solid line in FIG. It can also be done around you.

On the other hand, if a circuit abnormality is detected, the signal is looped back in this station controller as shown in the actual output or broken line J in FIG. 6(2).

This exchanger 55 has three inputs and three outputs, and can be realized with a small number of extremely simple digital ICs.

In the above description, only embodiments of optical fiber transmission lines have been described, but the present invention is applicable not only to optical fibers but also to coaxial cables or couple pairs.
In this case, if we replace the wavelength with the frequency, the optical transmitter with the modulator, the optical receiver with the demodulator, and the optical switch with the relay, we get
The electrical loop transmission method is 1q.

In addition, in this embodiment, an example of three wavelengths has been explained, but it is also possible to use three wavelengths or more. In this case, the transmission capacity will increase, and the degree of freedom in network configuration will be significantly increased. However, the present invention is not limited to this embodiment.

[Effects of the Invention] As explained above, the transmission system of the present invention can cope with circuit failures even if there is only one transmission line, and the modification to the loopback configuration in the event of a circuit failure will result in the inability to receive signals. The advantage is that it is extremely easy to replace a stationary controller that has been damaged by simply changing the connection of the exchanger at your location.

Furthermore, since left-handed and right-handed transmission can be performed simultaneously and independently, the transmission capacity can be greatly increased, and its industrial value is extremely large.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an example of a conventional optical loop transmission system, Figs. 2, 3, and 4 are explanatory diagrams of the principle of the wavelength division multiplexing loop transmission system of the present invention. An explanatory diagram of one embodiment without showing the details of the node station section, FIG. 6 (1),
(2) is an explanatory diagram of an embodiment showing the operation of the exchanger. 10: Computer or data terminal 11: Node station 12. 62, 20: Optical fiber 13, 30: Optical fiber break point 14. 31: Signal return path 21, 61
: Duplexer 51: Optical transmitter 52: Optical receiver 53: Monitoring signal receiving circuit 54: Exchange control circuit 55:
Exchanger 56: Data processing circuit 57: Data equipment

Claims (1)

[Claims] (1) In a system that connects adjacent node stations with a single transmission line to form a loop-shaped bidirectional wavelength division multiplexing transmission line, in each node station, two demultiplexers are used to separate the left and right transmission lines. The input and output terminals of the duplexer are connected to a data processing circuit, and according to the instructions of the data processing circuit, the signal leaving the node station is routed along the loop-shaped transmission line. turn right,
Alternatively, a loop transmission method is characterized in that it can be rotated counterclockwise and the signal is looped back and transmitted in the event of a circuit failure.