JPS63253926A - Branching device for submarine optical transmission line - Google Patents

Abstract

PURPOSE:To efficiently secure a backup line for a partial line fault, by providing a changeover switch which is controlled by the remote control, and can replace a transmission signal between each optical fiber for transmitting a signal in the same direction in the same submarine optical cable. CONSTITUTION:In the inside of a branching device 4, plural pairs of optical fibers contained in one cable are allowed to branch and connected in each direction, respectively. Among the optical fibers contained in one cable, with regard to each fiber for transmitting a signal in the direction for going to this branching device 4, or each fiber for transmitting a signal in the direction for going to the outside from this branching device 4, the transmission signal can be replaced by the remote control of changeover switches S1-S3. In such a way, even for a line fault of a submarine transmission line of a long distance, a backup line can be set efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applied to a transmission line for optical communication using a submarine optical cable. The present invention relates to a branching device for submarine optical cables installed under the sea. In particular, the present invention relates to a device in which a changeover switch is provided in the optical fiber inside the branching device, and the switch can be remotely controlled to change the signal transmission route of the transmission line when a failure occurs in the cable.

[Conventional technology]

In recent years, optical communication technology using fiber as a transmission medium has been put into practical use, and communication transmission lines using optical fibers are being constructed around the world. Among them, the Trans-Pacific Cable [Yoshinao Iwamoto: Application to full-scale optical submarine communications: Japanese science and technology'8
5 Reference Co. and Transatlantic Cable [Range et al., U.S.I.
EEE published magazine 5AC-2Nch 61984 (P
, Range: The SL Underse
aLightwave System: IEEE
Vol., SAC-2N16)], taking advantage of the characteristic that optical fiber cables are composed of multiple optical fibers, we can connect Japan to Guam and Hawaii, or the United States to the United Kingdom to France, by using branching equipment installed underwater. There are plans to construct a branch transmission line connecting the two. However, the details of this branching device are considered to be still in the study stage, and the concept of the buffer amplifier against line failures such as optical fiber breaks is not disclosed.

[Problem that the invention seeks to solve]

Undersea optical transmission systems carry out large-capacity communications over 10,000 telephone channels, and once a failure occurs, it has a significant impact on social and economic activities, and the lines must be restored as soon as possible. On the other hand, repairing problems in submarine cables requires a large amount of time and money, including dispatching repair equipment, searching lines, salvaging, and re-laying the cable after repair. Additionally, repair work is affected by ocean weather, so it is not uncommon for it to take several weeks to complete restoration. In such a case, it is necessary for line operation to set up the bank amplifier line until the repair is completed.

An object of the present invention is to provide a branching device equipped with an optical changeover switch that can efficiently secure a bank amplifier line in case of some line failures.

[Means for solving problems]

The present invention is characterized in that a branching device is provided with an optical switch capable of exchanging transmission signals between a plurality of uplinks or downlinks within the same cable.

That is, the present invention is characterized by being equipped with a changeover switch that is controlled by remote control and can switch transmission signals between optical fibers that transmit signals in the same direction within the same submarine optical cable.

[Effect]

Inside the branching device, a plurality of optical fiber pairs accommodated in one cable are branched and connected in each direction.

Of the optical fibers housed in one cable, those that transmit signals in the direction toward this branching device, or those that transmit signals in the direction outward from this branching device, can be controlled by remote control of a changeover switch. This allows the transmitted signals to be interchanged.

When a failure occurs in a part of the optical fiber housed in one cable and signal transmission becomes impossible, the signal transmitted through the optical fiber where the failure occurred is backed up by another land system or other transmission route. When a ground-to-ground transmission cannot be performed, a changeover switch can be operated to restore the ground-to-ground transmission line, which can be banked up using another transmission line, at the expense of the ground-to-ground transmission line.

〔Example〕

FIG. 1 is a configuration diagram of an embodiment of the present invention. Code 1.2.
3 is a relay device, and 4 is a branch device installed underwater. A line made up of a single optical fiber tree is denoted by the symbol C, and its subscript indicates the direction of signal transmission. For example, line C
I□ is a line that transmits a signal from relay device 1 to relay device 2, and line C2I is a line that transmits a signal from relay device 2 to relay device 1.

Generally, line Cij represents a line that transmits a signal from relay device i to relay device j. Capital letters St, St, and S3 are changeover switches that can mutually exchange uplink signals, and lowercase letters 81, s2, and s3 are changeover switches that can mutually exchange downlink signals. These changeover switches are located within the branching device and can be remotely controlled from land via cables. This remote control means will be explained in detail later.

For example, if the uplink C, □ becomes a failure between the device 1 and the branching device 4 at position 5 indicated by the X mark in FIG.
When the changeover switch S1 is activated by a command from the terminal station, the transmission signals of the lines C1□ and C10 are exchanged as shown by the solid line in Fig. 2, and the line CI□ is essentially secured, and instead, the line CI+ is used for the purpose. Transmission from device 1 to device 3 becomes impossible, and the line becomes essentially a faulty line. That is, line C
This means that line CI3 has taken over the failure of I2.

Submarine optical transmission systems often involve long-distance lines, such as across oceans. In addition, cable damage due to fishing and other causes may occur at a depth of 1,000 yen.
Most occur in shallow waters below 1000 m.

Therefore, such line switching is very advantageous in the following situations. For example, assume that device 1 is connected to the Tokyo terminal, device 3 is connected to the Osaka terminal, and device 2 is connected to the Okinawa terminal. Since multiple land transmission lines are provided between two of these three terminal stations, Tokyo and Osaka, the signal from device 1 to device 3 can be replaced by another land route.

Further, if the branching device 4 is installed in a relatively deep position in the water where fishing troubles and the like are less likely to occur, there is a high probability that a cable trouble will occur between the relay device 1 or 3 and the branching device 4.

In this way, if line Cl2 (for example, Tokyo-Okinawa) becomes a failure, as mentioned earlier, the changeover switch S switches the line signal and virtually secures lines b% c and z. Instead, line C83 (for example, Tokyo-Osaka) can be made the failed line. In this case, line C1□ (Tokyo-Osaka) can be back-amplified by a land line.

This makes it possible to temporarily secure all lines until the fault is repaired. In this way, by providing a line signal replacement function to a branching device installed underwater, it becomes easy to set up a backup line in case of a line failure.

As shown in the example, it is often difficult to prepare backup lines such as land and radio for long distance lines such as Tokyo and Okinawa, but instead, it is easy to set up backup lines between Tokyo and Osaka. .

Additionally, it is even more difficult to set up a backup line for a line that spans two countries, such as between Tokyo and Hawaii, and it is easier to set up a backup line within the same country, such as between Tokyo and Osaka. be. Considering that domestic communication networks are generally well developed in industrialized countries with high demand for communication, as shown in this example, the signal of the faulty line is replaced with a line where it is easy to obtain a backup line using another transmission line. By doing so, it becomes possible to achieve extremely practical and efficient operation of the line.

In this example, line C1! Although the above description has been made regarding the replacement between line C13 and line C13, the same applies to other lines. In addition, the switches SL % S 2 % S 3 , S H shown in FIG.
It is not necessarily necessary to prepare all of Sg and S3, and for parts where it is difficult to set up a backup line and there is no point in replacing them, the switch is not necessary.

Next, switch Sl, St, S:l, 31 SS
To explain the configuration for remotely controlling t and s3, it is preferable that each of these switches utilizes a dielectric optical switch element as a switch element. In a dielectric optical switch element, an optical signal propagates along one path in a dielectric waveguide when no bias voltage is applied, but when a bias voltage is applied, the propagation direction changes in the branched dielectric waveguide. It is subject to change. That is, in the device of the present invention,
In a steady state with no faults occurring, this dielectric optical switch element is used without applying a bias voltage.
When switching is performed by remote control, a bias voltage is applied. It is sufficient that the switched state, ie the bias voltage applied state, be maintained until the fault is repaired as described above. Therefore, in a steady state where no failure occurs, no extra power is consumed.

FIG. 3 is a block configuration diagram for supplying a bias voltage, which is a control signal, to the optical switch. It is connected by a conducting wire from a submarine optical transmission line repeater installed within the same housing of the branching device of the present invention or in the vicinity of the branching device. A supervisory switching signal is separated from a pair of optical repeaters 11 and 12 connected to a pair of optical fibers, and a supervisory switching circuit 13
supplied to

This monitoring switching circuit 13 is supplied with power from a power supply circuit inside the repeater, and a switching signal is sent to the conducting wire 15. This switching signal is a bias voltage for driving the above-mentioned optical switch element.

Regarding the configuration of this optical repeater, please refer to Volume 34 of the Research and Practical Application Report, a magazine published by the Research and Development Division of Nippon Telegraph and Telephone Corporation.
No. 8 (August 1985), p. 1163, Ito et al.
There is a detailed description in S-400M submarine optical repeater J. Regarding separation of monitoring switching signals by remote control,
From page 1173 of the above magazine, there is a detailed description of "Forestland rFS-400M Monitoring and Control System". In particular, the latter paper discloses a technique for transmitting multiple control signals from a terminal station using remote control, and switching the transmitting laser diode placed in the repeater to a spare one in accordance with the control signals. By utilizing some of these monitoring switching signals for switching the optical switch element of the present invention, the circuit shown in FIG. 3 above can be concretely realized.

〔Effect of the invention〕

As explained above, the present invention makes it possible to efficiently set up a backup line even in the event of a line failure on a long-distance submarine transmission line. Operational losses can be minimized.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of the present invention. Figure 2 is times+! An explanatory diagram of line signal replacement at the time of failure of fAc, □. FIG. 3 is a block diagram showing a circuit for generating a switching control signal for a changeover switch. 1.2.3... Relay device, 4... Branching device installed under the sea, 5... Line fault location, S+, St, S3
...Switch for uplink switching, 31% S2
, S3...Switch for downlink switching. Patent applicant: Nippon Telegraph and Telephone Corporation 7, agent: Naotaka Ide, patent attorney:'. Figure 1 Figure 3

Claims (1)

[Claims] (1) In a branching device that is installed underwater and connects three or more submarine optical cables that accommodate multiple pairs of optical fibers, the optical fibers that are controlled by remote control and that transmit signals in the same direction within the same submarine optical fiber are interconnected. A submarine optical transmission line branching device characterized by being equipped with a changeover switch that can switch transmission signals between the two.