JP2826451B2 - Optical submarine cable system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical submarine cable locating method for locating an optical submarine cable by using a magnetic tracing, and more particularly, to an optical submarine cable locating method which enables magnetic tracing in an arbitrary section. About. Further, the present invention relates to an optical submarine cable system suitable for performing the method.

[0002]

2. Description of the Related Art In general, in repair work of a submarine cable, it is necessary to search for the position of the laid submarine cable on the sea floor or below the sea floor. The conventional submarine cable search technology is a magnetic detection method that locates the optical submarine cable by superimposing a low-frequency alternating current on the current supplied to the submarine repeater and detecting the AC magnetic field generated in the optical submarine cable. It has been known.

First, an outline of an optical submarine cable system will be described with reference to FIG. The optical submarine cable 1 is formed by coating an optical fiber 2 for transmitting an optical signal and a power supply conductor 3 for supplying power. The optical submarine cable 1 is provided with optical submarine repeaters 4 at regular intervals. This optical submarine repeater 4
1 operates by receiving power from the power supply conductor 3 and amplifies an optical signal transmitted through the optical fiber 2 to compensate for transmission loss. The end of the optical submarine cable 1 is connected to a landing station 5.

The landing station 5 has an optical terminal equipment (OLT).
In addition to 6, a power supply device 7 for applying a power supply current to the power supply conductor 3 of the optical submarine cable 1 is provided. The supply current is a DC current for supplying power to each optical submarine repeater 4. The power supply device 7 is provided with an AC oscillator 8 for superimposing a low-frequency AC signal component on a power supply current.

At the time of the magnetic search, the landing station 5 operates the AC oscillator 8 to superimpose a low-frequency AC signal component on the feed current (see FIG. 2). An AC magnetic field 9 is generated near the optical submarine cable 1 by the AC signal component. Therefore, the magnetic sensor 11 is suspended from the repair ship 10 in the sea, and the position of the optical submarine cable 1 is located by detecting the AC magnetic field 9 described above.

[0006] When searching for a submarine cable, there is also provided a method of applying a DC current in a direction opposite to the feed current to a feed conductor and superimposing a low-frequency AC signal on the DC current ("Research on International Communications"). , No. 112, April 1982, p102-114). FIG. 4 shows the conduction current of the power supply conductor at this time. Note that the repeater basic circuit described in FIG. 2 on page 104 of the same document has a monitor signal generation circuit (SV OSC), but this monitor signal generation circuit is not involved in magnetic search. Instead, by outputting a specific frequency signal in the transmission band to the analog transmission line, it is used for monitoring the state of the submarine cable and submarine repeater on the landing station side.

[0007]

In the above prior art, the amplitude of the AC signal component cannot be made very large, considering the effect on the reliability of the power supply of each optical submarine repeater 4, and the AC signal component cannot be increased. However, since the optical submarine cable 1 and the optical submarine repeater 4 have a large attenuation, there is a problem that a section where the magnetic search can be performed is limited to a section at a fixed distance from the landing station. This problem becomes more pronounced when applied to a long-haul optical submarine cable system. For sections that exceed the searchable distance, the failure section is estimated by electrical tests and optical tests, and the cable position is further estimated based on the laying work records, and bottoming with a search anchor is performed by trial and error. Therefore, it is necessary to take a method such as capturing the cable. According to this method, not only the working efficiency becomes extremely poor, but also a problem arises in that the normal portion of the optical submarine cable may be damaged by the search anchor.

On the other hand, according to the technique described in the above-mentioned document, it is possible to extend the searchable distance by suppressing the attenuation in the optical submarine repeater by reversing the direction of the current. However, in this case, since the attenuation of the AC signal component due to the impedance of the optical submarine cable cannot be avoided, there is a limit even though the searchable distance from the landing station is slightly extended. In addition, at the time of the magnetic search, a reverse current is conducted to the power supply conductor 3, so that a reverse bias is applied to the optical submarine repeater, the optical amplification operation is not maintained, and it is impossible to continue the communication service. It becomes possible. Further, there is a concern that application of the reverse current may adversely affect optical submarine repeater components. Therefore, an object of the present invention is to provide a magnetic search technology capable of searching an arbitrary section without applying a reverse current to a power supply conductor.

[0009]

An optical submarine cable system according to a first aspect of the present invention comprises a plurality of optical submarine repeaters installed at predetermined intervals and a feed conductor for supplying a direct current to the plurality of optical submarine repeaters. An optical submarine cable system, comprising: an optical submarine cable provided with the optical submarine cable; and a power supply device installed at a terminal of the optical submarine cable and applying a DC current to the power supply conductor. An AC oscillator that superimposes the AC signal on the DC current is installed in a predetermined optical submarine repeater, and the interval between the optical submarine repeaters where the AC oscillator is installed is such that all of the AC oscillators oscillate the AC signal. Then, the AC magnetic field generated in the vicinity of the optical submarine cable does not reach an intensity below the detection limit level of the magnetic sensor for optical submarine cable search along the entire area of the optical submarine cable. Septum is.

According to such an optical submarine cable system,
An AC oscillator is previously arranged on the optical submarine cable, and at the time of the search, the AC oscillator located at a position close to the suspension section of the optical submarine cable or all the AC oscillators perform an oscillating operation. As a result, an AC signal component is superimposed on the DC current flowing through the power supply conductor, and an AC magnetic field is generated near the optical submarine cable in a section where the AC signal component is transmitted through the power supply conductor. That is, within a certain distance from the installation position of the AC oscillator, an AC magnetic field of effective strength can be obtained regardless of the distance from the landing station. By detecting the AC magnetic field, a magnetic search of the optical submarine cable is performed.

An optical submarine cable system according to a second aspect of the present invention includes a control device for outputting a control instruction to an arbitrary AC oscillator. An AC oscillator attached to at least a predetermined number of optical submarine repeaters operates in accordance with the control instruction, applies an AC output to a power supply conductor, and superimposes an AC signal component on the DC current for powering the repeater.

According to such an optical submarine cable system,
Centralized control of each AC oscillator by the controller,
For example, at the time of a magnetic search, it is possible to control such that only an AC oscillator located near the suspension section performs an oscillation operation. The control instruction from the remote controller to each AC oscillator may be in the form of, for example, an optical signal and transmitted using an optical fiber of an optical submarine cable.

In the optical submarine cable system according to the third aspect, the AC oscillator attached to at least a predetermined number of optical submarine repeaters operates steadily and applies an AC output to the power supply conductor to supply power to the repeater. It superimposes an AC signal component on a DC current.

According to such an optical submarine cable system,
The constant operation of each AC oscillator eliminates the need for remote control means for externally controlling the AC oscillator and communication means between the AC oscillator and the AC oscillator.・ Since the off-switching function is not required, the system can be simplified. In this case, care should be taken to suppress the output level of the AC oscillator to the extent that the reliability of power supply to the optical submarine repeater is not significantly deteriorated.

In the optical submarine cable system according to the present invention, the output level of the AC oscillator is such that the maximum value and the minimum value of the pulsating current after the superposition of the AC signal component are within the range of the rated value of the DC current.

According to such an optical submarine cable system,
Since the output level of the AC oscillator is set sufficiently lower than the power supply current level, power can be continuously supplied to each optical submarine repeater even during magnetic search, and communication services can be continued. Becomes possible.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments.

The outline of a long-distance optical submarine cable system according to this embodiment will be described with reference to FIG. In FIG. 1, an optical submarine cable 1 includes an optical fiber 2 for transmitting an optical signal.
And a power supply conductor 3 for supplying power. A direct current for feeding power to the repeater (hereinafter referred to as a feed current) is applied to the feed conductor 3.

In this optical submarine cable 1, optical submarine repeaters 4 are arranged at regular intervals. The optical submarine repeater 4 operates by receiving power from the power supply conductor 3 and amplifies an optical signal transmitted through the optical fiber 2 to compensate for transmission loss. Each optical submarine repeater 4 has 4-1 and 4-
.., 4-6, and the sections between the optical submarine repeaters 4 of the optical submarine cable 1 are similarly 1-1, 1-2,.
Is assigned.

An AC oscillator 12 is added to each of the optical submarine repeaters 4-1, 4-3, and 4-5. The AC oscillator 12 performs an oscillating operation according to a control signal described later, and applies a low-frequency AC output to the power supply conductor 3. Due to the application of the AC output, as shown in FIG. 2, the feed current becomes a pulsating current on which the AC signal component is superimposed. The frequency of the AC signal component is desirably set in the range of about 10 to 50 Hz in consideration of both reduction of transmission loss and improvement of noise resistance. Each AC oscillator 12 is denoted by reference numerals 12-1, 12-3, and 12-5 from the left side in the figure.

In this example, a mode in which an AC oscillator 12 is added to every other optical submarine repeater 4 is shown.
An appropriate installation interval depends on a searchable distance, which will be described later. Depending on the searchable distance, every few or all of the optical submarine repeaters 4 are selected and an AC oscillator 12 is selected.
May be added.

An end of the optical submarine cable 1 is connected to a landing station 5. In the landing station 5, the optical terminal device 6 includes:
It transmits and receives optical signals via the optical fiber 2.
The power supply device 7 applies a power supply current to the power supply conductor 3. The level of the power supply current is appropriately set according to the number of optical submarine repeaters 4 installed and other design matters.
The remote control device 13 is for remotely controlling each AC oscillator 12. If the control signal is transmitted from the remote control device 13 to the AC oscillator 12 by an optical transmission method, the optical fiber 2 can be used as a transmission path. Also,
At least an oscillation operation start instruction signal and an oscillation operation end instruction signal are set as control signals. In addition, the AC oscillator 8 conventionally attached to the power supply device 7 (see FIG. 3).
Can be omitted in this example.

Next, a magnetic tracing method in the optical submarine cable system will be briefly described. Optical submarine cable 1
In the case where a disconnection fault has occurred, the fault section is first estimated by a known electrical test or optical test. As a result, a faulty section can be specified up to a section adjacent to any one of the optical submarine repeaters. Here, the section 1-6 is a section where a water contact point (hereinafter referred to as a fault point) due to a disconnection accident has occurred, and the sections 1-5 and 1-6 adjacent to the optical submarine repeater 4-5.
Is an estimated obstacle section.

Thereafter, a fault point is located by a magnetic search line. That is, first, the remote control device 13 outputs an oscillation operation start instruction signal to the AC oscillator 12-5.
Upon detecting this start instruction signal, AC oscillator 12-5 starts an oscillating operation. As a result, an AC signal component is superimposed on the feed current flowing through the feed conductor 3, and an AC magnetic field is generated near the optical submarine cable 1.

The relationship between the AC magnetic field strength generated in the optical submarine cable 1 and the cable distance is shown in the lower part (graph) of FIG. As shown in the figure, as the distance from the AC oscillator 12-5 increases, the AC magnetic field intensity attenuates due to the impedance of the optical submarine cable 1 and the optical submarine repeater 4. For the magnetic probe, the AC magnetic field intensity is the detection limit level L of the magnetic sensor 11.
It is possible in the range above 0. The searchable distance is determined by factors such as the amount of cable attenuation in one relay section and the output level of the AC oscillator 12. Therefore, by appropriately setting these factors in consideration of design requirements, it is possible to set the searchable distance with a certain degree of freedom. Also, at the point of failure, the AC magnetic field strength drops significantly, and falls far below the detection limit level L0. Therefore, a failure point can be located by detecting a place where the AC magnetic field is not detected.

Returning to the upper part of FIG.
At 0, the starting position of the section 1-5, that is, the position of the optical submarine repeater 4-5, is estimated based on the record of the laying work and the like, and the magnetic sensor 11 is suspended under the sea and a magnetic probe is located near the estimated position. I do. The position of the cable is located by detecting the above-mentioned AC magnetic field by the magnetic search line. When the cable position is confirmed, the repair ship 10 is moved along the optical submarine cable 1 and tracks the optical submarine cable 1 over the sections 1-5 and 1-6. As a result, when a point where no AC magnetic field is detected is detected, the point is recognized as a failure point. Thereafter, the remote control device 13 outputs an oscillation operation end instruction signal to the AC oscillator 12-5, and upon receiving the end instruction signal, the AC oscillator 12 ends the oscillation operation.

Here, the output level of the AC oscillator 12 is set sufficiently smaller than the power supply current level so that the reliability of the power supply of each optical submarine repeater 4 is not significantly deteriorated, so that the Even if it does, the power supply to each optical submarine repeater 4 can be continued. In this case, it is desirable that the output level of the AC oscillator 12 be suppressed to such an extent that the maximum value and the minimum value of the pulsating current after the superposition of the AC signal component fall within the range of the rated value of the supply current. In this embodiment, the searchable range of one AC oscillator 12 may be small. For example, in the case where the AC oscillator 12 is added to each optical submarine repeater 4, the range in which each AC oscillator 12 is responsible may be a range extending over a 1/2 section before and after. Therefore, the output level of the AC oscillator 12 can be easily reduced.

With the magnetic search technology described in the above-mentioned conventional document, continuation of communication service is impossible.
According to this aspect, a stable power supply can be maintained even during the magnetic search as described above, so that communication service can be continued. In addition, it is possible to avoid a possibility that the application of the reverse current may cause adverse effects on the components of the repeater internal circuit.

The embodiment of the present invention has been described above.
If the output level of the AC oscillator 12 is set to be sufficiently small as compared with the power supply current level as described above,
A mode in which the AC oscillator 12 steadily oscillates is also possible. In this case, not only advantages such as the continuation of the communication service described above can be obtained, but also an advantage that a remote control function of each AC oscillator is not required. That is, while the remote control device 13 can be omitted on the landing station 8 side,
The control signal detection function can be omitted on each AC oscillator 12 side.
Moreover, it is not necessary to secure a transmission path between the AC oscillator 12 and the remote control device 13 on the optical transmission path constituted by the optical fiber 2. In addition, since the control of the AC oscillator 12 on the landing station 5 side is not required at the time of the magnetic search, the magnetic search can be performed by the repair ship 10 alone. Therefore, the communication work between the repair ship 10 and the landing station 5 becomes unnecessary, and the waiting time for the cooperative work between them is eliminated, and the efficiency of the magnetic search operation is improved.

[0030]

As described above, according to the optical submarine cable system according to the first aspect, the AC oscillator is previously arranged on the optical submarine cable, and at the time of searching, a position close to the suspended section of the optical submarine cable. Or all the AC oscillators perform the oscillating operation. As a result, an AC signal component is superimposed on the DC current flowing through the power supply conductor, and an AC magnetic field is generated near the optical submarine cable in a section where the AC signal component is transmitted through the power supply conductor. Therefore, the following effects are obtained in the optical submarine cable system. (1) Regardless of the distance from the landing station, magnetic search can be performed in a section near the AC oscillator. Therefore, even in the case of exploring a section far from the landing station, it is not necessary to perform the bottom pulling operation, and it is possible to avoid a decrease in work efficiency and a possibility of cable breakage due to the work. (2) Since it is not necessary to apply a direct current in the reverse direction to the power supply conductor at the time of the magnetic search, the power supply to the optical submarine repeater can be continued, and the communication service can be continued. The adverse effect on the components of the submarine repeater can be avoided. (3) With a simple improvement such as replacing the existing optical submarine repeater with a device equipped with an AC oscillator, application to an existing optical submarine cable system becomes possible.

Further, according to the optical submarine cable system according to the second aspect, the AC oscillator in the optical submarine repeater can be arbitrarily controlled from the outside, and the light in the vicinity of the section to be subjected to the magnetic search can be controlled. Since only the submarine repeater can be selected and the oscillation operation can be performed only at the time of the magnetic search, the following effects can be obtained. (1) Since the AC oscillator does not need to be operated unnecessarily, the efficiency of the system in terms of power consumption is improved. (2) Instability of the power supply due to the oscillation operation of the AC oscillator can be suppressed to a minimum section and a minimum period, and the power supply reliability of the system is improved.

Further, according to the optical submarine system according to the third aspect, the AC magnet required for the magnetic search is generated by operating each AC oscillator constantly, so that the following effect is obtained. Play. (1) The configuration of the system is simplified. In other words, there is no need for remote control means for externally controlling the AC oscillator or communication means between the means and the AC oscillator. Also, the function of switching on / off the oscillation operation in the AC oscillator becomes unnecessary. (2) Since remote control of the AC oscillator is not required at the time of the magnetic search, the magnetic search can be performed by the repair ship alone, and communication work between the repair ship and the remote control means becomes unnecessary. For example, the magnetic search operation is simplified. Further, the waiting time for coordinating the two operations is not required, so that the efficiency of the magnetic search operation is improved.

In the optical submarine cable system according to the present invention, the output level of the AC oscillator is such that the maximum value and the minimum value of the pulsating current after the AC signal component is superimposed are within the range of the rated value of the DC current. Since the output level is set sufficiently lower than the power supply current level, power can be continuously supplied to each optical submarine repeater even during magnetic search, and communication service can be stably continued. it can.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a magnetic searching method in an optical submarine cable system according to one embodiment of the present invention.

FIG. 2 is a waveform diagram showing superposition of an AC signal component on a supply current in the system of FIG. 1;

FIG. 3 is a conceptual diagram of a magnetic searching method in a conventional optical submarine cable system.

FIG. 4 is a waveform diagram showing a current applied to a power supply conductor during a magnetic search in a conventional optical submarine cable system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical submarine cable 2 ... Optical fiber 3 ... Feeding conductor 4 ... Optical submarine repeater 5 ... Landing station 6 ... Optical terminal equipment 7 ... Feeding device 9 ... AC magnetism 10 ... Repair ship 11 ... Magnetic sensor 12 ... AC oscillator 13 Remote control device

Claims (4)

(57) [Claims] 1. A plurality of optical submarine repeaters installed at predetermined intervals
Feeder for supplying DC current to the optical submarine repeater and the plurality of optical submarine repeaters
Optical submarine cable with body and terminal station of the optical submarine cable
Power supply device installed in the power supply and applying a direct current to the power supply conductor
An optical submarine cable system comprising:
An AC oscillator that superimposes an AC signal on the DC current has a predetermined
Installed in the optical submarine repeater, the interval between the optical submarine repeaters in which the AC oscillator is installed
All of the AC oscillators oscillated the AC signal
When the AC magnetic field generated near the optical submarine cable is
Magnet for optical submarine cable tracing along the entire optical submarine cable
Interval that does not reach intensity below the sensor's detection limit level
An optical submarine cable system, characterized in that: 2. An AC signal is oscillated from an arbitrary AC oscillator.
2. The optical device according to claim 1, wherein the control device is installed at the terminal station.
Submarine cable system. 3. The AC oscillator steadily oscillates an AC signal.
The optical submarine cable system according to claim 1, wherein 4. The output level of the AC oscillator is the AC signal.
The maximum value and the minimum value of the pulsating flow after the component superposition are determined by the DC current.
The light seabed according to claim 1, 2 or 3, which is within a range of a rating.
Cable system.