JPS6153581A - Position monitor for submarine cable or the like - Google Patents

Abstract

PURPOSE:To achieve avoidance of damage and accurate installation of a cable, by mounting corner reflectors with a better reflection efficiency for ultrasonic waves discretely on the cable to enable the capturing of the position and attitude thereof during and after the installation thereof. CONSTITUTION:This apparatus is equipped with ultrasonic wave reflection bodies 5 mounted discretely on a submarine cable 4, an ultrasonic wave transmitter and an ultrasonic wave receiver arranged on a cable installation ship 1 or a monitor ship 2 and an analysis recorder 3 of received signals. The reflection bodies 5 are each made up of a corner reflector section 5-1 for sending reflected waves in the direction of incoming ultrasonic waves, a buoyance generating section 5-2 and a mounting section 6 for a cable. The corner reflector section 5-1 is so set that the opening thereof is vertical to the sea surface by a buoyance with the buoyance generator section 5-2 while mounted on the cable at intervals of several m - several ten m.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to an underwater ultrasonic device that reliably determines the position of submarine cables and the like during or after installation, from shallow waters to deep waters.

(Problems with Prior Art) Conventionally, various methods have been proposed for location detection of underwater objects. When the target is large, the general method is to directly capture the reflection of the ultrasound, and for small targets, deep seas, or long distance targets, an ultrasonic oscillator (so-called binger or transponder) is used. ) and receive the signal at sea to determine its position.

The submarine cable has a diameter of 25cm (submarine optical cable) or a diameter of 44I+J for deep seas of 1000 to 1500m or more.
(submarine coaxial cable) is used, and various armored cables that are used for shallower applications of 1000 m or less have a diameter of approximately 100 m.
It has a small diameter of less than +u. In order to directly irradiate ultrasonic waves onto these small diameter cables and capture the reflected waves to determine the position of the cable, a short wavelength approximately equal to or less than the cable diameter is used, and the cylindrical shape and inefficient reflection characteristics are used. There are many limitations, such as the need to irradiate ultrasonic waves with sufficient energy while taking into account the attenuation characteristics of the ocean. In reality, there is an example in which the location of a submarine cable was investigated using the above method.
There are only examples of experiments at extremely short distances of ~ several tens of meters;
It is extremely difficult to explore deep seabed cables over 1,000m deep from the sea surface.

A second method is to attach an ultrasonic oscillator to the cable. In principle, this method works at a depth of several thousand meters.
It is possible to sufficiently capture the cable position even in deep sea areas. However, in order to know the location of long-distance submarine cables, sometimes numbering in the thousands, a large number of the ultrasonic oscillators are required.

These are deep-sea specifications and are expensive, ranging from a few yen to over a million yen per unit, and the lifespan of the installed batteries is also limited. Therefore,
Although it would be economical to recover the waste after it has been laid, many problems can be expected in the design of the mechanism and the establishment of construction methods.

(Object of the Invention) In order to eliminate these drawbacks, the present invention has provided corner reflectors that are highly efficient in reflecting ultrasonic waves and are extremely inexpensive and are discretely attached to the cable, and the ultrasonic wave transmitting/receiving device mounted on a ship on the sea is used to detect the corners. The present invention provides a position monitoring device for a 7+ submarine cable, etc., which can capture the position of a reflector.

(Structure and operation of the invention) The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a conceptual diagram of an embodiment of the present invention, where 2 is a submarine cable laying ship, 2 is a monitoring ship, 3 is an ultrasonic transceiver,
4 is a submarine cable, 5 is an ultrasonic corner reflector, 6 is
7 is the outgoing path of the ultrasonic wave from the ultrasonic wave transmitting/receiving device 3, and 8 is the incoming path. FIG. 2 shows an example of the structure of the corner reflector section 5, where 5-■ is a reflecting plate and 5-2 is a buoyancy generating section.

With this structure, the corner reflector always maintains its attitude in the direction of buoyancy, that is, in the direction perpendicular to the sea surface, and as a result, it can efficiently reflect ultrasonic waves in the direction of incoming waves over a wide range. W, broken line 7a in Figure 2,
8a and 8a and 7b and 8b illustrate the paths of the ultrasonic waves incident on the corner reflector and the ultrasonic waves reflected from the corner reflector on only two sides.

With this structure, the corner reflector can be manufactured extremely simply and at low cost by combining simple circular plates at right angles. Reflector plate 5 of corner reflector 5
-1 is made of acoustic impedance (Z
, ) is sufficiently larger or smaller than that of seawater (Z2). Ultrasonic reflectance (R)
For (k7/m2・s), for example, z+(air)×4
x102 (kz/m2・s), Zl (steel)
#45 x 10'(k7/m's).

Z, (rubber)';1.3X10'(kp/m's). R (seawater/air) dust is 99.95%, R (seawater/steel) is 93.5%, R (seawater/rubber) is 1%, etc. Therefore, when selecting a reflective material, materials with air bubbles inside, such as styrene foam and urethane foam, are promising when the water depth is shallow. If there is a risk that a button or a material with bubbles inside as described above may be crushed due to the deep water depth, it is necessary to select a solid material such as steel. Here, since styrene foam, urethane foam, etc. have buoyancy themselves, there is no need to provide a special buoyancy generating section.

If a solid material such as metal is used, a buoyant body such as 5-2 in FIG. 2 is required. For this purpose, a buoyancy material for deep depths in which fine hollow glass spheres (20 to 80 μmφ) are fixed and molded with epoxy 7 resin can be used.

Next, as an apparatus for transmitting, receiving, analyzing, and recording ultrasonic signals, an existing sonar system (for example, a scanning nonar, a multibeam sonar, and a side run king sonar) can be used. All of these are objects within the measurement field of view (for example, the seafloor surface).

Distribution of ultrasonic reflection intensity of floating objects in the sea, etc.) and its position (
(distance, direction)/stem.

Therefore, the corner reflector has sufficiently large ultrasonic reflection characteristics compared to the background surface of the ocean floor, etc.
Its position can be determined by these/stem.

FIG. 3 shows another embodiment of the present invention, which is a second corner reflector installed adjacent to the 5a corner reflector 5 at an interval of, for example, several meters to several tens of meters. Two or three of them form a group, and are separated by a sufficient distance, for example, 100 m or more, from an adjacent flafter group.

When reflectors are attached to the cable in this arrangement, the following advantages can be expected when grasping the position and posture of the cable.

(1) By having two or more almost identical specific ultrasonic reflection reactions appear on the screen of the onboard monitoring device at almost the same time, it is possible to more reliably detect ultrasonic waves from the reflector than when a single reflector exists. It can be determined that the reaction is −
In other words, even if something that shows a reaction similar to the reflector reaction is captured by chance, such as a rock or a piece of a shipwreck, it can be distinguished.

(2) From the arrangement of each glue reflector in the reflector group,
The longitudinal direction of the cable can be roughly predicted. Therefore, in practice, it is unnecessary and economical to closely attach a large number of glue flapers to the cable at equal intervals.

(Effects of the Invention) As explained above, since the position and posture of submarine cables can be captured during or after installation, the following effects can be expected.

(1) Fishing school detectors installed on general fishing boats, etc.

Since the position of the submarine cable can be determined using a depth sounder, etc., it has the great advantage of avoiding damage to the submarine cable caused by trawling or anchoring.

□ (2) Cable sinking state during cable installation 1 By understanding the bottom position, the cable installation conditions from the ship can be clarified. As a result, it is possible to accurately lay the cables on the planned route without excess or deficiency. This makes it possible to (1) save cable length, (reduce residual tension in the ITL cable, and (iii) avoid cable suspension, etc.).

(3) Since the bottom position of the cable can be accurately grasped, the positional accuracy of the probe line during repair is improved. As a result, the number of cables and repeaters to be prepared for troubleshooting can be kept to a minimum. Furthermore, the time and cost required for the search line can be reduced. Therefore, the economical efficiency of fault repair can be greatly improved, and the time required for repair can also be shortened.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of an embodiment of the present invention, FIG. 2 is a perspective view showing an example of the structure of a corner reflector used in the present invention, and FIG.
The figure is a conceptual diagram of another embodiment of the present invention. 1... Submarine cable laying ship, 2... Surveillance ship, 3
... Ultrasonic transceiver device, 4... Submarine cable,
5... Corner reflector for ultrasonic waves, 6... Mounting part, 7... Outgoing path of ultrasonic waves, 8...
Return path of ultrasonic waves, 5-1...Reflector, 5-2...
Buoyancy generating part.

Claims (2)

[Claims] (1) Having ultrasonic reflecting objects discretely attached to a submarine cable, etc., and an ultrasonic transmitting device, a receiving device, and a received signal analysis and recording device disposed on a laying ship or a monitoring ship for the submarine cable, etc., The ultrasonic reflecting object is composed of a corner reflector section that sends reflected waves in the direction of the incoming ultrasonic wave, a buoyant force generating section, and an attachment section for a cable, etc., and the corner reflector section has an opening direction that is changed by the buoyancy of the buoyant force generating section. A position monitoring device for submarine cables, etc., characterized by being set perpendicular to the sea surface. (2) The corner reflector section includes a plurality of corner reflectors attached to the cable in close proximity to each other at intervals of several meters to several tens of meters, and is composed of the plurality of corner reflectors attached in close proximity to each other. 2. A position monitoring device for a submarine cable or the like according to claim 1, wherein the reflector groups are attached to the cable at a sufficiently long distance from each other.