JPH04147105A - Composite leakage coaxial cable - Google Patents

Abstract

PURPOSE:To attain the compatibility of a sensing function and a leakage coaxial cable function by disposing an optical fiber along the axial direction of a leakage coaxial cable, inside or outside it. CONSTITUTION:In this composite leakage coaxial cable A, a fiber housing part 2 for housing the optical fiber is disposed on the sheath part 14 of the leakage coaxial cable 1, and the optical fiber 3 is disposed inside the fiber housing part 2. Therefore, the optical fiber 3 can have mechanical strength, an influence given to the performance of the leakage coaxial cable 1 by the optical fiber 3 can be decreased, and high sensitivity is held without decreasing the detecting performance of the optical fiber 3. Thus, the leakage coaxial cable having the function of the optical fiber sensor of the high sensitivity can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a composite leaky coaxial cable in which an optical fiber is arranged in a leaky coaxial cable.

[Prior Art] Conventionally, as a device related to disaster detection and evacuation guidance in tunnels, underground malls, building premises, etc., disaster detection devices comprising electrical sensors, information transmission means, etc. are generally known. In this disaster detection device, when a fire or earthquake occurs, an electric sensor quickly detects the fire or earthquake, and an information transmission means quickly transmits the detected information to a designated department. .

Furthermore, remote sensing devices using optical fibers themselves as temperature sensors and pressure/sound pressure sensors are also known.

For example, when used as a temperature sensor, if there is a temperature distribution within the optical fiber, the incident light will be scattered by this temperature distribution, causing Rayleigh scattering and Raman scattering. By measuring the magnitude of Rayleigh scattering and Raman scattering,
Temperature distribution can be detected with high sensitivity. In addition, when used as a pressure/sound pressure sensor, the same pressure/sound pressure sensor can be used.
Sound pressure can be detected with high sensitivity. This remote sensing device is a device that has attracted much attention because it has excellent features such as safety, light weight, and small size.

[Problems to be Solved by the Invention] By the way, since the above-mentioned disaster detection device has a configuration in which electrical sensors are placed at each location that requires measurement, it is not possible to select and determine the locations that require measurement in advance. However, there was a drawback that it was not possible to continuously measure objects over long distances. Therefore, if a fire or the like occurs in a location where the electrical sensor is not installed, early detection is difficult and there is a possibility that something serious will happen.

In addition, in remote sensing devices that use light, in order to detect temperature distribution, pressure/sound pressure, etc. with high sensitivity, the diameter of the optical fiber must be extremely thin, and the mechanical strength of the optical fiber must be maintained. The problem was that it was very difficult to do so. In order to maintain mechanical strength, it is sufficient to make the cable thick, but if the cable is made thick, the sensitivity will decrease and the characteristics of the optical fiber sensor will be lost.

The present invention has been made in view of the above circumstances, and provides a composite leaky coaxial cable that effectively solves the above drawbacks and problems, and is also capable of miniaturization, multi-point continuous measurement, and high reliability. It's about doing.

[Means for Solving the Problems] In order to solve the above problems, the present invention employs the following composite leaky coaxial cable. That is, the composite leaky coaxial cable according to claim 1 is characterized in that an optical fiber is disposed inside or outside the leaky coaxial cable along the axial direction of the leaky coaxial cable.

Further, the composite leaky coaxial cable according to claim 2 includes:
The present invention is characterized in that a fiber accommodating portion for accommodating an optical fiber is disposed in the sheath portion of the leaky coaxial cable.

[Function] In the composite leaky coaxial cable according to claim 1 of the present invention,
By arranging an optical fiber inside or outside the leaky coaxial cable along the axial direction of the leaky coaxial cable, the leaky coaxial cable is given the function of an optical fiber.

Further, in the composite leaky coaxial cable according to claim 2, a fiber storage portion is provided at the north portion, which is the outermost periphery of the leaky coaxial cable, so that the optical fiber is protected by this fiber storage portion, and the optical fiber is protected by the fiber storage portion. Since the fiber is placed in the outer sheath of the leaky coaxial cable, it is possible to perform high-performance anomaly detection while maintaining the high sensitivity inherent to optical fiber detectors without reducing detection performance.

[Example 1] An example of the composite leaky coaxial cable according to the present invention will be described below.

First, a composite leaky coaxial cable A according to the present invention will be explained based on FIG. In the figure, reference numeral 1 indicates a leaky coaxial cable, 2 indicates a fiber housing, and 3 indicates an optical fiber.

The leaky coaxial cable 1 is used for mobile radio (communication such as command, control, contact, etc.) in railways, roads, tunnels, underground malls, underground mines, building premises, etc. This leaky coaxial cable 1 is a cable with an outer diameter of 51 mII+, in which each layer of an insulator 12, an outer conductor 13, and a north portion 14 are sequentially formed concentrically on the outer peripheral surface of an inner conductor I+ serving as a central axis.

The internal conductor +1 is a conducting wire made of soft copper wire, aluminum pipe, or the like.

The insulator 12 is made of polyethylene (
PE) A string is spirally wound and the top is covered with a PE film. If heat resistance is required, a track-resistant layer is further formed on the PE layer.

The outer conductor 13 is a conductor in which a layer of laminated aluminum tape is wound around the outer circumferential surface of the insulator 12, slots are provided in the laminated aluminum tape layer, and pleats are attached vertically. When heat resistance is required, no pleats are used.

The north part 14 is for protecting the inner conductor II, the insulator 12, and the outer conductor 13, and is made of polyvinyl chloride resin (PVC).
), etc., with a thickness of 4 □m. A plurality of fiber storage sections 2.2 are embedded in this north section 14.

The fiber storage section 2 is a tube for storing an optical fiber 3, which will be described later, and has, for example, an outer diameter of 2.5 mm and an inner diameter of 1.5 mm. O
mm, made of fiber-reinforced plastic (FRP), with a single layer of synthetic resin such as polyimide adhered to the inner circumferential surface of the tube in the form of a film. In addition to the above-mentioned fiber-reinforced plastics, suitable materials include, for example, carphone fiber-reinforced polyester, polyimide resin, Evokin resin, silicone resin, nylon, and Teflon. The fiber storage section 2 extends linearly along the outer circumferential surface of the outer conductor 13 and is embedded within the sheath section 14 so as not to come into contact with the outer conductor 13. As a method for embedding the fiber storage section 2 in the sheath section 14, extrusion molding is suitably used. This fiber storage section 2 contains an optical fiber 3.
is stored.

The optical fiber 3 is composed of an SM quartz-based or CI quartz-based single mode optical fiber, and utilizes the sensor function of this optical fiber itself, and serves as one component of a detection device to be described later. This optical fiber 3 is coated with a material having a large Young's modulus such as epoxy acrylate or urethane resin.

In this composite leaky coaxial cable A, leaky coaxial cable 1
By disposing the fiber storage part 2.2 in the north part 14 of the cable, the leaky coaxial cable 1 is given the function of an optical fiber, and the fiber storage part 2 protects the optical fiber 3
The influence of this optical fiber 3 on the performance of the leaky coaxial cable l is further reduced. Further, this optical fiber 3 functions as an optical fiber sensor that maintains high sensitivity without reducing detection performance.

As explained in detail above, according to the composite leaky coaxial cable A of the above embodiment, the fiber storage part 2.2 for storing the optical fiber is connected to the sheath part 1 of the leaky coaxial cable l.
4 and the optical fiber 3 is placed inside the fiber housing 2, it is possible to impart mechanical strength to the optical fiber 3, and the influence of this optical fiber 3 on the performance of the leaky coaxial cable l can be reduced. It can be made extremely small, and high sensitivity can be maintained without reducing the detection performance of the optical fiber 3. Therefore, it is possible to provide a leaky coaxial cable that has the function of a highly sensitive optical fiber sensor.

FIG. 2 is a diagram showing a modification of the above-mentioned ventral leakage coaxial cable A.

The structure of this composite leaky coaxial cable B is different from the structure of the above-mentioned combined leaky coaxial cable A, in that the north part 14 has a
A hole for accommodating the optical fiber 3 is formed along the outer circumferential surface of the external conductor 13, and this hole is used as a fiber accommodating portion 21.

This composite leaky coaxial cable B has exactly the same function and effect as the composite leaky coaxial cable A by inserting the optical fiber 3 into the fiber storage section 21. In addition, when the diameter of the optical fiber 3 is relatively small, the fiber storage section 21
The gap between the optical fiber 3 and the optical fiber 3 may be filled with an insulating material.

FIG. 3 is a diagram showing another modification of the above composite leaky coaxial cable A.

The configuration of this composite leaky coaxial cable C is different from the configurations of the composite leaky coaxial cables A and H described above. The optical fiber 3 is embedded and integrated along the outer peripheral surface of the outer conductor 13 inside.

In this composite leaky coaxial cable C, the inner surface of the sheath part 14 in contact with the outer circumferential surface of the optical fiber 3 constitutes a fiber storage part 22, and has exactly the same functions and effects as the composite leaky coaxial cable A.

Next, the composite leaky coaxial cable A (B) of the present invention.

An application example of C) will be explained.

FIG. 4 shows a detection device E using a composite leaky coaxial cable A (B, C).

This detection device E includes the above-mentioned optical fiber 3, light source 31,
It is roughly composed of a detection section 32, a signal processing section 33, a display device 34, and a control device 35, and the light propagating through the optical fiber 3 is affected by the temperature distribution, vibration, pressure change, electric field, magnetic field, etc. inherent in the optical fiber 3. The so-called OTD R utilizes changes in the phase, polarization, loss, scattering, etc. of this light.
(Optical Tia+e Domain Ref
This is a distributed optical fiber sensor using the lecto+netry method. This detection device E detects the phase, polarization, loss, scattering, etc. of light in the optical fiber 3 with high sensitivity and performs signal processing to detect various factors such as temperature, vibration, pressure, sound, electric field, magnetic field, radiation, etc. It measures changes in physical quantities with high precision.

The light source 31 irradiates the optical fiber 3 with repeated pulses of high-power, narrow-pulse-width laser light.
A laser or the like is preferably used.

The detection unit 32 detects with high sensitivity Raman scattered light, Brilliant scattered light, Rayleigh scattered light, and Fresnel reflected light generated in the optical fiber 3 due to the repeated irradiated pulses.

The signal processing unit 33 processes the signal output from the detection unit 32 by
For example, it performs necessary processing such as integration processing on repeated pulses, and outputs the processed data.

The display device 34 displays the measurement data and processing results output from the signal processing section 33, and includes an analog display device,
It consists of a digital display device, an X-Y recorder, etc.

The control device 35 outputs control signals to various devices that require control based on the data output from the signal processing section 33, and performs necessary processing and instructions to other systems.

Next, the effects of the detection bag RE will be explained.

■ For temperature distribution measurement When the light source 31 repeatedly pulses high-output, narrow-pulse-width laser light onto the optical fiber 3A, silicon dioxide (SiO
940nm Stokes light whose frequency has decreased due to thermal vibration, and conversely 870nm whose frequency has increased by the same frequency.
Raman scattering composed of nm anti-Stokes light occurs. The detection unit 32 detects the light intensity of the Stokes light and the anti-Stokes light, the signal processing unit 33 determines the ratio of the Stokes light and the anti-Stokes light, and uses this ratio and a previously determined characteristic table of the backward Raman scattered light. By comparison, the temperature distribution in the length direction in the optical fiber 3 can be determined.

Here, if a part of the optical fiber <3 is suddenly heated due to a fire or abnormal heat generation, a steep temperature distribution will occur in this part of the optical fiber <3, and the light intensity of the anti-Stokes light will change rapidly. do. The detection unit 32 detects an abnormality in the light intensity of the anti-Stokes light, and the signal processing unit 33 determines the ratio of the Stokes light and the anti-Stokes light, thereby detecting changes in the temperature distribution in the length direction in the optical fiber 3 with high sensitivity. And it can be found quickly. From this measurement result, it is possible to know the occurrence of a fire, abnormal heat generation, etc.

(2) In the case of strain distribution measurement, the light source 31 irradiates the tip fiber 3 with repeated pulses of high-power, narrow pulse width laser light to cause Brilliant scattering in the optical fiber 3. Probe pulse light is irradiated from the opposite side in accordance with the frequency of this Brilliant scattered light, and the intensity of the Brilliant scattered light at this time is detected by the detection section 32. Here, if there is a strain distribution in the optical fiber 3, the frequency of the brilliant scattered light changes due to this strain distribution. The detecting section 32 detects the frequency change of the brilliant scattered light, and the signal processing section 33 can determine the magnitude of longitudinal strain in the optical fiber 3 based on the frequency change of the brilliant scattered light.

Here, when an earthquake occurs and strain suddenly occurs in the optical fiber 3, the frequency of the brilliant scattered light changes due to the strain distribution due to the strain in the fiber 3. The detection unit 32 detects the frequency change of the Brilliant scattered light, and the signal processing unit 33 determines the magnitude of longitudinal strain in the end fiber 3 based on the frequency change of the Brilliant scattered light. Strain in the length direction can be determined quickly and with high sensitivity. The occurrence of an earthquake can be determined from this measurement result.

According to this detection device E, the detection section 32 can quickly detect the phase, polarization, loss, scattering, etc. of light in the optical fiber 3 with high sensitivity, and the signal processing section 33 can detect the phase, polarization, loss, scattering, etc. of light in the optical fiber 3.
It is possible to process signals accurately and quickly based on the output of the optical fiber 3, and to determine changes in physical quantities in the length direction in the optical fiber 3 with high sensitivity and quickly, and from this measurement result, it is possible to quickly detect the occurrence of a fire or earthquake. This enables early detection.

[Effects of the Invention] As explained in detail above, according to the composite leaky coaxial cable according to claim 1 of the present invention, an optical fiber is provided inside or outside the leaky coaxial cable along the axial direction of the leaky coaxial cable. , it is possible to provide the leaky coaxial cable with the function of an optical fiber. Therefore, this cable can have both the sensing function and the leaky coaxial cable function.

Further, the composite leaky coaxial cable according to claim 2 may include
Since the fiber storage part for storing the optical fiber is arranged in the sheath part of the leaky coaxial cable, the fiber storage part protects the optical fiber from external impact, and this optical fiber improves the performance of the leaky coaxial cable. The influence can be further reduced. Furthermore, this optical fiber can maintain high sensitivity without reducing detection performance.

As described above, it is possible to provide a composite leaky coaxial cable that is compact, highly reliable, and capable of continuous measurement at multiple points.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a ventral leaky coaxial cable which is an embodiment of the present invention, FIGS. 2 and 3 are cross-sectional views of a composite leaky coaxial cable which is a modification of the present invention, and FIG. 4 is a cross-sectional view of a composite leaky coaxial cable which is a modification of the present invention 1 is a schematic configuration diagram of a detection device that is an application example of a composite leaky coaxial cable. A, B, C...Composite leaky coaxial cable, l...
...Leaky coaxial cable, 2.21.22 ...Fiber storage section, 3.
... Optical fiber, 11 ... Inner conductor, 12 ... Insulator, 13 ... Outer conductor, 14 ...
... Sheath part, E ... Detection device, 31 ... Light source, 32 ... Detection section, 33 ... Signal processing section, 34 ...
... Display device, 35 ... Control equipment.

Claims (2)

[Claims] (1) A composite leaky coaxial cable characterized in that an optical fiber is disposed inside or outside of the leaky coaxial cable along the axial direction of the leaky coaxial cable. (2) The composite leaky coaxial cable according to claim 1, characterized in that a fiber storage section for storing an optical fiber is provided in the sheath section of the leaky coaxial cable.