JP2003270358A - Snow accumulation sensor using optical fiber, snow gauge, and snow accumulation measurement method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure a snow accumulation amount by means of a sensor using no electrical component. <P>SOLUTION: This snow accumulation sensor 10 is constructed by spirally winding an optical fiber 2 around a supporting member 1. In the longitudinal direction of the optical fiber 2, a temperature is changed in a position 12 matching a boundary face 5 between the snow 3 and the air 4, and in the position 21, a deflection having a temperature change and linearity is generated. When a light pulse from a light pulse tester 8 is incident on one end of the optical fiber 2, a wavelength of backscattered radiation is shifted in proportion to the deflection amount. Therefore, the backscattered radiation is measured by radiating light pulse from the light pulse tester 8 to the optical fiber 2, and from the temperature change position 12 and a parameter of the spiral shape part, a snow accumulation amount is computed by a signal processing device 9. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for measuring the amount of snowfall using an optical fiber, and more particularly to a snowfall sensor, a snowfall meter and a snowfall measurement method.

[0002]

2. Description of the Related Art Conventionally, the amount of snow is measured by an electric sensor using infrared rays or ultrasonic waves.

[0003]

When the amount of snow is measured using an electric sensor, there are the following problems. (1) It is easily affected by external factors such as weather and high-voltage power lines, and is weak. (2) Costly. (3) When performing multipoint measurement, the snow cover measurement system becomes complicated. (4) A power supply is required for each sensor.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a technique capable of measuring the amount of snow covered by using an optical fiber without using an electric sensor. .

[0005]

The first to fifth inventions are snow sensor using an optical fiber, the sixth invention is a snow meter using an optical fiber, and the seventh invention is an optical fiber. It is a snow measurement method.

A snow accumulation sensor according to a first aspect of the present invention comprises a support member and an optical fiber vertically supported by the support member in a spiral or linear shape. The optical fiber is used for measuring snow accumulation. It is characterized in that it is connected to an optical pulse tester. A second invention is characterized in that, in the snow accumulation sensor according to the first invention, the support member is rod-shaped, and the optical fiber is spirally wound around the support member. A third invention is characterized in that, in the snow accumulation sensor of the first invention or the second invention, the thermal conductivity of the support member is lower than the thermal conductivity of the optical fiber. A fourth invention is characterized in that, in the snow accumulation sensor according to any one of the first invention to the third invention, the optical fiber is coated with a material having a different thermal conductivity at regular intervals. A fifth invention is characterized in that, in the snow accumulation sensor according to any of the first invention to the fourth invention, a material for preventing adhesion of snow and ice is applied to an outer surface of the optical fiber.

A snow meter of a sixth invention comprises a snow sensor according to any of the first to fifth inventions, an optical pulse tester connected to one end of the optical fiber of the snow sensor, and the optical pulse tester. And a signal processing device connected thereto, wherein the optical pulse tester inputs an optical pulse to the optical fiber, receives Brillouin scattered light or Raman scattered light, and measures information related to temperature distribution in the optical fiber. However, the signal processing device is configured to calculate the snowfall amount from the information related to the temperature distribution.

In the snow cover measuring method of the seventh invention, an optical fiber having a spiral or linear shape is vertically arranged at a snow cover measuring point, and an optical pulse tester applies an optical pulse to one end of the optical fiber. It is characterized in that the incident light is used to obtain information related to the temperature distribution in the optical fiber, and the amount of snow is calculated from the information related to the temperature distribution.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the construction of a snow sensor and snow gauge according to an embodiment of the present invention. In FIG. 1, 1 is a support member, 2 is an optical fiber, 3 is in snow, 4 is in the air, 5 is a boundary surface, 6 is a coating (high thermal conductivity), 7 is a coating (low thermal conductivity), and 8 is light. A pulse tester, 9 is a signal processing device, 10 is a snow sensor, 11 is a snow meter, 12 is a temperature change position, 13
Indicates paint (prevention of snow and ice adhesion).

The snow sensor 10 is mainly composed of the support member 1.
And the optical fiber 2. In the example shown in FIG. 1, the support member 1 has a rod shape, and the optical fiber 2 is wound around the support member 1 in a spiral shape in the vertical direction.
Supports vertically. The snow cover sensor 10 is built by arranging the spiral portion of the optical fiber 2 in the vertical direction (usually vertical) at the measurement target point of the snow cover amount. Optical fiber 2
Is connected to the optical pulse tester 8. In FIG. 1, the upper side of the spiral portion is connected to the optical pulse tester 8, but the side connected to the optical pulse tester 8 may be either the upper side or the lower side of the spiral portion.

The snow cover meter 11 comprises a snow cover sensor 10, an optical pulse tester 8 and a signal processing device 9. The optical pulse tester 8 is configured to inject an optical pulse into the optical fiber 2 and measure information related to the backscattered light distribution from the optical fiber 2. The signal processing device 9 is an optical pulse tester 8
And is configured to calculate the amount of snow from the information related to the temperature distribution in the optical fiber 2 measured by the optical pulse tester 8.

Here, the principle of snowfall measurement using the optical fiber 2 will be described. Regarding the temperature distribution in the longitudinal direction of the optical fiber 2, the temperature changes at the position 12 corresponding to the boundary surface 5 between the snow 3 and the air 4. The reason is that the temperature in snow 3 is higher than in air 4 during snowfall, and the temperature in air 4 is higher than in air 3 during snowmelt. Because they are different.

Therefore, by measuring the information relating to the temperature distribution in the optical fiber 2, the temperature change position (the position where the temperature changes in the longitudinal direction) 12 in the optical fiber 2 is measured.
You can know.

Then, by using the known shape parameters of the spiral portion of the optical fiber 2 (for example, the pitch of the spiral, the radius (or diameter) of the spiral, the lower end position of the optical fiber, etc.), the boundary from the temperature change position 12 can be calculated. The height of the surface 5, that is, the amount of snow can be calculated. For example, the temperature change position 12 is usually measured as the distance in the longitudinal direction of the optical fiber 2 starting from the optical pulse tester 8 side, so that the optical fiber 2 is tested from the upper side of the spiral portion as shown in FIG. In the case of being connected to the vessel 8, the amount of snow cover may be calculated from the length obtained by subtracting the temperature change position 12 from the total length (known) of the optical fiber 2 and the shape parameter of the spiral portion. On the contrary, when the temperature change position 12 is measured as a longitudinal distance from the tip of the optical fiber 2 (on the side opposite to the optical pulse tester 8), the temperature change position 12 and the spiral portion The amount of snow cover may be calculated from the shape parameters. On the other hand, even when measured as the distance in the longitudinal direction of the optical fiber 2 with the optical pulse tester 8 side as the starting point, the optical fiber 2 is measured from the lower side of the spiral portion, contrary to FIG.
Is connected to the optical pulse tester 8, the length (known) from the optical pulse tester 8 side of the optical fiber 2 to the lower side of the spiral portion is subtracted from the temperature change position 12 and the spiral portion. The amount of snow can be calculated from the shape parameters of. Contrary to FIG. 1, even when the optical fiber 2 is connected to the optical pulse tester 8 from the lower side of the spiral portion, conversely, the temperature change position 12 is the tip of the optical fiber 2 (the optical pulse tester 8 When measured as the distance in the longitudinal direction starting from the (opposite side), the length obtained by subtracting the length from the temperature change position 12 and the optical pulse tester 8 side to the lower side of the spiral portion from the total length of the optical fiber 2 and the spiral. The amount of snowfall can be calculated from the shape parameters of the shaped part.

Information relating to the temperature distribution in the optical fiber 2 can be obtained by the optical pulse tester 8. The reason is that elongation or compression strain occurs in the optical fiber 2 at the temperature change position 12, and the amount of strain has linearity with respect to temperature change, and when an optical pulse is incident on the optical fiber 2. The backscattered light is generated at the strain generation position (that is, the temperature change position 13), and the wavelength shift (or frequency shift) amount is proportional to the strain, and the time from the incidence of the light pulse to the arrival of the backscattered light, The temperature change position (strain generation position) 12 can be measured by the velocity (known) of the optical pulse in the optical fiber 2.

Therefore, the information related to the temperature distribution in the optical fiber 2 is obtained from the information related to the backscattered light distribution, for example, wavelength shift (or frequency shift).
There is not only information but strain information or temperature information itself, and which of them is used by the signal processing device 9 depends on the function of the optical pulse tester 8.

If the measurement output of the optical pulse tester 8 is the wavelength shift (or frequency shift) information of the backscattered light, the signal processing device 9 determines the speed of the light pulse and the time from the incidence of the light pulse to the arrival of the backscattered light. The temperature change position 12 is calculated according to time, and the amount of snow is calculated by using the known shape parameter of the spiral portion of the optical fiber 2.

If the measurement output of the optical pulse tester 8 is strain information, the signal processing device 9 identifies the strain generation position from the strain information and sets it as the temperature change position 12, and the known shape of the spiral portion of the optical fiber 2. Calculate the amount of snowfall by using the parameters.

If the measurement output of the optical pulse tester 8 is the temperature information itself, the signal processing device 9 identifies the temperature change position 12 from the temperature information and uses the known shape parameter of the spiral portion of the optical fiber 2. Therefore, the amount of snow cover is calculated.

In any case, by comparing the threshold value obtained in advance by experiments with the wavelength shift (or frequency shift) amount, the strain amount or the temperature change amount, the boundary between snow 3 and air 4 It may be determined whether or not the temperature change position 12 corresponds to the surface 5.

As the optical pulse tester 8, for example, an optical / loss integrated pulse tester (hereinafter, B-OTDR) can be used. The B-OTDR measures the strain amount by detecting the wavelength shift amount of the Brillouin scattered light that is proportional to the strain (expansion or compression) of the optical fiber 2 incident on the optical fiber 2, and measures the strain generation position ( The temperature change position 12) is measured by the time until the arrival of Brillouin scattered light.

The backscattered light that can be used when measuring the information related to the temperature distribution is Brillouin scattered light and Raman scattered light, and is not limited to B-OTDR, but an optical pulse tester capable of measuring these is used. be able to.

In this example, the optical pulse tester 8 and the signal processing device 9 are separate bodies, but a device having both functions can be used.

As described above, in this example, the optical fiber 2
Is attached to a rod-shaped support member 1 in a spiral shape to form a snow cover sensor 10. An optical pulse tester 8 is connected to one end of the optical fiber 2 to measure backscattered light, and a signal is output from a temperature change position 12 of the optical fiber 2. The following effects can be obtained by calculating the amount of snow covered by the processing device 9. (1) Since the snow sensor 10 uses the optical fiber 2 itself that does not use an operating part or electrical parts as a measuring part, it is not affected by external factors, for example, the influence of induction of lightning, high-voltage wires, etc. It is possible to measure snowfall with high reliability in a severe outdoor environment. (2) Since the snow sensor 10 has the optical fiber 2 wound around the support member 1, it has a simple structure and can be manufactured at low cost. (3) Since one optical fiber 2 constitutes the snow cover sensor 10 and the transmission part to the optical pulse tester 8, the structure of the snow cover measurement system is simplified. Also, remote monitoring is possible,
Further, in the case of multi-point measurement, a configuration in which a plurality of snow cover sensors 10 are arranged in series on one optical fiber 2 can be taken, so that the structure of the snow cover measurement system can be further simplified. This is the optical fiber 2 of the snow cover sensor 10.
Is equivalent to connecting in series. 1 optical fiber 2
Even when a plurality of snow sensors 10 are arranged in series above, individual temperature change positions 12 of the plurality of snow sensors 10 can be measured separately, and the method described in paragraph [0015] is applied to each snow sensor 10. As a result, the amount of snowfall at each snowfall measurement target point where the snowfall sensor 10 is installed can be calculated from the temperature change position 12. (4) The snow sensor 10 does not require a power source (power supply). (5) Operation / maintenance costs such as maintenance can be reduced.

In the present invention, the amount of snow is measured by focusing on the fact that the temperature change position 13 in the optical fiber 2 corresponds to the temperature change of the boundary surface 5 between the snow 3 and the air 4. It is preferable to make the boundary surface 5 and thus the temperature change position 12 as clear as possible. Therefore, the following measures are taken.

First, the optical fiber 2 is fixed at regular intervals.
It is coated with materials with different thermal conductivity. Thereby, the difference between the temperature of the optical fiber 2 in the snow 3 and the temperature of the optical fiber 4 in the air 4 becomes clear. In FIG. 1, of the two types of coatings 6 and 7, coating 6 (portion indicated by thin solid line and broken line) is a coating using a material having high thermal conductivity, and coating 7 (portion indicated by thick solid line and broken line) is It is a coating using a material having a low thermal conductivity. In this example, the coating 7 having a low thermal conductivity is applied once every four spirals, but the invention is not limited to this.

Secondly, the support member 1 is made of a material having a particularly low thermal conductivity. In other words, the thermal conductivity of the support member 1 is at least lower than that of the optical fiber 2. As a result, heat transfer from the support member 1 to the optical fiber 2 can be hindered, and the temperature change position 12 can be prevented from becoming unclear. It should be noted that the above-mentioned relationship of thermal conductivity between the two types of coatings 6 and 7 may be relative, and the coating 6 may have a higher thermal conductivity than that of the optical fiber 2.
It is not always necessary that the thermal conductivity of the coating 7 is higher and the thermal conductivity of the coating 7 is lower.

Thirdly, after the optical fiber 2 is wound around the support member 1, a coating material 13 made of a material such as a super water repellent material which prevents snow and ice from adhering is applied to at least the outer surface of the optical fiber 2. The paint 13 may be applied to the entire snow sensor 10.

Further, in this example, one end of the optical fiber 2 is positioned at the lower end of the support member 1 and one layer is spirally wound around the surface of the support member 2 from bottom to top at a constant pitch. The support member 1 supports the optical fiber 2 in the vertical direction. The other end of the optical fiber 2 is connected to the optical pulse tester 8 for snowfall measurement. As described above, conversely, one end of the optical fiber 2 is positioned near the upper end of the support member 1 and one layer is spirally wound around the surface of the support member 2 from top to bottom at a constant pitch. Then, the optical fiber 2 may be supported in the vertical direction by the support member 1, and the other end of the optical fiber 2 may be connected to the optical pulse tester 8 for snowfall measurement.

Then, a spiral guide groove having a constant pitch is formed on the surface of the support member 1, and the optical fiber 2 is wound around the support member 1 at a constant pitch by utilizing the inside of the guide groove.

In the illustrated snow accumulation sensor 10, the support member 1 has a rod shape with a circular cross section, but the cross sectional shape is not limited in principle, and may be a plate shape or the like.

Although the optical fiber 2 is spirally wound around the support member 1 at a constant pitch, the pitch does not necessarily have to be constant. Since the shape parameter of the spiral portion of the optical fiber 2 is known even if the pitch is not constant, the snow amount can be measured from the temperature change position 12.

Further, the optical fiber 2 may be supported by the supporting member 1 in the vertical direction, and is not limited to spirally winding. For example, the optical fiber 2 can be supported by the support member 1 by forming a linear shape in the vertical direction.

That is, the optical pulse tester 8 is a B-OTD.
When using R (optical / loss integrated pulse tester),
Since the resolution for measuring the temperature change position 12 is about 1 m, the amount of snow can be measured with a resolution much smaller than 1 m by spirally winding the optical fiber 2 around the support member 1.

However, the temperature change position 12 is set to, for example, 10c.
When an optical pulse tester capable of measuring with a resolution as small as about m is used, even if the optical fiber 2 is linear, the amount of snow can be measured with a resolution as small as about 10 cm.

Therefore, even when the two types of coatings 6 and 7 are applied at regular intervals, the intervals can be determined according to the measurement resolution of the temperature change position 12, and the low thermal conductivity can be obtained, for example, once every other spiral. A rate of coating 7 can be applied.

Similarly, even when the optical fiber 2 is linear, two kinds of coatings 6 and 7 can be applied at regular intervals depending on the measurement resolution of the temperature change position 12.

[0039]

As can be seen from the above description, the present invention has the following effects. (1) By not using electrical parts for the snow sensor, it will not be affected by the weather and the operation and maintenance costs for maintenance will be reduced. Moreover, since it is cheap, it is possible to measure more points at the same cost as the conventional one, and it becomes easy to comprehensively understand the snow amount distribution. (2) Further, the snow cover sensor and the transmission unit from the snow cover sensor to the optical pulse tester can be configured with one optical fiber, and the snow cover measurement system can be simplified even in multipoint measurement. (3) The snow sensor does not need a power supply.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

[Explanation of symbols]

1 Support member 2 optical fiber 3 in the snow 4 aerial 5 boundary 6 coating (high thermal conductivity) 7 coating (low thermal conductivity) 8 Optical pulse tester 9 Signal processing device 10 Snow sensor 11 snow gauge 12 Temperature change position 13 Paint (prevention of snow and ice adhesion)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroshi Komatsu             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation F term (reference) 2F014 AA07 AB01 AB02 CA10 FA10

Claims (7)

[Claims] 1. A support member and an optical fiber vertically supported by the support member in a spiral shape or a linear shape, the optical fiber being connected to an optical pulse tester for snow cover measurement. A snow sensor characterized by being processed. 2. The snow sensor according to claim 1, wherein the support member is rod-shaped, and the optical fiber is spirally wound around the support member. 3. The snow accumulation sensor according to claim 1, wherein the thermal conductivity of the support member is lower than the thermal conductivity of the optical fiber. 4. The snow sensor according to any one of claims 1 to 3, wherein the optical fiber is covered with a material having a different thermal conductivity at regular intervals. 5. The snow sensor according to any one of claims 1 to 4, wherein a material that prevents snow and ice from adhering to the outer surface of the optical fiber is applied. 6. The snow accumulation sensor according to claim 1, an optical pulse tester connected to one end of the optical fiber of the snow accumulation sensor, and a signal processing device connected to the optical pulse tester. The optical pulse tester is configured to inject an optical pulse into the optical fiber, receive Brillouin scattered light or Raman scattered light to measure information related to temperature distribution in the optical fiber, and the signal processing device. Is configured to calculate the amount of snow from the information related to the temperature distribution. 7. An optical fiber having a spiral shape or a linear shape is vertically arranged at a snowfall measurement target point, and an optical pulse is input from one end of the optical fiber from an optical pulse tester to the inside of the optical fiber. The method for measuring snowfall, characterized in that the snowfall amount is calculated from the information related to the temperature distribution and the snowfall amount is calculated from the information related to the temperature distribution.