JP3390907B2 - Light wave phase difference type snow depth automatic measuring method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light wave phase difference type snow depth measuring method and apparatus.

[0002]

2. Description of the Related Art Conventionally, as this type of lightwave phase difference type snow depth measuring method and apparatus, distance measuring light as laser light modulated at a modulation frequency from a light transmitting means is used as a surface to be measured on a snow surface. The light is projected and a part of the irregularly reflected light is received as reflected light by the light detecting means, and the light wave phase difference between the distance measuring light and the reflected light is measured to evaluate and measure the depth of snow on the ground surface. Something like that is proposed.

[0003]

However, in the case of the above-mentioned conventional structure, the snow cover is different from the ground surface, and the distance measuring light projected from the light transmitting means is not immediately reflected on the surface, but once,
It has the property of entering the inside of snow and repeating scattering, and then emitting light after repeating internal scattering.Therefore, a delay phenomenon until the reflected light from the snow surface enters the light detection means inevitably occurs, and the light wave position When measuring the phase difference, when measuring the reference zero position where the height of snow is zero, it is measured on the ground surface of the snow-free surface, whereas it is measured on the snow surface during snowfall. Due to the delay phenomenon, there is a disadvantage that the snow depth may be measured and evaluated to be smaller than the actual snow depth.

[0004]

The present invention is intended to solve such inconvenience, and among the present invention,
According to a first aspect of the present invention, the distance measuring light as the laser light modulated by the modulation frequency is projected from the light transmitting means onto the snow surface as the surface to be measured, and a part of the irregularly reflected light is reflected as the light detecting means. When measuring and measuring the depth of snow on the ground surface by measuring the light wave phase difference between the distance measuring light and the reflected light, the distance measuring light is projected on the ground surface at the position where the distance measuring light is projected. White-colored sponge boards and foams that have a compositional structure similar to that of snow
It is an optical wave phase difference type automatic snow depth measuring method characterized by arranging a reference member made of a styrene plate .

Further, the invention according to claim 2 is a light transmitting means for projecting a distance measuring light as a laser light modulated at a modulation frequency onto a snow surface, and a part of diffusely reflected light from the snow surface is reflected light. As a light detection means, a phase difference measuring means for measuring the light wave phase difference between the distance measuring light and the reflected light, and a phase difference measuring signal output from the phase difference measuring means It is composed of a measuring means for calculating and evaluating the snow depth, and is arranged on the ground surface at the position where the distance measuring light is projected and has a white structure sponge plate or a foamed foam having a composition structure similar to that of snow.
It is an optical wave phase difference type automatic snow depth measuring apparatus characterized by comprising a reference member using a roll plate .

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the device of the present invention, in which 1 is a light transmitting means, which comprises a laser diode 2, its light transmitting unit 3 and a lens 4, and is, for example, 0.6 .mu.m. Distance measuring light L consisting of a red long-wavelength laser
Is arranged so as to project onto a snow surface as the surface M to be measured.

Reference numeral 6 denotes each frequency signal generator, which is connected to a reference oscillator 6 that oscillates an ultrahigh frequency of 1 GHz to 1 MHz, in this case, a modulation frequency of 15 MHz, and transmits the distance measuring light L composed of a long wavelength laser. It cooperates with the unit 3 to perform intensity current modulation at the modulation frequency.

Reference numeral 7 denotes a light detecting means, which comprises a photodiode 8, a light receiving unit 9 thereof, a lens 10, a mixing circuit and an amplifying circuit 11, and reflects a part of irregularly reflected light from the snow surface as the surface M to be measured. It is arranged so as to receive the light R.

Reference numeral 12 denotes a phase difference measuring means, which in this case comprises a lock-in amplifier and a comparator 13 having other structure, and measures the light wave phase difference φ between the distance measuring light L and the reflected light R,
The phase difference measurement voltage signal is output as a voltage.

Here, the operation principle of the light wave phase difference measurement will be described. When the distance measuring light L in which light is modulated by f (m) and λ (m) is emitted, the distance d from the emission point to the measurement point is The following relationships are used between the two.

V = f · λ (m / s) (1) v: speed of wave (light), f: frequency, λ: wavelength d = φ ・ λ / 2π (m) ・ ・ ・ ・ (2) φ; phase difference

2 and 3, the snow depth D _S =
Since there is a relationship of (L ₀ −L ₁ ) · sin θ, snowfall =
The reference zero position L ₀ when ₀ is measured.

Reference numeral 14 is a measuring means, 15 is a calculating means, and 16 is an intermittent measuring means.
Reference numeral 5 is provided with a microcomputer for evaluating and calculating the snow depth on the ground surface K based on the phase difference measurement signal output from the phase difference measuring means 12, and the intermittent measuring means 16
Is the measurement time F or the stop time S for measuring the light wave phase difference φ.
It is equipped with a microcomputer that controls to perform intermittent measurement at intervals of.

In this case, the measuring means 14 and the calculating means 1
5 and the intermittent measuring means 16 measure the five measurement values N by repeating the light transmission or stop a plurality of times, in this case, five times as shown in FIG. 4 at the measurement time F, and measure the five measurement values. With the average value N _av of the three measurement values excluding the maximum value N _max and the minimum value N _min of N, the snow depth with respect to the ground surface K at the measurement time F is measured and evaluated, and the evaluation is performed. It is configured to output a signal.

Q is a reference member, which is arranged on the ground surface K at the position where the distance measuring light L is projected and has a composition structure similar to snow. In this case, for example, it is similar to snow. A white type sponge plate or a styrofoam plate is used. Specifically, as shown in FIG. 5, a reference member Q made of a white type sponge plate is covered with a covering member B made of a transparent synthetic resin such as a polycarbonate resin to prevent it. Formed in a drop structure, the covering member B is fixed to a 25 cm square plate-shaped mounting plate C such as vinyl chloride, the entire thickness is formed to about 25 mm, and the mounting plate C is fixed to the ground surface K. I am configuring.

Since the embodiment of the present invention has the above-mentioned structure, the measuring case E is arranged on the support G standing on the ground surface with a depression angle, and the light transmitting means 1 in the measuring case E changes the modulation frequency. Distance-measuring light L composed of a modulated long-wavelength laser is projected onto the surface of the reference member Q when there is no snow, and onto the snow surface as the measured surface M when there is snow, and these reflected lights R Is received by the light detecting means 7 and is projected onto the surface of the reference member Q when there is no snow, and the distance measuring light L and the reflected light L from the reference member Q when there is no snow.
The phase difference measuring means 12 measures the phase difference measuring means 12 and the measuring means 14 measures the reference zero position where the height of snow is zero. On the other hand, during snowfall, the distance measurement projected on the surface of snowfall. The light L is irregularly reflected on the snow surface as the surface M to be measured, and the reflected light R as a part of the irregularly reflected light is received by the light detecting means 7, and the light wave phase difference φ between the distance measuring light L and the reflected light R is Measured by the phase difference measuring means 12, the measuring means 1
4, the snow depth can be evaluated and calculated on the basis of the reference zero position, and the snow depth can be automatically measured. At this time, the snow depth is projected on the ground surface at the position where the distance measuring light L is projected. Since the reference member Q exhibiting an approximate composition structure is arranged, in the measurement of the reference zero position L ₀ where the snow height is zero in the snow-free state, it is in a state substantially similar to that of measuring the surface of the snow. It can be measured, that is, the light transmitting means 1
The distance measuring light L projected from is not immediately reflected on the surface of the reference member Q, but once enters the inside of the reference member Q and repeats scattering. After repeating internal scattering, the distance measuring light L exhibits the same state as that of the light emitted. As a result, a delay phenomenon occurs until the reflected light from the reference member Q enters the light detection means 7, and the presence of this delay phenomenon causes a reference zero position where the snow height is zero when there is no snow. It is possible to make the measurement conditions for the measurement of the snowfall and the measurement on the surface of the snow during the snowfall almost the same. Therefore, it is evaluated that the snow depth is less than the actual snow depth, It is possible to prevent the occurrence of an erroneous measurement result in which the evaluation is zero, and to improve the accuracy of snow depth measurement.

Further, in this case, since the reference member Q is a white type sponge plate or styrofoam plate similar to snow, the reference member Q can be easily manufactured and installed easily. The workability can be improved.

Further, in this case, the intermittent measuring means 16 performs the measurement of the light wave phase difference φ as the intermittent measurement at intervals of the measurement time F or the stop time S, and at the time of the measurement time F, a plurality of light transmissions. Alternatively, a plurality of measurement values N are measured by repeating the stop, and the average value N _av of the plurality of measurement values excluding the maximum value N _max and the minimum value N _min of the plurality of measurement values N Since the snow depth at the measurement time F is measured and evaluated, it is possible to avoid the influence of disturbance caused by a space floating object consisting of snowflakes, snowflakes, insects, birds, and other foreign matter when measuring this light wave phase difference φ. As a result, the measurement accuracy can be improved and the intermittent snow depth can be efficiently and automatically measured by the intermittent measuring means 16.

The present invention is not limited to the above embodiment, and the circuit structure of the phase difference measuring means 12 is designed by being modified appropriately.

[0020]

As described above, according to the present invention as set forth in claims 1 and 2, the distance-measuring light including the long-wavelength laser modulated by the modulation frequency from the light-transmitting means is used when there is no snow. , Is projected on the surface of the reference member, is projected on the snow surface as the surface to be measured during snowfall, and the reflected light is received by the light detection means, and is projected on the surface of the reference member during no snowfall. Therefore, the light wave phase difference between the distance measuring light and the reflected light from the reference member when there is no snow is measured by the phase difference measuring means, and the reference zero position where the snowfall height is zero is measured by the measuring means. On the other hand, when there is snow,
The distance measuring light projected on the surface of the snow is diffusely reflected by the snow surface as the surface to be measured, and the reflected light R as a part of the irregularly reflected light is received by the light detecting means, and the light waves of the distance measuring light and the reflected light are received. The phase difference is measured by the phase difference measuring means, the measuring means evaluates and calculates the snow depth based on the reference zero position, and the snow depth can be automatically measured. A white sponge plate or styrofoam that has a composition structure similar to that of snow on the ground surface where it is projected.
Since the reference member consisting of a plate is placed, it is possible to measure in the same condition as when measuring the surface of snow when measuring the reference zero position where the snow height is zero when there is no snow. That is, the distance-measuring light projected from the light-transmitting means does not immediately reflect on the surface of the reference member, but once enters the inside of the reference member and repeatedly scatters. When a light is emitted in a state, a delay phenomenon occurs until the reflected light from the reference member enters the light detection means, and the presence of this delay phenomenon causes the reference zero position where the snow height is zero when there is no snow. It is possible to make the measurement conditions for the measurement of the snowfall and the measurement on the surface of the snow during the snowfall almost the same. Therefore, it is evaluated that the snow depth is less than the actual snow depth, Is zero It is possible to prevent the occurrence of such measurement results in advance, and it is possible to improve the measurement accuracy of the snow depth accordingly, and since a white type sponge plate or Styrofoam plate similar to snow is used as the reference member. ,
The reference member can be easily manufactured and easily installed, and the construction workability can be improved.

As described above, the intended purpose can be sufficiently achieved.

[Brief description of drawings]

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

FIG. 2 is a measurement explanatory diagram of the embodiment of the present invention.

FIG. 3 is a measurement explanatory diagram of the embodiment of the present invention.

FIG. 4 is a measurement chart of the embodiment of the present invention.

FIG. 5 is a sectional view of a reference member according to the embodiment of the present invention.

[Explanation of symbols]

L distance measuring light R reflected light K ground surface M surface to be measured Q reference member 1 Light transmitting means 7 Light detection means 12 Phase difference measuring means 14 Measuring means

Continuation of the front page (56) References JP-A-10-253772 (JP, A) JP-A-8-29547 (JP, A) JP-A-10-281854 (JP, A) JP-A-53-90967 (JP , A) JP 63-262582 (JP, A) JP 11-223675 (JP, A) JP 3326781 (JP, B2) JP 2732347 (JP, B2) JP 2794543 (JP, B2) JP B5 -37274 (JP, B2) JP-B-58-40710 (JP, B2) Jpn. 4-29430 (JP, Y2) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01W 1/00- 1/18 G01F 23/00-23/296 G01J 9/00-9/04 G01C 3/00-3/32 JISST file (JOIS)

Claims (2)

(57) [Claims] 1. A distance measuring light as a laser light modulated by a modulation frequency is projected from a light transmitting means onto a snow surface as a surface to be measured, and a part of the irregularly reflected light is received as a reflected light by a light detecting means. , When measuring the light wave phase difference between the distance measuring light and the reflected light to evaluate and measure the snow depth with respect to the ground surface, approximate the snow on the ground surface at the position where the distance measuring light is projected. Sponge board and Styrofoam of white type which have the following composition structure
An optical wave phase difference type automatic snow depth measuring method characterized by arranging a reference member using a rule plate . 2. A light transmitting means for projecting distance measuring light as laser light modulated at a modulation frequency onto a snow surface, and a light detecting means for receiving a part of irregularly reflected light from the snow surface as reflected light.
Phase difference measuring means for measuring the light wave phase difference between the distance measuring light and the reflected light, and measurement for calculating and evaluating the snow depth on the ground surface by the phase difference measuring signal output from the phase difference measuring means. A white color having a composition structure similar to that of snow, which is formed on the ground surface at the position where the distance measuring light is projected.
An optical wave phase-difference type automatic snow depth measuring device comprising a reference member made of a system sponge plate or styrofoam plate .