JPS63210733A - Method and device for measuring depth of snow coverage - Google Patents

Abstract

PURPOSE:To measure the depth of snow coverage with high accuracy by projecting a light wave on the surface of the snow coverage from a light wave transmitter, receiving its reflected light by a light wave receiver, and measuring the phase difference between its light reception signal and a light reception signal received directly from the light wave transmitter. CONSTITUTION:The light wave of specific modulation frequency is projected on the surface of the snow coverage from the light wave transmitter provided to a measurement part 7 at the height H1 of a column 3 stood on the ground surface GL and its reflected light from the snow surface is received as the reception signal by the light wave receiver. At the same time, the light wave from the transmitter is received as the reception signal directly by the receiver. Then a mixer provided to the receiver measures the phase difference between both reception signals and a measurement arithmetic processing part 11 processes the phase difference to find the distance (d) between the receiver and snow surface. Then H=H1-dcostheta (theta: the tilt angle of the receiver to the vertical) is solved to find the depth H of the snow coverage. Further, this measurement is performed continuously plural times and the depth of the snow coverage is measured by using the mean value, so reliable data is obtained.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention projects a light wave from a light wave transmitter toward a snow surface, and receives reflected light from the snow surface with a light wave receiver. The present invention relates to a method and apparatus for measuring snow depth based on a phase difference between a first received signal and a second received signal obtained by directly receiving a light wave from a light wave transmitter by a light wave receiver.

(Prior Art) Ultrasonic snow gauges and infrared snow gauges are conventionally known as means for measuring the depth of snow.

In other words, an ultrasonic snow gauge uses an ultrasonic transducer installed above the snow surface to emit ultrasonic waves toward the snow surface, and the ultrasonic waves reflected from the snow surface cause the snow to be connected to the ultrasonic transducer. The processing device measures the time and sends an external output. Note that the propagation speed of ultrasonic waves changes depending on the temperature, so some correction is performed using a thermometer.

In addition, an infrared snow gauge emits light toward the snow surface from an infrared light emitting diode as a light emitter mounted above the snow surface, and receives reflected light from the snow surface with a light receiving element mounted above the snow surface. It is processed and output by a processing device connected to the infrared light emitting diode and the light receiving element. In this method, as the height of the stack changes, the light receiving element is moved by a drive motor to receive light.

(Problem to be Solved by the Invention) However, among the conventional techniques described above, in the former ultrasonic snow gauge, sound speed errors occur due to air temperature, wind, temperature, etc. of ultrasonic waves, so sound speed correction must be performed. First, there are problems with the accuracy and reliability of the measured depth.

On the other hand, in the latter type of infrared snow gauge, the light receiving element must be moved, and the movement affects the accuracy of snow depth. That is, similar to the ultrasonic snow gauge, there is a problem in the accuracy and reliability of the measured depth due to errors occurring in the mechanical converter when the light receiving element is moved.

The purpose of the present invention is to improve the above-mentioned problems by providing reliable and highly accurate snow depth measurement results that are not affected by temperature, wind speed, humidity, etc., and which can be used stably over a long period of time. The object of the present invention is to provide a method and device for measuring snow depth.

[Structure of the Invention (Means for Solving Problems)] In order to achieve the above object, the first invention provides a light wave transmitter/receiver of a light wave transmitter/receiver provided at the upper part of a support that is erected on the ground. A first light reception signal is obtained by projecting a light wave modulated to a predetermined frequency toward a snowy surface, and receiving reflected light from the snowy surface by a lightwave receiver of a lightwave transmitter/receiver, and from the lightwave transmitter to a lightwave receiver. The second beam was irradiated towards the target and received by the light wave receiver.
A method for measuring snow depth was constructed by measuring the phase difference between the measured phase difference and the received light signal, and calculating the measured phase difference into the snow depth in a measurement calculation processing section connected to the light wave receiver.

In addition, the second invention provides a mounting flange on the upper part of a support that is erected on the ground, and a light wave transmitter that projects light waves onto the snow surface via a support bracket on the mounting flange, and a light wave transmitter that projects light waves from the snow surface. A light wave transmitter/receiver is rotatably provided with a light wave receiver that receives the light wave at approximately the same height position and close to the light wave receiver, a phase locker is provided on the light wave transmitter, a mixer is provided on the light wave receiver, and the light wave receiver is provided with a light wave receiver. A measurement calculation processing unit was connected to the device to construct a snow depth measuring device.

(Operation) By employing the present invention, a light wave modulated at a predetermined frequency is projected toward the snow surface from a light wave transmitter of a light wave transmitter/receiver installed in a branch installed on the ground. The light reflected from the snow surface by the projected light wave is received by the light wave receiver of the light wave transceiver as a first reception signal, and the light wave from the light wave transmitter is directly received by the light wave receiver as a second reception signal. The phase difference between the first received signal and the second received signal is measured by a mixer installed in the light wave receiver, and the phase difference is processed by the measurement processing unit and outputted as a voltage, for example, and automatically output. Snow depth can be obtained.

Moreover, the obtained snow depth is a more accurate and reliable measurement value than with conventional methods.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

Referring to FIG. 1, the snow depth measuring device 1 is located at the ground level GL.
A pillar 3 erected above, a measuring part 7 attached to the upper part of the pillar 3 through a support frame 5 toward the lower layer, and a measuring part 7 connected to the measuring part 7 by an external output connector 9. When the snow falls to a certain height above the ground GL, the device, which is composed of a control device 11 that performs measurement calculation processing, etc., transmits light waves from a light wave transmitter of a light wave transmitter/receiver, the details of which will be described later, provided in the measuring section 7. The first received signal is projected toward the snow surface and the reflected light from the snow surface is received by the light wave receiver of the light wave transmitter/receiver, and the second reception signal is received by the light wave receiver directly from the light wave transmitter. The actual snow depth is obtained by measuring the phase difference with the signal and determining the distance d between the light wave transmitter/receiver and the snow surface.

The external configuration of the measuring section 5 is shown in FIGS. 2, 3, and 4. In FIGS. 2, 3, and 4, a flange 13 is attached to the support frame 5 so as to extend in the left-right direction in the direction orthogonal to FIG. As can be seen from the drawings and FIG. 4, a plurality of brackets 15 are integrally supported at a distance. Between the brackets 15, the protrusion at the bottom of the L-shaped bracket 17 is installed, and the bottle 19 is inserted into the bracket 15 and the protrusion of the bracket 17, and the nut 21 is inserted from both sides of the bracket 15. For tightening and mounting, the bracket 17 is rotatably supported by the bracket 15.

The above-mentioned mounting is for the other end of the bracket 13.A plurality of brackets 23 are isolated and integrally supported at the right end in FIG. 2, and a bar 25 having a threaded portion is installed between the brackets 23. Insert the bottle 27 into the bracket 23 and the bar 25, and insert the foot 29 from both sides of the bracket 23.
When tightening, the bar 25 is fixed to the bracket 23.

The threaded portion of the bar 25 is inserted into the other end of the lower part of the mounting bracket 17, and removed from the top and bottom of the bracket 17 through the screws 1-31, as shown in FIGS. 2 and 4. The mounting supports the bracket 17.

With the above configuration, by adjusting the nut 31 up and down, the mounting bracket 17 is rotated about the bin 21 as a fulcrum.

The light wave transmitter/receiver 3 is mounted on the upper part of the bracket 17.
A light wave transmitter 35 and a light wave receiver 37 are provided as shown in FIG. Light receiving lens 4
1 is shown.

A hollow cylindrical snow protection hood 43 is attached to the front left side of the bracket 17 in FIG. I am accomplishing it. On the other hand, the mounting is on the rear side of the bracket 17 on the right side in FIG.
A hollow cylindrical protective cover 45 with a hemispherical rear end is attached, and serves to protect the light wave transmitter/receiver 33 from snow or wind.

One end of the external output connector 9 is connected to the light wave transmitter/receiver 33 through a hole drilled in a part of the bracket 17, and the other end is connected to the control device 11 as described above.

By adjusting the nut 31, the light wave transmitter/receiver 33 can be mounted on the bracket 17 using the bin 19 as a fulcrum.
The tilt angle θ with respect to the snow surface as shown in FIG. 1 can be set in advance while measuring the snow depth.

A control device 11 that performs measurement calculation processing and the like with the measurement section 7
A block diagram of the configuration is shown in FIG. In FIG. 5, the light wave transceiver 33 in the measuring section 7 is composed of a light wave transmitter 35 and a light wave receiver 37. light wave method,
The transmitter 35 includes an optical system section 47 and a light wave transmitter section 49,
The optical system section 47 is composed of a projecting lens 39 as an objective lens, a reflecting mirror 51 with a hole in the center, a shutter plate 53 that squeezes light waves, and an automatic light amount adjustment device 55 that automatically adjusts the amount of light waves. has been done.

The shutter plate 53 and the automatic light amount adjustment device δ55 are controlled by the shutter motor 5 under control from the control device 11, which will be described later.
7. This is done by driving the automatic light ω adjustment motor 59.

The light wave transmitter 49 includes a 15MHz oscillator 61. It is composed of a calculation frequency dividing circuit 631, a light emitting element excitation circuit 652, a phase locking circuit 67, a filter signal processing circuit 69, and a light emitting element 71.

On the other hand, the light wave receiver 37 includes an optical system section 73 and a light wave receiving section 75.
The optical system section 73 is composed of an objective light receiving lens 41 and a reflecting mirror 77 having a hole in the center. The light wave receiving section 75 includes a light receiving element 77, a high frequency amplifier 79. It consists of a mixer (analog multiplier) 81 and a temperature compensation circuit 83.

15MH of the light wave transmitter 49 in this light wave transmitter 35
The light wave oscillated by the z oscillator 61 is converted into a modulation frequency by a counting frequency divider circuit 63, and the modulation frequency is intensely modulated by a light emitting element excitation circuit 65.

A light transmission signal of modulated light whose intensity is modulated is projected from the light emitting element 75 to the reflection mirror 71, reflected by the reflection mirror 71, and sent to the projection lens 39. The light transmission signal sent to the light projection lens 39 is condensed and projected onto the snow covered surface as shown in FIG.

The reflected light reflected from the snow surface is collected by the light receiving lens 41, further reflected by the reflecting mirror 75, and received by the light receiving element 77 of the light wave receiving section 75 as a first received signal. Further, the light transmission signal from the light emitting cable 71 is transmitted to the reflection mirror 51.7.
5 and is received by the light receiving element 77 as a second received signal, and is received by the light receiving element 77 with a phase difference between it and the first received signal from the snow surface.

Now, after emitting the light transmission signal from the light emitting element 71,
If the time taken to obtain a received signal at the light receiving element 77 is defined as T=2d/c (sea), where d: the light emitting element 71. Distance (IB) from light receiving element 77 to snowfall C: Speed of light (13×108 m/sec).

Therefore, by measuring the time T, d = Tx
The distance d can be determined as c/2. However, in reality, since the speed of light C is very high, the time T becomes very small, making it difficult to perform high-resolution measurement. The phase is delayed relative to the received signal of No. 2 in proportion to the distance.

Since the modulation frequency of the light transmission signal is 15 MH2, the wavelength λ=C/15 MHz: 20 m.

Here, the distance d, the phase of the reflecting surface in the snowfall, and the phase of the light receiving position have a relationship as shown in FIG.

For example, the light emitting element 71. If the distance d from the light-receiving element 77 to the reflective surface, which is a snow-covered surface, is 51, and the phase of the light transmission position is Oo, then the phase of the reflective surface is λ/4. Again, the phase on the surface of the light receiving element 77 is λ/2, so there is a relationship between the distance d and the phase difference φ: d=λ/2X(φ/2π), where φniradian. Distance can be determined by measuring the phase difference in position.

When d>λ/2, that is, when d is greater than or equal to 10a+, the phase returns to O again, resulting in a sawtooth shape as shown in FIG.

That is, d-λ/2xn+λ/2x(φ/2π), where n =0.1.2. ... This shows that there is a proportional relationship between the distance lll1id and the phase difference φ, and by measuring the phase difference φ, the distance d can be found, but in this example, this is done in the case of n=Q. .

15 M of the received signal with a phase difference received by the light receiving element 77
The Hz signal is amplified by a high frequency amplifier 79 and input to a mixer 81 . Note that in order to compensate for constant changes in the temperature of the light receiving element 77, the temperature of the light receiving element 77 is compensated by a temperature compensation circuit 83.

On the other hand, 15MHz inputted from the 15MHz generator 61 to the phase locking circuit 67 or via the counting divider circuit 63 is input to the phase locking circuit 67 at a constant frequency (for example <15M-15K). Hz, and that constant frequency is converted into a local oscillation signal (15M-15K) by removing unnecessary components and noise in a filter signal processing circuit 69.
The signal is taken into the mixer 81 as Hz.

The mixer 81 performs frequency conversion to temporally expand the phase difference. In the mixer 81, for example, when input signals are 5iO1α and sinβ, the output is sin a −sin β=1/2− (cos
(α−β)−COS (α1β)), α−
Two frequencies are outputted with β as a difference component and α+β as a sum component, and the principle is to extract the difference component among these frequencies. Therefore, the mixer 81 has sin(1
5M)-12> and sin (15M-15K) H
Since z is input, the intermediate frequency 15 is the difference component.
KHz can be extracted as output. Phase 2 of this 15KH2
When converting π (360°) into time, Tc = 1/15
KHz-66, 6xlO'seC.

In addition, the phase of 15MHz of the received signal is 2π (360°).
Since x 10-9 sec, Tc = 1000x
With TA, the same phase difference is magnified 1000 times temporally, making it easier to measure the phase difference and improving resolution.

A received signal amplifier 85 is connected to the light wave receiving section 75 . That is, the intermediate frequency amplifier 8 of the received signal amplifier 85
7 is connected to the mixer 81 of the light wave receiving section 75, and the intermediate frequency 15Kl-1z from the mixer 81 is amplified by the intermediate frequency amplifier 87. An automatic gain controller 89 is connected to the intermediate frequency amplifier 87, and this automatic gain controller 89 automatically controls the frequency, and a bandpass circuit 91 connected to the automatic gain controller 89 controls the frequency. Controls the amplification rate. The intermediate frequency that has passed through the bandpass circuit 91 is subjected to waveform processing by a waveform shaper 93 connected to the bandpass circuit 91.

Note that an automatic gain detector 97 is connected between the bandpass circuit 91 and the waveform shaper 93 via a rectifier circuit 95, and the automatic gain detector 97 is connected to the automatic gain controller 89. and feedback control of the intermediate frequency.

A light amount comparison circuit 99 connected to the rectifier circuit 95 and the automatic gain detector 97 is connected to the automatic light m adjustment motor 59 via an input/output converter to be described later, and compares the light values. .

Further, a control circuit 103 for controlling the shutter motor 57 is connected to a rectifier circuit 101 connected between the intermediate frequency amplifier 87 and the automatic gain controller 89. This control circuit 103 is connected to a shutter motor 57 via an input/output conversion device, and controls the shutter plate 53 to be squeezed.

A phase detector 105 is connected to the waveform shaper 93, and the intermediate frequency waveform processed by the waveform shaper 93 is taken into the phase detector 105, converted from analog to digital, and the phase difference is calculated. φ is being detected.

A counting logic circuit 107 is connected to the phase detector 105, and in this calculation logic circuit 107, the phase detector 1
Based on the phase difference φ obtained in 05, d−λ/2X(
φ/2π) gives the distance d.

The counting logic circuit 107 has computer units 1 to 10.
9 is connected, and computer unit 1
09 is connected to a ROM 111. This ROMI
11 stores in advance the height Hl from the ground GL to the lightwave transceiver 33 and the inclination angle θ of the lightwave transceiver 33 with respect to the vertical.

The computer unit 109 includes a counting logic circuit 10
The distance d obtained in step 7, the height H+ and the inclination angle θ stored in the ROM 111 are imported, and the
The calculation process is performed using the formula 1-d 008θ.

The computer unit 109 has an input/output converter 113
are connected to the input/output converter 113, and a digital/analog converter 115.degree. digital liquid crystal display 117. BUSY, equipment abnormality.

An error display signal 119 such as a distance measurement error, each motor, etc. are connected.

Note that a power supply (DC/DC converter) 121 is connected from the AC power supply via a DC power supply of +12V, and is connected to various devices.

The voltage of the snow depth H converted by the digital/analog converter 115 is output as data output based on several measurements, as shown in FIG. 8, for example. Therefore, a more accurate snow depth H is required.

Further, digital values can also be displayed and read on the digital liquid crystal display 117.

Next, the operation of this embodiment will be briefly described. First, when the power supplied from the outside is turned on, measurement is automatically started during a warm-up period of a certain period of time. During the warm-up period, the main unit outputs a BUsY signal as an error display signal 119, and even if there is a data output request, it is ignored. During the warm-up period, the computer unit 109 of the main body checks the amount of received light and the internal calibration optical path to confirm whether the device is operating normally.

When the amount of received light becomes appropriate, measurement starts automatically. The measurement takes at least 2 seconds, for example, and the measurement is continued until the power is turned off.

As shown in FIG. 8, moving averaged values are continuously outputted as data output. In other words, the average value of the first data and the second data is output, and the average value and the third
The average value of the data for the 0th measurement is output, and for the 0th measurement, the average value for up to the nth measurement is output. Note that the data in this embodiment is output in units of aha.

During continuous measurement, between each measurement, the light m comparison circuit 99 drives the automatic light amount adjustment motor 59 to automatically adjust the light amount! ! ! The device 55 automatically adjusts the amount of light.

As can be seen from the above explanation, snow depth can be measured automatically and accurately. The light wave transmitter/receiver is protected by a snow hood and protective cover, so it can perform measurements under all snow conditions and strong winds.

The light wave transmitter/receiver is installed above the snow and measures instantaneously, so it does not directly affect the snow surface.

Since the snow surface has an uneven shape, extremely reliable data can be obtained by averaging several consecutive measurements. If the slope of the snow surface is within 45 degrees, sufficient measurement is possible.

Furthermore, since the mechanism of this measuring device is simplified, failures are extremely rare and it is advantageous in terms of maintenance.

Note that the present invention is not limited to the above-mentioned embodiments,
By making appropriate changes, other embodiments can be implemented.

[Effects of the Invention] As can be understood from the description of the embodiments above, according to the present invention, it is possible to achieve high precision and accuracy compared to the conventional acoustic wave method using temperature correction or the light wave method using a lens. Snow depth can be measured automatically.

Since the snow surface is uneven, the snow depth is measured several times in succession and the average value is used to measure the snow depth, making it possible to obtain extremely reliable data.

The light wave transmitter/receiver is protected by a snow hood and protective cover, so measurements can be taken in all snow conditions and even under strong winds.

Since the configuration of this device is simple, failures are extremely rare and it is very advantageous in terms of maintenance.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the entirety of the present invention. FIG. 2 is an enlarged side view of the section viewed from the arrow ■ in FIG. 1, FIG. 3 is a front view of FIG. 2, and FIG. 4 is a rear view of FIG. 2. FIG. 5 is a block diagram showing the main parts of this embodiment. FIG. 6 is a diagram showing the relationship between the distance d between the light wave transceiver and the snow surface, the phase of the reflecting surface, and the phase of the light receiving position. FIG. 7 is a diagram showing the relationship between the distance @d and the phase φ, and FIG. 8 is an example of data showing the snow depth. [Explanation of symbols representing main parts of the drawing] 1...Snow depth measuring device 3...Strut 33...Light wave transmitter/receiver 35...Light wave transmitter 37...Light wave receiver 43.
...Snow protection hood 45...Protective cover 71...Light emitting element 77...Light receiving element 81...Mixer 105.
...Phase detector 109...Computer unit representative Patent attorney Yasuo Miyoshi 2.5m5m7.5m Figure 6 Figure 7 Figure 8

Claims (4)

[Claims] (1) Light waves modulated at a predetermined frequency are projected toward the snow surface from the light wave transmitter/receiver installed at the upper part of the pillar installed on the ground, and the light reflected from the snow surface is converted into light waves. Measuring the phase difference between a first received light signal received by a light wave receiver of a transceiver and a second received light signal irradiated from the light wave transmitter toward the light wave receiver and received by the light wave receiver, A method for measuring snow depth, characterized in that the measured phase difference is calculated into a snow depth by a measurement calculation processing unit connected to the light wave receiver. (2) The snow depth measuring method according to claim 1, wherein the measurement calculation processing section averages a plurality of snow depths and outputs the average as a voltage value. (3) A mounting flange is provided on the upper part of the pillar installed on the ground, and a light wave transmitter that projects light waves onto the snow surface via a support bracket on the mounting flange and a light wave receiver that receives reflected light from the snow surface A light wave transmitter/receiver is rotatably provided with a light wave transmitter and receiver in close proximity to each other at approximately the same height position, a phase fixer is provided on the light wave transmitter, a mixer is provided on the light wave receiver, and a measurement calculation process is performed on the light wave receiver. A snow depth measuring device characterized by connecting parts. (4) The snow depth measuring device according to claim 3, wherein the light wave transmitter/receiver is covered with a snow protection hood on the front side and a protective cover on the rear side.