JPH0627874B2 - Snow cover - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is used for measuring the depth of snow.

The present invention relates to a snow gauge capable of reducing the measurement error of the snow depth near the ground surface.

[0003]

2. Description of the Related Art Conventionally, a snow cover using this kind of ultrasonic ring transducer has an ultrasonic pulse generated by a respiratory vibration of the transducer from a space separated from a measurement surface, as shown in the measurement principle in FIG. Was transmitted, and the propagation time when the reflected wave on the measurement surface was received was converted to the distance and used as the measurement value (snow depth value).

That is, since the speed at which ultrasonic waves propagate in the air is approximately 340 m / sec, which is almost constant, the propagation distance can be determined by knowing the propagation time of the sound waves. The ultrasonic pulse emitted from the ultrasonic transmitter / receiver 21 is reflected by the snow surface 22 and is received again by the ultrasonic transmitter / receiver 21. The round-trip propagation time t (sec) of this ultrasonic pulse is D (m), the distance from the ultrasonic transmitter / receiver 21 to the ground surface 23, and H, the height of snow.
(M), the speed of sound in air is C (m / sec),

[0005]

[Formula 1] t = 2 (D−H) / C.

When the propagation velocity t (sec) is measured, the distance (D− from the ultrasonic transmitter / receiver 21 to the snow surface 22 is calculated using the equation (1).
H) can be obtained. The speed of sound C is a function of temperature and changes by about 0.2% per degree Celsius. The change in the speed of sound due to this temperature is T (° C), which is the temperature measured by the thermometer sensing unit 24, C ₀ is the speed of sound (331.45m / sec) at 0 ° C, and the temperature coefficient of sound speed (0.607m / sec) is Let α be

[0007]

Equation 2 can be corrected by C = C ₀ + αT.

[0008]

In the conventional snow meter based on the above-mentioned operation principle, since the density is low at the beginning of snowfall, the ultrasonic waves penetrate a large amount from the snow surface to the inside. Is disturbed, and there is a problem that the propagation time cannot be accurately detected. In particular, the tendency is remarkable in the case of snow that starts to fall near the ground surface and snow that has finished falling.

FIGS. 10 (a), 10 (b) and 10 (c) show the state of receiving waves. In the case of FIG. 10 (a), the waveform of the receiving wave when there is no snow, and in FIG. Waveform of received wave when piled up,
(c) is the waveform of the received wave at the beginning of snowfall. In this way, at the beginning of snowfall, the rate of ultrasonic waves permeating is large, so the reflection position is not fixed and the waveform is disturbed.

The present invention solves such a problem, and an object of the present invention is to provide a snow meter capable of obtaining an accurate measurement value by eliminating a measurement error of the snow depth near the ground surface.

[0011]

DISCLOSURE OF THE INVENTION The present invention is directed to a panzamast erected on the ground surface, an ultrasonic transmitter / receiver mounted near the tip of the panzamast, and a pulse from the ultrasonic transmitter / receiver toward the ground surface. In the snow gauge equipped with a calculation control means for transmitting a signal, receiving a pulse signal reflected on the snow surface, and calculating the snow depth from the elapsed time, a small snow depth is provided inside or near the pan-zamast. A light reflection type snow cover is installed to detect the value, and when the measurement result of this light reflection type snow cover is within the range, the measurement result of this light reflection type snow cover is selected, and the measurement result is It is characterized in that it is provided with a selecting means for selecting an output value of the arithmetic control means when the value exceeds the range.

The range of the light reflection type snow cover is preferably 10 cm or less.

[0013]

[Operation] An ultrasonic wave transmitter / receiver mounted near the tip of a pan-zamast standing on the ground surface, and a pulse signal transmitted from the ultrasonic wave transmitter / receiver toward the ground surface and received by the snow surface A snow cover equipped with a calculation control unit that calculates the depth of snow from the elapsed time, and a light reflection type snow cover installed inside or near the Panzamast to detect small snow depths When the measurement result of the snow cover is within a predetermined range (for example, 10 cm or less), the measurement result of the light reflection type snow cover is selected as the depth of snow, and the measurement result exceeds the specified range. Occasionally, the output value of the arithmetic control means is selected as the snow depth.

As described above, snowfall near the ground surface is measured by a light reflection type snow gauge, and snowfall over a range of a predetermined depth or more is measured by an ultrasonic snow gauge.
It is possible to accurately obtain the value of snow depth in all measurement ranges.

[0015]

Embodiments of the present invention will now be described with reference to the drawings. 1 and 2 are diagrams showing the configuration of an embodiment of the present invention.

In the embodiment of the present invention, the pan-zamast 1 is erected on the ground surface 23, the ultrasonic transmitter / receiver 21 is mounted near the tip of the pan-zamast 1, and the ultrasonic transmitter / receiver 21 is directed toward the ground surface 23. 1 to transmit a pulse signal, receive a pulse signal reflected on the snow surface 22, and calculate the snow depth from the elapsed time, and as a feature of the present invention, FIG. As shown in the figure, or inside the pan-the-mast 1, or near it, as shown in Fig. 2, a light reflection type snow gauge 3 for detecting small values of snow depth is installed. When the measurement result is within the range, the measurement result of the light reflection type snow gauge 3 is selected, and when the measurement result exceeds the range, there is provided a selection means (not shown) for selecting the output value of the arithmetic control means. The range of the light-reflecting snow cover 3 is set to 10 cm or less.

FIG. 3 is an enlarged view of portion A of FIG. The light-reflecting snow cover 3 provided in the present embodiment has the same structure and principle as the light-reflecting snow cover shown in FIG. 4, and is short so as to detect a range up to about 10 cm above the ground surface 23. It is composed. The detection pitch a is set at an interval suitable for the measurement accuracy.

The structure of the light reflection type snow gauge will now be described with reference to FIG. The light reflection type snow meter is a detection pole 31 standing on the ground surface 23 and the ground surface of this detection pole 31.
A sensor 33, which is arranged at a large number of detection points T _{1 to} T _n corresponding to the distance from 23 and which sends out the presence or absence of snow at the detection points T _{1 to} T _n as an output signal, and the output signal of this sensor 33 And circuit means 32 constituted by a printed circuit board for outputting the depth.

FIG. 5 is a block diagram showing the configuration of the circuit means 32. The circuit means 32 is a sensor output capturing means for capturing the output signal of the sensor 33 over the entire measurement range at the measurement time.
32a, a storage means 32b for storing, as data, the output signal of the sensor 33 over the entire measurement range captured by the sensor output capturing means 32a, and the data captured newly and the data at a measurement time slightly before. And a comparison processing unit 32c that automatically excludes an irrational change among the changes of each sensor 33.

Further, the sensor 33 has a structure shown in FIG.
As shown in cross section, it includes a light emitting element 33a arranged with a separator 31a interposed, and a light receiving element 33b receiving the output light of the light emitting element 33a.

In the embodiment of the present invention, the light reflection type snow meter thus constructed is arranged as shown in FIG. 3 for measuring the depth of snow covering a small range on the ground surface 23.

Next, the operation of the embodiment of the present invention thus constructed will be described.

As shown in FIG. 7, if it is assumed that there is 3 cm of snow, the ultrasonic waves emitted from the ultrasonic transmitter / receiver 21 will penetrate into the snow layer, resulting in an ideal as shown in FIG. The propagation time t ₀ when reflected in a typical reception state does not become, and the disturbance as shown in the figure causes a delay of t ₁ and the actually measured propagation time becomes t ₂ . Therefore, although the actual depth of snow is 3 cm, it is measured as 1 cm, for example, and a measurement error of 2 cm occurs.

In order to eliminate such an error in measuring the depth of snow near the ground surface, as shown in the flow of operation in FIG. 8, first, an ultrasonic wave transmitter / receiver 21 transmits a pulse signal by an ultrasonic wave and propagates it. In addition to measuring the time, light is also sent from the light-reflecting snow cover meter 3 that is also installed to measure the depth of snow. Then, the depth of snow is calculated based on the data obtained by this measurement, and it is judged whether or not the measurement result by the light reflection type snow gauge 3 is within a predetermined range. The value of the depth of snow covered by the sound wave is a value measured near the ground surface 23, and the measurement result by the light reflection type snow gauge 3 is selected.

If the result of measurement by the light reflection type snow meter 3 exceeds a predetermined range, it is determined that the value of the depth of snow accumulated by ultrasonic waves does not mean that the vicinity of the ground surface 23 is measured. The measured value using is selected as the snow depth value.

As described above, in the case of snowfall in the range of 10 cm or less from the ground surface 23, the value measured by the light reflection type snow gauge 3 is taken as the depth of the snowfall, and in the case of snowfall in the range of more than 10 cm, it is measured by ultrasonic waves. By setting the measured value to the depth of snow, it becomes possible to accurately measure the depth of snow over the entire range.

[0027]

As described above, according to the present invention, the ultrasonic snow gauge and the light reflection type snow gauge are provided side by side, and the measurement by the ultrasonic snow gauge is likely to cause an error in the measurement near the ground surface. If the range is set, and the value is less than that range, the value measured by the light-reflecting snow cover is taken as the depth of snow, and if it is more than that range, the value measured by the ultrasonic snow cover is taken as the depth of snow. The effect is that accurate snow depth values can be obtained over a range.

[Brief description of drawings]

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

FIG. 2 is a diagram showing another example of the configuration of the embodiment of the present invention.

FIG. 3 is an enlarged view of part A shown in FIG.

FIG. 4 is a diagram showing a configuration of a light reflection type snow cover according to an embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of circuit means of the light reflection type snow meter.

6 is a sectional view taken along the line AA ′ of the sensor unit shown in FIG.

FIG. 7 is a diagram for explaining the state of wave transmission and wave reception of the ultrasonic snow cover according to the embodiment of the present invention.

FIG. 8 is a flow chart showing the flow of operation of the embodiment of the present invention.

FIG. 9 is a diagram illustrating the configuration and measurement of a conventional example ultrasonic snow cover.

10 (a), (b), and (c) are diagrams showing a state of transmission and reception of a conventional ultrasonic snow cover.

[Explanation of symbols]

 1 Panzamast 3 Light-reflecting snow cover 21 Ultrasonic transmitter / receiver 22 Snow cover 23 Ground surface 24 Thermometer sensing part 31 Detection pole 31a Separator 32 Circuit means (printed circuit board) 32a Sensor output acquisition means 32b Storage means 32c Comparison processing means 33 Sensor 33a Light emitting element 33b Light receiving element

Claims (2)

[Claims] 1. A pan-zamast which is erected on the ground surface, an ultrasonic transmitter-receiver attached near the tip of the pan-zamast, and a pulse signal which is transmitted from the ultrasonic transmitter-receiver to the ground surface so that the snow surface Receives the reflected pulse signal,
In a snow cover equipped with a calculation control means for calculating the snow depth from the elapsed time, inside or in the vicinity of the panzamast, a light reflection type snow cover for detecting a small value of the snow depth is provided side by side. When the measurement result of the reflection type snow meter is within the range, the measurement result of the light reflection type snow meter is selected, and when the measurement result exceeds the range, the output value of the arithmetic control means is selected. A snow cover characterized by having a selection means. 2. The snow cover according to claim 1, wherein the range of the light reflection type snow cover is 10 cm or less.