JPS6161354B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an ultrasonic snow texture detector that detects the quality of snow on a snow surface using ultrasonic waves.

Conventional technology It is generally known that the reflectance of ultrasonic waves changes depending on the quality of the snow, and the reflectance is high in compacted snow.
Reflectance is low in fresh snow. Conventionally, ultrasonic waves are emitted onto the snow surface, and the reflected and received signals are rectified and averaged to produce a detection signal that corresponds to the amplitude of the reflected and received signals.If the level of the detection signal is high, the snow quality on the snow surface is compacted or level. If the snow is low, it is treated as fresh snow.

Problems to be Solved by the Invention With such a conventional configuration, when attempting to correct the snow information obtained by the ultrasonic snow gauge using the obtained snow quality information, the overall configuration becomes complicated. be.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ultrasonic snow texture detector whose overall configuration can be simplified even when used for correcting snow cover information.

Means for Solving the Problems The ultrasonic snow texture detector of the present invention includes a transmitting system that emits tone burst-shaped ultrasonic waves from above to the snow surface, and a receiving system that receives reflected waves from the snow surface. a signal generating means for outputting a reference signal for the received signal of the reflected wave; and a signal generating means that compares the level of the received signal of the reflected wave with the level of the reference signal, and each time the level of the received signal exceeds the level of the reference signal. a comparator that outputs a signal to the output of the comparator, and instructs the signal generating means to change the level of the reference signal so that the counted value approaches a preset counted value by counting the number of pulse signals generated at the output of the comparator. The present invention is characterized in that it includes a control section and outputs the level of the reference signal as snow cover information corresponding to snow quality.

Effect With this configuration, since snow quality information is obtained by controlling the level of the reference signal applied to the comparator, when combined with an ultrasonic snow gauge, the first output from the comparator is adjusted from the ultrasonic reflection time. Simply configuring the structure to calculate the snow depth based on the time difference between the times when the reflected wave reception signal occurs is the same as correcting the measured snow depth and the reflectance of the snow surface, and the overall It can be easily configured.

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings. Figure 1 shows the configuration of an ultrasonic snow quality detector.
A control unit is configured to control each device described below and to determine snow quality based on information from the outside, and is composed of, for example, a microcomputer. Reference numeral 2 denotes a transmission system that emits ultrasonic tone burst waves according to instructions from the control unit 1, and is composed of an oscillator 2a, a tone burst generation circuit 2b, an amplifier 2c, and a transmission head 2d. teeth
The tone burst generating circuit 2b continuously outputs a sine wave of about 20 KHZ to 40 KHZ], and the tone burst generating circuit 2b is controlled by the control unit 1 to output an intermittent sine wave of the oscillator 2a [for example, 5 m
50 mS and then stop for 50 mS] to output a so-called tone burst wave. Further, a transmitting head 2d that emits into the air the tone burst wave output from the tone burst generating circuit 2b via the amplifier 2c is arranged at a predetermined height so as to be able to emit it from above toward the ground surface. 3 is a receiving system that receives reflected waves from the snow surface, and is composed of a receiving head 3a and an amplifier 3b.
The receiving head 3a is arranged at a predetermined height to convert the tone burst waves emitted from the transmitting head 2d, reflected by the snow surface, into electrical signals. A comparator 3c compares the level of the output signal of the receiving head 3a via the amplifier 3d with the level of the reference signal 3d, and outputs a pulse P each time the output level of the receiving head 3a exceeds the level of the reference signal 3d. do. Note that the reference signal 3d is provided by the control section 1 via the digital-to-analog converter 4.

The control section 1 includes a pulse number counting means 1e and a correction means 1.
The pulse number counting means 1e counts the pulses P of the output of the comparator 3c, and the correction means 1f counts the pulses P of the output of the comparator 3c, and the correction means 1f counts the pulses P when the counted value of the pulse number counting means 1e is not a preset number of pulses. The digital signal D generated by the digital signal generating means 1h is changed to change the level of the reference signal 3d output from the digital-to-analog converter 4, so that the counted value of the pulse number counting means 1e approaches the set number of pulses. It works like this. Further, the correction means 1f calculates the reflectance on the snow surface from the status of the currently instructed digital signal and the count value of the pulse number counting means 1e, and determines that if the reflectance is low, it is fresh snow, and if the reflectance is high, it is compacted snow. Then, use this as snow quality information and connect it to terminal 1.
Send to g.

Next, the operations of the control unit 1 and the comparator 3c will be described in detail based on FIG. 2 showing signal waveforms during compacted snow and FIG. 3 showing signal waveforms during fresh snow. Note that in both FIGS. 2 a and b and 3 a and b, a is the amplifier 3b.
b is the input signal to the comparator 3c, and b is the output signal of the comparator 3c.

When the tone burst generation circuit 2b of the transmission system 2 is instructed to generate, the tone burst generation circuit 2b transmits the oscillation signal from the oscillator 2a to the amplifier 2c for a predetermined period of time.
Send to. This oscillation signal is amplified by an amplifier 2c and emitted as an ultrasonic wave from a transmission head 2d toward the snow surface.

The reflected ultrasonic waves from the snow surface are received by the receiving head 3a of the receiving system 3 and amplified by the amplifier 3b.
The comparator 3c sends out a pulse P every time the reflected wave reception signal A amplified by the amplifier 3b exceeds the level B of the reference signal 3d of the digital-to-analog converter 4, as shown in FIG. This pulse P is counted by the pulse number counting means 1e and sent to the correction means 1f. The correction means 1f compares the number of pulses with a digital signal corresponding to the level of the reference signal 3d, calculates the reflectance of the reflected signal, and if the reflectance is large as shown in FIG. 2a, it is judged as piezoelectric, and the pulse number is third
If the number is less than the predetermined number of 5 as shown in Figure b, the correction means 1f determines that the reflectance is small and sends the snow quality information of the fresh snow to the terminal 1g, and sends the reference signal 3d to the digital signal generation means 1h. level from B′
Send a signal to lower it to B''.Reference signal 3d
If the pulse count is set to level B'' and the count value of the pulse number counting means 1e reaches the predetermined number of 5, the level B'' of the reference signal 3d will be adopted when detecting the next received signal. In this way, the snow quality information is transmitted, and the level of the reference signal for the reflected wave reception signal is further corrected according to the snow quality.

In the above embodiment, it has been explained that the control unit 1 performs only the operation of determining snow quality, but while adjusting the reception level via the digital-to-analog converter 4,
By determining the time difference between emitting the tone burst wave and receiving the reflected wave from the snow surface, we compensated for measurement errors due to changes in the reflectance of the snow surface using this time difference and constants such as the speed of sound and head height. Snow depth is required. In other words, in this case, as shown in FIG. 4, the snow depth determination means 1c and the transmission instruction means 1a are added to the control unit 1, so that the snow depth determination means 1c first receives the output signal from the comparator 3c. It is configured to detect the timing at which the wave is received.

FIG. 4 will be explained in detail. When transmission information arrives at the terminal 1b according to an operator's instruction, the transmission instruction means 1a instructs the tone burst generation circuit 2b to generate a tone burst wave, and informs the snow depth determination means 1c of the tone burst generation start time. Instruct.
The snow depth determination means 1c compares the tone burst generation start time of the transmission instruction means 1a and the arrival time of the pulse P of the comparator 3c, and determines the snow depth from the time difference and constants such as the speed of sound and the head height. It makes a judgment and sends snow depth information to terminal 1d.

In other words, if the level of the reference signal 3d of the comparator 3c is B regardless of the snow quality of the snow surface, the snow quality is not compact snow as shown in Fig. 2, but fresh snow with low reflectance as shown in Fig. 3. In this case, the timing T ₁ when the received signal A′ first crosses level B is delayed compared to the timing T ₂ when the snow is packed with high reflectivity.
A time delay in detecting the received signal due to this difference in reflectance appears as an error in the snow depth in the measurement result. However, if the reference signal 3d applied to the comparator 3c is changed according to the snow quality as shown in FIG. 4, even if the snow surface is fresh snow, the reflected wave received signal A' Level B'' of 3d can be processed by determining the first crossing timing T ₃ (T ₃ ≒ T ₂ ) as the reflected wave reception time, and since there is no delay like timing T ₁ , the reflection on the snow surface Accurate snow depth can be calculated regardless of the rate.

Effects of the Invention As explained above, the ultrasonic snow texture detector of the present invention includes: a transmitting system that emits tone burst-shaped ultrasonic waves from above to the snow surface; a receiving system that receives reflected waves from the snow surface; a signal generating means for outputting a reference signal for the received signal of the reflected wave; and a signal generating means that compares the level of the received signal of the reflected wave with the level of the reference signal, and each time the level of the received signal exceeds the level of the reference signal. a comparator that outputs a signal to the output of the comparator, and instructs the signal generating means to change the level of the reference signal so that the counted value approaches a preset counted value by counting the number of pulse signals generated at the output of the comparator. Since the control unit outputs the level of the reference signal as snow quality information corresponding to the snow quality, it is possible to know the snow quality of the snow surface using ultrasonic waves.

In addition, since the level of the reference signal applied to the comparator follows the level of the received signal, the tone burst-shaped ultrasonic wave is emitted onto the snow surface, and from the time of emission until the reflected wave is received. When combined with an ultrasonic snow gauge configured to calculate the snow depth based on the required time, the speed of sound, and the mounting height of the transmitting/receiving head, the output signal of the comparator is generated first. By using the time when the reflected wave is received in the ultrasonic snow gauge, the comparator part can be used both for snow texture detection and snow depth measurement. If both are used in common, the configuration will not only be simpler, but it will also be possible to compensate for measurement errors in snow depth due to changes in snow quality without the need for a special correction circuit, allowing for accurate snow depth. This can contribute to the measurement of

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the ultrasonic snow texture detector of the present invention, Fig. 2 is an explanatory diagram of the operation of the same embodiment during compacted snow, and Fig. 3 is an explanatory diagram of the operation of the same embodiment during fresh snow. , FIG. 4 is a block diagram of another embodiment. 1...Control unit, 1e...Pulse number counting means, 1
f... Correction means, 1h... Digital signal generation means, 2... Transmission system, 2a... Oscillator, 2b... Tone burst generation circuit, 2c... Amplifier, 2d...
...Transmission head, 3...Reception system, 3a...Reception head, 3b...Amplifier, 3c...Comparator, 3d...
Reference signal, 4...Digital-to-analog converter.

Claims (1)

[Claims] 1. A transmitting system that emits tone burst-shaped ultrasonic waves from above to the snow surface, a receiving system that receives reflected waves from the snow surface, and a signal generating means that outputs a reference signal for a received signal of the reflected waves. a comparator that compares the level of the received signal of the reflected wave with the level of the reference signal and outputs a signal every time the level of the received signal exceeds the level of the reference signal; and a pulse generated at the output of this comparator. and a control section that counts the number of signals and instructs the signal generating means to change the level of the reference signal so that the counted value approaches a preset counted value, and adjusts the level of the reference signal to a level corresponding to the snow quality. Ultrasonic snow texture detector that outputs information.