JPS592550Y2 - snow gauge - Google Patents

Description

[Detailed Description of the Invention] The purpose of the present invention is to improve the measurement accuracy of a snow gauge for automatically measuring snow depth at remote locations.

Generally, snow depth can be measured by emitting ultrasonic waves toward the ground from a certain height and measuring the time interval from transmission to delivery.

As a conventional measurement method of this type, a signal sequence shown in FIG. 1 is known.

In the figure, A is the transmission timing signal of the ultrasonic tone burst wave, A is the gate signal that determines the reception timing, C is the transfer rectification signal, and a in the figure is generated when the voltage is greater than the threshold voltage compared to the transfer. The receiving pulse, E, is a gate signal that is the measurement time from transmitting to receiving, and is created by the rising edge of the transmitting timing signal and the rising edge signal of the transfer pulse.

That is, the measurement method shown in FIG. 1 is a method in which the time from ultrasonic wave transmission to reception is measured and read directly as snow depth data.

However, when a measuring instrument using such a sound wave is actually operated outdoors in the presence of snow, there is a significant change in the delivery amplitude depending on the type of snow (in experiments, there is a change of 30 to 40 dB).

), and wind noise increases, making accurate measurements impossible.

For example, in the case of a snowstorm, the reception wave amplitude may decrease, resulting in no delivery, or wind noise may cause a malfunction in which the reception pulse rises before reception.

FIG. 2 shows an example of such a case.

In FIG. 2, il 2 corresponds to il 2 in FIG. 1, respectively.

In the figure, A shows a normal case, B shows an example in which the transfer is decreased and does not reach the threshold value, and C shows an example in which a large number of received pulses rise due to noise.

The present invention prevents malfunctions that may occur in a snow gauge as shown in FIG. 2, and will be explained below with reference to FIG. 3, which is shown as an example.

In the figure, 1 is a wave transmission clock generation circuit, 2 is an oscillation circuit that generates a tone burst synchronized with the clock of the clock generation circuit 1, 3 is a transmission output amplification circuit, 4 is a transducer, and 5 is a wave transmission 6 is a synchronous reception amplifier synchronized with the clock of generation circuit 5; 7 is a rectifier circuit; 8 is a comparator circuit; A test circuit that tests whether the delivery is normal or not; 10 is a counter that measures the time from wave transmission to wave reception; 11 is a gate that is controlled by the outputs of the generation circuit 5 and the test circuit 9 and allows the output of the counter 10 to pass through; In the circuit, 12 is an output terminal.

Note that there is some correspondence between the signal sequence in FIG. 1 and each circuit in FIG. Output 2 is the output of the comparator circuit 8.

As shown in the above correspondence, an ultrasonic signal is generated by a generation circuit 1, an oscillation circuit 2, and an amplification circuit 3, and is sent by a transducer 4.

The transfer signal is amplified by the generation circuit 5 only during the timing shown in FIG.

In order to verify whether the received signal is normal or not, the verification circuit 9 and gate circuit 11 provided after the circuit 8 function.

The operating state of this verification circuit 9 is shown in FIG.

In the figure, Pl represents the output of the generating circuit 1, Pl represents the output of the comparator circuit 8, and P3 represents the output of the verification circuit.

Further, FIG. 4 shows the specific configuration of the verification circuit 9.
15.18 is an AND circuit, 16 is an inverter,
14 is a 2-bit counter.

As shown in Figure 5, the operation of this circuit is reset when Pl is H, and then when P2 becomes H, the output becomes H once, and if Pl becomes H again after that, the output becomes L. It is.

To explain in more detail, when the output of the generating circuit 1 becomes H, the counter 14 becomes 00.

After that, when an H pulse comes to the comparator 8, the AND circuit 13 increments the counter 14 by one because both signals are H, and this counter 14 becomes 01.

Next, when the output 8 of the comparator circuit becomes H, the counter 1
4 is further IUPed and becomes 10.

After this state, even if an H pulse is input, the AND gate 13 will not match, and the counter 14 will not advance.

The output of the verification circuit 9 is H only when the content of the counter is 01, and is absent under other conditions.

Therefore, if we take the correspondence between each mode shown in Fig. 2 and this circuit, the output when there is one transfer pulse shown in Fig. 2A is the combination of the lines B and the receiving pulse without the H1 transfer pulse. Under the condition C where there are two or more, the output becomes L.

A of the falling edge of the output of the verification circuit 9 and the output of the generation circuit 5
The operation of the gate circuit 11 is to take the ND and output the output from the counter 10 to the output terminal 12.

As described above, according to the present invention, in an ultrasonic snow gauge, the number of transfer pulses between transfer timings is determined and detected under three conditions: none, only one, and two or more. Malfunctions that occur can be effectively and easily removed, and measurement accuracy can be improved.

[Brief explanation of the drawing]

Figure 1 is a signal waveform diagram of a conventional snow gauge, Figure 2 is an abnormal signal waveform diagram of the same snow gauge, Figure 3 is a block diagram of a snow gauge according to an embodiment of the present invention, and Figure 4 is A specific configuration diagram of a part thereof, FIG. 5, is a diagram showing the operating state. 9... Verification circuit, 14... Counter.

Claims (1)

[Scope of utility model registration request] In snow gauges that measure snow depth by measuring the distance to the snow surface from the time interval between ultrasonic wave transmission and delivery, a transfer signal obtained during one wave transmission timing is used in a circuit that detects the presence of transfer. A snow gauge is equipped with a counter that counts the number of times the amplitude of the snow exceeds a certain level, and a circuit that determines that a normal transfer has been made only when this number of times exceeds a certain level.