JPH0123755B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a sludge probe capable of measuring the depth of the sludge layer surface and water bottom surface and the thickness of the sludge layer with high precision.

(Prior Art) Figure 1 shows a conventional sludge probe. First, when the recording pen 2 reaches the recording start point on the recording paper 3 by driving the motor 1 and a synchronization pulse is sent from the synchronization pulse generator 4, the transmission timing circuit 5 sends the synchronization pulse to the transmitters 6 and 7. A timing pulse is issued. The transmitter 6 receives the pulse and creates a pulse-like signal of relatively low frequency f _L ,
The transmitter 7 also generates a pulsed signal of relatively high frequency _fH . The low frequency pulsed signal is sent to the transmitter/receiver switch 8.
The ultrasonic signal is sent to the transducer 10 via the transducer 10, where it is converted into an ultrasonic signal S1 and sent into the water 17. Further, the high frequency pulsed signal is sent to the transducer 11 via the transmitter/receiver switch 9, where the ultrasonic signal S2
It is converted into water and sent into the water 17.

The ultrasonic signal S1 propagates through the water 17 and reaches the sludge layer 1.
8 and is reflected by the water bottom surface 19 to the transducer 1.
0, and the ultrasonic signal S2 is reflected by the sludge layer surface 18a and received again by the transducer 11, but due to the difference in propagation distance, the signal S2
2 is received faster. The received signals are sent to receivers 12 and 13 via transmitter/receiver switchers 8 and 9.
The ultrasonic signals S
Only the frequency components 1 and S2 are extracted and sent to the recording amplifier 16. The recording amplifier 16 amplifies the signals sent from the filters 14 and 15 to a predetermined level and applies it to the recording pen 2 of the discharge breakdown recorder.
The depths of the sludge layer surface 18a and the water bottom surface 19 are recorded on the recording paper 3, respectively.

When using the above device to measure the thickness of the sludge layer 18 with high accuracy and high resolution from the difference in depth between the sludge layer surface 18a and the water bottom surface 19, the frequency f _L of the low-frequency ultrasonic signal S1 must be set to 30 KHz or less. However, in order to obtain such a signal, the transducer 1
0 becomes extremely large, and therefore the transducer 1
This resulted in a deviation of the measurement point between the measurement point and the measurement point, which resulted in a disadvantage that the measurement accuracy deteriorated.

(Object of the Invention) An object of the present invention is to eliminate the above-mentioned conventional drawbacks and to realize a sludge probe capable of measuring the thickness of a sludge layer with high precision and high resolution.

(Structure of the Invention) According to the present invention, when sound waves of two frequencies are simultaneously transmitted to a sound field medium, the sound waves interact with each other due to the nonlinear characteristics of the sound field medium, and the frequency components of the sum and difference of the two frequencies are generated. The aim is to achieve the above-mentioned objective by utilizing the parametric effect in which the frequency component of the difference in this case becomes a sound wave with extremely sharp directivity. The depth of the _sludge layer surface is measured from the propagation time of an ultrasonic signal with a relatively high frequency _f In a sludge probe that measures depth, a first oscillator that creates an ultrasonic transmission signal of the frequency _fH ;
a second oscillator for generating an ultrasonic transmission signal having a frequency f _h that differs from f _H by a frequency f _L ; means for separating the signal components of the frequencies f _H or f _h or f _H and f _h from the signal components of the frequencies f _L from the signals received _by the transducer _; a sludge probe characterized in that two ultrasonic signals of the frequency f _H are simultaneously emitted from the transducer; an oscillator that generates an ultrasonic signal of the frequency f _H ;
a variable frequency oscillator that generates an ultrasonic transmission signal of an arbitrary frequency f _h ' within a predetermined frequency range Δf centered on a frequency f _h that differs from the frequency f L by a frequency f _L ; a means for adding signals to one transducer, and signal components of frequency f _H or f _h ′ or f _H and f _h ′ and frequency (f _H − f _h ′) from the signal received by the one transducer; ), and two ultrasonic signals of the frequencies f _H and f _h ' are simultaneously emitted from the transducer. .

(Example) FIG. 2 shows a first example of the present invention.
Components in the figure that are the same as those in FIG. 1 are denoted by the same reference numerals. That is, 1 is a motor, 2 is a recording pen, 3 is a recording paper, 4 is a synchronous pulse generator, 5 is a transmission timing circuit, 8 is a transmitter/receiver switch, 11 is an ultrasonic transducer, 12 is a receiver, and 14 , 15 is a filter, 16
is a recording amplifier, 17 is underwater, 18 is a sludge layer, 1
8a is the sludge layer surface, 19 is the water bottom surface, 20, 21
is an oscillator, 22 is a synthesis circuit, 23 is a transmitter, 2
4 and 25 are amplifiers.

The oscillator 20 generates a pulsed signal P1 of a relatively high frequency f _H (for example, 100 KHz) that is reflected by the sludge layer surface 18a, and the oscillator 21 generates a pulsed signal P1 having a relatively high frequency f _{H (for example, 100 KHz), which is reflected at the sludge layer surface 18a, and the oscillator 21 generates a signal P1 that can pass through the sludge layer 18 with respect to the frequency f H.} f _L
(e.g. 10KHz) different frequency f _h (e.g.
It is designed to generate a pulse-like signal P2 of 90KHz). Filter 14 extracts a signal component of frequency f _H , and filter 15 extracts a signal component of frequency f _L , which is the difference between frequencies f _H and f _h . Incidentally, since the signal P2 is also reflected by the sludge layer surface 18a, the characteristics of the filter 14 may be such that it extracts the signal component of the frequency f _h , or further, that it extracts the signal component of both the frequencies f _H and f _h . Good too. Further, the combining circuit 22, the transmitter 23, and the transmitter/receiver 8 constitute means for combining the signals P1 and P2 and add them to one transmitter/receiver 11. 15 is one transducer 11
means for separating the signal component of the frequency f _H or f _h or f _H and f _h from the signal component of the frequency f _L from the signal received at the.

Next, the operation will be explained. When the recording pen 2 reaches the recording start point on the recording paper 3 by driving the motor 1 and a synchronization pulse is sent from the synchronization pulse generator 4, a transmission timing pulse is sent from the transmission timing circuit 5 to the transmitters 20 and 21. be done. In response to the pulse, the oscillator 20 generates a pulse-like signal (transmission signal) P1, and the oscillator 21 generates a pulse-form signal (transmission signal) P2, which are sent to the synthesis circuit 2.
Send to 2. The signals P1 and P2 are sent to the combining circuit 2.
2, and is amplified to a predetermined level by the transmitter 23.
will be sent to. The transducer 11 receives the signals P1 and P2.
A pulsed ultrasonic signal SO1 with a frequency f _H
and a pulsed ultrasonic signal SO2 of frequency f _h are simultaneously transmitted.

the two ultrasonic signals SO1 having different frequencies;
When SO2 propagates in the sound field medium, that is, in water 17,
Due to the nonlinearity of the sound field medium, the ultrasonic signals interact with each other, and an ultrasonic signal having a frequency that is the sum and difference of the frequencies of the two signals is generated. At this time, the ultrasonic signal SO3 having the difference frequency f _L (=f _H - f _h ) has sharp directivity.

The ultrasonic signals SO1 and SO2 propagate through the water 17,
The transducer 11 is reflected by the sludge layer surface 18a.
However, the ultrasonic signal SO3 passes through the sludge layer 18, is reflected by the water bottom surface 19, and is also received by the transducer 11. These signals are sent to the receiver 12 via the transmitter/receiver switch 8, where they are amplified to a certain level and then passed through the filters 14 and 1.
Sent on 5th. The filter 14 extracts the frequency f _H component, that is, the received signal of the ultrasonic signal SO1,
Further, the filter 15 extracts the frequency f _L component, that is, the received signal of the ultrasonic signal SO3, and these are amplified to a predetermined level by amplifiers 24 and 25, respectively. However, the efficiency with which the ultrasonic signal SO3 is formed is low, and in order to correct the frequency characteristics of the transducer 11, the amplifiers 24 and 25 are set to different amplification degrees. The recording amplifier 16 further amplifies the received signal, which has been amplified to almost the same level by the amplifiers 24 and 25, to a level necessary for recording.
A voltage is applied to the recording pen 2 to form a sludge layer surface 1 on the recording paper 3.
8a, record the depth of the water bottom surface 19. The thickness of the sludge layer 18 can be measured by reading the difference between the depth of the sludge layer surface 18a and the depth of the water bottom surface 19 from this recorded result.

In this way, according to the above embodiment, two ultrasonic signals with relatively high frequencies are simultaneously transmitted, and due to the parametric effect, ultrasonic signals are transmitted at a relatively low frequency corresponding to the frequency difference between the two signals, and with directivity. Because it generates sharp ultrasonic signals and measures the depth of the sludge layer surface and water bottom, there is no need for a transducer that generates low frequency ultrasonic signals.
It is possible to eliminate the deviation in measurement points between high frequency signals and low frequency signals, and therefore the depth of the sludge layer surface and the depth of the water bottom at the same point can be recorded on the same axis on the recording paper. , it is possible to measure the thickness of the sludge layer with high precision.

Note that the frequency components of the sum and difference between frequencies f _H and f _h may be generated not only underwater but also due to the nonlinearity of the transmitter 23, so it is necessary to pay sufficient attention to this point and suppress them in advance. .

FIG. 3 shows a second embodiment of the present invention,
Here, the frequency of one of the relatively high frequency ultrasonic signals is made variable. In other words, 2 in the figure
6 is a variable frequency oscillator, 27 is a variable frequency filter, and the variable frequency oscillator 26 is a variable frequency oscillator.
It is now possible to create a transmission signal of any frequency f _h ' within a predetermined frequency range Δf centered on f _h ,
The variable frequency filter 27 is the variable frequency oscillator 26
The frequency f _L ′ (= f _H − f _h ′) according to the oscillation frequency of
It is constructed so that the signal can be extracted. According to such a configuration, the frequency of the ultrasonic signal SO3 can be selected depending on the deposition state of the sludge layer, the soil quality of the water bottom, etc., and it becomes possible to probe a wider range of the sludge layer with high precision. Note that the synthesis circuit 2
2. The transmitter 23 and the transmitter/receiver switch 8 combine the transmitting signal of the frequency f _H and the transmitting signal of an arbitrary frequency f _h ' within a predetermined frequency range Δf centered on the frequency f _h to form one transmitter/receiver. The transmitter/receiver switch 8, the receiver 12, the filter 14, and the variable frequency filter 27 select the frequency f _H or f _h ′ or f from the signal received by the transducer 11. _H and
A means is configured to separate the signal component of f _h ′ and the signal component of frequency (f _H −f _h ′), respectively. Further, the other configurations and effects are similar to those of the first embodiment.

(Effects of the Invention) As explained above, according to the present invention, the depth of the sludge layer surface is measured from the propagation time of the ultrasonic signal of relatively high frequency f _H reflected on the sludge layer surface, and the sludge layer surface depth is measured. In a sludge probe that measures the depth of the water bottom surface based on the propagation time of an ultrasonic signal with a relatively low frequency f _L passing through the sludge probe, a first oscillator that generates an ultrasonic transmission signal with a frequency f _H ; frequency
a second oscillator for generating an ultrasonic transmission signal having a frequency f _h that differs from f _H by a frequency f _L ; means for separating the signal components of the frequencies f _H or f _h or f _H and f _h from the signal components of the frequencies f _L from the signals received _by the transducer _; Since the two ultrasonic signals are simultaneously transmitted from the transducer,
Due to the parametric effect, it is possible to generate ultrasonic signals with a relatively low frequency corresponding to the frequency difference between the two signals and with sharp directivity. The device can be miniaturized without the need for a transducer, and it is also possible to eliminate the shift in the transmission points of high and low frequency ultrasonic signals. The depth of the surface of the sludge layer and the depth of the bottom surface of the water can be recorded on the same axis on recording paper, making it possible to measure the thickness of the sludge layer with high precision and high resolution. Further, an oscillator for creating an ultrasonic transmission signal of frequency f _H , and an oscillator for generating an ultrasonic transmission signal of frequency f _H
a variable frequency oscillator that generates an ultrasonic transmission signal of an arbitrary frequency f _h ' within a predetermined frequency range Δf centered on a frequency f _h that differs from the frequency f L by a frequency f _L ; a means for adding signals to one transducer, and signal components of frequency f _H or f _h ′ or f _H and f _h ′ and frequency (f _H − f _h ′) from the signal received by the one transducer; ), and the two ultrasonic signals of the frequencies f _H and f _h ' are simultaneously emitted from the transducer, the above-mentioned effects can be achieved. Of course, there are advantages in that the frequency of the low-frequency ultrasonic signal can be changed arbitrarily, and highly accurate measurements can be made depending on the state of the sludge layer and the bottom of the water.

[Brief explanation of drawings]

The drawings serve to explain the present invention; FIG. 1 is a block diagram showing a conventional sludge probe, FIG. 2 is a block diagram showing a first embodiment of the sludge probe of the present invention, and FIG. FIG. 3 is a block diagram showing a second embodiment of the present invention. 1... Motor, 2... Recording pen, 3... Recording paper, 4... Synchronous pulse generator, 5... Transmission timing circuit, 8... Transmission/reception switch, 11... Transducer/receiver, 12... Reception vessel, 14, 15...filter,
16... Recording amplifier, 17... Underwater, 18... Sludge layer, 18a... Sludge layer surface, 19... Water bottom surface, 20, 21... Oscillator, 22... Synthesis circuit,
23... Transmitter, 24, 25... Amplifier, 26...
...Variable frequency oscillator, 27...Variable frequency filter.

Claims (1)

[Claims] 1. The depth of the sludge layer surface is measured from the propagation time of an ultrasonic signal with a relatively high frequency f _H reflected on the sludge layer surface, and the relatively low frequency f _L passing through the sludge layer is measured. In a sludge probe that measures the depth of the water bottom based on the propagation time of an ultrasonic signal, the frequency f _H
a first oscillator that generates an ultrasonic transmission signal;
A frequency that differs from the frequency f _H by the frequency f _L
a second oscillator for generating an ultrasonic transmission signal f _h ; a means for combining the two transmission signals and applying the signal to one transducer; and means for separating signal components of frequencies f _H or f _h or f _H and f _h and signal components of frequencies f _L , and transmits the two ultrasonic signals of frequencies f _H and f _h to the transducer. A sludge probe that is characterized by transmitting signals more simultaneously. 2. Measure the depth of the sludge layer surface from the propagation time of the ultrasonic signal with a relatively high frequency f _H reflected on the sludge layer surface, and measure the propagation of the ultrasonic signal with a relatively low frequency f _L passing through the sludge layer. In a sludge probe that measures the depth of the water bottom surface based on time, the frequency f _H
an oscillator that generates an ultrasonic transmission signal, and an arbitrary frequency f _{h ′} within a predetermined frequency range Δf centered on a frequency f _h that differs from the frequency f H by a frequency f _L.
a variable frequency oscillator for generating an ultrasonic transmission signal; a means for synthesizing the two transmission signals and applying it to one _transducer ; or means for separating the signal component of f _h ′ or f _H and f _{h ′} from the signal component of frequency (f _{H −f h} ′),
A sludge probe characterized in that two ultrasonic signals f _h ' are transmitted simultaneously from the transducer.