JPH0449668B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a sludge probe that measures the layer thickness of sludge deposited on the bottom of an ocean.

[Conventional technology]

When two frequency sound waves are simultaneously transmitted to the sound field medium,
A sound wave interaction is caused by the nonlinear characteristics of the sound field medium, and frequency components of the sum and difference of the two-frequency sound waves are generated. In this case, the frequency component of the difference becomes a sound wave with extremely sharp directivity, and this phenomenon is called a parametric effect.

A sludge probe that uses such parametric effects to measure the layer thickness of sludge deposited on the bottom of the water has been proposed. A relatively high frequency ultrasound signal reflected by
A relatively low-frequency ultrasonic signal that passes through the sludge layer is transmitted toward the water bottom, and the depth from the transducer to the sludge surface and the depth from the transducer to the water are determined based on the difference in the propagation time of each ultrasonic signal. By obtaining and recording the depth to the bottom surface, the thickness of the sludge layer can be measured.

FIG. 1 is a block diagram showing a conventional sludge probe of this type, and FIG. 2 is a diagram showing an example of recording by this sludge probe.

In Figure 1, 1 is a motor, 2 is a recording pen, and 3 is a motor.
is a recording paper, 4 is a synchronous pulse generator, 5 is a transmission timing circuit, 6 is a first oscillator, 7 is a second oscillator, 8 is a synthesis circuit, 9 is a transmitter, 10 is a transmitter/receiver switch, 11 is a transmitter/receiver 12 is the receiver, 13 is the first
14 is a second filter, 15 is a first amplifier, 16 is a second amplifier, 17 is a recording amplifier, 18 is underwater, 19 is a sludge surface, and 20 is a bottom surface of the water.

In addition, H in the figure is the depth from the transducer 11 to the sludge surface, L is the depth from the transducer 11 to the bottom surface of the water, and the dotted line from the transducer 11 is the first ultrasonic wave with a different frequency. A sound wave and a second ultrasound wave are shown.

Next, the operation of the above-described configuration will be explained.

A belt is moved by a motor 1, and when a recording pen 2 provided on the belt reaches a recording start point on a recording paper 3, a synchronous pulse generator 4 generates a pulse.

Based on this pulse, the transmission timing circuit 5 determines the transmission timing, and the first oscillator 6 generates a relatively high first frequency _H (for example, 100KHz) pulse signal, and the second oscillator 7 generates the first pulse signal. A second frequency _L lower than the frequency _H (e.g. 90KHz)
oscillates a pulse signal.

These two pulse signals of frequencies _H and _L are combined by a combining circuit 8, amplified to a constant level by a transmitter 9, and then applied to a transducer 11 through a transmitter/receiver switch 10.

The transducer 11 converts the pulse signal into an ultrasonic signal, and this ultrasonic signal is transmitted into the water 18 toward the bottom of the water.

The ultrasonic signal transmitted into the water 18 in this way is
The ultrasonic signal propagates through the water 18 and is reflected by the sludge surface 19, and furthermore, the ultrasonic signal having the difference frequency component generated by the parametric effect passes through the sludge layer and is reflected by the bottom surface 20 of the water.

Each of the ultrasonic signals resulting from this reflection is received by a transducer 11, converted into an electrical signal, and then sent to a receiver 12 via a transceiver switch 10, which converts it to a certain level. The signal is amplified and sent to the first filter 13 and the second filter 14.

Here, the first filter 13 has a first frequency
Pass only _{the H} signal, and also pass through the second filter 1
4 passes only the signal of the second frequency _L.

As a result, both signals are separated, and the first frequency _H signal passed through the first filter 13 and the second frequency H signal passed through the first filter 13 are separated.
The signal of the second frequency _L that has passed through the filter 14 is transmitted to the first amplifier 15 and the second amplifier 1, respectively.
6, the signals are amplified to a certain level, and furthermore, these two signals are added and amplified by a recording amplifier 17, and then given to the recording pen 2.

The recording pen 2 records the transmitting point of the ultrasonic signal on the recording paper 3 at the recording start point, and then moves while the ultrasonic signal is propagating underwater, and as described above, the recording amplifier 17 The reception time point is recorded on the recording paper 3 by the signal given from.

Therefore, as shown in FIG. 2, the difference in the position of the recording pen 2 at the time of transmitting and receiving the ultrasonic signal is recorded on the recording paper 3 as depths H and L. The sludge layer thickness is measured from the difference between depths H and L.

However, in such a conventional sludge probe, the first signal handled by the receiving system including the transducer 11, the first filter 13, the second filter 14, the first amplifier 15, and the second amplifier 16 is frequency
Since the frequency characteristics of _{the H} signal and the second frequency _L signal are about 10 times different, the transducer 11, the first filter 13, the second filter 14, and the first amplifier 15 , and second amplifier 16
A time error occurs due to the difference in the frequency characteristics of the two signals, and this time error is reproduced as it is on the recording paper, making accurate measurement impossible.

[Purpose of the invention]

The present invention has been made to solve these drawbacks of the prior art, and aims to realize a sludge probe that can accurately measure the layer thickness of sludge.

[Structure of the invention]

To achieve this objective, the present invention provides a signal of a first frequency that is oscillated by a first oscillator and reflected on the sludge surface, and a signal of a first frequency that is oscillated by a second oscillator that passes through the sludge and is reflected on the bottom surface of the water. A signal of a second frequency is synthesized and added to a transducer, and the transducer simultaneously transmits an ultrasonic wave of a first frequency and an ultrasonic wave of a second frequency toward the bottom of the water based on the synthesized signal. Then, the ultrasonic waves reflected on the sludge surface and the ultrasonic waves reflected on the bottom surface of the water are received by the transducer, and the received ultrasonic signals are filtered to a first frequency by a first filter and a second filter. The signals are separated into a signal and a signal of a second frequency, and amplified by a first amplifier and a second amplifier, respectively. In the sludge probe that measures the layer thickness of sludge by recording the depth from the transducer to the sludge surface and the water bottom surface on recording paper with a recording pen based on a time difference, at least one of the first amplifier and the second amplifier. A delay circuit is connected to the transmitter/receiver, the first and second filters, and the first and second filters by this delay circuit.
The present invention is characterized in that a time error resulting from a difference in frequency characteristics between a first frequency signal and a second frequency signal is corrected within the amplifier.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 3 is a block diagram showing an embodiment of the sludge probe according to the present invention, in which 1 is the motor 2.
3 is a recording pen, 3 is a recording paper, 4 is a synchronous pulse generator, 5 is a transmission timing circuit, 6 is a first oscillator, 7 is a second oscillator, 8 is a synthesis circuit, 9 is a transmitter, 10 is a transmission/reception switch 11 is a transducer, 12 is a receiver, 13 is a first filter, 14 is a second filter, 15 is a first amplifier, 16 is a second amplifier, 17 is a recording amplifier, 18 is underwater, 19 is the sludge surface, 20 is the water bottom, H is the depth from the transducer 11 to the sludge surface 19, and L is the transducer 11.
to the bottom surface 20, and since these correspond to conventional ones, they are indicated by the same reference numerals.

Further, the dotted lines from the transducer 11 also indicate first ultrasonic waves and second ultrasonic waves having different frequencies, as in the conventional case.

21 is a first delay circuit, 22 is a second delay circuit, and their respective input sides are connected to the first amplifier 15 and the second delay circuit.
It is connected to the output side of an amplifier 16, and the output side is connected to the input side of a recording amplifier 17 via a variable switch.

Next, the operation of the above-mentioned configuration will be explained.
In this embodiment, the operation from the movement of the recording pen 2 by the motor 1 to the amplification output of the first frequency _H signal and the second frequency _L signal by the first amplifier 15 and the second amplifier 16 is conventional. Since it is performed in the same manner as , the explanation thereof will be omitted.

The signal of the first frequency _H and the signal of the second frequency _L are transmitted from the transducer 11 included in the receiving system to the first filter 13 and the second filter 14 to the first amplifier due to the difference in their frequency characteristics. 15 and the second amplifier 16, a time error occurs internally due to the difference in the frequency characteristics of the two signals, and while this time error is retained, the first
A signal with a frequency _H and a signal with a second frequency _L are input to the first delay circuit 21 and the second delay circuit 22, respectively.

A waveform diagram in this case is shown in FIG.

Here, the first
Let the signal of frequency _H be A, and the second delay circuit 22
Let B be the signal of the second frequency _L that is input to the .

In a recording system in which the recording pen 2 is set to record at a constant level, signal A with a higher frequency, that is, the first frequency _H , is higher than signal B with a lower frequency, that is, the second frequency _L , even for the same rising wave number. It will be recorded early.

For example, as shown in Figure 4, the wave of signal A of the first frequency _H from the time of transmission until it is recorded is
If TH and the wave of signal B at the second frequency _L are TL, it can be seen that a time error of "TH-TL" occurs.

This time error is the cause of measurement errors in the past.

Therefore, in this embodiment, this time error is corrected by the first delay circuit 21 and the second delay circuit 22 and outputted to the recording amplifier 17 at the subsequent stage.

Therefore, the first delay circuit 21 and the second delay circuit 22 are preset with a delay amount for correcting the time error of the "TH-TL". The second delay circuit 22 corrects the temporal error.

The first delay circuit 21 and the second delay circuit 22
The delay amount can be set as follows.

That is, if a rigid body is placed in water and an ultrasonic signal is reflected from this rigid body, the reflection in this case does not differ depending on the frequency of the ultrasonic signal, so it will indicate the same depth. Therefore, using this principle, the first delay circuit 21 and the second delay circuit 21 are connected so that the signal of the first frequency _H and the signal of the second frequency _L reflected by the rigid body appear at the same position on the recording paper 3. The delay amount of the delay circuit 22 is set.

In this way, the first delay circuit 21 and the second delay circuit 22 correct the time error between the signal of the first frequency _H and the signal of the second frequency _L , and output the corrected signal to the recording amplifier 17 at the subsequent stage. The recording amplifier 17 adds and amplifies the two signals, and supplies the amplified signals to the recording pen 2, thereby recording the reception time on the recording paper 3.

Note that in the embodiment described above, the first delay circuit 21
and the second delay circuit 22 to correct the time error of "TH-TL"; however, it is also possible to correct the time error using only one of them; in this case, the other The delay circuit can be omitted.

In the case of the above embodiment, since recording can only be delayed, the depths H and L recorded on the recording paper 3, the absolute value of the depth H from the transducer 11 to the sludge surface 19, and Transducer/receiver 11
A fixed error will occur between the depth L and the bottom surface 20, but this can be solved by shifting the scale on the recording paper 3 or by shifting the scale to read. Accurate measurement becomes possible.

FIG. 5 is a block diagram showing another example of a delay circuit, in which 23 is an analog/digital converter, 24, 25, 26, and 27 are shift registers, and 28, 29, 30, and 31 are shift registers. Switches 24 to 27 select the output of each bit, and 32 is a digital/analog converter.

In this delay circuit, first, the analog/digital converter 23 converts the signal of the first frequency _H or the signal of the second frequency _L from the first delay circuit 21 or the second delay circuit 22 from the analog signal, for example. It is converted into a 4-bit digital signal and input to shift registers 24-27.

If the shift length per bit of the shift registers 24 to 27 is n and the gap between shift pulses at ₀ bits is T seconds, the delay time at a bit at an arbitrary point n is naturally nT seconds, so the shift register is By selecting the output of the n-th bit from 24 to 27 with switches 28 to 31, the signal of the first frequency _H or the signal of the second frequency _L is output.
Can be delayed by nT seconds.

This delay time nT seconds may be set to be equivalent to the time error of "TH-TL" explained with reference to FIG. 4 above.

In this way, the time error can be corrected in the same way as the first delay circuit 21 or the second delay circuit 22 shown in FIG.

The signal of the first frequency _H or the signal of the second frequency _L after the correction is converted from a digital signal to an analog signal again by the digital/analog converter 32, and is sent to the recording amplifier 17, so that it can be printed on the recording paper 3 by the recording pen 2. Recordings are made above.

〔Effect of the invention〕

As explained above, the present invention provides a first amplifier and a second amplifier that amplify a first frequency signal and a second frequency signal separated by a first filter and a second filter of a receiving system. A delay circuit is connected to at least one of the signals, and the delay circuit allows the signals of the first frequency and the signals of the second frequency to be separated in the transducer, the first and second filters, and the first and second amplifiers. Since the configuration corrects time errors caused by differences in frequency characteristics, the depth from the transducer to the sludge surface and water bottom can be accurately recorded on the recording paper, which allows for accurate sludge layer thickness. The effect of being measurable can be obtained.

[Brief explanation of the drawing]

Figure 1 shows a block diagram of a conventional sludge probe.
FIG. 2 is a diagram showing an example of recording by the sludge probe in FIG. 1, FIG. 3 is a block diagram showing an embodiment of the sludge probe according to the present invention, and FIG. FIG. 5 is a block diagram showing another example of the delay circuit used in the present invention. 2... Recording pen, 3... Recording paper, 6... First oscillator, 7... Second oscillator, 8... Synthesis circuit,
11... Transducer/receiver, 13... First filter,
14... Second filter, 15... First amplifier, 16... Second amplifier, 17... Recording amplifier, 19... Sludge surface, 20... Water bottom surface, 21
...first delay circuit, 22...second delay circuit,
23...Analog/digital converter, 24-27
...Shift register, 28-31...Switch,
32...Digital/analog converter.

Claims (1)

[Claims] 1. A first frequency signal that is oscillated by a first oscillator and reflected on the sludge surface, and a second frequency signal that is oscillated by a second oscillator and that passes through the sludge and is reflected on the water bottom surface. The signals are combined and applied to a transducer, and the transducer simultaneously transmits ultrasonic waves of a first frequency and ultrasonic waves of a second frequency based on the synthesized signals toward the water bottom to remove sludge. The ultrasonic waves reflected on the surface and the ultrasonic waves reflected on the bottom surface of the water are received by the transducer, and the received ultrasonic signals are passed through a first filter and a second filter into a first frequency signal and a second frequency signal. The signals are separated into signals of a frequency of , and amplified by a first amplifier and a second amplifier, respectively. In a sludge probe that measures the layer thickness of sludge by recording the depth from the wave probe to the sludge surface and the water bottom on recording paper with a recording pen, a delay circuit is provided in at least one of the first amplifier and the second amplifier. The delay circuit connects the transducer, the first and second filters, and the first,
A sludge probe characterized in that a time error resulting from a difference in frequency characteristics between a first frequency signal and a second frequency signal is corrected within a second amplifier.