JPH1090410A - Geological survey equipment - Google Patents

Abstract

(57) [Summary] [PROBLEMS] When scanning sideways with a parametric ultrasonic transmitter, the width of a main lobe is increased and side lobes are also generated. A by transmitting ultrasonic waves of frequency f ₁ than this lower frequency f ₂ at the same time, thereby 2 obtained order frequency
In a stratum exploration device that performs stratum exploration based on the echo of the ultrasonic signal (f ₁ −f ₂ ), the phase of the ultrasonic wave transmitted by each transducer of the transmitter (S) is to be scanned in an arbitrary direction. comprising means (8) for controlling, by said means, when the beam scanning in the theta direction, the ultrasonic scan azimuth frequency f ₁ and (theta + beta), ultrasound scanning azimuth frequency f ₂
The (θ-β) and then, said means, when the beam scanning in the -θ direction, the ultrasonic scan azimuth frequency f ₁ (-
and theta-beta), an ultrasound scan azimuth frequency f ₂ (-
θ + β) to reduce the beam width of the main lobe and suppress the generation level of the side lobe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a geological survey device using a parametric ultrasonic transmitter.

[0002]

2. Description of the Related Art In a geological survey device for exploring the geology under the sea floor or a buried submarine cable, a low-frequency wave having a high permeability of about 10 kHz is used for ultrasonic waves transmitted toward the sea floor.

In an ultrasonic transducer that emits low-frequency ultrasonic waves, a beam (main beam) is intended to have a desired directional angle (narrow beam width) in order to increase detection resolution. For example, since the size is inversely proportional to the ultrasonic frequency, the low-frequency transducer becomes extremely large in size and is not practical.

[0004] Therefore, a parametric ultrasonic transducer that can be made compact even for low frequencies is provided. The detailed configuration and operation of the parametric ultrasonic transducer are disclosed in Japanese Patent Publication No. 1-16391 by the present applicant, but will be briefly described here.

FIG. 1 shows a parametric ultrasonic transmitter S and an ultrasonic receiver R used together with the transmitter S. Note that the parametric ultrasonic transducer disclosed in the above publication has a structure in which ultrasonic vibration elements are radially arranged concentrically because beam scanning is not assumed.
In the transmitter S, ultrasonic transducers and ● are arranged in a grid pattern for performing beam scanning. The ultrasonic transducers used here are both ultrasonic transducers for high frequency (hence the size is small), are arranged in 16 rows and columns, ● is located between each, and 16 rows and columns are similarly Are arranged. Each of the sixteen vibrators arranged vertically is connected to each other, and has a frequency f
₁ (100kHz) ultrasonic power signal, and ● shows frequency f ₂ (90k
Hz) ultrasonic power signals are supplied via phase shifters. As shown in FIG. 2, the transmitter S and the receiver R are mounted on the ship bottom with the transmitting / receiving surface facing downward.

Now, when the delay in each phase shifter is set to 0, ultrasonic waves of 100 kHz and 90 kHz are radiated downward and in phase from each ultrasonic transducer. The two emitted ultrasonic waves are synthesized underwater, and the added component (100 + 90) kHz
And an ultrasonic wave having a difference component of (100-90) kHz is generated, and the ultrasonic wave having a difference component of 10 kHz is provided for geological exploration. The directional characteristics of the 10 kHz ultrasonic wave are similar to the directional characteristics when radiating the ultrasonic waves of 100 kHz and 90 kHz from the ultrasonic vibrators 、 and ●, and therefore have a small size for high frequency and excellent directional characteristics. It can be a frequency transmitter.

[0007] However, since receivers R is for reception of the low frequency signal of 10 kHz, the total length L ₃ is greater than the length L ₂ of the transmitters S, the receivers as illustrated in FIG 2 R by,
In order to make the beam width θp in the traveling direction the same as the beam width θn of the transmission beam, it is theoretically L ₃ = 10L ₂ , which is not practical. Therefore, L ₃ is actually made about three times longer than L _2. You.

Since the 190 kHz added signal has a large attenuation and is not suitable for underground exploration, it is removed by a filter provided in the receiving system. While the frequency of the original transmitted signal is called the primary frequency, the frequency of the ultrasonic wave obtained as the difference component is called the secondary frequency.

FIG. 3 shows the beam characteristics in the azimuth direction when the ultrasonic wave is transmitted only under the conditions of a transmission frequency of 100 kHz and a sound speed of 1500 m / s. The beam width θ ₁₀₀ of the main lobe was 7.08 ° (−3 dB).

FIG. 4 shows the beam characteristics in the downward direction when only the ultrasonic transducer indicated by ● is used, the transmission frequency is 90 kHz, and other conditions are the same as those in FIG. The beam width θ ₉₀ of the main lobe was 8.10 ° (-3 dB).

The above primary frequency (100 kHz and 9 kHz)
0 kHz) which is obtained when the transmission signals are transmitted simultaneously.
FIG. 5 shows a simulation of a beam characteristic in a direction directly below by an ultrasonic wave having a next frequency (10 kHz). This figure 5
As you can see, the beam width theta ₁₀ of the main lobe is almost the same as that of FIG. 3, according to the parametric ultrasonic transducer, using an ultrasonic wave transmitter of the small (for 100kHz) Thus, a low frequency (10 kHz) ultrasonic wave can be transmitted with desired directional characteristics. That is, as shown in FIG. 2, if the beam width at the time of transmitting an ultrasonic wave of 100 kHz using the transmitter S is θm and θn as shown in FIG. A wave beam is formed.

In order to search a wide area by using a geological survey device, it is necessary to oscillate (scan) a beam not only in a direction directly below but also in a lateral direction. As is well known, a fixed amount of delay is set between adjacent phase shifters to scan a beam. That is, as shown in FIG. 1, when forming a directivity beam in the θ direction, when the second path difference of transmitters A ₂ relative to the first wave transmitter A ₁ is ΔL shorter than in the A ₁ , A ₂
The transmission timing, Okurashi by the time difference Δt which corresponds to [Delta] L (phase difference [Delta] [theta]), 3-th wave transmitter A ₃ are, (2? T than the A ₁₎ the time difference Δt as compared to A ₂ by delay.

FIGS. 6 and 7 show beam directivity characteristics when beam scanning is performed at a transmission angle of 45 ° in FIGS. 3 and 4. FIG. Naturally, the main lobe M is generated in the 45 ° direction, and the main lobe has a wider beam width as compared with the main lobe in FIGS. The reason is that, as shown in FIG. 1, the effective aperture length L ₁ ′ of the transmitter S when the beam is scanned is different from the aperture length L ₁ of the transmitter S when the beam is transmitted in the downward direction. Is shortened. FIG.
In FIG. 7, a side lobe S is generated in the azimuth of -30.degree., And in FIG. 7, the side lobe S is generated in an azimuth of -34.degree., And both levels are higher than the main lobe.

[0014]

Problems to be Solved by the Invention 1 in FIGS.
FIG. 8 shows the beam characteristics in the azimuth direction by the ultrasonic waves of the secondary frequency (10 kHz) obtained when the transmission signals of the secondary frequencies (100 kHz and 90 kHz) are transmitted simultaneously. As can be seen from FIG. 8, the beam width of the main lobe M is almost the same as that of FIGS. 6 and 7, and the detection resolution is reduced because the beam width is slightly wider than that of the transmission directly below. Although the side lobe S is suppressed as compared with FIGS. 6 and 7, it occurs at a considerably high level.
If the generation level of the side lobe is high, the detection signal of the weak level is buried in the signal of the side lobe, and the signal of the low level cannot be detected, so that not only the dynamic range is reduced, but also the image is displayed twice. Blurred. Therefore, the conventional parametric transmitter S has a problem that it is suitable only for exploration in a direction directly below.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a geological exploration apparatus that does not expand a main lobe even when a beam is scanned and that can suppress the generation level of a side lobe. The purpose is to provide.

[0016]

Means for Solving the Problems The first invention (Claim 1)
Transmits an ultrasonic wave having a frequency f ₁ and an ultrasonic wave having a frequency f ₂ lower than the frequency f ₁ at the same time, and obtains a secondary frequency (f ₁ −f ₂ ) obtained thereby.
In a geological exploration machine that performs geological exploration based on the echo of the ultrasonic signal, a means for controlling the phase of ultrasonic waves transmitted by each transducer of the transmitter to perform beam scanning in an arbitrary direction, , When beam scanning in the θ direction,
The ultrasound scan azimuth frequency f ₁ and (θ + β), the ultrasonic scanning direction of the frequency f ₂ and (θ-β), the said means, when the beam scanning in the -θ direction, the frequencies f ₁ Ultra The scan azimuth of the sound wave is set to (−θ−β), the scan azimuth of the ultrasonic wave of frequency f ₂ is set to (−θ + β), and the beam width of the main lobe is narrowed.

According to a fourth aspect of the present invention, there is provided an ultrasonic transmitter (S) including a first ultrasonic vibrator group (A) and a second ultrasonic vibrator group (B); A frequency f ₁ supplied to each of the ultrasonic transducer groups (A) and (B) so as to individually form a transmission beam in a desired direction in each of the ultrasonic transducer groups (A and B), and Phase ROM that stores an ultrasonic signal having a low frequency f ₂ as sampling data for each of the directions.
(1) and (1 ′), the first ultrasonic transducer group (A) and the second ultrasonic transducer group (B) are used to set the frequency f ₁ and the azimuth of the desired scan command angle θ to the desired direction. and transmitting ultrasonic waves of a frequency f ₂ at the same time, thereby resulting secondary frequency (f ₁ -f ₂₎
A stratum exploration apparatus which receives an echo of the ultrasonic signal of (1) by an ultrasonic wave receiver (R) and performs stratum exploration, and in the phase ROM (1), (θ + β) with respect to the desired scan command angle θ. The phase ROM (1 ') reads data in the (θ-β) direction, and the phase ROM (1) reads data in the (-θ-β) direction for the scan command angle -θ. ,
The phase ROM (1 ′) is characterized in that corresponding data is stored in each of the phase ROMs (1) and (1 ′) so that data in the (−θ + β) direction can be read.

[0018]

[Action] and transmitting ultrasonic waves of frequency f ₁ than this lower frequency f ₂ at the same time, thereby resulting secondary frequency (f ₁ -
f ₂ ) In a geological survey device that performs a geological survey based on the echo of the ultrasonic signal, when the beam is scanned laterally as described above, the beam width of the main lobe is wider than when the beam is transmitted directly downward. And the detection resolution decreases.
In the present first invention is therefore, when the beam scanning in the theta direction, the ultrasonic scan azimuth frequency f ₁ and (θ + β), and an ultrasonic scan direction of the frequency f ₂ and (θ-β), by the means , when the beam scanning in the - [theta] direction, by an ultrasonic scan direction of the frequency f ₁ and (- [theta]-beta), the ultrasonic scanning direction of the frequency f ₂ and (-θ + β), in this case In the obtained ultrasonic signal of the secondary frequency, the beam width of the main lobe is narrowed, so that the detection resolution does not decrease even when the beam is scanned sideways.

In the above-described geological exploration apparatus, when scanning is performed laterally, side lobes appear, and a double image is formed. Here, the generation level of the side lobe is suppressed by shifting the scan azimuth similarly to the case of the first aspect. Therefore, this configuration is claimed in claim 2.

As can be seen from the above description, the beam width of the main lobe can be reduced and the generation level of the side lobe can be reduced by shifting the scan azimuth as in the case of the first aspect. Charged at 3.

A geological exploration apparatus according to the present invention is described in claim 4, and a more specific configuration is described in detail in the following embodiments.

[0022]

FIG. 9 is a control block diagram showing an embodiment of a wave transmitting section of the geological survey device of the present invention. S is for Figure 1
This is the same as the parametric ultrasonic wave transmitter S shown by. 1 is a phase ROM for storing data of the ultrasound signals for exciting the ultrasonic transducer A ₁ to A ₁₆ in 100kHz. 1 '90kH ultrasonic transducer B ₁ .about.B ₁₆
This is a phase ROM that stores data of an ultrasonic signal to be excited in z. The data stored in these phase ROMs 1 and 1 'will be described with reference to FIGS.

The 16 phase ROMs ₁ have amplitude values a ₁ , a ₂ , a ₃ ,..., A ₁₇ and a ₁₈ as shown in FIG.
Eight data are stored. If these data are repeatedly read out at a predetermined speed as a ₁ → a ₂ → a ₃ →... A ₁₇ → a ₁₈ → a ₁ → A phase signal is obtained, and an ultrasonic signal of the same phase is supplied to each of the ultrasonic transducers A ₁ to A _16.
A transmission beam of Hz is formed.

A total of 18 data of the amplitude values a ₁ , a ₂ , a ₃ ,... A ₁₇ , a ₁₈ are also stored in the phase ROM 1 ′ of another group, and these data are stored at the predetermined speed. A ₁ → a ₂ → a ₃ → ... → a ₁₇ → a ₁₈ → at 9/10 times speed
If it is read repeatedly as a ₁ →, each will be 90kHz
As a result, a signal of z is obtained, and a transmission beam of 90 kHz is formed in a downward direction by each of the ultrasonic transducers B ₁ to B ₁₆ .

Therefore, in order to form a beam directly below,
Each phase ROM1,1 'stores a data of a ₁ ~a _18.

On the other hand, as shown in FIG.
When a transmission beam is formed in a direction having an angle of (hereinafter referred to as a scan command angle θ), a path difference (Δt in time difference) is shorter in the ultrasonic vibrator A ₂ than in the ultrasonic vibrator A _1. wave oscillator A ₃ in short time difference 2? t, it is shorter ultrasonic transducer A ₁₆ at time difference 15Derutati. Therefore, the phase ROM _{1 corresponding} to the ultrasonic transducer A ₁ stores the data (the first amplitude data a ₁ is the level 0
), The phase ROM ₁ for the ultrasonic transducer A2 holds data delayed by a phase difference Δθ ₁ corresponding to the time difference Δt from the data.

Therefore, the transmission beam is shifted from -45 ° to 0 to +4.
When scanning a 5 ° scan range at a 1 ° pitch, it is necessary to store 91 types of waveform data in each phase ROM 1, 1 ′. However, in the present apparatus, the scanning is not performed according to the scan command angle θ (−45 ° to 0 to + 45 °). Since the angle is offset only by the offset, the waveform data corresponding to the offset angle is stored. This offset will be described in detail later.

2 and 2 'shown in FIG.
The ultrasonic signals read from 1, 1 'are amplified in power and supplied to the ultrasonic transducers A and B. Reference numeral 3 denotes a clock pulse generator that generates a basic clock in the present apparatus. Reference numeral 4 denotes a frequency divider, which is composed of an L-ary counter that outputs a pulse each time the clock output from the clock pulse generator 9 is counted by an L value. This L is given as a range setting value that determines the search range Lr shown in FIG.

Reference numeral 5 shown in FIG. 9 is a distance counter.
This is an M-ary counter that counts output pulses from the frequency divider 4 from 0 to (M−1), and the count value indicates the distance from the transmitter S. Here, the relationship between the pulse periods τ, L and M output from the clock pulse generator 3 is, for example, 1500 m / s for underwater sound speed, 1/750000 s for period τ, and 1000 for M.
Then, when the range is 50 m, L = 50 from 50/2/1500 = LM / 750000.

Numeral 6 shown in FIG. 9 denotes an azimuth counter which outputs a trigger pulse output from the distance counter 5 in a scan range.
(−45 ° to 0 ° to + 45 °), and outputs the scan command angle θ in steps of 1 °. Numeral 8 denotes an offset circuit, which is provided with θ + θ · (β / 45) and θ−θ · (β
/ 45) is calculated and supplied as read command angles to the phase ROMs 1 and 1 ', respectively. In the present embodiment, the offset angle β is set to 1.3 °. Therefore, the read command angles supplied to the phase ROMs 1 and 1 ′ with respect to the scan command angle θ are as shown in the following table.

[0031]

[Table 1] θ θ + θ · (β / 45) θ−θ · (β / 45) -45 -46.3 -43.7 -44 -45.3 -42.7:::: -1 -1.03 -0.97 00 1 1.03 0.97:: : 44 45.3 42.7 45 46.3 43.7

Accordingly, in the phase ROM 1 for reading out a signal of 100 kHz, -46.3 ° -45.3 °.
° 0 ° 1.03 °... 45.3 ° Data for forming a transmission beam in 91 directions of 46.3 ° is stored in each phase ROM 1. In the phase ROM 1 'for reading a signal of 90 kHz, -43.7 ° -42.7 °
... -0.97 ° 0 ° 0.97 ° ... 42.7 ° Data for forming transmission beams in 91 directions of 43.7 ° is stored in each phase ROM 1 '.

In this way, the phase RO with respect to the original command angle θ
From M1, a scan angle offset to “+” is read, and the offset angle is proportional to θ, θ = −45 °,
At 45 °, the offset angle reaches a maximum of + 1.3 °. On the other hand, a scan angle offset to “−” is read from the phase ROM 1 ′, and the offset angle is also proportional to θ.
= −45 °, 45 °, the offset angle is −1.3 °.

Numeral 9 denotes an octal counter for counting the clock output from the clock pulse generator 10 from 0 to 17, and the count value is supplied to each phase R through the switch 11.
It is supplied to OM1 as a data read address. Therefore, the clock pulse generator 10 operates at 100 kHz (F _H ).
A clock is output at a speed of × 18. Reference numeral 12 denotes an 18-digit counter for counting the clock output from the clock pulse generator 13 from 0 to 17, and the count value is also supplied to each phase ROM 1 'through the switch 11 as a data read address. Therefore, the clock pulse generator 13 outputs a clock at a speed of 90 kHz (F _L ) × 18. These counters 9 and 12 are reset at the beginning of the trigger pulse output from the distance counter 5. Reference numeral 14 denotes a pulse generator. When the trigger pulse is input, the switching unit 11 has a transmission pulse width.
Turn on.

FIG. 10 shows a wave receiving unit for the wave transmitting unit of FIG. R is the wave receiver shown in FIG. 1 and is mounted near the wave transmitter S and the longitudinal direction thereof is set to the traveling direction of the measuring ship. Reference numeral 21 denotes an amplifier that amplifies a signal received by the receiver R, and reference numeral 22 denotes an A / D converter that converts the signal amplified by the amplifier 21 from analog to digital. 23 is A / D
This is an image memory for storing digital signals from the converter 22, and has a memory having a capacity of the number of pixels (P × Q) × I (number of bits) of the CRT 25 described later. Reference numeral 24 denotes a D / A converter for converting a digital signal read from the image memory 23 into an analog signal, and the CRT 25 includes a D / A converter 24.
The image of the signal is displayed.

Reference numeral 26 denotes a coordinate conversion circuit which converts the distance r and the azimuth θ obtained from the distance counter 5 and the azimuth counter 6 in FIG. 9 into rectangular coordinate data of x and y. Reference numeral 27 denotes a clock pulse generator which outputs a clock pulse having a cycle equal to the display period of one pixel on the CRT 25 to the X counter 28. The X counter 28 is a P (horizontal pixel count) counter for counting the clock pulse from 0 to P-1, and outputs a pulse to the Y counter 29 every time the count value returns from P-1 to 0. I do. This counter 29 sets the pulse output from the X counter 28 to 0.
This is a Q (vertical pixel number of CRT) base counter that counts up to Q-1.

Reference numeral 30 denotes a switch which switches in response to the "H" and "L" periods of the clock pulse from the clock pulse generator 27. For example, in the "H" period of the clock pulse,
The coordinate value (x, y) from the coordinate conversion circuit 26 is supplied to the image memory 23 as a write address, and during the “L” period of the clock pulse, the respective count values Cx from the X counter 28 and the Y counter 29 are output. , Cy are supplied as read addresses. Also, the clock pulse is
It is supplied to the image memory 24 as a read / write signal.

The operation of the above-described geological survey device will be described below. When the scan command angle θ from the azimuth counter 6 is 0 °, the read command angles supplied to the phase ROMs 1 and 1 ′ from the offset circuit 8 are both 0 °, and the beam characteristics of the transmission signal obtained at this time are shown in FIG. The result is the same as that shown in FIG.

On the other hand, when the scan command angle θ from the direction counter 6 is, for example, 45 °, the phase R
As shown in Table 1, the read command angles supplied to OM1 and OM 'are 46.3 ° and 43.7 °. Therefore, from the ultrasonic transmitters A _{1 to} A ₁₆ , 100 kHz is set in the direction of 46.3 °.
FIG. 13 shows a beam characteristic diagram at this time.
Is shown in Also, from the ultrasonic transmitters B _{1 to} B ₁₆ , 43.
An ultrasonic wave of 90 kHz is transmitted in the direction of 7 °, and a beam characteristic diagram at this time is shown in FIG.

FIG. 15 shows a beam characteristic diagram of the transmission signal of the secondary frequency (10 kHz) at this time. The main lobe M occurs in the same 45 ° direction as the scan command angle θ. Compared to FIG. 8, which is a beam characteristic diagram of the secondary frequency when scanning is performed in the 45 ° direction without offset, the beam width of the main lobe M becomes slightly narrower (therefore, the beam width becomes almost the same as that in the direction directly below). ),And,
It can be seen that the generation level of the side lobe S is suppressed.

Thus, with respect to the scan command angle θ,
The phase is shifted to the + side for a signal of 100 kHz (F _H ), and the phase is shifted to − for a signal of 90 kHz (F _L ).
By shifting to the side, the spread of the beam width of the main lobe can be suppressed, and the generation of the side lobe can also be suppressed.

As described above, when scanning is performed in the lateral direction, the beam width of the main lobe is widened, and the generation level of the side lobe is increased, and the degree is almost proportional to the scan angle. Therefore, as in the present embodiment, since the angle to be offset by the offset circuit 8 is made proportional to the scan command angle θ, the beam width of the main lobe can be made constant in all azimuth directions, and the generation of side lobes is uniform. Can be suppressed.

The beam width of the main lobe can be further narrowed by increasing the offset angle β. However, if the beam width is extremely narrow, the required transmission power cannot be obtained and the search cannot be performed. Therefore, the beam width of the main lobe when scanning laterally is almost equal to the beam width of the main lobe when transmitting directly below.
In the present embodiment, the offset angle β is set to 1.3 °. However, since this value changes depending on the mechanical structure (array of the vibrating elements, etc.) of the ultrasonic transmitter S, it may be appropriately selected according to each situation. Good.

FIG. 16 shows another embodiment of the present invention. In FIG. 9, the azimuth counter 6 supplies the scan read angle offset to the phase ROM 1 and 1 ′ by the offset circuit 8 with respect to the scan command angle θ, but the scan command angle θ of 45 ° is supplied to the phase ROM 1. At this time, if data for forming a beam in the direction of 46.3 ° from each phase ROM 1 is stored, the offset circuit 8 is unnecessary as shown in FIG.

Instead of changing the angle to be offset linearly in accordance with the scan angle, the offset may be divided into scan ranges, and an offset angle that changes stepwise for each section may be set. Further, the angle to be offset may be a fixed value. For example, scan command angle θ-45 -44…
-1 0 1 ... 44 45, the 100 kHz signal is shifted by 1.3 ° in each + direction, and 90 k
The signal of Hz may be shifted by 1.3 ° each. However, when the scanning direction is just below and the scan angle is small, the spread of the main lobe and the occurrence of the side lobe are small.
No offset in the range of + 10 °, -45 ° to -10
And may be offset in the range of 10 ° to 45 °.

[0046]

As described above, according to the present invention, the frequency f ₁ than this lower frequency f ₂ to transmit ultrasound at the same time, thereby resulting secondary frequency (f ₁ -f ₂₎ In a stratum explorer that conducts a stratum search based on echoes of an ultrasonic signal, when beam scanning is performed in the θ direction, the scan azimuth of the ultrasonic wave having the frequency f ₁ is shifted from θ to a positive value by β, and the ultrasonic wave having the frequency f ₂ is scanned. Since the azimuth was shifted negatively from θ by β and transmitted simultaneously, the beam characteristics of the secondary frequency obtained at this time are narrowed to the same extent as when the beam width of the main lobe is transmitted directly below. However, the detection resolution does not decrease. In addition, since the occurrence of side lobes is suppressed, the image is prevented from being unclear.

[Brief description of the drawings]

FIG. 1 is a plan view and a side view of a parametric ultrasonic transducer.

FIG. 2 is a diagram showing a transmitted and received beam when the parametric ultrasonic transducer of FIG. 1 is used.

FIG. 3 shows a diagram of the parametric ultrasonic transmitter shown in FIG.
Beam characteristic diagram when a 100 kHz ultrasonic wave is transmitted directly below

FIG. 4 shows a diagram of the parametric ultrasonic transmitter shown in FIG.
Beam characteristic diagram when a 90 kHz ultrasonic wave is transmitted directly below

FIG. 5 shows the parametric ultrasonic transmitter of FIG.
Beam characteristic diagram at the secondary frequency obtained when 100 kHz and 90 kHz ultrasonic waves are simultaneously transmitted in the direct downward direction

FIG. 6 shows a diagram of the parametric ultrasonic transmitter shown in FIG.
Beam characteristic diagram when an ultrasonic wave of 100 kHz is transmitted in the direction of 45 °

FIG. 7 shows an example of the parametric ultrasonic transmitter shown in FIG.
Beam characteristic diagram when a 90 kHz ultrasonic wave is transmitted in the 45 ° direction

FIG. 8 shows a diagram of the parametric ultrasonic transmitter of FIG.
Beam characteristic diagram at the secondary frequency obtained when simultaneously transmitting 100 kHz and 90 kHz ultrasonic waves in the 45 ° direction

FIG. 9 is a control block diagram of a wave transmitting section showing an embodiment of a geological survey device of the present invention.

FIG. 10 is a control block diagram of a wave receiving unit showing an embodiment of a geological survey device of the present invention.

FIG. 11 is a diagram showing a signal obtained by reading data stored in each phase ROM of FIG. 9;

FIG. 12 is a diagram showing signals obtained by reading data stored in each phase ROM of FIG. 9;

13 is a beam characteristic diagram when an ultrasonic wave of 100 kHz is transmitted in the direction of 46.3 ° by the parametric ultrasonic wave transmitter of FIG.

FIG. 14 is a beam characteristic diagram when a 90 kHz ultrasonic wave is transmitted in the direction of 43.7 ° by the parametric ultrasonic transmitter of FIG. 1;

FIG. 15 is a diagram illustrating a parametric ultrasonic transmitter shown in FIG.
Beam characteristic diagram at the secondary frequency obtained when the ultrasonic waves of kHz are simultaneously transmitted in the directions of 43.7 ° respectively.

FIG. 16 is a control block diagram of a transmission unit showing an embodiment of a geological survey device of the present invention.

[Explanation of symbols]

 Reference Signs List 1 phase ROM 2 amplifier 3 clock pulse generator 4 frequency divider 5 distance counter 6 azimuth counter 8 offset circuit 9 counter 10 clock pulse generator 11 switch 12 counter 13 clock pulse generator 21 amplifier 22 A / D converter 23 image Memory 24 D / A converter 25 CRT 26 Coordinate conversion circuit 27 Clock pulse generator 28 X counter 29 Y counter 30 Switching device S Ultrasonic wave transmitter R Receiver

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04R 17/00 330 G01S 7/52 D

Claims (8)

[Claims] 1. An ultrasonic wave having a frequency f ₁ and an ultrasonic wave having a frequency f ₂ lower than the frequency f ₁ are simultaneously transmitted, and a secondary frequency obtained thereby is obtained.
In a stratum exploration apparatus for stratum exploration based on an echo of an ultrasonic signal of (f ₁ −f ₂ ), a phase of an ultrasonic wave transmitted by each transducer of a transmitter is controlled in order to perform beam scanning in an arbitrary direction. Means for beam scanning in the θ direction by means of the frequency f ₁
Scan ultrasound scanning direction and (θ + β), the ultrasonic scanning direction of the frequency f ₂ and (θ-β), the said means, when the beam scanning in the -θ direction, the ultrasonic frequency f ₁ An underground exploration apparatus characterized in that the azimuth is (-θ-β), the scan azimuth of the ultrasonic wave of frequency f ₂ is (−θ + β), and the beam width of the main lobe is narrowed. Wherein frequencies f ₁ and which simultaneously transmitting ultrasonic waves lower frequency f ₂ than, thereby 2 obtained order frequency
In a stratum exploration apparatus for stratum exploration based on an echo of an ultrasonic signal of (f ₁ −f ₂ ), a phase of an ultrasonic wave transmitted by each transducer of a transmitter is controlled in order to perform beam scanning in an arbitrary direction. Means for beam scanning in the θ direction by means of the frequency f ₁
Scan ultrasound scanning direction and (θ + β), the ultrasonic scanning direction of the frequency f ₂ and (θ-β), the said means, when the beam scanning in the -θ direction, the ultrasonic frequency f ₁ An underground exploration apparatus characterized in that the azimuth is (-θ-β), the scan azimuth of the ultrasonic wave at the frequency f ₂ is (−θ + β), and the generation level of the side lobe is suppressed. 3. A frequency f ₁ and which simultaneously transmitting ultrasonic waves lower frequency f ₂ than, thereby 2 obtained order frequency
In a stratum exploration apparatus for stratum exploration based on an echo of an ultrasonic signal of (f ₁ −f ₂ ), a phase of an ultrasonic wave transmitted by each transducer of a transmitter is controlled in order to perform beam scanning in an arbitrary direction. Means for beam scanning in the θ direction by means of the frequency f ₁
Scan ultrasound scanning direction and (θ + β), the ultrasonic scanning direction of the frequency f ₂ and (θ-β), the said means, when the beam scanning in the -θ direction, the ultrasonic frequency f ₁ An underground survey in which the azimuth is (-θ-β), the scan azimuth of the ultrasonic wave of frequency f ₂ is (-θ + β), the beam width of the main lobe is narrowed, and the generation level of the side lobe is suppressed. apparatus. 4. An ultrasonic transmitter (S) including a first ultrasonic vibrator group (A) and a second ultrasonic vibrator group (B), and each ultrasonic vibrator group ( a, B) in order to form a transmission beam to individually desired orientation, each group of ultrasound transducers (a), (B) a low frequency f ₂ of the ultrasonic signal is also frequency f ₁ supplied respectively thereby And phase ROMs (1) and (1 ′) storing sampling data for each direction.
Ultrasonic transducer group (A) and second ultrasonic transducer group (B)
, The ultrasonic waves of the frequency f ₁ and the frequency f ₂ are simultaneously transmitted in the direction of the desired scan command angle θ, and the echo of the ultrasonic signal of the secondary frequency (f ₁ −f ₂ ) obtained by this A stratum exploration apparatus for striking a stratum by receiving waves with a receiver (R), wherein a phase ROM (1)
Now read the data in the (θ + β) direction,
In (1 ′), data in the (θ−β) direction is read, and for the scan command angle −θ, data in the (−θ−β) direction is read in the phase ROM (1), and in the phase ROM (1 ′). (−θ +
Be sure to read each phase ROM
(1), (1 ′), a geological survey device characterized by storing corresponding data. 5. The underground exploration apparatus according to claim 4, wherein the value of β is proportional to the scan command angle θ. 6. The geological survey device according to claim 4, wherein the value of β is a fixed value. 7. The geological exploration apparatus according to claim 4, wherein when the scan command angle θ is equal to or smaller than a predetermined angle, the scan command angle is equal to the scan azimuth, and when the scan command angle θ is equal to or larger than the predetermined angle, the scan azimuth is shifted based on β. 8. A transmitting ultrasonic waves of frequency f ₁ than this lower frequency f ₂ at the same time, thereby secondary frequency obtained
A beam scanning method for obtaining an ultrasonic signal of (f ₁ −f ₂ ), comprising means for controlling a phase of an ultrasonic wave transmitted by each transducer of a transmitter to perform beam scanning in an arbitrary direction. When beam scanning is performed in the θ direction by the means, the frequency f ₁
Scan ultrasound scanning direction and (θ + β), the ultrasonic scanning direction of the frequency f ₂ and (θ-β), the said means, when the beam scanning in the -θ direction, the ultrasonic frequency f ₁ A beam scanning method, wherein the azimuth is (-θ-β), the scan azimuth of the ultrasonic wave of frequency f ₂ is (-θ + β), and the beam width of the main lobe is narrowed.