JPH02244899

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DESCRIPTION JPH02244899
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for
example, a method of receiving an acoustic signal in water, and more particularly to a method of
forming directivity of a receiver for forming a sharp directivity in a predetermined direction.
[Prior Art] FIG. 2 is a block diagram of a conventional receiver acoustic wave signal detecting
apparatus as disclosed in, for example, Japanese Patent Application No. 63-76277, in which l-1
and 1-2 are respectively nondirectional. It is a receiver of an acoustic signal such as a
hydrophone or a microphone having a directivity characteristic of sex, and is disposed at a half
interval of the natural wavelength of the acoustic signal in the incident direction of the W echo
signal. 3-1 and 3-2 are amplifiers having the same signal amplification factor, 4-1 and 4-2 are P
wave devices (for example, band pass filters) having the same band pass characteristics, and 5-i%
5-2 is a detection circuit , 6 is a dividing circuit, 7 is an adding circuit, and 8 is a subtracting
circuit. The operation of FIG. 2 will be described. Acoustic signals input from the target sound
source are received by the receivers 1- and 1-2, converted into electrical signals, and input to the
amplifiers 3-1 and 3-2, respectively. The amplifiers 3-1 and 3-2 amplify the human power signal
with the same signal amplification factor, and supply the output signal to the P wave devices (for
example, band pass filters) 4-1 and 4-2. The P wavers 4-1 and 4-2 pass only a constant band
frequency which is the BNN station frequency center circumference limb number of the target
sound cause a and attenuates the other frequencies. A pair of signals r-waved by the P wave
devices 4-1 and 4-2 are input to the adding circuit 7 and the subtracting circuit 8, respectively.
The adder circuit 7 calculates the sum signal Σ of the two signals input, and the subtractor
circuit 8 calculates the difference signal Δ of the two signals and inputs them to the detector
circuits 5-1 and 5-2. The tA wave circuits 5-1 and 5-2 detect the input sum signal Σ and
difference signal Δ, and input the detection output signals 及 び 1 and Δ to the division circuit
6, respectively. The division circuit 6 divides the input difference detection signal Δ as a
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dividend and the sum detection signal 、 as a divisor, and outputs a division output signal, that is,
Δ, / Σ, as a detection signal. FIG. 3 is an output characteristic diagram when the acoustic
incident angle of the wave receiver of FIG. 2 is 0 degree. In the figure, with respect to the base IfI
axis lJ with the alignment direction of the nondirectional receivers 1-1 and 1-2 arranged at an
interval of λ / '2 of half the wavelength λ of the human-powered acoustic signal as a reference
axis When the acoustic signal of wavelength λ is manually operated from the direction of the
incident angle θ-0 ′ ′ (the direction of the reference axis) and the output signal E1 of the
receiver 1-1 is a negative maximum value, The output signal E2 has a positive maximum value
4L. Therefore, the output signal E of the wave receiver 1-1 and 1-2.
The absolute value IΣ1 of the sum of and E2 is expressed by the following equation (1). 絶 対
1−IE + E 1−0 1) Further, the absolute value 1Δ1 of the difference between the output signals
E1 and E2 is expressed by equation (2). Δ 1 -IE + E 21-12 E 2 1 (2) FIG. 4 is a directivity
characteristic diagram of the sum signal 1 1 1 and the difference a 1 Δ 1 of the device of FIG. In
the figure, the sum signal 1 1 1 is zero at the incident angle θ-01 'and increases as the incident
angle θ increases in the positive or negative direction. Further, the difference signal 1Δ1 is
maximum at the incident angle θ-o ′ ′, and decreases as the incident angle θ increases in the
positive or negative direction], and becomes zero at θ- ± 90 °. FIG. 5 is a directivity
characteristic diagram of detection signals of the apparatus of FIG. 2, and it can be seen that the
maximum output and sharp directivity are formed in the direction in which the acoustic incident
angle θ is 0 degree. Also, the directional characteristic diagram in the same figure is a twodimensional display, but actually it shows a three-dimensional spatial characteristic diagram
obtained when rotating in all directions (360 ') with the incident angle θ-〇a as a reference axis.
is there. ? J6 is a diagram showing an operation example of the apparatus of FIG. 2, in which 10
^ is a receiver of nondirectional characteristics I and 1-2 in the vertical direction and 172 of the
specific wavelength of the target sound source. Acoustic sensors 11 arranged at intervals, 11 is a
measuring vessel, 12 is a cable connecting the acoustic sensor 10A to the device in the
measuring vessel 13, 13 is a float, 14 is a sinker installed on the seabed, 15 is It is a sound
source. In the acoustic sensor unit lO, a lobe from the sinker 14 installed on the seabed is
attached to one end, and a rope from the float 13 is attached to the other end. Will be installed.
An output signal from the acoustic sensor unit 10A is connected to an internal circuit of the
measuring vessel 11 by a cable 12 to measure a moving sound source. [Problems to be Solved by
the Invention] In the conventional receiver directivity forming apparatus as described above,
there are three types of subtraction circuits that calculate difference signals, addition circuits that
calculate sum signals, and division circuits that calculate ratio signals. In order to require an
arithmetic circuit, there is a problem that the arithmetic circuit is complicated and the apparatus
becomes expensive. Also, as shown in the operation example of FIG. 6, although the acoustic
sensor unit is installed vertically toward the seabed, actual input waves are not only direct waves
from above, but also from below the sinker, seabed, etc. Because reflected waves are also present,
the directivity characteristics of FIG. 5 are affected by disturbances and the like. In order to avoid
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the adverse effect on the directivity characteristic, there is no other suitable method than moving
the acoustic sensor unit away from the surrounding reflective objects, and the installation
location is limited.
The present invention has been made to solve such problems, and it eliminates the influence of
reflected waves from the bottom of the seabed or the like on directivity characteristics, and
achieves desired directivity characteristics with a simple and inexpensive arithmetic circuit. An
object of the present invention is to provide a method for forming a receiver directivity
characteristic. [Means for Solving the Problems] In the receiver directivity forming method
according to the present invention, a baffle plate made of a material having a smaller value of
acoustic impedance compared to water, and a direction perpendicular to the baffle plate A first
receiver having non-directional characteristics disposed at a distance of 1/2 of the characteristic
wavelength of the measured acoustic signal, and an object in the same direction as the first
receiver, perpendicular to the baffle plate. And a second receiver having non-directional
characteristics disposed at a distance of 1/4 or more of the characteristic wavelength of the
measurement acoustic signal, and an output signal based on the second receiver and the first
receiver. By calculating the ratio to the output signal based on the receiver to obtain the acoustic
detection signal, sharp directivity is engraved in the direction perpendicular to the baffle plate.
[Operation] In the present invention, first, as an acoustic sensor, a baffle plate made of a material
having a small value of acoustic impedance as compared to water; A first wave receiver having
omnidirectional characteristics disposed at a short distance of 1 node 2 of a wavelength, and a
wave meter constant acoustic signal perpendicular to the baffle plate and in the same direction
as the tenth wave receiver. And a second wave receiver having non-directional characteristics.
With the arrangement of such a pair of wave receiver and baffle plate, in the first wave receiver,
the direction of the incident angle of 0 degree (the perpendicular direction from the baffle plate
to the wave 1 g) is? If an acoustic signal is input /-if-directly from the incident wave and on the
other hand, from the baffle plate! The phases of the waves are opposite to each other, and both
waves are canceled out, resulting in the minimum output. Also, in the second wave receiver, the
angle of incidence of the radiation angle ) is the largest in the direction of dust, and the angle
of incidence ± 9 ol y (t two directions along the plane of the plate T / 7 / L) 、 Jj jj 比 比 比 比
比 比 比 比 比 比 比 比 外出 外出 外出 外出 外出 外出 外出 外出 外出 外出 外出 外出 外出 外出 外
出 外出 外出. To obtain an acoustic detection signal, the above-mentioned. . 7,) l / can form sharp
directivity in the direction perpendicular to the plate. FIG. 1 shows the reception IQf according to
the present invention! I) directional pattern device) ') block diagram, J-11-2, 3-1 to-) are 1-. The
same device as the conventional device is used.
2 is the use of water, more than 1 · 1 person sound a In Vieve f, ≠ 1, material R,: J: 戊 ・ ・ フ ル
(ffle plate, lO is an acoustic sensor section inside the wave receiver 1-1 and 1-2 and the baffle
plate 2 are accommodated. FIG. 7 is a structural view of an echo sensor unit according to the
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present invention, and 1-1.12 each have one nondirectional characteristic reception 2 and 2 each
have an acoustic impedance of water of about 1.about.1. . It is a baffle plate made of a material
whose acoustic impedance value is as small as I / 3 of water, for example, spock; ·, six corks, etc.
while it is 5 × 10 'kg · gec / rd. In this case, the receiver i-i has a wavelength λ corresponding to
the natural frequency f of the two target sound sources in a direction perpendicular to the bulk;
The wavelength λ is calculated from the relationship of / f. ), Ie, at a distance of λ / 2. Also, the
wave receiver 1-2 is such that the distance Mg between the baffle plate 2 and the baffle plate 2 is
O <9 <λ / 4 on the same axis as the perpendicular from the baffle plate 2 to the wave receiver I.
2 is set up. Further, the space between the wave receiver 1-1 and the wave receiver 1-2 and the
space between the wave receiver 1-2 and the baffle plate 20 are filled with a material whose
acoustic impedance value is substantially equal to that of water. The operation of FIG. 1 will be
described with reference to FIG. The acoustic signals input from the target sound source are
received by the receivers 1-1 and 12 and converted into electric signals, and the output signals
from the receivers 1-1 and 1-2 are amplified respectively 'a'; j3 The signals amplified by 1 and 32 are amplified, and the output signals from 1 amplifier and 1 and 2-2 each have only the
frequency of the required band by P wave device 4 '' At 1 and 4-2 respectively. The operation of
passing through and obtaining a pair of output signals is similar to that of the conventional
apparatus of FIG. However, in the present invention, the tube receiver: · · · The receiver 1-2 in the
part 10 is λ, '4! By providing a basin plate 2 at a distance under rJ, the directional
characteristics of a single-door unit, (-1 and 卜: T へ そ れ 庁 庁 庁 、, 14 1 1 If this is not the
case, then this 31 快 快 及 び 及 び 4− 4− and 4 は 2 output signal is one operation of addition
and subtraction, L: · y? (Alternatively, they can be directly supplied to the detection circuits 5-1
and 5-2, respectively. FIG. 8 is a diagram showing an example of measurement of directivity
characteristics of one sensor unit according to the present invention; FIG. 8 is an amplification
signal of an output signal obtained from the r ridge line it wave receiver 1, -1 shown in FIG. The
directivity characteristics after r, the solid line is the wave receiver 1. Out-obtained from -2!
"Amplification of the signal, P i! 12 rear J 指 finger]] t- 持 in Fig. 8 is vertical to the baffle plate 2
and the alignment direction of the receivers 1-1 and 1-2 is 0 degree of the reference azimuth,
The right side of the reference orientation is a positive angle, and the left side is a negative angle.
9 is an explanatory view for explaining the directivity characteristics of FIG. 8, FIG. 9 (a) is a
layout diagram of a receiver and a baffle plate, FIG. 9 (b) is a directivity characteristic diagram at
d−λ / 2, (C) is a directivity characteristic view when 0 <d <λ / 4. In FIG. 9 (a), it is assumed
that the baffle plate is a soft baffle and is an ideal perfect reflector. Further, it is assumed that a
true receiver is set at point A at a distance d in the vertical direction from the baffle plate, and a
sound wave is incident from a sound source in the direction of the incident angle θ from the
reference direction. In this case, the receiver of the tool receives the direct incident wave from
the sound source and the reflected wave whose phase is inverted reflected from the baffle plate,
and a composite signal of these two waves is obtained. In this phenomenon, an imaginary
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receiver is present at a point B symmetrical to the point A of the distance Md with the baffle plate
as a reference plane, and the output of this true receiver and the output signal of the imaginary
receiver Equivalent to obtaining a signal of the difference between Also, the directivity
characteristic function R of the difference signal between these two true and imaginary receivers
is given by the following equation (3). R-sin (2yrd / λ ′ ′ cos θ) − (3) where λ is the
wavelength of the sound wave, θ is the incident angle of the sound wave, and d is the distance
between the wave receiver and the baffle plate. When the distance d−λ / 2 is satisfied, the
above equation becomes the following equation (4). The directivity characteristic of this equation
(4) is as shown in FIG. 9 (b), and this characteristic approximates to the directivity shown by the
broken line in FIG. . The characteristic of the broken line in FIG. 8 is similar to the sum signal
1Σ1 in FIG. 4 of the conventional device. Therefore, the conventional addition circuit 7 is not
necessary. Further, when the distance d is 0 d / λ / 4, the directivity characteristic is as shown
in FIG. 9 (e), and this characteristic approximates the directivity characteristic shown by the solid
line in FIG. Since the actual baffle plate 2 is not a perfect reflector, some characteristic changes
occur in the broken and solid lines of FIG. The characteristic of the solid line in FIG. 8 is similar to
the difference signal 1Δ1 in FIG. 4 of the conventional device. Therefore, the conventional
subtraction circuit 8 is not necessary. In addition, even when the incident wave contains noise in
a band different from the signal frequency, these noises are removed by P wave devices 4-1 and
4-2, respectively, from the outputs of P wave devices 4-1 and 4-2, respectively. The directional
characteristics of the broken line and the solid line of FIG. 8 can be obtained. Further, the baffle
plate 2 also has a sound insulation effect of reflecting the interference noise coming from the
back direction, that is, the direction without the receiver and not transmitting it to the receiver
side. Therefore, even if there is a reflective object such as the seabed, the directivity
characteristic of FIG. 8 is not disturbed.
The output signals of the r wave devices 4-1 and 4-2 are detected by the detecting circuits 5-1
and 5-2, respectively, and supplied to the dividing circuit 6. The division circuit 6 divides the
output signal of the detection circuit 5-2 as a dividend, divides the output signal of the detection
circuit 5-1 as a divisor, and outputs the division result as a detection signal. FIG. 10 is a
directivity characteristic diagram of an acoustic detection signal according to the present
invention, and as shown in the drawing, the maximum output and sharp directivity
characteristics are formed in the direction of 0 degrees, ie, the direction perpendicular to the
baffle plate 2. In the above embodiment, the receivers 11 and 1-2 are provided on the same
perpendicular line with respect to the baffle plate 2. However, the present invention is not limited
to this. Device 1-2 is perpendicular to the baffle plate 2 and in the same direction as the wave
receiver 1-1, even if it is not necessarily on the same axis as the perpendicular line to the baffle
plate 2 of the wave receiver 1-1. You can get the effect of As described above in detail, according
to the present invention, a baffle plate made of a material whose acoustic impedance is smaller
than that of water, and a solid of a measured acoustic signal in a direction perpendicular to the
baffle plate. Providing first and second receivers having non-directional characteristics
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respectively disposed at a distance of 1/2 of the wavelength and a distance of 1/4 or less, and an
output signal based on the second receiver and the above Since the sharp directivity in the
direction perpendicular to the baffle plate is formed by calculating the ratio to the output signal
based on the first receiver and obtaining the acoustic detection signal, the back surface of the
baffle plate is obtained. That is, the influence of the reflected wave from the reverse direction to
the wave receiver with respect to the baffle plate is removed, the effect of improving the stability
of the directional characteristics, and the addition circuit and subtraction circuit conventionally
required become unnecessary, and the wave receiving device And the cost reduction effect of
[0002]
Brief description of the drawings
[0003]
1 is a block diagram of a receiver directivity forming apparatus according to the present
invention, FIG. 2 is a block diagram of a conventional receiver acoustic signal detecting
apparatus, and FIG. 3 is an acoustic incidence of the receiver of FIG. Output characteristics when
the angle is 0 degree, FIG. 4 shows directivity characteristics of the sum signal 1Σ1 and
difference signal 1Δ1 of the device of FIG. 2, FIG. 5 shows directivity characteristics of detection
signals of the device of FIG. 6 shows an operation example of the apparatus shown in FIG. 2, FIG.
7 shows a configuration of an acoustic sensor unit according to the present invention, and FIG. 8
shows a measurement example of directivity characteristics of the acoustic sensor unit according
to the present invention. FIGS. 9 (a), 9 (b) and (c) are explanatory views for explaining the
directivity characteristics of FIG. 8, and FIG. 10 is a directivity characteristic diagram of an
acoustic detection signal according to the present invention.
In the figure, 1-1, 1-2 are receivers, 2 is a pubful plate, 3-1, 3-2 are amplifiers, 4-1.4-2 are P
wavers, 5-1.5-2 are A detection circuit, 6 is a division circuit, 7 is an addition circuit, 8 is a
subtraction circuit, 10.10 ^ is an acoustic sensor unit, 11 is a measuring ship, 12 is a cable, 13 is
a float, 14 is a sinker, and 15 is a sound source. 1-1-"--Sand 2 received wave H graduate
invention 1; drawing of acoustic sentry part Fig. 7 宍 1 衷: wave receiver"-2 non-inventive r-tetsu
V 'Fig. 8 同 椙 椙 椙 装置 装置 椙 例 例 例 例 例 例 2 2 2 2 2 2 2 2 2 2 2 2 2 Figure 2 Figure
reference azimuth i wave startle 777 7 o 777-baffle plate Lα-B; imaginary received wave a
received wave win and arrangement of baffle plate 0c 'finger Cj temporary name explanatory
drawing of Fig 8 Figure 9
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