close

Вход

Забыли?

вход по аккаунту

?

JP2006208107

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2006208107
In a transducer including a cylindrical portion and a hemispherical portion, grating lobes in the
vertical direction are suppressed and directivity deviation is minimized by devising the
arrangement of transducers. In a cylindrical portion (1A), a vibrator (10a) is disposed such that
six vibrators adjacent to one vibrator are positioned at each vertex of a regular hexagon (8). It
arranges so that one set of sides 9 may turn to the perpendicular direction. In the hemispherical
portion 1B, when a figure obtained by projecting a regular pentagon that constitutes a regular
dodecahedron inscribed in the spherical surface of the hemispherical portion 1B onto the
spherical surface is a spherical pentagon 5, it constitutes a component of the spherical pentagon
5. The vibrator 10b is disposed at the vertex of the spherical triangle 6, the point obtained by
equally dividing each side of the spherical triangle 6, and the center of gravity of a small
spherical triangle formed by arcs connecting these equal division points. [Selected figure] Figure
6
Ultrasonic transducer and underwater detection device
[0001]
The present invention relates to an ultrasonic transducer and an underwater detection device
used to detect fish and the like in water.
[0002]
Conventionally, a scanning sonar has been used as an ultrasonic device for detecting underwater
information such as a school of fish over a wide area.
04-05-2019
1
The scanning sonar transmits an ultrasonic beam in a predetermined direction in the water and
receives an echo reflected from a target in the water (hereinafter, simply referred to as a
"transmitter"). ). As this transducer, there are various ones as shown in FIG.
[0003]
FIG. 10 shows a cylindrical transducer 50 used for a scanning sonar of a full scan type. The
transducer 50 has a large number of ultrasonic transducers 51 which are disposed
circumferentially and axially on the side of the cylinder. After transmitting an umbrella-shaped
ultrasonic beam at 360 ° from the ultrasonic transducers 51 at a predetermined tilt angle all at
once, the detection region is scanned all around to receive an echo. In the case of this transducer
50, detection of a wide range can be performed by electronically controlling the tilt angle, but
since the ultrasonic transducer 51 is provided only on the side surface of the transducer 50, it is
directly below the ship. There is a drawback that the direction can not be detected.
[0004]
FIG. 11 shows a semi-cylindrical transducer 60 used in a half-turn scanning scanning sonar. The
transducer 60 has a large number of vertically elongated ultrasonic transducers 61 disposed
circumferentially on the side surface of a partially cut half cylinder. After transmitting a fanshaped ultrasonic beam from the ultrasonic transducers 61 simultaneously to a half-turn (180
°) area, the detection area is scanned for half-turn to receive an echo. A bearing mechanism 62
rotates the transducer 60 in the horizontal direction to control the bearing angle of the ultrasonic
beam by rotating in the a direction by driving of a motor (not shown). A tilt mechanism 63
rotates the transducer 60 in the vertical direction by controlling the tilt angle of the ultrasonic
beam by rotating the transducer 60 in the b direction by driving the motor (not shown). In the
case of this transducer 60, although the detection of a wide range including the direction directly
under the ship can be performed by mechanically controlling the bearing angle and the tilt angle,
the ultrasonic transducer 61 is divided in the vertical direction. However, the beam width and
sublevel can not be adjusted by weight control in the direction orthogonal to the scan plane.
[0005]
04-05-2019
2
If both of the transducer 50 for the full scan in FIG. 10 and the transducer 60 for the half scan in
FIG. 11 are mounted on the hull, it is possible to solve the above-mentioned problems. The
installation of the transducer is problematic in terms of cost and installation space, and is difficult
to install, especially on small vessels. Therefore, recently, a spherical transducer having both
functions of full scan and half scan has been developed, and a scanning sonar using this has been
put to practical use. The spherical transducer is described, for example, in Patent Document 1
and Patent Document 2 listed below.
[0006]
FIG. 12 shows the spherical transducer 70 described above. The transducer 70 has a large
number of ultrasonic transducers 71 divided and arranged on the surface of the sphere, and after
transmitting ultrasonic beams from these transducers 71 in a predetermined direction, the
detection region is scanned And receive an echo. In the case of this transducer 70, since the
ultrasonic transducers 71 are provided at the side and bottom of the sphere, a single transducer
can detect a wide range including the direction directly below the ship, and weight control is also
possible. . However, as in the case of a cylindrical transducer (FIG. 10), the transducers are not
arranged in a straight line in the vertical direction, and the direction of the beam emission plane
of the transducer 71 is horizontal as going to the top and bottom of the sphere. As a result, the
intensity of the horizontal beam is weakened and the horizontal detection distance can not be
increased, and the resolution in the vertical direction is also degraded.
[0007]
Therefore, as means for solving these problems, it is conceivable to configure the transducer
from a cylindrical portion and a hemispherical portion. Patent Document 1 mentions a
transducer whose upper part is a cylindrical part and whose lower part is a hemispherical part
(see paragraph 0040). If such a transducer is used, the detection distance and the vertical
direction in the horizontal direction can be made vertical by taking advantage of the cylindrical
transducer 50 shown in FIG. 10 and the spherical transducer 70 shown in FIG. A wide range of
detections, including directly below the ship, can be performed with a single transducer without
sacrificing directional resolution.
[0008]
Patent documents 1: Unexamined-Japanese-Patent No. 2001-343450 (paragraph number 00150017, FIG. 1) Unexamined-Japanese-Patent No. 2000-162308 (paragraph number 0029-0053,
04-05-2019
3
FIG. 1-5)
[0009]
In the case of manufacturing a transducer including a cylindrical portion and a hemispherical
portion as described above, it is necessary to devise an arrangement of transducers in each of the
cylindrical portion and the hemispherical portion.
For example, in order to suppress grating lobes generated in the vertical direction during
horizontal scanning, it is necessary to minimize the pitch of the ultrasonic transducer in the
vertical direction, and to minimize the directivity deviation of the ultrasonic beam. In order to
achieve this, it is necessary to provide continuity in the arrangement of transducers in the
cylindrical portion and the hemispherical portion. Patent Document 1 makes no mention of such
an array of transducers. On the other hand, in Patent Document 2, vibrators are arranged at the
apex of a regular polyhedron inscribed in a spherical surface, and vibration is performed at an
interval position regarded as substantially equal intervals with respect to each vibrator arranged
at this apex. By placing the child, it is described that transducers are arranged uniformly and
precisely in the detection range, and all directions under the water surface are detected precisely
and at high speed, but the transducer of this document is spherical There is no mention at all of
the arrangement of the transducers in the cylindrical part and the continuity of the transducer
arrangement in the cylindrical part and the hemispherical part. For this reason, the problem is
how to arrange the transducers in the cylindrical portion and the hemispherical portion to
minimize the grating lobe and the directivity deviation.
[0010]
An object of the present invention is to provide a transducer in which grating lobes in the vertical
direction are suppressed by devising the transducer arrangement of the transducer consisting of
a cylindrical portion and a hemispherical portion. Another object of the present invention is to
provide a transducer in which directivity deviation is minimized by providing continuity in the
arrangement of transducers in the cylindrical portion and the hemispherical portion.
[0011]
The transmitter-receiver according to the present invention is an ultrasonic transmitter-receiver
having an upper cylindrical portion and a lower hemispherical portion connected to the lower
04-05-2019
4
cylindrical portion, and an ultrasonic transducer provided in each of the cylindrical portion and
the hemispherical portion. The ultrasonic transducer in the cylindrical part is positioned so that
the six ultrasonic transducers adjacent to one ultrasonic transducer are located at each vertex of
the regular hexagon, It arrange | positions so that the edge | side of a group may become parallel
to the axial direction of a cylindrical part.
[0012]
By arranging the ultrasonic transducers in the cylindrical portion in this manner, the pitch in the
vertical direction of the transducers can be minimized, so that grating lobes generated in the
vertical direction at the time of horizontal scanning can be suppressed.
In addition, since the surface of a cylindrical part is a curved surface and can not arrange |
position a regular hexagon exactly, a regular hexagon said above means the regular hexagon in
the plane at the time of expand | deploying a cylinder.
[0013]
Further, in the transducer according to the present invention, when a figure obtained by
projecting a regular polygon that constitutes a regular polyhedron inscribed in the spherical
surface of the hemispherical portion onto the spherical surface is a spherical polygon, ultrasonic
vibration of the hemispherical portion The vertex of a spherical triangle forming a component of
a spherical polygon, a point obtained by equally dividing each side of the spherical triangle, and
the center of gravity of a small spherical triangle formed by an arc connecting these equal
division points Place each on.
[0014]
By arranging the ultrasonic transducers in the hemispherical part in this way, it is possible to
arrange the ultrasonic transducers on the spherical surface of the hemispherical part
substantially at regular intervals, and to make the ultrasonic transducers continuous from the
cylindrical part to the hemispherical part It is possible to arrange it.
For this reason, it is possible to minimize the directivity deviation due to the discontinuity of the
arrangement of the transducers near the boundary between the cylindrical portion and the
04-05-2019
5
hemispherical portion.
[0015]
In a preferred embodiment of the present invention, the regular polyhedron inscribed in the
spherical surface of the hemispherical portion is a regular dodecahedron, and the spherical
polygon is arranged with one face of the regular dodecahedron facing vertically downward. And
a spherical pentagon obtained by projecting a regular pentagon constituting the regular
dodecahedron onto a spherical surface. By using a regular dodecahedron as a regular
polyhedron, it is possible to easily design to minimize the pitch in the vertical direction of the
transducers in the cylindrical part while maintaining the continuity of the transducer
arrangement between the cylindrical part and the hemispherical part.
[0016]
Next, the underwater detection device according to the present invention has a plurality of
ultrasonic transducers, transmits ultrasonic beams from the ultrasonic transducers in a
predetermined direction in water, and echoes echoes reflected by targets in water. Based on an
ultrasonic transducer received by an ultrasonic transducer, transmission control means for
outputting a transmission signal for driving an ultrasonic transducer to transmit an ultrasonic
beam, and echoes received by the ultrasonic transducer An underwater detection device
comprising: reception control means for processing reception signals to obtain underwater
information; and display means for displaying the underwater information obtained by the
reception control means, wherein the ultrasonic transducer has the above-mentioned vibration. It
consists of a transducer with a child arrangement. The ultrasonic transducer transmits an
umbrella-shaped ultrasonic beam in all directions in the water to perform a full scan, and
transmits a fan-shaped ultrasonic beam in a half-round region of the water to perform a halfround scan. .
[0017]
Since this underwater detection device uses a transducer consisting of a cylindrical portion and a
hemispherical portion, taking advantage of the advantages of the cylindrical transducer and the
spherical transducer, the horizontal detection distance and the vertical direction can be obtained.
A wide range of detections, including directly below the ship, can be performed with a single
04-05-2019
6
transducer, without sacrificing resolution. Further, by arranging the ultrasonic transducers of the
cylindrical portion as described above, it is possible to minimize the pitch in the vertical direction
of the transducers and to suppress grating lobes generated in the vertical direction at the time of
horizontal scanning. Furthermore, by arranging the ultrasonic transducers in the hemispherical
portion as described above, the alignment of the transducers in the cylindrical portion and the
hemispherical portion can be made continuous, and the directivity deviation can be minimized.
[0018]
In the underwater detection device of the present invention, in the cylindrical portion of the
ultrasonic transducer, since the horizontal pitch of the transducers becomes larger than the
vertical pitch, there is a grating lobe generated in the horizontal direction during horizontal
scanning. Although this is a problem, for example, the influence of grating lobes in the horizontal
direction can be reduced by adopting a method of performing transmission and reception using
signals of different frequencies depending on the azimuth. In this case, the transmission control
means of the underwater detection device drives the ultrasonic transducer so as to transmit
ultrasonic beams of different frequency bands according to the azimuth, and the reception
control means selects the frequency according to the azimuth and receives the predetermined
azimuth Get a signal.
[0019]
Further, in the underwater detection device according to the present invention, the signal
frequency is made different between when performing the full scan and when performing the
half scan, so that the full scan and the half scan can be simultaneously performed by one
transmission / reception. Good. In this case, the transmission control means of the underwater
detection device generates transmission signals of different frequencies f1 and f2, and when
performing a full scan, the ultrasonic transducer is driven by the transmission signal of the
frequency f1 to perform a half scan When this is done, the ultrasonic transducer is driven by the
transmission signal of frequency f2. Further, the reception control means extracts frequency
components corresponding to the different frequencies f1 and f2 as a reception signal.
[0020]
According to the present invention, a single transducer can perform a wide range of detection
04-05-2019
7
including the direction directly below the ship without sacrificing the horizontal detection
distance and the vertical resolution, while reducing cost and saving space. Can be installed on
small vessels. Further, by devising the arrangement of the transducers in the cylindrical portion,
it is possible to minimize the pitch in the vertical direction of the transducers and to suppress
grating lobes generated in the vertical direction at the time of horizontal scanning. Furthermore,
by devising the arrangement of transducers in the hemispherical part, continuity can be given to
the arrangement of transducers in the cylindrical part and the hemispherical part, and the
directivity deviation can be minimized.
[0021]
FIG. 1 is a front external view showing an embodiment of a transducer according to the present
invention. The transducer 1 comprises an upper cylindrical portion 1A and a lower hemispherical
portion 1B continuous with the cylindrical portion 1A. K is a cable for transmitting and receiving
signals. The cylindrical portion 1A has a large number of ultrasonic transducers 10a arranged
according to the arrangement method described later, and the hemispherical portion 1B also has
a large number of ultrasonic transducers 10b arranged according to the arrangement method
described later There is. Each of the ultrasonic transducers 10a and 10b is composed of a
transducer having a circular ultrasonic radiation surface.
[0022]
FIG. 2 is a view for explaining an arrangement method of the ultrasonic transducers 10a in the
cylindrical portion 1A. Assuming that FIG. 2 is a flat surface developed from the cylindrical
portion 1A, each ultrasonic transducer 10a is arranged such that six transducers adjacent to one
transducer are located at each vertex of the regular hexagon 8 respectively. It is done. The pair of
opposite sides 9 of the regular hexagon 8 is disposed parallel to the axial direction Y of the
cylindrical portion 1A, that is, oriented in the vertical direction. α is the pitch in the vertical
direction (Y direction) of the vibrator 10a, and β is the pitch in the horizontal direction (X
direction) of the vibrator 10a. α and β have a relationship of α <β. These pitches α and β are
both set to dimensions shorter than the wavelength of the ultrasonic wave in order to suppress
grating lobes generated in the direction of 90 ° with respect to the main lobes. When the
ultrasonic transducers 10a are arranged in the cylindrical portion 1A according to the
arrangement algorithm as described above, the pitch α in the vertical direction of the
transducers 10a is minimized, and the vibrators 10a are closely spaced on the surface of the
cylindrical portion 1A. Can be arranged.
04-05-2019
8
[0023]
FIGS. 3-5 is a figure explaining the arrangement method of the ultrasonic transducer | vibrator
10b in hemispherical part 1B. In FIG. 3, 2 is a spherical surface in the case where two
hemispherical portions 1B are combined, 3 is a regular dodecahedron inscribed in the spherical
surface 2, and 4 is a regular pentagon constituting each surface of the regular dodecahedron 3.
In addition, this FIG. 3 is the figure which looked at the regular dodecahedron 3 from directly
above in the state arrange | positioned so that one surface of the regular dodecahedron 3 may
face vertically downward (direction orthogonal to a paper surface). Reference numeral 5 denotes
a spherical pentagon obtained by projecting the regular pentagon 4 constituting the regular
dodecahedron 3 onto the spherical surface 2. In the hemispherical portion 1 B, the ultrasonic
transducers 10 b are arrayed using the spherical pentagon 5. The arrangement algorithm will be
described below.
[0024]
As shown in FIG. 4A, assuming that the apex of the spherical pentagon 5 is A to E and the center
of gravity is F, the spherical pentagon 5 is a five spherical triangle 6 (ΔFAB, It can be divided
into ΔFBC, ΔFCD, ΔFDE, ΔFEA). These spherical triangles are exactly spherical isosceles
triangles. It is needless to say that since the spherical pentagon 5 and the spherical triangle 6 are
figures obtained by projecting the regular dodecahedron 3 onto the spherical surface 2, those
surfaces are not flat but curved. In arranging the transducers, first, the transducers are arranged
at the apexes A to E and the center of gravity F of the spherical pentagon 5 shown in FIG. 4A.
Next, as shown in FIG. 4B, points G to I, J to L, and M to O obtained by equally dividing each side
(arc) of the spherical triangle 6 (here, ΔFCD is illustrated) are divided equally. Arrange the
vibrator. The four divisions here are an example, and the number of divisions can be arbitrarily
selected. Furthermore, when these equally divided points are connected by line segments (arcs),
three small spherical triangles z are formed. Therefore, as shown in FIG. 4C, the barycentric
position P of these spherical triangles z, Transducers are placed on Q and R, respectively. For the
other spherical triangles 6, vibrators are arranged in the same procedure as in FIGS. 4 (a) and 4
(b). As a result, the arrangement of the ultrasonic transducers 10b as shown in FIG. 5 is obtained,
and the transducers 10b can be arranged at substantially equal intervals on the surface of the
hemispherical portion 1B.
[0025]
04-05-2019
9
Thus, using the spherical polygon obtained by projecting the regular polygons forming each face
of the regular polyhedron onto the sphere, the vertex and the center of gravity of this spherical
polygon and the spherical triangle which is a component of the spherical polygon A method of
arranging elements at points obtained by equally dividing each side of the and the centers of
gravity of small spherical triangles formed by arcs connecting these equally divided points is
referred to as "window center of gravity method". Details of the window centroid method are
described in Magnus J. Wenninger: Spherical Models, DOVER PUBLICATIONS, INC., Mineola, New
York (November 1999), pp 79-124.
[0026]
3 to 5 show the procedure of arranging the transducers on the basis of a regular dodecahedron,
but as can be seen from FIG. 4A, the spherical pentagon 5 corresponding to each surface of the
regular dodecahedron is 4 can be divided into five spherical triangles 6. Therefore, focusing on
this spherical triangle 6, it is possible to divide each spherical triangle 6 into a five-sided polygon
consisting of 5 × 12 = 60 isosceles triangles as shown in FIG. It has the same result as following
the steps (b) and (c). That is, when based on a 60 face, a small spherical triangle z formed by an
arc connecting the vertex of the spherical triangle 6 and each of the sides of the spherical
triangle 6 and the equal division points The vibrators are arranged at the center of gravity of and
respectively. From this, it is possible to arrange the transducers by the procedure of FIGS. 4B and
4C based on a regular icosahedron composed of 20 regular triangles instead of the regular
dodecahedron. However, in the case of a regular icosahedron, in order to have continuity with
the transducer array of the cylindrical portion 1A, it is necessary to orient the apex of the regular
icosahedron in the vertical direction, whereby the verticality of the transducers in the cylindrical
portion 1A The pitch is larger than the horizontal pitch (the opposite relationship to the case of a
regular dodecahedron). Therefore, in order to minimize the vertical pitch, it is preferable to base
on a regular dodecahedron.
[0027]
FIG. 6 is a diagram showing the transducer array of the cylindrical portion 1A and the
hemispherical portion 1B obtained by the above-described array algorithm. The vibrators 10a of
the cylindrical portion 1A are arranged such that the six vibrators adjacent to one vibrator are
positioned at each vertex of the regular hexagon 8 as described above, and the facing of the
regular hexagon 8 is performed. One set of sides 9 is arranged so as to face the vertical direction.
As a result, since the pitch α in the vertical direction is minimized, grating lobes generated in the
04-05-2019
10
vertical direction during horizontal scanning can be suppressed. On the other hand, the vibrator
10b of the hemispherical portion 1B is formed by an arc connecting the vertexes of the spherical
triangle 6 and the equal divisions of the sides of the spherical triangle 6 as described above, and
arcs connecting these equal division points They are respectively disposed at the center of
gravity of the spherical triangle. In FIG. 6, the position A is the center of the regular hexagon on
the side of the cylindrical portion 1A, and strictly speaking, it does not completely coincide with
the vertex position of the spherical pentagon 5 on the side of the hemispherical portion 1B.
According to the above, the positions of both can be made to substantially coincide. When the
transducers 10a and 10b of the cylindrical portion 1A and the hemispherical portion 1B are
arranged as described above, the array of the ultrasonic transducers 10a and 10b is continuous
from the cylindrical portion 1A to the hemispherical portion 1B as can be seen from FIG. The
variation of the element density in the vicinity of the boundary W between the cylindrical portion
1A and the hemispherical portion 1B can be reduced. For this reason, even when an ultrasonic
beam is transmitted and received through an opening that spans the cylindrical portion 1A and
the hemispherical portion 1B, the directivity deviation (variation in signal level) caused by the
discontinuity of the transducer arrangement is minimized. Good directional characteristics can be
obtained.
[0028]
When an ultrasonic beam is transmitted using the ultrasonic transducer 1 as described above,
PDM (Pulse Duration Modulation) or PWM (Pulse Width Modulation) can be used to control
transmission signals independently for all channels. An umbrella beam for full scan and a fan
beam for half scan are formed. Further, at the time of echo reception, weight control and phase
control are performed independently for each channel with respect to the ultrasonic transducer
10 in a predetermined opening for each beam direction, and multi-beam formation processing is
performed.
[0029]
By the way, in the case of the transducer 1 comprising the cylindrical portion 1A and the
hemispherical portion 1B as shown in FIG. 1, the ultrasonic transducer 10b is also present in the
lower portion of the transducer 1. For this reason, in either the full scan or half scan, depending
on the tilt angle, the level of the side lobe signal immediately below rises, and the echo from the
seabed tends to appear as a false image on the display screen. is there. To this end, it is possible
to reduce the level of the side lobe signal in the directly downward direction by shortening the
aperture length in the bottom direction orthogonal to the beam plane for both transmission and
04-05-2019
11
reception or adjusting the weight. FIG. 7 shows an example in which weighting is performed
using a Gaussian function as a weight function when transmitting an umbrella beam using the
entire region of the cylindrical portion 1A and a part of the hemispherical portion 1B.
[0030]
Also, in the case of a half-turn scan, nondirectional beam transmission is performed in a scan
range of approximately 180 °, but weighting is performed using the trapezoidal weight function
shown in FIG. A smooth directional pattern as shown in FIG. 8 (b) is obtained, and the directivity
deviation in the vicinity of the end (-90 ° and + 90 °) of the scan range is reduced as compared
to the case where a rectangular weight function is used. be able to.
[0031]
FIG. 9 shows a block circuit diagram of a scanning sonar S using the transducer 1 described
above.
In FIG. 9, reference numeral 10 denotes the aforementioned ultrasonic transducer (10a or 10b),
and one transmission / reception channel 100 (100a, 100b, 100c...) Is provided for each
transducer 10. Since the configuration of each transmission and reception channel is the same,
the transmission and reception channel 100a will be described below. In the transmission /
reception channel 100a, 11 is a transmission / reception switching circuit for switching between
transmission and reception operations, 12 is a transmission amplifier for giving a transmission
signal to the ultrasonic transducer 10, 13 is a driver circuit for driving the transmission amplifier
12, and 14 is a transducer 10 A preamplifier for amplifying the received signal, a band pass filter
15 for passing only a signal of a predetermined frequency band out of the output signal of the
preamplifier 14, an A / D converter for converting the signal passed through the band pass filter
15 into a digital signal, Reference numeral 17 denotes an interface for transmitting and receiving
signals to and from the circuit at the subsequent stage.
[0032]
The driver circuit 13 decodes a binarized drive code given from the transmission beam forming
unit 26 described later via the interfaces 20 and 17 into a drive signal for driving the FET of the
transmission amplifier 12. The transmission amplifier 12 is a full bridge type PDM (Pulse
Duration Modulation) transmission amplifier, and outputs a pulse width modulated transmission
04-05-2019
12
signal. The vibrator 10 is driven via the transmission / reception switching circuit 11 by this
signal. The transmission / reception switching circuit 11 guides the output signal of the
transmission amplifier 12 to the vibrator 10 in the transmission period, and guides the signal
output by the vibrator 10 in the reception period to the preamplifier 14 as a reception signal.
The preamplifier 14 amplifies this received signal, and the received signal from which noise
components other than the predetermined frequency band have been removed by the band pass
filter 15 is sampled at a predetermined sampling cycle in the A / D converter 16 and converted
into digital data. .
[0033]
Reference numeral 26 denotes a programmable transmission beam forming unit (hereinafter
referred to as "transmission beam forming unit"). And includes a transmission signal generation
unit 21, a waveform memory 24, and a transmission DSP (Digital Signal Processor) 25. The
transmission signal generation unit 21 is formed of, for example, an FPGA (Field Programmable
Gate Array), and includes a timing signal generation circuit 22 and a coefficient table 23. The
timing signal generation circuit 22 generates a signal as a reference of generation timing of the
transmission signal. The transmission DSP 25 is a digital signal processing circuit for generating
a transmission signal, and calculates a binarized reference driving code for generating a pulse
width modulation waveform for a predetermined kind of weight for each azimuth, Write to
waveform memory 24. Also, the transmission DSP 25 calculates the delay amount, weight value
and azimuth angle of each channel for transmission beam formation for each transmission cycle,
and writes the calculated amount in the coefficient table 23. The transmission signal generation
circuit 21 generates a drive code according to the weight value and the delay amount of each
channel based on the reference drive code corresponding to the azimuth angle of each channel.
[0034]
A buffer memory 27 is a memory for temporarily storing received data from each channel 100
through the interface 20. Reference numeral 28 denotes a programmable reception beam
forming unit (hereinafter referred to as "reception beam forming unit"). And includes a reception
DSP 29, a coefficient table 30, and a reception beam forming operation unit 31. The reception
beam forming operation unit 31 is formed of an FPGA. The reception DSP 29 calculates the
phase and weight of the reception signal output from each transducer 10 for each reception
beam, and writes these to the coefficient table 30. The reception beam forming operation unit 31
calculates the phase and weight written in the coefficient table 30 on the reception signal from
each transducer 10, and synthesizes the respective signals to obtain a synthesized reception
04-05-2019
13
signal. This combined reception signal is determined as time series data for each beam, and this
is written to the buffer memory 32.
[0035]
Reference numeral 33 denotes a programmable filter, which comprises a filter DSP 34, a
coefficient table 35, and a filter operation unit 36. The programmable filter 33 has a function of
performing predetermined band limitation and pulse compression for each beam. The filter DSP
34 calculates filter coefficients for obtaining predetermined band-pass filter characteristics for
each beam, and writes the filter coefficients in the coefficient table 35. The filter operation unit
36 performs an operation as an FIR (Finite Impulse Response) filter based on the coefficients of
the coefficient table 35 to obtain a band-processed reception signal. The filter operation unit 36
is formed of an FPGA.
[0036]
An envelope detection unit 40 detects an envelope of the band-processed reception signal of
each reception beam. Specifically, the envelope is detected by finding the square root of the sum
of the square of the real part and the square of the imaginary part of the time waveform.
[0037]
An image processing unit 41 converts received signal strength at each distance of each received
beam into image information and outputs it to the display unit 42. As a result, an image of
underwater information such as a school of fish in the detection area is displayed on the display
unit 42.
[0038]
An operation unit 37 operates keys of the operation unit 37 to input a beam tilt angle and the
like. The output from the operation unit 37 is sent to the host CPU 39, which is a control unit, via
the interface 38. The host CPU 39 controls the above-described units based on the input content
in the operation unit 37.
04-05-2019
14
[0039]
Although not shown in FIG. 9, the ship on which the scanning sonar S is mounted is equipped
with a detection device for detecting rolling and pitching of the hull, and the transmission DSP 25
is based on the output of the detection device. The coefficients to be written in the coefficient
table 23 are calculated so that the transmission beam is always formed in a predetermined
direction regardless of the ship's motion. Similarly, the receiving DSP 29 also calculates the
coefficients to be written in the coefficient table 30 based on the output of the detection device
so as to always form a receiving beam in a predetermined direction regardless of the motion of
the ship.
[0040]
By the way, in the above-mentioned scanning sonar S, as described above, in the cylindrical
portion 1A of the ultrasonic transducer 1, the pitch β in the horizontal direction of the
transducers 10a is larger than the pitch α in the vertical direction. A grating lobe generated in
the horizontal direction at the time of horizontal scanning becomes a problem. In order to solve
this problem, an azimuth-specific frequency transmission and reception method in which
transmission and reception are performed using signals of different frequencies depending on
the azimuth is an effective means. The azimuth frequency transmission / reception method is
described in JP-A-2003-337171. When this system is adopted, transmission control means
comprising transmission beam forming unit 26, driver circuit 13, transmission amplifier 12 and
the like generate transmission signals of different frequency bands for each direction. The
ultrasonic transducers 10 are driven to transmit ultrasonic beams having different frequencies
for each direction. Further, at the time of receiving an echo, the reception control means
including the reception beam forming unit 28, the programmable filter 33, etc. selects a
frequency for each direction and obtains a reception signal of a predetermined direction. In this
manner, transmission and reception are performed at different frequencies according to azimuth,
and signals of frequencies according to the azimuth to be received are selectively received,
thereby making the influence of signals from other azimuths less likely to occur, and horizontal
gratings The lobe can be reduced by about 20 dB.
[0041]
04-05-2019
15
The present invention can adopt various embodiments other than those described above. For
example, the signal frequency may be different between the case where the scanning sonar S
performs the full scan and the case where the half scan is performed. In this way, since the
signals used for the respective scans do not interfere with each other, it is possible to
simultaneously perform the full scan and the half scan by one transmission / reception. For this
reason, it becomes possible to perform wide range detection efficiently in a short time. In this
case, the transmission beam forming unit 26 constituting the transmission control means
generates transmission signals of different frequencies f1 and f2, and the driver circuit 13 and
the transmission amplifier 12 perform the transmission signal of the frequency f1 at the time of
the entire scan. The acoustic transducer 10 is driven, and at the time of half-turn scanning, the
ultrasonic transducer 10 is driven by the transmission signal of the frequency f2. The
programmable filter 33 constituting the reception control means extracts frequency components
corresponding to the frequencies f1 and f2 as a reception signal. The technique of concurrent
scanning as described above is described in Japanese Patent Laid-Open No. 2003-202370.
[0042]
In the embodiment described above, the scanning sonar is taken as an example of the underwater
detection device, but the ultrasonic transducer of the present invention is not limited to the
scanning sonar, and is an underwater detection device such as a fish finder, sounder, tidal meter
Can also be applied.
[0043]
It is a front appearance view showing an embodiment of a transducer concerning the present
invention.
It is a figure explaining the arrangement | sequence method of the vibrator | oscillator in the
cylindrical part of a transducer. It is a figure which shows the regular dodecahedron inscribed in
a spherical surface. It is a figure explaining the arrangement | sequence method of the vibrator |
oscillator in the hemispherical part of a transmitter-receiver. It is a figure which shows the
arrayed state of the vibrator | oscillator in the hemispherical part of a transducer. It is the figure
which showed the vibrator | oscillator arrangement | positioning of a cylindrical part and a
hemispherical part. It is a figure explaining the reduction method of a side lobe level. It is a figure
which shows the weight function and directivity characteristic in the case of a half-turn scan. It is
a block circuit diagram of the scanning sonar which used the transducer which concerns on this
invention. It is an external view which shows the conventional cylindrical transducer. It is an
external view which shows the conventional semi-cylindrical transducer. It is an external view
04-05-2019
16
which shows the conventional spherical transducer.
Explanation of sign
[0044]
DESCRIPTION OF SYMBOLS 1 ultrasonic transducer 1A cylindrical part 1B hemispherical part 2
spherical surface 3 positive 12 faces 4 positive pentagon 5 spherical 5 square 6 spherical
triangle 8 positive hexagon 10, 10a, 10b ultrasonic transducer 11 transmission / reception
switching circuit 12 transmission amplifier 13 driver circuit 14 preamplifier 15 band-pass filter
16 A / D converter 26 transmit beam forming unit 28 receive beam forming unit 33
programmable filter 39 host CPU 40 envelope detection unit 41 image processing unit 42
display unit S scanning sonar
04-05-2019
17
Документ
Категория
Без категории
Просмотров
0
Размер файла
32 Кб
Теги
jp2006208107
1/--страниц
Пожаловаться на содержимое документа