JP7434809B2 - Sonar devices, methods, and programs - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sonar device, method, and program.

As a technology related to sonar, for example, Patent Document 1 discloses a cross fan beam type underwater imaging sonar that uses a transmitter and a receiver in which a transmitting array and a receiving array are arranged orthogonally. Patent Document 2 includes a group of transmitters and a group of receivers disposed orthogonally to the group of transmitters, transmits a transmission sound whose frequency changes from F1 to F2 over time PW, and transmits a signal received from the group of receivers. A sonar system is disclosed that identifies and displays a target. This sonar system is configured to change the frequency of the transmitted sound from F1 to F2 over time PW and change the transmitted beam direction from +θ degrees to -θ degrees.

Furthermore, Non-Patent Document 1 discloses a transmitting array in which cylindrical transducers are vertically stacked to form a linear shape, and a receiving array formed by a horizontally long line array. A cross fan beam sonar is disclosed. In Non-Patent Document 1, by using a continuous wave as a detection transmission waveform, spatial information can be obtained continuously without any interruption in time.

Japanese Patent Application Publication No. 8-5728 Japanese Patent Application Publication No. 10-132930

Masashi Emura and 4 others, “Acoustic Imaging Using CTFM Sonar”, Proceedings of the Acoustical Society of Japan, Paper No. 3-5-6, March 2012

The use of unmanned aerial vehicles underwater is expanding, and they have been used in various fields such as seabed surveys. During the operation of this unmanned aircraft, it is desirable to continuously obtain underwater three-dimensional spatial information without any temporal interruption when docking with a fixed station or a mother ship.

With the methods of related technologies such as those disclosed in Patent Documents 1 and 2 described above, it is not possible to obtain temporally continuous information. In the method of Non-Patent Document 1, the spatial information that can be obtained is limited to two dimensions.

Therefore, an object of the present invention is to provide a sonar device, method, and program that can reduce the number of channels of an acoustic array and continuously acquire three-dimensional spatial information without any interruption in time.

According to one aspect of the present invention, a sonar device includes a transmitting array configured of a line array including a plurality of transmitting elements, a long side direction perpendicular to the transmitting array, and a short side direction having two channels or two channels. a receiving array constituted by a line array consisting of receiving elements of a small number of channels or more (about 4 channels at most); a transmitting section that transmits continuous wave transmission signals from the transmitting array; and a reception processing unit for processing. The reception processing unit generates a plurality of reception fan beams in the long side direction of the reception array for at least first and second subarrays generated in the short side direction in the reception array, and generates a plurality of reception fan beams in the long side direction of the reception array. a directional synthesis processing unit that generates a directional synthesis signal; a first azimuth detection unit that determines a target azimuth in the long side direction of the reception array based on the plurality of directional synthesis signals; a second azimuth detection unit that detects a target azimuth in the short side direction of the receiving array based on a phase difference between the first and second subarrays; Three-dimensional spatial information is acquired based on the target orientation and target distance in the side direction.

According to one aspect of the present invention, a transmitting array is configured of a line array including a plurality of transmitting elements, and a line array is configured of a line array including a plurality of transmitting elements, the long side direction of which is orthogonal to the transmitting array. A receiving array, a method for searching for a target using a sonar, the method comprising: transmitting a continuous wave transmission signal from the transmitting array; and processing the received signal received by the receiving array.
The receiving array has receiving elements of two channels or a small number of channels (about four channels at most) in the short side direction,
The processing of the received signal includes:
Within the receiving array, a plurality of receiving fan beams are generated in the long side direction of the receiving array for at least first and second subarrays generated in the short side direction, respectively, and a plurality of directional composite signals are generated. death,
determining a target orientation in the long side direction of the receiving array based on the plurality of directional composite signals;
detecting a target orientation in the short side direction of the receiving array based on a phase difference between the first and second subarrays of the receiving array;
A target search method is provided, which acquires three-dimensional spatial information based on the target orientation in the long side direction and the short side direction of the receiving array, and a target distance.

According to one aspect of the present invention, a transmitting array configured with a line array including a plurality of transmitting elements, a long side direction perpendicular to the transmitting array, and two or more channels in a short side direction. a receiving array configured with a line array consisting of receiving elements of a small number of channels (about 4 channels at most), transmitting a continuous wave transmission signal from the transmitting array, and processing the received signal received by the receiving array. To the computer that makes up the sonar,
As the processing of the received signal,
Within the receiving array, a plurality of receiving fan beams are generated in the long side direction of the receiving array for at least first and second subarrays generated in the short side direction, respectively, and a plurality of directional composite signals are generated. processing and
a process of determining a target orientation in the long side direction of the receiving array based on the plurality of directional composite signals;
a process of detecting a target orientation in the short side direction of the receiving array based on a phase difference between the first and second subarrays of the receiving array;
A program is provided that executes a process of acquiring three-dimensional spatial information based on the target orientation in the long side direction and the short side direction of the receiving array, and the target distance.

According to one embodiment of the present invention, a computer-readable program recording medium (for example, RAM (Random Access Memory), ROM (Read Only Memory), or EEPROM (Electrically Erasable and Programmable ROM)) storing the above program is provided. Non-transitory media such as semiconductor storage, HDD (Hard Disk Drive), CD (Compact Disc), and DVD (Digital Versatile Disc) are provided.

According to the present invention, it is possible to realize a sonar that can continuously acquire three-dimensional spatial information without interruption in time by reducing the number of channels of an acoustic array.

FIG. 1 is a diagram illustrating the configuration of an embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration example of a transmitting array and a receiving array according to an embodiment of the present invention. FIG. 3 is a diagram illustrating frequency modulation according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a transmission fan beam in an embodiment of the present invention. FIG. 3 is a diagram illustrating a reception processing unit in an embodiment of the present invention. FIG. 3 is a diagram illustrating a subarray of a receiving array in an embodiment of the present invention. FIG. 3 is a diagram illustrating a reception fan beam in an embodiment of the present invention. It is a figure explaining phase detection processing in one embodiment of the present invention. It is a figure explaining the modification 1 of one embodiment of this invention. It is a figure explaining the modification 2 of one embodiment of this invention. It is a figure explaining the modification 3 of one Embodiment of this invention. It is a figure explaining the modification 4 of one embodiment of this invention. FIG. 2 is a diagram illustrating an example of computer implementation of an embodiment of the present invention.

Embodiments of the present invention will be described. In one form of the present invention, the receiving array constituting the sonar device is a rectangular array with a short side configured with two channels or a small number of channels (for example, about 2 to 4 channels) with two or more channels. . The transmitting array consists of a line array extending in a direction orthogonal to the receiving array. The receiving array receives reflected waves from the target in response to frequency modulated continuous wave transmission signals transmitted from the transmitting array. In signal processing of the received signal, a plurality of reception fan beams are generated in the long side direction of the reception array 102, and the orientation (for example, left and right) of the target in the long side direction of the reception array 102 is obtained. In addition, in the signal processing, for example, the target orientation (for example, up and down) in the short side direction of the receiving array 102 is obtained from the phase difference between the two stages of wave receiving elements on the short side, and furthermore, a replica signal of the continuous wave transmission signal is obtained. and find the distance to the target from the received signal. Three-dimensional spatial information is then obtained from this information (left/right, up/down direction and distance). According to the present invention, an acoustic array (with a small number of channels) consisting of a receiving array consisting of a line array whose short side consists of two channels or a small number of channels of two or more channels, and a transmitting array orthogonal to the receiving array is used. With a sonar device, three-dimensional spatial information can be acquired continuously without any interruption in time.

FIG. 1 is a diagram schematically showing an example of the configuration of a sonar device 10 according to an embodiment of the present invention. The transmission array 101 is an array of acoustic elements (also referred to as "wave transmission elements") that perform electro-acoustic conversion of transmission signals (electrical signals). The receiving array 102 is an array of acoustic elements (also referred to as "receiving elements") that perform acoustic-to-electrical conversion of received signals (acoustic signals). The transmitting unit 103 generates a transmitting signal (electrical signal) to be transmitted from each channel (wave transmitting element) of the transmitting array 101. The receiving unit 104 performs analog-to-digital conversion on the received signal of each channel (receiving element) of the receiving array 102. The reception processing section 105 performs signal processing on the received signal digitized by the reception section 104. The transmission/reception control unit 106 controls processing parameters, timing, etc. for the transmission unit 103 and the reception processing unit 105. The operation/display unit 107 generates and displays a three-dimensional image based on the start of the operation of the sonar device 10, the target direction (left/right, up/down) calculated by the reception processing unit 105, and distance information to the target. Output to a device (not shown). The operation/display unit 107 and the transmission/reception control unit 106 may be configured to be communicatively connected by wire or wirelessly.

FIG. 2 is a diagram schematically showing an example of the transmitting array 101 and receiving array 102 of FIG. 1. The transmitting array 101 is a line array in which a plurality of acoustic elements (wave transmitting elements) are arranged one-dimensionally. The receiving array 102 is a line array whose long sides are perpendicular to the longitudinal direction of the transmitting array 101 and whose short sides are composed of two channels (two stages of upper and lower receiving elements). Note that the transmission array 101 is arranged with its longitudinal direction along the Z axis in the drawing. For example, the Z axis can correspond to the top and bottom. In the receiving array 102, a plurality of sets of receiving elements in two stages, upper and lower, are arranged along the Y axis in the drawing. The Y axis can be made to correspond to the left and right. In FIG. 2, the normal vectors of the wave transmitting surfaces of the transmitting elements of the transmitting array 101 and the receiving surfaces of the wave receiving elements of the receiving array 102 are vectors pointing in the positive direction of the X-axis in the drawing. Note that the receiving array 102 may be configured with a small number of channels (2 to 4 stages of wave receiving elements) of two or more channels or at most four channels on the short side.

FIG. 3 is a diagram showing an example of time-frequency signal information of a transmission waveform transmitted from the transmission array 101. The transmitter 103 transmits continuously without any interruption while changing the frequency linearly.

FIG. 3A shows a time course of the frequency of a CTFM (Continuous Transmission Frequency Modulated) waveform, which is a common continuous wave transmission waveform (vertical axis: frequency, horizontal axis: time). A frequency sweep from the start frequency f ₁ to the end frequency f ₂ is repeated every cycle T (T: chirp period) (continuous chirp waveform). f _w (= f ₂ - f ₁ ) is the frequency sweep width (bandwidth). The slope S of the chirp waveform is given by S = f _w /T. FIG. 3B illustrates two periods of a continuous wave transmission waveform (chirp waveform).

FIG. 3C illustrates a part (two cycles) of a replica signal of a continuous wave transmission signal and a received waveform (reflected wave from a target) (vertical axis: frequency, horizontal axis: time). From the frequency difference f _B (beat frequency) between the transmitted and received waveforms, the distance R to the target (reflection point) is R = c*T*f _B /(2f _W ) (where c is the speed of sound and T is The chirp period, f _W is the frequency sweep width). Note that the continuous wave transmission waveform is not limited to CTFM, and may be a continuous waveform other than CTFM such as a GSFM (Generalized Sinusoidal Frequency-Modulated) waveform or frequency hopping.

FIG. 4 is a diagram schematically showing a transmission fan beam 401 transmitted from the transmission array 101. As shown in FIG. 4, the transmission fan beam 401 consists of a fan-shaped acoustic beam that is wide in the Y-axis direction (horizontal direction) and narrower in the z-axis direction (vertical direction) than in the left-right direction.

FIG. 5 is a diagram illustrating an example of processing by the reception processing section 105 in FIG. 1. The demodulation processing unit 1051 performs demodulation (orthogonal demodulation) using a transmission waveform that is generally used in continuous wave transmission using a CTFM waveform as a source signal. The demodulation processing unit 1051 includes a mixer (not shown) that multiplies the replica signal of the transmitted waveform and the received signal (complex multiplication), and outputs a signal corresponding to the difference in frequency (beat frequency) between the replica signal and the received signal from the mixer. You may also do so. Information on the frequency difference between the frequency-modulated continuous wave transmission signal and the reception signal can be obtained while retaining the phase information for each channel of the reception array 102.

The directivity synthesis processing unit 1052 generates a plurality of reception fan beams that have wide directivity in the up-down (vertical: Z-axis) direction and narrow directivity in the left-right (horizontal: Y-axis) direction. For example, _if the direction of arrival of the beam (direction with respect to the X-axis on the XY plane in FIG. The distance difference r _m between the received waves (reflected waves) between the wave elements is r _m = (m-1)*d _R *sin(γ). A receiving fan beam s(γ) in the γ direction is generated by adding the signals whose phases of the received signals at the receiving elements are corrected by this distance difference (additive directional synthesis). The directivity synthesis processing unit 1052 generates a directivity synthesis signal from the selected channel and the front direction of the beam. Note that the directional composite signal corresponds to a composite beam (cross beam) that has sharp directivity at the intersection of the transmit fan beam and the receive fan beam.

The first orientation detection unit (left and right) 1053 detects the target orientation in the left and right direction from the plurality of directional composite signals (beams) generated by the directional composite processing unit 1052. That is, the azimuth detection unit (left and right) 1053 detects the azimuth of the target (reflection point) in the left and right direction from the output level of the directional composite signal (beam).

The phase detection unit 1054 detects the phase difference between designated beams in the reception array 102. The phase detection unit 1054 detects the phase difference between specified beams among the upper and lower channels (receiving elements) of the receiving array 102 .

The second azimuth detection unit (up and down) 1055 calculates the arrival azimuth in the up and down direction (vertical direction: Z-axis direction) from the phase difference between the specified beams.

FIG. 6 is a diagram illustrating a subarray configuration (channel) in the directional synthesis processing section 1052. The two-stage receiving array 102 is vertically separated to form separate sub-array 1 (601) and sub-array 2 (602).

FIG. 7 is a diagram schematically illustrating a reception fan beam generated by the directional synthesis processing section 1052. As shown in FIG. 7, the directivity synthesis processing unit 1052 configures the receiving fan for each of sub-array 1 and sub-array 2 in FIG. Generate a beam.

FIG. 8 is a diagram schematically explaining the phase difference of received signals between beams whose beam centers are in the same direction in the left-right direction (Y-axis direction) among the beams generated by sub-arrays 1 and 2 in FIG. 6. . The arrival direction of the received wave in the short side direction of the receiving array 102 is detected from the phase difference between the upper and lower two stages of receiving elements (interval=d _Z ). If the direction of arrival in the Z direction is θ with respect to the X axis, which is the normal to the YZ plane, the phase difference in the figure is given by d _Z *sin(θ).

Although the sonar device 10 according to the present embodiment uses a continuous wave as a transmission waveform, depending on the operation mode, it is also possible to perform transmission and reception using a pulse waveform in the same sonar device 10. In this case, a general pulse is transmitted from the transmission array 101 while changing the beam center direction and transmission frequency of the transmission beam, and the reception array 102 generates reception fan beams for multiple directions and performs reception processing. It can take the form of a three-dimensional cross-fan sonar using a transmission method. In this case as well, by generating the upper and lower subarrays shown in FIG. 6, it is possible to improve the azimuth accuracy in the vertical direction and suppress false detection (recognizing something that is not a target as a target). Note that if the transmitted signal is not a continuous wave but a pulse waveform, the distance R to the target is R = c*τ/2 (c is the speed of sound).

According to the present embodiment, a received signal from a continuous wave transmission signal is detected by three steps: azimuth detection processing using beams generated in the horizontal direction, azimuth detection processing and distance detection processing based on the phase difference of sub-arrays arranged in the vertical direction. Acquire dimensional spatial information without temporal interruption.

<Modification 1>
FIG. 9 is a diagram illustrating an example of generation of subarrays of the reception array when subarrays are also generated in the long side direction of the reception array 102. In the receiving array 102, subarrays 1 to 4 are generated within the receiving array 102 (hatched receiving elements are selected as the corresponding subarrays). Note that the receiving array 102 includes a plurality of subarrays in which combinations of receiving elements included in the subarrays differ in the long side direction. In subarrays 1 and 2, the wave receiving element at the right end of the drawing is unselected, and in subarrays 3 and 4, the wave receiving element at the left end of the drawing is unselected. In this modification example 1, the first azimuth detection unit 1053 in FIG. 5 detects the azimuth in the long side direction of the receiving array 102 from the phase information for each beam of the subarrays in the long side direction of the receiving array 102.

In the embodiment, the reception array 102 includes two subarrays 1 and 2 (FIG. 6) in the short side direction, and the first direction detection unit 1053 detects a plurality of orientations in the left and right direction (Y-axis direction) of each subarray. Target direction information is obtained based on the composite signal (beam). On the other hand, in this modification example 1, the first azimuth detection unit 1053 detects the orientation generated by the directivity synthesis processing unit 1052 with respect to the subarrays (subarrays 1, 3, subarrays 2, 4) in the long side direction of the receiving array 102. The configuration is such that the orientation in the long side direction (left-right direction: Y-axis direction) is also detected using phase information for each gender composite signal (beam). Therefore, according to the first modification, the accuracy of detecting the orientation in the long side direction (left-right direction: Y-axis direction) can be improved.

<Modification 2>
FIG. 10 is a diagram schematically showing a vertical beam pattern of a transmission beam when the viewing angle in the vertical direction (Z-axis direction) is expanded. In the example of FIG. 10, three transmission beams are transmitted: an upward transmission fan beam U 1001, a forward transmission fan beam C 1002, and a downward transmission fan beam D 1003. When the beam is tilted at an angle δ from the normal direction of the transmitting surface of the transmitting array 101, when the interval between the transmitting elements is d _T and the wavelength is λ, the transmitted signal of the k-th transmitting element of the transmitting array 101 is the first one. The phase adjustment of (k-1)*d _T *sin(δ)/λ may be performed on the transmission signal of the wave transmitting element.

<Modification 3>
FIG. 11 is a diagram illustrating time-frequency signals of transmission waveforms for each transmission beam in FIG. 10. In the embodiment described above, transmission was performed using only one beam, but in this embodiment, a plurality of transmission fan beams (three transmission beams U, C, and D in FIG. 10) are transmitted from the transmission array 101 in the vertical direction. Each is transmitted in a different frequency band while changing its direction. Regarding the transmission beams (fan beams) U, C, and D, the frequency bands (sweep frequency widths) of their continuous chirp waveforms are different from each other. It goes without saying that the frequency band allocation of the transmission beams (fan beams) U, C, and D is not limited to that shown in FIG. 11.

According to this modification 3, compared to the embodiment described with reference to FIG. 4, it is possible to obtain a wider coverage area of the sensor in the vertical direction.

<Modification 4>
In FIG. 12, the line array is arranged in an annular shape. The acoustic array is composed of a transmitting array 101 and a receiving array 102 arranged orthogonally to the transmitting array 101, and each line array constitutes a part of a ring. In this way, the acoustic array can take a shape suitable for the vehicle on which the sonar device is mounted.

FIG. 13 is a diagram illustrating an example in which the sonar device 10 described above is configured by a computer 300. The computer 300 includes a processor 301, a memory 302, a display device 303, and a communication interface 304. Memory 302 stores programs to be executed by processor 301. The processor 301 performs processing in the reception processing unit 105, control in the transmission and reception control unit 106, and the like. A communication interface 304 communicates with the transmitter 103 and the receiver 104. The memory 302 may be, for example, a RAM, a ROM, a semiconductor storage such as an EEPROM, or an HDD. Note that the processor 301 may perform processing in the operation/display unit 107 (such as converting three-dimensional spatial information into an image and displaying it on the display device 303).

The sonar device 10 of the embodiment described above is aimed at detecting objects underwater, and is particularly effective in detecting targets at short distances. However, it is not limited to short range detection, and can also be used for target detection at long distances. Further, although the above embodiment describes an example of application to underwater acoustics, the same sensor device and signal processing method can also be applied to a case where acoustics are utilized in the air. It is also applicable to cases where electromagnetic waves are used instead of sound waves.

In addition, each disclosure of the above-mentioned Patent Documents 1 and 2 and Non-Patent Document 1 is incorporated into this document by reference. Within the scope of the entire disclosure of the present invention (including the claims), changes and adjustments to the embodiments and examples are possible based on the basic technical idea thereof. Further, various combinations and selections of various disclosed elements (including each element of each claim, each element of each embodiment, each element of each drawing, etc.) are possible within the scope of the claims of the present invention. . That is, it goes without saying that the present invention includes the entire disclosure including the claims and various modifications and modifications that a person skilled in the art would be able to make in accordance with the technical idea.

10 sonar device 101 transmission array 102 reception array 103 transmission section 104 reception section 105 reception processing section 106 transmission/reception control section 107 operation/display section 300 computer 301 processor 302 memory 303 display device 304 communication interface 401 transmission fan beam 701 reception fan beam 601, 901 Subarray 1
602, 902 Subarray 2
903 Subarray 3
904 Subarray 4
1001 Transmission fan beam U
1002 Transmission fan beam C
1003 Transmission fan beam D
1021 Subarray 1
1022 Subarray 2
1051 Demodulation processing section 1052 Directivity synthesis processing section 1053 First direction detection section (left and right)
1054 Phase detection section 1055 Second direction detection section (up and down)

Claims (8)

A transmitting array composed of a line array consisting of a plurality of transmitting elements,
The long side direction is perpendicular to the longitudinal direction of the transmitting array, and the plurality of sets of receiving elements are arranged in the short side direction in multiple stages of upper and lower sides, and the plurality of sets of receiving elements in the plural stages in the short side direction are arranged in the long side direction. a receiving array consisting of a line array consisting of multiple rows of rows;
a transmitting unit that transmits a continuous wave transmission signal from the transmitting array;
a reception processing unit that processes the reception signal received by the reception array;
Equipped with
The plurality of upper and lower stages in the short side direction of the receiving array consists of either 2 to 4 upper and lower stages,
The reception processing unit includes:
directivity of a plurality of reception beams in the long side direction of the reception array for at least first and second sub-arrays each consisting of at least two rows of the plurality of rows of the line array of the reception array; a directional synthesis processing unit that generates by synthesis;
a first azimuth detection unit that determines a target azimuth in the long side direction of the reception array based on output levels of the plurality of reception beams;
a second orientation detection unit that detects a target orientation in the short side direction of the reception array based on a phase difference between the first and second subarrays of the reception array;
Equipped with
The at least first and second subarrays are arranged to be shifted by at least one receiving element in the longitudinal direction,
The first azimuth detection unit also detects the target azimuth in the long side direction using phase information for each of the reception beams generated by the directional synthesis processing unit for the at least first and second subarrays. ,
A sonar device characterized in that three-dimensional spatial information is acquired based on the target direction and target distance in the long side direction and the short side direction of the receiving array. the at least first and second subarrays include a portion of the plurality of sets of receiving elements in the long side direction of the receiving array;
The sonar device according to claim 1, wherein the at least first and second sub-arrays have different combinations of receiving elements included in at least an end portion of each sub-array in the long side direction of the receiving array. . 3. The sonar device according to claim 1, wherein the transmitter transmits a plurality of transmission beams made up of continuous waves in different frequency bands in different directions. 4. The sonar device according to claim 1, wherein each of the line arrays constitutes a part of a ring. A transmitting array composed of a line array consisting of a plurality of transmitting elements,
The long side direction is perpendicular to the longitudinal direction of the transmitting array, and the plurality of sets of receiving elements are arranged in the short side direction in multiple stages of upper and lower sides, and the plurality of sets of receiving elements in the plural stages in the short side direction are arranged in the long side direction. a receiving array consisting of a line array consisting of multiple rows of rows;
Equipped with
The plurality of upper and lower stages in the short side direction of the receiving array consists of either 2 to 4 upper and lower stages,
A method for searching for a target using a sonar, the method comprising transmitting a continuous wave transmission signal from the transmission array and processing the reception signal received by the reception array, the method comprising:
The processing of the received signal includes:
directivity of a plurality of reception beams in the long side direction of the reception array for at least first and second sub-arrays each consisting of at least two rows of the plurality of rows of the line array of the reception array; produced by synthesis,
Determining a target orientation in the long side direction of the receiving array based on the output levels of the plurality of receiving beams,
detecting a target orientation in the short side direction of the receiving array based on a phase difference between the first and second subarrays of the receiving array;
The at least first and second subarrays are arranged to be shifted by at least one receiving element in the longitudinal direction,
Detecting the target orientation in the long side direction based on phase information for each of the receiving beams generated by the directional synthesis for the at least first and second subarrays;
A method for searching for a target, characterized in that three-dimensional spatial information is acquired based on the target direction and target distance in the long side direction and the short side direction of the receiving array. the at least first and second subarrays include a portion of the plurality of sets of receiving elements in the long side direction of the receiving array;
6. The target search according to claim 5, wherein the at least first and second sub-arrays have different combinations of receiving elements included in at least an end portion of each sub-array in the long side direction of the receiving array. Method. 7. The target searching method according to claim 5, further comprising transmitting a plurality of transmission beams composed of continuous waves in mutually different frequency bands in mutually different directions. A transmitting array composed of a line array consisting of a plurality of transmitting elements,
The long side direction is orthogonal to the longitudinal direction of the transmitting array, and the short side direction is composed of sets of receiving elements in multiple stages of upper and lower sides, and a plurality of sets of receiving elements in multiple stages in the short side direction are arranged in the long side direction. a receiving array consisting of a line array consisting of multiple rows of rows;
a transmitting unit that transmits a continuous wave transmission signal from the transmitting array;
a receiving unit that converts the received signal received by the receiving array into a digital signal;
a computer comprising a processor, a memory storing a program, and a communication interface that communicates with the transmitter and the receiver;
Equipped with
The plurality of upper and lower stages in the short side direction of the receiving array is composed of either 2 to 4 upper and lower stages, and is a sonar that transmits a continuous wave transmission signal from the transmission array and processes the reception signal received by the reception array. a processor of said computer of the apparatus;
directivity of a plurality of reception beams in the long side direction of the reception array for at least first and second sub-arrays each consisting of at least two rows of the plurality of rows of the line array of the reception array; Processing to generate by synthesis,
A process of determining a target direction of the receiving array in the long side direction based on the output level of the plurality of receiving beams;
a process of detecting a target orientation in the short side direction of the receiving array based on a phase difference between the first and second subarrays of the receiving array;
A target in the long side direction based on phase information for each of the receiving beams generated by the directional synthesis for the at least first and second subarrays arranged in a state shifted by at least one receiving element in the longitudinal direction. Processing that also detects the direction,
A program for executing processing for acquiring three-dimensional spatial information based on a target direction and a target distance in the long side direction and the short side direction of the receiving array.

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