Target detection device, target detection method, and program

Abstract

To provide a target detection device, a target detection method, and a program capable of easily adjusting an angle range that can be probed in a finite band of the device.SOLUTION: A target detection device 1 includes: a transmission signal generation unit 103 for generating a transmission signal; a transmission array 10 having a plurality of transmission elements 11 for converting the transmission signal into a transmission wave and having at least a start transmission element 11a and an end transmission element 11b; a switch 104 for supplying the transmission signal to the plurality of transmission elements 11 in order from the start transmission element 11a to the end transmission element 11b; and a control unit 101 for controlling a sweep time of the switch 104 which is a time from the supply of the transmission signal to the start transmission element 11a to the supply of the transmission signal to the end transmission element 11b.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a target detection device, a target detection method, and a program for transmitting a transmission wave and detecting a target based on the reflected wave. [Background technology]

[0002] A target detection device that transmits a transmission wave and detects a target based on the reflected wave is known. In this type of target detection device, for example, a configuration may be used in which a source of the transmission wave is moved in one direction to change the frequency of the transmission wave transmitted into the water.

[0003] For example, a wave transmitting array is formed by arranging multiple wave transmitting elements (ultrasonic transducers) in one direction. A transmission signal is applied to these wave transmitting elements in sequence in the arrangement direction. This causes the source of the transmission wave to move in the arrangement direction. Due to the Doppler effect caused by this movement, the frequency of the transmission wave sent into the water changes within the angular range of the arrangement direction.

[0004] A receiving array is formed by arranging multiple receiving elements (ultrasonic transducers) in a direction perpendicular to the arrangement of the transmitting elements. In response to the above-mentioned transmission from the transmitting elements, a receiving signal is output from each receiving element. From these receiving signals, frequency components corresponding to each angle in the above-mentioned angle range are extracted by a band-limiting filter. In this way, receiving signals contained in an iso-frequency plane for each angle are obtained. Furthermore, beamforming is performed on the receiving signals of each iso-frequency plane to obtain receiving signals in an angular direction along the corresponding iso-frequency plane.

[0005] In this way, in the angular range (detection range) of the arrangement direction of the transmitting elements and the receiving elements, a received signal based on the echo is acquired at a predetermined angular resolution based on the band-limiting filter and beamforming. From this received signal, intensity data (volume data) of the echo distributed three-dimensionally in the detection range is acquired. By imaging this intensity data (volume data), an image showing the state of the target in the detection range can be obtained.

[0006] Patent Document 1 listed below discloses this type of target detection device. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2021 / 019858 Summary of the Invention [Problem to be solved by the invention]

[0008] In the target detection device as described above, the range in which the target can be searched is limited to a band specific to the device. Such band limitation is based on, for example, the operable band of the transmitting element and the receiving element. Therefore, when it is necessary to adjust the searchable range, it is necessary to adjust the band specific to the device. However, this adjustment is not easy to perform because it involves changing the hardware.

[0009] In view of the above problems, an object of the present invention is to provide a target detection device, a target detection method, and a program that can easily adjust the angle range that can be searched within a finite bandwidth of the device. [Means for solving the problem]

[0010] A first aspect of the present invention relates to a target detection device. The target detection device according to this aspect includes a transmission signal generation unit that generates a transmission signal, a wave transmitting array having a plurality of wave transmitting elements that convert the transmission signal into a transmission wave and having at least a start wave transmitting element and an end wave transmitting element, a switch that supplies the transmission signal to the plurality of wave transmitting elements in order from the start wave transmitting element to the end wave transmitting element, and a control unit that controls a sweep time of the switch, which is the time from the supply of the transmission signal to the start wave transmitting element to the supply of the transmission signal to the end wave transmitting element.

[0011] According to the target detection device of the first aspect, the searchable angle range corresponding to the arrangement direction (sweep direction) of the wave transmitting elements can be changed in a finite band of the device by changing the sweep time of the switch. Therefore, the searchable angle range in a finite band of the device can be easily adjusted.

[0012] In the target detection device according to this aspect, the sweep time sets an angle range over which the transmission wave is transmitted.

[0013] Here, when the control unit lengthens the sweep time, the angle range is expanded.

[0014] In this way, by controlling the sweep time, the angle range in which the transmission wave is transmitted can be widened or narrowed, and therefore the angle range in which the search can be performed for target detection can be changed with simple control.

[0015] In this configuration, the target detection device may further include an input unit used by a user to input a value corresponding to the sweep time or the angle range.

[0016] According to this configuration, the user can set the searchable angle range to a desired angle range.

[0017] In the target detection device according to this aspect, the control unit may be configured to further control a frequency of the transmission signal.

[0018] Here, the frequency of the transmission signal sets the center direction of the angular range in which the transmission wave is transmitted.

[0019] In this way, by controlling the frequency of the transmission signal, the center direction of the angular range of the transmission wave can be easily adjusted.

[0020] In this configuration, at a first timing, the control unit may be configured to set the frequency of the transmission signal to a first frequency for transmitting the transmission wave in the central direction of a first direction, and at a second timing after the first timing, the control unit may be configured to set the frequency of the transmission signal to a second frequency different from the first frequency for transmitting the transmission wave in the central direction of a second direction different from the first direction.

[0021] According to this configuration, since the central direction of the angular range of the transmission wave differs between the first timing and the second timing, the searchable angular range can be set to a wide angular range across all of these angular ranges.

[0022] The target detection device of this embodiment may further include a receiving array including at least one receiving element that receives a reflected wave generated by reflection of the transmitted wave at a target and converts the reflected wave into a received signal, and a processing circuit that extracts frequency components of the received signal to determine the direction of arrival of the reflected wave.

[0023] According to this configuration, a target object existing within the angular range of the transmitted wave can be detected from the received signal output by the wave receiving element.

[0024] The target detection device according to this embodiment is, for example, a sonar that detects targets in water.

[0025] A second aspect of the present invention relates to a target detection method, in which a transmission signal is supplied to a plurality of wave-transmitting elements that convert a transmission signal into a transmission wave in order from a start wave-transmitting element to an end wave-transmitting element, and a sweep time that is a time from the supply of the transmission signal to the start wave-transmitting element to the supply of the transmission signal to the end wave-transmitting element is controlled.

[0026] According to the target detection method according to the second aspect, the sweep time of the wave transmitting elements is controlled in the same manner as in the first aspect, so that the angle range that can be searched in the finite band of the device can be easily adjusted in the same manner as in the first aspect.

[0027] A third aspect of the present invention relates to a program for causing a control unit of a target detection device to execute a predetermined function. The program according to this aspect causes the control unit to execute a function of supplying a transmission signal to a plurality of wave-transmitting elements, which convert a transmission signal into a transmission wave, in order from a start wave-transmitting element to an end wave-transmitting element, and a function of controlling a sweep time, which is a time from supplying the transmission signal to the start wave-transmitting element to supplying the transmission signal to the end wave-transmitting element.

[0028] According to the program of the third aspect, the sweep time of the wave transmitting elements is controlled in the same manner as in the first aspect, so that the angle range that can be searched in the finite band of the device can be easily adjusted in the same manner as in the first aspect. Effect of the Invention

[0029] As described above, according to the present invention, it is possible to provide a target detection device, a target detection method, and a program that are capable of easily adjusting the range that can be searched in a finite band.

[0030] The effects and significance of the present invention will become clearer from the following description of the embodiment. However, the embodiment described below is merely an example of how the present invention can be put into practice, and the present invention is not limited to the embodiment described below. [Brief description of the drawings]

[0031]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Figure 25

[0032] The functions provided by the components described herein may be implemented in circuits or processing circuitry, including general purpose processors, application specific processors, integrated circuits, Application Specific Integrated Circuits (ASICs), a Central Processing Unit (CPU), conventional circuits, and / or combinations thereof, programmed to provide the functions described. Processors include transistors and other circuits and are considered to be circuits or processing circuitry. Processors may be programmable processors that execute programs stored in memory.

[0033] In this specification, circuits, units, and means are hardware that is programmed to realize the described functions or that performs this function, which may be any hardware disclosed in this specification or any hardware that is programmed to realize the described functions or that is known to perform this function.

[0034] If the hardware is a processor considered to be a type of circuit, the circuit, means, or unit is a combination of the hardware and the software used to configure the hardware and / or the processor.

[0035] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the following preferred embodiments, a target detection device is shown as being used as a sonar for detecting targets in water.

[0036] FIG. 1 is a diagram showing a usage form of the target detection device.

[0037] In this embodiment, a transducer 30 is installed on the bottom of the ship 2. The transducer 30 transmits a transmission beam (ultrasonic wave) TB1 underwater. The transducer 30 receives a reflected wave (echo) of the transmission beam TB1 reflected by the seabed 3 or a school of fish 4, and outputs a received signal. The target detection device generates an echo image showing the intensity distribution of the echo in the water based on the received signal, and displays it on the display unit. The components of the target detection device other than the transducer 30 and the display unit are equipped in a control device installed in the wheelhouse 2a of the ship 2. The display unit is installed in the wheelhouse 2a separately from the control device. The display unit may be integrated into the control device.

[0038] 2(a) and 2(b) are plan views that diagrammatically show the configuration of the transducer 30. FIG.

[0039] The transmitter / receiver 30 includes a transmitting array 10 and a receiving array 20. The transmitting array 10 is configured with a plurality of transmitting elements 11 arranged in a row. The receiving array 20 is configured with a plurality of receiving elements 21 arranged in a row. The transmitting elements 11 and the receiving elements 21 are ultrasonic transducers. The direction in which the transmitting elements 11 are arranged and the direction in which the receiving elements 21 are arranged are substantially perpendicular to each other. The transmitting elements 11 and the receiving elements 21 may be arranged on the same plane. However, the arrangement of the transmitting elements 11 and the receiving elements 21 is not limited to this. For example, the angle between the direction in which the transmitting elements 11 are arranged and the direction in which the receiving elements 21 are arranged may be 45°, 60°, or the like in a plan view.

[0040] FIG. 2(a) shows a configuration example of the transmission array 10 and the reception array 20 when a plurality of transmission elements 11 are arranged in the elevation angle direction (vertical direction). FIG. 2(b) shows a configuration example of the transmission array 10 and the reception array 20 when a plurality of transmission elements 11 are arranged in the azimuth angle direction (horizontal direction). Transmission signals are sequentially supplied to the plurality of transmission elements 11 from the start transmission element 11a to the end transmission element 11b. As a result, the transmission source (sound source) of the transmission wave moves in the direction D1 in which the plurality of transmission elements 11 are arranged. Thereby, the frequency of the transmission wave changes due to the Doppler effect. In the configuration of FIG. 2(a), the frequency of the transmission wave changes in the elevation angle direction, and in the configuration of FIG. 2(b), the frequency of the transmission wave changes in the azimuth angle direction.

[0041] FIG. 3 is a diagram for explaining the relationship between the frequency of the transmission wave and the direction of the angle θ.

[0042] Transmission signals are sequentially supplied to the plurality of transmission elements 11 constituting the transmission array 10 from the start transmission element 11a to the end transmission element 11b. As a result, the transmission source S (sound source) of the transmission wave moves in the moving direction D1 which is the arrangement direction of the plurality of transmission elements 11. As shown in the upper part of FIG. 3, when the X-axis is set in the moving direction D1, by sequentially supplying transmission signals from the start transmission element 11a to the end transmission element 11b, the transmission source S of the transmission wave moves in the X-axis direction. Here, the frequency of the transmission signal is constant.

[0043] The moving speed V of the transmission source S is higher as the sweep time, which is the time from supplying the transmission signal to the start transmission element 11a to supplying the transmission signal to the end transmission element 11b, is shorter. In other words, the higher the sweep speed, which is the speed of switching the transmission element 11 to which the transmission signal is supplied, the higher the moving speed V of the transmission source S.

[0044] As described above, when the transmission source S is moved in the moving direction D1, a change in frequency based on the Doppler effect occurs in the transmission wave observed at an observation position separated from the transmission source S by a predetermined distance.

[0045] That is, when the distance between the transmission source S and the observation position is sufficiently large, at an observation position in front (Z-axis direction) of the intermediate position of the movement range (hereinafter referred to as the "front observation position"), no change in frequency occurs due to the Doppler effect, and a transmission wave with the same frequency f0 as the transmission signal is generated. In contrast, at an observation position displaced in the opposite direction to the movement direction from the front observation position (hereinafter referred to as the "negative observation position"), the transmission source S moves in a direction away from the observation position, so that a transmission wave with a frequency lower than the frequency f0 of the transmission signal is generated due to the Doppler effect. Also, at an observation position displaced in the same direction as the movement direction from the front observation position (hereinafter referred to as the "positive observation position"), the transmission source S moves in a direction approaching the observation position, so that a transmission wave with a frequency higher than the frequency f0 of the transmission signal is generated due to the Doppler effect.

[0046] Here, if the angle θ is set as shown in Figure 3, with the angle tilted in the positive direction of the X-axis with respect to the Z-axis as positive, the speed c(θ) of the transmitted wave in the direction of angle θ from the intermediate position is calculated by multiplying the moving speed V (unit: m / s) of the transmitting source S by the reference speed c of the transmitted wave when there is no Doppler effect. 0 (unit: m / s) and is expressed by the following formula.

[0047]

number

[0048] From this equation (1), the frequency of the transmission wave in the direction of angle θ is expressed by the following equation.

[0049]

number

[0050] Therefore, when the reflected wave of the transmitted wave is received by the wave receiving element 21, the angle θ can be identified by the frequency components of the received signal output from the wave receiving element 21. In other words, by extracting a specific frequency component from the received signal, it is possible to obtain a received signal in the direction of the angle θ corresponding to the frequency component. In this embodiment, based on this principle, a received signal at each angular position is obtained.

[0051] FIG. 4 is a diagram showing the results of a simulation in which a surface where frequencies are equal (hereinafter, referred to as an "equal frequency surface") is obtained by simulation.

[0052] In Fig. 4, the units of each axis are meters. The transmitting array is placed so as to extend in the X-axis direction at the midpoint in the Y-axis direction (the position where the distance is zero). The transmitting wave is sent in the Z-axis direction from the midpoint in the Y-axis direction. In other words, the direction from the midpoint in the Y-axis direction toward the Z-axis direction is the front direction.

[0053] 4 shows constant frequency surfaces EP1 to EP5 in a range where the angle θ is on the negative side from the front direction. The constant frequency surfaces EP1, EP2, EP3, EP4, and EP5 are each lower than the frequency f0 in the front direction. In terms of frequency magnitude, the constant frequency surfaces EP1, EP2, EP3, EP4, and EP5 have a relationship of EP1>EP2>EP3>EP4>EP5.

[0054] For convenience, five constant-frequency surfaces EP1 to EP5 are shown in Fig. 4, but many constant-frequency surfaces exist between these constant-frequency surfaces EP1 to EP5. For example, the frequency in the gap between the constant-frequency surfaces EP1 and EP2 transitions continuously from the frequency of the constant-frequency surface EP1 to the frequency of the constant-frequency surface EP2. By folding back the constant-frequency surfaces EP1 to EP5 in Fig. 4 symmetrically with respect to the YZ plane, constant-frequency surfaces are formed in the range on the positive side from the front direction.

[0055] FIG. 5 is a diagram showing a schematic configuration example of a wave transmitting and receiving system.

[0056] In the example of Fig. 5, the transmitting array 10 and the receiving array 20 having the configuration shown in Fig. 2(a) are used. Alternatively, the transmitting array 10 and the receiving array 20 having the configuration shown in Fig. 2(b) may be used.

[0057] By driving the wave transmitting elements 11 in the wave transmitting array 10 in order from the start wave transmitting element 11a to the end wave transmitting element 11b as described above, a transmission beam TB1 is formed in front of the wave transmitting array 10 (positive direction of the Z axis).

[0058] That is, when a transmission signal is supplied to the transmitting element 11, the transmitting element 11 transmits a transmission wave with a relatively wide directivity. When a transmission signal is supplied to the transmitting elements 11 in the transmitting array 10 in order from the start transmitting element 11a to the end transmitting element 11b, the region where all the transmission waves transmitted from each transmitting element 11 overlap is the region of the transmission beam TB1. In this region, as described with reference to FIG. 4, many equal frequency surfaces are generated.

[0059] By performing phase control (beamforming) on ​​the reception signals output from each receiving element 21, a narrow reception beam RB1 is formed in the circumferential direction centered on the X-axis. This allows the reception signals in the area where the reception beam RB1 and the transmission beam TB1 intersect to be extracted. By rotating the reception beam RB1 in the θ2 direction centered on the X-axis through the above-mentioned phase control, the reception signals at each rotation position are extracted. The rotation position of the reception beam RB1 can determine the arrival direction in the Y-axis direction of the reflected wave, which is the transmission wave reflected by the target. In addition, the frequency of the reception signal can determine the iso-frequency surface (see FIG. 4) on which the reflected wave occurs.

[0060] Therefore, among the received signals extracted by the receiving beam RB1, the received signals of the frequency corresponding to each iso-frequency surface are extracted, and the intensity of the extracted received signals on each iso-frequency surface is plotted on each iso-frequency surface, thereby obtaining the distribution of the intensity data of the received signals in the range where the receiving beam RB1 and the transmitting beam TB1 intersect. Then, by rotating the receiving beam RB1 within the detection range in the Y-axis direction and obtaining the distribution of the intensity data at each rotation position, it is possible to obtain the intensity data (volume data) distributed three-dimensionally in the entire detection range in the Y-axis direction and the X-axis direction. By imaging this intensity data (volume data), it is possible to obtain an image showing the state of the target in the detection range.

[0061] The above-mentioned transducer 30 is installed, for example, so that the Y-axis direction in Fig. 5 is horizontal. In this case, the transducer 30 is installed so that the X-axis direction in Fig. 5 is tilted at a predetermined angle with respect to the vertical direction so that the transmission beam TB1 is directed toward the seabed 3. This allows intensity data (volume data) that is three-dimensionally distributed in the detection range in the horizontal and vertical directions to be acquired.

[0062] FIG. 6 is a block diagram showing the configuration of the target detection device 1. As shown in FIG.

[0063] The target detection device 1 includes a control unit 101, a storage unit 102, a transmission signal generation unit 103, a switch 104, a reception processing unit 105, a reception signal processing unit 106, a display unit 107, and an input unit 108.

[0064] The control unit 101 includes an arithmetic processing circuit such as a CPU (Central Processing Unit) and controls each unit according to a program stored in the storage unit 102. The control unit 101 may be configured with an integrated circuit such as an FPGA (Field-Programmable Gate Array). The storage unit 102 includes a storage medium such as a ROM (Read Only Memory) or a RAM (Random Access Memory) and stores the above-mentioned program. The storage unit 102 is also used as a work area when the control unit 101 controls the device.

[0065] The transmission signal generating unit 103 generates a transmission signal in response to control from the control unit 101. The switch 104 supplies transmission signals to the multiple transmitting elements 11 included in the transmitting array 10 in order from the start transmitting element 11a to the end transmitting element 11b in response to control from the control unit 101. As a result, a transmission beam TB1 shown in Fig. 5 is formed, and the above-mentioned iso-frequency surface (see Fig. 4) is formed in this transmission beam TB1. The switch 104 is, for example, configured by a demultiplexer.

[0066] The reception processing unit 105 is connected to each of the multiple receiving elements 21 included in the receiving array 20. The reception processing unit 105 performs processing such as removing unnecessary bands from the received signals input from each receiving element 21, amplifying the received signals to a level suitable for AD conversion, and removing signal components in a band equal to or greater than half the sampling period of the AD conversion. Furthermore, the reception processing unit 105 converts the processed received signals for each receiving element 21 into digital signals at a predetermined sampling period and outputs the digital signals to the received signal processing unit 106.

[0067] The received signal processing unit 106 processes the received signal for each wave receiving element 21 input from the reception processing unit 105, and calculates intensity data (volume data) of the received signal distributed three-dimensionally in the detection range. The calculation process of the volume data is as described with reference to Figures 4 and 5. The received signal processing unit 106, together with the control unit 101, may be configured as a single integrated circuit (such as an FPGA).

[0068] The control unit 101 processes the intensity data (volume data) input from the received signal processing unit 106, and generates image data that visualizes the state of the target in the detection range. The control unit 101 outputs the generated image data to the display unit 107. The display unit 107 is composed of a monitor or the like, and displays a detection image corresponding to the image data input from the control unit 101. The input unit 108 is a user interface, and includes input means such as a trackball, and outputs input information to the control unit 101. The input unit 108 may be a transparent touch pad superimposed on the display unit 107.

[0069] In the target detection device 1 having the above configuration, the range of angle θ (range of angle θ1 in FIG. 5) in which a target can be searched is limited to a band specific to the device. Such band limitation is based on, for example, the operable bands of the transmitting element 11 and the receiving element 21. For example, if the frequency band in which the receiving element 21 can receive a reflected wave and output a received signal is 400 to 660 kHz, the above formula (2) shows that the angle range corresponding to this frequency band is the range in which the frequency of the transmitted wave can be changed. For this reason, when it is necessary to adjust the searchable angle range, it is necessary to adjust the band specific to the device. However, this adjustment is not easy to perform because it requires a change in hardware.

[0070] In view of such problems, this embodiment employs a configuration that allows the range of angle θ that can be searched for in a finite frequency band to be easily adjusted. This configuration will be described below.

[0071] First, the relationship between the frequency band of the transmission wave and the angle θ in FIG. 3 will be described.

[0072] From the above formula (2), it can be seen that the frequency distribution in the transmission beam TB1 changes by changing the moving speed V of the transmission source S. Therefore, by changing the time for supplying a transmission signal to the multiple transmitting elements 11 included in the transmitting array 10 in order from the start transmitting element 11a to the end transmitting element 11b, that is, the sweep time of the switch 104, it is possible to change the frequency distribution in the transmission beam TB1.

[0073] 7 to 9 are graphs showing the relationship between the frequency of the transmission wave and the angle θ of the sweep direction at which each frequency occurs when the sweep time is changed.

[0074] These graphs are based on a simulation. The simulation conditions are as follows:

[0075] ·Reference speed c 0 =1500m / s - Transmission signal frequency f0 = 500kHz Number of transmitting elements = 128 Transmitting element pitch = 0.45λ (λ is the wavelength of the transmitting signal) Sampling frequency = 40000kHz Number of observation points = 181 (pitch 1°, start angle -90°)

[0076] 7 to 9, the horizontal axis is the frequency included in the transmission beam TB1, and the vertical axis is the angle θ corresponding to each frequency. The amplitude of the frequency spectrum at each frequency is indicated by the color scale on the right. The sweep time is indicated as a pulse width in the upper left corner of the graph.

[0077] 7 to 9, a transmission signal was simultaneously supplied to three adjacent wave transmitting elements 11. That is, if the start wave transmitting element 11a is the first wave transmitting element 11, a transmission signal was simultaneously supplied to the first to third wave transmitting elements 11, and then a transmission signal was supplied to the second to fourth wave transmitting elements 11. Thereafter, the three wave transmitting elements 11 to which the transmission signal was to be supplied were shifted by one element at a time, and the transmission signal was simultaneously supplied to the three wave transmitting elements 11, and the same process was repeated until the three wave transmitting elements 11 reached the end wave transmitting element 11b.

[0078] In this way, by simultaneously supplying the transmission signal to the three target wave transmitting elements 11 while shifting the three wave transmitting elements 11 one by one, the effect of noise (spurious) on each frequency component of the transmission beam TB1 can be suppressed and the transmission power can be increased, compared to the case where the transmission signal is supplied to each wave transmitting element 11 in sequence. However, on the other hand, the directivity in the sweep direction (movement direction D1 of the transmission source S) of the transmission waves transmitted from the three wave transmitting elements 11 becomes narrower than the directivity in the sweep direction of the transmission wave transmitted from one wave transmitting element 11. For this reason, when widening the directivity of the transmission wave in the sweep direction, it is preferable to supply the transmission signal to each element in sequence from the start wave transmitting element 11a to the end wave transmitting element 11b.

[0079] Figure 7 shows the relationship between frequency and angle θ when the sweep time (pulse width) is 0.258 ms. In this case, if the finite frequency band of the device is 400 to 660 kHz, the range (angle range) Δθa of the searchable angle θ is approximately -34° to +33°.

[0080] Figure 8 shows the relationship between frequency and angle θ when the sweep time (pulse width) is 0.13 ms. In this case, if the finite frequency band of the device is 400 to 660 kHz, the range of angle θ that can be searched (angle range) Δθb is about -16° to +16°.

[0081] 9 shows the relationship between the frequency and the angle θ when the sweep time (pulse width) is 0.39 ms. In this case, if the finite frequency band of the device is 400 to 660 kHz, the range (angle range) Δθc of the angle θ that can be searched is about -66° to +52°.

[0082] From the verification results of Figures 7 to 9, it can be seen that the range of angles θ that can be searched can be changed by changing the sweep time (pulse width). The longer the sweep time (pulse width), the wider the range of angles θ that can be searched in the finite frequency band of the device. Also, the shorter the sweep time (pulse width), the narrower the range of angles θ that can be searched in the finite frequency band of the device.

[0083] On the other hand, the longer the sweep time (pulse width), the worse the distance resolution for target detection. For example, when the sweep time (pulse width) is 0.258 ms as shown in Figure 7, the distance resolution is about 193.5 mm. In contrast, when the sweep time (pulse width) is 0.13 ms as shown in Figure 8, the distance resolution is about 97.5 mm, and when the sweep time (pulse width) is 0.39 ms as shown in Figure 9, the distance resolution is about 292.5 mm.

[0084] In this way, there is a trade-off between the searchable angle range and the distance resolution. Therefore, it is sufficient if the sweep time can be changed appropriately depending on whether the searchable angle range or the distance resolution is given priority by the user. This makes it possible to easily detect targets according to the user's requirements.

[0085] Moreover, by changing the frequency f0 of the transmission signal, which is one of the parameters in the above formula (2), the central angle of the range of angles θ that can be searched can be further changed.

[0086] 10 to 12 are graphs showing the relationship between the frequency of the transmission wave and the angle θ of the sweep direction at which each frequency occurs when the frequency f0 of the transmission signal is changed.

[0087] Fig. 10 is a graph in which the frequency range of 300 to 700 is extracted from the graph of Fig. 8. The conditions for the simulation of Fig. 10 are the same as those of Fig. 8. In this case, the central angle of the range of searchable angles θ is 0°, which is the angle corresponding to 500 kHz, which is the frequency f0 of the transmission signal.

[0088] FIG. 11 is a graph in which the frequency f0 of the transmission signal is changed to 600 kHz. The vertical and horizontal axes are the same as in FIG. 10. Here, the sweep time (pulse width) is slightly adjusted from that in FIG. 10 in order to suppress noise. The other simulation conditions are the same as in FIG. 10. In this case, the central angle of the range of the searchable angle θ is about -13°, which corresponds to 500 kHz on the horizontal axis. In this case, the range of the searchable angle θ is slightly wider than in FIG. 10.

[0089] FIG. 12 is a graph in which the frequency f0 of the transmission signal is changed to 400 kHz. The vertical and horizontal axes are the same as in FIG. 10. Here, the sweep time (pulse width) is slightly adjusted from that in FIG. 10 in order to suppress noise. The other simulation conditions are the same as in FIG. 10. In this case, the central angle of the range of the searchable angle θ is about +12°, which corresponds to 500 kHz on the horizontal axis. In this case, the range of the searchable angle θ is slightly narrower than in FIG. 10.

[0090] As shown in Figures 10 to 12, the central angle of the range of searchable angles θ can be further changed by changing the frequency f0 of the transmission signal. Therefore, in order to enable detection of the angle range desired by the user, it is sufficient to appropriately change the frequency f0 of the transmission signal. This makes it possible to more effectively detect targets according to the user's request.

[0091] 13 to 15 are graphs showing the relationship between the frequency and the angle θ when a transmission signal is supplied to each element in sequence from the start wave transmitting element 11a to the end wave transmitting element 11b.

[0092] These graphs, like the graphs in Figures 7 to 9, are based on simulations. The simulation conditions are the same as those in Figures 7 to 9. The graphs in Figures 13 to 15 differ from Figures 7 to 9 in that a transmission signal is supplied to each of the multiple transmitting elements 11 included in the transmitting array 10 in sequence, from the start transmitting element 11a to the end transmitting element 11b.

[0093] Fig. 13 shows a graph in which the sweep time (pulse width) is 0.258 ms. This sweep time corresponds to the case of Fig. 7. In the graph of Fig. 13, the width of the waveform is larger than that of Fig. 7 due to the influence of noise (spurious). However, the range Δθa of the searchable angle θ is the same as that of Fig. 7.

[0094] Fig. 14 shows a graph in the case where the sweep time (pulse width) is 0.13 ms. This sweep time corresponds to the case of Fig. 8. In the graph of Fig. 14, the width of the waveform is larger than that in Fig. 8 due to the influence of noise (spurious). However, the range Δθb of the searchable angle θ is the same as in Fig. 8.

[0095] Figure 15 shows a graph in which the sweep time (pulse width) is 0.39 ms. This sweep time corresponds to the case of Figure 9. Of the three graphs in Figure 15, the left graph has a waveform caused by noise (spurious) on its side. However, the range Δθc of the searchable angle θ is the same as that of Figure 9.

[0096] In this way, even when a transmission signal is supplied to each element in sequence, the range of the searchable angle θ can be changed by changing the sweep time (pulse width). In this case, as in the cases of Figs. 7 to 9, there is a trade-off between the searchable angle θ and the distance resolution. Therefore, in this case too, it is sufficient to change the sweep time appropriately depending on whether the user prioritizes the searchable angle range or the distance resolution. This makes it possible to easily detect targets according to the user's request.

[0097] As described above, in the cases of Figures 13 to 15, the directivity of the transmission wave in the sweep direction can be broadened compared to the case in which a transmission signal is simultaneously supplied to three wave transmitting elements 11 as in Figures 7 to 9. Therefore, when broadening the directivity of the transmission wave in the sweep direction, it is preferable to supply a transmission signal to each element in sequence from the start wave transmitting element 11a to the end wave transmitting element 11b as in Figures 13 to 15.

[0098] 16 to 18 are graphs each showing the relationship between the frequency of the transmission wave and the angle θ when the frequency f0 of the transmission signal is changed.

[0099] Fig. 16 is a graph in which the frequency range of 300 to 700 is extracted from the graph of Fig. 14. The conditions of Fig. 16 are the same as those of Fig. 14. In this case, the central angle of the range of searchable angle θ is 0°, which is the angle corresponding to 500 kHz, which is the frequency f0 of the transmission signal.

[0100] FIG. 17 is a graph in which the frequency f0 of the transmission signal is changed to 600 kHz. The vertical and horizontal axes are the same as in FIG. 16. Here, the sweep time (pulse width) is slightly adjusted from that in FIG. 16 in order to suppress noise. The other simulation conditions are the same as in FIG. 16. In this case, the central angle of the range of the searchable angle θ is about -13°, which corresponds to 500 kHz on the horizontal axis. In this case, the range of the searchable angle θ is slightly wider than in FIG. 16.

[0101] FIG. 18 is a graph in which the frequency f0 of the transmission signal is changed to 400 kHz. The vertical and horizontal axes are the same as in FIG. 16. Here, the sweep time (pulse width) is slightly adjusted from that in FIG. 16 in order to suppress noise. The other simulation conditions are the same as in FIG. 16. In this case, the central angle of the range of the searchable angle θ is about +12°, which corresponds to 500 kHz on the horizontal axis. In this case, the range of the searchable angle θ is slightly narrower than in FIG. 16.

[0102] As shown in Figures 16 to 18, even when a transmission signal is supplied to each transmitting element 11 in turn, the central angle of the range of searchable angles θ can be changed by changing the frequency f0 of the transmission signal. Therefore, in this case as well, it is sufficient to change the frequency f0 of the transmission signal as appropriate to enable detection of the angle range desired by the user. This makes it possible to more effectively detect targets according to the user's request.

[0103] FIG. 19 is a flowchart showing the display process of the echo image.

[0104] When the operation of the target detection device 1 starts, the control unit 101 sets the range (sweep time) of the angle θ of the transmission beam TB1 in the sweep direction and the central angle (frequency f0 of the transmission signal) to their initial values ​​(S101). Then, the control unit 101 transmits the transmission wave based on the set initial value. Specifically, the control unit 101 controls the transmission signal generation unit 103 and the switch 104 so that the transmission signal is supplied to the multiple wave transmitting elements 11 included in the wave transmitting array 10 in order from the start wave transmitting element 11a to the end wave transmitting element 11b (S102).

[0105] Here, the transmission signal may be supplied simultaneously to adjacent wave transmitting elements 11 as in the cases of FIGS. 7 to 9, or may be supplied sequentially to each wave transmitting element 11 as in the cases of FIGS.

[0106] In response to the transmission of the transmission wave in step S102, the control unit 101 causes the reception processing unit 105 and the reception signal processing unit 106 to process the reception signals output from the multiple reception elements 21 included in the reception array 20, and acquires intensity data (volume data) distributed in the detection range (S103). Then, the control unit 101 updates the echo image displayed on the display unit 107 with the acquired intensity data (volume data) (S104).

[0107] In parallel with the processing of steps S102 to S103, the control unit 101 accepts input from the user regarding changes to the range of angle θ (sweep time) and central angle (frequency f0 of the transmission signal) of the transmission beam TB1 in the sweep direction. When the processing of one sequence of steps S102 to S103 is completed, the control unit 101 determines whether or not the user has input to change the angle range (S106) or the central angle (S108).

[0108] If neither of these has been input (S106: NO, S108: NO), the control unit 101 returns the process to step S102 and performs the process of the next sequence.

[0109] On the other hand, if an input is made to change the angle range (S106: YES), the control unit 101 changes the sweep time used in the process to a sweep time corresponding to the input angle range (S107). If an input is made to change the central angle (S108: YES), the control unit 101 changes the frequency of the transmission signal to a frequency corresponding to the input central angle (S108). Then, the control unit 101 returns the process to step S102 and performs the process of the next sequence with the newly set angle range or central angle.

[0110] In this manner, the control unit 101 repeatedly executes the processes of steps S102 to S104 and S106 to S109 until the operation of the target detection device 1 is completed (S105: NO). When the angle range or central angle is changed in the processes of steps S106 to S109, the echo image displayed on the display unit 107 is updated to an image corresponding to the changed angle range or central angle. Thereafter, when the operation of the target detection device 1 is completed (S105: YES), the control unit 101 terminates the process of FIG. 19.

[0111] In the process of Fig. 19, the initial values ​​of step S101 may be, for example, a sweep time (0.258 ms in Fig. 7) and a transmission signal frequency (500 kHz in Fig. 7) in which the angle range is around ±35° and the central angle is around 0° as shown in Fig. 7. Alternatively, the initial values ​​of step S101 may be a sweep time and a transmission signal frequency corresponding to the angle range and central angle that were set when the target detection device 1 ended its previous operation.

[0112] 20(a) and 20(b) are diagrams showing examples of the configuration of a reception screen 200 for receiving a change in the angle range (sweep time).

[0113] These reception screens 200 are displayed on the display unit 107 when the user selects a change mode for the angle range via the input unit 108. The user performs input on these reception screens 200 via the input unit 108.

[0114] In the configuration example of FIG. 20(a), three prepared angle ranges can be selected. The reception screen 200 includes three selection buttons 201 to 203 corresponding to the three angle ranges. The selection button 201 is associated with the normal search mode, and an angle range of -35° to +35° is assigned to it. The selection button 202 is associated with the narrow area search mode, and an angle range of -15° to +15° is assigned to it. The selection button 203 is associated with the wide area search mode, and an angle range of -65° to +50° is assigned to it.

[0115] Display 201a to 203a indicating the angle range in each mode are arranged to the right of the three selection buttons 201 to 203. By referring to these displays 201a to 203a, the user can understand the angle ranges assigned to the three selection buttons 201 to 203. The reception screen 200 further includes a confirmation button 204 for confirming the selection of the selection buttons 201 to 203, and a button 205 for returning to the screen.

[0116] When any of the selection buttons 201 to 203 is selected and the confirmation button 204 is operated, the determination in step S106 in FIG. 19 becomes YES. Here, when the selection button 201 is selected, a sweep time corresponding to an angle range of -35° to +35° (for example, 0.258 ms in the example of FIG. 7) is set in step S107 in FIG. 19. When the selection button 202 is selected, a sweep time corresponding to an angle range of -15° to +15° (for example, 0.13 ms in the example of FIG. 8) is set in step S107 in FIG. 19. When the selection button 203 is selected, a sweep time corresponding to an angle range of -65° to +50° (for example, 0.39 ms in the example of FIG. 9) is set in step S107 in FIG. 19.

[0117] In the configuration example of Fig. 20(a), the number of selectable angle ranges is three, but the number of selectable angle ranges is not limited to this. Also, each angle range is an example, and the upper and lower limits of the selectable angle ranges can be changed as appropriate.

[0118] In the configuration example of Fig. 20(b), the angle range (sweep time) can be set arbitrarily. The reception screen 200 includes an up button 211 for increasing the sweep time and a down button 212 for decreasing the sweep time. In response to an operation on the up button 211 or the down button 212, the value of the display item 213 for the sweep time increases or decreases, and accordingly, the value of the display item 214 for the angle range increases or decreases. The reception screen 200 further includes a confirmation button 215 for confirming the sweep time and a button 216 for returning the screen.

[0119] The user operates the up button 211 and the down button 212 until the value of the display item 214 falls within the desired angle range, and then operates the confirm button 215. As a result, the determination in step S106 in Fig. 19 becomes YES. In this case, the sweep time displayed in the display item 213 at the time of the confirm operation is set in step S107 in Fig. 19.

[0120] In the configuration example of Fig. 20(b), for example, a table associating the sweep time displayed in the display item 213 with the angle range displayed in the display item 214 is stored in advance in the storage unit 102 of Fig. 6. In this case, it is not necessary to associate the angle range with all the changeable sweep times, and for example, a predetermined number of pairs of the sweep time and the angle range may be stored in the storage unit 102, and the angle range corresponding to the sweep time other than these pairs may be calculated by an interpolation calculation from the angle range of these pairs. On the other hand, in the configuration example of Fig. 20(a), it is sufficient that the angle range and the sweep time of each mode are stored in the storage unit 102.

[0121] 21(a) and 21(b) are diagrams showing examples of the configuration of a reception screen 300 for receiving a change in the central angle (frequency of a transmission signal).

[0122] These reception screens 300 are displayed on the display unit 107 when the user selects a central angle change mode via the input unit 108. The user performs input on these reception screens 300 via the input unit 108.

[0123] In the configuration example of Fig. 21(a), three prepared central angles can be selected. The reception screen 300 includes three selection buttons 301 to 303 corresponding to the three central angles. The selection button 301 is associated with the front direction, and 0° is assigned as the central angle. The selection button 302 is associated with the negative direction, and -10° is assigned as the central angle. The selection button 303 is associated with the positive direction, and +10° is assigned as the central angle.

[0124] Display 301a to 303a indicating the angular direction at each central angle are arranged to the right of the three selection buttons 301 to 303. By referring to these displays 301a to 303a, the user can understand the direction of the central angle assigned to the three selection buttons 301 to 303. The reception screen 300 further includes a confirmation button 304 for confirming the selection of the selection buttons 301 to 303, and a button 305 for returning to the screen.

[0125] When any of the selection buttons 301 to 303 is selected and the confirmation button 304 is operated, the determination in step S108 in FIG. 19 becomes YES. Here, when the selection button 301 is selected, the frequency of the transmission signal corresponding to the central angle of 0° (for example, 500 kHz in the example of FIG. 10) is set in step S109 in FIG. 19. When the selection button 302 is selected, the frequency of the transmission signal corresponding to the central angle of -10° (for example, 600 kHz in the example of FIG. 11) is set in step S109 in FIG. 19. When the selection button 303 is selected, the frequency of the transmission signal corresponding to the central angle of +10° (for example, 400 kHz in the example of FIG. 12) is set in step S109 in FIG. 19.

[0126] In the configuration example of Fig. 21(a), there are three selectable central angles, but the number of selectable central angles is not limited to this. Also, the directions of the respective central angles are merely examples, and the directions of the selectable central angles can be changed as appropriate.

[0127] In the configuration example of Fig. 21(b), the central angle (frequency of the transmission signal) can be set arbitrarily. The reception screen 300 includes an up button 311 for increasing the frequency of the transmission signal (transmission frequency) and a down button 312 for decreasing the transmission frequency. Depending on the operation of the up button 311 or the down button 312, the value of the display item 313 of the transmission frequency increases or decreases, and accordingly, the value of the display item 314 of the central angle increases or decreases. The reception screen 300 further includes a confirmation button 315 for confirming the central angle and a button 316 for returning the screen.

[0128] The user operates the up button 311 and the down button 312 until the value of the display item 314 becomes the desired value, and then operates the confirm button 315. As a result, the determination in step S108 in Fig. 19 becomes YES. In this case, the transmission frequency displayed in the display item 313 at the time of the confirm operation is set in step S109 in Fig. 19.

[0129] In the configuration example of Fig. 21(b), for example, a table associating the transmission frequency displayed in the display item 313 with the central angle displayed in the display item 314 is stored in advance in the storage unit 102 of Fig. 6. In this case, it is not necessary to associate the central angle with all the changeable transmission frequencies, and for example, a predetermined number of pairs of transmission frequencies and central angles may be stored in the storage unit 102, and central angles corresponding to transmission frequencies other than these pairs may be calculated by interpolation from the central angles of these pairs. On the other hand, in the configuration example of Fig. 21(a), it is sufficient that the central angle of each direction and the transmission frequency are stored in the storage unit 102.

[0130] In the examples of Figures 11 and 12, the sweep time (pulse width) is also adjusted to suppress noise along with the change in transmission frequency. Therefore, when the transmission frequency is changed by the reception screen 300 of Figure 21(a) or Figure 21(b), the sweep time may be further adjusted to suppress noise.

[0131] Furthermore, when the sweep direction for the multiple transmitting elements 11 included in the transmitting array 10 is a vertically downward direction, if the sign of the central angle is negative, the central angle shifts vertically upward, and if the sign of the central angle is positive, the central angle shifts vertically downward. Therefore, in this case, the notations of the selection buttons 302 and 303 in Fig. 21(a) may be changed to upward and downward, respectively. Similarly, when the sweep direction for the multiple transmitting elements 11 included in the transmitting array 10 is a direction from the port side to the starboard side, the notations of the selection buttons 302 and 303 in Fig. 21(a) may be changed to left and right, respectively.

[0132] <Effects of the embodiment> According to the embodiment, the following effects can be achieved.

[0133] As shown in FIG. 6, the target detection device 1 includes a transmission signal generating unit 103 that generates a transmission signal, a transmitting array 10 having a plurality of transmitting elements 11 that convert the transmission signal into a transmission wave and having at least a start transmitting element 11a and an end transmitting element 11b, a switch 104 that supplies a transmission signal to the plurality of transmitting elements 11 in sequence from the start transmitting element 11a to the end transmitting element 11b, and a control unit 101 that controls the sweep time of the switch 104, which is the time from the supply of the transmission signal to the start transmitting element 11a to the supply of the transmission signal to the end transmitting element 11b.

[0134] According to the target detection device 1 of the first aspect, by changing the sweep time of the switch 104, it is possible to change the searchable angle range (angle θ range Δθa to Δθc) corresponding to the arrangement direction (sweep direction) of the wave transmitting elements 11 in a finite band (here, 400 to 660 kHz) of the device, for example, as shown in Figures 7 to 9 and 13 to 15. Therefore, it is possible to easily adjust the searchable angle range in the finite band of the device.

[0135] 7 to 9 and 13 to 15, the sweep time (pulse width) sets the angle range (angle θ range Δθa to Δθc) in which the transmission wave is transmitted. Here, when the control unit 101 lengthens the sweep time, the angle range widens.

[0136] In this way, by controlling the sweep time, the angle range in which the transmission wave is transmitted can be widened or narrowed, and therefore the angle range in which the search can be performed for target detection can be changed with simple control.

[0137] As shown in Figures 6, 20(a) and 20(b), the target detection device 1 has an input unit 108 (reception screen 200) that is used by a user to input values ​​corresponding to a sweep time or an angle range.

[0138] According to this configuration, the user can set the searchable angle range to a desired angle range.

[0139] As shown in FIGS. 19, 21(a) and 21(b), the control unit 101 controls the frequency of the transmission signal.

[0140] Here, the frequency of the transmission signal is set to the central direction (central angle) of the angle range in which the transmission wave is transmitted, as shown in Figs. 10 to 12 and Figs. 16 to 18.

[0141] In this way, by controlling the frequency of the transmission signal, the center direction of the angular range of the transmission wave can be easily adjusted.

[0142] As shown in FIG. 6, the target detection device 1 includes a receiving array 20 including at least one receiving element 21 that receives a reflected wave generated by reflection of a transmitted wave at a target and converts the reflected wave into a received signal, and a processing circuit (received signal processing unit 106) that extracts frequency components of the received signal and determines the direction of arrival of the reflected wave.

[0143] According to this configuration, a target object existing within the angular range of the transmission wave can be detected from the reception signal output by the wave receiving element 21.

[0144] As shown in FIG. 1, the target detection device 1 is a sonar that detects underwater targets.

[0145] With this configuration, targets present within the underwater detection range can be detected.

[0146] As shown in FIG. 19, the target detection control method executed by the control unit 101 includes a step (S102) of supplying a transmission signal to a plurality of transmitting elements 11 that convert a transmission signal into a transmission wave in sequence from a start transmitting element 11a to a finish transmitting element 11b, and a step (S106, S107) of controlling a sweep time, which is the time from the supply of the transmission signal to the start transmitting element 11a to the supply of the transmission signal to the finish transmitting element 11b.

[0147] According to this control method, the sweep time of the wave transmitting elements 11 is controlled, so that the angle range that can be searched in the finite band of the device can be easily adjusted, as shown in FIGS. 7 to 9 and 13 to 15.

[0148] <Change Example 1> The present invention is not limited to the above-described embodiment, and various modifications of the embodiment of the present invention are possible in addition to the above-described configuration.

[0149] FIG. 22 is a flowchart showing echo image display processing according to the first modification.

[0150] When the operation of the target detection device 1 starts, the control unit 101 sets the angle range (sweep time) of the transmission beam TB1 in the sweep direction to a predetermined value (S111), and sets the central angle (transmission frequency) to a first value (S112). Then, the control unit 101 transmits the transmission wave 1 based on these set values. Specifically, the control unit 101 controls the transmission signal generation unit 103 and the switch 104 so that the transmission signal is supplied to the multiple wave transmitting elements 11 included in the wave transmitting array 10 in order from the start wave transmitting element 11a to the end wave transmitting element 11b (S113).

[0151] Here, the transmission signal may be supplied simultaneously to adjacent wave transmitting elements 11 as in the cases of FIGS. 7 to 9, or may be supplied sequentially to each wave transmitting element 11 as in the cases of FIGS.

[0152] In response to sending the transmission wave in step S113, the control unit 101 causes the reception processing unit 105 and the reception signal processing unit 106 to process the reception signals output from the multiple receiving elements 21 included in the receiving array 20, and acquires intensity data (volume data) distributed in the first detection range (S114).

[0153] Next, the control unit 101 sets the central angle (transmission frequency) to a second value (S115), and transmits the transmission wave based on the set second value. Specifically, the control unit 101 controls the transmission signal generating unit 103 and the switch 104 so that the transmission signal is supplied to the multiple transmitting elements 11 included in the transmitting array 10 in order from the start transmitting element 11a to the end transmitting element 11b (S116). The sweep time at this time is maintained at the set value of step S111.

[0154] In response to the transmission of the transmission wave in step S116, the control unit 101 causes the reception processing unit 105 and the reception signal processing unit 106 to process the reception signals output from the multiple reception elements 21 included in the reception array 20, and acquires intensity data (volume data) distributed in the second detection range (S117). Then, the control unit 101 updates the echo image displayed on the display unit 107 with the intensity data (volume data) acquired in steps S114 and S117 (S118).

[0155] After updating the echo image in this way, the control unit 101 judges whether or not the operation of the target detection device 1 has ended (S119). If the operation of the target detection device 1 has not ended (S119: NO), the control unit 101 returns the process to step S112 and executes the process of the next sequence. The control unit 101 repeatedly executes the processes of steps S112 to S118 until the operation of the target detection device 1 has ended (S119: NO). Thereafter, when the operation of the target detection device 1 has ended (S119: YES), the control unit 101 ends the process of FIG. 22.

[0156] 23(a) and 23(b) are diagrams typically showing examples of setting the central angle in steps S112 and S115 of FIG.

[0157] 23(a) and 23(b), the state of the transmission wave when the transmitting array 10 is viewed from the side is indicated by a dashed line. More specifically, the direction of the central angle set in step S112 is indicated as a first central angle direction CA1, and the direction of the central angle set in step S115 is indicated as a second central angle direction CA2. In addition, the transmission beam formed by the process of step S113 in FIG. 22 and its angular range (angular range of the moving direction D1) are indicated as a first transmission beam TB11 and a first angular range Δθ11, and the transmission beam formed by the process of step S116 in FIG. 22 and its angular range (angular range of the moving direction D1) are indicated as a second transmission beam TB12 and a second angular range Δθ12.

[0158] In the setting example of Fig. 23(a), the first central angle direction CA1 and the second central angle direction CA2 are set so that the lower boundary of the first angle range Δθ11 coincides with the upper boundary of the second angle range Δθ12. That is, the sweep time in step S111 and the transmission frequency in steps S112 and S115 in Fig. 22 are set so that the first angle range Δθ11 and the second angle range Δθ12 have such a relationship. In this setting example, a wide angle range obtained by integrating the first angle range Δθ11 and the second angle range Δθ12 can be set as the searchable angle range.

[0159] In the setting example of Fig. 23(b), the first central angle direction CA1 and the second central angle direction CA2 are set so that the lower boundary of the first angle range Δθ11 and the upper boundary of the second angle range Δθ12 are separated from each other. That is, the sweep time in step S111 and the transmission frequency in steps S112 and S115 in Fig. 22 are set so that the first angle range Δθ11 and the second angle range Δθ12 have such a relationship. In this setting example, the first angle range Δθ11 and the second angle range Δθ12 can each be set as a searchable angle range.

[0160] <Effects of Change Example 1> As shown in Figures 22, 23(a) and 23(b), the control unit 101 sets the frequency of the transmission signal to a first frequency for transmitting the transmission wave in the central direction of the first direction (first central angle direction CA1) at a first timing (steps S112 to S114) (S112), and sets the frequency of the transmission signal to a second frequency different from the first frequency at a second timing (steps S115 to S117) after the first timing in order to transmit the transmission wave in the central direction of a second direction (second central angle direction CA2) different from the first direction (S115).

[0161] As a result, as shown in Figures 23(a) and 23(b), the central directions (first central angle direction CA1, second central angle direction CA2) of the angular range of the transmission wave are different between the first timing and the second timing, so that the searchable angular range can be set to a wide angular range across all of these angular ranges.

[0162] In the process of Fig. 22, two sets of central angle directions and angle ranges are set, but three or more sets of central angle directions and angle ranges may be set. The method of setting each set is not limited to the method of Fig. 23(a) and Fig. 23(b), and a part of the first angle range Δθ11 and a part of the second angle range Δθ12 may overlap. In this case, the echo image may be constructed using only the volume data of one of the angle ranges for the volume data of the overlapping ranges.

[0163] Also in the configuration of the first modified example, the first angle range Δθ11 and the second angle range Δθ12 (respective sweep times) may be set by the user, and the first central angle direction CA1 and the second central angle direction CA2 (respective transmission frequencies) may be set by the user. This can improve the convenience for the user.

[0164] <Change Example 2> FIG. 24 is a diagram showing a method of supplying a transmission signal to the wave transmitting element 11 according to the second modification.

[0165] In the second modification, among the multiple transmitting elements 11 included in the transmitting array 10, the odd-numbered transmitting elements 11 and the even-numbered transmitting elements 11 are separately supplied with transmission signals S11 and S12. The carrier frequencies of the transmission signals S11 and S12 are all constant at frequency f0. The odd-numbered transmitting elements 11 to which the transmission signal S11 is supplied are switched in turn to the moving direction D1 by the switch 104a. The even-numbered transmitting elements 11 to which the transmission signal S12 is supplied are switched in turn to the moving direction D1 by the switch 104b.

[0166] The time during which the transmission signal S11 is supplied to the odd-numbered wave sending elements 11 is the same as the time during which the transmission signal S12 is supplied to the even-numbered wave sending elements 11. However, the time during which the transmission signal S12 is supplied to the even-numbered wave sending elements 11 is delayed by half the time during which the transmission signal S11 is supplied to the odd-numbered wave sending elements 11. In other words, the timing at which the transmission signal S12 is supplied to the even-numbered wave sending elements 11 is delayed by half the time at which the transmission signals S11, S12 are supplied to the wave sending elements 11, relative to the timing at which the transmission signal S11 is supplied to the odd-numbered wave sending elements 11.

[0167] In the second modification as well, the transmission signals S11 and S12 are supplied to the wave transmitting elements 11 in order from the start wave transmitting element 11a to the end wave transmitting element 11b by controlling the switches 104a and 104b as described above.

[0168] At this time, since the transmission signal S12 is supplied to the even-numbered wave sending elements 11 at the switching timing of the odd-numbered wave sending elements 11, the generation of unnecessary frequency components (spurious) due to the switching of the odd-numbered wave sending elements 11 is suppressed. Similarly, since the transmission signal S12 is supplied to the odd-numbered wave sending elements 11 at the switching timing of the even-numbered wave sending elements 11, the generation of unnecessary frequency components (spurious) due to the switching of the even-numbered wave sending elements 11 is suppressed. In the configuration of Fig. 24, the amplitudes of the transmission signals S11, S12 are modulated so as to effectively suppress the generation of such unnecessary frequency components (spurious).

[0169] In the configuration of the modified example 2, as in the above embodiment, the angular range of the transmission beam TB1 in the movement direction D1 (sweep direction) can be changed by changing the sweep time, which is the time for supplying the transmission signals S11, S12 from the start wave-transmitting element 11a to the end wave-transmitting element 11b. Also, in the configuration of the modified example 2, as in the above embodiment, the direction of the central angle of this angular range can be changed by changing the frequency of the transmission signals S11, S12. The configuration of the modified example 1 may be applied to the configuration of the modified example 2.

[0170] 24 shows eight transmitting elements 11, the number of transmitting elements 11 included in the transmitting array 10 is not limited to this. The actual number of transmitting elements 11 may be several stages greater than eight.

[0171] <Other changes> In the above embodiment, the transmission beam TB1 is formed by one sweep in which the transmission signal is supplied to the wave transmitting elements 11 in order from the start wave transmitting element 11a to the end wave transmitting element 11b, but the transmission beam TB1 may be formed by continuously repeating this sweep multiple times. This control also allows the transmission beam TB1 to have a change in frequency in the sweep direction, and the angular range of the transmission beam TB1 can be changed by changing the sweep time (movement speed of the transmission source).

[0172] According to this control, although the frame rate of the echo image decreases due to repeated sweeping, the power of the transmission beam TB1 can be increased. Therefore, the distance range in which the target can be detected can be expanded. In this control, in order to increase the distance resolution, the carrier frequency of the transmission signal may be frequency modulated like a chirp signal, and a matched filter may be arranged in the reception signal processing unit 106.

[0173] In addition, in the verifications of Figures 7 to 12, the destination of the transmission signal was switched in sequence for three consecutive transmitting elements 11, but the destination of the transmission signal may also be switched in sequence for a number of consecutive transmitting elements 11 other than three.

[0174] In addition, in the above embodiment, it was explained that the frequency components of each frequency are extracted from the received signal, and then the signal is separated into signals for each direction by beamforming processing. However, the received signal may first be separated into signals for each direction by beamforming processing, and then the frequency components of each frequency may be extracted from the separated signals for each direction.

[0175] In the above embodiment, as shown in Fig. 2(a) and Fig. 2(b), a plurality of wave receiving elements 21 are provided, but the reflected wave may be received by only one wave receiving element 21. However, in this case, the intensity data of the received signal cannot be divided by direction and mapped on an equal frequency surface, so the situation of the detection range cannot be displayed in a three-dimensional image as in the above embodiment. In this configuration, the direction of the receiving beam (the direction of θ2 in Fig. 5) is fixed. By extracting the frequency components of the received signal from the receiving beam in that direction, the intensity data in each direction in the vertical direction can be obtained. Therefore, by mapping the intensity data in each direction in the vertical direction, a two-dimensional detection image can be displayed.

[0176] In the above-mentioned modified example 2, the transmission signals S11 and S12 are the same signal, but the transmission signals S11 and S12 may be different signals as long as unnecessary frequency components of the transmission waves can be suppressed. The carrier frequency of the transmission signals S11 and S12 does not necessarily have to be constant, and the carrier signal may be frequency modulated like a chirp signal. The transmission signals S11 and S12 may be burst waves.

[0177] Furthermore, the timing for switching the odd-numbered transmitting elements 11 to which the transmission signal S11 is supplied and the timing for switching the even-numbered transmitting elements 11 to which the transmission signal S12 is supplied are not limited to the above-mentioned timings, and may be other timings as long as unnecessary frequency components occurring in the transmission wave are suppressed.

[0178] Furthermore, the configuration of the transmitting array 10 is not limited to that of the above embodiment and modified example 2, and may be other configurations as long as they can cause a change in frequency of the transmitting beam TB1 based on the Doppler effect.

[0179] For example, as in Modification Example 3 shown in Fig. 25(a), two rows of wave sending elements 11, 12 may be arranged so that a wave sending element 12 is positioned on the side of the boundary between two adjacent wave sending elements 11. In this case as well, a transmission signal S11 and a transmission signal S12 are supplied to each of the wave sending elements 11 and wave sending elements 12 in order starting from the start wave sending elements 11a, 12a at the same timing as in the case of Fig. 24. This makes it possible to suppress unnecessary frequency components occurring in the transmission wave, as in Modification Example 2 above.

[0180] Also, as in Modification Example 4 shown in FIG. 25(b), a configuration may be adopted in which a plurality of wave transmitting elements 11 are grouped into a plurality of groups, and the supply destination of the transmission signal S1 is switched between the groups by the switch 104. With this configuration as well, the wave transmitting source can be moved in the moving direction D1, so that a change in frequency based on the Doppler effect can be caused in the transmission beam TB1. Furthermore, since the transmission wave is transmitted for each group, the output of the transmission wave can be increased. The number of grouped wave transmitting elements 11 is not limited to two, and may be three or more.

[0181] The number of transmitting elements 11 is not limited to the number shown in the above embodiment and modified examples, and may be any other number as long as it is plural. In the above embodiment, the transmitting array 10 and the receiving array 20 are arranged perpendicular to each other, but the transmitting array 10 and the receiving array 20 may be arranged at an angle slightly deviated from the perpendicular.

[0182] Furthermore, in the above embodiment, the target detection device 1 is a sonar installed on the ship 2, but the target detection device 1 may be a radar for detecting targets existing in space. In this case, for example, a transducer is installed on the side wall of the wheelhouse 2a. The transducer includes a transmitting array 10 and a receiving array 20. The transmitting array 10 transmits transmission waves into the air by the above-mentioned processing. Here, radio waves are transmitted as the transmission waves. The circuit configuration is installed in the wheelhouse 2a, similar to the case of a sonar.

[0183] According to this configuration, a detection image showing the situation of obstacles, flocks of birds, etc. is displayed on the display unit 107. This allows the user to grasp the situation in the air. Note that a transducer may be installed on each of the front, rear, left and right sides of the wheelhouse 2a. In this case, the configuration of the transmission system and reception system of FIG. 6 is prepared for each transducer. This allows the display unit 107 to display a detection image of the space all around the ship.

[0184] Furthermore, the target detection device 1 may be installed on a moving body other than the ship 2, or the target detection device 1 may be installed on a structure other than a moving body, such as a buoy.

[0185] In addition, the embodiments of the present invention can be modified in various ways as appropriate within the scope of the claims. [Explanation of symbols]

[0186] 1 Target detection device 10 Transmitting Array 11, 12 Transmitting element 11a, 12a Starting transmitting element 11b End transmitting element 20 Receiving Array 21 Receiving element 101 Control section 102 Storage section 103 Transmission signal generator 104 Switch 108 Input section 200, 300 Reception screen Δθa~Δθc, Δθ11, Δθ12 angle range

Claims

1. a transmission signal generating unit that generates a transmission signal; a wave transmitting array having a plurality of transmitting elements for converting the transmission signal into a transmission wave, the transmitting array having at least a start transmitting element and an end transmitting element; a switch for supplying the transmission signal to the plurality of wave transmitting elements in sequence from the start wave transmitting element to the end wave transmitting element; A control unit that controls a sweep time of the switch, which is a time from the supply of the transmission signal to the start wave-transmitting element to the supply of the transmission signal to the end wave-transmitting element. A target detection device comprising:

2. The target detection device according to claim 1, The sweep time sets an angular range over which the transmission wave is transmitted. A target detection device comprising:

3. The target detection device according to claim 2, When the control unit increases the sweep time, the angle range increases. A target detection device comprising:

4. The target detection device according to claim 2, and an input unit used by a user to input a value corresponding to the sweep time or the angle range. The target detection device is characterized by the above.

5. The target detection device according to claim 1, The control unit further controls a frequency of the transmission signal. A target detection device comprising:

6. The target detection device according to claim 5, The frequency of the transmission signal determines the center direction of the angular range in which the transmission wave is transmitted. A target detection device comprising:

7. 7. The target detection device according to claim 6, At a first timing, the control unit sets the frequency of the transmission signal to a first frequency for transmitting the transmission wave in the center direction of a first direction; At a second timing after the first timing, the control unit sets the frequency of the transmission signal to a second frequency different from the first frequency in order to transmit the transmission wave in the central direction of a second direction different from the first direction. A target detection device comprising:

8. The target detection device according to any one of claims 1 to 7, a wave receiving array including at least one wave receiving element that receives a reflected wave generated by reflection of the transmission wave at a target and converts the reflected wave into a received signal; A processing circuit that extracts a frequency component of the received signal and determines the direction of arrival of the reflected wave. The target detection device is characterized by the above.

9. The target detection device according to claim 1, The target detection device is a sonar that detects underwater targets. The target detection device is characterized by the above.

10. supplying a transmission signal to a plurality of transmitting elements that convert a transmission signal into a transmission wave in sequence from a start transmitting element to an end transmitting element; Controlling a sweep time, which is a time from supplying the transmission signal to the start wave-transmitting element to supplying the transmission signal to the end wave-transmitting element. A target detection method comprising:

11. A control unit of the target detection device A function of supplying a transmission signal to a plurality of transmitting elements that convert a transmission signal into a transmission wave in sequence from a start transmitting element to an end transmitting element; a program for controlling a sweep time, which is the time from the supply of the transmission signal to the start wave-transmitting element to the supply of the transmission signal to the end wave-transmitting element.

Images