Object Detection Device and Object Detection Method

Abstract

The problem lies in providing a target detection device and a target detection method that can quickly detect a target object with a simple configuration. The solution lies in that the target detection device (1) includes: a first transmission signal generation unit (111) that generates a first transmission signal; a first transmission wave array (11) that has a plurality of first transmission wave elements (11a) that convert the first transmission signal into a transmission wave; a first signal switching unit (113) that supplies the first transmission signal to one first transmission wave element (11a) within the first transmission wave array (11); and a control unit (101) that controls the first signal switching unit (113) to switch the first transmission wave element (11a) to which the first transmission signal is supplied from the first element to the second element at a first timing.

Description

Technical Field

[0001] The present invention relates to a target detection device and a target detection method that transmit a transmission wave and detect a target based on a reflected wave thereof. Background Art

[0002] Conventionally, a target detection device that transmits a transmission wave and detects a target based on a reflected wave thereof has been known. In such a target detection device, for example, a transmission / reception wave array in which elements for transmitting and receiving waves are two-dimensionally arranged is used to detect a target. For example, a transmission wave is transmitted using an element at the center of the transmission / reception wave array, and a reflected wave is received using all the elements of the transmission / reception wave array. When receiving a wave, by performing phase control for all the elements, reception beams are formed in various directions, and reception signals are generated for each direction. By processing the reception signals in each direction, a target is detected for each direction.

[0003] Such a target detection device is disclosed in Patent Document 1.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: US Patent No. 7355924 Specification Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] In the target detection device configured as described above, the number of elements in the transmission / reception wave array is large, and the number of transmission channels and reception channels is also large. Therefore, the configuration of the target detection device is complicated, and it is difficult to reduce costs.

[0009] In view of this problem, an object of the present invention is to provide a target detection device and a target detection method that can quickly detect a target with a simple configuration.

[0010] Means for Solving the Problems

[0011] A first aspect of the present invention relates to a target detection device. The target detection device according to this aspect includes: a first transmission signal generation unit that generates a first transmission signal; a first transmission wave array having a plurality of first transmission wave elements that convert the first transmission signal into a transmission wave; a first signal switching unit that supplies the first transmission signal to one of the first transmission wave elements in the first transmission wave array; and a control unit that controls the first signal switching unit to switch the first transmission wave element supplied with the first transmission signal from a first element to a second element at a first timing.

[0012] In the target detection device according to the first method, the first transmission wave element to which the first transmission signal is supplied is switched from the first element to the second element within the first transmission wave array, so that the transmission wave source of the transmission wave moves in the arrangement direction of the first transmission wave elements. As a result, the frequency of the transmission beam changes corresponding to the direction of the transmission wave due to the Doppler effect, and a plurality of equal-frequency surfaces (surfaces with equal frequencies) are formed in the transmission beam. Therefore, by extracting the frequency components corresponding to the respective equal-frequency surfaces from the received signals generated by the receiving wave elements, it is possible to obtain the received signals based on the reflected waves from the respective equal-frequency surfaces. In this way, in the target detection device according to the first method, by moving the transmission wave source by switching the first transmission wave element to which the first transmission signal is supplied within the first transmission wave array, it is possible to simultaneously generate the received signals corresponding to all the equal-frequency surfaces of the observation target. As a result, it is possible to quickly detect the target with a simple configuration.

[0013] The target detection device according to the first method may be configured such that the second element is adjacent to the first element within the first transmission wave array.

[0014] Alternatively, it may be configured that when there are three or more first transmission wave elements included in the first transmission wave array, the control unit controls the first signal switching unit to switch the first transmission wave element to which the first transmission signal is supplied from the second element to the third element adjacent to the second element at the second timing after the first timing.

[0015] According to this configuration, the first transmission signal is sequentially supplied to the adjacent first transmission wave elements, so that the transmission wave source of the transmission wave can be finely moved in the arrangement direction of the first transmission wave elements. As a result, the change in frequency caused by the Doppler effect can be smoothly generated.

[0016] In the target detection device according to the first method, the carrier wave of the first transmission signal may be set to a single frequency.

[0017] Alternatively, in the target detection device according to the first method, the carrier wave of the first transmission signal may also be a modulated signal.

[0018] The target detection device according to the first method may be configured such that the plurality of first transmission wave elements are grouped into a plurality of groups, a plurality of the first transmission wave elements are connected in each group, the first signal switching unit has a configuration for supplying the first transmission signal to one of the groups within the first transmission wave array, and the control unit controls the first signal switching unit to switch the group to which the first transmission signal is supplied from the first group to the second group at the first timing.

[0019] According to this configuration, the transmission wave is transmitted in groups, so the output of the transmission wave can be increased. In addition, the supply of the transmission signal is switched between groups, so the transmission wave source of the transmission wave can be moved. Thus, the Doppler effect can be used to cause a change in the frequency of the transmission beam.

[0020] The target detection device according to the first mode may further include: a second transmission signal generation unit that generates a second transmission signal; a second transmission wave array having a plurality of second transmission wave elements that convert the second transmission signal into a transmission wave; and a second signal switching unit that supplies the second transmission signal to one of the second transmission wave elements in the second transmission wave array. In this configuration, it can be configured that the control unit further controls the second signal switching unit to switch the second transmission wave element to which the second transmission signal is supplied from the first element to the second element at a third timing after the first timing.

[0021] According to this configuration, by adjusting the first transmission signal and the second transmission signal, it is possible to suppress the overlapping of unnecessary frequency components on the transmission wave. Thus, processing can be performed with higher accuracy based on the received signal.

[0022] In this configuration, it is preferably that the second element in the second transmission wave array is adjacent to the first element, and the first element of the first transmission wave array is adjacent to the first element of the second transmission wave array.

[0023] According to this configuration, during the period when the transmission wave source of the transmission wave based on the first transmission signal moves from the first element in the first transmission wave array to the second element, a transmission wave based on the second transmission signal is transmitted from the first element in the second transmission wave array at a position between the first element and the second element. Thus, it is easy to maintain the continuity of the transmission wave. Thus, the overlapping of unnecessary frequency components on the transmission wave can be suppressed.

[0024] In the target detection device according to the first mode, the carrier wave of the second transmission signal may be set to a single frequency.

[0025] In addition, in the target detection device according to the first mode, the carrier wave of the second transmission signal may also be a modulated signal.

[0026] In the target detection device according to the first mode, it can be configured that the first transmission signal generation unit modulates the amplitude of the first transmission signal, and the second transmission signal generation unit modulates the amplitude of the second transmission signal.

[0027] In this way, by modulating the amplitudes of the first transmission signal and the second transmission signal, it is possible to more effectively suppress the overlapping of useless frequency components on the transmitted wave. As a result, the quality of the received signal corresponding to each equiphase plane can be improved.

[0028] In the target detection device according to the first method, the frequency of the carrier wave of the second transmission signal may be set to be the same as the frequency of the carrier wave of the first transmission signal.

[0029] The target detection device according to the first method may further include: a receiving wave array including at least one receiving wave element that receives a reflected wave generated by reflecting the transmitted wave on a target and converts the reflected wave into a received signal.

[0030] In this case, the target detection device may further include a received signal processing unit that processes the received signal, and the received signal processing unit is configured to extract, based on the frequency components of the received signal, a received signal based on the reflected wave from the equiphase plane corresponding to the frequency.

[0031] As described above, by switching the transmission wave element that becomes the transmission wave source in the arrangement direction of the transmission wave elements, the transmission wave source is moved, so that a plurality of equiphase planes (planes with equal frequencies) where the transmission beams overlap are formed. Therefore, based on the frequency components of the received signal, the equiphase plane corresponding to the frequency can be specified, and the received signal based on the reflected wave from the equiphase plane, that is, the equiphase received signal, can be extracted. Thus, according to the above configuration, through the processing of the received signal processing unit, the equiphase received signal corresponding to each equiphase plane can be obtained smoothly.

[0032] In this configuration, the received signal processing unit may be configured to obtain the equiphase received signal of the equiphase plane corresponding to each frequency by extracting a plurality of frequency components extracted at different frequencies from the received signal.

[0033] Alternatively, in this configuration, the received signal processing unit may be configured to calculate the spectrum of the received signal and obtain the equiphase received signal of the equiphase plane corresponding to each frequency based on the spectrum.

[0034] In the target detection device according to the first method, it may be configured that the receiving wave array includes a plurality of receiving wave elements, and the received signal processing unit performs beamforming based on the received signals generated by the respective receiving wave elements, and calculates the arrival direction of the reflected wave from the target based on the beamforming.

[0035] In the target detection device according to the first mode, it can be configured such that the received wave array includes a plurality of received wave elements, the received wave array is different from the first transmitted wave array, and the received beam generated based on the received signals generated by the respective received wave elements intersects the transmitted beam generated by the first transmitted wave array.

[0036] According to this configuration, in the range where the received beam intersects the transmitted beam (equi-frequency plane), it is possible to calculate the distribution of intensity data based on the intensity of the reflected wave. Thus, by beamforming, the pointing direction of the received beam is changed within the detection range, and it is possible to construct intensity data that is three-dimensionally distributed within the detection range.

[0037] The target detection device according to the first mode is, for example, a sonar that detects targets in water.

[0038] Alternatively, the target detection device according to the first mode may also be a radar that detects targets in the air.

[0039] In the target detection device according to the first mode, the first signal switching unit is controlled such that: in the first timing, for the plurality of first transmitted wave elements between the start element and the end element, as the first timing progresses, the first transmitted signal is continuously supplied from the start element to the end element, thereby supplying the first transmitted signal. In addition, the first signal switching unit may be controlled such that: in the second timing following the first timing, for the plurality of first transmitted wave elements between the start element and the end element, as the second timing progresses, the first transmitted signal is continuously supplied from the start element to the end element, thereby supplying the first transmitted signal.

[0040] According to this configuration, the first transmitted wave elements to which the first transmitted signal is supplied are repeatedly scanned to perform the transmitted wave for one detection unit. Thus, it is possible to increase the transmitted energy for one detection unit. As a result, it is possible to further expand the detection range capable of detecting targets.

[0041] In this configuration, the control unit may also be configured to swap the positions of the start element and the end element after the first timing and before the second timing.

[0042] According to this configuration, the scanning direction corresponding to the plurality of first transmitted wave elements is reversed for each timing. Thus, it is possible to increase the transmitted energy.

[0043] In addition, in the object marker detection device according to the first mode, the first element is supplied with the first part of the first transmission signal, and the second element is supplied with the second part of the first transmission signal that is different from the first part. For example, when a chirp signal or the like is supplied as the first transmission signal, as described above, the parts of the signals supplied to the first element and the second element may be different.

[0044] The second mode of the present invention relates to an object marker detection method. The object marker detection method according to this mode generates a transmission signal and switches the supply of the transmission signal from the first element to the second element within a transmission wave array having a plurality of transmission wave elements.

[0045] According to the object marker detection method according to the second mode, similar to the first mode described above, the transmission wave source of the transmission wave moves in the arrangement direction of the transmission wave elements. Thereby, the same effect as the first mode can be achieved.

[0046] Advantages of the Invention

[0047] As described above, according to the present invention, it is possible to provide an object marker detection device and an object marker detection method that can quickly detect an object to be marked with a simple configuration.

[0048] The advantages and significance of the present invention will become clearer through the description of the embodiments shown below. However, the embodiments shown below are merely examples when implementing the present invention, and the present invention is not limited at all to the forms described in the following embodiments. Brief Description of the Drawings

[0049] Figure 1 (a) of is a diagram showing the configuration of the transmission wave system according to the reference example. Figure 1 (b) of is a diagram showing a configuration example for moving the transmission wave source according to the embodiment.

[0050] Figure 2 (a) of is a diagram showing the simulation result obtained by simulating the composite waveform of the transmission wave at the upper observation position according to the embodiment. Figure 2 (b) of is a diagram showing the simulation result obtained by simulating the composite waveform of the transmission wave at the front observation position according to the embodiment. Figure 2 (c) of is a diagram showing the simulation result obtained by simulating the composite waveform of the transmission wave at the lower observation position according to the embodiment.

[0051] Figure 3 (a) of is a diagram showing the simulation result obtained by simulating the spectrum of the composite waveform of the transmission wave at the upper observation position according to the embodiment. Figure 3(b) is a diagram showing the simulation results obtained by using simulation to find the spectrum of the synthesized waveform of the transmitted waves at the front observation position in the embodiment. Figure 3 (c) is a diagram showing the simulation results obtained by using simulation to find the spectrum of the synthesized waveform of the transmitted waves at the lower observation position in the embodiment.

[0052] Figure 4 is a diagram showing a configuration example for removing unnecessary frequency components in the embodiment.

[0053] Figure 5 (a) is a diagram showing the simulation results obtained by using simulation to find the states of three transmitted waves at the upper observation position in the embodiment. Figure 5 (b) is a diagram showing the simulation results obtained by using simulation to find the Figure 5 synthesized waveform obtained by synthesizing the three transmitted waves in (a) in the embodiment.

[0054] Figure 6 (a) is a diagram showing the simulation results obtained by using simulation to find the states of three transmitted waves at the front observation position in the embodiment. Figure 6 (b) is a diagram showing the simulation results obtained by using simulation to find the Figure 6 synthesized waveform obtained by synthesizing the three transmitted waves in (a) in the embodiment.

[0055] Figure 7 (a) is a diagram showing the simulation results obtained by using simulation to find the states of three transmitted waves at the lower observation position in the embodiment. Figure 7 (b) is a diagram showing the simulation results obtained by using simulation to find the Figure 7 synthesized waveform obtained by synthesizing the three transmitted waves in (a) in the embodiment.

[0056] Figure 8 (a) is a diagram showing the simulation results obtained by using simulation to find the Figure 5 spectrum of the synthesized waveform in (b) in the embodiment. Figure 8 (b) is a diagram showing the simulation results obtained by using simulation to find the Figure 6 spectrum of the synthesized waveform in (b) in the embodiment. Figure 8 (c) is a diagram showing the simulation results obtained by using simulation to find the Figure 7 spectrum of the synthesized waveform in (b) in the embodiment.

[0057] Figure 9 is a diagram showing the simulation results obtained by using simulation to find the equiphase surface in the embodiment.

[0058] Figure 10It is a diagram schematically showing a configuration example of a wave transceiver system related to an embodiment.

[0059] Figure 11 It is a block diagram showing the specific configuration of the target detection device 1 related to the embodiment.

[0060] Figure 12 (a) thereof is a functional block diagram showing a configuration example of the received signal processing unit 133 related to the embodiment. Figure 12 (b) thereof is a functional block diagram showing another configuration example of the received signal processing unit 133 related to the embodiment.

[0061] Figure 13 (a) thereof is a flowchart showing the processing when transmitting a transmission wave from the first transmission wave array related to the embodiment. Figure 13 (b) thereof is a flowchart showing the processing when transmitting a transmission wave from the second transmission wave array related to the embodiment. Figure 13 (c) thereof is a flowchart showing the processing of processing the received signal and displaying a detection image related to the embodiment.

[0062] Figure 14 It is a diagram schematically showing the configuration when the target detection device related to the embodiment is used as a sonar for detecting targets in water.

[0063] Figure 15 (a) thereof is a diagram showing the configuration of the first transmission wave array and the second transmission wave array related to a modification example. Figure 15 (b) thereof is a diagram showing the configuration of the transmission wave array and the signal switching unit related to another modification example.

[0064] Figure 16 It is a diagram schematically showing the state of the sound field when the transmission wave array is scanned multiple times in the second embodiment.

[0065] Figure 17 (a) thereof is a diagram showing, by 3D contour display, the simulation result obtained by simulating the relationship between the spectrum and azimuth of the sound field in the second embodiment. Figure 17 (b) thereof is a diagram showing, by 3D bird's-eye view, the simulation result obtained by simulating the relationship between the spectrum and azimuth of the sound field in the second embodiment.

[0066] Figure 18 (a) thereof is a diagram showing, by 3D contour display, the simulation result obtained by simulating the relationship between the spectrum and azimuth of the sound field in the third embodiment. Figure 18Figure (b) is a diagram showing the simulation results obtained by using simulation to obtain the relationship between the spectrum and azimuth of the sound field in the third embodiment, represented by a 3D bird's-eye view.

[0067] Figure 19 Figure (a) is a diagram showing the simulation results obtained by using simulation to obtain the relationship between the spectrum and azimuth of the sound field in the fourth embodiment, represented by 3D contour display. Figure 19 Figure (b) is a diagram showing the simulation results obtained by using simulation to obtain the relationship between the spectrum and azimuth of the sound field in the fourth embodiment, represented by a 3D bird's-eye view.

[0068] Figure 20 Figure (a) is a diagram showing the simulation results obtained by using simulation to obtain the relationship between the spectrum and azimuth of the sound field in the fifth embodiment, represented by 3D contour display. Figure 20 Figure (b) is a diagram showing the simulation results obtained by using simulation to obtain the relationship between the spectrum and azimuth of the sound field in the fifth embodiment, represented by a 3D bird's-eye view.

[0069] Figure 21 Figure (a) is a graph showing the autocorrelation function at azimuth 0° in the fifth embodiment. Figure 21 Figure (b) is Figure 21 a graph showing an enlarged view of the region from 1 to 4000 μsec in the graph of Figure (a). Figure 21 Figure (c) is a graph showing the autocorrelation function at azimuth 7° in the fifth embodiment. Figure 21 Figure (d) is Figure 21 a graph showing an enlarged view of the region from 1 to 4000 μsec in the graph of Figure (c).

[0070] Figure 22 Figure (a) is a diagram showing the simulation results obtained by using simulation to obtain the relationship between the spectrum and azimuth of the sound field in the fifth embodiment, represented by 3D contour display. Figure 22 Figure (b) is a diagram showing the simulation results obtained by using simulation to obtain the relationship between the spectrum and azimuth of the sound field in the fifth embodiment, represented by a 3D bird's-eye view.

[0071] Figure 23 Figure (a) is a graph showing the autocorrelation function at azimuth 2° in the fifth embodiment. Figure 23 Figure (b) is Figure 23 a graph showing an enlarged view of the region from 1 to 4000 μsec in the graph of Figure (a). Figure 23 Figure (c) is a graph showing the autocorrelation function at azimuth 16° in the fifth embodiment. Figure 23 Figure (d) is Figure 23The graph showing the expansion of the region from 1 to 4000 μsec in the graph of (c).

[0072] Figure 24 It is a diagram schematically showing the state of the sound field when the transmission wave array is scanned back and forth multiple times in the sixth embodiment.

[0073] Figure 25 It is a diagram showing the simulation results obtained by using simulation to obtain the relationship between the spectrum of the sound field and the azimuth in the sixth embodiment. Detailed Embodiment

[0074] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0075] <Basic Configuration>

[0076] First, the basic configuration of the transmission and reception wave system of the target detection device according to the present embodiment will be described.

[0077] Figure 1 (a) is a diagram showing the configuration of the transmission wave system according to the reference example.

[0078] In Figure 1 In the configuration of (a), the transmission wave source R1 is supplied with the transmission signal S1, and the transmission wave is transmitted from the transmission wave source R1. The carrier frequency of the transmission signal S1 is a constant value f0. If the transmission wave source R1 is moved in the moving direction D1 in this state, a change in frequency based on the Doppler effect occurs in the transmission wave observed at the observation position at a predetermined distance from the transmission wave source R1. That is, when the distance between the transmission wave source R1 and the observation position is sufficiently large, at the observation position in the front direction with respect to the middle position of the moving range (hereinafter referred to as the "front observation position"), no change in frequency based on the Doppler effect occurs, and a transmission wave with the same frequency f0 as the transmission signal S1 is generated. In contrast, at the observation position displaced in the direction opposite to the moving direction with respect to the front observation position (hereinafter referred to as the "upper side observation position"), since the transmission wave source R1 moves in the direction away from the observation position, a transmission wave with a frequency f0 - fd lower than the transmission signal S1 is generated due to the Doppler effect. -fd is the frequency change amount with respect to the frequency f0 of the transmission signal S1 caused by the Doppler effect. In addition, at the observation position displaced in the same direction as the moving direction with respect to the front observation position (hereinafter referred to as the "lower side observation position"), since the transmission wave source R1 moves in the direction approaching the observation position, a transmission wave with a frequency f0 + fd higher than the transmission signal S1 is generated due to the Doppler effect. +fd is the frequency change amount with respect to the frequency f0 of the transmission signal S1 caused by the Doppler effect.

[0079] The greater the displacement of the upper and lower observation positions relative to the front observation position, the greater the change in such frequency. That is, corresponding to the magnitudes of the displacement angles in the depression angle direction (the same direction as the moving direction D1) and the elevation angle direction (the direction opposite to the moving direction D1) relative to the front observation position, the frequency of the transmitted wave changes from the frequency f0 in the positive and negative directions. Therefore, when the reflected wave of the transmitted wave is received by the receiving wave element, the magnitudes of the depression angle and the elevation angle can be calculated based on the frequency components of the received signal output from the receiving wave element. In other words, by extracting a specified frequency component from the received signal, the received signal at the specified angular positions in the depression angle direction and the elevation angle direction can be obtained. In the present embodiment, based on this principle, the received signals at the respective angular positions in the depression angle direction and the elevation angle direction are obtained.

[0080] Figure 1 FIG. (b) is a diagram showing a configuration example for moving the transmitted wave source R1.

[0081] In this configuration example, a transmitted wave array 10 in which a plurality of transmitted wave elements 10a are arranged in a column is used. In Figure 1 FIG. (b), for convenience, 8 transmitted wave elements 10a are included in the transmitted wave array 10, but the number of transmitted wave elements 10a is not limited to this. In Figure 1 FIG. (b), for convenience, the transmitted wave elements 10a are sequentially numbered from the top.

[0082] In this configuration example, the signal switching unit 20 switches the connection of the input terminal of the transmission signal S1 to each transmitted wave element 10a. The signal switching unit 20 is constituted by, for example, a signal splitter. Here, the transmitted wave element 10a as the supply destination of the transmission signal S1 is switched to the adjacent transmitted wave element 10a sequentially from the top. Thus, the transmitted wave source of the transmitted wave moves in the D1 direction. According to this configuration example, similar to the case of Figure 1 FIG. (a), a change in frequency based on the Doppler effect is generated at each observation position.

[0083] However, in this configuration example, due to the switching of the transmitted wave element 10a of the transmitted wave, the continuity of the transmitted wave at the upper and lower observation positions is interrupted. Figure 1 The waveform on the right side of FIG. (b) represents the waveforms of the transmitted waves at three observation positions. These three observation positions are the same as the three observation positions (upper observation position, front observation position, lower observation position) in Figure 1 FIG. (a). TD1, TD2, and TD3 represent the transmitted waves transmitted by the topmost transmitted wave element 10a, the second transmitted wave element 10a from the top, and the third transmitted wave element 10a from the top, respectively.

[0084] As shown in Figure 1As shown in (b), the transmitted wave at the front observation position is not affected by the Doppler effect, so Figure 1 Similar to the case of (a), the continuity of the transmitted waves TD1 to TD3 is ensured. In contrast, at the upper observation position, due to the Doppler effect, the phases of the transmitted waves TD1 to TD3 are delayed, so the transmitted waves TD1 to TD3 are separated from each other, and the transmitted waves TD1 to TD3 become discrete. Also, at the lower observation position, due to the Doppler effect, the phases of the transmitted waves TD1 to TD3 are advanced, so the transmitted waves TD1 to TD3 approach each other, and the transmitted waves TD1 to TD3 become discrete.

[0085] In this way, in this configuration example, the following phenomenon occurs: The frequency of the waveform itself at each observation position Figure 1 is the same as that in the case of (a), and changes as the observation position moves away from the front observation position in the depression angle direction and the elevation angle direction. However, the transmitted waves transmitted from each transmitting wave element 10a become discrete at the upper observation position and the lower observation position. Therefore, in this configuration example, since the transmitted waves become discrete, useless frequency components are generated in the transmitted waves.

[0086] Figure 2 Figures (a) to (c) show the simulation results obtained by simulating the composite waveforms of the transmitted waves at the three observation positions shown in Figure 1 (b).

[0087] In this simulation, the separation distance of the front observation position from the transmitting wave array 10 is set to the far field. Also, the position displaced 30° upward from the front observation position is set as the upper observation position, and the position displaced 30° downward from the front observation position is set as the lower observation position. Figure 2 (b) is the waveform of the transmitted wave at the front observation position, Figure 2 (a) and (c) are the waveforms of the transmitted waves at the upper observation position and the lower observation position, respectively. In each graph, the horizontal axis is the number of data points, and the vertical axis is the amplitude of the transmitted wave. Here, each transmitting wave element 10a is supplied with a transmission signal of several cycle amounts and transmits a transmitted wave. The frequency f0 of the transmission signal is set to 150 kHz.

[0088] As Figure 2 (b) shows, at the front observation position, the continuity of the transmitted waves TD1, TD2, and TD3 is ensured. In contrast, at the upper observation position, as Figure 2 (a) shows, between the transmitted waves TD1, TD2, and TD3, flat waveform portions are generated due to the separation of each waveform. Also, at the lower observation position, as Figure 2As shown in (c), between the transmitted waves TD1, TD2, and TD3, there is a waveform portion with a steep amplitude caused by the overlap of each waveform.

[0089] Figure 3 (a) to (c) show the simulation results obtained by simulating the spectrum of the combined waveform at three observation positions. Figure 2 The figures (a) to (c) show the simulation results obtained by simulating the spectrum of the combined waveform at three observation positions shown. Figure 3 (b) shows the spectrum of the combined waveform at the front observation position. Figure 3 (a) and (c) show the spectra of the combined waveforms at the upper and lower observation positions, respectively.

[0090] As Figure 3 shown in (b), in the combined waveform at the front observation position, a peak with a large amplitude is generated near 150 kHz, which is the frequency f0 of the transmitted signal. However, in Figure 3 the spectrum of (b), amplitudes are also generated over a wide range outside the position of the normal frequency near 150 kHz.

[0091] In addition, referring to Figure 3 the spectrum at the upper observation position in (a), although a peak is generated near 145 kHz, which is the frequency decreased from the transmitted signal frequency f0 due to the Doppler effect, amplitudes are generated over a wide range outside this frequency. Similarly, referring to Figure 3 the spectrum at the lower observation position in (c), although a peak is generated near 155 kHz, which is the frequency increased from the transmitted signal frequency f0 due to the Doppler effect, amplitudes are generated over a wide range outside this frequency.

[0092] In this way, in the above-described configuration example, at each observation position, amplitudes are generated over a wide range of frequencies outside the frequency that should be generated due to the Doppler effect. Such unnecessary frequency components become noise for measuring the original reflected wave at each observation position, and thus it is preferably removed as much as possible.

[0093] Figure 4 The figure shows a configuration example for removing unnecessary frequency components.

[0094] In this configuration example, a first transmitted wave array 11 in which a plurality of first transmitted wave elements 11a are arranged in a column and a second transmitted wave array 12 in which a plurality of second transmitted wave elements 12a are arranged in a column are used. In Figure 4 for convenience, each of the first transmitted wave array 11 and the second transmitted wave array 12 includes four transmitted wave elements, but the number of transmitted wave elements is not limited to this. In addition, in Figure 4In this case, for convenience, the first transmission wave elements 11a and the second transmission wave elements 12a are sequentially numbered from the top. For distinction, the second transmission wave elements 12a are shaded.

[0095] In this configuration example, the second transmission wave elements 12a are arranged between adjacent first transmission wave elements 11a. A plurality of first transmission wave elements 11a and a plurality of second transmission wave elements 12a are arranged on the same straight line.

[0096] The first signal switching unit 21 switches the connection of the input terminal of the first transmission signal S11 to the first transmission wave element 11a. In addition, the second signal switching unit 22 switches the connection of the input terminal of the second transmission signal S12 to the second transmission wave element 12a. The first signal switching unit 21 and the second signal switching unit 22 are constituted by, for example, a signal splitter. Here, the first transmission wave elements 11a as the supply destinations of the first transmission signal S11 are sequentially switched to the adjacent first transmission wave elements 11a from the top. In addition, the second transmission wave elements 12a as the supply destinations of the second transmission signal S12 are sequentially switched to the adjacent second transmission wave elements 12a from the top.

[0097] After the first transmission signal S11 is supplied to one first transmission wave element 11a, at a timing that is half of the supply period of the first transmission signal S11, the second transmission signal S12 is supplied to the second transmission wave element 12a adjacent to the first transmission wave element 11a. That is, the supply timing of the first transmission signal S11 and the supply timing of the second transmission signal S12 are deviated by half of the length of the first transmission signal S11 or the second transmission signal S12. As a result, the transmission wave source of the transmission wave moves in the D1 direction. Therefore, according to this configuration example, as in Figure 1 the case of (a), a change in the frequency based on the Doppler effect is generated at each observation position.

[0098] In this configuration example, the carrier frequency of the first transmission signal S11 and the carrier frequency of the second transmission signal S12 are set to a constant value and the same value f0. However, in this configuration example, the first transmission signal S11 and the second transmission signal S12 are modulated by a prescribed modulation method. Specifically, the amplitudes of the first transmission signal S11 and the second transmission signal S12 are modulated so that no unnecessary frequency components are generated in the composite waveform at each observation position. As a method of amplitude modulation, a method based on a triangular window function or a method based on a Hann window function can be used.

[0099] Figure 4 The waveform on the right side of Figure 1The three observation positions (upper observation position, front observation position, lower observation position) in (b) are the same. TD11 and TD12 represent the transmitted waves respectively transmitted by the first and second transmitted wave elements 11a at the first and second positions from the top of the first transmitted wave array 11. In addition, TD21 and TD22 represent the transmitted waves respectively transmitted by the first and second transmitted wave elements 12a at the first and second positions from the top of the second transmitted wave array 12.

[0100] In this structural example, similar to Figure 1 the case of (b), the transmitted waves TD11 and TD12 at the upper observation position are separated from each other. However, since the transmitted wave TD21 is interposed in this separated portion, in the synthesized waveform obtained by synthesizing them, a flat portion is not generated in this portion, suppressing the generation of unnecessary frequency components based on the flat portion.

[0101] In addition, in this structural example, similar to Figure 1 the case of (b), a part of the transmitted waves TD11 and TD12 at the lower observation position overlaps. However, since the transmitted wave TD21 is interposed in this overlapping portion, in the synthesized waveform obtained by synthesizing them, a steep amplitude portion is not generated in this portion, suppressing the generation of unnecessary frequency components based on the steep amplitude portion.

[0102] Figure 5 (a) is a diagram showing the simulation result obtained by simulating the states of the transmitted waves TD11, TD12, and TD21 at the upper observation position. In addition, Figure 5 (b) is a diagram showing the simulation result obtained by simulating the synthesized waveform obtained by synthesizing the transmitted waves TD11, TD12, and TD21 in (a) of Figure 5 .

[0103] Figure 5 The vertical axis and the horizontal axis of (a) and (b) of Figure 2 are the same as the vertical axis and the horizontal axis of (a) of Figure 2 . The upper observation position is set in the same way as the case of (a) of Figure 5 . In (a) of

[0104] In this simulation, the amplitude of the first transmission signal S11 was modulated so as to be maximized at the middle of the supply period for each first transmission wave element 11a and to approach zero at the start and end of the supply period. The second transmission signal S12 was modulated in the same manner. The frequencies of the first transmission signal S11 and the second transmission signal S12 were set to be the same. The time length of the supply period of the first transmission signal S11 for the first transmission wave element 11a was the same as the time length of the supply period of the second transmission signal S12 for the second transmission wave element 12a.

[0105] As Figure 5 shown in (b), in the composite waveform at the upper observation position, although a slight change in amplitude occurred, there was no flat portion in the composite waveform as Figure 2 shown in (a), and furthermore, the continuity of the composite waveform was ensured.

[0106] Figure 6 (a) is a diagram showing the simulation results obtained by simulating the states of the transmission waves TD11, TD12, and TD21 at the front observation position. In addition, Figure 6 (b) is a diagram showing the simulation results obtained by simulating the composite waveform obtained by combining the transmission waves TD11, TD12, and TD21 in Figure 6 (a).

[0107] Figure 6 The vertical and horizontal axes of (a) and (b) are the same as the vertical and horizontal axes of Figure 5 (a) and (b). The front observation position was set in the same manner as in Figure 2 (b). In Figure 6 (a), the transmission waves TD11 and TD12 are represented by solid lines, and the transmission wave TD21 is represented by a dashed line. In this simulation, the first transmission signal S11 and the second transmission signal S12 that were the same as those in the simulation of Figure 5 (a) and (b) were also used.

[0108] As Figure 6 shown in (b), in the composite waveform at the front observation position, similar to the case of Figure 2 (b), the amplitude was maintained to be approximately constant, and the continuity of the composite waveform was ensured.

[0109] Figure 7 (a) is a diagram showing the simulation results obtained by simulating the states of the transmission waves TD11, TD12, and TD21 at the lower observation position. In addition, Figure 7 (b) is a diagram showing the simulation results obtained by simulating the composite waveform obtained by combining the transmission waves TD11, TD12, and TD21 in Figure 7 (a).

[0110] Figure 7 The vertical and horizontal axes of (a) and (b) are respectively the same as those of Figure 5 The vertical and horizontal axes of (a) and (b) are the same. The lower observation position is set in the same way as in the case of Figure 2 (c). In Figure 7 (a), the transmitted waves TD11 and TD12 are represented by solid lines, and the transmitted wave TD21 is represented by a dotted line. In this simulation, the first transmission signal S11 and the second transmission signal S12, which are the same as those in the simulation of Figure 5 (a) and (b), are also used.

[0111] As Figure 7 shown in (b), in the composite waveform at the lower observation position, although a slight change in amplitude occurs, there is no steep amplitude part in the composite waveform as in Figure 2 (c), and the continuity of the composite waveform is ensured.

[0112] Figure 8 (a) - (c) respectively show the simulation results obtained by simulating the frequency spectra of the composite waveforms shown in Figure 5 (b), Figure 6 (b), and Figure 7 (b).

[0113] As Figure 8 shown in (a), the frequency spectrum of the composite waveform at the upper observation position is the same as that of Figure 3 (a), and a peak occurs near 145 kHz, which is the frequency offset position based on the Doppler effect. In addition, in the frequency spectrum of Figure 8 (a), compared with the frequency spectrum of Figure 3 (a), the useless peaks are removed, and the range of frequencies at which the amplitude is generated is also limited to a very small range centered around 150 kHz.

[0114] As Figure 8 shown in (b), the frequency spectrum of the composite waveform at the front observation position is the same as that of Figure 3 (b), and peaks occur near 150 kHz, which is the same as the frequencies of the first transmission signal S11 and the second transmission signal S12. In addition, in the frequency spectrum of Figure 8 (b), compared with the frequency spectrum of Figure 3 (b), the range of frequencies at which the amplitude is generated is limited to a very small range centered around 150 kHz.

[0115] As Figure 8 shown in (c), the frequency spectrum of the composite waveform at the lower observation position is the same as that of Figure 3The spectrum of (c) also generates a peak near the offset position of the frequency based on the Doppler effect, i.e., around 155 kHz. Additionally, in Figure 8 the spectrum of (c), compared with Figure 3 the spectrum of (c), useless peaks are removed, and moreover, the range of frequencies generating the amplitude is also limited to a very small range centered around 150 kHz.

[0116] In this way, by using the Figure 4 configuration, it is possible to effectively remove the useless frequency components of the transmitted wave that may become noise at each observation position. Thus, it is possible to measure the reflected wave more accurately.

[0117] Additionally, Figure 1 the change in the frequency based on the Doppler effect shown in (b) of Figure 4 occurs not only at the above-mentioned front observation position, upper side observation position, and lower side observation position, but also at other observation positions within the range where the transmitted wave is sent. Among them, due to the different positional relationships of each observation position with respect to the transmitted wave source, the generation manner of the Doppler effect is also different at each observation position. That is, for each observation position on a plane having a specified elevation angle or depression angle with respect to the front direction, since the heights with respect to the horizontal plane including the front direction are different from each other, when the transmitted wave source moves, the approaching or separating speeds with respect to the transmitted wave source are different from each other. Therefore, the plane where the frequencies of the transmitted wave are equal is not a plane having a specified elevation angle or depression angle with respect to the front direction, but a curved surface formed by bending this plane in the circumferential direction.

[0118] Figure 9 is a diagram showing the simulation results obtained by simulating the plane where the frequencies are equal (hereinafter referred to as the "equal frequency plane").

[0119] In Figure 9 , the unit of each axis is meters. At the intermediate position in the Y-axis direction (the position where the distance is zero), the transmitted wave array is arranged to extend in the X-axis direction. The transmitted wave is sent from the intermediate position in the Y-axis direction toward the Z-axis direction. That is, the direction from the intermediate position in the Y-axis direction toward the Z-axis direction is the front direction.

[0120] In Figure 9 , the equal frequency planes EP1 to EP5 in the range above the front direction are shown. The equal frequency planes EP1, EP2, EP3, EP4, and EP5 are the planes of the frequencies f0 - fd1, f0 - fd2, f0 - fd3, f0 - fd4, and f0 - fd5, respectively. f0 is the frequency in the front direction and is equal to the frequency of the transmitted signal supplied to the transmitted wave element. There is a relationship of fd1 < fd2 < fd3 < fd4 < fd5 for fd1 to fd5.

[0121] For convenience, five equi-frequency surfaces EP1 to EP5 are shown in Figure 9 , but there are also multiple equi-frequency surfaces between these equi-frequency surfaces EP1 to EP5. For example, the frequency in the gap between equi-frequency surfaces EP1 and EP2 continuously changes from f0 - fd1 to f0 - fd2. By folding back the equi-frequency surfaces EP1 to EP5 of Figure 9 symmetrically with respect to the Y-Z plane, equi-frequency surfaces in the range below the front direction are formed.

[0122] Figure 10 is a diagram schematically showing a configuration example of a transmitting and receiving wave system.

[0123] In this configuration example, in addition to the configuration of the transmitting wave system shown in Figure 4 , a receiving wave array 31 having a plurality of receiving wave elements 31a is also arranged as a configuration of the receiving wave system. Similarly to Figure 4 , the configuration of the transmitting wave system includes a first transmitting wave array 11 and a second transmitting wave array 12. The first transmitting wave array 11 and the second transmitting wave array 12 are arranged along the X axis. The receiving wave array 31 is arranged directly above the first transmitting wave array 11. In this configuration example, the arrangement direction of the receiving wave elements 31a is perpendicular to the arrangement directions of the first transmitting wave element 11a and the second transmitting wave element 12a.

[0124] Using the method described with reference to Figure 4 , the first transmitting wave element 11a in the first transmitting wave array 11 and the second transmitting wave array 12 in the second transmitting wave array 12 are driven, so that a transmitting beam TB1 is formed in front of (in the positive Z-axis direction) the first transmitting wave array 11 and the second transmitting wave array 12.

[0125] That is, if the first transmission signal S11 is supplied to the first transmitting wave element 11a, a transmitting wave is transmitted from this first transmitting wave element 11a with a relatively wide directivity. Similarly, if the second transmission signal S12 is supplied to the second transmitting wave element 12a, a transmitting wave is transmitted from this second transmitting wave element 12a with a relatively wide directivity. When the first transmission signal S11 and the second transmission signal S12 are supplied to the first transmitting wave element 11a in the first transmitting wave array 11 and the second transmitting wave element 12a in the second transmitting wave array 12 in order from the top with a one-time scanning amount, the region where the transmitting waves transmitted from each transmitting wave element all overlap becomes the formation region of the transmitting beam TB1. In this formation region, as described with reference to Figure 9 , multiple equi-frequency surfaces are generated.

[0126] Phase control (beamforming) is performed on the received signals output from each receiving wave element 31a, thereby forming a receiving beam RB1 with a narrow width in the circumferential direction centered on the X-axis. Thus, the received signals in the region where the receiving beam RB1 intersects the transmitting beam TB1 are extracted. Through the above-described phase control, the receiving beam RB1 is rotated in the θ1 direction centered on the X-axis, thereby extracting the received signals at each rotation position. Based on the rotation position of the receiving beam RB1, the arrival direction of the reflected wave formed by the reflection of the transmitted wave by the target in the horizontal direction can be specified. In addition, based on the frequency of the received signal, an isofrequency surface where the reflected wave is generated can be specified (refer to Figure 9 ).

[0127] Therefore, by extracting, from among the received signals extracted from the receiving beam RB1, the received signals having frequencies corresponding to the respective isofrequency surfaces, and plotting the intensities of the extracted received signals on the respective isofrequency surfaces, the distribution of the intensity data of the received signals in the range where the receiving beam RB1 intersects the transmitting beam TB1 can be obtained. Then, by rotating the receiving beam RB1 within the detection range in the horizontal direction and obtaining the distribution of the intensity data at each rotation position, the intensity data (volume data) distributed in a three-dimensional shape in the entire detection range in the horizontal and vertical directions can be acquired. By converting this intensity data (volume data) into an image, an image representing the state of the target in the detection range can be obtained.

[0128] <Specific Configuration>

[0129] Figure 11 is a block diagram showing the specific configuration of the target detection device 1.

[0130] The target detection device 1 includes the above-described first transmitting wave array 11 and second transmitting wave array 12 as components of the transmitting wave system. The first transmitting wave array 11 and the second transmitting wave array 12 have the same configuration as Figure 10 . The target detection device 1 includes a first transmission signal generation unit 111, a first transmission amplifier 112, and a first signal switching unit 113 as components for supplying a first transmission signal S11 to each first transmitting wave element 11a of the first transmitting wave array 11. In addition, the target detection device 1 includes a second transmission signal generation unit 121, a second transmission amplifier 122, and a second signal switching unit 123 as components for supplying a second transmission signal S12 to each second transmitting wave element 12a of the second transmitting wave array 12.

[0131] The first transmission signal generation unit 111 generates a first transmission signal S11 according to the control from the control unit 101. The first transmission signal S11 is a waveform having a constant frequency and subjected to amplitude modulation. The first transmission signal S11 can be set, for example, to be the same as Figure 6The transmitted wave TD11 in (a) has the same waveform. The first transmission amplifier 112 amplifies the first transmission signal S11 input from the first transmission signal generation unit 111 under the control of the control unit 101. The first signal switching unit 113 sequentially supplies the first transmission signal S11 to a plurality of first transmission wave elements 11a included in the first transmission wave array 11 under the control of the control unit 101. The first signal switching unit 113 has the same configuration as the Figure 4 first signal switching unit 21. The first signal switching unit 113 is constituted by, for example, a signal separator.

[0132] The second transmission signal generation unit 121 generates a second transmission signal S12 under the control of the control unit 101. The second transmission signal S12 has a waveform with a constant frequency and amplitude modulation. The second transmission signal S12 can be set, for example, to have the same waveform as the Figure 6 transmitted wave TD21 in (a). The second transmission signal S12 is the same signal as the first transmission signal S11. The second transmission amplifier 122 amplifies the second transmission signal S12 input from the second transmission signal generation unit 121 under the control of the control unit 101. The second signal switching unit 123 sequentially supplies the second transmission signal S12 to a plurality of second transmission wave elements 12a included in the second transmission wave array 12 under the control of the control unit 101. The second signal switching unit 123 has the same configuration as the Figure 4 second signal switching unit 22. The second signal switching unit 123 is constituted by, for example, a signal separator.

[0133] The control unit 101 includes an arithmetic processing circuit such as a CPU (Central Processing Unit), and storage media such as a ROM (Read Only Memory), a RAM (Random Access Memory), and a hard disk. The control unit 101 can also be constituted by an integrated circuit such as an FPGA (Field-Programmable Gate Array). The control unit 101 controls the first signal switching unit 113 and the second signal switching unit 123 so that the supply period of the second transmission signal S12 to the second transmission wave element 12a adjacent to the first transmission wave element 11a is delayed by half a period with respect to the supply period of the first transmission signal S11 to the first transmission wave element 11a. Thus, the transmitted waves having the waveforms shown in (b) of Figure 5 (b), Figure 6 (b), and Figure 7 (b) form the above-described equal-frequency surface in the transmission beam TB1 (refer to Figure 9 ).

[0134] The target detection device 1 includes the above-described reception wave array 31 as a component of the reception wave system. The reception wave array 31 has the same configuration as Figure 10 . m reception wave elements 31a are arranged in the reception wave array 31. Reception signals are output from each of the reception wave elements 31a to the corresponding channels CH1 to CHm.

[0135] The target detection device 1 includes a plurality of reception processing units 131, a plurality of AD conversion units 132, a reception signal processing unit 133, and an image signal processing unit 134 as components for processing the reception signals output from the respective reception wave elements 31a of the reception wave array 31 and generating a detection image.

[0136] The plurality of reception processing units 131 are respectively connected to the channels CH1 to CHm. Each reception processing unit 131 performs processing for removing unnecessary frequency bands, processing for amplifying the reception signal to a level suitable for AD conversion, and processing for removing signal components in a frequency band that is more than half of the sampling period of the AD conversion, etc., on the input reception signal. The plurality of AD conversion units 132 are respectively associated with the plurality of reception processing units 131. Each AD conversion unit 132 converts the analog reception signal input from the corresponding reception processing unit 131 into a digital signal at a prescribed sampling period.

[0137] The reception signal processing unit 133 processes the reception signals of the channels CH1 to CHm respectively input from the plurality of AD conversion units 132, and calculates intensity data (volume data) of the reception signals distributed three-dimensionally in the detection range. The reception signal processing unit 133 may be constituted by a single integrated circuit (such as an FPGA) together with the control unit 101.

[0138] The image signal processing unit 134 processes the intensity data (volume data) input from the reception signal processing unit 133, and generates image data for making the state of the target in the detection range into an image. The image signal processing unit 134 is constituted by a CPU, for example. The display unit 135 is constituted by a monitor or the like, and displays a detection image corresponding to the image data input from the image signal processing unit 134.

[0139] Figure 12 Fig. (a) shows a functional block diagram of a configuration example of the reception signal processing unit 133.

[0140] The reception signal processing unit 133 includes an arithmetic processing circuit and a storage medium. The reception signal processing unit 133 executes the functions of each functional module shown in Fig. (a) of Figure 12 according to the program stored in the storage medium. Figure 12 Part of the functions shown in Fig. (a) of

[0141] The received signal processing unit 133 includes a plurality of digital filters 201, buffers 202, a plurality of band-pass filters 203, and a plurality of beam combining units 204.

[0142] The plurality of digital filters 201 are respectively provided corresponding to Figure 11 the plurality of AD conversion units 132. The digital filter 201 is a filter with a steeper filter function than the filter in the received signal processing unit 131 of Figure 11 , and removes signals in the useless frequency band in the received signal.

[0143] The buffer 202 temporarily holds the received signals of channels CH1 to CHm respectively output from the plurality of digital filters 201. The buffer 202 holds the received signals of multiple scan amounts in time sequence. One scan amount of received signal is the received signal during the period from the start of the process of driving the plurality of first transmission wave elements 11a of the first transmission wave array 11 and the plurality of second transmission wave elements 12a of the second transmission wave array 12 from top to bottom (hereinafter this driving is referred to as "scan") until the reflected wave from the maximum distance in the detection range is received by the receiving wave array 31 (hereinafter referred to as "one scan amount of received signal"). The buffer 202 sequentially supplies one scan amount of received signal to the plurality of band-pass filters 203 respectively. If the buffer 202 supplies one scan amount of received signal to the plurality of band-pass filters 203, it deletes the one scan amount of received signal.

[0144] The plurality of band-pass filters 203 respectively extract the frequency components of frequencies F1 to Fn (equal-frequency received signals) from the one scan amount of received signals of channels CH1 to CHm. The frequencies F1 to Fn of the band-pass filters 203 define Figure 9 the equal-frequency surfaces shown. That is, the equal-frequency surfaces are defined by the number of band-pass filters 203. The higher the number of band-pass filters 203, the higher the resolution of the received signals in the overlapping direction of the equal-frequency surfaces. The band-pass filter 203 extracts the frequency component (equal-frequency received signal) of the frequency Fk set for itself from the one scan amount of received signals of channels CH1 to CHm and supplies it to the beam combining unit 204.

[0145] The plurality of beam combining units 204 are respectively provided corresponding to the plurality of band-pass filters 203. The beam combining unit 204 forms a received beam RB1 through beamforming based on phase control or delay control, and Figure 10 separates the equal-frequency received signals at a specified resolution in the θ1 direction of Figure 10The equal-frequency received signals in the cross-region where the receiving beams RB1 in each azimuth in the θ1 direction cross.

[0146] The intensity of the obtained equal-frequency received signals changes on the time axis corresponding to the intensity of the reflected waves from the cross-region. This time axis corresponds to the distance from the receiving wave array 31 in the cross-region. Therefore, by mapping each intensity on the time axis to the corresponding distance position from the receiving wave array 31 in the cross-region, the distribution of the intensity data on the cross-region can be obtained. In this way, by synthesizing the distributions of the intensity data for each azimuth output from each beam synthesizing unit 204, volume data in which the intensity data is distributed in a three-dimensional shape in the detection range is obtained.

[0147] Figure 12 (b) is a functional block diagram showing another configuration example of the received signal processing unit 133.

[0148] In this configuration example, the Figure 12 band-pass filter 203 in the configuration example of (a) is replaced with an FFT (Fast Fourier Transform) 211 and a frequency extraction unit 212. The FFT 211 calculates the spectrum based on the received signals of the first scan amounts of channels CH1 to CHm. The frequency extraction unit 212 extracts the frequency components (equal-frequency received signals) of frequencies F1 to Fn from the spectra of the respective channels calculated by the FFT 211 and supplies them to the beam synthesizing unit 204. The processing of the beam synthesizing unit 204 is the same as that in the case of Figure 12 (a).

[0149] According to this configuration, similar to the configuration of Figure 12 (a), by synthesizing the distributions of the intensity data for each azimuth output from each beam synthesizing unit 204, volume data in which the intensity data is distributed in a three-dimensional shape in the detection range is obtained. In addition, in the configuration example of Figure 12 (b), compared with the configuration example of Figure 12 (a), the frequencies for extracting the equal-frequency received signals can be set more finely. As a result, the number of equal-frequency surfaces to be processed can be increased, and the resolution of the equal-frequency received signals in the stacking direction of the equal-frequency surfaces can be improved.

[0150] Figure 13 (a) and (b) are flowcharts of the transmitted wave processing performed by the Figure 11 control unit 101. This processing is continuously executed during the detection operation and ends with the end of the detection operation.

[0151] Refer to Figure 13(a), the control unit 101 causes the first transmission signal generation unit 111 to generate a first transmission signal S11 (S111). Thereafter, if the specified switching timing is reached (S112: yes), the control unit 101 switches the first transmission wave element 11a, which is the supply destination of the first transmission signal S11, to the adjacent first transmission wave element 11a (S113). Here, the switching timing is the timing when the end of one unit of the first transmission signal S11 (the first transmission signal S11 corresponding to the transmission wave TD11 in (a) of Figure 6 arrives after amplitude modulation. Thereafter, the control unit 101 returns the process to step S112 and waits for the next switching timing to arrive. Thus, at the start timing of one unit of the first transmission signal S11, the first transmission wave element 11a, which is the supply destination of the first transmission signal S11, is switched to the adjacent first transmission wave element 11a.

[0152] Refer to Figure 13 (b), the control unit 101 causes the second transmission signal generation unit 121 to generate a second transmission signal S12 (S121) at a timing delayed by half of one unit of the first transmission signal from the start timing of the generation of the first transmission signal S11. As described above, the second transmission signal S12 is a signal having the same frequency and amplitude modulation as the first transmission signal S11. Thereafter, if the specified switching timing is reached (S122: yes), the control unit 101 switches the second transmission wave element 12a, which is the supply destination of the second transmission signal S12, to the adjacent second transmission wave element 12a (S123). Here, the switching timing is the timing when the middle position of one unit of the first transmission signal S11 supplied to the first transmission wave element 11a adjacent to the second transmission wave element 12a, which is the current supply destination, arrives. Thereafter, the control unit 101 returns the process to step S122 and waits for the next switching timing to arrive. Thus, at a timing delayed by half of one unit with respect to the first transmission signal S11, the second transmission wave element 12a, which is the supply destination of the second transmission signal S12, is switched to the adjacent second transmission wave element 12a.

[0153] The control unit 101, through Figure 13 the processes of (a) and (b), sequentially switches the first transmission wave element 11a and the second transmission wave element 12a, which are respectively supplied with the first transmission signal S11 and the second transmission signal S12, from the top. If the supply destination is switched to the lowermost first transmission wave element 11a and second transmission wave element 12a and one scan is completed, the control unit 101 again returns the supply destination to the uppermost first transmission wave element 11a and second transmission wave element 12a and performs the next scan through the same process. In each scan, as referred to in Figure 4Transmit waves as described. Thereby, a transmit beam TB1 with overlapping equal-frequency surfaces as described above is formed.

[0154] Figure 13 (c) is a flowchart showing the process of processing the received signal and displaying the detection image. This process is continuously executed during the detection operation and ends with the completion of the detection operation.

[0155] Supply the received signal of one scan amount from the buffer 202 to each of the plurality of band-pass filters 203 (S201). Each band-pass filter 203 extracts the frequency component of its own set frequency (equal-frequency received signal) from the received signals of the respective input channels and supplies it to the corresponding beam synthesis unit 204 (S202). The beam synthesis unit 204 extracts the signal components of each azimuth in the horizontal direction (θ1 direction) from the input frequency components (equal-frequency received signals) by beamforming (S203). Thereby, a distribution of intensity data obtained by mapping the intensity data of the received signal to the equal-frequency surfaces defined by each frequency can be obtained. The received signal processing unit 133 synthesizes the intensity data from all the beam synthesis units 204 to form volume data in which the intensity data is distributed in a three-dimensional shape within the detection range (S204). The received signal processing unit 133 supplies the volume data to the image signal processing unit 134.

[0156] The image signal processing unit 134 processes the volume data to generate image data for displaying the detection status of the target in the detection range, and supplies the generated image data to the display unit 135 (S205). The display unit 135 displays an image based on the input image data (S206). Thereby, the detection status of the target in the detection range is displayed.

[0157] Figure 14 is a diagram schematically showing the configuration when the above-described target detection device 1 is used as a sonar for detecting targets in water.

[0158] A transceiver 300 is provided at the bottom of the ship 2. The transceiver 300 includes a first transmit wave array 11, a second transmit wave array 12, and a receive wave array 31. The first transmit wave array 11 and the second transmit wave array 12 transmit transmit waves into the water through the above-described process. Here, acoustic waves (such as ultrasonic waves) are transmitted as transmit waves. Thereby, within the range of the angle θ2 parallel to the vertical plane, a transmit beam TB1 with overlapping equal-frequency surfaces in the angular direction is formed.

[0159] Figure 11Constitutions other than the first transmission wave array 11, the second transmission wave array 12, the reception wave array 31, and the display unit 135 among the constitutions are equipped in a control device provided in the steering room 2a of the ship 2. The display unit 135 and the control device are respectively provided in the steering room 2a. The display unit 135 may also be integrated with the control device.

[0160] According to this constitution, a detection image indicating the conditions of the water bottom 3 and the fish school 4 is displayed on the display unit 135. Thereby, the user can grasp the conditions in the water. In addition, four transceivers 300 may be provided on the bottom of the ship, respectively facing forward, backward, left, and right. In this case, the constitutions of the transmission wave system and the reception wave system are prepared for each transceiver 300. Figure 11 Thereby, the display unit 135 can display a detection image of the entire periphery of the ship.

[0161] In addition, when the above-described target detection device 1 is used as a radar for detecting targets in the air, for example, a transceiver 400 is provided on the side wall of the steering room 2a. The transceiver 400 includes the first transmission wave array 11, the second transmission wave array 12, and the reception wave array 31. The first transmission wave array 11 and the second transmission wave array 12 transmit transmission waves into the air through the above-described processing. Here, the transmitted electric wave is used as the transmission wave. The constitution of the circuit unit is provided in the steering room 2a in the same manner as in the case of the sonar.

[0162] According to this constitution, a detection image indicating the conditions of obstacles, bird flocks, etc. is displayed on the display unit 135. Thereby, the user can grasp the conditions in the air. In addition, transceivers 400 may be provided on the front, rear, left, and right sides of the steering room 2a, respectively. In this case, the constitutions of the transmission wave system and the reception wave system are prepared for each transceiver 400. Figure 11 Thereby, the display unit 135 can display a detection image of the entire surrounding space of the ship.

[0163] <Effect of the Embodiment>

[0164] According to the embodiment, the following effects can be obtained.

[0165] By switching the first transmission wave element 11a to which the first transmission signal S11 is supplied from the first element to the second element within the first transmission wave array 11, the transmission wave source of the transmission wave moves in the arrangement direction of the first transmission wave elements 11a. As a result, the frequency of the transmission beam TB1 changes in the moving direction of the transmission wave source due to the Doppler effect, and a plurality of equal-frequency surfaces are formed in the transmission beam TB1. Therefore, by extracting the frequency components corresponding to the respective equal-frequency surfaces from the reception signal generated by the reception wave element 31a, it is possible to obtain a reception signal (equal-frequency reception signal) based on the reflected waves from the respective equal-frequency surfaces. In this way, according to the present embodiment, by switching the first transmission wave element 11a to which the first transmission signal S11 is supplied within the first transmission wave array 11, it is possible to simultaneously generate equal-frequency reception signals corresponding to all the equal-frequency surfaces of the observation object. Thereby, it is possible to quickly detect a target with a simple configuration.

[0166] In addition, in the present embodiment, the first transmission signal S11 is sequentially supplied to adjacent first transmission wave elements 11a, so that the transmission wave source of the transmission wave can be finely moved in the arrangement direction of the first transmission wave elements 11a. As a result, the change in frequency caused by the Doppler effect can be smoothly generated.

[0167] In addition, in Figure 4 and Figure 10 In the configuration example shown, a second transmission wave array 12 having a plurality of second transmission wave elements 12a is provided, and the second transmission signal S12 is sequentially supplied to the plurality of second transmission wave elements 12a. As a result, by adjusting the first transmission signal S11 and the second transmission signal S12, it is possible to suppress the overlapping of unnecessary frequency components on the transmission wave. Thereby, it is possible to perform processing based on the reception signal with higher accuracy.

[0168] In addition, since the second transmission wave element 12a is adjacent to the first transmission wave element 11a, during the period when the transmission wave source of the transmission wave based on the first transmission signal S11 moves from the first element to the second element within the first transmission wave array 11, at the position between the first element and the second element, a transmission wave based on the second transmission signal S12 is transmitted from the second transmission wave element 12a within the second transmission wave array 12. As a result, it is easy to maintain the continuity of the transmission wave. Thereby, it is possible to suppress the overlapping of unnecessary frequency components on the transmission wave.

[0169] In addition, in this configuration, by modulating the amplitudes of the first transmission signal S11 and the second transmission signal S12, for example, like the waveform of (a) in Figure 5 , it is possible to more effectively suppress the overlapping of unnecessary frequency components on the transmission wave. Thereby, it is possible to improve the quality of the reception signal corresponding to each equal-frequency surface.

[0170] In addition, as referred to in Figure 12As described in (a) and (b) thereof, the received signal processing unit 133 is configured to extract a received signal based on a reflected wave from an equiphase surface corresponding to the frequency, based on the frequency component of the received signal. Thereby, an equiphase received signal corresponding to each equiphase surface can be obtained smoothly.

[0171] In addition, as Figure 10 shown, the received beam RB1 generated based on the received signals generated by the respective received wave elements 31a intersects with the transmitted beam TB1 generated by the first transmitted wave array 11. Thereby, in the range where the received beam RB1 intersects with the transmitted beam TB1 (equiphase surface), the distribution of the intensity data based on the intensity of the reflected wave can be calculated. Thereby, by changing the pointing direction of the received beam within the detection range through beamforming, the intensity data distributed in a three-dimensional shape within the detection range can be constituted.

[0172] <Change Example>

[0173] The present invention is not limited to the above-described embodiment. In addition, various changes can be made to the embodiment of the present invention in addition to the above-described configuration.

[0174] For example, in the above-described embodiment, as Figure 12 shown in (a) and (b) thereof, after extracting the frequency components of each frequency from the received signal, the signals are separated into signals in each azimuth by the beamforming process. However, the received signal may be separated into signals in each azimuth by the beamforming process first, and then the frequency components of each frequency may be extracted for the separated signals in each azimuth. That is, the Figure 12 band-pass filter 203 in (a) thereof and the beam combining unit 204 may be interchanged. In addition, the Figure 12 FFT 211 and the frequency extraction unit 212 in (b) thereof and the beam combining unit 204 may be interchanged.

[0175] In addition, in the above-described embodiment, as Figure 10 shown, a plurality of received wave elements 31a are provided, but the reflected wave may be received by only one received wave element 31a. However, in this case, the intensity data of the received signal cannot be distinguished for each azimuth and mapped onto the equiphase surface, so the state of the detection range cannot be displayed in a three-dimensional shape by an image as in the above-described embodiment. In this configuration, the azimuth of the received beam ( Figure 10 azimuth of θ1 thereof) is fixed. By extracting the frequency components of the received signal from the received beam in this azimuth, the intensity data in each direction in the vertical direction can be obtained. Thereby, by mapping the intensity data in each direction in the vertical direction, a two-dimensional detection image can be displayed.

[0176] In addition, in the above-described embodiment, the first transmission signal S11 and the second transmission signal S12 are the same signal. However, as long as useless frequency components of the transmitted wave can be suppressed, the first transmission signal S11 and the second transmission signal S12 may also be mutually different signals. In addition, in the above-described embodiment, the carrier frequencies of the transmission signal S1, the first transmission signal S11, and the second transmission signal S12 are constant. However, the carrier signal may be frequency-modulated like a chirp signal. In addition, the first transmission signal S11 may be a burst wave, and the second transmission signal S12 may also be a burst wave.

[0177] In addition, the timing for switching the supply destination to the first transmission wave element 11a that is the supply destination of the first transmission signal S11 and the timing for switching the supply destination to the second transmission wave element 12a that is the supply destination of the second transmission signal S12 are not limited to the timings described in (a) and (b) of Figure 13 As long as useless frequency components generated in the transmitted wave can be suppressed, other timings may also be used.

[0178] In addition, the configurations of the first transmission wave array 11 and the second transmission wave array 12 are not limited to the configurations of the above-described embodiment. As long as a change in the frequency based on the Doppler effect can be generated in the transmission beam TB1, other configurations may also be used.

[0179] For example, as shown in (a) of Figure 15 the first transmission wave array 11 and the second transmission wave array 12 may be configured such that the second transmission wave element 12a is located on the side of the boundary between two adjacent first transmission wave elements 11a. In this case, the first transmission signal S11 and the second transmission signal S12 are supplied to each of the first transmission wave elements 11a and the second transmission wave elements 12a at the same timing as in the case of Figure 10 Thereby, useless frequency components generated in the transmitted wave can be suppressed.

[0180] In addition, as shown in (b) of Figure 15 it may be configured to group a plurality of transmission wave elements 10a into a plurality of groups and switch the supply destination of the transmission signal S1 between the groups. According to this configuration, the transmission wave source can also be moved in the moving direction D1, and thus a change in the frequency based on the Doppler effect can be generated in the transmission beam TB1. In addition, since the transmitted wave is transmitted for each group, the output of the transmitted wave can be increased. The number of grouped transmission wave elements 10a is not limited to two and may be three or more.

[0181] In addition, the number of transmitting wave elements is not limited to the number shown in the above-described embodiment, and as long as there are a plurality of them, other numbers are also possible. Further, in the above-described embodiment, the transmitting wave array and the receiving wave array are arranged perpendicular to each other, but the transmitting wave array and the receiving wave array may also be arranged at an angle slightly deviated from the perpendicular.

[0182] In addition, Figure 11 shows the configuration in the case of using the first transmitting wave array 11 and the second transmitting wave array 12, but it may also be configured to use only the first transmitting wave array 11. In this case, the second transmitting wave array 12, the second transmission signal generation unit 121, the second transmitting amplifier 122, and the second signal switching unit 123 are omitted from Figure 11 .

[0183] Furthermore, Figure 14 shows the configuration in the case where the target detection device 1 (sonar, radar) is arranged on the ship 2, but the target detection device 1 (sonar, radar) may also be provided on a moving body other than the ship 2, or the target detection device 1 (sonar, radar) may be provided on a structure other than a moving body such as a buoy.

[0184] <Second Embodiment>

[0185] In the above-described embodiment, by driving (scanning) the plurality of transmitting wave elements of the transmitting wave array only once from top to bottom, a transmitting wave of one pulse amount corresponding to one detection unit (1 ping) is transmitted. In this case, in each transmitting wave element, the transmitting wave is transmitted only during the period when the transmitting wave element is driven. Therefore, the transmission energy of one pulse is low, and the maximum detectable distance is limited.

[0186] Then, in the second embodiment, control is performed to increase the transmission energy of one pulse. Specifically, in one detection unit, using the method described with reference to Figure 4 , scanning is performed in which the plurality of first transmitting wave elements 11a of the first transmitting wave array 11 and the plurality of second transmitting wave elements 12a of the second transmitting wave array 12 are continuously driven in one direction a plurality of times to generate a pulse. More specifically, in the configuration of Figure 4 , the signal switching units 21 and 22 are controlled such that in the first timing, for the plurality of transmitting wave elements 11a and 12a between the start element and the end element, a transmission signal is continuously supplied from the start element to the end element, and are controlled such that in the second timing following the first timing, for the plurality of first transmitting wave elements 11a and 12a between the start element and the end element, a transmission signal is continuously supplied from the start element to the end element. Thereby, the transmission energy of one pulse can be increased.

[0187] Figure 16is a diagram schematically showing the state of the sound field when the first transmission wave array 11 and the second transmission wave array 12 are scanned in one direction multiple times. In Figure 16 the arrangement directions of the first transmission wave elements 11a and the second transmission wave elements 12a in the first transmission wave array 11 and the second transmission wave array 12, and the front directions of the first transmission wave array 11 and the second transmission wave array 12 are set as the x-axis and the y-axis, respectively. Also, in Figure 16 the wavefront of the sound field is shown.

[0188] Control is performed such that after the multiple first transmission wave elements 11a and the second transmission wave elements 12a of the first transmission wave array 11 and the second transmission wave array 12 are driven continuously in sequence from one end (the transmission wave element at the start position) to the other end (the transmission wave element at the end position), and after the first transmission wave array 11 and the second transmission wave array 12 are scanned, the same scan is repeated without an interval in time. Thus, the following state is formed: after the sound source S transmitting at the frequency f0 moves from the start position to the end position, without an interval in time, the sound source S moves from the start position to the end position again. By repeating this control a specified number of times in one detection unit, the transmission time of the pulse is extended and the transmission energy increases. In Figure 16 for convenience, the sound field in the case of performing 4 scans in one detection unit is shown.

[0189] In addition, in the following description, it is assumed that there is no discontinuity in the sound wave in each azimuth as shown in Figure 1 (a). That is, Figure 1 the influence of the discontinuity of the sound wave as shown in Figure 4 (b) is suppressed by the control using the first transmission wave array 11 and the second transmission wave array 12, and furthermore, Figure 8 the influence of spurious (useless peaks) as shown in Figure 12 (a) and Figure 12 (c) is eliminated by the frequency filtering performed by the band-pass filter 203 shown in Figure 1 (a) or the frequency extraction unit 212 shown in

[0190] (b). Therefore, when the first transmission wave array 11 and the second transmission wave array 12 transmit waves, by applying this frequency filtering in the receiving system, it can also be regarded as equivalent to the state where the continuity of the sound wave is maintained in all azimuths as shown in Figure 16As shown, the transmitted packets of each scan are time-compressed and the carrier frequency changes according to the azimuth θ in the in-plane direction of the x-y plane with respect to the front direction (hereinafter referred to as "azimuth θ" in Embodiment 2). In addition, corresponding to this time compression, a gap corresponding to the azimuth θ (a section where the sound pressure is zero) is generated between the transmitted packets. In Figure 16 the transmitted packets in the front direction (y-axis direction) and the scan direction (x-axis direction) of the first transmitted wave array 11 and the second transmitted wave array 12 are shown along the y-axis and the x-axis respectively, and the transmitted packet in the azimuth of the arrow is shown at the tip of the arrow. The τ given to each transmitted packet is the period during which the sound source S moves from the start position to the end position, that is, the period of one scan for the first transmitted wave array 11 and the second transmitted wave array 12.

[0191] As Figure 16 shown, in the front direction (y-axis direction), since there is no Doppler effect, the waveform of the transmitted packet can maintain the same waveform as the transmitted signal. Therefore, in the front direction, no gap is generated between the transmitted packets. In contrast, in the scan direction (x-axis direction) of the first transmitted wave array 11 and the second transmitted wave array 12, the waveform of the transmitted packet is greatly compressed due to the Doppler effect, and a large gap is generated between the transmitted packets. In addition, in the azimuth of the arrow, the Doppler effect is smaller than in the x-axis direction, so the compression of the waveform of the transmitted packet is smaller, suppressing the gap generated between the transmitted packets.

[0192] In this way, the compression of the waveform and the state of the gap are different for each azimuth, so the sound wave spectrum is different for each azimuth. That is, the spectral intensity is low in the azimuth where phase discontinuity is generated due to the gap, and the spectral intensity is high in the azimuth where phase discontinuity is not generated due to the gap. Specifically, in the azimuth where the gap is an integer multiple of the wavelength, no phase discontinuity is generated, so the spectral intensity is high.

[0193] Figure 17 The (a) and (b) in

[0194] are diagrams showing the simulation results obtained by simulating the relationship between the spectrum of the sound field and the azimuth.

[0195] Transmission frequency: f0 = 150 kHz

[0196] Pulse width: PW = 100 msec

[0197] Scan period: τ = 1 msec

[0198] That is, a continuous wave CW with a constant transmission frequency f0 is transmitted in each transmitted packet. The scan period τ of each transmitted packet is set to 1 msec, and the sound source S is scanned 100 times to form a pulse. That is, the pulse width PW is 100 msec.

[0199] Figure 17 (a) of Figure 17 is the simulation result based on 3D contour display, and (b) of

[0200] is the 3D bird's-eye view from the azimuth axis direction. Figure 17 Referring to (a) and (b) of

[0201] it can be seen that peaks of spectral intensity are formed at 1 kHz intervals, that is, transmission beams. The mechanism is as follows.

[0202] [Equation 1]

[0203] The number of waves transmitted in the forward direction (θ = 0) in one scan is f0·τ, and its packet is repeated during the scan period τ. CW waves with a long pulse width whose phases are connected are transmitted in the forward direction. On the other hand, in directions other than the forward direction, phase discontinuities due to gaps occur corresponding to the azimuth, but the initial phase between packets is maintained in the direction of the carrier frequency that satisfies the following relational expression.

[0204] As long as the period of the gap, that is, the period during which the phase stops, is an integer multiple of the period of the carrier wave in this direction, the initial phase between packets becomes the same and the influence of the gap is slight. This condition can be expressed by the following equation according to the above formula (1).

[0205] [Equation 2]

[0206]

[0207] According to Equation (2), it can be explained that in (a) and (b) of Figure 17 directions in which continuous phases, that is, spectra become sharp, are formed at every 1 / τ, that is, 1 kHz.

[0208] Next, the beam interval (interval between formed transmission beams) will be discussed.

[0209] The azimuth in which the transmission beam is formed is, as described above, the azimuth in which the initial phases are connected and is the azimuth in which the carrier frequency satisfies Equation (2). This azimuth θn is related to other variables by the following equation.

[0210] The time of the gap in the θ direction is obtained by the following equation.

[0211] [Equation 3]

[0212]

[0213] Here, V is the moving speed of the sound source S, c is the speed of sound, and r(θ) is the compression ratio of the transmitted wave propagating in the θ direction.

[0214] The azimuth at which the time of this gap becomes an integer multiple of the period of the carrier frequency in the θ direction is θn, and thus θn is defined by the following equation.

[0215] [Equation 4]

[0216]

[0217] Thus, θn can be obtained from the following equation.

[0218] [Equation 5]

[0219]

[0220] Therefore, a transmission beam is formed at the azimuth θn obtained from the above equation (5). Thus, by Figure 12 the band-pass filter 203 of (a) or Figure 12 the frequency extraction unit 212 of (b) extracts the carrier frequency of the azimuth θn, and the received signal corresponding to each transmission beam can be extracted.

[0221] <Third Embodiment>

[0222] Referring to Figure 17 of (b), for continuously making the detection range an image in the θ direction, the beam interval of the transmission beam is too wide. That is, in the angular range between the transmission beams, the received signal is missing, and it is difficult to generate a good detection image. Therefore, in the third embodiment, control is performed to further form a transmission beam between the transmission beams of Figure 17 of (b).

[0223] At the azimuth in the middle of the azimuths of adjacent transmission beams, the phase is reversed for each transmission packet. Therefore, by reversing the polarity of the transmission signal for each transmission packet and performing transmission, it should be phase-modulated to the initial phase at this azimuth.

[0224] Figure 18 of (a) and (b) are diagrams showing the simulation results obtained by simulating the relationship between the spectrum of the sound field and the azimuth when the polarity of the transmission signal is reversed for each transmission packet and transmitted. The simulation conditions are the same as those of Figure 17 of (a) and (b) except that the polarity of the transmission signal is reversed for each transmission packet.

[0225] Referring to Figure 18 of (a) and (b), a transmission beam is formed at the azimuth in the middle of the transmission beams of Figure 17 of (a) and (b). That is, in Figure 18 of (a) and (b), it can be seen that there is a formation of Figure 17A transmission beam that interpolates the azimuth between the transmission beams of (a) and (b) thereof. Thus, for example, in one detection unit, by performing a first transmission process of repeatedly transmitting a transmission packet without inverting the polarity for each transmission packet, and a second transmission process of repeatedly transmitting a transmission packet while inverting the polarity for each transmission packet, it is possible to complementarily interpolate the missing azimuth of the transmission beam by each transmission process, and it is possible to continuously make the detection range an image in the θ direction. In this case, by applying the carrier frequency of each transmission beam to the Figure 12 band-pass filter 203 of (a) thereof or Figure 12 the frequency extraction unit 212 of (b) thereof, it is also possible to extract the received signal corresponding to each transmission beam.

[0226] In addition, in the first transmission process and the second transmission process, it is only necessary to invert the polarity of the signal in either the odd-numbered or the even-numbered ones. Thus, by each transmission process, it is possible to complementarily interpolate the missing azimuth of the transmission beam.

[0227] <Fourth Embodiment>

[0228] In the above-described Embodiment 3, if the first transmission process and the second transmission process are divided into two transmissions and receptions, the frame rate is halved. On the other hand, in the case of simultaneously performing the first transmission process and the second transmission process, since the transmission packets with inverted polarities between the transmission processes interfere with each other, the transmission wave disappears. Therefore, simultaneously performing the first transmission process and the second transmission process is equivalent to stopping the transmission in the odd-numbered or even-numbered transmission packets. Thus, in the fourth embodiment, it is considered to stop the transmission in the odd-numbered or even-numbered transmission packets.

[0229] According to the above formula (2), it can be seen that by repeatedly transmitting with a period of 2τ that is twice the scanning period τ, the interval between the transmission beams can be halved. In this case, for example, by Figure 16 among the series of transmission packets shown, only transmitting the even-numbered or odd-numbered transmission packets, the scanning period becomes twice. Therefore, if only the even-numbered or odd-numbered transmission packets are transmitted in this way, it should be possible to halve the interval between the transmission beams.

[0230] Figure 19 (a) and (b) thereof are diagrams showing the simulation results obtained by simulating the relationship between the spectrum of the sound field and the azimuth in the case of only transmitting the even-numbered transmission packets. The simulation conditions are the same as those of (a) and (b) of Figure 17 except for only transmitting the even-numbered transmission packets.

[0231] Referring to Figure 19 (a) and (b) thereof, it can be seen that compared with Figure 17Compared with the cases of (a) and (b), the interval between the transmission beams is halved. Thus, by controlling the first transmission wave array 11 and the second transmission wave array 12 to transmit only the even-numbered or odd-numbered transmission packets, the interval between the transmission beams can be narrowed. That is, by transmitting only the even-numbered or odd-numbered transmission packets, it is possible to suppress the pulse width of the pulses transmitted in one detection unit and improve the range resolution, while narrowing the interval between the transmission beams. Thereby, it is possible to continuously form a detection range into an image in the θ direction.

[0232] In addition, according to the fourth embodiment, since the information of one detection unit can be obtained in one transmission and reception, the frame rate when generating a detection image can be improved. Further, in the case where a low frame rate is acceptable, the first transmission process and the second transmission process may be divided into two transmissions and receptions as described in the above third embodiment.

[0233] Furthermore, it is also possible to continuously perform the first transmission process and the second transmission process without a gap and obtain the information of one detection unit in one transmission and reception.

[0234] <Fifth Embodiment>

[0235] As in the second embodiment described above, if the transmission packets are repeatedly transmitted multiple times in one detection unit, the transmission energy increases and the S / N ratio rises. However, conversely, the transmission period (pulse width) in one detection unit becomes long, so there is a problem of reduced range resolution. Thus, in the fifth embodiment, pulse compression is investigated to improve the range resolution.

[0236] The inventors of the present application verified through simulation the sound field in the case where a sound source S of a linear chirp (LFM) signal with a transmission pulse width of 100 msec and a chirp sweep width of 1 kHz moves uniformly at a speed V from a start position to an end position repeatedly. In this verification, the parameters of the linear chirp (LFM) signal are set as follows.

[0237] <Parameters of LFM>

[0238] Sweep start frequency: fs = 150 kHz

[0239] Sweep frequency: fsweep = 1 kHz

[0240] Sweep time (LFM pulse width) = 100 msec

[0241] Window function: Hanning (applied to a 100-msec pulse)

[0242] Sound source sweep length: L = 16λo (λo: wavelength at the sweep start frequency)

[0243] Sound source sweep time (during scanning): τ = 1 msec

[0244] That is, a signal obtained by slicing a linear chirp signal whose frequency linearly shifts from 150 kHz to 151 kHz within 100 msec at every 1 msec is used to drive the transmission wave array to transmit a transmission wave with a pulse quantity of 1.

[0245] Figure 20 Figures (a) and (b) are diagrams showing simulation results obtained by analogously obtaining the relationship between the spectrum and azimuth of the sound field in the case of transmission using the linear chirp signal under the above conditions.

[0246] As Figure 20 shown in Figures (a) and (b), in the case of transmission using the linear chirp signal under the above conditions, transmission beams are also formed at intervals roughly the same as those in Figure 17 Figures (a) and (b).

[0247] Next, in order to verify the time response after pulse compression, the autocorrelation functions of the azimuths where the transmission beams are formed in Figure 20 Figures (a) and (b) are obtained.

[0248] Figure 21 Figures (a) and (b) are respectively graphs showing the autocorrelation functions of the azimuth 0°, Figure 21 and Figures (c) and (d) are respectively graphs showing the autocorrelation functions of the azimuth 7°. Figure 21 Figures (b) and (d) respectively show an enlarged view of the region from 1 to 4000 μsec in the graphs of Figure 21 Figures (a) and (c).

[0249] According to Figure 21 the results shown in Figures (a) to (d), by using the transmission waveform of the transmission beam azimuth as the compression filter coefficient, good pulse compression with few time-axis side lobes can be performed. In Figure 21 Figures (a) to (d), a pulse width of 100 msec is compressed to about 3 msec. Therefore, by further providing a compression filter with coefficients corresponding to the transmission waveforms of the transmission beams in each azimuth in the Figure 11 reception signal processing unit 133 that processes the reception signal, the range resolution at the azimuth of each transmission beam can be improved.

[0250] Furthermore, in the present embodiment, the interval between the transmission beams is also wide as in the second embodiment above. Therefore, in order to further interpolate the transmission beams in this interval, the method of inverting the polarity for each transmission packet is also explored in the same way as in the third embodiment above.

[0251] Figure 22Figs. (a) and (b) are diagrams showing simulation results obtained by simulating the relationship between the spectrum and azimuth of the sound field when transmitting using a linear chirp signal under the above conditions.

[0252] In this simulation, under the simulation conditions of Figure 20 Figs. (a) and (b), the polarity of the linear chirp signal is reversed for each scanning period τ. Other simulation conditions are the same as those of Figure 20 Figs. (a) and (b).

[0253] Referring to Figure 22 Figs. (a) and (b), it can be seen that there are transmitting beams that interpolate the azimuth between adjacent transmitting beams of Figure 20 Figs. (a) and (b). Thus, by combining the first transmission process of transmitting waves using a linear chirp signal with its polarity reversed for each scanning period τ and the second transmission process of transmitting waves using a linear chirp signal with its polarity not reversed for each scanning period τ, it is possible to complementarily interpolate the azimuth between the transmitting beams through each transmission process. Thus, it is possible to continuously form an image of the detection range in the θ direction.

[0254] Figure 23 Figs. (a) and (b) are respectively graphs showing the autocorrelation functions of the azimuth of the transmitting beams formed in Figure 22 Figs. (a) and (b), Figure 23 Figs. (c) and (d) are respectively graphs showing the autocorrelation functions of the azimuth of the transmitting beams formed in Figure 22 Figs. (a) and (b). Figure 23 Figs. (b) and (d) respectively show an enlarged view of the region of 1 - 4000 μsec in the graphs of Figure 23 Figs. (a) and (c).

[0255] From the results shown in Figure 23 Figs. (a) - (d) as well, similar to Figure 21 Figs. (a) - (d), by using the transmission waveform of the transmitting beam azimuth as the compression filter coefficient, good pulse compression with few time - axis sidelobes can be performed. In Figure 23 Figs. (a) - (d), the pulse width of 100 msec is also compressed to about 3 msec. Therefore, in this case as well, similar to the above, by using a compression filter, the range resolution at the azimuth of each transmitting beam can be improved.

[0256] Furthermore, in the fifth embodiment, similar to the fourth embodiment, instead of continuously controlling the first transmission process and the second transmission process, it is also possible to control the transmission of only the odd - numbered or even - numbered transmission packets (scanning periods).

[0257] <Sixth Embodiment>

[0258] In the above-described Second to Fourth Embodiments, the scanning of all transmitted packets is performed only in one direction. However, the scanning direction of the transmitted packets is not limited to this. In the Sixth Embodiment, the moving direction of the sound source S, that is, the scanning direction, is reversed for odd-numbered transmitted packets compared to even-numbered transmitted packets.

[0259] In this case, after scanning the sound source S in one direction, without an intervening time gap, the sound source S is scanned in the opposite direction. That is, the sound source S is moved back and forth multiple times. Specifically, for the first transmission wave array 11 and the second transmission wave array 12, the transmission wave elements are sequentially and continuously driven from one end of the transmission wave elements to the other end, and then, without an intervening time gap, the transmission wave elements are sequentially and continuously driven from the other end of the transmission wave elements to one end.

[0260] Figure 24 It is a diagram schematically showing the state of the sound field when the first transmission wave array 11 and the second transmission wave array 12 are scanned back and forth multiple times.

[0261] The transmitted packets of each scan are time-compressed corresponding to the azimuth θ and the carrier frequency changes. In addition, since the scanning direction of odd-numbered transmitted packets is opposite to that of even-numbered transmitted packets, the compression ratios of odd-numbered and even-numbered transmitted packets are different. If the speed of each scan is set to V odd 、V even , then the compression ratios r odd (θ) and r even (θ) are expressed by the following equations.

[0262] [Equation 6]

[0263]

[0264] [Equation 7]

[0265]

[0266] According to Figure 24 and the above-described equations (6) and (7), it can be seen that compression and expansion alternate at the azimuth θ.

[0267] Furthermore, the transmission frequencies of odd-numbered transmitted packets and even-numbered transmitted packets can also be different from each other. In this case, the transmission frequencies of odd-numbered transmitted packets and even-numbered transmitted packets are respectively set to frequencies that do not affect the transmission of the other transmitted packets.

[0268] Figure 25This is a diagram showing the simulation results obtained by using simulation to represent the relationship between the spectrum and azimuth of the sound field in the case of performing 10 round-trip scans with the transmission frequency of odd-numbered transmission packets changed compared to that of even-numbered transmission packets.

[0269] The simulation conditions are as follows.

[0270] Sound source sweep length: L = 16λo (λo: wavelength at 150 kHz)

[0271] Scanning time (per scan): τ = 1 msec

[0272] Odd-numbered transmission packets: f0 = 150 kHz, V even = 160 msec

[0273] Even-numbered transmission packets: f0 = 170 kHz, V odd = 160 msec

[0274] Under the above conditions, the sound source S makes 10 round trips. That is, the odd-numbered transmission packets are formed by the movement of the sound source S along the forward path, and the even-numbered transmission packets are formed by the movement of the sound source S along the return path. The moving speeds of the sound source S on the forward path and the return path are set to be the same.

[0275] As Figure 25 shown, it can be seen that there are two frequency components in one azimuth. In Embodiment 6, similar to the above-described Second to Fifth Embodiments, by separating the frequencies by a band-pass filter (or a compression filter) and FFT, the received signals in each azimuth can be obtained.

[0276] In addition, in this transmission method, since the frequencies during the odd-numbered transmission packets and the even-numbered transmission packets are separated, similar to the above-described Fourth Embodiment, the transmission period of the odd-numbered transmission packets becomes longer and the interval between the transmission beams becomes narrower. Similarly, the transmission period of the even-numbered transmission packets also becomes longer and the interval between the transmission beams becomes narrower. Thus, the interval between the transmission beams can be shortened, and the detection range can be continuously made into an image in the θ direction.

[0277] In the Sixth Embodiment, transmission is also performed on the transmission packets that are stopped from being transmitted in the Fourth Embodiment, so the transmission energy of the pulses in one detection unit can be significantly increased.

[0278] In addition, in Figure 25In the simulation, the sound source S is moved back and forth. However, it is also possible that the moving direction of the sound source S, i.e., the scanning direction of the transmission packet, is the same for the odd-numbered transmission packets and the even-numbered transmission packets. In this case, it is only necessary to set the transmission frequencies of the odd-numbered transmission packets and the even-numbered transmission packets to frequencies that do not affect the transmission of the other transmission packets. Thus, a frequency spectrum including two frequency components in one azimuth can be formed, and the transmission energy of the pulses in one detection unit can be significantly increased.

[0279] In addition, in the sixth embodiment, similar to the fifth embodiment, a chirp signal can also be used as the transmission signal to perform pulse compression.

[0280] Description of reference numerals:

[0281] 1 Target detection device

[0282] 11 First transmission wave array

[0283] 11a First transmission wave element

[0284] 12 Second transmission wave array

[0285] 12a Second transmission wave element

[0286] 31 Reception wave array

[0287] 31a Reception wave element

[0288] 101 Control unit

[0289] 111 First transmission signal generation unit

[0290] 113 First signal switching unit

[0291] 121 Second transmission signal generation unit

[0292] 123 Second signal switching unit

[0293] 133 Reception signal processing unit

[0294] S11 First transmission signal

[0295] S12 Second transmission signal

[0296] EP1 to EP5 Equi-frequency surfaces

[0297] [Terms]

[0298] Not all of the objectives or effects / advantages may be achieved in accordance with any particular embodiment described in this specification. Thus, for example, those skilled in the art can conceive that a particular embodiment can be configured to operate in a manner that achieves or optimizes one or more effects / advantages taught in this specification, but may not necessarily achieve other objectives or effects / advantages taught or suggested in this specification.

[0299] All of the processes described in this specification can be specifically implemented by software code modules executed by a computing system including one or more computers or processors and be fully automated. The code modules can be stored in any type of non-volatile computer-readable medium or other computer storage device. Part or all of the methods can be specifically implemented using dedicated computer hardware.

[0300] There are many other variations in addition to the ways described in this specification, which are obvious from this disclosure. For example, according to an embodiment, any particular action, event, or function of the algorithms described in this specification can be executed in a different time sequence, can be added, combined, or completely excluded (e.g., not all of the described behaviors or events are necessary for the execution of the algorithm). Further, in a particular embodiment, actions or events can be executed not sequentially (in order) but concurrently (in parallel) through, for example, multi-threading processing, interrupt processing, or multiple processors or processor cores, or on other parallel architectures. Further, different tasks or processes can also be executed by different machines and / or computing systems that can function together.

[0301] The various illustrative logical modules and units described in connection with the embodiments disclosed in this specification can be implemented or executed by a machine such as a processor. The processor can be a microprocessor, but alternatively, the processor is a controller, a microcontroller, or a state machine, or a combination thereof, etc. The processor can include an electrical circuit configured to process computer-executable instructions. In other embodiments, the processor includes an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable devices that perform logical operations without processing computer-executable instructions. The processor can also be installed as a combination of computing devices, such as a combination of a digital signal processor (digital signal processing device) and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration. In this specification, the description is mainly about digital technology, but the processor can also mainly include analog components. For example, part or all of the signal processing algorithms described in this specification can be implemented by an analog circuit or an analog-digital hybrid circuit. The computing environment includes a computer system based on a microprocessor, a mainframe computer, a digital signal processor, a portable computing device, a device controller, or a computing engine within a device, but can include any type of computer system not limited thereto.

[0302] Unless otherwise specified, conditional words such as "can", "be able to", "may", or "have the possibility" should be understood in the context generally used to convey that "a particular embodiment includes a particular feature, element, and / or step, but other embodiments do not". Therefore, such conditional words generally do not indicate that the feature, element, and / or step is a necessary method in one or more embodiments, or that one or more embodiments necessarily include the logic for determining whether these features, elements, and / or steps are included in any particular embodiment or whether they are executed.

[0303] Selective language such as the phrase "at least one of X, Y, Z" should be understood in the context generally used to indicate that an item, term, etc. can be any one of X, Y, Z or any combination thereof (e.g., X, Y, Z). Therefore, such selective words generally do not indicate that a particular embodiment requires each of at least one of X, at least one of Y, or at least one of Z to exist separately.

[0304] Any process description, element, or module in the flowcharts described in this specification and / or shown in the drawings should be understood as an object that potentially represents a part of a module, segment, or code, including one or more executable commands for implementing specific logical functions or elements in the process. Alternative embodiments are included within the scope of the embodiments described in this specification, where elements or functions can be deleted from or executed in a different order from the illustrated or described content, substantially simultaneously or in the reverse order, as understood by those skilled in the art according to the associated functionality.

[0305] Unless otherwise explicitly stated, numerals such as "a" generally should be interpreted to mean: including one or more of the described items. Thus, statements such as "a device configured in a certain manner" mean including one or more of the enumerated devices. Such one or more enumerated devices can also be collectively configured in a manner to execute the recited reference content. For example, "a processor configured to execute the following A, B, and C" can include a first processor configured to execute A and a second processor configured to execute B and C. Moreover, even if specific numbers of the introduced embodiments are explicitly enumerated, those skilled in the art should interpret such enumerations typically to mean at least the enumerated numbers (e.g., a simple enumeration of "enumerating two" without using other modifiers generally means enumerating at least two, or enumerating two or more).

[0306] Generally, the terms used in this specification are generally judged by those skilled in the art to be "non-limiting" terms (e.g., a term such as "comprising..." should be interpreted as "more than this, at least comprising...", a term such as "having..." should be interpreted as "at least having...", a term such as "including" should be interpreted as "including the following, but not limited thereto", etc.).

[0307] For the purpose of illustration, a term such as "horizontal" in this specification is defined in terms of the plane of the bottom surface of the area where the system for illustration is used or a plane parallel to the surface, or the plane where the method for illustration is implemented, regardless of its direction. A term such as "bottom surface" can be replaced with a term such as "ground surface" or "water surface". A term such as "vertical / plumb" refers to a direction perpendicular / plumb to the defined horizontal line. Terms such as "upper side", "lower side", "below", "above", "side surface", "higher", "lower", "above", "over...", "under" are defined with respect to the horizontal plane.

[0308] As used in this specification, terms such as "attach", "connect", "paired", and other related terms, unless otherwise noted, should be interpreted to include detachable, movable, fixed, adjustable, and / or detachable connections or couplings. Connections / couplings include direct connections and / or connections having intermediate structures between the two components described.

[0309] Unless otherwise expressly stated, numbers following terms such as "about", "substantially", and "essentially" as used in this specification include the recited numbers, and further represent amounts that are close to the recited amounts for performing the desired function or achieving the desired result. For example, "about", "substantially", and "essentially", unless otherwise expressly stated, refer to values less than 10% of the recited value. As used in this specification, features of the embodiments disclosed after terms such as "about", "substantially", and "essentially" further represent several variable features for performing the desired function or achieving the desired result with respect to that feature.

[0310] In the above embodiments, many variations and modifications can be added, and these elements should be understood to be included in other permissible examples. All such modifications and variations are intended to be included within the scope of this disclosure and are protected by the following claims.

Claims

1. A target detection device, comprising: A first transmission signal generation unit that generates a first transmission signal; A first transmission wave array having a plurality of first transmission wave elements that convert the first transmission signal into transmission waves; A first signal switching unit that supplies the first transmission signal to one of the first transmission wave elements in the first transmission wave array; A control unit that controls the first signal switching unit to switch the first transmission wave element supplied with the first transmission signal from a first element to a second element at a first timing; A second transmission signal generation unit that generates a second transmission signal; A second transmission wave array having a plurality of second transmission wave elements that convert the second transmission signal into transmission waves; and A second signal switching unit that supplies the second transmission signal to one of the second transmission wave elements in the second transmission wave array, The control unit further controls the second signal switching unit to switch the second transmission wave element supplied with the second transmission signal from a first element of the second transmission wave array to a second element of the second transmission wave array at a third timing after the first timing, The control unit controls the first signal switching unit to switch the first transmission wave element supplied with the first transmission signal from a second element of the first transmission wave array to a third element of the first transmission wave array at a second timing after the first timing and the third timing, The control unit controls such that when the first signal switching unit switches the first transmission wave element supplied with the first transmission signal, the second transmission signal is supplied to one of the second transmission wave elements in the second transmission wave array.

2. The target detection device according to claim 1, In the first transmission wave array, a second element of the first transmission wave array is adjacent to a first element of the first transmission wave array.

3. The target detection device according to claim 1 or 2, The carrier wave of the first transmission signal is a single frequency.

4. The target detection device according to claim 1 or 2, The carrier wave of the first transmission signal is a modulated signal.

5. The target detection device according to claim 1, The plurality of first transmission wave elements are grouped into a plurality of groups, and in each group, the plurality of first transmission wave elements are connected, The first signal switching unit has a configuration that supplies the first transmission signal to one of the groups in the first transmission wave array, The control unit controls the first signal switching unit to switch the group supplied with the first transmission signal from a first group to a second group at the first timing.

6. The target detection device according to claim 1, In the second transmission wave array, a second element of the second transmission wave array is adjacent to a first element of the second transmission wave array, The first element of the first transmission wave array is adjacent to the first element of the second transmission wave array.

7. The target detection device according to claim 1, The carrier wave of the second transmission signal is a single frequency.

8. The target detection device according to claim 1, The carrier wave of the second transmission signal is a modulated signal.

9. The target detection device according to claim 1, the first transmission signal generation unit modulates the amplitude of the first transmission signal, the second transmission signal generation unit modulates the amplitude of the second transmission signal.

10. The target detection device according to claim 1, the frequency of the carrier wave of the second transmission signal is the same as the frequency of the carrier wave of the first transmission signal.

11. The target detection device according to claim 1 or 2, further comprising: a reception wave array including at least one reception wave element that receives a reflected wave generated by reflection of the transmission wave on a target and converts the reflected wave into a reception signal.

12. The target detection device according to claim 11, further comprising: a reception signal processing unit that processes the reception signal, the reception signal processing unit extracts an equal-frequency reception signal based on the frequency component of the reception signal, and the equal-frequency reception signal is based on the reflected wave from an equal-frequency plane corresponding to the frequency component.

13. The target detection device according to claim 12, the reception signal processing unit obtains the equal-frequency reception signal of the equal-frequency plane corresponding to each frequency by extracting a plurality of frequency components respectively extracted at different frequencies from the reception signal.

14. The target detection device according to claim 12, the reception signal processing unit calculates the spectrum of the reception signal, the reception signal processing unit obtains the equal-frequency reception signal of the equal-frequency plane corresponding to each frequency based on the spectrum.

15. The target detection device according to claim 12, the reception wave array includes a plurality of reception wave elements, the reception signal processing unit performs beamforming based on the reception signals generated by the respective reception wave elements, and calculates the arrival direction of the reflected wave from the target based on the beamforming.

16. The target detection device according to claim 11, the reception wave array includes a plurality of reception wave elements, the reception wave array is different from the first transmission wave array, the reception beam generated based on the reception signals generated by the respective reception wave elements intersects the transmission beam generated by the first transmission wave array.

17. The target detection device according to claim 1 or 2, the target detection device is a sonar for detecting targets in water.

18. The target detection device according to claim 1 or 2, the target detection device is a radar for detecting targets in the air.

19. The target detection device according to claim 1 or 2, in the first time sequence, the first signal switching unit supplies the first transmission signal continuously from the start element to the end element for the plurality of first transmission wave elements between the start element and the end element as the first time sequence progresses, so as to supply the first transmission signal, In a second timing following the first timing, the first signal switching unit supplies the first transmission signal to the plurality of first transmission wave elements between the start element and the end element continuously from the start element to the end element as the second timing progresses, thereby supplying the first transmission signal.

20. The target detection device according to claim 19, The control unit switches the positions of the start element and the end element after the first timing and before the second timing.

21. The target detection device according to claim 1 or 2, The first element of the first transmission wave array is supplied with a first part of the first transmission signal, The second element of the first transmission wave array is supplied with a second part of the first transmission signal different from the first part.

22. A target detection method, Generate a first transmission signal, At a first timing, switch the supply of the first transmission signal from a first element in a first transmission wave array having a plurality of first transmission wave elements to a second element, Generate a second transmission signal, At a third timing after the first timing, switch the supply of the second transmission signal from a first element in a second transmission wave array having a plurality of second transmission wave elements to a second element, At a second timing after the first timing and the third timing, switch the supply of the first transmission signal from the second element in the first transmission wave array to a third element, When switching the first transmission wave element to which the first transmission signal is supplied, supply the second transmission signal to one of the second transmission wave elements in the second transmission wave array.

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