Radar device

Abstract

A radar device is provided that improves the accuracy of target detection. A receiving antenna includes a plurality of first antennas disposed at different positions in a first direction, a plurality of second antennas disposed at different positions in a second direction orthogonal to the first direction, and a third antenna different from the first antennas and second antennas. At least one of the plurality of first antennas overlaps with one of the plurality of second antennas. The third antenna is disposed at a position in the second direction different from the positions of the plurality of first antennas, and at a predetermined interval from the positions of the plurality of second antennas in the first direction. At least one interval between the plurality of first antennas is a predetermined interval. A transmitting antenna includes a plurality of fourth antennas disposed in the first direction and a plurality of fifth antennas disposed in the second direction. At least one of the plurality of fourth antennas overlaps with one of the plurality of fifth antennas. The interval between the plurality of fourth antennas in the first direction is greater than the aperture length of the plurality of first antennas.

Description

Technical Field

[0001] This disclosure relates to radar devices. Background Technology

[0002] In recent years, there has been a push for the use of radar devices that incorporate short-wavelength radar signals capable of transmitting high-resolution microwave or millimeter waves. Additionally, to improve safety when outdoors, there is a demand for radar devices that can detect small objects such as pedestrians in addition to vehicles (e.g., referred to as "wide-angle radar devices").

[0003] As a radar device with a wide-angle detection range, there is a structure that uses a method called Direction of Arrival (DOA) estimation, which receives reflected waves from a target (or object) through an array of antennas consisting of multiple antennas (or, also called "antenna elements") and estimates the direction of arrival (or "angle of arrival") of the reflected waves based on the received phase difference relative to the element spacing (antenna spacing).

[0004] For example, as a method for estimating the angle of arrival, the Fourier method (FFT) can be listed, or as a method that can obtain high resolution, the Capon method, MUSIC (Multiple Signal Classification), and ESPRIT (Estimation of Signal Parameters via Rotational Invariance Techniques) can be listed.

[0005] In addition, as a radar device, for example, a structure has been proposed that includes multiple antennas (array antennas) in addition to the radar receiver, and beam scanning is performed by using signal processing of the transceiver array antennas (for example, see Non-Patent Document 1).

[0006] Prior art literature

[0007] Patent documents

[0008] Patent Document 1: International Publication No. 2018 / 142396

[0009] Non-patent literature

[0010] Non-patent literature 1: J. Li, and P. Stoica, "MIMO Radar with Colocated Antennas", Signal Processing Magazine, IEEE Vol. 24, Issue: 5, pp. 106-114, 2007

[0011] Non-patent literature 2: Kazuo Shirakawa et al., “3D Scanning Millimeter-Wave Radar for Automotive Use”, Fujitsu Ten Technology Journal, Vol.30, No.1, 2012.

[0012] Non-patent literature 3: M. Kronauge, H. Rohling, "Fast two-dimensional CFAR procedure", IEEE Trans. Aerosp. Electron. Syst., 2013, 49, (3), pp. 1817-1823

[0013] Non-patent literature 4: Direction-of-arrival estimation using signal subspace modeling Cadzow, JA; Aerospace and Electronic Systems, IEEE Transactions on Volume: 28, Issue: 1 Publication Year: 1992, Page (s): 64-79

[0014] However, there is still room for research into methods to improve the angle measurement performance of radar devices (e.g., MIMO radar). Summary of the Invention

[0015] The non-limiting embodiments disclosed herein contribute to providing radar devices with improved angle measurement performance.

[0016] A radar device according to an embodiment of this disclosure includes: a transmitting circuit that uses a plurality of transmitting antennas to transmit a transmitting signal; and a receiving circuit that uses a plurality of receiving antennas to receive a reflected wave signal of the transmitted signal after reflection from an object. One of the transmitting antennas and the receiving antennas includes a plurality of first antennas disposed at different positions in a first direction, a plurality of second antennas disposed at different positions in a second direction orthogonal to the first direction, and a third antenna different from the first and second antennas. The first and second antennas include a repeating antenna. The third antenna is disposed at a position different from the configuration positions of the plurality of first antennas in the second direction and separated from the configuration positions of the plurality of second antennas in the first direction by a predetermined interval. At least one interval between the plurality of first antennas is the predetermined interval. The other of the plurality of transmitting antennas and the plurality of receiving antennas includes a plurality of fourth antennas disposed in the first direction and a plurality of fifth antennas disposed in the second direction. The plurality of fourth antennas and the plurality of fifth antennas include a repeating antenna. The interval between the plurality of fourth antennas in the first direction is greater than the aperture length of the plurality of first antennas.

[0017] Furthermore, these broad or specific embodiments can be implemented by systems, apparatuses, methods, integrated circuits, computer programs, or recording media, or by any combination of systems, apparatuses, methods, integrated circuits, computer programs, and recording media.

[0018] According to one embodiment of this disclosure, the angle measurement performance of a radar device can be improved.

[0019] Further advantages and effects of one embodiment of this disclosure will be clearly presented by the specification and accompanying drawings. These advantages and / or effects are provided by various embodiments and the features described in the specification and drawings, but not all of them need to be provided to obtain one or more of the same features. Attached Figure Description

[0020] Figure 1 This is a diagram illustrating an example configuration of the transmitting and receiving antennas and the virtual receiving array.

[0021] Figure 2 This is a diagram representing an example of the results of a computer simulation of the orientation estimation process.

[0022] Figure 3 This is a diagram illustrating an example configuration of the transmitting and receiving antennas and the virtual receiving array.

[0023] Figure 4 This is a diagram representing an example of the results of a computer simulation of the orientation estimation process.

[0024] Figure 5This is a block diagram illustrating an example of the structure of a radar device.

[0025] Figure 6 This is a diagram illustrating an example of the transmitted and reflected wave signals when a chirp pulse is used.

[0026] Figure 7 This is a diagram illustrating an example of Doppler aliasing determination.

[0027] Figure 8 This is a diagram illustrating an example of antenna configuration.

[0028] Figure 9 This is a diagram illustrating an example of antenna configuration.

[0029] Figure 10 This is a diagram illustrating an example of antenna configuration.

[0030] Figure 11 This is a diagram illustrating an example of antenna configuration.

[0031] Figure 12 This is a diagram illustrating an example of antenna configuration.

[0032] Figure 13 This is a diagram illustrating an example of antenna configuration.

[0033] Figure 14 This is a diagram illustrating an example of antenna configuration.

[0034] Figure 15 This is a diagram illustrating the configuration example of the transceiver antenna and virtual receiver array in Configuration Example 1.

[0035] Figure 16 This is a diagram illustrating an example of the computer simulation results of the orientation estimation process in Configuration Example 1.

[0036] Figure 17 This is a diagram illustrating an example of the computer simulation results of the orientation estimation process in Configuration Example 1.

[0037] Figure 18 This is a diagram illustrating the configuration example of the transceiver antenna and virtual receiver array in Configuration Example 1.

[0038] Figure 19 This is a diagram illustrating the configuration example of the transmit and receive antennas in Configuration Example 2.

[0039] Figure 20 This is a diagram illustrating a configuration example of the virtual receiver array in Configuration Example 2.

[0040] Figure 21 This is a diagram illustrating an example of the computer simulation results of the orientation estimation process in Configuration Example 2.

[0041] Figure 22 This is a diagram illustrating the configuration example of the transmit and receive antennas in Configuration Example 2.

[0042] Figure 23 This is a diagram illustrating a configuration example of the virtual receiver array in Configuration Example 2.

[0043] Figure 24 This is a diagram illustrating the configuration example of the transmit and receive antennas in Configuration Example 2.

[0044] Figure 25 This is a diagram illustrating a configuration example of the virtual receiver array in Configuration Example 2.

[0045] Figure 26 This is a diagram illustrating the configuration example of the transmit and receive antennas in Configuration Example 2.

[0046] Figure 27 This is a diagram illustrating a configuration example of the virtual receiver array in Configuration Example 2.

[0047] Figure 28 This is a diagram illustrating the configuration example of the transmit and receive antennas in Configuration Example 2.

[0048] Figure 29 This is a diagram illustrating a configuration example of the virtual receiver array in Configuration Example 2.

[0049] Explanation of reference numerals in the attached figures

[0050] 10. Radar Equipment

[0051] 100 Radar Transmission Unit

[0052] 101 Radar Transmitting Signal Generation Unit

[0053] 102 Modulation signal generation unit

[0054] 103 VCO

[0055] 104 Encoding Generation Department

[0056] 105 Phase Rotation Unit

[0057] 106-1 First transmitting antenna

[0058] 106-2 Second transmitting antenna

[0059] 200 Radar Receiving Unit

[0060] 201 Antenna System Processing Department

[0061] 202 Receiving Antenna

[0062] 203 Wireless Receiver Unit

[0063] 204 Mixer Section

[0064] 205 LPF

[0065] 206 Signal Processing Department

[0066] 207 AD Conversion Section

[0067] 208 Beat Frequency Analysis Department

[0068] 209 Output Switching Unit

[0069] 210 Doppler Analysis Department

[0070] 211 CFAR Department

[0071] 212 Folding Detection Unit

[0072] 213 Encoding Multiplexing Separator

[0073] 214 Direction Estimation Department

[0074] 215 Phase Correction Unit

[0075] 300 Positioning Output Unit Detailed Implementation

[0076] MIMO radar, for example, transmits radar signals (or "radar transmit waves") multiplexed using time division, frequency division, or code division from multiple transmit antennas (or, referred to as "transmit array antennas"). Then, MIMO radar, for example, uses multiple receive antennas (or, referred to as "receive array antennas") to receive signals reflected by surrounding objects (e.g., "radar reflect waves"), and separates and receives the multiplexed transmit signals from the individual received signals. Through this processing, MIMO radar can obtain the propagation path response represented by the product of the number of transmit antennas and the number of receive antennas, and perform array signal processing on these received signals as a virtual receive array.

[0077] In MIMO radar, by carefully planning the configuration of antenna elements in the transmit and receive array antennas, a virtual receive array antenna (hereinafter referred to as "virtual receive array") can be constructed with a maximum size equal to the product of the number of transmit antenna elements and the number of receive antenna elements. This allows for an increase in the effective aperture length of the array antenna with a smaller number of elements, thereby improving angular resolution.

[0078] In addition to performing one-dimensional scanning (angle measurement) in the vertical or horizontal direction, MIMO radar can also be applied when performing two-dimensional beam scanning (angle measurement) in both the vertical and horizontal directions (for example, see Non-Patent Document 2).

[0079] As an example, Figure 1(a) indicates that it is contained in the vertical direction. Figure 1 The transmitting array antennas (Tx#1 to Tx#4) arranged in the longitudinal direction in (a) and included in the horizontal direction ( Figure 1 The receiving array antenna consists of four receiving antennas (Rx#1 to Rx#4) arranged in the horizontal direction in (a). Figure 1 In (a), the transmitting antennas are equally spaced (d) in the vertical direction. V The receiving antennas are configured in a horizontally spaced manner (d) H (e.g., see non-patent literature 2).

[0080] Figure 1 (b) indicates that it contains Figure 1 The antenna configuration shown in (a) is a virtual receiver array of the transceiver array antenna. Figure 1 The virtual receiving array shown in (b) consists of 16 virtual receiving antenna elements (VA#1 to VA#16), arranged in a rectangular shape with four antennas horizontally and four antennas vertically. Figure 1 In (b), the horizontal and vertical element spacings of the virtual receiving array are d and d, respectively. H d V The horizontal and vertical aperture lengths A of the virtual receiver array. H A V 3D respectively H 3D V .

[0081] Figure 2 (a) and Figure 2 (b) indicates that in Figure 1 In the antenna configuration of the MIMO radar shown in (a), the horizontal element spacing d H =0.5λ, vertical component spacing d V Fourier beam patterns in the horizontal and vertical directions when λ = 0.5λ. Furthermore, λ represents the wavelength of the radar carrier wave.

[0082] like Figure 2 (a) and Figure 2 As shown in (b), the main beam (main lobe) is formed in the horizontal and vertical directions of 0°. Here, the narrower the beamwidth of the main beam, the higher the angular separation performance for multiple targets. For example, in... Figure 2 (a) and Figure 2 In (b), the beamwidth for a power value of 3dB is approximately 26°. Additionally, as... Figure 2 (a) and Figure 2As shown in (b), side lobes are generated around the main beam. In radar systems, side lobes are a major cause of false artifact detection. Therefore, the lower the peak level of the side lobes, the lower the probability of the radar system falsely detecting artifacts. Figure 2 (a) and Figure 2 In (b), for example, the power ratio relative to the peak level of the sidelobe (Peak Sidelobe Level Ratio (PSLR)) obtained by normalization based on the peak level of the main beam is approximately -13 dB (however, this is with equal amplitude beam weighting).

[0083] Furthermore, in Patent Document 1, the transmitting antenna's antenna elements (e.g., element groups) arranged at equal intervals in the vertical direction are arranged in at least two columns facing each other at equal intervals in the horizontal direction. The receiving antenna's antenna elements (e.g., element groups) arranged at equal intervals in the horizontal direction are spaced apart by the same amount of spacing as the columns containing the transmitting antenna, and are arranged in at least two columns facing each other at equal intervals in the vertical direction. Based on this antenna configuration, similar to Non-Patent Document 2, a rectangular and planar, closely spaced virtual array configuration can be obtained. Even in this case, for example, the power ratio (PSLR) relative to the peak level of the sidelobes, normalized according to the peak level of the main beam, is approximately -13 dB (however, this is under the condition of using equal-amplitude beam weighting).

[0084] pass Figure 1 The antenna configuration of the MIMO radar shown in (a) is as follows: Figure 1 As shown in (b), the virtual receiving antennas are uniformly arranged in a planar manner. Here, Figure 1 The aperture of the virtual receiving antenna shown in (b) is the same in the vertical direction as the aperture of the transmitting antenna. In other words, the number of elements of the virtual receiving antenna arranged in the vertical direction is the same as the number of elements (e.g., Nt) arranged in the vertical direction of the transmitting antenna. Similarly, Figure 1 The aperture of the virtual receiving antenna shown in (b) is the same as the aperture of the receiving antenna in the horizontal direction. In other words, the number of elements of the virtual receiving antenna configured in the horizontal direction is the same as the number of elements (e.g., Nr) arranged in the horizontal direction of the receiving antenna.

[0085] Therefore, the product of the number of elements arranged vertically (Nt) and the number of elements arranged horizontally (Nr) of the virtual receiving antenna is Nt×Nr, which is equal to the product of the number of transmitting and receiving antennas, Nt×Nr. The aperture of the virtual receiving antenna is set (in other words, limited or restricted) to a value up to Nt×Nr.

[0086] For example, in Patent Document 1, the queues of antenna elements of the transmitting antenna, which are equally spaced vertically, are arranged facing each other in at least two columns in the horizontal direction. Therefore, the horizontal aperture of the virtual receiving antenna is increased to at least twice the number of receiving antenna elements arranged between the queues of transmitting antenna elements. In other words, the number of elements arranged in the horizontal direction of the virtual receiving antenna is at least twice the number of elements in the horizontal direction of the receiving antenna.

[0087] Similarly, for example, in Patent Document 1, the queues of antenna elements of the receiving antenna, which are equally spaced in the horizontal direction, are arranged facing each other in at least two columns in the vertical direction at intervals equal to those of the columns of the transmitting antenna. Therefore, the vertical aperture of the virtual receiving antenna is increased to at least twice the number of transmitting antenna elements arranged between the queues of receiving antenna elements. In other words, the number of elements arranged in the vertical direction of the virtual receiving antenna is at least twice the number of elements in the vertical direction of the transmitting antenna.

[0088] Here, let the number of transmitting antennas (or antenna elements) arranged vertically be "Nta", and let the queues of Nta antennas be arranged in rows facing each other in the horizontal direction as "Ntb". Similarly, let the number of receiving antennas (or antenna elements) arranged horizontally be "Nra", and let the queues of Nra antennas be arranged in rows facing each other in the vertical direction as "Nrb". That is, the number of transmitting antennas is Nt = Nta × Ntb, and the number of receiving antennas is Nr = Nra × Nrb.

[0089] In this case, the number of elements arranged vertically in the virtual receiving antenna is Nrb times the number of elements Nta in the vertical direction of the transmitting antenna (=Nta×Nrb). Furthermore, the number of elements arranged horizontally in the virtual receiving antenna is Ntb times the number of elements Nra in the horizontal direction of the receiving antenna (=Nra×Ntb). Therefore, the product of the number of elements arranged vertically and horizontally in the virtual receiving antenna is Nta×Nrb×Nra×Ntb=Nt×Nr, and the product of the number of transmitting and receiving antennas is Nt×Nr, for example, with… Figure 1 Their antenna configurations are the same.

[0090] As described above, in the antenna configuration disclosed in Patent Document 1, the effect of increasing the number of elements arranged in the vertical direction and the number of elements arranged in the horizontal direction of the virtual receiving antenna is limited. As a result, the increase in the antenna aperture length is also limited, and therefore, the improvement of the angle measurement performance of the radar device is also limited.

[0091] Additionally, for example, in a MIMO array configuration, a radar device might misjudge the angle of arrival of multiple waves with a specific angle of difference in received signal levels. As an example, Figure 3(a) represents an example of a configuration where the transmitting and receiving antennas are in an "L" shape (e.g., referred to as a "transmit-receive L-shaped configuration"). Figure 3 (b) indicates that it contains Figure 3 The antenna configuration shown in (a) is a virtual receiver array of the transceiver array antenna.

[0092] For example, in Figure 3 In the virtual receiving antenna configuration shown in (b), where a virtual antenna is configured in the vertical (or horizontal) direction (e.g., VA#39, VA#40, VA#47 and VA#48 (or VA#9-VA#13, VA#17-VA#21 and VA#25-VA#29)), the radar device may have difficulty separating multiple waves in the horizontal (or vertical) direction.

[0093] Additionally, for example in Figure 3 In the virtual receiving antenna configuration shown in (b), when multiple virtual antennas are arranged in a vertical (or horizontal) position, the radar device can separate multiple waves in the horizontal (or vertical) direction. However, when the spacing between the virtual antennas in the horizontal (or vertical) position is more than one wavelength, the radar device may have difficulty separating multiple waves at a specific horizontal (or vertical) interval (e.g., an azimuth (or elevation) interval that produces grating lobes).

[0094] Figure 4 Indicates in Figure 3 (a) and Figure 3 Fourier beamforms (computer simulation of the estimated results) for two waves with equal received power and angles of arrival (H, V) of (20°, 20°) and (-20°, -20°) respectively, in the antenna configuration of the MIMO radar shown in (b).

[0095] like Figure 4 As shown, false peaks will be generated at a high level (e.g., the same level as the true value) in directions different from the true value directions (20°, 20°) and (-20°, -20°), such as the (20°, -20°) and (-20°, 20°) directions.

[0096] Therefore, in one embodiment of this disclosure, a method is described to improve two-dimensional angle measurement performance by using a MIMO array configuration capable of separating multiple waves. Additionally, in another embodiment of this disclosure, a method is described to improve two-dimensional angle measurement performance by using a MIMO array configuration that expands the aperture of the virtual receiving antenna in both the vertical and horizontal dimensions.

[0097] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. Furthermore, in the embodiment, the same constituent elements are labeled with the same reference numerals, and their descriptions are omitted due to repetition.

[0098] The following describes a radar device with a structure (in other words, a MIMO radar structure) in which different transmitted signals, multiplexed by code division, are sent from multiple transmit antennas via a transmit branch, and the received signals are separated and processed by a receive branch. However, the structure of the radar device is not limited to this; it can also be structured such that different transmitted signals, multiplexed by frequency division, are sent from multiple transmit antennas via a transmit branch, and the received signals are separated and processed by a receive branch. Similarly, the radar device can also be structured such that time-division multiplexed transmitted signals are sent from multiple transmit antennas via a transmit branch, and the received signals are processed by a receive branch.

[0099] Similarly, the radar device can also be structured such that different transmitted signals, multiplexed by Doppler division, are transmitted from multiple transmitting antennas by a transmitting branch, and the receiving branch separates each transmitted signal for reception processing. Likewise, the radar device can also be structured such that transmitted signals, multiplexed by at least two of code division multiplexing, time division multiplexing, and Doppler division multiplexing, are transmitted from multiple transmitting antennas by a transmitting branch, and the receiving branch separates each transmitted signal for reception processing.

[0100] Furthermore, the following description, as an example, illustrates a radar configuration using frequency-modulated pulse waves such as chirped pulses (e.g., also referred to as "fast chirp modulation"). However, the modulation method is not limited to frequency modulation. For example, one embodiment of this disclosure can also be applied to radar configurations using single pulses or coded pulses.

[0101] [Structure of a radar device]

[0102] Figure 5 This is a block diagram illustrating a structural example of the radar device 10 according to this embodiment.

[0103] The radar device 10 includes a radar transmitter (transmitter branch) 100, a radar receiver (receiver branch) 200, and a positioning output unit 300.

[0104] The radar transmitter 100 (e.g., equivalent to a transmitting circuit) generates a radar signal (radar transmission signal) and transmits the radar transmission signal at a predetermined transmission period using a transmitting array antenna composed of multiple transmitting antennas 106.

[0105] The radar receiver 200 (e.g., equivalent to a receiving circuit) uses a receiving array antenna, for example, comprising multiple receiving antennas 202 (e.g., Na), to receive radar transmitted signals, i.e., reflected wave signals, after being reflected by a target (object, not shown). The radar receiver 200 performs signal processing on the reflected wave signals received in each receiving antenna 202, such as detecting the presence or absence of an object, or estimating the distance of arrival, Doppler frequency (in other words, relative velocity), and direction of arrival of the reflected wave signal, and outputs information related to the estimation results (in other words, location information).

[0106] The positioning output unit 300 performs positioning output processing based on information related to the estimation result of the direction of arrival input from the radar receiver 200.

[0107] In addition, the radar device 10 can also be mounted on a mobile body such as a vehicle, and the radar receiver 200 or the positioning output unit 300 can also be connected to an ECU (Electronic Control Unit) (not shown) such as an Advanced Driver Assistance System (ADAS) or an autonomous driving system to improve collision safety, and use the positioning output (information related to the estimation result) for vehicle drive control or alarm control.

[0108] Additionally, the radar device 10 can be installed on high structures such as roadside utility poles or traffic lights (not shown). The radar device 10 can also be used as a sensor in auxiliary systems to improve the safety of passing vehicles or pedestrians, or in systems preventing suspicious intrusion (not shown). The radar receiver 200 or the positioning output unit 300 can be connected to a control device (not shown) that can also be connected to the auxiliary system for improving safety or the system preventing suspicious intrusion, and use the positioning output for alarm control or anomaly detection control. Furthermore, the application of the radar device 10 is not limited to these uses and can be used for other purposes.

[0109] In addition, the target is an object that is detected by the radar device 10, such as vehicles (including four-wheeled and two-wheeled vehicles), people, boulders or curbs.

[0110] [Structure of Radar Transmitter 100]

[0111] The radar transmitter 100 includes a radar transmission signal generation unit 101, a coding generation unit 104, a phase rotation unit 105, and a transmission antenna 106.

[0112] The radar transmission signal generation unit 101 generates, for example, a radar transmission signal (in other words, a baseband signal). The radar transmission signal generation unit 101 includes, for example, a modulation signal generation unit 102 and a VCO (Voltage Controlled Oscillator) 103. Hereinafter, each component of the radar transmission signal generation unit 101 will be described.

[0113] For example, such as Figure 6 As shown in the upper layer, the modulation signal generation unit 102 generates a sawtooth-shaped modulation signal (in other words, a modulation signal for VCO control) according to the radar transmission period Tr.

[0114] VCO103 outputs a frequency modulation signal (hereinafter referred to as "frequency chirp signal" or "chirp signal") to the phase rotation unit 105 based on the radar transmission signal (modulation signal) output from the modulation signal generation unit 102.

[0115] In addition, the chirped signal generated in the radar signal generation unit 101 is output to the radar receiver unit 200 (mixer unit 204 described later).

[0116] The encoding generation unit 104 generates different codes according to the transmitting antenna 106 for coded multiplexing transmission. The encoding generation unit 104 outputs the phase rotation amount corresponding to the generated code to the phase rotation unit 105. In addition, the encoding generation unit 104 outputs information related to the generated code to the radar receiving unit 200 (output switching unit 209 described later).

[0117] The phase rotation unit 105, for example, adds a phase rotation amount input from the encoding generation unit 104 to the chirp signal input from the radar transmit signal generation unit 101, and outputs the phase-rotated signal to the transmit antenna 106 (e.g., the first transmit antenna 106-1 and the second transmit antenna 106-2). For example, the phase rotation unit 105 may include a phase generator or a phase modulator (not shown).

[0118] The output signal of the phase rotation unit 105 is amplified to a predetermined transmission power and radiated into space from each of the transmission antennas 106. In other words, the radar transmission signal is encoded and multiplexed from multiple transmission antennas 106 by adding a phase rotation amount corresponding to the encoding.

[0119] Next, an example of the encoding (e.g., orthogonal code) set in the radar device 10 will be described.

[0120] The encoding generation unit 104 can generate different codes, for example, according to the transmitting antenna 106 that performs encoded multiplexing transmission.

[0121] For example, the number of transmitting antennas 106 is set to "N" below. Tx"N." Here, N Tx ≧2.

[0122] Additionally, the number of code multiplexing is set to "N". CM ".exist Figure 5 In the example, N is used to illustrate CM =N Tx This is one possible scenario, but not a limitation. For example, the same code can also be transmitted in a group of multiple transmit antennas 106 (e.g., array transmission or beamforming transmission). In this case, N CM <N Tx .

[0123] The encoding generation unit 104, for example, takes the N contained in the encoded sequence (e.g., an orthogonal code sequence (or simply called "encoding" or "orthogonal code") of the code length (in other words, the number of encoded elements) Loc. allcode One (or, sometimes also written as "N") allcode (Loc) of N in the orthogonal code CM Each orthogonal code is set as the encoding used for encoding multiplexing and transmission.

[0124] For example, the number of code multiplexing N CM Less than orthogonal code number N allcode N CM <N allcode In other words, the code length Loc of an orthogonal code is greater than the coding multiplexing number N. CM For example, N of the code length Loc CM An orthogonal code is represented as Code. ncm =[OC ncm (1), OC ncm (2), ..., OC ncm (Loc)]. Here, "OC" ncm "(noc)" represents the nth orthogonal key Code. ncm The noc-th encoded element in the code. Additionally, "ncm" represents the index of the orthogonal code used for code multiplexing, ncm = 1, ..., N. CM Additionally, "noc" represents the index of the encoded element, where noc = 1, ..., Loc.

[0125] Here, the code length Loc is N. allcode (N) of the orthogonal keys allcode -N CM The N orthogonal codes will not be used by the encoding generation unit 104 (in other words, they will not be used for encoded multiplexing transmission). Hereinafter, (N) allcode -N CMThe orthogonal codes that are not used by the encoding generation unit 104 are called "unused orthogonal codes". At least one of the unused orthogonal codes is used, for example, for the folding determination of the Doppler frequency in the folding determination unit 212 of the radar receiver 200, which will be described later (an example will be described later).

[0126] By using non-orthogonal codes, the radar device 10 is able to separately receive individual signals transmitted by multiple transmitting antennas 106 under conditions of suppressed inter-symbol interference, and is able to expand the range of detectable Doppler frequencies (an example will be described later).

[0127] As described above, N generated in the encoding generation unit 104 CM An orthogonal code is, for example, a code that is orthogonal to itself (in other words, uncorrelated codes). For example, Walsh-Hadamard codes can be used in orthogonal code sequences. The code length of a Walsh-Hadamard code is a power of 2, and each code length contains the same number of orthogonal codes as its code length. For example, Walsh-Hadamard codes with code lengths of 2, 4, 8, or 16 contain 2, 4, 8, or 16 orthogonal codes, respectively.

[0128] As an example, the number of codes can be set to N in a manner that satisfies the following equation (1). CM The code length Loc of an orthogonal code sequence.

[0129]

[0130] Here, ceil[x] is the operator (top function) that outputs the smallest integer greater than or equal to the real number x. In the case of a Walsh-Hadamard code with a code length of Loc, N holds true. allcode The relationship (Loc) = Loc. For example, Walsh-Hadamard codes with code lengths Loc = 2, 4, 8, or 16 contain 2, 4, 8, or 16 orthogonal codes respectively. Therefore, N holds true. allcode (2) = 2, N allcode (4) = 4, N allcode (8) = 8 and N allcode (16) = 16. The encoding generation unit 104 can, for example, use the N contained in a Walsh-Hadamard code with a code length of Loc. allcode N out of (Loc) codes CM An orthogonal code.

[0131] Here, the code length is explained. For example, when the moving speed of the target or radar device 10 includes acceleration, a longer code length makes it more susceptible to inter-symbol interference. Furthermore, a longer code length results in a larger candidate Doppler folding range for Doppler folding determination, as described later. Therefore, when multiple Doppler frequencies exist within different folding ranges of the same range index, the probability of repeated Doppler frequency indices detected within different folding ranges increases, thus increasing the probability that the radar device 10 will have difficulty properly determining folding.

[0132] Therefore, from the viewpoint of performance and computational complexity of the fold determination in the fold determination unit 212 of the radar receiver 200 (described later), the radar device 10 can also use a code with a shorter code length. As an example, the radar device 10 can also use the orthogonal code sequence with the shortest code length in the code length Loc that satisfies equation (1).

[0133] Furthermore, Walsh-Hadamard codes with code length Loc, for example, include codes with code length Loc [OC]. ncm (1), OC ncm (2), ..., OC ncm (Loc-1), OC ncm In the case of (Loc)], the Walsh-Hadamard code of code length Loc also contains the encoding [OC]. ncm (1), -OC ncm (2), ..., OC ncm (Loc-1), -OC ncm [(Loc)], the odd-numbered coded elements are the same, while the sign of the even-numbered coded elements is reversed.

[0134] Furthermore, even other codes that differ from Walsh-Hadamard codes with a code length of Loc, such as those in codes containing a code length of Loc [OC], are not considered. ncm (1), OC ncm (2), ..., OC ncm (Loc-1), OC ncm In the case of (Loc)], the encoding of code length Loc can be the encoding [OC] ncm (1), -OC ncm (2), ..., OC ncm (Loc-1), -OC ncm [(Loc)], where the odd-numbered coded elements are the same, while the sign of the even-numbered coded elements is reversed; or, it can be the encoding [-OC] ncm (1), OC ncm (2), ..., -OC ncm (Loc-1), OC ncm[(Loc)], the even-numbered coded elements are the same, while the sign of the odd-numbered coded elements is reversed.

[0135] The number of unused orthogonal keys (N) allcode -N CM When the value is 2 or higher, the radar device 10 may, for example, select a group of codes that do not contain the aforementioned relationship in the unused orthogonal codes. For example, in the group of codes containing the aforementioned relationship, one code may be used for code multiplexing transmission, while another code may be included in the unused orthogonal codes. By selecting the unused orthogonal codes, the folding determination accuracy of the Doppler frequency in the folding determination unit 212 of the radar receiver 200, which will be described later, can be improved (an example will be described later).

[0136] Next, the number of multiplexing codes N will be explained. CM An example of an orthogonal code.

[0137] <N CM =2 or 3 cases>

[0138] In N CM In the case of 2 or 3, for example, Walsh-Hadamard codes with code lengths Loc = 4, 8, 16, 32, ... can be applied. In these cases of code length Loc, N CM <N allcode (Loc). Additionally, please note the following case: when the number of encoding multiplexing is N. CM In the case of =2 or 3, use the shortest Walsh-Hadamard code in the Loc (e.g., Loc = 4).

[0139] For example, the Walsh-Hadamard code for code length Loc is denoted as "WH". Loc (nwhc)”. In addition, nwhc represents the coding index contained in the Walsh-Hadamard code of code length Loc, nwhc = 1, ..., Loc. For example, the Walsh-Hadamard code of code length Loc = 4 contains the orthogonal codes WH4(1) = [1,1,1,1], WH4(2) = [1,-1,1,-1], WH4(3) = [1,1,-1,-1] and WH4(4) = [1,-1,-1,1].

[0140] Here, WH4(1) = [1, 1, 1, 1] and WH4(2) = [1, -1, 1, -1] in Walsh-Hadamard codes with Loc = 4 are groups of codes whose odd-numbered coded elements are the same, while the signs of their even-numbered coded elements are reversed. Additionally, WH4(3) = [1, 1, -1, -1] and WH4(4) = [1, -1, -1, 1] are also groups of codes whose relationships with each other are the same as those of WH4(1) and WH4(2).

[0141] For example, in the number of unused orthogonal keys (N) allcode -N CM When the value is 2 or higher, the radar device 10 can also select a group of codes that do not contain this relationship in the unused orthogonal codes.

[0142] For example, in the number of encoding multiplexing N CM When the length of the code is 2, the encoding generation unit 104 determines two orthogonal codes from the Walsh-Hadamard code with a code length of Loc = 4 as the codes for code multiplexing transmission. In this case, the number of unused orthogonal codes (N) allcode -N CM There are 2.

[0143] For example, the encoding generation unit 104 may select the encoding for multiplexing transmission in a group of encodings that do not include WH4(1) and WH4(2) in the unused orthogonal codes, or in a group of encodings that include WH4(3) and WH4(4). For example, the combination of encodings (Code1 and Code2) for multiplexing transmission may be a combination of Code1 = WH4(1) (=[1,1,1,1]) and Code2 = WH4(3) (=[1,1,-1,-1]), a combination of Code1 = WH4(1) and Code2 = WH4(4), a combination of Code1 = WH4(2) and Code2 = WH4(3), or a combination of Code1 = WH4(2) and Code2 = WH4(4).

[0144] In addition, in the number of encoding multiplexing N CM In the case where the code length Loc = 2, for example, the folding determination unit 212 in the radar receiver 200 can determine the code length Loc = 4 for N. allcode = 2 out of 4 Walsh-Hadamard codes that were not used by the encoding generation unit 104 (in other words, not used for encoding multiplexing transmission) (= N) allcode -N CM At least one of the orthogonal codes was not used for folding determination (an example will be described later).

[0145] Below, the N of the code length Loc will be... allcode Unused orthogonal codes among a set of orthogonal codes are denoted as "UnCode". nuc =[UOC nuc (1), UOC nuc (2), ..., UOC nuc (Loc)]”. In addition, UnCode nuc This indicates the nuc-th unused orthogonal key. Additionally, nuc represents the index of the unused orthogonal key, where nuc = 1, ..., (N). allcode -N CMAdditionally, UOC nuc (noc) represents the nuc-th unused orthogonal code UnCode. nuc The noc-th encoded element. Additionally, noc represents the index of the encoded element, noc = 1, ..., Loc.

[0146] For example, when the number of encoding multiplexing is N CM =2, and the encoding for transmission multiplexing determined by the encoding generation unit 104 is Code1 = WH4(1) (=[1,1,1,1]) and Code2 = WH4(3) (=[1,1,-1,-1]), and the orthogonal codes not used are UnCode1 = WH4(2) (=[1,-1,1,-1]) and UnCode2 = WH4(4) (=[1,-1,-1,1]). In addition, the combination of not using orthogonal codes (UnCode1 and UnCode2) is not limited to the combination of WH4(2) and WH4(4), but can also be other combinations of encodings.

[0147] Similarly, in the encoding multiplexing number N CM When the length of the code is 3, the encoding generation unit 104, for example, determines the three orthogonal codes in the Walsh-Hadamard code with a code length of Loc = 4 as the codes for code multiplexing transmission. In this case, the number of unused orthogonal codes (N) allcode -N CM ) is 1.

[0148] For example, the encoding generation unit 104 may also select Code1 = WH4(3) = [1,1,-1,-1], Code2 = WH4(4) = [1,-1,-1,1] and Code3 = WH4(2) = [1,-1,1,-1].

[0149] Additionally, the folding determination unit 212 of the radar receiver 200 can determine the N code length Loc = 4. allcode = 1 of 4 Walsh-Hadamard codes (= N) allcode -N CM Orthogonal codes were not used for folding determination (an example will be described later). For example, in a coding multiplexing number of N... CM=3, and the codes for multiplexing transmission determined by the encoding generation unit 104 are Code1 = WH4(3) = [1,1,-1,-1], Code2 = WH4(4) = [1,-1,-1,1], and Code3 = WH4(2) = [1,-1,1,-1], then the unused orthogonal code is UnCode1 = WH4(1) = [1,1,1,1]. Furthermore, the combination of the codes for multiplexing transmission (Code1, Code2, and Code3) with the unused orthogonal code (UnCode1) is not limited to these combinations, and can also be other combinations of codes.

[0150] Furthermore, even in the coding multiplexing number N CM When the value is 5 or higher, the radar device 10 can also be used with the coding multiplexing number N. CM The cases of 2 to 4 similarly determine the encoding used for multiplexing and transmission, and whether orthogonal codes are used.

[0151] For example, the encoding generation unit 104 may also select N in the Walsh-Hadamard code of code length Loc shown in equation (2). CM N orthogonal codes are used as codes for code multiplexing and transmission. In this case, N CM <Loc=N allcode .

[0152]

[0153] Additionally, the folding determination unit 212 in the radar receiver 200 can determine the N of the code length Loc. allcode = Loc Walsh-Hadamard codes (N) allcode -N CM ) unused orthogonal keys are used for folding determination (an example will be described later). Additionally, the number of unused orthogonal keys (N) allcode -N CM When there are two or more codes, the encoding generation unit 104 may select the code for transmission by encoding multiplexing in the following manner, that is, making any one of the odd-numbered and even-numbered coding elements in the Walsh-Hadamard code of code length Loc the same, while the group of codes whose signs are reversed for the other coding element in the odd-numbered and even-numbered coding elements is not included in the unused orthogonal code.

[0154] In other words, the encoding generation unit 104 may select the encoding for multiplexing transmission in the following manner, for example, such that the encodings in the Walsh-Hadamard code of code length Loc are identical to each other in either the odd-numbered or even-numbered encoding elements, while the encodings of the other encoding element in the odd-numbered or even-numbered encoding elements are either included in the unused orthogonal code, and the other encoding is not included in the unused orthogonal code.

[0155] Furthermore, the elements constituting an orthogonal code sequence are not limited to real numbers, but may also include complex values.

[0156] Alternatively, the encoding can be other orthogonal codes different from Walsh-Hadamard codes. For example, the encoding can also be an orthogonal M-sequence code or a pseudo-orthogonal code.

[0157] The above explains the multiplexing number N for each code. CM An example of an orthogonal code.

[0158] Next, an example of the phase rotation amount of the code for multiplexing transmission generated in the encoding generation unit 104 will be described.

[0159] Radar device 10, for example, for transmit antennas Tx#1 to Tx#N that perform coded multiplexing transmission. TX The encoding multiplexing transmission uses different orthogonal codes for each transmission. Therefore, the encoding generation unit 104, for example, in the m-th transmission period Tr, sets the orthogonal code-based Code assigned to the n-th transmission antenna Tx#ncm. ncm Phase rotation ψ ncm (m), and output to the phase rotation unit 105. Here, ncm = 1, ..., N CM .

[0160] For example, as a phase rotation quantity ψ ncm (m), during the transmission period of code length Loc times, is cyclically assigned the orthogonal code Code as shown in equation (3). ncm Loc encoded elements OC ncm (1), ..., OC ncm (Loc) represents the corresponding phase quantity.

[0161] ψ ncm (m)=angle[OC ncm (OC_INDEX)] (3)

[0162] Here, `angle(x)` is the operator that outputs the radian phase of the real number `x`, where `angle(1) = 0`, `angle(-1) = π`, `angle(j) = π / 2`, and `angle(-j) = -π / 2`. `j` is the imaginary unit. Additionally, `OC_INDEX` indicates the orthogonal code sequence `Code`. ncm The orthogonal code element index of the element can be changed cyclically in the range of 1 to Loc according to the transmission period (Tr), as shown in equation (4).

[0163] OC_INDEX = mod(m-1, Loc) + 1 (4)

[0164] Here, mod(x, y) is the modulus operator and a function that outputs the remainder after dividing x by y. Additionally, m = 1, ..., Nc. Nc is the predetermined number of transmission cycles (hereinafter referred to as "radar signal transmission count") used by the radar device 10 for radar positioning. Furthermore, the radar device 10 transmits radar signals a number Nc that is, for example, an integer multiple of Loc (e.g., Ncode times). For example, Nc = Loc × Ncode.

[0165] In addition, the encoding generation unit 104 outputs the orthogonal code element index OC_INDEX to the output switching unit 209 of the radar receiving unit 200 according to the transmission cycle (Tr).

[0166] Phase rotation unit 105 includes, for example, a component with N Tx Each transmitting antenna 106 corresponds to a phaser or phase modulator. The phase rotation unit 105, for example, assigns a phase rotation amount ψ, input from the encoding generation unit 104, to the chirp signal input from the radar transmitting signal generation unit 101 according to the transmission period Tr. ncm (m).

[0167] For example, the phase rotation unit 105 assigns an orthogonal code Code based on the code assigned to the nth transmitting antenna Tx#ncm to the chirp signal input from the radar transmitting signal generation unit 101 according to the transmission period Tr. ncm Phase rotation ψ ncm (m). Here, ncm = 1, ..., N CM , m=1、…、Nc.

[0168] For N Tx The output from the phase rotation unit 105 of each transmitting antenna 106, after being amplified to a specified transmission power, is from N Tx A transmitting antenna 106 (e.g., a transmitting array antenna) radiates into space.

[0169] As an example, this illustrates the number N of transmitting antennas 106.Tx =3. Encoding multiplexing number N CM The case of 3-bit encoding multiplexing transmission. Furthermore, the number of transmit antennas N. Tx and the number of code reuses N CM It is not limited to these values.

[0170] For example, in the m-th transmission cycle Tr, the phase rotation amounts ψ1(m), ψ2(m) and ψ3(m) are output from the encoding generation unit 104 to the phase rotation unit 105.

[0171] The first (ncm=1) portion of the phase rotation unit 105 (in other words, the phaser corresponding to the transmitting antenna 106 (e.g., Tx#1)) applies a phase rotation amount as shown in equation (5) to the chirp signal generated in the radar transmitting signal generation unit 101 according to the transmitting period Tr. The output of the first portion of the phase rotation unit 105 is transmitted by the transmitting antenna 106 (Tx#1). Here, cp(t) represents the chirp signal output from the radar transmitting signal generation unit 101 for each transmitting period Tr.

[0172] exp[jψ1(1)]cp(t),exp[jψ1(2)]cp(t),exp[jψ1(3)]cp(t),...,exp[jψ1(Nc)]cp(t) (5)

[0173] Similarly, the second (ncm=2) part of the phase rotation unit 105 applies a phase rotation amount as shown in equation (6) to the chirp signal generated in the radar transmission signal generation unit 101 according to the transmission period Tr. The output of the second part of the phase rotation unit 105 is transmitted by the transmission antenna 106 (e.g., Tx#2).

[0174] exp[jψ2(1)]cp(t),exp[jψ2(2)]cp(t),exp[jψ2(3)]cp(t),...,exp[jψ2(Nc)]cp(t) (6)

[0175] Similarly, the third (ncm=3) part of the phase rotation unit 105 applies a phase rotation amount as shown in equation (7) to the chirp signal generated in the radar transmission signal generation unit 101 according to the transmission period Tr. The output of the third part of the phase rotation unit 105 is transmitted by the transmission antenna 106 (e.g., Tx#3).

[0176] exp[jψ3(1)]cp(t),exp[jψ3(2)]cp(t),exp[jψ3(3)]cp(t),...,exp[jψ3(Nc)]cp(t) (7)

[0177] Furthermore, when the radar device 10 is continuously performing radar positioning, it can also variably set the code used as an orthogonal code Code each time radar positioning is performed (e.g., according to a transmission cycle of Nc times (Nc×Tr)). ncm The encoding.

[0178] Additionally, the radar device 10 can also be variably set to N. Tx Each transmitting antenna 106 transmits the output of the phase rotation unit 105 (in other words, the transmitting antenna 106 corresponding to each output of the phase rotation unit 105). For example, the correspondence between the multiple transmitting antennas 106 and the coded sequence for coded multiplexing transmission can also be different each time the radar device 10 performs radar positioning. For example, when the radar device 10 receives signals affected by interference from other radars that differs according to the transmitting antenna 106, the coded multiplexed signal output from the transmitting antenna 106 changes each time radar positioning is performed, thereby achieving the effect of randomizing the interference effect.

[0179] The above describes a structural example of the radar transmitter 100.

[0180] [Structure of Radar Receiver 200]

[0181] exist Figure 5 In this radar receiver 200, there are Na receiving antennas 202 (for example, also referred to as "Rx#1 to Rx#Na"), which constitute an array antenna. In addition, the radar receiver 200 includes Na antenna system processing units 201-1 to antenna system processing units 201-Na, a CFAR (Constant False Alarm Rate) unit 211, a folding determination unit 212, a coding multiplexing separation unit 213, and a direction estimation unit 214.

[0182] Each receiving antenna 202 receives the radar transmitted signal, i.e. the reflected wave signal, after being reflected by a reflective object containing the radar measurement target, and outputs the received reflected wave signal as the received signal to the corresponding antenna system processing unit 201.

[0183] Each antenna system processing unit 201 includes a wireless receiving unit 203 and a signal processing unit 206.

[0184] The wireless receiver 203 includes a mixer 204 and an LPF (low-pass filter) 205. The mixer 204, for example, mixes the received reflected wave signal with a radar transmitted signal, i.e., a chirp signal, input from the radar transmitted signal generation unit 101. The LPF 205 performs LPF processing on the output signal of the mixer 204, thereby outputting a beat signal whose frequency corresponds to the delay time of the reflected wave signal. For example, as... Figure 2 As shown, the difference frequency between the frequency of the transmitted chirped signal (transmitted frequency modulated wave) and the frequency of the received chirped signal (received frequency modulated wave) is obtained as the beat frequency (in other words, the beat signal).

[0185] The signal processing unit 206 of each antenna system processing unit 201-z (where z = any one of 1 to Na) includes an AD (Analog Digital) conversion unit 207, a beat frequency analysis unit 208, an output switching unit 209, and a Doppler analysis unit 210.

[0186] In the signal processing unit 206, the AD conversion unit 207 converts, for example, the signal output from the LPF 205 (e.g., a beat signal) into discrete sampled data that has undergone discrete sampling.

[0187] Beat frequency analysis unit 208, for example, analyzes N obtained within a specified time range (distance gate) according to the transmission period Tr. data Each discrete sampled data point is processed using an FFT (Fast Fourier Transform). The signal processing unit 206 then outputs the spectrum of the peak beat frequency corresponding to the delay time of the reflected wave signal (radar reflected wave). Furthermore, as part of the FFT processing, the beat frequency analysis unit 208 may multiply the data by a window function such as a Hanning window or a Hamming window. By using a window function, the radar device 10 can suppress sidelobes generated around the peak beat frequency.

[0188] Additionally, in N data When the number of discrete sampled data is not a power of 2, the beat frequency analysis unit 208 may, for example, perform FFT processing using data including zero-padding as a power of 2 FFT size.

[0189] Furthermore, for example, when the mixer section 204 is a quadrature mixer structure, the I signal component (in-phase component) and Q signal component (quadrature component) are obtained as the output of the mixer section 204. In this case, for example, an LPF can be applied to each I signal component or each Q signal component output by the mixer section 204, and an AD conversion can be applied to the output, thereby obtaining the AD conversion output of the I signal component and the AD conversion output of the Q signal component. When the mixer section 204 is a quadrature mixer structure, for example, by using the cut-off frequency f of the LPF 205... LPF Set to 2f mb Left and right, the beat frequency analysis unit 208 can analyze f mb up to 2f mb The beat frequency detection within the range of folding is a negative beat frequency, thereby expanding the distance detection range. Furthermore, f mb This represents the maximum beat frequency that can be detected without folding based on the sampling theorem during the FFT processing of the beat frequency analysis unit 208, for example, it can be determined by f mb =N data / (2T RG )=f sa / 2 represents. Here, T RG f represents the time range from the gate. sa This indicates the AD sampling frequency.

[0190] Here, the beat frequency response obtained by transmitting the m-th chirp pulse and output from the beat frequency analysis unit 208 in the z-th signal processing unit 206 is determined by RFT. z (f b , m) represents. Here, f b This represents the beat frequency index, which corresponds to the index (binary number) of the FFT. For example, f b =0, ..., N data / 2-1, z=1,...,Na,m=1,...,N C Beat frequency index f b The smaller the value, the smaller the delay time of the reflected wave signal (in other words, the closer the distance to the target).

[0191] Additionally, the beat frequency index f b Distance information can be converted using the following formula (8). The beat frequency index f will also be used below. b Called "distance index f" b ".

[0192]

[0193] Here, Bw C0 represents the frequency modulation bandwidth of the chirped signal within the distance gate, and C0 represents the speed of light.

[0194] Furthermore, when the mixer section 204 is a quadrature mixer structure, for example, the frequency detected as a negative beat frequency (e.g., f) can be... b =N data The signal of / 2, ..., -1) is considered as the positive beat frequency (f b =N data / 2、…、N data -1) folding. Therefore, for example, it can be expressed as f b =0, ..., N data -1.

[0195] The output switching unit 209 selectively switches the output of the beat frequency analysis unit 208 for each transmission cycle to the OC_INDEX-th Doppler analysis unit 210 out of the Loc Doppler analysis units 210, based on the orthogonal code element index OC_INDEX output from the encoding generation unit 104. In other words, the output switching unit 209 selects the OC_INDEX-th Doppler analysis unit 210 in the m-th transmission cycle Tr.

[0196] The signal processing unit 206, for example, has Loc Doppler analysis units 210-1 to 210-Loc. For example, the output switching unit 209 inputs data to the noc-th Doppler analysis unit 210 in transmission cycles of Loc times (Loc×Tr). Therefore, the noc-th Doppler analysis unit 210 uses data from the Ncode-th transmission cycle of the Nc-th transmission cycle (e.g., the beat frequency response RFT output from the beat frequency analysis unit 208). z (f b ,m)), by distance index f b Perform Doppler analysis. Here, noc is the index of the encoded element, noc = 1, ..., Loc.

[0197] For example, when Ncode is a power of 2, FFT processing can also be applied in Doppler analysis. In this case, the FFT size is Ncode, and the maximum Doppler frequency that will not produce folding, derived from the sampling theorem, is ±1 / (2Loc×Tr). Additionally, the Doppler frequency index f... s The Doppler frequency interval is 1 / (Ncode×Loc×Tr), and the Doppler frequency index is f. s The range is f s =-Ncode / 2,…,0,…,Ncode / 2-1.

[0198] For example, the output VFT of the Doppler analysis unit 210 of the z-th signal processing unit 206.z noc (f b f s ) is represented by the following equation (9). In addition, j is the imaginary unit, and z = 1 to Na.

[0199]

[0200] Furthermore, when Ncode is not a power of 2, for example, FFT processing can be performed by including zero-padded data to a power of 2 data size (FFT size). For example, the FFT size in the Doppler analysis unit 210 with zero-padded data can be set to N. codewzero In the case of the z-th signal processing unit 206, the output VFT of the Doppler analysis unit 210 is... znoc (f b f s ) is represented by the following formula (10).

[0201]

[0202] Here, noc is the index of the encoded element, where noc = 1, ..., Loc. Additionally, the FFT size is N. codewzero The maximum Doppler frequency that will not fold, derived from the sampling theorem, is ±1 / (2Loc×Tr). Additionally, the Doppler frequency index f... s The Doppler frequency interval is 1 / (N) codewzero ×Loc×Tr), Doppler frequency index f s The range is f s =-N codewzero / 2、…、0、…、N codewzero / 2-1.

[0203] The following example illustrates the case where Ncode is a power of 2. Furthermore, in the case where zero padding is used in the Doppler analysis unit 210, the following explanation will use Ncode instead of N... codewzero It can be applied in the same way and achieve the same effect.

[0204] Additionally, the Doppler analysis unit 210 can also be multiplied by a window function, such as a Hanning or Hamming window, during FFT processing. By applying the window function, the radar device 10 can suppress sidelobes generated around the beat frequency peak.

[0205] The above describes the processing in each component of the signal processing unit 206.

[0206] exist Figure 5In this process, the CFAR unit 211 uses the outputs of the Loc Doppler analysis units 210 of each of the first to Nath signal processing units 206 to perform CFAR processing (in other words, to perform adaptive threshold determination) and extracts the distance index f of the peak signal. b_cfar and Doppler frequency index f s_cfar .

[0207] The CFAR unit 211, for example, uses the following formula (11) to process the VFT output of the Doppler analysis unit 210 of the first to Nath signal processing units 206. z noc (f b f s The power of the two components is added together, and a two-dimensional CFAR process including the distance axis and the Doppler frequency axis (equivalent to relative velocity) is performed, or a CFAR process combining one-dimensional CFAR processing is performed. For example, the process disclosed in Non-Patent Document 3 can be applied to the two-dimensional CFAR process or the CFAR process combining one-dimensional CFAR processing.

[0208]

[0209] CFAR unit 211 adaptively sets a threshold and indexes the distances where the received power is greater than the threshold as f. b_cfar Doppler frequency index f s_cfar and received power information PowerFT(f b_cfar f s_cfar The output is sent to the folding determination unit 212.

[0210] Next, the explanation Figure 5 Example of operation of the folding determination unit 212 shown.

[0211] The folding determination unit 212 is based, for example, on the distance index f extracted in the CFAR unit 211. b_cfar and Doppler frequency index f s_cfar The output of the Doppler analysis unit 210 is the Doppler component VFT. z noc (f b_cfar f s_cfar Folding is determined. Here, z = 1, ..., Na, noc = 1, ..., Loc.

[0212] The folding determination unit 212 can, for example, set the Doppler range of the envisioned target to ±1 / (2×Tr) and perform Doppler folding determination processing.

[0213] Here, for example, when Ncode is a power of 2, the Doppler analysis unit 210 applies FFT processing to each encoded element. Therefore, FFT processing is performed using the output from the beat frequency analysis unit 208 with a period of (Loc×Tr). Thus, the Doppler range of the Doppler analysis unit 210 without folding according to the sampling theorem is ±1 / (2Loc×Tr).

[0214] Therefore, the Doppler range of the target envisioned by the fold determination unit 212 is greater than the Doppler range of the Doppler analysis unit 210 that will not produce folds. For example, the fold determination unit 212 envisions performing fold determination processing up to a Doppler range ±1 / (2×Tr) that is Loc times the Doppler range of the Doppler analysis unit 210 that will not produce folds.

[0215] The following describes an example of the fold determination process in the fold determination unit 212.

[0216] Here, as an example, we illustrate the following situation: the number of code reuses N CM =3, and the encoding generation unit 104 uses three orthogonal codes in the Walsh-Hadamard code with code length Loc=4: Code1=WH4(3)=[1,1,-1,-1], Code2=WH4(4)=[1,-1,-1,1] and Code3=WH4(2)=[1,-1,1,-1].

[0217] Folding determination unit 212, for example, N with code length Loc = 4 allcode = 1 of 4 Walsh-Hadamard codes (= N) allcode -N CM Orthogonal codes were not used for folding determination. For example, in a coding multiplexing number of N... CM =3, and the encoding for transmission multiplexing determined by the encoding generation unit 104 is Code1 = WH4(3) = [1,1,-1,-1], Code2 = WH4(4) = [1,-1,-1,1] and Code3 = WH4(2) = [1,-1,1,-1], then the orthogonal code is UnCode1 = WH4(1) = [1,1,1,1].

[0218] For example, when the radar device 10 uses an orthogonal code with a code length of Loc = 4 for encoded multiplexing transmission, as described above, the Doppler analysis unit 210 applies FFT processing to each encoded element. Therefore, FFT processing is performed using the output from the beat frequency analysis unit 208 with a period of (Loc × Tr) = (4 × Tr). As a result, the Doppler range of the Doppler analysis unit 210 that does not produce folding according to the sampling theorem is ±1 / (2Loc × Tr) = ±1 / (8 × Tr).

[0219] For example, compared to the range of Doppler analysis (Doppler range) in the Doppler analysis unit 210, the folding determination unit 212 can perform folding determination within a range that is a multiple of the code length Loc of the orthogonal code sequence. For example, the folding determination unit 212 assumes that the Doppler range in the Doppler analysis unit 210 that does not produce folding is ±1 / (8×Tr) and performs folding determination processing within a range that is 4 times (=Loc) of the Doppler range, =±1 / (2×Tr).

[0220] Here, the distance index f extracted in CFAR section 211 is... b_cfar and Doppler frequency index f s_cfar The corresponding output of the Doppler analysis unit 210 is the Doppler component VFT. z noc (f b_cfar f s_cfar For example, it is possible that within the Doppler range of ±1 / (2×Tr), it includes, for example, Figure 7 (a) and Figure 7 (b) shows the Doppler components that include folding.

[0221] For example, such as Figure 7 As shown in (a), the Doppler component VFT z noc (f b_cfar f s_cfar ) in f s_cfar When <0, within the Doppler range of ±1 / (2×Tr), it is possible that f s_cfar -Ncode、f s_cfar f s_cfar +Ncode and f s_cfar +2Ncode are the 4 (=Loc) Doppler components.

[0222] Additionally, for example, such as Figure 7 As shown in (b), the Doppler component VFT z noc (f b_cfar f s_cfar ) in f s_cfar When the value is greater than 0, within the Doppler range of ±1 / (2×Tr), it is possible that f... s_cfar -2Ncode, f s_cfar -Ncode、f s_cfar and f s_cfar +Ncode, these 4 (=Loc) Doppler components.

[0223] The folding determination unit 212, for example, uses orthogonal codes that are not used, in situations such as... Figure 7Encoding separation processing is performed within the ±1 / (2×Tr) Doppler range shown. For example, the folding decision unit 212 can also perform encoding separation processing for cases where orthogonal codes are not used, such as... Figure 7 The phase changes of the four (=Loc) Doppler components, which include folding, are corrected.

[0224] Next, the fold determination unit 212 determines, for example, whether each Doppler component contains a fold based on the received power of the Doppler components that have been separated by coding without the use of orthogonal codes. For example, the fold determination unit 212 can detect the Doppler component with the lowest received power among the Doppler components containing folds and determine the detected Doppler component as a true Doppler component. In other words, the fold determination unit 212 can determine Doppler components with received power different from the lowest received power among the Doppler components containing folds as pseudo-Doppler components.

[0225] By performing this fold determination process, the fold determination unit 212 can reduce the ambiguity of the Doppler range that includes folds. In addition, by performing this fold determination process, the fold determination unit 212 can expand the range of Doppler frequencies that can be detected without ambiguity to a range of -1 / (2Tr) or more and less than 1 / (2Tr) compared with the Doppler range of the Doppler analysis unit 210 (for example, a range of -1 / (8Tr) or more and less than 1 / (8Tr)).

[0226] Since the encoding separation is performed without using orthogonal codes, for example, for true Doppler components, the phase change of the Doppler component is correctly corrected, and the orthogonality between the orthogonal codes used for coded multiplexing transmission and the unused orthogonal codes is maintained. Therefore, the unused orthogonal codes are uncorrelated with the coded multiplexing transmission signal, and the folding determination unit 212 detects the received power based on the noise level.

[0227] On the other hand, for example, with respect to pseudo-Doppler components, the phase change of these Doppler components is incorrectly corrected, and the orthogonality between the orthogonal codes used for coded multiplexing transmission and the unused orthogonal codes cannot be maintained. As a result, a correlation component (interference component) is generated between the unused orthogonal codes and the coded multiplexing transmission signal. Therefore, for example, the folding determination unit 212 detects a received power greater than the noise level.

[0228] Therefore, as described above, the folding determination unit 212 can determine the Doppler component with the lowest received power among the Doppler components that have been encoded and separated based on the absence of orthogonal codes as a true Doppler component, and determine other Doppler components whose received power is different from the lowest received power as pseudo Doppler components.

[0229] For example, the folding determination unit 212 corrects the phase change of the Doppler component containing the folding based on the output of the Doppler analysis unit 210 in each antenna system processing unit 201, and calculates the value of the UnCode (unused orthogonal code) according to the following formula (12). nuc Received power after encoding separation DeMulUnCode nuc (f b_cfar f s_cfar ,DR).

[0230]

[0231] The folding determination unit 212 uses equation (12) to calculate the output of the Doppler analysis unit 210 in all antenna system processing units 201 using the unused orthogonal code UnCode. nuc The sum of the received power after coding separation. Therefore, the folding determination unit 212 can improve the folding determination accuracy even when the received signal level is low. However, alternatively, instead of equation (12), the folding determination unit 212 can calculate the received power after coding separation using the non-orthogonal code from the output of the Doppler analysis unit 210 in a portion of the antenna system processing unit 201. Even in this case, the folding determination unit 212 can, for example, maintain the folding determination accuracy within a range where the received signal level is sufficiently high and reduce the amount of computation.

[0232] Furthermore, in equation (12), nuc = 1, ..., N allcode -N CM Additionally, DR is an index representing the range of Doppler folds. For example, it can be an integer value within the range of DR = ceil[-Loc / 2], ceil[-Loc / 2]+1, ..., 0, ..., ceil[Loc / 2]-1.

[0233] Additionally, in equation (12), the operator This represents the product of each element of vectors with the same number of elements. For example, relative to an nth-order vector A = [a1, ..., a2]... n ] and B = [b1, ..., b n The product of each element is represented by the following equation (13).

[0234]

[0235] Additionally, in equation (12), the operator "·" represents the vector inner product operator. Furthermore, in equation (12), the superscript T represents the vector transpose, and the superscript * (asterisk) represents the complex conjugate operator.

[0236] In equation (12), α(f s_cfarα(f) represents the "Doppler phase correction vector". s_cfar For example, the Doppler frequency index f extracted in CFAR section 211 s_cfar When the output range of the Doppler analysis unit 210 is set to not include Doppler folding (in other words, the Doppler range), the folding determination unit 212 corrects the Doppler phase rotation caused by the time difference of Doppler analysis between Loc Doppler analysis units 210.

[0237] For example, the Doppler phase correction vector α(f) s_cfar The Doppler phase correction vector α(f) is expressed as shown in equation (14). Equation (14) represents the Doppler phase correction vector α(f). s_cfar For example, a vector with Doppler phase correction coefficients as elements, which are used to correct the output VFT of the first Doppler analysis unit 210. z 1 (f b_cfar f s_cfar Based on the Doppler analysis time, the VFT output from the second Doppler analysis unit 210 is used as a reference. z 2 (f b_cfar f s_cfar The output VFT of the Loc Doppler analysis unit 210 z Loc (f b_cfar f s_cfar The Doppler frequency index f generated by the time delay of Tr, 2Tr, ..., (Loc-1)Tr in each output of ) s_cfar The phase rotation in the Doppler component.

[0238]

[0239] Additionally, in equation (12), β(DR) represents the "folded phase correction vector". Considering the case of Doppler folding, the folded phase correction vector β(DR) is used, for example, to correct the Doppler phase rotation amount that is an integer multiple of 2π caused by the time difference of Doppler analysis between Loc Doppler analysis units 210.

[0240] For example, the folded phase correction vector β(DR) is represented as shown in equation (15).

[0241]

[0242]

[0243] For example, when Loc = 4, take integer values ​​of DR = -2, -1, 0, 1, and the folded phase correction vector β(DR) is expressed in the manner of equations (16), (17), (18), and (19).

[0244] β(-2)=[1,-1,1,-1] (16)

[0245]

[0246] β(0)=[1,1,1,1] (18)

[0247]

[0248] For example, when Loc=4, Figure 7 (a) or Figure 7 The output of the Doppler analysis unit 210, i.e., the Doppler frequency index f, is detected in (b). s_cfar The Doppler range of the Doppler components (e.g., -1 / 8Tr to +1 / 8Tr) corresponds to DR = 0. Furthermore, according to the Doppler frequency index f for DR = 0... s_cfar The Doppler phase rotation is an integer multiple of 2π (e.g., β(1), β(-1), and β(-2)). The folding determination unit 212 calculates the Doppler components corresponding to the Doppler range of DR=1 (e.g., 1 / 8Tr to 3 / 8Tr), the Doppler components corresponding to the Doppler range of DR=-1 (e.g., -3 / 8Tr to -1 / 8Tr), and the Doppler components corresponding to the Doppler range of DR=-2 (e.g., -1 / 2Tr to -3 / 8Tr and 3 / 8Tr to 1 / 2Tr).

[0249] Additionally, in equation (12), VFTALL z (f b_cfar f s_cfar For example, the output VFT of the Loc Doppler analysis unit 210 in the z-th antenna system processing unit 201 can be represented in vector form as shown in equation (20). z noc (f b f s The distance index f extracted in CFAR section 211 is compared with the distance index f in CFAR section 211. b_cfar and Doppler frequency index f s_cfar Corresponding component VFT z noc (f b_cfar f s_cfar (where noc = 1, ..., Loc).

[0250] VFTALL z (fb_cfar ,f s_cfar ) = [VFT z 1 (f b_cfar ,f s_cfar VFT z 2 (f b_cfar ,f s_cfar ...,VFT z Loc (f b_cfar ,f s_cfar )] (20)

[0252] For example, according to equation (12), the folding determination unit 212 calculates the unused orthogonal code UnCode, which corrects for the phase change of the Doppler component containing the fold, within the range of DR = ceil[-Loc / 2], ceil[-Loc / 2]+1, ..., 0, ..., ceil[Loc / 2]-1. nuc Received power after encoding separation DeMulUnCode nuc (f b_cfar f s_cfar ,DR).

[0253] Next, the folding determination unit 212 detects the received power DeMulUnCode in the range of each DR. nuc (f b_cfar f s_cfar The minimum DR is denoted by DR. The following equation (21) shows the received power DeMulUnCode within the range of each DR. nuc (f b_cfar f s_cfar The smallest DR is denoted as "DR". min ".

[0254]

[0255] The following explains why Doppler folding can be determined using the folding determination process described above.

[0256] For example, if the noise component is ignored, then the VFTALL shown in equation (20) z (f b_cfar f s_cfar The radar transmitted signal component contained in ) is transmitted from the nth transmitting antenna 106 (e.g., Tx#ncm) in the following manner as expressed by equation (22).

[0257]

[0258] Here, γz，ncm This represents the complex reflection coefficient of the radar signal transmitted from the nth transmitting antenna 106, after reflection from the target, when the signal is received by the zth antenna system processing unit 201. Additionally, DR... true The following index represents the true Doppler fold range: DR true Let ceil[-Loc / 2], ceil[-Loc / 2]+1, ..., 0, ..., ceil[Loc / 2]-1 be the index values. The following shows the index values ​​that can be set to DR. min =DR true The determination is made in this manner.

[0259] For the first to the Nth CM The radar signal components transmitted from each transmitting antenna 106 used UnCode (Unorthogonal Code). nuc The sum of the received power after encoding separation: PowDeMul(nuc, DR, DR) true ) is represented by the following formula (23).

[0260]

[0261] Furthermore, PowDeMul(nuc, DR, DR) shown in equation (23) true ) is equivalent to the one in equation (12) The evaluation value of the item.

[0262] In equation (23), DR = DR true In the case where orthogonal codes (UnCode) are not used nuc Orthogonal codes used for encoding and multiplexing transmission ncm The correlation between them is zero (e.g., UnCode). nuc * ·{Code ncm} T =0), therefore, PowDeMul(nuc, DR, DR) true ) = 0.

[0263] On the other hand, in equation (23), DR≠DR true In this case, the output depends Orthogonal codes used for encoding and multiplexing transmission ncm The correlation values ​​between PowDeMul(nuc, DR, DR) true ). Here, in all UnCode nuc PowDeMul(nuc, DR, DR) true If ) is not zero, for example, if the following equation (24) is satisfied and DR = DR trueIn the case of PowDeMul(nuc, DR) true DR true The power of ) is the lowest, and the folding determination unit 212 can detect DRtrue (=DR) min In other words, the folding determination unit 212 can perform Doppler folding determination according to equation (12).

[0264]

[0265] For example, in order to satisfy equation (24), as long as The item is not associated with other unused orthogonal keys (UnCode). nuc2 As long as they are consistent, that's fine. Here, nuc2 ≠ nuc.

[0266] Therefore, when only one orthogonal code is used, equation (24) is satisfied. Furthermore, when multiple orthogonal codes are used, for example, the encoding generation unit 104 can also make... If the selected item is not consistent with other unused orthogonal codes, choose the code for encoding multiplexing and transmission.

[0267] Here, when using codes such as Walsh-Hadamard codes or orthogonal M-sequence codes, sometimes an orthogonal code of code length Loc contains a group of codes whose odd-numbered coded elements are the same, while the signs of their even-numbered coded elements are reversed.

[0268] On the other hand, since β(0) = [1,1,…,1] and β(-Loc / 2) = [1,-1,1,-1,…,1,-1], therefore The item is converted to Uncode. nuc The odd-numbered encoding elements are the same, while the even-numbered encoding elements have their signs reversed.

[0269] Therefore, in the number of unused orthogonal keys (N) allcode -N CM In cases where there are two or more codes, for example, the encoding generation unit 104 may select the code for encoding multiplexing transmission or not use orthogonal codes in the following manner: that is, the codes in the orthogonal codes with code length Loc have one of the odd-numbered and even-numbered coding elements that are the same, while the group of codes with the sign reversed of the other coding element of the odd-numbered and even-numbered coding elements is not included in the unused orthogonal codes.

[0270] For example, a Walsh-Hadamard code with code length Loc = 4 contains WH4(1) = [1,1,1,1] and WH4(2) = [1,-1,1,-1]. or

[0271] Therefore, for example, the encoding generation unit 104 can also ensure that the groups of WH4(1) and WH4(2) are not included in multiple modes of not using orthogonal codes, and select the encoding for multiplexing transmission or not using orthogonal codes. In addition, WH4(3) = [1,1,-1,-1] and WH4(4) = [1,-1,-1,1] are also in the same relationship, so for example, the encoding generation unit 104 can also ensure that the groups of WH4(3) and WH4(4) are not included in multiple modes of not using orthogonal codes, and select the encoding for multiplexing transmission or not using orthogonal codes.

[0272] Furthermore, there are multiple unused orthogonal codes (UnCode). nuc In this case, it can also replace the received power DeMulUnCode. nuc (f b_cfar f s_cfar ,DR), in the manner of the following equation (25), utilizes the received power DeMulUnCodeAll(f) after coding separation using all unorthogonal codes. b_cfar f s_cfar ,DR).

[0273]

[0274] By calculating the received power after encoding separation using all unused orthogonal codes, the folding determination unit 212 can improve the folding determination accuracy even when the received signal level is low.

[0275] For example, the folding decision unit 212 calculates DeMulUnCodeAll(f) within the ranges of DR = ceil[-Loc / 2], ceil[-Loc / 2]+1, ..., 0, ..., ceil[Loc / 2]-1. b_cfar f s_cfar ,DR), detect received power DeMulUnCodeAll(f b_cfar f s_cfar The smallest DR (in other words, DR) min When using equation (25), the DR that gives the minimum received power within the DR range will be denoted as "DR" as shown in equation (26) below. min ".

[0276]

[0277] Alternatively, the folding determination unit 212 may also perform the following processing, for example, when comparing data using the unorthogonal code UnCode. nuc Minimum Received Power after Code Separation (DeMulUnCode) nuc (fb_cfar f s_cfar DR min The folding determination unit 212 can determine the certainty of the folding determination by measuring the received power and the folding power. In this case, the folding determination unit 212 can also determine the certainty of the folding determination by, for example, the following formulas (27) and (28).

[0278] DeMulUnCode nuc (f b_cfar ,f s_cfar ,DRmin)<Threshold DR ×PowerFT(f b_cfar ,f s_cfar ) (27)

[0280] DeMulUnCode nuc (f b_cfar ,f s_cfar ,DR min )≥Threshod DR ×PowerFT(f b_cfar ,f s_cfar ) (28)

[0282] For example, when using UnCode (not using orthogonal codes) nuc Minimum Received Power after Code Separation (DeMulUnCode) nuc (f b_cfar f s_cfar DR min The distance index f extracted in CFAR section 211 is less than 0. b_cfar and Doppler frequency index f s_cfar Received power value PowerFT(f b_cfar f s_cfar Multiply by the specified value Threshold DR If the obtained value is true (e.g., equation (27)), the folding determination unit 212 determines that the folding determination is sufficient. In this case, the radar device 10 may also perform subsequent processing (e.g., code separation processing).

[0283] On the other hand, for example, when using UnCode (not using orthogonal codes) nuc Minimum Received Power after Code Separation (DeMulUnCode) nuc (f b_cfar f s_cfar DR min ) equal to or greater than the received power value PowerFT(f b_cfar f s_cfarMultiply by Threshold DR If the obtained value is (for example, Equation (28)), the folding determination unit 212 determines that the accuracy of the folding determination is insufficient (for example, noise component). In this case, the radar device 10 may, for example, not perform subsequent processing (for example, code separation processing).

[0284] Through this process, the folding determination unit 212 can reduce the error in folding determination and remove noise components. Furthermore, the specified value Threshold... DR For example, it can be set in a range greater than 0 and less than 1. As another example, if noise components are taken into account, the Threshold can also be set in a range of approximately 0.1 to 0.5. DR .

[0285] Furthermore, there are multiple unused orthogonal codes (UnCode). nuc In the case of folding determination unit 212, it can also perform the following processing, that is, replace the received power DeMulUnCode. nuc (f b_cfar f s_cfar , DR), use DeMulUnCodeAll(f b_cfar f s_cfar The fold determination unit 212 compares the received power (DR) with the received power to determine (in other words, measure) the certainty of the fold determination. In this case, the fold determination unit 212 may also use DeMulUnCodeAll(f b_cfar f s_cfar ,DR) replaces DeMulUnCode in equations (27) and (28) nuc (f b_cfar f s_cfar The fold determination unit 212 determines the deterministic nature of the fold determination by calculating the received power after encoding separation using all unused orthogonal codes. Even when the received signal level is low, the fold determination unit 212 can improve the accuracy of the fold determination deterministic nature.

[0286] Furthermore, alternative equation (12) uses UnCode, which does not use orthogonal codes. nuc Received power after encoding separation DeMulUnCode nuc (f b_cfar f s_cfar The formula for calculating DR can also be, for example, the following formula (29).

[0287]

[0288] In equation (29), The item is an index that does not depend on the Doppler component (Doppler frequency index) fs Therefore, by pre-tabulating it, for example, the amount of computation in the folding decision unit 212 can be reduced.

[0289] The above describes an example of the operation of the folding determination unit 212.

[0290] Next, an example of the operation of the encoding multiplexing separation unit 213 will be explained.

[0291] The encoding multiplexing separation unit 213 performs encoding multiplexing signal separation processing based on the folding determination result in the folding determination unit 212 and the encoding used for encoding multiplexing transmission.

[0292] For example, the encoding multiplexing separation unit 213 uses the following formula (30) based on the fold determination result, i.e., DR, in the fold determination unit 212. min Folded phase correction vector β(DR) min ), for the distance index f extracted in CFAR section 211 b_cfar and Doppler frequency index f s_cfar The corresponding output of the Doppler analysis unit 210 is the Doppler component VFTALL. z (f b_cfar f s_cfar The encoding separation process is performed. The folding determination unit 212 can determine the index as the true Doppler folding range (in other words, it can determine the index as DR) within a Doppler range greater than or equal to -1 / (2Tr). min =DR true (The determination is made in a certain way). Therefore, the coding multiplexing separation unit 213 can set the correlation value between the orthogonal codes used for coding multiplexing to zero in the Doppler range of -1 / (2Tr) and less than 1 / (2Tr), thereby enabling separation processing that suppresses interference between the coding multiplexed signals.

[0293]

[0294] Here, DeMul z ncm (f b_cfar f s_cfar ) is the distance index f used by the Doppler analysis unit 210 in the z-th antenna system processing unit 201. b_cfar and Doppler frequency index f s_cfar The output orthogonal code Code ncm The output obtained by encoding and decoding the encoded multiplexed signal (e.g., the encoding and decoding result). Furthermore, z = 1, ..., Na, ncm = 1, ..., N CM (=N Tx ).

[0295] Through the coding separation process described above, the radar device 10 can obtain the result of the folding determination based on the folding determination unit 212's assumption of a Doppler range ±1 / (2Loc×Tr) that will not produce folding, and the result of the Doppler analysis unit 210's Loc multiple of the Doppler range ±1 / (2Loc×Tr), and obtain the orthogonal code Code assigned to the nth transmitting antenna Tx#ncm. ncm The signal obtained by encoding and multiplexing the transmitted signal and then separating it.

[0296] Additionally, during the encoding separation process, the radar device 10 performs Doppler phase correction (e.g., based on the folded phase correction vector β(DR)) on the output of the Doppler analysis unit 210 for each encoded element. min (processing). Therefore, the mutual interference between coded multiplexed signals can be reduced to, for example, the level of noise. In other words, the radar device 10 can reduce inter-symbol interference, thereby suppressing the effects of degradation on the detection performance of the radar device 10.

[0297] The above describes an example of the operation of the encoding multiplexing separation unit 213.

[0298] exist Figure 5 In the middle, the direction estimation unit 214 is based on the input from the coding multiplexing separation unit 213 for distance index f b_cfar Doppler frequency index f s_cfar The corresponding Doppler analysis unit 210 output encoding separation result DeMul z ncm (f b_cfar f s_cfar ), and perform target direction estimation processing.

[0299] Direction estimation unit 214 can, for example, use a pair of transmitting antennas 106 (e.g., ncm = 1, ..., N) Tx The signal DeMul obtained by encoding and decoding the transmitted encoded multiplexed signal. z ncm (f b_cfar f s_cfar Perform orientation estimation (DOA).

[0300] [Antenna Configuration Example]

[0301] In the radar device 10, for example, a configuration of transmitting antenna 106 and receiving antenna 202 is adopted, which utilizes a virtual receiving array to increase the aperture length, thereby improving angular resolution and suppressing grating lobes or sidelobes.

[0302] The following describes an example of the antenna configuration of the transmitting antenna 106 and the receiving antenna 202, and an example of the direction estimation processing in the direction estimation unit 214 when each configuration example is applied.

[0303] Furthermore, in the following configuration example, the radar device 10 can also have the configuration of the transmitting antenna 106 replaced with the configuration of the receiving antenna 202, and the configuration of the receiving antenna 202 replaced with the configuration of the transmitting antenna 106. Even when the antenna configurations of the transmitting antenna 106 and the receiving antenna 202 are swapped, the same effect as in the following configuration example can still be obtained in the radar device 10.

[0304] Alternatively, the radar device 10 can also be configured by swapping the horizontal direction (e.g., corresponding to the first direction) and the vertical direction (e.g., corresponding to the second direction orthogonal to the first direction) in the following configuration example. By swapping the horizontal and vertical directions in the antenna configuration, the radar device 10 can achieve the same effect as swapping the horizontal and vertical directions in the following configuration example.

[0305] The MIMO antenna configuration in this embodiment is, for example, a configuration that satisfies the conditions described below (e.g., condition 1 or condition 2). Condition 1 and condition 2 will be described below.

[0306] <Condition 1>

[0307] (1)N Tx Each transmitting antenna 106 is configured in a horizontal direction (e.g., corresponding to a first direction) and in a vertical direction (e.g., corresponding to a second direction orthogonal to the first direction). Furthermore, N Tx One of the transmitting antennas 106 is configured to be a configuration that is repeatedly included in both the transmitting antenna 106 configured in the horizontal direction and the transmitting antenna 106 configured in the vertical direction.

[0308] (2) Of the Na receiving antennas 202, excluding the Nz (Nz≧1) receiving antennas 202, the (Na-Nz) receiving antennas 202 are arranged in both the horizontal and vertical directions. Furthermore, the arrangement of one of the (Na-Nz) receiving antennas 202 is a configuration that is repeated in both the horizontally arranged receiving antennas 202 and the vertically arranged receiving antennas 202.

[0309] (3) The antenna spacing of the horizontally arranged transmitting antennas 106 is set to be larger than the aperture length of the horizontally arranged receiving antennas 202 (e.g., corresponding to the first antenna). Additionally, at least one antenna spacing of the horizontally arranged receiving antennas 202 is set to a basic horizontal spacing (or, referred to as a "prescribed spacing") D. H Furthermore, the antenna spacing of the transmitting antenna 106 and the antenna spacing of the receiving antenna 202 can be the spacing between the centers of the antennas, the spacing between the power supply points of the antennas, or the spacing based on the shape of the antennas (e.g., the spacing between the ends of the antennas, the spacing between the right ends of the antennas). Additionally, the spacing can also be referred to as distance.

[0310] (4) At least one of the Nz receiving antennas 202 (e.g., corresponding to the third antenna) is spaced at a basic horizontal interval D. H It is configured at a vertical position different from the vertical position (position on the vertical axis) of the receiving antenna 202 arranged in the horizontal direction, and at a horizontal position (position on the horizontal axis) adjacent to the receiving antenna 202 (e.g., the second antenna) arranged in the vertical direction.

[0311] The following is an example of condition 1.

[0312] Regarding condition 1(1), for example, N Tx The 106 transmitting antennas are in an "L" shape (N) Tx ≧3) "T" shape (N) Tx ≧4) or a "+" shape (N) Tx Any shape configuration of ≧5).

[0313] Figure 8 (a) represents N Tx An example of an "L"-shaped configuration when =6. Furthermore, in Figure 8 In (a), although it indicates an equally spaced configuration, it is not limited to this; it can also be an unequally spaced configuration. Additionally, N Tx The configuration of the transmitting antenna 106 can also be used to make Figure 8 The configuration in (a) is obtained by rotating it by any angle (e.g., 90°, 180°, 270°). Additionally, N... Tx The configuration of the transmitting antenna 106 can also be a configuration obtained by mirroring and reversing the above configuration.

[0314] In addition, Figure 8 In (a), Nt represents the number of antennas Nt of the transmitting antenna 106 arranged in the horizontal direction. H =4, and the number of antennas Nt arranged in the vertical direction V The case where Nt = 3, but NtH and Nt V The combinations are not limited to this. For example, as long as Nt H ≧2, Nt V ≥2, and satisfy Nt H +Nt V =N Tx A combination of +1 is sufficient. For example, N Tx Nt in the "L"-shaped configuration when =6 H With Nt V The combinations are (Nt) H Nt V The four possible combinations are (2, 5), (3, 4), (4, 3), and (5, 2).

[0315] Furthermore, in the "L"-shaped configuration, the number of transmitting antennas only needs to be N. Tx ≥3 is sufficient. Figure 8 (b) represents N Tx Example of an "L"-shaped configuration when =3.

[0316] then, Figure 9 (a) and Figure 9 (b) represents N Tx An example of a "T"-shaped configuration when =6. Furthermore, in Figure 9 (a) and Figure 9 In (b), although it indicates an equally spaced configuration, it is not limited to this; it can also be an unequally spaced configuration. Additionally, N Tx The configuration of the transmitting antenna 106 can also be used to make Figure 9 (a) and Figure 9 The configuration in (b) is obtained by rotating it by any angle (e.g., 90°, 180°, 270°). Additionally, N... Tx The configuration of the transmitting antenna 106 can also be a configuration obtained by mirroring and reversing the above configuration.

[0317] exist Figure 9 In (a), Nt represents the number of antennas Nt of the transmitting antenna 106 arranged in the horizontal direction. H =4, and the number of antennas Nt arranged in the vertical direction V In the case of =3, Figure 9 In (b), Nt represents the number of antennas Nt of the transmitting antenna 106 arranged in the horizontal direction. H =3, and the number of antennas Nt arranged in the vertical direction V The case where Nt = 4, but Nt H and Nt V The combinations are not limited to this. For example, as long as Nt H ≧2, Nt V≥2, and satisfy Nt H +Nt V =N Tx A combination of +1 is sufficient. For example, N Tx Nt in the "T"-shaped configuration when =6 H With Nt V The combinations are (Nt) H Nt V The four possible combinations are (2, 5), (3, 4), (4, 3), and (5, 2).

[0318] Furthermore, in the "T" configuration, the number of transmitting antennas only needs to be N. Tx ≥4 is sufficient. Figure 9 (c) represents N Tx Example of a "T"-shaped configuration when =4.

[0319] then, Figure 10 (a) represents N Tx An example of a cross-shaped configuration when =6. Furthermore, in Figure 10 In (a), although it indicates an equally spaced configuration, it is not limited to this; it can also be an unequally spaced configuration. Additionally, N Tx The configuration of the transmitting antenna 106 can also be used to make Figure 10 The configuration in (a) is obtained by rotating it by any angle (e.g., 90°, 180°, 270°). Additionally, N... Tx The configuration of the transmitting antenna 106 can also be a configuration obtained by mirroring and reversing the above configuration.

[0320] In addition, Figure 10 In (a), Nt represents the number of antennas Nt of the transmitting antenna 106 arranged in the horizontal direction. H =4, and the number of antennas Nt arranged in the vertical direction V The case where Nt = 3, but Nt H and Nt V The combinations are not limited to this. For example, as long as Nt H ≧3, Nt V ≥3, and satisfy Nt H +Nt V =N Tx A combination of +1 is sufficient. For example, N Tx Nt in the "+" shaped configuration when =6 H With Nt V The combinations are (Nt) H Nt V The two types are (3, 4) and (4, 3).

[0321] Furthermore, in the "+" configuration, the number of transmitting antennas only needs to be N.Tx A value of ≥5 is sufficient. Figure 10 (b) represents N Tx Example of a cross-shaped configuration when the value is 5.

[0322] The above provides examples related to condition (1).

[0323] Regarding condition 1 (2), for example, the (Na-Nz) receiving antennas 202 are configured in any of the following shapes: “L” (Na-Nz≧3), “T” (Na-Nz≧4), or “+” (Na-Nz≧5).

[0324] Furthermore, the configuration of the (Na-Nz) receiving antennas 202 can be the same shape as the transmitting antenna 106, or it can be a different shape. For example, if the transmitting antenna 106 is in an "L" shape, the receiving antennas 202 can be in an "L" shape, or they can be in a different shape (e.g., "T" shape, "+" shape). The combination of the configurations of the transmitting antenna 106 and the receiving antennas 202 is not limited to this, and other combinations of shapes are also possible.

[0325] Here, let Nr be the number of (Na-Nz) receiving antennas 202 arranged horizontally. H And set the number of antennas arranged in the vertical direction as Nr V In the case of "L" shaped and "T" shaped configurations, Nr H ≧2 and Nr V ≥2, In the case of a cross-shaped configuration, Nr H ≧3, Nr V ≥3, regardless of the configuration, Nr is satisfied. H +Nr V =Na-Nz+1.

[0326] The above provides examples related to condition (2) of condition 1.

[0327] Condition 1(3) is as follows: In the virtual receiving antenna configuration obtained based on the transmitting antenna 106 and the receiving antenna 202, the number Nt of antennas Nt arranged horizontally by the transmitting antenna 106 can be configured. H The number of antennas Nr arranged horizontally with respect to receiving antenna 202 H The product is Nt H ×Nr H The condition is that there are one antenna, and the maximum number of virtual receiving antennas can be configured in the horizontal direction without repetition.

[0328] Condition 1(4) is, for example, referred to as a "configuration condition for improving separation performance". Nz receiving antennas 202 or transmitting antennas 106 that satisfy the configuration condition for improving separation performance are referred to as "antennas for improving separation performance". Hereinafter, examples of configuration conditions for improving separation performance will be described.

[0329] Figure 11 This indicates that N is arranged in an "L" shape. Tx A diagram illustrating an example of six transmitting antennas 106 (e.g., Tx#1 to Tx#6) and six receiving antennas 202 (e.g., Rx#1 to Rx#6) arranged in an "L" shape, i.e., Na-Nz (=6). Figure 11 As shown, according to condition 1, for the receiving antenna 202 with a narrower antenna spacing in the vertical direction among the transmitting and receiving antennas, an antenna for improving separation performance can also be set.

[0330] exist Figure 11 In the diagram, the candidate configurations of the antennas that meet the configuration conditions for improving separation performance are the positions A, B, C, and D, indicated by dashed boxes.

[0331] For example, when Nz = 1, the total number of receiving antennas 202 is Na = 7, and the 1 (= Nz) unconfigured receiving antennas 202 are relative to... Figure 11 Either of the receiving antennas Rx#5 and Rx#6 shown is positioned at a fundamental interval D in the horizontal direction. H Adjacent configuration (in other words, configured at intervals of D) H (Location). That is, one unconfigured receiving antenna 202 is configured at... Figure 11 Any one of the positions A, B, C, or D within the dashed box shown. This satisfies the configuration conditions for improved separation performance.

[0332] By configuring Nz receiving antennas 202 in this position, the radar device 10 can reduce the influence of signal components between multiple waves when there are multiple target reflected waves, thereby improving separation performance (e.g., separation performance in the horizontal direction). Furthermore, examples of the effect of the radar device 10 on improving separation performance are illustrated using computer simulation results described later.

[0333] Furthermore, when Nz receiving antennas 202 (e.g., corresponding to the third antenna) are configured at a vertical position different from the vertical position of the receiving antennas 202 arranged in the horizontal direction (e.g., corresponding to the first antenna), and at a horizontal position adjacent to the receiving antennas 202 arranged in the vertical direction (e.g., corresponding to the second antenna), the Nz receiving antennas 202 can be configured on the side of the receiving antennas 202 arranged in the horizontal direction. Figure 11 (A, C) or the opposite side ( Figure 11 (B, D).

[0334] Here, with the receiving antenna 202 arranged in the horizontal direction ( Figure 11 Compared to cases A and C), if configured on the opposite side ( Figure 11 If B and D are used, the virtual receiving antenna configuration has the effect of increasing the horizontal antenna aperture and narrowing the horizontal beamwidth, thus further improving the resolution of the radar device 10. Furthermore, this configuration is more suitable for situations where antenna elements with large vertical dimensions are used.

[0335] On the other hand, compared to being configured on the opposite side ( Figure 11 Compared to cases B and D), if the antenna is positioned on the side arranged in the horizontal direction ( Figure 11 If A and C are present, the influence of signal components between multiple waves can be further reduced when there are multiple target reflected waves, thereby further improving the separation performance of the radar device 10 in the horizontal and vertical directions.

[0336] In addition, Figure 11 The text describes an "L"-shaped transceiver antenna, but for "T"-shaped or "+"-shaped antennas, for example, Nz receiving antennas 202 can be positioned horizontally on the side with more receiving antennas 202 arranged in the horizontal direction, relative to the position (horizontal position) of the multiple receiving antennas 202 arranged in the vertical direction. According to this configuration, for example, in the case of multiple target reflected waves, the influence of signal components between multiple waves can be further reduced. Similarly, for example, Nz receiving antennas 202 can be positioned horizontally on the side with fewer receiving antennas 202 arranged in the horizontal direction, relative to the position (horizontal position) of the multiple receiving antennas 202 arranged in the vertical direction. According to this configuration, for example, there is an effect of increasing the antenna aperture in the horizontal direction, and the beamwidth in the horizontal direction can be narrowed, thus improving the resolution of the radar device 10.

[0337] Additionally, for example, when Nz = 2, the total number of receiving antennas 202 is Na = 8, and at least one of the unconfigured 2 (= Nz) receiving antennas 202 is configured to meet the configuration conditions for improving separation performance (e.g., configured in...). Figure 11 (Any of positions A, B, C, and D in the dashed box). Furthermore, when configuring the two (=Nz) unconfigured receiving antennas to meet the configuration conditions for improved separation performance, for example, one receiving antenna 202 could be positioned with a basic horizontal spacing D. H ,and Figure 11 The Rx#5 shown is configured adjacently (configured in) Figure 11(either at point A or B), another receiving antenna 202 is positioned at a basic horizontal interval D. H ,and Figure 11 The Rx#6 shown is configured adjacently (configured in) Figure 11 (either at point C or D). According to this configuration, in the presence of multiple target reflected waves, the radar device 10 can further improve separation performance (e.g., in the horizontal direction).

[0338] Similarly, when Nz ≥ 3, at least one of the unconfigured Nz receiving antennas 202 can be configured to meet the configuration conditions for improving separation performance (e.g., configured in...). Figure 11 (Any of positions A, B, C, and D in the dashed box). Furthermore, for example, the more receiving antennas 202 among the Nz receiving antennas 202 that meet the configuration conditions for improved separation performance, the more effectively the influence between signal components among multiple waves can be reduced when there are multiple target reflected waves, thereby further improving the separation performance of the radar device 10.

[0339] The above provides an example of condition 1.

[0340] Furthermore, the configuration of the transmitting antenna 106 that satisfies condition 1 above can also be applied to the configuration of the receiving antenna 202, and the configuration of the receiving antenna 202 that satisfies condition 1 can be applied to the configuration of the transmitting antenna 106. Even in this case, the same effect as described above can be obtained. Hereinafter, the condition in this case will be referred to as "condition 1a". Thus, condition 1a is described below. Furthermore, the example of condition 1a is the same as the content after replacing the transmitting antenna and receiving antenna in the example of condition 1 above with receiving antenna and transmitting antenna respectively, so the explanation is omitted.

[0341] <Condition 1a>

[0342] (1) Na receiving antennas 202 are arranged in a horizontal direction (e.g., corresponding to a first direction) and in a vertical direction (e.g., corresponding to a second direction orthogonal to the first direction). Furthermore, the configuration of one of the Na receiving antennas 202 is a configuration that is repeatedly included in both the receiving antennas 202 arranged in the horizontal direction and the receiving antennas 202 arranged in the vertical direction.

[0343] (2)N Tx Of the 106 transmitting antennas, excluding Nz (Nz ≥ 1) other than the Nz transmitting antennas 106, Tx -Nz) transmitting antennas 106 are arranged in the horizontal and vertical directions. Furthermore, (N TxThe configuration of one of the transmitting antennas 106 (-Nz) is a configuration that is repeatedly included in both the transmitting antenna 106 configured in the horizontal direction and the transmitting antenna 106 configured in the vertical direction.

[0344] (3) The antenna spacing of the horizontally arranged receiving antennas 202 is set to be larger than the aperture length of the horizontally arranged transmitting antennas 106 (e.g., corresponding to the first antenna). Additionally, at least one antenna spacing among the horizontally arranged transmitting antennas 106 is set to a basic horizontal spacing (or, referred to as a "prescribed spacing") D. H .

[0345] (4) At least one of the Nz transmitting antennas 106 (e.g., corresponding to the third antenna) is spaced at a basic horizontal interval D. H It is configured at a vertical position different from the vertical position of the transmitting antenna 106 arranged in the horizontal direction (e.g., corresponding to the first antenna) and at a horizontal position adjacent to the transmitting antenna 106 arranged in the vertical direction (e.g., corresponding to the second antenna).

[0346] Figure 12 This is a diagram showing an example of an antenna configuration that satisfies condition 1a. Figure 12 This indicates that the receiving antenna 202 (e.g., Rx#1 to Rx#8) is configured in a "T" shape with Na=8, and N is configured in a "T" shape. Tx -Nz (=5) transmit antennas 106 (e.g., Tx#1~Tx#5). For example, as... Figure 12 As shown, according to condition 1a, for the transmitting antenna 106 with a narrower antenna spacing in the vertical direction among the transmitting and receiving antennas, an antenna for improving separation performance can be set.

[0347] exist Figure 12 In the diagram, the candidate configurations of the antennas that meet the configuration conditions for improving separation performance are the positions A, B, C, and D, indicated by dashed boxes.

[0348] For example, when Nz = 1, the total number of transmitting antennas 106 is N. Tx =6, 1 (=Nz) unconfigured transmit antennas 106 relative to Figure 12 Either of the transmitting antennas Tx#1 and Tx#3 shown is spaced at a basic horizontal interval D. H Adjacent configuration (in other words, configured at intervals of D) H (Location). That is, the unconfigured transmitting antenna 106 is configured at... Figure 12 Any one of the positions A, B, C, or D within the dashed box shown. This satisfies the configuration conditions for improved separation performance.

[0349] By configuring Nz transmitting antennas 106 in this position, the radar device 10 can reduce the influence of signal components between multiple waves when there are multiple target reflected waves, thereby improving separation performance (e.g., separation performance in the horizontal direction). Furthermore, examples of the effect of the radar device 10 on improving separation performance are illustrated using computer simulation results described later.

[0350] Furthermore, when Nz transmitting antennas 106 are configured in a vertical position different from the vertical position of the transmitting antennas 106 arranged in the horizontal direction, and in a horizontal position adjacent to the transmitting antennas 106 arranged in the vertical direction, the Nz transmitting antennas 106 can be configured on the side of the transmitting antennas 106 arranged in the horizontal direction. Figure 12 (B, D) or the opposite side ( Figure 12 (A, C).

[0351] Here, with respect to the transmitting antenna 106 arranged in the horizontal direction ( Figure 12 Compared to cases B and D, if configured on the opposite side ( Figure 12 If A and C are configured, the virtual receiving antenna configuration has the effect of increasing the horizontal antenna aperture and narrowing the horizontal beamwidth, thus further improving the resolution of the radar device 10. Furthermore, this configuration is more suitable for situations where antenna elements with large vertical dimensions are used.

[0352] On the other hand, compared to being configured on the opposite side ( Figure 12 Compared to cases A and C), if it is configured on the side of the antenna arranged in the horizontal direction ( Figure 12 If B and D are present, then in the case of multiple target reflected waves, the influence between the signal components of multiple waves can be further reduced, thereby further improving the separation performance of the radar device 10 in the horizontal and vertical directions.

[0353] Additionally, for example, when Nz = 2, the total number of transmitting antennas 106 is N. Tx =7, at least one of the two (=Nz) unconfigured transmit antennas 106 is configured to meet the configuration conditions for improving separation performance (e.g., configured in...). Figure 12 (Any of positions A, B, C, and D in the dashed box). Furthermore, when configuring the two (=Nz) unconfigured transmit antennas to meet the configuration conditions for improved separation performance, for example, one transmit antenna 106 could be positioned at a basic horizontal spacing D. H ,and Figure 12 The Tx#1 shown is configured adjacently (configured in) Figure 12(either at point A or B), another transmitting antenna 106 is positioned at a basic horizontal spacing D. H ,and Figure 12 The Tx#3 shown is configured adjacently (configured in) Figure 12 (either at point C or D). According to this configuration, in the presence of multiple target reflected waves, the radar device 10 can further improve separation performance (e.g., in the horizontal direction).

[0354] Similarly, when Nz ≥ 3, at least one of the unconfigured Nz transmit antennas 106 can be configured to meet the configuration conditions for improving separation performance (e.g., configured in...). Figure 12 (Any of positions A, B, C, and D in the dashed box). Furthermore, for example, the more transmit antennas 106 among the Nz transmit antennas 106 that meet the configuration conditions for improved separation performance, the more effectively the influence between signal components among multiple waves can be reduced when there are multiple target reflected waves, thereby further improving the separation performance of the radar device 10.

[0355] Furthermore, the same effect can be achieved by replacing the horizontal direction in conditions 1 and 1a with the vertical direction, and vice versa.

[0356] <Condition 2>

[0357] Condition 2 is, for example, the same as the result of changing the horizontal direction of Condition 1 to the vertical direction and then changing the vertical direction to the horizontal direction.

[0358] (1)N Tx Each transmitting antenna 106 is configured in a horizontal direction (e.g., corresponding to a second direction) and in a vertical direction (e.g., corresponding to a first direction). Furthermore, N Tx The configuration of one of the transmitting antennas 106 is a configuration that is repeatedly included in both the transmitting antenna 106 configured in the horizontal direction and the transmitting antenna 106 configured in the vertical direction.

[0359] (2) Of the Na receiving antennas 202, excluding the Nz (Nz≧1) receiving antennas 202, the (Na-Nz) receiving antennas 202 are arranged in both the horizontal and vertical directions. Furthermore, the arrangement of one of the (Na-Nz) receiving antennas 202 is a configuration that is repeated in both the horizontally arranged receiving antennas 202 and the vertically arranged receiving antennas 202.

[0360] (3) The antenna spacing of the vertically arranged transmitting antennas 106 is set to be larger than the aperture length of the vertically arranged receiving antennas 202 (e.g., corresponding to the first antenna). Additionally, at least one antenna spacing among the vertically arranged receiving antennas 202 is set to a basic vertical spacing D. V .

[0361] (4) At least one of the Nz receiving antennas 202 (e.g., corresponding to the third antenna) is spaced at a fundamental interval D in the vertical direction. V It is configured at a horizontal position different from the horizontal position of the receiving antenna 202 (e.g., corresponding to the first antenna) arranged in the vertical direction, and at a vertical position adjacent to the receiving antenna 202 (e.g., corresponding to the second antenna) arranged in the horizontal direction.

[0362] Figure 13 This indicates that N is arranged in an "L" shape. Tx A diagram illustrating an example of six transmitting antennas (e.g., Tx#1 to Tx#6) and six receiving antennas (e.g., Rx#1 to Rx#6) arranged in an "L" shape, namely Na-Nz (=6). Figure 13 As shown, according to condition 2, for the receiving antenna 202 with a narrower antenna spacing in the horizontal direction among the transmitting and receiving antennas, an antenna for improving separation performance can be set.

[0363] exist Figure 13 In the diagram, the candidate configurations of the antennas that meet the configuration conditions for improving separation performance are the positions A, B, C, and D, indicated by dashed boxes.

[0364] For example, when Nz = 1, the total number of receiving antennas 202 is Na = 7, and the 1 (= Nz) unconfigured receiving antennas 202 relative to... Figure 13 Either of the receiving antennas Rx#1 and Rx#2 shown is spaced at a fundamental interval D in the vertical direction. V Adjacent to each other (in other words, located at a distance of D) V (Location). That is, one unconfigured receiving antenna 202 is configured at... Figure 13 Any one of the positions A, B, C, or D within the dashed box shown. This satisfies the configuration conditions for improved separation performance.

[0365] By configuring Nz receiving antennas 202 in this position, the radar device 10 can reduce the influence of signal components between multiple waves when there are multiple target reflected waves, thereby improving separation performance (e.g., vertical separation performance). Furthermore, examples of the radar device 10's effect on improving separation performance will be illustrated using computer simulation results described later.

[0366] Furthermore, when Nz receiving antennas 202 (e.g., corresponding to the third antenna) are configured at a horizontal position different from the horizontal position of the receiving antennas 202 arranged in the vertical direction (e.g., corresponding to the first antenna), and at a vertical position adjacent to the receiving antennas 202 arranged in the horizontal direction (e.g., corresponding to the second antenna), the Nz receiving antennas 202 can be configured on the side of the receiving antennas 202 arranged in the vertical direction. Figure 13 (A, C) or the opposite side ( Figure 13 (B, D).

[0367] Here, on the side of the receiving antenna 202 arranged in the vertical direction ( Figure 13 Compared to A and C), if they are configured on the opposite side ( Figure 13 If B and D are used, the virtual receiving antenna configuration has the effect of increasing the antenna aperture in the vertical direction and narrowing the beamwidth in the vertical direction, thus further improving the resolution of the radar device 10. Furthermore, this configuration is more suitable for situations where antenna elements with large horizontal dimensions are used.

[0368] On the other hand, compared to being configured on the opposite side ( Figure 13 Compared to cases B and D), if it is configured on the side of the antenna arranged in the vertical direction ( Figure 13 If A and C are present, then in the case of multiple target reflected waves, the influence between the signal components of multiple waves can be further reduced, thereby further improving the vertical and horizontal separation performance of the radar device 10.

[0369] In addition, Figure 13 The text describes an "L"-shaped transceiver antenna, but for "T"-shaped or "+"-shaped antennas, for example, Nz receiving antennas 202 can be positioned vertically on the side with more receiving antennas 202 arranged in the vertical direction, relative to the position (vertical position) of the multiple receiving antennas 202 arranged in the horizontal direction. According to this configuration, for example, in the case of multiple target reflected waves, the influence of signal components between multiple waves can be further reduced. Similarly, for example, Nz receiving antennas 202 can be positioned vertically on the side with fewer receiving antennas 202 arranged in the horizontal direction, relative to the position (vertical position) of the multiple receiving antennas 202 arranged in the horizontal direction. According to this configuration, for example, there is an effect of increasing the antenna aperture in the horizontal direction, and the beamwidth in the horizontal direction can be narrowed, thus improving the resolution of the radar device 10.

[0370] Additionally, for example, when Nz = 2, the total number of receiving antennas 202 is Na = 8, and at least one of the unconfigured 2 (= Nz) receiving antennas 202 is configured to meet the configuration conditions for improving separation performance (e.g., configured in...). Figure 13 (Any of positions A, B, C, and D in the dashed box). Furthermore, when configuring the two (=Nz) unconfigured receiving antennas to meet the configuration conditions for improved separation performance, for example, one receiving antenna 202 could be positioned with a basic vertical spacing D. V ,and Figure 13 The Rx#1 shown is configured adjacently (configured in) Figure 13 (either at point A or B), another receiving antenna 202 is positioned at a fundamental vertical spacing D. V ,and Figure 13 The Rx#2 shown is configured adjacently (configured in) Figure 13 (either at point C or D). According to this configuration, in the presence of multiple target reflections, the radar device 10 can further improve separation performance (e.g., in the vertical direction).

[0371] Similarly, when Nz ≥ 3, at least one of the unconfigured Nz receiving antennas 202 can be configured to meet the configuration conditions for improving separation performance (e.g., configured in...). Figure 13 (Any of positions A, B, C, and D in the dashed box). Furthermore, for example, the more receiving antennas 202 among the Nz receiving antennas 202 that meet the configuration conditions for improved separation performance, the more effectively the influence between signal components among multiple waves can be reduced when there are multiple target reflected waves, thereby further improving the separation performance of the radar device 10.

[0372] The above provides an example of condition 2.

[0373] <Condition 2a>

[0374] Condition 2a is, for example, the same as the condition 1a above, where the horizontal direction is replaced with the vertical direction and the vertical direction is replaced with the horizontal direction.

[0375] (1) Na receiving antennas 202 are configured in a horizontal direction (e.g., corresponding to a second direction) and in a vertical direction (e.g., corresponding to a first direction). Furthermore, the configuration of one of the Na receiving antennas 202 is a configuration that is repeatedly included in both the receiving antenna 202 configured in the horizontal direction and the receiving antenna 202 configured in the vertical direction.

[0376] (2)N TxOf the 106 transmitting antennas, excluding Nz (Nz ≥ 1) other than the Nz transmitting antennas 106, Tx -Nz) transmitting antennas 106 are arranged in the horizontal and vertical directions. Furthermore, (N Tx The configuration of one of the transmitting antennas 106 (-Nz) is a configuration that is repeatedly included in both the transmitting antenna 106 configured in the horizontal direction and the transmitting antenna 106 configured in the vertical direction.

[0377] (3) The antenna spacing of the receiving antennas 202 arranged in the vertical direction is set to be larger than the aperture length of the transmitting antennas 106 arranged in the vertical direction (e.g., corresponding to the first antenna). Furthermore, at least one antenna spacing among the transmitting antennas 106 arranged in the vertical direction is set to a basic vertical spacing (or, referred to as a "prescribed spacing") D. V .

[0378] (4) At least one of the Nz transmitting antennas 106 (e.g., corresponding to the third antenna) is spaced at a fundamental interval D in the vertical direction. V It is configured at a horizontal position different from the horizontal position of the transmitting antenna 106 (e.g., the first antenna) arranged in the vertical direction, and at a vertical position adjacent to the transmitting antenna 106 (e.g., corresponding to the second antenna) arranged in the horizontal direction.

[0379] Figure 14 This is a diagram showing an example of an antenna configuration that satisfies condition 2a. Figure 14 This indicates that the receiving antenna 202 (e.g., Rx#1 to Rx#8) is arranged in a cross shape with Na=8, and N is arranged in a cross shape. Tx -Nz (=5) transmit antennas 106 (e.g., Tx#1~Tx#5). For example, as... Figure 14 As shown, according to condition 2a, for the transmitting antenna 106 with a narrower horizontal antenna spacing in the transmitting and receiving antennas, an antenna for improving separation performance can be set.

[0380] exist Figure 14 In the diagram, the candidate configurations of the antennas that meet the configuration conditions for improving separation performance are the positions A, B, C, and D, indicated by dashed boxes.

[0381] For example, when Nz = 1, the total number of transmitting antennas 106 is N. Tx =6, 1 (=Nz) unconfigured transmit antennas 106 relative to Figure 14 Either of the transmitting antennas Tx#2 and Tx#5 shown is spaced at a fundamental vertical spacing D. V Adjacent configuration. That is, the unconfigured transmit antenna 106 is configured in... Figure 14 Any one of the positions A, B, C, or D within the dashed box shown. This satisfies the configuration conditions for improved separation performance.

[0382] By configuring Nz transmitting antennas 106 in this position, the radar device 10 can reduce the influence of signal components between multiple waves when there are multiple target reflected waves, thereby improving separation performance (e.g., vertical separation performance). Furthermore, examples of the radar device 10's effect on improving separation performance are illustrated using computer simulation results described later.

[0383] Additionally, for example, when Nz = 2, the total number of transmitting antennas 106 is N. Tx =7, at least one of the two (=Nz) unconfigured transmit antennas 106 is configured to meet the configuration conditions for improving separation performance (e.g., configured in...). Figure 14 (Any of positions A, B, C, and D within the dashed box). Furthermore, when configuring the two (=Nz) unconfigured transmit antennas to meet the conditions for improved separation performance, for example, one transmit antenna 106 could be positioned with a basic vertical spacing D. V ,and Figure 14 The Tx#2 shown is configured adjacently (configured in) Figure 14 (either at point A or B), another transmitting antenna 106 is positioned at a fundamental vertical spacing D. V ,and Figure 14 The Tx#5 shown is configured adjacently (configured in) Figure 14 (either at point C or D). According to this configuration, in the presence of multiple target reflections, the radar device 10 can further improve separation performance (e.g., in the vertical direction).

[0384] Similarly, when Nz ≥ 3, at least one of the unconfigured Nz transmit antennas 106 can be configured to meet the configuration conditions for improving separation performance (e.g., configured in...). Figure 14 (Any of positions A, B, C, and D in the dashed box). Furthermore, for example, the more transmit antennas 106 among the Nz transmit antennas 106 that meet the configuration conditions for improved separation performance, the more effectively the influence between signal components among multiple waves can be reduced when there are multiple target reflected waves, thereby further improving the separation performance of the radar device 10.

[0385] The above explains conditions 2 and 2a.

[0386] In addition, Figure 14In the case of the antenna configuration shown, the configuration that satisfies condition 1 (or condition 1a) for improved separation performance can also be any of the configurations at positions A, B, C, and D in the dashed box. Sometimes, some or all of the configurations that satisfy conditions 1 and 2 for improved separation performance will be the same. In the case of multiple target reflected waves, this configuration that satisfies both conditions 1 and 2 for improved separation performance can further reduce the influence of signal components between multiple waves, and can further improve the separation performance of the radar device 10. Therefore, for example, the configuration that satisfies both conditions 1 and 2 for improved separation performance can also be preferentially applied to Nz antenna configurations.

[0387] Similarly, in the case of multiple target reflected waves, a configuration that satisfies both conditions 1a and 2a to improve separation performance can further reduce the influence of signal components between multiple waves, and can further improve the separation performance of the radar device 10. Therefore, for example, a configuration that satisfies both conditions 1a and 2a to improve separation performance can also be preferentially used as an Nz antenna configuration.

[0388] As described above, depending on the configuration that satisfies condition 1 (or condition 1a), the radar device 10 can improve its separation performance when receiving reflected waves from targets with different angles of arrival. Condition 1 (or condition 1a) is, for example, a condition that can also improve separation performance in the vertical direction, but prioritizes improving separation performance in the horizontal direction.

[0389] Furthermore, depending on the configuration that satisfies condition 2 (or condition 2a), the radar device 10 can improve its separation performance when receiving reflected waves from targets with different angles of arrival. Condition 2 (or condition 2a) is, for example, a condition that can also improve separation performance in the horizontal direction, but prioritizes improving separation performance in the vertical direction.

[0390] For example, in the antenna configuration of radar device 10, if the aperture of the virtual receiving antenna in the horizontal direction is larger than the aperture of the virtual receiving antenna in the vertical direction, since fewer virtual antennas are arranged in the vertical direction, condition 1 (or condition 1a) is more suitable than condition 2 (or condition 2a). Even with fewer antennas Nz used to improve separation performance, a greater improvement in separation performance can be achieved. On the other hand, for example, in the antenna configuration of radar device 10, if the aperture of the virtual receiving antenna in the vertical direction is larger than the aperture of the virtual receiving antenna in the horizontal direction, since fewer virtual antennas are arranged in the horizontal direction, condition 2 (or condition 2a) is more suitable than condition 1 (or condition 1a). Even with fewer antennas Nz used to improve separation performance, a greater improvement in separation performance can be achieved.

[0391] The above explains conditions 1 and 2 respectively.

[0392] Furthermore, as an example, in conditions 1 and 1a (or conditions 2 and 2a), an antenna for improving separation performance can be set for antennas with narrower antenna spacing in the vertical (or horizontal) direction of the transmitting and receiving antennas. Moreover, even if the antenna is configured in a position other than the antennas shown in the figures, the effects described above can still be achieved.

[0393] Next, an example of an antenna configuration that satisfies condition 1 (e.g., a MIMO antenna configuration example) and an example of a direction estimation result obtained by computer simulation will be described.

[0394] <Configuration Example 1>

[0395] Figure 15 (a) is a diagram showing a configuration example (e.g., a MIMO antenna configuration example) of the transmitting antenna 106 (e.g., referred to as "Tx") and the receiving antenna 202 (e.g., referred to as "Rx") of configuration example 1.

[0396] exist Figure 15 In the example shown in (a), the number of transmitting antennas N Tx There are 4 receiving antennas (e.g., Tx#1, Tx#2, Tx#3, and Tx#4), and the number of receiving antennas Na is 4 (e.g., Rx#1, Rx#2, Rx#3, and Rx#4). Furthermore, among the receiving antennas, antenna Rx#4 has Nz = 1.

[0397] Figure 15 (b) indicates that according to Figure 15 The diagram shows an example of the configuration of a virtual receiving array obtained by the antenna configuration shown in (a).

[0398] Here, the configuration of the virtual receiving array may be represented, for example, based on the location of the transmitting antenna 106 constituting the transmitting array antenna (e.g., the location of the power supply point) and the location of the receiving antenna 202 constituting the receiving array antenna (e.g., the location of the power supply point), as in the following formula (31).

[0399]

[0400] Here, the position coordinates of the transmitting antenna 106 (e.g., Tx#n) constituting the transmitting array antenna are described as "(X T_#n ,Y T_#n (For example, n = 1, ..., N) Tx The position coordinates of the receiving antenna 202 (e.g., Rx#m) constituting the receiving array antenna are described as "(X R_#m ,Y R_#m(e.g., m = 1, ..., Na), the position coordinates of the virtual antenna VA#k that constitutes the virtual receiving array antenna are described as "(X V_#k ,Y V_#k (For example, k = 1, ..., N) Tx ×Na).

[0401] Furthermore, in equation (31), for example, VA#1 is denoted as “the location reference (0, 0) of the virtual receiving array”.

[0402] exist Figure 15 In (a), the transmitting antennas Tx#1 to Tx#4 are configured in an "L" shape. For example, Tx#1 to Tx#3 are arranged horizontally, and Tx#1 and Tx#4 are arranged vertically (e.g., equivalent to (1) in condition 1). For example, the position coordinates (X) relative to Tx#1 T_#1 ,Y T_#1 The position coordinates of Tx#2 to Tx#4 are respectively (X T_#2 Y T_#2 )=(X T_#1 +2D H ,Y T_#1 ), (X T_#3 ,Y T_#3 )=(X T_#1 +4D H ,Y T_#1 ), (X T_#4 ,Y T_#4 )=(X T_#1 ,Y T_#1 +2D V Here, the antenna spacing of the horizontally arranged transmitting antennas Tx#1 to Tx#3 is greater than the aperture length D of the horizontally arranged receiving antennas 202. H Larger intervals (e.g., equivalent to condition 1(3)). Additionally, in Figure 15 In (a), the antenna spacing of the transmitting antennas Tx#1 and Tx#4 arranged in the vertical direction is greater than the aperture length D of the receiving antenna 202 arranged in the vertical direction. V Larger spacing configurations are possible, but not limited to this.

[0403] On the other hand, Figure 15 In (a) shown, among the receiving antennas Rx#1 to Rx#4 with Na=4, the three (=Na-Nz) receiving antennas Rx#1 to Rx#3 other than the antenna Rx#4 with Nz=1 are arranged in an "L" shape (e.g., equivalent to (2) of condition 1). The antenna spacing between the horizontally arranged receiving antennas Rx#1 and Rx#2 includes the basic horizontal spacing D.H .

[0404] For example, Figure 15 The receiving antennas Rx#1 to Rx#3 shown in (a) are configured such that the "L" shape is reversed horizontally. Rx#1 to Rx#2 are arranged horizontally, while Rx#2 and Rx#3 are arranged vertically. For example, the position coordinates (X) relative to Rx#1... R_#1 ,Y R_#1 The position coordinates of Rx#2 to Rx#3 are respectively (X R_#2 ,Y R_#2 )=(X R_#1 +D H ,Y R_#1 ), (X R_#3 ,Y R_#3 )=(X R_#1 +D H ,Y R_#1 +D V ).

[0405] In addition, Figure 15 In (a), the receiving antenna Rx#4 (e.g., an antenna for improving separation performance) corresponding to Nz=1 is spaced at a basic horizontal spacing D. H It is positioned perpendicular to the horizontally arranged receiving antennas Rx#1 and Rx#2 (Y). R_#1 Different vertical positions (Y) R_#1 +D V ), and the horizontal position adjacent to the vertically arranged receiving antennas Rx#2 and Rx#3 (e.g., equivalent to condition 1 (4)). That is, the position coordinates of Rx#4 (X R_#4 ,Y R_#4 )=(X R_#1 +2D H ,Y R_#1 +D V ).

[0406] Furthermore, the following situation is explained, namely, in Figure 15 In the antenna configuration shown in (a), when the Nz receiving antennas, i.e., Rx#4, which improve the separation performance, are positioned at a position perpendicular to the horizontally arranged receiving antennas Rx#1 and Rx#2 (Y),... R_#1 Different vertical positions (Y) R_#1 +D V When the receiving antenna Rx#4 is positioned horizontally adjacent to the receiving antenna Rx#3, it is positioned on the opposite side of the horizontally arranged receiving antennas, i.e., the position coordinates (X) of Rx#4. R_#4 ,Y R_#4 )=(XR_#1 +2D H ,Y R_#1 +D V This is one possible scenario, but not a limitation. For example, the receiving antenna Rx#4 can also be configured on the side of receiving antennas arranged in the horizontal direction, i.e., the position coordinates of Rx#4 (X...) R_#4 Y R_#4 )=(X R_#1 Y R_#1 +D V ) place.

[0407] so, Figure 15 The MIMO antenna configuration shown in (a) is configured to satisfy the above (condition 1).

[0408] according to Figure 15 The configuration of transmitting antennas Tx#1 to Tx#4 and receiving antennas Rx#1 to Rx#4 shown in (a) constitutes Figure 15 The position coordinates of the virtual antennas VA#1 to VA#16 of the virtual receiving array shown in (b) can be calculated by equation (31). For example, the position coordinates of the virtual antennas VA#1 to VA#16 are respectively (X V_#1 ,Y V_#1 )=(0,0), (X V_#2 ,Y V_#2 )=(D H ,0), (X V_#3 ,Y V_#3 )=(D H D V ), (X V_#4 ,Y V_#4 )=(2D H D V ), (X V_#5 ,Y V_#5 )=(2D H ,0), (X V_#6 ,Y V_#6 )=(3D H ,0), (X V_#7 ,Y V_#7 )=(3D H D V ), (X V_#8 ,Y V_#8 )=(4D H D V ), (X V_#9 ,Y V_#9 )=(4D H ,0), (X V_#10 ,Y V_#10 )=(5D H,0), (X V_#11 ,Y V_#11 )=(5D H D V ), (X V_#12 ,Y V_#12 )=(6D H D V ), (X V_#13 ,Y V_#13 )=(0,2D V ), (X V_#14 ,Y V_#14 )=(D H 2D V ), (X V_#15 ,Y V_#15 )=(D H 3D V ), (X V_#16 ,Y V_#16 )=(2D H 3D V ).

[0409] Here, the NTx transmitting antennas 106 are arranged in an "L" shape (N Tx ≧3) "T" shape (N) Tx ≧3) or "+" shape (N) Tx If any of the Na receiving antennas 202 are configured in any shape (≥4), and the (Na-Nz) receiving antennas other than the Nz (Nz≧1) receiving antennas are configured in any of the following shapes: “L” (Na-Nz≧3), “T” (Na-Nz≧4), or “+” (Na-Nz≧5), then if the number of horizontally arranged antennas in the transmitting antenna 106 is set to Nt... H The number of antennas arranged in the vertical direction will be set as Nt. V Let Nr be the number of antennas arranged horizontally in the receiving antenna 202. H And the number of antennas arranged in the vertical direction will be set as Nr. V Then it becomes the condition that satisfies Nt H +Nt V =N Tx +1、Nr H +Nr V =Na-Nz+1. For example, in Figure 15 In case (a), Nt H =3, Nt V =2, Nr H =2, Nr V =2, Nt H +Nt V =5, Nr H +Nr V=4, which satisfies the above formula.

[0410] In addition, Figure 15 In (a), the antenna spacing D of the transmitting antennas 106 arranged in the horizontal direction TH The number of antennas Nr arranged horizontally is set to be greater than that of the receiving antenna 202. H The value of (=2)-1 and the antenna spacing D RH =D H The product of D RH ×(Nr H -1)=D H Based on this setting, the following is constituted: Figure 15 The number of virtual antennas Nv arranged horizontally in the virtual receiver array antenna shown in (b) H For Nt H ×Nr H Components (in) Figure 15 (in (b), there are 6 elements: VA#1, VA#2, VA#5, VA#6, VA#9, and VA#10). In other words, according to the above settings, virtual antennas VA#1, VA#2, VA#5, VA#6, VA#9, and VA#10 arranged horizontally can be configured without repetition.

[0411] Additionally, for example, the antenna spacing DTH is set to the number Nr of the receiving antennas 202 arranged in the horizontal direction. H (=2) and antenna spacing D RH =D H The product of D RH ×Nr H (=2D H Thus, the Nt antennas arranged horizontally in the virtual receiving array antenna constitute the antenna. H ×Nr H The virtual antennas, consisting of (=6) elements, are spaced at equal intervals D RH =D H They are arranged in a straight line.

[0412] Similarly, in Figure 15 In (a), the antenna spacing D of the transmitting antennas 106 arranged in the vertical direction TV The number of antennas Nr arranged vertically is set to be greater than that of the receiving antenna 202. V The value of (=2)-1 and the antenna spacing D RV =D V The product of D RV ×(Nr V -1)=D V Based on this setting, the following is constituted: Figure 15The number of virtual antennas Nv arranged vertically in the virtual receiver array antenna shown in (b) V For Nt V ×Nr V Components (in) Figure 15 (in (b), there are four elements: VA#2, VA#3, VA#14, and VA#15). In other words, according to the above settings, virtual antennas VA#2, VA#3, VA#14, and VA#15 arranged vertically can be configured without repetition.

[0413] Additionally, for example, the antenna spacing D TV The number of antennas Nr arranged vertically as receiving antenna 202 V (=2) and antenna spacing D RV =D V The product of D RV ×Nr V (=2D V Thus, the Nt antennas arranged vertically in the virtual receiving array antenna constitute the antenna. V ×Nr V The virtual antennas with (=4) elements are spaced at equal intervals D RV =D V They are arranged in a straight line.

[0414] Here, D H D V These are the basic spacing in the horizontal direction and the basic spacing in the vertical direction, respectively, and are spacings shorter than the wavelength (λ) of the radar signal transmitted. For example, D H D V It can be set to approximately 0.45λ to 0.8λ (in other words, any value within the range of 0.45λ to 0.8λ). Furthermore, λ represents the wavelength of the carrier frequency of the radar transmitted signal. For example, when using a chirped signal as the radar transmitted signal, λ is the wavelength of the center frequency of the chirped signal's frequency scan band.

[0415] Thus, in a virtual receiver array configuration consisting of MIMO antenna configurations satisfying condition 1 (for example, the same applies in the cases of conditions 1a, 2, and 2a), the product of the number of each element of the virtual receiver antenna arranged in the horizontal and vertical directions is Nv. H ×Nv V =Nt H ×Nr H ×Nt V ×Nr V Additionally, depending on the "L" shape (or "T" shape, "+" shape) configuration, the transmitting and receiving antennas are Nt respectively. H >1, Nt V>1, Nr H >1, Nr V >1. Therefore, the number of components in the virtual receiving antenna is greater than the product of the number of transmitting and receiving antennas, N. Tx ×Na (e.g., Nv) H ×Nv V >N Tx ×Na). Therefore, it is possible to improve the effect of increasing the number of components in the vertical direction and the number of components in the horizontal direction of the virtual receiving antenna.

[0416] Next, an example of the direction estimation processing in the direction estimation unit 214 when the above-described antenna configuration is applied will be described.

[0417] For example, the direction estimation unit 214 uses the received signal DeMul obtained by performing encoding and decoding processing on the coded multiplexed signal transmitted from the transmitting antenna 106. z ncm (f b_cfar ,f s_cfar The virtual receiver array correlation vector h(f) of the transmitting antenna 106 shown in Equation (32) b_cfar ,f s_cfar ), and perform direction estimation processing.

[0418] Virtual receiver array correlation vector h(f) b_cfar ,f s_cfar (Includes the number of transmitting antennas N) Tx The product of this and the number of receiving antennas Na is N. Tx ×Na elements. Virtual receiver array correlation vector h(f) b_cfar ,f s_cfar This is used for direction estimation of the reflected wave signal from the target based on the phase difference between each receiving antenna 202. Here, z = 1, ..., Na. For the MIMO antenna configuration of Configuration Example 1, for example, when using... Figure 15 In case (a), due to N Tx =4, Na=4, virtual receiver array correlation vector h(f b_cfar ,f s_cfar It contains 16 elements, each element corresponding to Figure 15 The received signals of VA#1 to VA#16 in the virtual receiving antenna configuration shown in (b).

[0419]

[0420] Next, the direction estimation unit 216 uses the received signal of the virtual receiving array configured by the above-described transceiver antennas, i.e., the virtual receiving array correlation vector h(f) b_cfar ,f s_cfar The horizontal and vertical directions are estimated in the following manner.

[0421] For example, the virtual receiver array element number (VA# number) mentioned above corresponds to the virtual receiver array correlation vector h(f) shown in equation (32). b_cfar ,f s_cfar The element number of the column vector of ). For example, VA#1 corresponds to h(f b_cfar ,f s_cfar The first element of the column vector element DeMul1 1 (f b_cfar ,f s_cfar ).

[0422] The direction estimation unit 214, for example, uses the following formula (33) to correct the phase and amplitude deviations between the transmitting array antennas and between the receiving array antennas, using the array correction value h_cal. [y] Multiply by the virtual array correlation vector h(f) b_cfar ,f s_cfar Thus, the virtual receiver array correlation vector h, which corrects for inter-antenna misalignment, is output. _after_cal (f b_cfar ,f s_cfar Based on the phase difference between the receiving antennas receiving the reflected wave, direction estimation is performed in the horizontal and vertical directions. Here, y = 1, ..., (N) Tx ×Na).

[0423] Furthermore, in equation (33), CA is, as shown in equation (34), an array correction coefficient that corrects the phase and amplitude deviations between transmitting and receiving antennas, and a coefficient that reduces the influence of inter-element coupling between antennas (N). Tx A square matrix of order (×Na). When the coupling between antennas in the virtual receiver array can be ignored, CA becomes a diagonal matrix, and its diagonal components contain array correction values ​​h_cal to correct for phase and amplitude deviations between transmitting and receiving antennas. [y] .

[0424] The virtual receiver array correlation vector h, corrected for inter-antenna misalignment. _after_cal (f b_cfar ,f s_cfar ) becomes containing N Tx A column vector of ×Na elements. Hereinafter, each element will be represented as h1(f b_cfar ,f s_cfar ), ..., h NTx×Na (f b_cfar ,f s_cfar ), used for instructions on direction estimation processing.

[0425]

[0426]

[0427] Direction estimation unit 214 uses a virtual receiver array correlation vector h that has been corrected for inter-antenna bias. _after_cal (f b_cfar ,f s_cfar The direction estimation unit 214 performs direction estimation in both the horizontal and vertical directions. For example, in the horizontal and vertical direction estimation, within a specified angle range, the direction estimation evaluation function value P(θ,Φ,f) can be changed. b_cfar ,f s_cfar The spatial distribution is calculated using the azimuth direction θ and elevation direction Φ in the calculation. For example, the direction estimation unit 214 extracts a predetermined number of the maximum peaks of the calculated spatial distribution in descending order, and outputs the azimuth direction and elevation direction of each maximum peak as an estimated value of the direction of arrival (e.g., positioning output).

[0428] Arrival direction estimation evaluation function value P(θ,Φ,f) b_cfar ,f s_cfar There are various methods depending on the direction of arrival estimation algorithm. For example, the estimation method using an array antenna disclosed in Non-Patent Document 4 can also be used.

[0429] For example, beamforming can be represented as shown in equation (35). Additionally, methods such as Capon and MUSIC can also be applied.

[0430] P(θ u φ v f b_cfar f s_cfar )=|a H (θ u φ v )h _after_cal (f b_cfar f s_cfar )| 2 (35)

[0431] Here, the superscript H is the Hermitian transpose operator.

[0432] Additionally, the direction θ u This is the value that varies within the azimuth interval β1, within the azimuth range used for arrival direction estimation. For example, θ can be set as follows: u .

[0433] θ u =θ min +u×β1, u=0、…、NU-1

[0434] NU = floor[(θ max -θ min ) / β1]

[0435] Here, floor(x) is a function that returns the largest integer value that does not exceed the real number x.

[0436] Additionally, direction Φ V This is a value that varies within the elevation angle range used for direction of arrival estimation, using an elevation angle interval β2. For example, Φ can be set as follows: V .

[0437] Φ V =Φ min +v×β2,v=0、…、NV-1

[0438] NV = floor[(Φ max -Φ min ) / β2]

[0439] Furthermore, in this embodiment, the radar device 10 can also be configured with VA#1, ..., VA#(N) based on a virtual receiving array. Tx ×Na) and pre-calculate the direction vector a(θ) u ,θ v Here, the direction vector a(θ) u ,θ v ) is a virtual receiving array antenna whose complex response is based on the radar reflected wave arriving from the azimuth direction θ and the elevation direction Φ. Tx A column vector of order ×Na. The complex response a(θ) of the virtual receiver array antenna. u ,θ v ) represents the element spacing of the virtual receiving array antenna, calculated using geometric optics, assuming the radar reflected wave arrives from the azimuth direction θ and the elevation direction Φ.

[0440] Next, an example of the directional estimation result (computer simulation result) when the antenna configuration of the above configuration example 1 is applied will be described.

[0441] <Example 1 of the orientation estimation results in Example 1>

[0442] In Example 1, the direction estimation result is shown when the radar device 10 receives a reflected wave from a target.

[0443] Figure 16 (a) indicates the use of the MIMO antenna configuration of Configuration Example 1 (e.g., Figure 15 In case (a), the direction estimation unit 214 uses beamforming as an example of the direction estimation result (computer simulation result) when performing the direction of arrival estimation algorithm. Additionally, as a comparative example, Figure 16 (b) indicates that the use of Figure 1An example of the directional estimation results for the antenna configuration shown in (a).

[0444] Figure 16 (a) and Figure 16 (b) indicates, for example, in a MIMO antenna configuration, D H =0.5λ,D V An example of the direction estimation result when λ = 0.5.

[0445] in addition, Figure 16 (a) and Figure 16 (b) represents the following example, which plots the output of the arrival direction estimation evaluation function value within the range of ±90 degrees in the horizontal direction and ±90 degrees in the vertical direction, with the target truth value set to 0 degrees in the horizontal direction and 0 degrees in the vertical direction.

[0446] according to Figure 16 The direction estimation result shown in (a) obtains the maximum peak value at the target true value (0 degrees horizontally and 0 degrees vertically in this case), thus confirming that the direction estimation unit 214 has correctly estimated the target direction.

[0447] In addition, Figure 16 In configuration example 1 shown in (a), the horizontal 3dB beamwidth is approximately 16 degrees. Figure 16 In the comparative example shown in (b), the 3dB beamwidth in the horizontal direction is approximately 26 degrees. In configuration example 1 ( Figure 15 In the antenna configuration of (a)), the virtual antenna in the horizontal direction is represented by D. H The number of virtual antennas arranged at 0.5λ intervals is NV. H =6, while in the comparative example ( Figure 1 In the antenna configuration of (a)), the virtual antenna in the horizontal direction is represented by D. H The number of virtual antennas arranged at 0.5λ intervals is NV. H =4. Therefore, compared to the comparative example, the aperture length of the virtual antenna in the horizontal direction in Configuration Example 1 is more than 1.7 times. Thus, if... Figure 16 (a) and Figure 16 As shown in (b), in Configuration Example 1, the horizontal beamwidth is narrower compared to the Comparative Example.

[0448] In addition, Figure 16 In configuration example 1 shown in (a), the 3dB beamwidth in the vertical direction is approximately 29 degrees. Figure 16 In the comparative example shown in (b), the 3dB beamwidth in the vertical direction is approximately 26 degrees. For example, in configuration example 1 ( Figure 15 In the antenna configuration of (a)), the virtual antenna in the vertical direction is represented by D VThe number of virtual antennas arranged at 0.5λ intervals is NV. V =4, in the comparative example ( Figure 1 In the antenna configuration of (a)), the virtual antenna in the vertical direction is represented by D V The number of virtual antennas arranged at 0.5λ intervals is NV. V =4. Therefore, the aperture length of the virtual antenna in the vertical direction is the same in both Configuration Example 1 and Comparative Example, and thus, the beamwidth in the vertical direction is the same.

[0449] <Example 2 of the orientation estimation results from Example 1>

[0450] Example 2 shows the direction estimation result when radar device 10 receives reflected waves from two targets.

[0451] Figure 17 (a) indicates the use of the MIMO antenna configuration of Configuration Example 1 (e.g., Figure 15 In case (a), the direction estimation unit 214 uses beamforming as an example of the direction estimation result (computer simulation result) when the direction of arrival estimation algorithm is used.

[0452] In addition, as a comparative example, Figure 17 (b) indicates that the use of Figure 18 An example of the directional estimation results for the antenna configuration shown in (a). Figure 18 The antenna configuration shown in (a) is, for example, from Figure 15 The antenna configuration in (a) is the one in which Rx#4 (in other words, the antenna improves separation performance) is removed. Figure 18 (b) indicates according to Figure 18 Example of a virtual receiving antenna configuration obtained by the antenna configuration of (a).

[0453] in addition, Figure 17 (a) and Figure 17 (b) indicates, for example, in a MIMO antenna configuration, D H =0.5λ, D V An example of the direction estimation result when λ = 0.5.

[0454] in addition, Figure 17 (a) and Figure 17 (b) represents the following example, which plots the output of the arrival direction estimation evaluation function value within the range of ±90 degrees in the horizontal direction and ±90 degrees in the vertical direction when the truth value of target #1 is set to 25 degrees in the horizontal direction and 25 degrees in the vertical direction, and the truth value of target #2 is set to -25 degrees in the horizontal direction and -25 degrees in the vertical direction.

[0455] according to Figure 17 The direction estimation results shown in (a) show that the maximum peak value is obtained in the direction of the two target true values. Therefore, it can be confirmed that the direction estimation unit 214 has correctly estimated the target direction.

[0456] On the other hand, according to Figure 17 The direction estimation result shown in (b) shows that the peak value points towards the true values ​​of the two targets, but high-level sidelobes are also generated in directions different from the target directions. Therefore, in the comparative example, when there is a difference in received power between the reflected waves from the two targets, the received power in the sidelobe direction of the target with stronger received power may be higher than the peak level of the target with weaker received power, and the radar device may misjudge the direction estimation of the target with weaker received power. Thus, for Figure 18 The antenna configuration shown in (a) (transmit "L" shape, receive "L" shape) sometimes exhibits increased sidelobe levels in the presence of multiple targets. The following are some of the main reasons for this.

[0457] <Regarding vertical configuration>

[0458] • For a virtual receiving antenna, when the virtual antenna is configured in a vertical position—in other words, when there is a virtual antenna positioned on the vertical axis in the horizontal direction—it is difficult to separate multiple waves in the horizontal direction (e.g., Figure 18 (b) shows VA#12).

[0459] • For virtual receiving antennas, when multiple virtual antennas are configured in the vertical position, it is possible to separate multiple waves in the horizontal direction. However, when the horizontal spacing between the virtual antennas is more than one wavelength (e.g., Figure 18 As shown in (b) (VA#3, VA#6, VA#9), it is difficult to separate multiple waves with a specific horizontal spacing (azimuth spacing that produces grating lobes). In other words, at positions on the vertical axis with multiple virtual antennas in the horizontal direction, it is possible to separate multiple waves in the horizontal direction, but when the horizontal spacing between each virtual antenna is more than one wavelength, it is difficult to separate multiple waves with a specific horizontal spacing.

[0460] <Regarding horizontal configuration>

[0461] • For a virtual receiving antenna, when a virtual antenna is configured in a horizontal position—in other words, when a virtual antenna is configured in the vertical direction on the horizontal axis—it is difficult to separate multiple waves in the vertical direction (e.g., Figure 18 (b) shows VA#4 and VA#7.

[0462] • For virtual receiving antennas, when there are multiple virtual antennas in the horizontal position, it is possible to separate multiple waves in the vertical direction, but when the spacing in the vertical position is more than one wavelength (e.g., Figure 18 As shown in (b), VA#1 and VA#10 are difficult to separate multiple waves with a specific vertical spacing (elevation angle spacing that produces grating lobes). In other words, while multiple virtual antennas can be positioned on the horizontal axis in the vertical direction, it is difficult to separate multiple waves with a specific vertical spacing when the vertical spacing between the virtual antennas is more than one wavelength.

[0463] In contrast, in configuration example 1, as described above, the configuration for transmitting an "L" shape and receiving an "L" shape (e.g.) Figure 18 The antenna configuration shown in (a) is modified by adding an antenna based on either condition 1 or condition 2, thereby providing antenna coverage in at least one direction, both vertical and horizontal.

[0464] • For virtual receiving antennas, the configuration where the vertical (or horizontal) position does not include a single virtual antenna can be configured with multiple virtual antennas to separate multiple waves in the horizontal (or vertical) direction.

[0465] • For virtual receiving antennas, in the case of multiple virtual antennas in the vertical (or horizontal) position, the horizontal (or vertical) spacing can be reduced to a configuration of more than one wavelength to separate multiple waves at a specific horizontal (or vertical) spacing.

[0466] Thus, in configuration example 1 ( Figure 15 In (a)), relative to the comparative example ( Figure 18 (a) is based on condition 1, and an additional antenna Rx#4 is added. Thus, for example, it can be achieved through... Figure 15 (b) shows VA#16 (corresponding to Figure 15 (a) The virtual antenna of Rx#4 will be configured with a vertical position of a virtual antenna ( Figure 18 The vertical position of VA#12 in (a) is changed to the vertical position of multiple virtual antennas configured in the horizontal direction (e.g., Figure 15 (b) VA#15, VA#16), thereby separating multiple waves in the horizontal direction.

[0467] Additionally, for example, through Figure 15 As shown in (b), VA#4, VA#8, and VA#12 (corresponding to the virtual antennas of Rx#4) are positioned vertically to include these virtual antennas, such that the horizontal antenna spacing reaches the basic spacing D. HThe virtual antennas are configured in a manner that allows for the reduction of sidelobe levels in Configuration Example 1 compared to the Comparative Example.

[0468] Additionally, for example, through Figure 15 As shown in (b), VA#4 and VA#8 (corresponding to the virtual antennas of Rx#4) are positioned at various horizontal locations containing these virtual antennas so that the antenna spacing in the vertical direction reaches the basic spacing D. V The virtual antennas are configured in a manner that allows for the reduction of sidelobe levels in Configuration Example 1 compared to the Comparative Example.

[0469] Additionally, for example, it can be achieved through Figure 15 (b) shows VA#4 (corresponding to Figure 15 (a) The virtual antenna of Rx#4 will be configured with a horizontal position of a virtual antenna. Figure 18 (a) The horizontal position of VA#4 is changed to the horizontal position of multiple virtual antennas configured in the vertical direction (e.g., Figure 15 (b) VA#4, VA#5), thereby separating multiple waves in the vertical direction.

[0470] Additionally, for example, it can be achieved through Figure 15 (b) shows VA#8 (corresponding to Figure 15 (a) The virtual antenna of Rx#4 will be configured with a horizontal position of a virtual antenna. Figure 18 (a) The horizontal position of VA#7 is changed to the horizontal position of multiple virtual antennas configured in the vertical direction (e.g., Figure 15 (b) VA#8, VA#9), thereby separating multiple waves in the vertical direction.

[0471] The above illustrates an example of the orientation estimation result (computer simulation result) of Configuration Example 1.

[0472] The direction estimation unit 214 can, for example, output the direction estimation result and further output a value based on the distance index f. b_cfar Distance information (e.g., information obtained by transformation based on equation (8)), and target-based Doppler frequency index f b_cfar and the determination result DR of the folding determination unit 212 min The Doppler velocity information of the target is used as the positioning result. The direction estimation unit 214 may output the positioning result to the vehicle control device in the vehicle-mounted radar (not shown), or to the infrastructure control device in the infrastructure radar.

[0473] The direction estimation unit 214 can also, for example, be based on the Doppler frequency index f s_cfar and the determination result of the folding determination unit 212, that is, DR min , and calculate the Doppler frequency index f according to Equation (36) es_cfar . The Doppler frequency index f es_cfar is, for example, equivalent to the Doppler index when the FFT size of the Doppler analysis unit 210 is expanded to Loc × Ncode. Hereinafter, f es_cfar will be referred to as the "expanded Doppler frequency index".

[0474] f es_cfar = f s_cfar + DR min × Ncode (36)

[0475] In addition, it is assumed that up to the Doppler range of ±1 / (2 × Tr), the range of the expanded Doppler frequency index f es_cfar corresponding to this Doppler range is -Loc × Ncode / 2 ≤ f es_cfar < Loc × Ncode / 2. Therefore, when the calculation result of Equation (36) is f es_cfar < -Loc × Ncode / 2, f es_cfar + Loc × Ncode is set as f es_cfar . In addition, when f es_cfar ≥ Loc × Ncode / 2, f es_cfar - Loc × Ncode is set as f es_cfar .

[0476] In addition, the Doppler frequency information can also be converted into a relative velocity component and output. When converting the Doppler frequency index f es_cfar into the relative velocity component v d (f es_cfar ), the conversion can also be performed using Equation (37). Here, λ is the wavelength of the carrier frequency of the RF (Radio Frequency) signal output from the wireless transmission unit (not shown). When using a chirp signal as the radar transmission signal, λ is the wavelength of the center frequency of the frequency sweep band of the chirp signal. In addition, Δ f is the Doppler frequency interval in the FFT processing of the Doppler analysis unit 210. For example, in the present embodiment, Δ f = 1 / {Loc × N code × T r}.

[0477]

[0478] The operation example of the radar device 10 has been described above.

[0479] As described above, in Configuration Example 1, for the configuration of the multiple transmitting antennas 106 and multiple receiving antennas 202 of the radar device 10, according to the antenna configuration of Condition 1, Condition 1a, Condition 2 or Condition 2a, for example, it is possible to expand the aperture length of the virtual antenna using fewer antennas, thereby maintaining the angular measurement accuracy in at least one of the vertical and horizontal directions, and improving the separation performance of multiple waves.

[0480] Based on the above, this embodiment can improve the target detection accuracy of the radar device 10.

[0481] Furthermore, in Configuration Example 1, by increasing at least one of the number of transmit antennas and the number of receive antennas, it becomes the structure shown in Configuration Example 1 (e.g., Figure 15 The relationship between the virtual receiving antenna and the configuration shown in equation (31) is further increased by (a) in addition to (b). In other words, it becomes the relationship between the virtual receiving antenna and the configuration shown in equation (31). Figure 15 The virtual receiving antenna configuration shown in (b) further adds the configuration of other virtual receiving antennas. Therefore, the effects described in this embodiment are maintained, so even if the antenna configuration includes configuration example 1, the same effect can be obtained. Furthermore, the same applies to the following configuration examples.

[0482] <Configuration Example 2>

[0483] Figure 19 This is a diagram illustrating a configuration example (e.g., a MIMO antenna configuration example) of the transmitting antenna 106 (e.g., referred to as "Tx") and the receiving antenna 202 (e.g., referred to as "Rx") in Configuration Example 2.

[0484] exist Figure 19 In the example shown, the number of transmitting antennas N Tx There are 6 antennas (e.g., Tx#1, Tx#2, ..., Tx#6), and the number of receiving antennas Na is 8 (e.g., Rx#1, Rx#2, ..., Rx#8).

[0485] in addition, Figure 20 It means according to Figure 19 A diagram showing an example of a virtual receiving antenna configuration obtained by the antenna configuration shown.

[0486] For example, Figure 19 The antenna configuration is as follows: the number of antennas arranged horizontally is greater than the number of antennas arranged vertically, whether transmitting or receiving (e.g., Nt). H >Nt V And Nr H >Nr V Based on this configuration, in Figure 20In the virtual receiving antenna configuration shown, the number of antennas arranged in the horizontal direction is greater than the number of antennas arranged in the vertical direction. Compared with the aperture length in the vertical direction, the aperture length in the horizontal direction can be increased. Therefore, compared with the vertical direction, the radar device 10 can improve the angular resolution in the horizontal direction.

[0487] Here, the configuration of the virtual receiving array antenna can be represented, for example, based on the location of the transmitting antenna 106 constituting the transmitting array antenna (e.g., the location of the power supply point) and the location of the receiving antenna 202 constituting the receiving array antenna (e.g., the location of the power supply point), in the manner of Equation (31).

[0488] Additionally, the position coordinates of the transmitting antenna 106 (e.g., Tx#n) constituting the transmitting array antenna are described as "(X T_#n ,Y T_#n (For example, n = 1, ..., N) Tx The position coordinates of the receiving antenna 202 (e.g., Rx#m) constituting the receiving array antenna are described as "(X R_#m ,Y R_#m (e.g., m = 1, ..., Na), the position coordinates of the virtual antenna VA#k that constitutes the virtual receiving array antenna are described as "(X V_#k ,Y V_#k (For example, k = 1, ..., N) Tx ×Na).

[0489] Additionally, in equation (31), for example, VA#1 is denoted as "the location reference (0, 0) of the virtual receiving array".

[0490] exist Figure 19 In this configuration, transmitting antennas Tx#1 to Tx#6 are arranged in an "L" shape. For example, Tx#1 to Tx#4 are arranged horizontally, and Tx#1, Tx#5, and Tx#6 are arranged vertically (e.g., equivalent to condition 1(1)). For example, the position coordinates relative to Tx#1 ( XT_#1 Y XT_#1 The position coordinates of Tx#2 to Tx#6 are respectively (X T_#2 ,Y T_#2 )=(X T_#1 +5D H ,Y T_#1 ), (X T_#3 ,Y T_#3 )=(X T_#1 +10D H ,Y T_#1 ), (X T_#4 ,Y T_#4 )=(X T_#1 +15DH ,Y T_#1 ), (X T_#5 ,Y T_#5 )=(X T_#1 ,Y T_#1 +3D V ), (X T_#6 ,Y T_#6 )=(X T_#1 ,Y T_#1 +6D V Here, the antenna spacing of the horizontally arranged transmitting antennas Tx#1 to Tx#4 is 4D longer than the aperture length of the horizontally arranged receiving antennas 202. H Larger intervals (e.g., equivalent to condition 1(3)). Additionally, in Figure 19 In the diagram, the antenna spacing of the vertically arranged transmitting antennas Tx#1, Tx#5, and Tx#6 is 2D longer than the aperture length of the vertically arranged receiving antenna 202. V Larger interval 3D V Configurations are possible, but not limited to them.

[0491] On the other hand, Figure 19 Of the receiving antennas Rx#1 to Rx#8 shown with Na=8, the seven (=Na-Nz) receiving antennas Rx#1 to Rx#7, excluding the antenna used to improve separation performance (i.e., antenna Rx#8 with Nz=1), are arranged in an "L" shape (e.g., equivalent to condition 1 (2)). The antenna spacing of the receiving antennas Rx#1 to Rx#5 arranged in the horizontal direction is the basic horizontal spacing D. H .

[0492] For example, Figure 19 The receiving antennas Rx#1 to Rx#7 shown are configured by rotating the "L" shape 90° to the left. Rx#1 to Rx#5 are arranged horizontally, and Rx#5 to Rx#7 are arranged vertically. For example, the position coordinates (X) relative to Rx#1... R_#1 ,Y R_#1 The position coordinates of Rx#2 to Rx#7 are respectively (X R_#2 ,Y R_#2 )=(X R_#1 +D H ,Y R_#1 ), (X R_#3 ,Y R_#3 )=(X R_#1 +2D H ,Y R_#1 ), (X R_#4 ,Y R_#4 )=(X R_#1+3D H ,Y R_#1 ), (X R_#5 ,Y R_#5 )=(X R_#1 +4D H ,Y R_#1 ), (X R_#6 ,Y R_#6 )=(X R_#1 +4D H ,Y R_#1 +D V ), (X R_#7 ,Y R_#7 )=(X R_#1 +4D H ,Y R_#1 +2D V ).

[0493] In addition, Figure 19 In this configuration, the receiving antenna Rx#8 (e.g., an antenna for improving separation performance) corresponding to Nz=1 is positioned on the vertical axis (Y) relative to the receiving antennas Rx#1 to Rx#5 arranged in the horizontal direction. R_#1 Positions on different vertical axes (Y) R_#1 +D V ), and the basic horizontal spacing D between the receiving antennas Rx#5 to Rx#7 arranged in the vertical direction. H The position (e.g., equivalent to condition 1(4)). That is, the position coordinates of Rx#8 (X R_#8 ,Y R_#8 )=(X R_#1 +5D H ,Y R_#1 +D V ).

[0494] Furthermore, the following situation is explained, namely, in Figure 19 In the antenna configuration shown, the Nz receiving antennas, i.e., Rx#8, which improve separation performance, are positioned on the vertical axis (Y) relative to the receiving antennas 202 arranged in the horizontal direction. R_#1 Positions on different vertical axes (Y) R_#1 +D V When the receiving antenna Rx#8 is positioned horizontally adjacent to the receiving antenna Rx#6, it is positioned on the opposite side of the horizontally arranged receiving antennas, i.e., the position coordinates (X) of Rx#8. R_#8 ,Y R_#8 )=(X R_#1 +5D H ,Y R_#1 +D V This is possible, but not limited to, the case where the receiving antenna Rx#8 can also be configured in (X).R_#8 ,Y R_#8 )=(X R_#1 +3D H ,Y R_#1 +D V ), (X R_#8 ,Y R_#8 )=(X R_#1 +3D H ,Y R_#1 +2D V ) or (X R_#8 ,Y R_#8 )=(X R_#1 +5D H ,Y R_#1 +2D V ).

[0495] so, Figure 19 The MIMO antenna configuration shown is one that satisfies the above (condition 1).

[0496] In addition, Figure 19 In the middle, the antenna spacing D of the transmitting antenna 106 arranged in the horizontal direction TH The number of antennas Nr arranged horizontally is set to be greater than the number of receiving antennas. H The value of (=5)-1 and the antenna spacing D RH =D H The product of D RH ×(Nr H -1)=4D H Based on this setting, the following is constituted: Figure 20 The number of virtual antennas Nv arranged horizontally in the virtual receiver array antenna shown is... H For Nt H ×Nr H Components (in) Figure 20 The above configuration consists of 20 elements: VA#1 to VA#5, VA#9 to VA#13, VA#17 to VA#21, and VA#25 to VA#29. In other words, based on the above configuration, virtual antennas VA#1 to VA#5, VA#9 to VA#13, VA#17 to VA#21, and VA#25 to VA#29 can be configured without repetition in a horizontally arranged configuration.

[0497] Additionally, for example, the antenna spacing D TH The number of antennas Nr arranged horizontally as receiving antenna 202 H (=5) and antenna spacing D RH =D H The product of D RH ×Nr H (=5D HThus, the Nt antennas arranged horizontally in the virtual receiving array antenna constitute the antenna. H ×Nr H The virtual antennas, consisting of 20 elements, are spaced at equal intervals D. RH =D H They are arranged in a straight line.

[0498] Similarly, in Figure 19 In the middle, the antenna spacing D of the transmitting antenna 106 arranged in the vertical direction TV The number of antennas Nr arranged vertically is set to be greater than that of the receiving antenna 202. V The value of (=3)-1 and the antenna spacing D RV =D V The product of D RV ×(Nr V -1)=2D V Based on this setting, the following is constituted: Figure 20 The number of virtual antennas Nv arranged vertically in the virtual receiver array antenna shown is... V For Nt V ×Nr V Components (in) Figure 20 The nine components are VA#5~VA#7, VA#37~VA#39, and VA#45~VA#47. In other words, based on the above settings, virtual antennas VA#5~VA#7, VA#37~VA#39, and VA#45~VA#47 arranged vertically can be configured without repetition.

[0499] Additionally, for example, the antenna spacing D TV The number of antennas Nr arranged vertically as receiving antenna 202 V (=3) and antenna spacing D RV =D V The product of D RV ×Nr V (=3D V Thus, the Nt antennas arranged vertically in the virtual receiving array antenna constitute the antenna. V ×Nr V The virtual antennas, consisting of (=9) elements, are spaced at equal intervals D RV =D V They are arranged in a straight line.

[0500] Here, D H D V These are the basic intervals in the horizontal and vertical directions, respectively, and are specified intervals shorter than the wavelength (λ) of the radar signal. For example, D H D VThese can be set to approximately 0.45λ to 0.8λ. Furthermore, λ represents the wavelength of the carrier frequency of the radar's transmitted signal. For example, when using a chirped signal as the radar's transmitted signal, λ is the wavelength of the center frequency of the chirped signal's frequency scan band.

[0501] Thus, in a virtual receiver array configuration consisting of MIMO antenna configurations satisfying condition 1 (for example, the same applies in the cases of conditions 1a, 2, and 2a), the product of the number of each element of the virtual receiver antenna arranged in the horizontal and vertical directions is Nv. H ×Nv V =Nt H ×Nr H ×Nt V ×Nr V Additionally, depending on the "L" shape (or "T" shape, "+" shape) configuration, the transmitting and receiving antennas are Nt respectively. H >1, Nt V >1, Nr H >1, Nr V >1. Therefore, the number of components in the virtual receiving antenna is greater than the product of the number of transmitting and receiving antennas, N. Tx ×Na (e.g., Nv) H ×Nv V >N Tx ×Na). Therefore, it is possible to improve the effect of increasing the number of components in the vertical direction and the number of components in the horizontal direction of the virtual receiving antenna.

[0502] Furthermore, for example, the fewer the number of antennas Nz used to improve separation performance, the greater the effect of increasing the number of vertical and horizontal components in the virtual receiving antenna. On the other hand, even when the number of antennas Nz used to improve separation performance increases, the effect of increasing the number of components can still be achieved. For example, with... Figure 19 Similarly, for N Tx =6, Na=8, even when the number of antennas Nz=4 is used to improve separation performance, because Nr is set to... H =3, Nr V =3, so Nt H ×Nr H ×Nt V ×Nr V =4×3×3×3=108, the number of virtual receiving antenna elements is set to be greater than the product of the number of transmitting and receiving antennas N. Tx ×Na (=48).

[0503] Next, an example of the directional estimation result (computer simulation result) when the antenna configuration of the above configuration example 2 is applied will be described.

[0504] Figure 21(a) and Figure 21 (b) indicates the use of the MIMO antenna configuration in Configuration Example 2 (e.g., Figure 19 In the case of ), the direction estimation unit 214 uses beamforming as an example of the direction estimation result (computer simulation result) when the direction of arrival estimation algorithm is used.

[0505] Figure 21 (a) and Figure 16 (b) indicates, for example, in a MIMO antenna configuration, D H =0.5λ, D V An example of the direction estimation result when λ = 0.5.

[0506] in addition, Figure 21 (a) represents the following example, which plots the output of the arrival direction estimation evaluation function values ​​within the horizontal ±90 degree range and the vertical ±90 degree range, with the target truth value set to 0 degrees horizontally and 0 degrees vertically. Additionally, Figure 21 (b) represents the following example, which plots the output of the direction of arrival estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range when two target reflected waves with equal received power are received (e.g., the target true values ​​(horizontal, vertical) are (25°, 25°) and (-25°, -25°)).

[0507] according to Figure 21 The direction estimation result shown in (a) obtains the maximum peak value at the target true value (0 degrees horizontally and 0 degrees vertically in this case), thus confirming that the direction estimation unit 214 has correctly estimated the target direction. Furthermore, in Figure 21 In (a), the 3dB beamwidth in the horizontal direction of the frontal direction is approximately 4.5 degrees, and the 3dB beamwidth in the vertical direction is approximately 11 degrees. The angular resolution in the horizontal direction is higher than that in the vertical direction.

[0508] In addition, according to Figure 21 The direction estimation results shown in (b) obtain peak values ​​in the directions of the target true value (25°, 25°) and (-25°, -25°), thus confirming that the direction estimation unit 214 has correctly estimated the target direction. Furthermore, in Figure 21 In (b), it can be confirmed that the peak level (sidelobe level) with a direction different from the true value direction has been suppressed to about -10dB.

[0509] The above illustrates an example of the orientation estimation results (computer simulation results) for Configuration Example 2.

[0510] As described above, the MIMO array in Configuration Example 2 is configured such that, for both transmit and receive antennas, the number of antennas arranged horizontally is greater than the number of antennas arranged vertically (e.g., Nt). H >Nt V And Nr H >Nr V According to this configuration, in the virtual receiving antenna configuration, the number of antennas arranged in the horizontal direction is set to be greater than the number of antennas arranged in the vertical direction, which increases the aperture length in the horizontal direction compared to the aperture length in the vertical direction. The angular resolution in each direction is increased proportionally to the aperture length in the horizontal or vertical direction; therefore, the angular resolution in the horizontal direction can be improved compared to the angular resolution in the vertical direction.

[0511] The MIMO array configuration in Example 2, for instance, places greater emphasis on expanding the virtual antenna aperture in the horizontal direction than in the vertical direction. Therefore, it is more suitable for applications such as automotive radar where the horizontal viewing angle is larger than the vertical viewing angle. For example, in automotive radar applications where the horizontal viewing angle is larger than the vertical viewing angle, the probability of multiple waves arriving at different horizontal viewing angles is high. Therefore, with an antenna configuration like that in Example 2, which has higher resolution in the horizontal direction, target detection performance can be improved (in other words, missed detections can be reduced).

[0512] In addition, for example, in applications such as vehicle-mounted radar where horizontal angle resolution is more important than vertical angle resolution, vertical angle resolution is rarely required, so the vertical aperture length only needs to be sufficient to ensure estimation accuracy.

[0513] In addition, a higher angular resolution in the horizontal direction can reduce, for example, the probability that multiple waves arriving from the same horizontal direction cannot be separated in the horizontal direction, resulting in missed detection of targets due to decreased resolution in the vertical direction.

[0514] Alternatively, for example, when using the MIMO array configuration of Configuration Example 2, the direction estimation unit 214 can also use virtual receiving antennas arranged in the horizontal direction (in other words, not using virtual receiving antennas arranged in the vertical direction) to perform direction of arrival estimation in the horizontal dimension, and apply one-dimensional direction of arrival estimation processing in the vertical direction to the detected horizontal direction. In this case, because there are many virtual receiving antennas arranged in the horizontal direction, the following effect can be obtained: after suppressing the degradation of the reception quality (e.g., SNR: Signal to Noise Ratio) during one-dimensional direction of arrival estimation in the horizontal direction, the computational load of the direction estimation processing can be reduced.

[0515] (Variation 1 of Configuration Example 2)

[0516] In the MIMO array configuration of Configuration Example 2 (e.g., Figure 19 Although it is stated in the document that the spacing of the antennas (Rx#5, Rx#6, Rx#7) arranged in the vertical direction in the receiving antenna 202 is set to the basic spacing Dv in the vertical direction, the spacing of the antennas arranged in the vertical direction is not limited to this.

[0517] Figure 22 This is a diagram illustrating a configuration example (e.g., a MIMO antenna configuration example) of the transmitting antenna 106 (e.g., denoted as "Tx") and the receiving antenna 202 (e.g., denoted as "Rx") of a variation of configuration example 2. Figure 22 In the example shown, with Figure 19 Similarly, the number of transmitting antennas N Tx There are 6 receiving antennas (e.g., Tx#1, Tx#2, ..., Tx#6), and the number of receiving antennas Na is 8 (e.g., Rx#1, Rx#2, ..., Rx#8). Additionally, Figure 23 It means according to Figure 22 A diagram showing an example of a virtual receiving antenna configuration obtained by the antenna configuration shown.

[0518] For example, such as Figure 22 As shown, it can also be configured as follows, where the difference between the spacing 3Dv of the vertically arranged antennas (Tx#1, Tx#5, Tx#6) in the transmitting antenna 106 and the spacing 2Dv of the vertically arranged antennas (Rx#5, Rx#6, Rx#7) in the receiving antenna 202 is set to a basic vertical spacing Dv (=|3Dv-2Dv|). In this case, Figure 23 In the virtual receiving antenna shown, although the antennas arranged vertically (VA#5~VA#7, VA#37~VA#39, VA#45~VA#47) are spaced unequally, the inclusion of the fundamental vertical spacing Dv allows for suppression of vertical grating lobes. Furthermore, for example, with... Figure 20 compared to, Figure 23 The virtual receiving antenna shown can increase the size of the antenna element in the vertical direction and expand the aperture length in the vertical direction, thus improving the angular resolution in the vertical direction.

[0519] In addition, Figure 22While the antenna configuration describes a situation where the spacing (3Dv) of the vertically arranged transmitting antennas (Tx#1, Tx#5, Tx#6) and the spacing (2Dv) of the vertically arranged receiving antennas (Rx#5, Rx#6, Rx#7) are set to be equal, this is not a limitation; unequal spacing may also be used. In this case, for example, it is acceptable as long as the difference between at least one of the spacings of the vertically arranged transmitting antennas and the spacing of the vertically arranged receiving antennas is set to the basic vertical spacing Dv.

[0520] In addition, Figure 22 Although the example describes the application of condition 1, conditions 1a, 2, or 2a can also be applied. For example, the configuration for applying condition 1a can also be configured such that the difference between the spacing of the transmitting antennas arranged in the vertical direction and the spacing of the receiving antennas arranged in the vertical direction is set to the basic vertical spacing Dv. Similarly, the configuration for applying condition 2 or 2a can also be configured such that the difference between the spacing of the transmitting antennas arranged in the horizontal direction and the spacing of the receiving antennas arranged in the horizontal direction is set to the basic horizontal spacing D. H .

[0521] (Version 2 of Configuration Example 2)

[0522] In the MIMO array configuration of Configuration Example 2 (e.g., Figure 19 Although it is explained in the document that the spacing of the horizontally arranged antennas (e.g., Tx#1 to Tx#4) of the transmitting antenna 106 is set to be the aperture length of the horizontally arranged antennas (e.g., Rx#1 to Rx#5) of the receiving antenna 202 plus D H The resulting interval (e.g., in) Figure 19 In the case of 5D H However, the spacing between transmitting antennas arranged in the horizontal direction is not limited to this, and can also be larger.

[0523] In other words, although it was explained that... Figure 20 The virtual receiving antennas shown are arranged horizontally with a basic horizontal spacing D. H This can be done in the case of equally spaced configurations, but it is not limited to this.

[0524] Figure 24 This is a diagram illustrating a configuration example (e.g., a MIMO antenna configuration example) of the transmitting antenna 106 (e.g., denoted as "Tx") and the receiving antenna 202 (e.g., denoted as "Rx") of a variation 2 of configuration example 2. Figure 24 In the example shown, with Figure 19 Similarly, the number of transmitting antennas NTx There are 6 receiving antennas (e.g., Tx#1, Tx#2, ..., Tx#6), and the number of receiving antennas Na is 8 (e.g., Rx#1, Rx#2, ..., Rx#8). Additionally, Figure 25 It means according to Figure 24 A diagram showing an example of a virtual receiving antenna configuration obtained by the antenna configuration shown.

[0525] For example, such as Figure 24 As shown, the spacing of the horizontally arranged antennas (Tx#1 to Tx#4) of the transmitting antenna 106 can also be set to the aperture length 4D of the horizontally arranged antennas (Rx#1 to Rx#5) of the receiving antenna 202. H Add 2D H The resulting interval (6D) H In this case, Figure 25 The virtual receiving antennas shown are arranged horizontally with varying spacing (e.g., VA#1~VA#5, VA#9~VA#13, VA#17~VA#21, VA#25~VA#29), but because the horizontal aperture length of the virtual receiving antenna is increased, the horizontal resolution can be further improved.

[0526] Figure 26 This is a diagram illustrating other configuration examples (e.g., MIMO antenna configuration examples) of the transmitting antenna 106 (e.g., denoted as "Tx") and receiving antenna 202 (e.g., denoted as "Rx") of configuration example 2, variant 2. Figure 26 In the example shown, with Figure 19 Similarly, the number of transmitting antennas N Tx There are 6 receiving antennas (e.g., Tx#1, Tx#2, ..., Tx#6), and the number of receiving antennas Na is 8 (e.g., Rx#1, Rx#2, ..., Rx#8). Additionally, Figure 27 It means according to Figure 26 A diagram showing an example of a virtual receiving antenna configuration obtained by the antenna configuration shown.

[0527] like Figure 26 As shown, the spacing of the horizontally arranged antennas (Tx#1 to Tx#4) of the transmitting antenna 106 can also be set to the aperture length 4D of the horizontally arranged antennas (Rx#1 to Rx#5) of the receiving antenna 202. H Uneven addition of a value greater than D H The interval obtained from the interval. In Figure 26 In the example, the interval between Tx#1 and Tx#2 is set to 6D. H The interval between Tx#2 and Tx#3 is set to 7D. H The interval between Tx#3 and Tx#4 is set to 6D.H .

[0528] In this way, by setting unevenly... Figure 26 The spacing between the horizontally arranged transmitting antennas (Tx#1~Tx#4) in the diagram. Figure 27 The non-uniformity of the horizontally arranged antennas (e.g., VA#1~VA#5, VA#9~VA#13, VA#17~VA#21, VA#25~VA#29) of the virtual receiving antenna is further increased. Therefore, the sidelobes when estimating the direction of arrival can be further reduced. In addition, because the horizontal aperture length of the virtual receiving antenna is further increased, the horizontal resolution can be further improved.

[0529] In addition, Figure 24 and Figure 26 Although the example describes the application of condition 1, conditions 1a, 2, or 2a can also be applied. For example, in the configuration applying condition 1a, the spacing of the horizontally arranged receiving antennas can also be set to the sum of the aperture length of the horizontally arranged transmitting antennas and the basic horizontal spacing D. H The resulting spacing is larger and more uneven. Similarly, in the configuration of application condition 2, the spacing of the transmitting antennas arranged in the vertical direction can also be set to be the sum of the aperture length of the receiving antennas arranged in the vertical direction and the basic vertical spacing D. V The resulting spacing is larger and more uneven. Similarly, in the configuration of application condition 2a, the spacing of the receiving antennas arranged in the vertical direction can also be set to be the sum of the aperture length of the transmitting antennas arranged in the vertical direction and the basic vertical spacing D. V The resulting intervals are larger and more uneven.

[0530] The above explains variation 2 of configuration example 2.

[0531] The above describes one embodiment of this disclosure.

[0532] Furthermore, the configuration that satisfies condition 1 above can be further modified as described below (hereinafter referred to as "the modified configuration of condition 1").

[0533] (A variation of condition 1)

[0534] For example, in condition 1, the multiple antennas (e.g., corresponding to the second antenna) of the (Na-Nz) receiving antennas 202 arranged at different positions in the vertical direction are not limited to the case where they are arranged in a straight line in the vertical direction.

[0535] For example, in the receiving antenna 202 configured to satisfy condition 1, there is an antenna for improving separation performance, and antennas spaced at a basic interval D in the horizontal direction. H The configuration of the antenna adjacent to the separation performance enhancement antenna can also be such that its horizontal position differs from the horizontal positions of the other receiving antennas. In other words, the separation performance enhancement antenna, and the antenna in the vertical direction that has the same vertical position as the separation performance enhancement antenna among a plurality of receiving antennas arranged in the vertical direction, can also be configured in a horizontal position different from the horizontal position of the other receiving antennas arranged in the vertical direction.

[0536] For example, antennas that improve separation performance, and antennas with a basic spacing D in the horizontal direction. H The receiving antenna adjacent to the antenna used to improve separation performance can also be horizontally offset from the configuration that satisfies condition 1 by a basic horizontal spacing D. H Configured in integer multiples.

[0537] Figure 28 It means relative to Figure 22 The diagram shows an example of a modified configuration of antenna configuration that satisfies condition 1. Additionally, Figure 29 It means according to Figure 22 A diagram showing an example of a virtual receiving antenna configuration obtained by the antenna configuration shown.

[0538] like Figure 28 As shown, the separation performance is improved using antenna Rx#8, and the separation is achieved at a basic interval D in the horizontal direction. H The configuration of antenna Rx#6, adjacent to antenna Rx#8 for improved separation performance, is different in horizontal position from the other receiving antennas (Rx#1 to Rx#5, Rx#7). In other words, in Figure 28 In the middle, the horizontal positions of Rx#6 and Rx#8 can also be within the basic interval D. H Horizontal direction ( Figure 28 (to the right of the middle) and Figure 22 The configurations shown are set in a staggered manner.

[0539] According to a variation of condition 1, for example, an antenna configuration with a larger vertical dimension can be achieved. For example, a subarray consisting of multiple planar patch antennas arranged vertically can be applied to the antenna element. By using an antenna with a subarray structure, the directional gain of the antenna in the vertical direction can be improved, thereby improving the range detection performance of the radar device 10.

[0540] Additionally, for example, antennas that improve separation performance, and antennas with a basic spacing D in the horizontal direction. HEven if the horizontal position of the receiving antenna adjacent to the antenna used to improve separation performance is changed, the separation performance in the horizontal direction is not affected. Therefore, this modified configuration is appropriate.

[0541] The above explains the modified configuration of condition 1.

[0542] Similarly, the configuration that satisfies condition 1a above can be further implemented with the following modified configuration (hereinafter referred to as "modified configuration of condition 1a").

[0543] (A variation of condition 1a)

[0544] For example, in the transmitting antenna 106 configured to satisfy condition 1a, there is an antenna for improving separation performance, and an antenna spaced at a basic interval D in the horizontal direction. H The horizontal position of the antenna adjacent to the antenna used to improve separation performance can also be different from the horizontal position of other transmitting antennas.

[0545] For example, antennas that improve separation performance, and antennas with a basic spacing D in the horizontal direction. H The transmitting antenna adjacent to the antenna used to improve separation performance can also be horizontally offset from the basic horizontal spacing D of the configuration that satisfies condition 1a. H Configured in integer multiples.

[0546] According to a modified configuration of condition 1a, for example, an antenna configuration with a larger vertical dimension can be achieved. For example, a subarray consisting of multiple planar patch antennas arranged vertically can be applied to the antenna element. By using an antenna with a subarray structure, the directional gain of the antenna in the vertical direction can be improved, thereby improving the range detection performance of the radar device 10.

[0547] Additionally, for example, antennas that improve separation performance, and antennas with a basic spacing D in the horizontal direction. H Even if the horizontal position of the transmitting antenna adjacent to the antenna used to improve separation performance is changed, the separation performance in the horizontal direction will not be affected. Therefore, this modified configuration is suitable.

[0548] The above explains the modified configuration of condition 1a.

[0549] Furthermore, similarly to the variations of condition 1 and condition 1a, variations of condition 2 and condition 2a can also be applied.

[0550] Alternatively, in one embodiment of the MIMO array configuration disclosed herein, a configuration obtained by swapping the horizontal and vertical directions can also be used. The virtual receiver array configuration can obtain a configuration obtained by swapping the horizontal and vertical directions. Thus, the angular separation performance obtained by swapping the horizontal and vertical directions can be achieved.

[0551] Furthermore, the above embodiment describes a situation where, for example, the radar device 10 uses orthogonal codes not used for encoding multiplexed transmission to determine Doppler folding in the received signal (e.g., the output of the Doppler analysis unit 210 for each coded element of the encoded multiplexed signal). Through this Doppler folding determination, for example, the radar device 10 can determine folding within a Doppler range that is, for example, a multiple of the code length of the orthogonal code sequence, compared to the Doppler analysis range in the Doppler analysis unit 210. Therefore, according to this embodiment, the radar device 10 can expand the Doppler range that can be detected unambiguously to the same Doppler range as when transmitting with a single antenna.

[0552] Furthermore, when performing code separation based on the determination result of Doppler folding, for example, the radar device 10 can suppress the mutual interference between the coded multiplexed signals to the level of noise by performing Doppler phase correction including folding. Therefore, it can suppress the degradation of radar detection performance and perform coded multiplexing transmission of MIMO radar.

[0553] Furthermore, the radar device 10 may not use the coding multiplexing method described above, or it may use other multiplexing methods. Additionally, the radar device 10 may not perform the Doppler folding determination described above. For example, the coding generation unit 104 may also make the N contained in the coding sequence of code length Loc... allcode The number of code multiplexing in an orthogonal code N CM and orthogonal code number N allcode Equal. The phase rotation unit 105 can also use the N contained in the coding sequence of code length Loc. allcode All orthogonal codes are encoded and multiplexed. Furthermore, in this case, since the folded determination unit 212 of the radar device 10 is not used, the Doppler frequency range becomes ±1 / (2Loc×Tr).

[0554] Furthermore, the number of antennas in a MIMO antenna (e.g., the number of transmit antennas and the number of receive antennas) is not limited to the number of antennas shown in the examples of the antenna configurations described above. For example, a MIMO antenna may also be a structure that includes the antenna configuration in at least one of the antenna configuration examples described above. A MIMO antenna may also be a structure that includes an antenna configuration that satisfies at least one of the conditions 1, 1a, 2, and 2a described above. In other words, the radar device 10 may include antennas not shown, in addition to the antennas shown in the illustrated antenna configuration examples.

[0555] In one embodiment of the radar apparatus of this disclosure, the radar transmitting unit and the radar receiving unit may also be independently configured in physically separate locations. Furthermore, in one embodiment of the radar receiving unit of this disclosure, the direction estimation unit and other constituent units may also be independently configured in physically separate locations.

[0556] Although not illustrated, a radar device according to one embodiment of this disclosure includes, for example, a CPU (Central Processing Unit), a recording medium such as ROM (Read Only Memory) storing a control program, and an operating memory such as RAM (Random Access Memory). In this case, the functions of each of the above components are implemented by the CPU executing the control program. However, the hardware structure of the radar device is not limited to this example. For example, each functional unit of the radar device can also be implemented as an integrated circuit (IC). Each functional unit can be implemented independently on a single chip, or it can be implemented as a single chip including some or all of it.

[0557] Various embodiments have been described above with reference to the accompanying drawings, but this disclosure is not limited to these examples. Various modifications and alterations will be readily apparent to those skilled in the art within the scope of the claims, and these modifications and alterations should be understood to fall within the technical scope of this disclosure. Furthermore, the constituent elements of the above embodiments can be combined arbitrarily without departing from the spirit of the invention.

[0558] In addition, the term "part" in the above embodiments can be replaced by other terms such as "...circuitry", "...assembly", "device", "unit" or "module".

[0559] In the above embodiments, examples of using hardware to constitute this disclosure have been described, but this disclosure can also be implemented by software with the cooperation of hardware.

[0560] Furthermore, the functional blocks used in the descriptions of the above embodiments are typically implemented as integrated circuits, i.e., LSIs (Large Scale Integration). Integrated circuits can also control the functional blocks used in the descriptions of the above embodiments and include input terminals and output terminals. These functional blocks can be monolithically implemented independently, or they can be monolithically implemented in a manner that includes some or all of them. Here it is referred to as "LSI," but depending on the level of integration, it can also be called "IC," "System LSI," "Very Large LSI," or "Extra Large LSI."

[0561] Furthermore, the method of integrating LSIs is not limited to LSIs; it can also be achieved using dedicated circuits or general-purpose processors. Alternatively, it can utilize FPGAs (Field Programmable Gate Arrays) that can be programmed after LSI fabrication, or reconfigurable processors that allow for reconfiguration of the connections or settings of the circuit blocks within the LSI.

[0562] Furthermore, if advancements in semiconductor technology or other derived technologies lead to the development of integrated circuit technologies that can replace LSIs, these technologies could certainly be used to integrate functional blocks. There are also possibilities for applications such as biotechnology.

[0563] <Summary of this public disclosure>

[0564] A radar device according to an embodiment of this disclosure includes: a transmitting circuit that uses a plurality of transmitting antennas to transmit a transmitting signal; and a receiving circuit that uses a plurality of receiving antennas to receive a reflected wave signal of the transmitted signal after reflection from an object. One of the plurality of transmitting antennas and the plurality of receiving antennas includes a plurality of first antennas disposed at different positions in a first direction, a plurality of second antennas disposed at different positions in a second direction orthogonal to the first direction, and a third antenna different from the first antennas and the second antennas. At least one of the plurality of first antennas overlaps with one of the plurality of second antennas. The third antenna is disposed at a position different from the arrangement of the plurality of first antennas in the second direction and separated from the arrangement of the plurality of second antennas by a predetermined interval in the first direction. At least one interval between the plurality of first antennas is the predetermined interval. The other of the plurality of transmitting antennas and the plurality of receiving antennas includes a plurality of fourth antennas disposed in the first direction and a plurality of fifth antennas disposed in the second direction. At least one of the plurality of fourth antennas overlaps with one of the plurality of fifth antennas. The interval between the plurality of fourth antennas in the first direction is greater than the aperture length of the plurality of first antennas.

[0565] In one embodiment of this disclosure, the aperture length in the first direction of the virtual receiving antenna, which is composed of the plurality of transmitting antennas and the plurality of receiving antennas, is greater than the aperture length in the second direction.

[0566] In one embodiment of this disclosure, in the first direction, the third antenna is configured on the side with more of the configured first antennas relative to the configuration positions of the plurality of second antennas.

[0567] In one embodiment of this disclosure, in the first direction, the third antenna is configured on the side with fewer of the configured first antennas relative to the configuration positions of the plurality of second antennas.

[0568] In one embodiment of this disclosure, the number of antennas in the first direction is greater than the number of antennas in the second direction in both the plurality of transmitting antennas and the plurality of receiving antennas.

[0569] In one embodiment of this disclosure, the difference between the spacing of the plurality of transmitting antennas and the spacing of the plurality of receiving antennas in at least one of the first direction and the second direction is a value of the predetermined interval.

[0570] In one embodiment of this disclosure, in at least one of the first direction and the second direction, the antenna spacing of one of the plurality of transmitting antennas and the plurality of receiving antennas is greater than the antenna aperture length of the other of the plurality of transmitting antennas and the plurality of receiving antennas.

[0571] In one embodiment of this disclosure, the first direction is a horizontal direction.

[0572] In one embodiment of this disclosure, the third antenna and the antennas of the plurality of second antennas whose positions in the second direction are the same as those of the third antenna are configured at positions different from those of the other antennas of the plurality of second antennas in the first direction.

[0573] In one embodiment of this disclosure, the antenna spacing in the first direction of at least one of the plurality of transmitting antennas and the plurality of receiving antennas is unequal.

[0574] In one embodiment of this disclosure, the plurality of transmitting antennas and the plurality of receiving antennas are respectively arranged in an "L" shape, a "T" shape, or a "+" shape.

[0575] In one embodiment of this disclosure, the value of the specified interval is a value in the range of 0.45 to 0.8 times the wavelength.

[0576] The above describes various implementation methods, but it should be understood that various changes in form or details may be made without departing from the spirit and scope of the invention as currently or hereafter claimed.

[0577] This application claims and enjoys the rights of Japanese Patent Application No. 2020-174017, filed on October 15, 2020, the disclosure of which in its specification, drawings and abstract is incorporated herein by reference.

[0578] Industrial applicability

[0579] This disclosure is suitable for use as a radar device for detecting wide-angle ranges.

Claims

1. A radar device, characterized in that, include: The transmitting circuit uses multiple transmitting antennas to transmit signals. as well as The receiving circuit uses multiple receiving antennas to receive the reflected wave signal of the transmitted signal after it has been reflected by an object. The antenna of one of the plurality of transmitting antennas and the plurality of receiving antennas includes a plurality of first antennas disposed at different positions in a first direction, a plurality of second antennas disposed at different positions in a second direction orthogonal to the first direction, and a third antenna different from the first antennas and the second antennas. One of the plurality of first antennas is a first repeating antenna that is repeated by one of the plurality of second antennas. The third antenna is positioned at a location different from the configuration positions of the plurality of first antennas in the second direction and separated from the configuration positions of the plurality of second antennas by a first predetermined interval in the first direction; or, the third antenna is positioned at a location different from the configuration positions of the plurality of second antennas in the first direction and separated from the configuration positions of the plurality of first antennas by a second predetermined interval in the second direction. At least one interval in the first direction between the plurality of first antennas is the first predetermined interval. At least one interval in the second direction between the plurality of second antennas is the second predetermined interval. When the value obtained by subtracting the number of antennas of the third antenna from the number of antennas of one of the plurality of transmitting antennas and the plurality of receiving antennas is 4, the number of antennas of the plurality of first antennas is different from the number of antennas of the plurality of second antennas. The antenna of the other of the plurality of transmitting antennas and the plurality of receiving antennas includes a plurality of fourth antennas configured in the first direction and a plurality of fifth antennas configured in the second direction. One of the second repeating antennas among the plurality of fourth antennas is a repeating antenna among the plurality of fifth antennas. When the number of antennas in one of the plurality of transmitting antennas and the plurality of receiving antennas is 4, the number of antennas in the plurality of fourth antennas is different from the number of antennas in the plurality of fifth antennas. The spacing between the plurality of fourth antennas in the first direction is greater than the aperture length of the plurality of first antennas.

2. The radar device as claimed in claim 1, wherein, The aperture length in the first direction of the virtual receiving antenna, which is composed of the plurality of transmitting antennas and the plurality of receiving antennas, is greater than the aperture length in the second direction.

3. The radar device as described in claim 1, wherein, In the first direction, the third antenna is positioned on the side with more of the configured first antennas relative to the configuration positions of the plurality of second antennas.

4. The radar device as claimed in claim 1, wherein, In the first direction, the third antenna is positioned on the side with fewer of the configured first antennas, relative to the configuration positions of the plurality of second antennas.

5. The radar device as claimed in claim 1, wherein, In both the plurality of transmitting antennas and the plurality of receiving antennas, the number of antennas in the first direction is greater than the number of antennas in the second direction.

6. The radar device as claimed in claim 5, wherein, In the first direction, the difference between the spacing of the plurality of first antennas and the spacing of the plurality of fourth antennas is the value of the first predetermined interval, or In the second direction, the difference between the spacing of the plurality of second antennas and the spacing of the plurality of fifth antennas is the value of the second predetermined interval.

7. The radar device as claimed in claim 5, wherein, In at least one of the first direction and the second direction, the antenna spacing of one of the plurality of transmitting antennas and the plurality of receiving antennas is greater than the antenna aperture length of the other of the plurality of transmitting antennas and the plurality of receiving antennas.

8. The radar device as claimed in claim 5, wherein, The first direction is the horizontal direction.

9. The radar device as claimed in claim 1, wherein, The third antenna and the antennas in the plurality of second antennas whose positions in the second direction are the same as those in the third antenna are configured at positions different from those of the other antennas in the plurality of second antennas in the first direction.

10. The radar device as claimed in claim 1, wherein, The antenna spacing in the first direction of at least one of the plurality of transmitting antennas and the plurality of receiving antennas is unequal.

11. The radar device as claimed in claim 1, wherein, The plurality of transmitting antennas and the plurality of receiving antennas are respectively arranged in an "L" shape, a "T" shape, or a "+" shape.

12. The radar device as claimed in claim 1, wherein, The values ​​of the first specified interval and the second specified interval are either within the range of 0.45 to 0.8 times the wavelength.

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