Radar device

Abstract

To provide a radar device capable of suppressing the reduction of a measurable relative speed range without lowering the detection accuracy of a target.SOLUTION: A radar device includes: a plurality of transmitting antennas and a plurality of receiving antennas; a transmission control section that causes one transmitting antenna of the plurality of transmitting antennas to transmit a signal continuously a present number of times, and switches the transmitting antenna for transmitting the signal when the set number of times of transmission of the signal is completed; and an azimuth estimation section that estimates a target azimuth in which a target is present. The azimuth estimation section estimates, on the basis of a reference azimuth estimated using an input signal corresponding to an array obtained by combining one transmitting antenna and the plurality of receiving antennas, a phase rotation amount of phase rotation of the input signal generated when the transmission control section switches the transmitting antenna, compensates the phase rotation of the input signal using the estimated phase rotation amount, and estimates the target azimuth on the basis of the input signal whose phase rotation is compensated.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a radar device for detecting a target. [Background technology]

[0002] Conventionally, radar devices using the MIMO (Multiple-Input and Multiple-Output) method are known (see, for example, Patent Documents 1 and 2). Such MIMO radar transmits signals multiplexed using time division, frequency division, or code division from multiple transmitting antennas, receives signals reflected by surrounding objects using multiple receiving antennas, and separates and receives the multiplexed transmitted signals from each received signal. Through this processing, the MIMO radar can extract a complex propagation path response expressed as the product of the number of transmitting antennas and the number of receiving antennas, and performs array signal processing on these received signals as a virtual receiving array.

[0003] In particular, Patent Document 1 discloses a MIMO radar that uses time division multiplexing transmission, which transmits signals by shifting the transmission time for each transmitting antenna (hereinafter referred to as "time division multiplexing MIMO radar"). The time division multiplexing MIMO radar disclosed in Patent Document 1 outputs a transmission signal while switching the transmitting antennas at a predetermined cycle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-304417 [Patent Document 2] Special Publication No. 2011-526371 Summary of the Invention [Problem to be solved by the invention]

[0005] The time-division multiplexing MIMO radar described in Patent Document 1 switches the transmitting antennas that transmit the transmission signals at a predetermined cycle, which may result in a longer time required to complete transmission of the transmission signals from all transmitting antennas compared to frequency-division transmission or code-division transmission. For this reason, for example, when transmitting transmission signals from each transmitting antenna and detecting the Doppler frequency from the received phase change, as in Patent Document 2, the time interval for observing the received phase change becomes longer when applying Fourier frequency analysis to detect the Doppler frequency. Therefore, the Doppler frequency range in which the Doppler frequency can be detected without aliasing (the range of relative velocities of the target that can be measured) is reduced.

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide a radar device that can suppress a reduction in the measurable range of relative velocities without reducing the target detection accuracy. [Means for solving the problem]

[0007] A radar device according to the present invention includes a plurality of transmitting antennas and a plurality of receiving antennas, a transmission control unit that causes one of the plurality of transmitting antennas to transmit a signal a preset number of times in succession and switches the transmitting antenna that transmits the signal when the set number of signal transmissions is completed, and an azimuth estimation unit that estimates a target azimuth in which a target exists, wherein the azimuth estimation unit estimates the amount of phase rotation of the input signal that occurs when the transmission control unit switches the transmitting antennas based on a reference azimuth estimated using an input signal corresponding to an array that combines one transmitting antenna and multiple receiving antennas, compensates for the phase rotation of the input signal using the estimated amount of phase rotation, and estimates the target azimuth based on the input signal with the phase rotation compensated. [Effects of the Invention]

[0008] According to the present invention, by continuously transmitting signals from one transmitting antenna, the transmission period from the same transmitting antenna can be shortened, thereby suppressing a reduction in the measurable relative velocity range. Furthermore, by estimating the amount of phase rotation based on a reference direction estimated using an input signal corresponding to an array that combines one transmitting antenna and multiple receiving antennas, it is possible to compensate for phase rotation that occurs when transmitting antennas are switched. Therefore, the radar device of the present invention can suppress a reduction in the measurable relative velocity range without reducing the target detection accuracy. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram showing a radar device according to a first embodiment. [Figure 2] FIG. 2 is a diagram for explaining a virtual receiving array configured by the radar device according to the first embodiment. [Figure 3] FIG. 2 is a diagram for explaining a method for controlling transmission timing according to the first embodiment. [Figure 4] 4 is a flowchart showing the overall processing flow of the radar device according to the first embodiment. [Figure 5] 4 is a flowchart showing a transmission control method of the radar device according to the first embodiment. [Figure 6] 4 is a flowchart showing a reception control method of the radar device according to the first embodiment. [Figure 7] 4 is a flowchart showing a reception control method of the radar device according to the first embodiment. [Figure 8] 4 is a flowchart showing a direction estimation method of the radar device 1 according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and various modifications are possible without departing from the spirit of the present invention. Furthermore, the present invention includes all possible combinations of the configurations shown in the following embodiments. In addition, in each drawing, components with the same reference numerals are the same or equivalent, and this is common throughout the entire specification.

[0011] Embodiment 1 FIG. 1 is a schematic diagram showing a radar device 1 according to a first embodiment. The radar device 1 is installed on a road, for example, and is used to detect targets such as vehicles present on the road. The target detection results by the radar device 1 are output to a control device 10 that is higher up the radar device 1. The target detection results are used to provide road traffic information such as information for merging assistance on expressways, for example. The radar device 1 uses an FMCW (Frequency Modulated Continuous Wave) system and a MIMO (Multiple-Input and Multiple-Output) system. The radar device 1 also implements MIMO by time division multiplexing. As shown in FIG. 1, the radar device 1 is configured to receive multiple (N t a transmitter 2 having a wireless transmission function (not shown), and a plurality of (N r The radar device 1 includes a receiving unit 3 having a wireless receiving function (not shown), and a signal processing device 4. The radar device 1 also includes N t 24 transmit antennas and N r and receiving antennas 31.

[0012] The transmitter 2 includes a signal generator 21, an oscillator 22, and a plurality of transmission selector switches (SW) 23. The signal generator 21 generates a modulated signal whose voltage changes in a sawtooth waveform and supplies it to the oscillator 22. The oscillator 22 generates a transmission signal, which is a chirp signal, based on the modulated signal generated by the signal generator 21 and outputs it to the transmission selector switch 23. The transmission selector switch 23 outputs the transmission signal to the transmission antenna 24 only when it is time for time division multiplexing transmission. The transmission selector switch 23 is set to an ON or OFF state. Each of the plurality of transmission selector switches 23 corresponds to one transmission antenna 24. When the transmission selector switch 23 is in the ON state, it outputs the transmission signal to the corresponding transmission antenna 24. When the transmission selector switch 23 is in the OFF state, it does not output the transmission signal to the corresponding transmission antenna 24. The transmitter 2 may also include a power amplifier for amplifying the transmission signal.

[0013] The transmitting antenna 24 receives a transmission signal from the corresponding transmission changeover switch 23 of the transmitter 2, converts the transmission signal into a transmission wave TxW, and outputs it. The transmission wave TxW is reflected by a target and becomes a reflected wave RxW, which enters the receiving antenna 31. The receiving antenna 31 outputs a reception signal obtained from the reflected wave RxW to the receiver 3.

[0014] The receiver 3 includes a plurality of low-noise amplifiers 32, a plurality of mixers 33, and a plurality of A / D converters (ADCs) 34. The low-noise amplifiers 32 amplify the received signals from the respective receiving antennas 31 and output the amplified signals to the mixers 33. The mixers 33 receive the received signals output from the low-noise amplifiers 32 and the transmitted signals from the oscillator 22 of the transmitter 2. The mixers 33 mix the transmitted signals and received signals. This generates beat signals having a beat frequency that is the difference between the frequency of the transmitted signals and the frequency of the received signals. The A / D converters 34 convert the generated beat signals into digital signals and output the digital signals to the signal processing device 4. Each of the plurality of low-noise amplifiers 32, the plurality of mixers 33, and the plurality of A / D converters 34 corresponds to one receiving antenna 31. The low-noise amplifiers 32, the mixers 33, and the A / D converters 34 process the received signals received from the corresponding receiving antennas 31.

[0015] The signal processing device 4 performs various processes such as controlling the transmission unit 2 and calculating the relative position of the target based on the beat signal. The signal processing device 4 is a microcomputer including a processor such as a CPU (Central Processing Unit) and a memory. The signal processing device 4 has a transmission control unit 5, a data processing unit 6, and a memory 7. The transmission control unit 5 and the data processing unit 6 are functional units realized by the processor reading and executing a program stored in the memory. The program is recorded as software, for example. The memory 7 also stores various data for the processor to perform calculations, calculation results, etc. The memory 7 is, for example, a RAM (Random Access Memory). The memory 7 is connected to the control device 10, and data can be input and referenced from the control device 10.

[0016] The signal processing device 4 may be a DSP (Digital Signal Processor) or an FPGA (Field Programmable Gate Array).Furthermore, each functional unit may be divided and arranged in a plurality of microcomputers, DSPs, FPGAs, etc.

[0017] The transmission control unit 5 controls the timing of transmission of the transmission signal by the transmitter 2, the switching of the transmission antenna 24 of the transmitter 2, and the generation of the modulated signal by the signal generation unit 21 of the transmitter 2. The switching of the transmission antenna 24 of the transmitter 2 is performed by turning on only the transmission changeover switch 23 that transmits the transmission wave among the multiple transmission changeover switches 23 and turning off the other transmission changeover switches 23.

[0018] The data processing unit 6 performs various processes based on the beat signal captured via the A / D converter 34. As described above, in the radar device 1, transmission signals multiplexed using time division are transmitted from the multiple transmission antennas 24 as transmission waves TxW, and reflected waves RxW reflected from surrounding objects are received as reception signals using the multiple reception antennas 31. At this time, the multiplexed transmission signals are separated from each reception signal, and a complex propagation path response represented by the product of the number of transmission antennas and the number of reception antennas is extracted. The data processing unit 6 performs array signal processing on the reception signals in the complex propagation path response represented by the product of the number of transmission antennas and the number of reception antennas as a virtual reception array.

[0019] (Virtual receiving array) The number of virtual receiving arrays will be described in detail with reference to Fig. 2. Fig. 2 is a diagram for explaining the virtual receiving arrays configured by the radar device 1 according to the first embodiment. In the first embodiment, as shown in Fig. 2(a), N t The transmitting antennas 24 are spaced apart by the same antenna spacing N along the horizontal direction. r In Figure 2(a), N t The transmitting antennas 24 are designated Tx#1 to Tx#N. t Also, as shown in Figure 2(b), N r The receiving antennas 31 are arranged at the same antenna spacing d along the horizontal direction. r The receiving antennas 31 are designated Rx#1 to Rx#N. rThe antenna spacing d is equal to half the wavelength of the transmitted wave TxW and the reflected wave RxW. However, it does not have to be exactly equal to half the wavelength, and the antenna spacing may be changed as appropriate. Furthermore, the antenna spacing between adjacent pairs of transmitting antennas 24 and receiving antennas 31 only needs to be considered to be the same for multiple pairs, taking into account design errors and variations.

[0020] N shown in Figure 2(a) t The transmitting antenna 24 and the N r 2(c) is generated by combining the virtual receiving antennas 31 with the virtual receiving array VRx#1 to VRx#(N t ×N r ) is shown by the N t If there are 10 receiving antennas, the number of receiving antennas is N t The virtual receiving antennas in the virtual receiving array are arranged at the same antenna spacing d along the horizontal direction.

[0021] The data processing unit 6 includes a signal conversion unit 61, a peak detection unit 62, a direction estimation unit 63, and a position estimation unit 64. The signal conversion unit 61 performs processing to separate frequency components based on the reflected waves of each target from a beat signal generated based on a signal received from the receiving antenna 31. In the first embodiment, the signal conversion unit 61 separates the frequency components using a fast Fourier transform (FFT). In the FFT processing, reception level and phase information are calculated for each frequency (frequency bin) set at a predetermined frequency interval. By applying the FFT processing to the input beat signal, a frequency spectrum is obtained in which peaks appear in frequency bins corresponding to the distance from the target. Furthermore, by arranging the frequency spectrum obtained by the first FFT processing in chronological order and performing a second FFT processing, a frequency spectrum is obtained in which peaks appear in frequency bins corresponding to the Doppler frequency. As a result, the signal conversion unit 61 obtains a two-dimensional power spectrum with distance and velocity as axes. Hereinafter, the first FFT processing may be referred to as a one-dimensional FFT or a distance FFT. The second FFT process may also be called a two-dimensional FFT or a velocity FFT.

[0022] The peak detection unit 62 detects peaks from the two-dimensional power spectrum obtained by the signal conversion unit 61. In the first embodiment, peaks showing power values ​​equal to or greater than a predetermined threshold are detected. As a peak detection method, a fixed threshold may be used, or a known algorithm such as CFAR (Constant False Alarm Rate) may be used.

[0023] The direction estimation unit 63 estimates the target direction (direction of arrival of radio waves) where the target exists based on the phase and amplitude information of the bin where the peak was detected. If multiple peaks are detected, the direction estimation unit 63 performs direction estimation for each peak. For direction estimation, known methods such as FFT-based BF (Beam Forming), MUSIC (Multiple Signal Classification), or ESPRIT (Estimation of Signal Parameters via Rotational Invariance Techniques) are used. Note that these methods are merely examples, and other methods may also be used.

[0024] The position estimation unit 64 calculates the relative position of the target using the distance to the target and the relative velocity to the target corresponding to the frequency bin detected by the peak detection unit 62, and the target direction obtained by the direction estimation unit 63. The relative position of the target obtained by the data processing unit 6 is stored in the memory 7.

[0025] The control device 10 controls the radar device 1 by rewriting the settings in the memory 7 of the signal processing device 4. The control device 10 also obtains the relative position of the target from the memory 7 at regular time intervals.

[0026] (Transmission timing control) Generally, radar equipment that performs time division multiplexing transmission has N t The transmitting antennas 24 are sequentially switched at a predetermined period T1 to transmit a transmitting signal (transmitting pulse). In this case, it takes T1×N t If such time division multiplexing transmission is repeated Nc times and Fourier frequency analysis is applied to detect the Doppler frequency, the Doppler frequency range in which the Doppler frequency can be detected without aliasing is ±1 / (2T1×N t ) Therefore, the Doppler frequency range in which the Doppler frequency can be detected without aliasing is the number of transmitting antennas N tThe Doppler frequency range indicates the range of relative velocities that the radar device 1 can detect or the maximum value of the relative velocities.

[0027] Therefore, in the first embodiment, the transmitting antenna 24 is not switched every time one transmission signal is transmitted, but rather a method is used in which transmission waves are transmitted continuously from one transmitting antenna 24 a predetermined number of times, Nc times (Nc≧2), and then the transmitting antenna 24 to be used for transmission is switched. FIG. 3 is a diagram for explaining a method for controlling transmission timing according to the first embodiment. As shown in FIG. 3, in this method, transmission waves are transmitted continuously from one transmitting antenna 24 (N t = 1), the transmission period from the same transmitting antenna can be shortened, making it possible to form a virtual receiving array while expanding the Doppler frequency range. However, with this method, a transmission delay of T1 × Nc occurs for each transmitting antenna 24, and when the transmitting antenna 24 is switched, a phase rotation that differs depending on the Doppler frequency is applied in accordance with this transmission delay. When such a phase rotation occurs, the accuracy of direction estimation in the virtual receiving array decreases.

[0028] One method for compensating for phase rotation is to use N t ×N r Of the (number of transmitting antennas × number of receiving antennas) virtual receiving antennas, at least N t One possible method is to arrange the transmitting and receiving antennas so that the arrangement positions of one virtual receiving antenna overlap, and to compensate for the phase and amplitude using the overlapping virtual receiving array. However, this method imposes restrictions on the arrangement of the transmitting and receiving antennas. Furthermore, if the phase cannot be calculated correctly, for example, when a drop in the received signal occurs at an overlapping virtual receiving antenna, the effect is distributed depending on the number of arrays in normal direction estimation, but in the above method, the compensation for phase rotation affects the entire system.

[0029] Therefore, in the first embodiment, when direction estimation is performed during reception control, phase rotation is compensated for using a method described later, thereby correctly configuring a virtual receiving array and improving direction estimation accuracy.

[0030] (Transmission control method and reception control method) Before describing the direction estimation method of the first embodiment, the flow of the transmission control method and reception control method in the radar device 1, which is the premise of the first embodiment, will be described with reference to Figs. 4 to 7. Fig. 4 is a flowchart showing the overall processing flow of the radar device 1 according to the first embodiment. As shown in Fig. 4, after startup, the radar device 1 first reads setting values ​​from the memory 7 as initial values ​​(step S1). These setting values ​​may be written by the control device 10. Thereafter, the radar device 1 performs transmission control (step S2) and reception control (step S3) in parallel.

[0031] The transmission control in step S2 of FIG. 4 will be described in detail with reference to FIG. 5. FIG. 5 is a flowchart showing a transmission control method of the radar device 1 according to the first embodiment. First, the transmission control unit 5 determines whether it is appropriate timing for the transmitter 2 to transmit a transmission signal (step S201). If it is not appropriate timing for transmission (step S201: NO), the transmitter 2 waits until it is appropriate timing for transmission. If it is appropriate timing for transmission (step S201: YES), the transmission control unit 5 determines whether it is necessary to switch the transmitting antenna 24 (whether it is the timing for switching) based on the number of times the transmission signal was transmitted from the transmitting antenna 24 that last transmitted the transmission signal and the set number of times Nc (step S202). Specifically, if the number of times the transmission signal was transmitted from the transmitting antenna 24 that last transmitted the transmission signal is less than the set number of times Nc, it is determined that switching of the transmitting antenna 24 is not necessary. On the other hand, if the number of times the transmission signal was transmitted from the transmitting antenna 24 that last transmitted the transmission signal has reached the set number of times Nc, it is determined that switching of the transmitting antenna 24 is necessary.

[0032] If switching is necessary (step S202: YES), the transmission control unit 5 switches from the current transmission changeover switch 23 to the transmission changeover switch 23 corresponding to the transmission antenna 24 that transmits the transmission wave (step S203). At this time, the number of times the transmission signal is transmitted from the transmission antenna 24, which is compared with the set number of times Nc, is reset. If switching is not necessary (step S202: NO), the transmission control unit 5 leaves the current transmission changeover switch 23 as the transmission antenna 24 that transmits the transmission wave. As a result, a chirp signal is transmitted from the transmission antenna 24 at the transmission timing of the time division multiplexing described above (step S204). Specifically, as explained using FIG. 3, N t The chirp signal is repeatedly transmitted Nc times for each of the transmitting antennas.

[0033] The transmission control unit 5 then determines whether an end command has been output from the control device 10 to stop the radar device 1 (step S205). Only if an end command has been output (step S205: YES), the transmission control unit 5 ends transmission control. If an end command has not been output (step S205: NO), the process returns to step S201 and loops until an end command is issued. A series of operations from steps S201 to S205 is called a transmission frame. The radar device 1 executes a transmission frame at regular time intervals. The transmission frame ends when an end command for the radar device 1 has been output, or, for example, when transmission of transmission waves has been completed a set number Nc of times for all of the transmitting antennas 24.

[0034] The reception control in step S3 in FIG. 4 will be described in detail with reference to FIGS. 6 and 7. FIGS. 6 and 7 are flowcharts showing a reception control method for the radar device 1 according to the first embodiment. Note that FIG. 7 shows processing branched from FIG. 6. First, the data processing unit 6 grasps the status of the transmission frame and determines whether the transmission frame has ended (step S301). If the transmission frame has not ended (step S301: NO), the signal conversion unit 61 waits to receive a beat signal between the A / D converted transmission signal and the reception signal. The signal conversion unit 61 determines whether reception of a predetermined number of samples of beat signals has been completed (step S302). If reception of the predetermined number of samples of beat signals has not been completed (step S302: NO), the signal conversion unit 61 continues to wait for reception until reception of the predetermined number of samples of beat signals has been completed.

[0035] If the reception of the predetermined number of samples of beat signals has been completed (step S302: YES), the signal conversion unit 61 performs a distance FFT on the beat signal (step S303) and stores the frequency spectrum obtained by the distance FFT in the memory 7 (step S304). Then, similar to the transmission control, the data processing unit 6 determines whether an end command to stop the radar device 1 has been output from the control device 10 (step S305). Only if an end command has been output (step S305: YES), the data processing unit 6 ends the transmission control. If an end command has not been output (step S305: NO), the process returns to step S301, and the process loops until an end command is issued.

[0036] If the transmission frame has ended (step S301: YES), the signal conversion unit 61 reads out the frequency spectrum of the distance FFT processed up to the end of the transmission frame (step S311). Next, the signal conversion unit 61 arranges the frequency spectrum of the distance FFT in time series and performs a velocity FFT to calculate a frequency spectrum corresponding to the Doppler frequency (step S312). Next, the signal conversion unit 61 adds up the absolute values ​​of the obtained frequency spectrum for all antennas (number of transmitting antennas × number of receiving antennas) to obtain a two-dimensional power spectrum with distance and velocity as its axes (step S313). Thereafter, the peak detection unit 62 detects peaks in this two-dimensional power spectrum that exceed a predetermined threshold (step S314). Then, the direction estimation unit 63 performs direction estimation for all peaks that exceed the threshold (step S315). The direction estimation process will be described later.

[0037] The position estimation unit 64 uses the target azimuth obtained by the azimuth estimation in step S315 and the distance and relative speed obtained from the peak position of the power spectrum to obtain relative position information as seen from the radar device 1 (step S316). Then, the obtained position information is output to the memory 7 (step S317). Note that when obtaining the position information, not only azimuth information but also time-series tracking may be performed, and information required for the control device 10 to perform such processing may be output.

[0038] (Direction estimation method) Details of the direction estimation in step S314 in Fig. 7 will be described with reference to Fig. 8. Fig. 8 is a flowchart showing the direction estimation method of the radar device 1 according to the first embodiment. As shown in Fig. 8, first, the direction estimation unit 63 reads the phase and amplitude of each antenna at the detected peak as an input signal (step S401), and uses them for direction estimation. Next, the direction estimation unit 63 selects one transmitting antenna 24 and N receiving antennas 31 from the combinations of the transmitting antennas 24 and N receiving antennas 31. rUsing an input signal corresponding to a combination (actual array) of the t-th transmitting antenna 24 and the N receiving antennas 31, a reference direction is estimated as a reference for calculating the amount of phase rotation that occurs in the input signal Xt when the transmitting antenna 24 is switched (step S402). r When the input signal obtained from the combination corresponding to the receiving antennas 31 is represented as Xt, it is expressed as the following equation (1). Xt=[X t_1 ,X t_2 ,…,X t_Nr ]···(1) where X t_r = rth receive antenna.

[0039] Next, the direction estimation unit 63 calculates an array response vector that serves as a reference when calculating the amount of phase rotation (step S403). t The array response vector in the receiving array is a t (θ t ), it can be expressed as the following equation (2). a t (θ t )=[a t_1 (θ t ),a t_2 (θ t ),…,a t_Nr (θ t )] T ···(2) where: T denotes matrix transposition.

[0040] Since the element spacing of the receiving array is d, a t_1 (θ t ) as the standard, a t (θ t ) is expressed as the following equation (3). a t (θ t )=[1,exp(-j2πdsin(θ t ) / λ),…, exp(-j2π(N r -1)dsin(θ t) / λ)] (3)

[0041] In practice, it is necessary to calculate the phase when the virtual receiving array VRx#1 is used as a reference. Therefore, the interval between the transmitting antennas 24 is taken into consideration and the phase is calculated as exp(-j2π(t-1)N r dsin(θ t ) / λ).

[0042] Furthermore, the direction estimation unit 63 calculates the input signal Xt and the array response vector a t (θ t ) and the phase rotation amount θ t_off is estimated (step S404). t_off is the input signal Xt and the array response vector a t (θ t ) are used to calculate as shown in the following equations (4) and (5). θ t_tmp =X t_1 / a t_1 (θ t )+X t_2 / a t_2 (θ t )+… +X t_Nr / a t_Nr (θ t )···(4) θ t_off =θ t_tmp / abs(θ t_tmp )···(5) Here, / abs(θ t_tmp ) is θ t_tmp The absolute value of each component is divided by the amplitude component, and the θ t_off In this case, only the phase information is output.

[0043] Then, the direction estimation unit 63 calculates the phase rotation amount θ t_off (Step S405). The signal with the phase rotation compensated is denoted as X t_cal Then, it is shown by the following equation (6). X t_cal =[X t_1 / θ t_off_1 ,X t_2 / θ t_off_2 ,…, X t_Nr / θ t_off_Nr ]···(6) In step S406, the direction estimation unit 63 calculates the phase rotation compensated signal X t_cal is stored in memory 7.

[0044] The direction estimating unit 63 determines whether the processing has been completed for all transmitting antennas (step S407). If the processing has not been completed for all transmitting antennas (step S407: NO), the processing from step S402 onwards is looped until the processing is completed. If the processing has been completed for all transmitting antennas (step S407: YES), the direction estimating unit 63 ends the loop and adjusts the input signal X so that it matches the arrangement of the virtual receiving array in order to perform direction estimation. t_cal (Step S408) If there are overlapping elements on the virtual receiving array, the signals are averaged between the overlapping elements.

[0045] Then, the direction estimator 63 calculates the input signal X mapped to the virtual receiving array arrangement. t_cal (Step S409). The direction estimation may be performed using a known method, as in Step S402. The result of the direction estimation is output to the position estimation unit 64 as the target direction. Finally, the direction estimation unit 63 determines whether or not processing has been completed for all peaks (Step S410). If not (Step S410: NO), the processing from Step S401 is repeated. If completed (Step S410: YES), the direction estimation is terminated.

[0046] As described above, according to the first embodiment, by continuously transmitting signals from one transmitting antenna 24, the transmission period from the same transmitting antenna can be shortened, thereby suppressing a reduction in the measurable range of relative velocities. Furthermore, by estimating the amount of phase rotation based on a reference direction estimated using an input signal corresponding to an array that combines one transmitting antenna 24 and multiple receiving antennas 31, it is possible to compensate for the phase rotation that occurs when the transmitting antennas 24 are switched. Therefore, the radar device 1 of the first embodiment can suppress a reduction in the measurable range of relative velocities without degrading the target detection accuracy. [Explanation of symbols]

[0047] 1 radar device, 2 transmitting unit, 3 receiving unit, 4 signal processing device, 5 transmission control unit, 6 data processing unit, 7 memory, 10 control device, 21 signal generating unit, 22 oscillator, 23 transmission selector switch, 24 transmitting antenna, 31 receiving antenna, 32 low noise amplifier, 33 mixer, 34 A / D converter, 61 signal converting unit, 62 peak detecting unit, 63 direction estimating unit, 64 position estimating unit.

Claims

1. a plurality of transmit antennas and a plurality of receive antennas; a transmission control unit that causes one of the plurality of transmission antennas to continuously transmit a signal a preset number of times, and switches the transmission antenna that transmits the signal when the transmission of the signal has been completed the preset number of times; a target azimuth estimation unit that estimates a target azimuth in which a target exists, The direction estimation unit estimating a phase rotation amount of the input signal that occurs when the transmission control unit switches the transmitting antenna, based on a reference direction estimated using an input signal corresponding to an array that combines one of the transmitting antennas and a plurality of the receiving antennas; Compensating for the phase rotation of the input signal using the estimated phase rotation amount; The target azimuth is estimated based on the input signal whose phase rotation has been compensated. Radar equipment.

2. The direction estimation unit calculating an array response vector serving as a reference for estimating the amount of phase rotation based on the reference azimuth; The phase rotation amount is estimated based on the array response vector and the input signal. The radar device according to claim 1 .

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