JP2020118644A - Arrival direction estimating device and arrival direction estimating method - Google Patents

Abstract

To provide arrival direction estimation technology with which it is possible to improve the accuracy of angle of each of a plurality of targets while eliminating a phase-wrap problem.SOLUTION: An arrival direction estimating device comprises an angle calculation unit and an estimation unit. The angle calculation unit calculates a first angle of each of a plurality of targets derived from a received signal obtained by a plurality of first receive antennas arranged at a first internal and a second angle of each of the plurality of targets derived from a received signal obtained by a plurality of second receive antennas arranged at a second internal wider than the first interval. The estimation unit estimates the arrival direction of a radio wave reflected by each of the plurality of targets on the basis of the plurality of first angles, the plurality of second angles and the phase-wrap angle of each of the plurality of second angles, and determines one among the second angles and phase-wrap angles as the arrival direction with respect to each of the plurality of targets.SELECTED DRAWING: Figure 1

Description

The present invention relates to a technique of estimating the arrival direction of a radio wave.

The radar device irradiates a radio wave and receives the radio wave (reflected wave) reflected from the target to estimate the arrival direction of the reflected wave. The method of estimating the direction of arrival is a method of calculating the direction of arrival (angle) from the information of the phase difference and the amplitude difference of the received signals obtained by the plurality of receiving antennas that receive the reflected waves.

JP 2000-230974 A

In calculating the direction of arrival (angle), the receiving antenna spacing is very important and greatly affects the angle accuracy and phase folding. There is a trade-off between angle accuracy and phase folding. Specifically, if the receiving antenna spacing is wide, the angular accuracy of the target is good, but phase folding is likely to occur, whereas if the receiving antenna spacing is narrow, phase folding is difficult to occur, but the angular accuracy of the target is Will get worse.

In the radar device disclosed in Patent Document 1, the angle at which the angles (azimuths) of the targets detected by the two receiving antenna pairs having different antenna intervals are the same as the angle of the target detected by the radar device. By adopting it as an angle, the angle accuracy of the target is improved while solving the problem of phase folding.

However, the radar device disclosed in Patent Document 1 cannot calculate the arrival direction (angle) corresponding to a plurality of targets whose distance to the radar device and relative speed to the radar device are similar to each other. ..

In view of the above problems, it is an object of the present invention to provide a direction-of-arrival estimation technique that can improve the angle accuracy of each of a plurality of targets while solving the problem of phase aliasing.

The arrival direction estimating apparatus according to the present invention includes a first angle of each of a plurality of targets derived from reception signals obtained by a plurality of first receiving antennas arranged at a first distance, and the first angle. An angle calculation unit that calculates a second angle of each of the plurality of targets derived from reception signals obtained by a plurality of second receiving antennas arranged at a second spacing wider than one spacing; And an estimation unit that estimates the arrival direction of the radio wave reflected from each of the plurality of targets, based on the first angle, the plurality of second angles, and the plurality of second angle return phases. , And the estimation unit is configured to set one of the second angle and the phase turning angle as the arrival direction for each of the plurality of targets (first configuration).

In the direction-of-arrival estimation apparatus having the first configuration, some of the plurality of first receiving antennas and some of the plurality of second receiving antennas are common receiving antennas (second Configuration).

Another arrival direction estimating apparatus according to the present invention comprises: a reception signal obtained by a first sub-array which is a combination of a plurality of reception antennas; and a first sub-array having the same shape as the first sub-array. A first angle of each of a plurality of targets derived by using a reception signal obtained by a second sub-array in which a first phase difference is generated, and a first angle having the same shape as the first sub-array. A fourth sub-array having a second phase difference different from the first phase difference between the received signal obtained by the third sub-array and the third sub-array and having the same shape as the third sub-array. An angle calculation unit that calculates a second angle of each of a plurality of targets that is derived using the received signal obtained in step S1, a plurality of the first angles, a plurality of the second angles, and a plurality of the plurality of the angles. An estimation unit that estimates the arrival direction of the radio wave reflected from each of the plurality of targets on the basis of the phase turn-back angle of each of the second angles. It is a configuration (third configuration) in which one of a second angle and the phase folding angle is set as the arrival direction.

In the arrival direction estimation device having any one of the first to third configurations, the estimation unit includes phase folding angles of each of the plurality of first angles, the plurality of second angles, and the plurality of second angles. From the combination with the above, one pair that minimizes the angular difference is found, and the arrival direction of the radio wave reflected from each of the plurality of targets is estimated based on the one pair (fourth configuration). Good.

In the arrival direction estimation device of any one of the first to third configurations, the estimation unit is configured to minimize the sum of angular differences between the first angle and the angle of arrival. The configuration (fifth configuration) may be used to estimate the arrival direction of the radio wave reflected from each target.

The arrival direction estimation method according to the present invention includes a first angle of each of a plurality of targets derived from reception signals obtained by a plurality of first reception antennas arranged at a first interval, and the first angle. An angle calculation step of calculating a second angle of each of the plurality of targets derived from reception signals obtained by a plurality of second receiving antennas arranged at a second spacing wider than one spacing; An estimation step of estimating the arrival direction of the radio wave reflected from each of the plurality of targets, based on the first angle, the plurality of second angles, and the phase turn-back angles of each of the plurality of second angles. , And in the estimation step, one of the second angle and the phase turning angle is set as the arrival direction for each of the plurality of targets (sixth configuration).

Another direction of arrival estimation method according to the present invention is to combine a received signal obtained by a first sub-array, which is a combination of a plurality of receiving antennas, and a first sub-array having the same shape as the first sub-array. A first angle of each of a plurality of targets derived by using a reception signal obtained by a second sub-array in which a first phase difference occurs, and a first angle having the same shape as the first sub-array. A fourth sub-array having a second phase difference different from the first phase difference between the received signal obtained by the third sub-array and the third sub-array and having the same shape as the third sub-array. An angle calculating step of calculating a second angle of each of the plurality of targets derived using the received signal obtained in step 1, a plurality of the first angles, a plurality of the second angles, and a plurality of the plurality of the first angles. An estimation step of estimating the arrival direction of the radio wave reflected from each of the plurality of targets based on the phase turn-back angle of each of the second angles. One of the second angle and the phase turning angle is the direction of arrival (seventh structure).

According to the arrival direction estimation technique according to the present invention, the angle accuracy of each of a plurality of targets can be improved while solving the problem of phase folding.

The figure which shows one structural example of a radar device. Diagram showing the positional relationship between the radar device and the target Diagram showing the positional relationship between the radar device and the target The flowchart which shows the flow of the 1st example of an angle calculation process and an estimation process. The flowchart which shows the flow of the 2nd example of an angle calculation process and an estimation process. The figure which shows the example of arrangement of the receiving antenna The figure which shows the other structural example of a radar apparatus.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings.

<1. Configuration of radar device>
FIG. 1 is a diagram showing a configuration of a radar device 1 according to this embodiment. The radar device 1 is mounted on a vehicle such as an automobile. When the radar device 1 is mounted on the front end of the host vehicle, the radar device 1 acquires the target data related to the target existing in front of the host vehicle using the transmitted wave. The target data includes the distance to the target, the relative speed of the target with respect to the radar device 1, and the like. However, since the radar device 1 according to the present embodiment will be described as an example of an arrival direction estimation device, only the part related to the arrival direction estimation will be described in the following description.

As shown in FIG. 1, the radar device 1 mainly includes a transmitter 2, receivers 3n and 3w, and a signal processor 4.

The receiving unit 3n includes a plurality of receiving antennas 31n. For example, the reception unit 3n is arranged along the left-right direction of the vehicle and includes four reception antennas 31n corresponding to the reception channels ch1 to ch4. The receiving unit 3w includes a plurality of receiving antennas 31w. For example, the reception unit 3w is arranged along the left-right direction of the vehicle and includes four reception antennas 31w corresponding to the reception channels ch5 to ch8.

The interval between the adjacent receiving antennas 31n is the first interval d1, and in the receiving unit 3w, the interval between the adjacent receiving antennas 31w is the second interval d2, which is wider than the first interval d1. Note that the plurality of first intervals d1 do not have to be exactly the same, and it is sufficient that the plurality of first intervals d1 can be considered to be the same in consideration of design errors and variations. It is preferable that the first interval d1 is equal to or less than a half wavelength of the reception signal obtained by the reception antenna 31n so that phase folding does not occur. However, even if phase wrapping occurs, it is possible to prevent the phase wrapping from occurring in the FOV depending on the setting of the FOV of the radar device 1. Therefore, the first interval d1 is the reception signal obtained by the receiving antenna 31n. May be larger than half wavelength. In this embodiment, the first distance d1 is set to be equal to or less than a half wavelength of the reception signal obtained by the reception antenna 31n. The plurality of second intervals d2 do not have to be exactly the same, and it is sufficient that the plurality of second intervals d2 can be considered to be the same in consideration of design errors and variations. In this embodiment, the second interval d2 is set to be larger than the half wavelength of the reception signal obtained by the reception antenna 31w.

As described above, in the receiving unit 3n, the interval between the adjacent receiving antennas 31n is the first interval d1, and in the receiving unit 3w, the interval between the adjacent receiving antennas 31w is wider than the first interval d1. However, the basic configurations of the receiving unit 3n and the receiving unit 3w are the same. Therefore, in the following description, the receiving unit 3n and the receiving unit 3w will be appropriately described as the receiving unit 3 without making a distinction.

The transmitter 2 includes a signal generator 21 and a transmitter 22. The oscillator 22 modulates the signal generated by the signal generator 21 to generate a transmission signal. The transmission antenna 23 converts the transmission signal into a transmission wave TW and outputs it.

The receiving unit 3 includes a plurality of receiving antennas 31 and a plurality of individual receiving units 32 connected to the plurality of receiving antennas 31. In the present embodiment, the receiving unit 3 includes, for example, four receiving antennas 31 and four individual receiving units 32. The four individual receiving units 32 correspond to the four receiving antennas 31, respectively. Each reception antenna 31 receives the reflected wave RW from the object to acquire a reception signal, and each individual reception unit 32 processes the reception signal obtained by the corresponding reception antenna 31.

Each individual receiving unit 32 includes a mixer 33 and an A/D converter 34. The reception signal obtained by the reception antenna 31 is amplified by a low noise amplifier (not shown) and then sent to the mixer 33. The transmission signal from the transmitter 22 of the transmitter 2 is input to the mixer 33, and the transmission signal and the reception signal are mixed in the mixer 33. As a result, a beat signal having a beat frequency that is the difference between the frequency of the transmission signal and the frequency of the reception signal is generated. The beat signal generated by the mixer 33 is converted into a digital signal by the A/D converter 34 and then output to the signal processing device 4.

The signal processing device 4 includes a microcomputer including a CPU (Central Processing Unit), a memory 41, and the like. The signal processing device 4 stores various data to be calculated in the memory 41, which is a storage device. The memory 41 is, for example, a RAM (Random Access Memory). The signal processing device 4 includes a transmission control unit 42, a Fourier transform unit 43, and a data processing unit 44, which are functions implemented by software in a microcomputer. The transmission controller 42 controls the signal generator 21 of the transmitter 2. The data processing unit 44 includes a peak extraction unit 45, an angle calculation unit 46, and an estimation unit 47.

In the Fourier transform unit 43, the reflected waves from the plurality of targets are received by the receiving antenna 31 in a state of being overlapped with each other. Therefore, from the beat signal generated based on the received signals, the frequency components based on the reflected waves of the respective targets are received. Is performed (for example, FFT (Fast Fourier Transfer) processing). In the FFT processing, the reception level and the phase information are calculated for each frequency point (sometimes called a frequency bin) set at a predetermined frequency interval.

The peak extraction unit 45 detects a peak from the result of FFT processing or the like performed by the Fourier transform unit 43.

The angle calculation unit 46 calculates the first angle of each of the plurality of targets derived from the reception signals obtained by the plurality of reception antennas 31n, using a well-known azimuth calculation process such as DBF and MUSIC. The angle calculation unit 46 also calculates the second angle of each of the plurality of targets derived from the reception signals obtained by the plurality of reception antennas 31w, using a well-known azimuth calculation process such as DBF or MUSIC.

Hereinafter, a case will be described in which two targets having similar distances to the radar device 1 and relative speeds to the radar device 1 are derived. The angle calculation unit 46 derives the two targets α1 and α2 shown in FIG. 2 from the reception signals obtained by the plurality of reception antennas 31n, and calculates the first angle θ _α1 of the target _α1 and the first target α2 of the target α2. The angle θ _{α2 of} is calculated.

The angle calculation unit 46 derives the two targets β1 and β2 shown in FIG. 3 from the reception signals obtained by the plurality of reception antennas 31w, and outputs the second angle θ _β1 of the target _β1 and the second target β2 of the target β2. The angle θ _{β2 of} is calculated. At the second angles θ _β1 and θ _β2 , although the accuracy is high, phase folding occurs, so that the original position of the target β1 may be the phase folding position β1′ or β1″ shown in FIG. The original position of 1 may be the phase folding position β2′ or β2″ shown in FIG. The number of phase turns is determined by the relationship between the above-described second interval d2 and the wavelength of the reception signal obtained by the reception antenna 31w, and is not limited to the number in this embodiment. In the following description, _'' using, theta _.beta.2 as the phase folding angle of the second angle theta _.beta.2 and theta _{.beta.1 'and} theta _{.beta.2 "theta .beta.1} as the phase folding angle of the second angle theta _.beta.1 used. The phase folding angles θ _β1 ′, θ _β1 ″, θ _β2 ′, and θ _β2 ″ are the angles of the phase folding positions β1 ′, β1 ″, β2 ′, and β1 ″, respectively.

The estimation unit 47 _{calculates 2} based on the first angles θ _α1 and θ _α2 , the second angles θ _β1 and θ _β2 , and the phase folding angles θ _β1 ′, θ _β1 ″, θ _β2 ′, and θ _β2 ″. The direction of arrival of the radio waves reflected from each of the two targets is estimated. The estimation unit 47 can solve the phase folding problem of each of the targets β1 and β2 by using the first angles θ _α1 and θ _α2 .

Then, the estimation unit 47 sets one of the second angle θ _{β1 and the} phase folding angles θ _β1 ′ and θ _β1 ″ for one target as the arrival direction of the radio wave reflected from the one target. The estimation unit 47 sets one of the second angle θ _{β2 and the} phase turning angles θ _β2 ′ and θ _β2 ″ for the other target as the arrival direction of the radio wave reflected from the one target. Thereby, the angle accuracy of each of the plurality of targets can be improved.

The estimation unit 47 outputs the estimated azimuth (angle) where the target is present to the memory 41, the vehicle control ECU 5, and the like.

<2. First example of angle calculation processing and estimation processing>
FIG. 4 is a flowchart showing a flow of a first example of the calculation process executed by the angle calculation unit 46 and the estimation process executed by the estimation unit 47.

The angle calculation unit 46 calculates the first angles θ _α1 and θ _α2 (step S1). Next, the angle calculator 46 calculates the second angles θ _β1 and θ _β2 (step S2). The order of steps S1 and S2 may be exchanged, or the steps may be executed in parallel.

After completion of steps S1 and S2, either the angle calculation unit 46 or the estimation unit 47 calculates the phase folding angles θ _β1 ′, θ _β1 ″, θ _β2 ′, and θ _β2 ″ (step S3 ).

In step S4 following step S3, the estimation unit 47 calculates twelve different angle differences. The twelve angular differences are (1) to (12) below. Note that each angle difference is an absolute value.
(1) An angle difference between the first angle θ _α1 and the phase folding angle θ _β1 ′ (2) An angle difference between the first angle θ _α1 and the phase folding angle θ _β2 ′ (3) A first angle θ _α1 Angle difference between second angle θ _β1 (4) Angle difference between first angle θ _α1 and second angle θ _β2 (5) Angle difference between first angle θ _α1 and phase folding angle θ _β1 ″ (6) Angle difference between the first angle θ _α1 and the phase folding angle θ _β2 ″ (7) Angle difference between the first angle θ _α2 and phase folding angle θ _β1 ′ (8) First angle θ _α2 Angle difference between phase turnaround angle θ _β2 ′ (9) Angle difference between first angle θ _α2 and second angle θ _β1 (10) Angle difference between first angle θ _α2 and second angle θ _β2 (11) Angle difference between the first angle θ _α2 and the phase folding angle θ _β1 ″ (12) Angle difference between the first angle θ _α2 and the phase folding angle θ _β2 ″

In step S5 subsequent to step S4, the estimation unit 47 finds (identifies) one pair having the smallest angular difference from the 12 ways, and determines the second angle or the phase folding angle belonging to the identified pair as one of The arrival direction of the radio wave reflected from the target. Hereinafter, the description will be continued by exemplifying the case where the one pair with the smallest angle difference is (1) described above.

In step S6 subsequent to step S5, the estimation unit 47 calculates three types of angle differences regarding the other target. When one pair with the smallest angle difference is (1) above, the three angle differences in step S6 are (8), (10), and (12) above.

In step S7 following step S6, the estimation unit 47 finds (identifies) one pair having the smallest angle difference from the above three ways, and determines the second angle or the phase folding angle belonging to the identified pair. , The arrival direction of the radio wave reflected from the other target.

<3. Second example of angle calculation processing and estimation processing>
FIG. 5 is a flowchart showing a flow of a second example of the calculation process executed by the angle calculation unit 46 and the estimation process executed by the estimation unit 47. In FIG. 5, the same steps as those in FIG. 4 are designated by the same reference numerals, and detailed description thereof will be omitted.

After the end of step S3, the estimation unit 47 executes the process of step 8. The estimation unit 47 makes the first assumption that the target α1 and the target β1 are one target, and the target α2 and the target β2 are the other targets, and the above (1) and (3 ), (5) find one pair with the smallest angle difference (identify), and select one pair with the smallest angle difference from (8), (10) and (12) above. After finding (specifying), the sum of the angular differences of the two specified pairs is calculated (step S8). Next, the second assumption is made that the target α1 and the target β2 are one target, and the target α2 and the target β1 are the other target, and the above (2), (4), Find (specify) one pair with the smallest angle difference from (6), and find one pair with the smallest angle difference from (7), (9), and (11) above. Then, the sum of the angular differences of the two specified pairs is calculated (step S9). In addition, the execution order of steps S8 and S9 may be exchanged, or the steps may be executed in parallel.

After completion of steps S8 and S9, the estimation unit 47 adopts the above-mentioned first assumption when the total sum calculated in step S8 is smaller than the total sum calculated in step S9, and the total sum calculated in step S9 is calculated in step S8. If the sum is smaller than the sum calculated in step 2, the above second assumption is adopted (step S10). Then, when adopting the above-mentioned first assumption, the estimating unit 47 sets the second angle or the phase turning angle belonging to the pair identified in step S8 as the arrival direction of the radio wave reflected from the target, and the above-described first angle. When the assumption 2 is adopted, the second angle or the phase turning angle belonging to the pair identified in step S9 is set as the arrival direction of the radio wave reflected from the target (step S10).

Which of the above-mentioned “first example of angle calculation processing and estimation processing” and “second example of angle calculation processing and estimation processing” that is superior is uncertain. Therefore, for example, it may be determined which of the plurality of targets is to be adopted in consideration of the result of the simulation or the experiment in which the assumed arrangement of the plurality of targets and the assumed specifications of the radar device 1 are considered.

<4. Other>
Various technical features disclosed in this specification can be variously modified in addition to the above-described embodiment without departing from the spirit of the technical creation. In addition, a plurality of embodiments and modifications shown in the present specification may be combined and implemented within a possible range.

In the above-described embodiment, the radar device 1 is configured to include the four receiving antennas 31n and the four receiving antennas 31w, but for example, the four receiving antennas 31n and the four receiving antennas 31w are shown in FIG. Six receiving antennas 31 may be provided. The receiving channel ch11 shown in FIG. 6 is used instead of the receiving channels ch1 and CH5 shown in FIG. 1, the receiving channel ch12 shown in FIG. 6 is used instead of the receiving channel ch2 shown in FIG. 1, and the receiving channel shown in FIG. ch13 is used instead of the reception channels ch3 and CH6 shown in FIG. 1, and the reception channels ch14 to Ch16 shown in FIG. 6 are used instead of the reception channels ch4, CH7, and CH8 shown in FIG. 1, respectively.

When the six receiving antennas 31 shown in FIG. 6 are provided, a part of the plurality of receiving antennas having an antenna interval of the first interval d1 and one of the plurality of receiving antennas having the antenna interval of the second interval d2 are provided. The unit and the unit become a common receiving antenna. Therefore, when the six receiving antennas 31 shown in FIG. 6 are provided, the number of receiving antennas 31 can be reduced, and the number of individual receiving units 32 can be reduced accordingly.

Further, the radar device 1 described in the above-described embodiment is a radar device that solves the problem caused by the trade-off relationship between the angle accuracy according to the reception antenna interval and the phase folding. Here, for example, when using an azimuth calculation process that calculates an angle from the phase difference between the sub-arrays such as ESPRIT and DoA-matrix, a problem resulting from the trade-off relationship between the angle accuracy and the phase folding according to the phase difference Need to be resolved. In the trade-off relationship between the angle accuracy according to the phase difference and the phase folding, the larger the movement amount between the sub-arrays, the better the angular accuracy of the target, but the more likely the phase folding is to occur. If is smaller, phase folding is less likely to occur, but the angular accuracy of the target is worse.

Therefore, the radar device 1 shown in FIG. 1 may be changed to the configuration shown in FIG. 7, and the angle calculation unit 46 may calculate the angle as follows. The other configurations and operations are basically the same as those of the above-described embodiment, and thus the description thereof will be omitted.

The angle calculation unit 46 includes a reception signal obtained by the first sub-array that is a combination of the 1ch reception antenna 31 and the 2ch reception antenna 31, and a second combination that is the combination of the 2ch reception antenna 31 and the 3ch reception antenna 31. 2 is derived from the received signals obtained by the sub-array of FIG. 2 to calculate the first angle θ _α1 of the target _α1 and the first angle θ _α2 of the target α2. ..

The angle calculation unit 46 includes a reception signal obtained by the third sub-array which is a combination of the reception antenna 31 of 1ch and a reception antenna 31 of 2ch, and a fourth combination which is a combination of the reception antenna 31 of 3ch and the reception antenna 31 of 4ch. The two targets β1 and β2 shown in FIG. 3 are derived from the received signal obtained by the sub-array and the second angle θ _β1 of the target _β1 and the second angle θ _β2 of the target _β2 are calculated. ..

The radar device 1 illustrated in FIG. 7 can solve the problem caused by the trade-off relationship between the angle accuracy according to the phase difference and the phase folding. Therefore, the angle accuracy of each of the plurality of targets can be improved while solving the problem of phase folding.

Further, although the in-vehicle radar device has been described in the above-described embodiment, the present invention is also applicable to an infra-radar device installed on a road or the like, an aircraft surveillance radar device, and the like.

DESCRIPTION OF SYMBOLS 1 radar device 2 transmitter 3 receiver 31, 31n, 31w receiving antenna 4 signal processor 46 angle calculator 47 estimator

Claims (7)

At a first angle of each of a plurality of targets derived from reception signals obtained by a plurality of first receiving antennas arranged at a first interval, and at a second interval wider than the first interval. An angle calculation unit that calculates a second angle of each of the plurality of targets derived from the reception signals obtained by the plurality of second reception antennas arranged,
An estimation unit that estimates the arrival direction of the radio wave reflected from each of the plurality of targets, based on the plurality of first angles, each of the plurality of second angles, and each of the plurality of second angle return phases. When,
Equipped with
The said estimation part is an arrival direction estimation apparatus which makes one of the said 2nd angle and the said phase folding|turning angle the said arrival direction about each of said some target. The arrival direction estimation apparatus according to claim 1, wherein a part of the plurality of first receiving antennas and a part of the plurality of second receiving antennas are common receiving antennas. A second received signal obtained by the first sub-array that is a combination of a plurality of receiving antennas and a second sub-array having the same shape as the first sub-array and having the first phase difference are generated. A first angle of each of a plurality of targets derived using a received signal obtained by the sub-array, and a received signal obtained by a third sub-array having the same shape as the first sub-array; And a received signal obtained by a fourth sub-array having the same shape as the third sub-array and having a second phase difference different from the first phase difference between the third sub-array and the third sub-array. An angle calculation unit that calculates a second angle of each of the plurality of targets,
An estimation unit that estimates the arrival direction of the radio wave reflected from each of the plurality of targets, based on the plurality of first angles, each of the plurality of second angles, and each of the plurality of second angle return phases. When,
Equipped with
The said estimation part is an arrival direction estimation apparatus which makes one of the said 2nd angle and the said phase folding|turning angle the said arrival direction about each of said some target. The estimation unit finds one pair with the smallest angle difference from a combination of a plurality of the first angles, a plurality of the second angles, and a plurality of the phase folding angles of the second angles, The arrival direction estimation apparatus according to any one of claims 1 to 3, which estimates an arrival direction of a radio wave reflected from each of the plurality of targets based on the one pair. The estimation unit estimates the arrival direction of the radio wave reflected from each of the plurality of targets so that the total sum of the angle differences between the first angle and the angle of the arrival direction is minimized. The arrival direction estimation device according to any one of 1 to 3. At a first angle of each of a plurality of targets derived from reception signals obtained by a plurality of first receiving antennas arranged at a first interval, and at a second interval wider than the first interval. An angle calculation step of calculating a second angle of each of the plurality of targets derived from the reception signals obtained by the plurality of arranged second reception antennas,
An estimation step of estimating the arrival direction of the radio wave reflected from each of the plurality of targets, based on the plurality of first angles, the plurality of second angles, and the plurality of second angle return phases. When,
Equipped with
The arrival direction estimation method in which, in the estimation step, one of the second angle and the phase turning angle is set as the arrival direction for each of the plurality of targets. A second received signal obtained by the first sub-array that is a combination of a plurality of receiving antennas and a second sub-array having the same shape as the first sub-array and having the first phase difference are generated. A first angle of each of a plurality of targets derived using a received signal obtained by the sub-array, and a received signal obtained by a third sub-array having the same shape as the first sub-array; And a received signal obtained by a fourth sub-array having the same shape as the third sub-array and having a second phase difference different from the first phase difference between the third sub-array and the third sub-array. An angle calculation step of calculating a second angle of each of the plurality of targets,
An estimation step of estimating the arrival direction of the radio wave reflected from each of the plurality of targets, based on the plurality of first angles, the plurality of second angles, and the plurality of second angle return phases. When,
Equipped with
The arrival direction estimation method in which, in the estimation step, one of the second angle and the phase turning angle is set as the arrival direction for each of the plurality of targets.

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