WO2023188142A1 - Azimuth detection device and azimuth detection method - Google Patents

Abstract

An azimuth detection device (100) comprises: a signal reception unit (107) that includes an antenna array in which a plurality of antennas (101) are disposed at unequal intervals, and that receives incoming signals with the antenna array; and a signal processing circuit (110) that, if a plurality of incoming signals are included in each of one or more predetermined bands from the incoming signals, separates the incoming signals, calculates, in a specific frequency, an inter-antenna phase difference which is a phase difference between the plurality of antennas (101) from a frequency component of each incoming signal, and estimates an incoming azimuth of each incoming signal from the inter-antenna phase difference.

Description

Direction finding device and direction finding method

The present disclosure relates to a direction finding device and a direction finding method.

As a direction finding device that estimates the direction of arrival of a plurality of signals included in a wide frequency band, a direction finding device that uses an irregularly spaced antenna array in which a plurality of antennas are arranged at irregular intervals is known. Even if the signal is included in a wide frequency band, if it is a narrowband signal that has a narrow frequency band, the phase relationship between the signals received by each antenna of an unevenly spaced antenna array, specifically, between the antennas. By using the phase difference between the antennas, which is the phase difference between the antennas, the direction of arrival of the signal can be estimated.

As a technique for estimating the direction of arrival of a narrowband signal using an unevenly spaced antenna array, Patent Document 1 discloses a method of combining a plurality of unevenly spaced subarrays with subarray spacings such that the ratio of the subarray spacings is a prime number ratio or an irrational number. A method is disclosed that uses an antenna array arranged at irregular intervals to include at least one set of antennas.

On the other hand, in recent years, signals have become increasingly broadband, and there is a need for a technology that can estimate the direction of arrival of multiple broadband signals included in a wide frequency band, or in other words, the direction of arrival of signals with a wide frequency band.

Japanese Patent Application Publication No. 10-253730

In a wideband signal, the phase difference between antennas changes at different frequencies even within the signal band, so a narrowband signal estimation technique such as that described in Patent Document 1 is based on the premise that the phase difference between antennas is fixed. In this case, information in a wide frequency band cannot be used effectively.

Another possible method is to use an unevenly spaced antenna array as a direction finding device to estimate the direction of arrival of multiple signals included in a wide frequency band, but when estimating the direction of arrival of a wideband signal, Since the phase difference between antennas changes at different frequencies, information in a wide frequency band cannot be used effectively.

Therefore, one or more aspects of the present disclosure aim to enable accurate estimation of the direction of arrival of a wideband signal.

A direction finding device according to an aspect of the present disclosure includes an antenna array in which a plurality of antennas are arranged at unequal intervals, a signal receiving unit that receives an incoming signal with the antenna array, and a direction finding unit that receives a predetermined direction from the incoming signal. a signal separation and detection section that separates and detects the incoming signals if one or more bands include a plurality of incoming signals; A phase difference information calculation unit that calculates a phase difference between antennas, which is a phase difference, at a specific frequency; and a direction of arrival estimation unit that estimates the direction of arrival of each of the incoming signals from the phase difference between the antennas. Features.

In a direction finding method according to an aspect of the present disclosure, an incoming signal is received by an antenna array in which a plurality of antennas are arranged at unequal intervals, and a plurality of incoming signals are detected for each of one or more predetermined bands from the incoming signal. is included, the incoming signal is detected, and from the frequency components of each of the detected incoming signals, an inter-antenna phase difference, which is a phase difference between the plurality of antennas, is calculated at a specific frequency. The method is characterized in that the direction of arrival of each of the arriving signals is estimated from the phase difference between the antennas.

According to one or more aspects of the present disclosure, it is possible to accurately estimate the direction of arrival of a wideband signal.

1 is a block diagram schematically showing the configuration of a direction finding device according to Embodiments 1 and 2. FIG. FIG. 2 is a schematic diagram illustrating an example of an inter-antenna phase difference between different antennas of one wideband signal. 1 is a block diagram schematically showing the configuration of a signal processing circuit in Embodiment 1. FIG. 3 is a flowchart illustrating an example of a process for calculating a phase difference between antennas. FIG. 2 is a block diagram schematically showing the configuration of a signal processing circuit in Embodiment 2. FIG. (A) and (B) are block diagrams showing an example of a hardware configuration.

Embodiment 1.
FIG. 1 is a block diagram schematically showing the configuration of a direction finding device 100 according to the first embodiment.
The direction finding device 100 includes a plurality of antennas 101, a plurality of filters 102, a high frequency signal generation circuit 103, a plurality of mixers 104, a plurality of amplifiers 105, and a plurality of A/D (Analog/Digital) converters 106. and a signal processing circuit 110.
Here, the antenna 101, the filter 102, the mixer 104, the high frequency signal generation circuit 103, the amplifier 105, and the A/D converter 106 are also referred to as a signal receiving section 107.

The plurality of antennas 101 are arranged at unequal intervals and constitute an antenna array. It is assumed that the intervals at which the plurality of antennas 101 are arranged are set so that the arrival direction of the signal can be detected according to the known technique described in Patent Document 1 and the like. Therefore, the antenna array in which the plurality of antennas 101 are arranged at unequal intervals receives incoming signals over a wide band as received signals. A received signal received by each of the plurality of antennas 101 is provided to a plurality of filters 102 provided corresponding to each of the plurality of antennas 101.

The filter 102 filters out undesired components contained in the received signal. The filter reception signals processed by each of the plurality of filters 102 are provided to a plurality of mixers 104 provided corresponding to each of the plurality of filters 102.

The high frequency signal generation circuit 103 generates a high frequency signal that is a predetermined high frequency signal. The high frequency signal is provided to mixer 104.

The mixer 104 mixes the filter reception signal from the filter 102 and the high frequency signal from the high frequency signal generation circuit 103 to frequency convert the filter reception signal and filter out undesired components. A processed signal, which is a signal processed by each of the plurality of mixers 104, is provided to a plurality of amplifiers 105 provided corresponding to each of the plurality of mixers 104.

The amplifier 105 amplifies the processed signal from the mixer 104. The processed signals amplified by each of the plurality of amplifiers 105 are given as amplified signals to the plurality of A/D converters 106 provided corresponding to each of the plurality of amplifiers 105.

The A/D converter 106 converts the amplified signal from the amplifier 105 into an incoming signal by digitizing it. The incoming signal converted by each of the plurality of A/D converters 106 is provided to a signal processing circuit 110.

As described above, the signal receiving unit 107 includes an antenna array in which a plurality of antennas 101 are arranged at unequal intervals, and receives a plurality of incoming signals with the antenna array.

The signal processing circuit 110 is a signal processing unit that processes incoming signals that are digital signals from the plurality of A/D converters 106.
Here, the signal processing circuit 110 estimates the direction of arrival of a signal from the inter-antenna phase difference of the signal received by an antenna array in which a plurality of antennas 101 are arranged at unequal intervals.

First, the inter-antenna phase difference of the incoming signal received by the irregularly spaced antenna array will be explained. The inter-antenna phase difference φ( _m , n, k, θ) of the frequency component of the frequency kΔf of the received signal arriving from the direction θ at the antenna m and the antenna n with the antenna spacing d m, n is as follows. It is expressed by equation (1).

Here, c represents the speed of light, Δf represents the discrete frequency interval, and k represents the index of the discrete frequency.

From equation (1), it can be seen that the inter-antenna phase difference changes linearly with the frequency kΔf, and the inter-antenna phase difference changes at different frequencies. It can also be seen that in the case of a wideband signal, the phase difference between antennas changes significantly.

The reception frequency bandwidth of a wideband signal varies depending on the application, but is, for example, a bandwidth from several hundred MHz to several GHz. Furthermore, the inter-antenna phase difference also changes linearly with respect to each of the antenna spacing d _m,n and the sine sin θ of the signal arrival direction. FIG. 2 shows an example of the inter-antenna phase difference between different antennas for one broadband signal.

FIG. 3 is a block diagram schematically showing the configuration of the signal processing circuit 110.
The signal processing circuit 110 functions as a signal separation detection section 111, a phase difference information calculation section 112, and a direction of arrival estimation section 113.

The signal separation and detection unit 111 separates the incoming signal and detects the incoming signal. For example, if a plurality of incoming signals are included in each of one or more predetermined bands, the signal separation and detection unit 111 separates the incoming signal received by the signal receiving unit 107 and detects the incoming signal. do.

Specifically, for example, the signal separation and detection unit 111 divides an incoming signal in a wide frequency band into one or more subbands using a filter bank. Then, the signal separation detection unit 111 separates the plurality of signals by repeating assigning a signal band detected in the frequency domain to a signal detected in the time domain in each subband for each processing unit time. and detect it. Note that when detecting a signal band, the signal separation and detection unit 111 calculates a set of frequency components of the signal. The set of frequency components calculated here is given to the phase difference information calculation section 112.

For example, the signal separation detection unit 111 can use the signal separation detection method described in Non-Patent Document 1 below. The technology described in Non-Patent Document 1 divides a wide frequency band into multiple subbands using a filter bank, and assigns a signal band detected in the frequency domain to a signal detected in the time domain in each subband as a processing unit. By repeating each time, multiple signals can be separated and detected. Since a set of frequency components of the signal is calculated when detecting a signal band, the phase difference information calculation unit 112 can utilize the set of frequency components.

It is assumed that in the signal separation and detection unit 111 of the first embodiment, one signal band is assigned to a signal, and one set of frequency components corresponding to the signal band is calculated. Further, the signal separation and detection unit 111 may use other methods as long as they can separate and detect a plurality of signals. Even if the set of frequency components of the detected signal is not calculated in that method, the set of frequency components may be calculated after the signal is detected.
Non-patent document 1: Takafumi Nagano, Wataru Tsujita, "Real-time pulse detection method from wideband signal", IEICE Technical Report, SANE2021-3, pp. 11-14, May 2021

The phase difference information calculation unit 112 calculates the inter-antenna phase difference of the incoming signal. For example, the phase difference information calculation unit 112 specifies the inter-antenna phase difference, which is the phase difference between the plurality of antennas 101, from the frequency components of each of the one or more incoming signals separated and detected by the signal separation and detection unit 111. Calculated at the frequency of

Specifically, the phase difference information calculation unit 112 calculates the inter-antenna phase difference at a specific frequency from the set of frequency components from the signal separation detection unit 111. Note that, instead of the inter-antenna phase difference, the phase difference information calculation unit 112 calculates the peak component of the DFT (Discrete Fourier Transformation) of the inter-antenna product of the signal frequency components, corrected to a value at a specific frequency. It's okay.

For example, the inter-antenna product z (m, n, k, θ) between antenna m and antenna n of the frequency component of frequency kΔf of the signal at arrival direction θ is expressed by the following equation (2).

Here, it is assumed that the inter-antenna product is calculated after converting the frequency component of the signal received by antenna n into a conjugate complex number. Further, a(m, n, k, θ) represents intensity, and j represents an imaginary unit.

In calculating the phase difference between antennas, first, in order to make the phase difference between antennas a phase difference at a specific frequency, and to improve the S/N ratio, the frequency components within the signal band of the detected signal are calculated. For the inter-antenna product z(m, n, k), k=k _min , . . . , k _max , the DFT in the frequency direction is calculated using the following equation (3). Here, the direction of arrival of the signal is assumed to be unknown.

Here, L is the DFT length, and when zero padding is not performed, L=k _max −k _min +1.

When the rate of change of the inter-antenna phase difference matches the discrete frequency of the DFT, in other words, when the peak position of the DFT matches the discrete frequency of the DFT, and if the discrete frequency is l _peak , then the DFT's The deflection angle argZ (m, n, lpeak) of the peak component becomes the inter-antenna phase difference at the frequency k _min Δf. If the peak position of the DFT does not match the discrete frequency of the DFT, it is desirable to estimate the accurate peak position and correct the inter-antenna phase difference according to that position.

In order to accurately estimate the DFT peak position, it is effective to improve the S/N ratio of the DFT peak component. Since the rate of change of the inter-antenna phase difference for different antenna spacings is different, the peak positions of the DFT of the inter-antenna products of frequency components in an unevenly spaced antenna array are usually different. However, if the DFT is calculated after zero padding the product between each antenna so that the DFT length between each antenna is the reciprocal ratio of the antenna spacing, it is possible to align the DFT peak positions of the products between antennas with different antenna spacings. can.

The reference for the peak position is l = 0, and if Z (m, n, - l) = Z (m, n, L - l), then the DFT of the inter-antenna product with different antenna spacing in the positive and negative discrete frequency ranges is Peak positions can be aligned. When the peak positions are aligned, the S/N ratio can be improved by calculating the absolute value of the DFT between each antenna and adding the absolute values. Since the peak of the DFT of the antenna-to-antenna product is sharper in a DFT with a short zero-padded DFT length, the addition process may be a weighted average in which the weight of the DFT with a short zero-padded DFT length is increased. The DFT peak position may be estimated from the summed value after aligning the DFT peak positions between each antenna in this way, calculating and adding the absolute values.

The DFT peak position of the antenna-to-antenna product of the signal frequency component can be estimated with high accuracy by calculating a curve passing through the peak and points around it and estimating the peak position as a real number. For example, the phase difference information calculation unit 112 calculates a parabola passing through three points including the peak and two points on both sides of the peak, and estimates the horizontal axis position of the focus of the parabola as the peak position. As the curve, not only a parabola but also any curve having a maximum point may be used. When the estimated peak position is expressed by the following equation (4), the corrected inter-antenna phase difference at the frequency k _min Δf is expressed by the following equation (5).

Next, a specific frequency used by the phase difference information calculation section 112 will be explained.
In the above equation (5), the specific frequency is expressed as k _min Δf. This means that in the DFT stage of equation (3) above, if the frequency in the k direction of z (m, n, k) matches the discrete _frequency of the DFT, the This is because the declination angle becomes the inter-antenna phase difference at the frequency k _min Δf. On the other hand, if the frequency in the k direction of z(m, n, k) does not match the discrete frequency of DFT, the second term on the right side of equation (5) above calculates the phase difference at the frequency k _min Δf. Corrections have been made so that Note that when the frequency of z(m, n, k) in the k direction matches the discrete frequency of DFT, the second term on the right side of the above equation (5) becomes "0".

Note that using the estimated peak position shown in equation (4) above, the inter-antenna phase difference at a specific frequency k _min Δf is corrected to the inter-antenna phase difference at another frequency k _ref Δf. be able to. Specifically, as shown in equation (6) below, the inter-antenna phase difference at frequency k _min Δf can be corrected to the inter-antenna phase difference at frequency k _ref Δf.

FIG. 4 is a flowchart illustrating an example of a process in which the phase difference information calculation unit 112 calculates the inter-antenna phase difference in the first embodiment.
First, the phase difference information calculation unit 112 determines that the length in the frequency direction of the inter-antenna product of the frequency components between each antenna for each of the one or more incoming signals detected by the signal separation and detection unit 111 is equal to the interval between the plurality of antennas 101. The inter-antenna product between each antenna is zero-padded so as to have a reciprocal ratio, and then the DFT is calculated in the frequency direction (S10).

Next, the phase difference information calculation unit 112 adds the absolute values of the calculation results of the DFT between each antenna (S11).
Then, the phase difference information calculation unit 112 detects the peak position of DFT between each antenna (S12).
Subsequently, the phase difference information calculation unit 112 estimates the peak position of DFT between each antenna (S13).

Then, the phase difference information calculation unit 112 calculates the inter-antenna phase difference at a specific frequency from the set of frequency components from the signal separation detection unit 111 and the processing result thereof (S14). For example, the phase difference information calculation unit 112 calculates the inter-antenna phase difference at a specific frequency from the peak value and its position detected from the DFT of the inter-antenna product, the estimated peak position, the number of frequency components, and the DFT length. calculate.

Returning to FIG. 3, the direction of arrival estimating section 113 estimates the direction of arrival of the arriving signal.
Since the inter-antenna phase difference calculated by the phase difference information calculation unit 112 is the inter-antenna phase difference at a specific frequency, the arrival direction estimation unit 113 calculates the arrival direction of each incoming signal by calculating the arrival direction of the existing narrowband signal. Estimation is performed using the method used for direction of arrival estimation.

Furthermore, when the direction of arrival estimation unit 113 uses a method of estimating the direction of arrival from a correlation matrix, such as MUSIC (Multiple Signal Classification), the phase difference information calculation unit 112 uses the signal frequency instead of the phase difference between antennas. Similarly to equation (5), the peak component of the DFT of the inter-antenna product of the components may be corrected to the value at frequency k _min Δf as shown in equation (7) below and calculated as an element of the correlation matrix. .

Note that the DFT can be calculated with a small amount of calculation by using a normal FFT (Fast Fourier Transform). However, if the DFT length becomes longer due to zero padding, the amount of calculation will increase. In that case, the amount of calculation can be reduced by using the DFT matrix expressed by the following equation (8), excluding the zero-padded portions, and performing calculations limited to the necessary discrete frequency range.

As described above, according to the first embodiment, the direction of arrival of a signal can be estimated with high accuracy using the method used to estimate the direction of arrival of a narrowband signal.

Embodiment 2.
As shown in FIG. 1, the direction finding device 200 according to the second embodiment includes a plurality of antennas 101, a plurality of filters 102, a high frequency signal generation circuit 103, a plurality of mixers 104, and a plurality of amplifiers. 105, a plurality of A/D converters 106, and a signal processing circuit 210.

The plurality of antennas 101, the plurality of filters 102, the high frequency signal generation circuit 103, the plurality of mixers 104, the plurality of amplifiers 105, and the plurality of A/D converters 106 of the direction finding device 200 according to the second embodiment are the same as those of the embodiment. This is similar to the plurality of antennas 101, the plurality of filters 102, the high frequency signal generation circuit 103, the plurality of mixers 104, the plurality of amplifiers 105, and the plurality of A/D converters 106 of the direction finding device 100 according to No. 1.

Signal processing circuit 210 processes the incoming signal, which is a digital signal from A/D converter 106.
Here, the signal processing circuit 210 estimates the direction of arrival of the signal from the inter-antenna phase difference of the signal received by the antenna array in which the plurality of antennas 101 are arranged at unequal intervals.

FIG. 5 is a block diagram schematically showing the configuration of the signal processing circuit 210.
The signal processing circuit 210 functions as a signal separation detection section 211 , a phase difference information calculation section 212 , a direction of arrival estimation section 113 , and a phase difference information integration section 214 .
The direction of arrival estimation section 113 of the signal processing circuit 210 in the second embodiment is similar to the direction of arrival estimation section 113 of the signal processing circuit 110 in the first embodiment.

The signal separation and detection unit 111 in the first embodiment assigns one signal band to the signal separated and detected from the incoming signal, and calculates one set of frequency components corresponding to the signal band. On the other hand, the signal separation and detection unit 211 in the second embodiment assigns a plurality of signal bands to signals separated and detected in the process of detecting an incoming signal, or integrates a plurality of signals. A set of one or more frequency components corresponding to one or more signal bands is calculated for the signal. The set of frequency components calculated here is given to the phase difference information calculation section 212.

Similar to the phase difference information calculation unit 112 of Embodiment 1, the phase difference information calculation unit 212 calculates a frequency at a specific frequency for one or more signal bands of each signal provided from the signal separation detection unit 211. The phase difference between the antennas or the DFT peak component of the product between the antennas of the signal frequency components is corrected to a value at a specific frequency. Hereinafter, the phase difference between antennas at a specific frequency or the peak component of DFT of the product between antennas of signal frequency components corrected to a value at a specific frequency will be referred to as phase difference information.

When a plurality of signal bands are assigned to each separated and detected signal and a plurality of phase difference information is calculated, the phase difference information integration unit 214 integrates the plurality of phase difference information into one phase difference information. .

A method of calculating one inter-antenna phase difference by integrating inter-antenna phase differences at a plurality of specific frequencies will be described. Here, without loss of generality, the phase difference between the antennas of the signal bands to be integrated is assumed to be two, and the peak position of the DFT estimated by the corrected phase difference between the antennas of the two signal bands a and b. and are shown in the following formulas (9) to (11), respectively.

Then, the inter-antenna phase difference when a specific frequency is k _ref Δf can be calculated by the following equation (12) by weighted averaging using a predetermined weight w _g .

Here, k _ref may be any integer, but k _ref Δf is within a frequency band that includes signal band a, signal band b, and regions between each of signal band a and signal band b. Alternatively, k _ref may be determined to be a value between the respective specific frequency indices k _min of signal band a and signal band b. In this equation (12), the phase difference between the antennas in signal bands a and b is corrected to the phase difference between the antennas at the frequency k _ref Δf, and then the weighted average of the phase differences between the antennas is calculated. By doing so, information on both signal bands can be effectively utilized. The weight of the weighted average may be a value depending on the signal strength or signal bandwidth.

As shown in equation (13) below, the peak component of the DFT of the antenna-to-antenna product of the frequency components of the two signal bands a and signal band b is corrected to the DFT of the antenna-to-antenna product at a specific frequency krefΔf, and then The average polarization angle may be used as the inter-antenna phase difference.

As described above, the phase difference information integration unit 214 converts the phase difference information into phase difference information at a common frequency, and integrates the converted phase difference information.

Note that the direction of arrival estimating section 113 in the second embodiment is similar to the direction of arrival estimating section 113 in the first embodiment, but when using a method of estimating the direction of arrival from a correlation matrix like MUSIC, multiple When the phase difference information is integrated, the peak component of the DFT of the antenna-to-antenna product of the signal components before calculating the declination angle in equation (13) above is corrected, and a matrix whose components are the integrated one is created. It can be used as a correlation matrix.

Part or all of the signal processing circuits 110 and 210 described above, for example, as shown in FIG. It can be configured with a processor 11 such as a central processing unit (Central Processing Unit) or the like. Such a program may be provided through a network, or may be provided recorded on a recording medium. That is, such a program may be provided as a program product, for example.

Further, part or all of the signal processing circuits 110 and 210 may be, for example, a single circuit, a composite circuit, a processor that operates on a program, a parallel processor that operates on a program, as shown in FIG. 6(B), It can also be configured with a processing circuit 12 such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

100, 200 Direction finding device, 101 Antenna, 102 Filter, 103 High frequency signal generation circuit, 104 Mixer, 105 Amplifier, 106 A/D converter, 107 Signal receiver, 110, 210 Signal Processing circuit, 111, 211 signal separation detection 112, 212 phase difference information calculation unit, 113 direction of arrival estimation unit, 214 phase difference information integration unit.

Claims (8)

1. a signal receiving unit comprising an antenna array in which a plurality of antennas are arranged at unequal intervals, and receiving an incoming signal with the antenna array;
   a signal separation and detection unit that separates the incoming signal from the incoming signal if a plurality of incoming signals are included for each of one or more predetermined bands, and detects the incoming signal;
   a phase difference information calculation unit that calculates an inter-antenna phase difference, which is a phase difference between the plurality of antennas, at a specific frequency from the frequency component of each of the detected incoming signals;
   An azimuth finding device comprising: an arrival azimuth estimation unit that estimates the arrival azimuth of each of the arriving signals from the inter-antenna phase difference.
2. The phase difference information calculation unit zero-pads the inter-antenna product so that the length in the frequency direction of the inter-antenna product of the frequency components of each of the incoming signals is a reciprocal ratio of the spacing between the plurality of antennas, and then Detecting or estimating a peak position of an added value obtained by adding calculation results obtained by calculating DFT (Discrete Fourier Transformation) in the frequency direction, and calculating the inter-antenna phase difference at the specific frequency from the peak position. The direction finding device according to claim 1.
3. 3. The phase difference information calculation unit calculates a curve passing through a peak of the added value and a predetermined point around the peak, and estimates the peak position as a real number. direction finding device.
4. The direction finding device according to claim 2 or 3, wherein the phase difference information calculation unit calculates the inter-antenna phase difference using a predetermined DFT matrix.
5. Converting the inter-antenna phase difference calculated for two or more signal bands assigned to one incoming signal to an inter-antenna phase difference at a common frequency, and integrating the converted antenna-to-antenna phase differences. Further equipped with a phase difference information integration section,
   The direction finding device according to any one of claims 1 to 4, wherein the direction of arrival estimating section estimates the direction of arrival of the arriving signal from the integrated phase difference between antennas.
6. The phase difference information calculation unit calculates the inter-antenna phase difference by correcting a peak component of the DFT calculation result of the inter-antenna product of the frequency components of the incoming signal to a value at the specific frequency. The direction finding device according to any one of claims 2 to 4.
7. The phase difference information calculation unit corrects a peak component of a DFT calculation result of an inter-antenna product of frequency components of two or more signal bands assigned to the one incoming signal to a value at the specific frequency,
   further comprising a phase difference information integration unit that converts the peak component of the DFT calculation result of the corrected inter-antenna product into a peak component at a common frequency and integrates the converted peak components,
   The direction finding device according to claim 6, wherein the direction of arrival estimating unit estimates the direction of arrival of each of the arriving signals from the integrated peak components.
8. The incoming signal is received by an antenna array with multiple antennas arranged at unequal intervals,
   If a plurality of incoming signals are included in each of one or more predetermined bands from the incoming signal, the incoming signals are separated, and the incoming signals are detected;
   Calculating an inter-antenna phase difference, which is a phase difference between the plurality of antennas, at a specific frequency from the frequency component of each of the detected incoming signals,
   An azimuth finding method, comprising: estimating the arrival azimuth of each of the arriving signals from the inter-antenna phase difference.

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