JPH11142497A - Wave bearing detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wave bearing detector capable of increasing accuracy by reducing the amount of calculation when the number of incident waves is small. SOLUTION: This wave bearing detector comprises a alley antenna 1; an incident wave estimating means 10 which estimates the number of incident waves; an algorithm selector means 20 which selects an algorithm to obtain a wave input direction according to the number of incident waves; a signal processing device 30 which obtains the input direction from the correlation values of received signals when the number of incident waves is K1 or less; a signal processing device 40 which calculates the correlated matrixes and inter-correlated vectors of the received signals when the number of incident waves is K1 or larger and K2 or less, calculates a load value from the calculated values, and solves an equation with the load value as a factor so as to obtain an input direction; and a signal processing device 50 which calculates the load value with an adaptive filter from the received signals when the number of incident waves is K2 or larger, calculates an antenna pattern from the load value, and detects the null point of the antenna pattern so as to obtain the input direction. Thus, when the number of incident waves is less, accuracy can be increased and the amount of calculation can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio azimuth detecting device for measuring arrival directions of a plurality of incident waves from a signal received by an array antenna.

[0002]

2. Description of the Related Art A conventional radio direction finder will be described with reference to FIG. FIG. 5, for example, ROSchmid
t, “Multiple Emitter Location and Signal Paramete
r Estimation ”, IEEE Trans.Antennas Propag., Vol.A
Conventional music (MUSIC: multiple signal classi) shown in P-34, No. 3, and PP.276-280 (March 1986)
FIG. 3 is a diagram illustrating a radio wave direction detecting device using an algorithm.

[0005] In FIG. 5, reference numeral 1 denotes an array antenna which inputs a received signal to a MUSIC processor 2.

Further, in FIG.
2 shows a processing flow in the processor 2. 3 is a step of inputting the output of the array antenna 1 and calculating a correlation matrix R by obtaining a correlation between the array elements, and 4 is a correlation matrix R
Calculating the eigenvalue λ and eigenvector e of step 5; calculating the eigenvector corresponding to the eigenvalue corresponding to the noise among the eigenvalues obtained in step 4; A step of calculating the reciprocal of the square of the absolute value of the inner value of the inner product of the “steering vector” having the reception phase difference and gain of the antenna 1 and the eigenvector obtained in step 5 as the “azimuth evaluation function P (θ)”, 7 Is the arrival direction θ of the incident wave from the peak appearing in the azimuth evaluation function P (θ) obtained in step 6.
Is the step of estimating.

Next, the operation of the radio wave direction detecting device using the conventional MUSIC algorithm will be described.

[0006] The MUSIC algorithm corresponds to an eigenvalue corresponding to noise of the correlation matrix R of a received signal of the array antenna 1 when a signal of K waves smaller than M is incident on the array antenna 1 having M element antennas. This is a direction finding algorithm that utilizes the property that the eigenvector and the steering vector corresponding to the incident direction of the radio wave are orthogonal.

[0007] element antennas constituting an array antenna 1, an omnidirectional antenna, "x _m" received signal of the m-th array element antenna, the noise "n _m", k-th arrival wave "s _k ”, And the arrival direction is“ θ _k ”. At this time, the “received signal column vector” of the array antenna 1 is represented by the following equation (1).

[0008]

(Equation 1)

A (θ _k ) in the above equation (1) is a steering vector corresponding to the arrival direction θ _k shown in the following equation (2).

[0010]

(Equation 2)

In the above equation (3), g _m (θ _k ) is the “complex gain” of the arrival direction θ _k of the element antenna m, exp
(J (2π / λ) p k · d m) is a complex number representing a reception phase difference. Also, _pk is a “unit vector” in the θ _k direction, d _m
Is the “position vector” of the element antenna m.

In the above equation (1), if the received signal vector on the left side is “X”, the matrix composed of the steering vector is “A”, the incoming signal vector is “S”, and the noise vector is “N”, It can be rewritten as the following equation (4).

[0013]

(Equation 3)

From the above equation (4), the correlation matrix R is given by XX
Required as ^T. The above processing is the processing performed in step 3 of FIG. When the number of array antennas M> the number of arriving signals K, the smallest eigenvalue of the correlation matrix R corresponds to the receiver noise, and the eigenvector E _min and the steering vector a (θ _k ) corresponding to the radio wave arrival direction θ _k are orthogonal. There is nature. Therefore, in the MUSIC algorithm, P (θ) as shown in the following equation (5) is used as the azimuth evaluation function.

[0015]

(Equation 4)

The eigenvalues and eigenvectors of the correlation matrix R are obtained in step 4 of FIG. 5. In step 5 of FIG. 5, the eigenvector E _min corresponding to the smallest eigenvalue λ _min among the obtained M eigenvalues is calculated. The process selected and shown in equation (5) is performed in step 6 of FIG. According to the azimuth evaluation function shown in equation (5), when the eigenvector E _min and the steering vector a (θ) corresponding to the radio wave arrival direction θ are orthogonal, the azimuth evaluation function P (θ) becomes maximum, and this direction θ becomes equal to the radio wave. Is required as the direction of arrival. In step 7 in FIG. 5, the arrival direction of the incident wave is estimated from the peak appearing in the azimuth evaluation function.

In the MUSIC algorithm, it is ideal to find the azimuth evaluation function P (θ) for all directions θ, but in reality, the azimuth evaluation function P (θ) is obtained only for discrete θ columns. Cannot calculate. The number of points in the θ column is defined as i. At this time, (all azimuths to be measured) / i
The azimuth evaluation function can be calculated with the following resolution. The larger the number i of points, the higher the direction of the search. However, there is a disadvantage that the amount of calculation increases accordingly.

[0018]

In the conventional radio azimuth detecting device using the MUSIC algorithm as described above, it is necessary to perform a large amount of processing even when the number of incident waves is small. There was a problem that measurement time was required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide a radio azimuth detecting device capable of reducing the amount of calculation and increasing the accuracy when the number of incident waves is small. I do.

[0020]

A radio azimuth detecting device according to the present invention comprises an array antenna for receiving radio waves, an incident wave number estimating means for estimating an incident wave number from a signal received by the array antenna, and an incident wave number estimating means. A signal processing device switching means for switching a signal processing device that determines an incident direction of a radio wave in accordance with the number of incident waves estimated by the above, and when the number of incident waves is equal to or less than a first constant that is a positive integer, the array antenna A first signal processing device for determining an incident direction of a radio wave based on a correlation value of a received signal; and a first signal processing device in which the number of incident waves is larger than the first constant and is a positive integer and larger than the first constant. If it is smaller than the constant of 2, the correlation matrix and the cross-correlation vector of the received signal of the array antenna are calculated, and the weight value is calculated from the correlation matrix and the cross-correlation vector. A second signal processing device for determining the direction of incidence of radio waves by solving predetermined equations for the coefficient a load value,
When the incident wave number is larger than the second constant, a weight value is calculated by an adaptive filter from a reception signal of the array antenna, an antenna pattern is calculated from the weight value, and a null point of the antenna pattern is detected. And a third signal processing device for determining the incident direction of the radio wave.

Further, in the radio azimuth detecting device according to the present invention, the first signal processing device calculates a correlation value of a reception signal of the two element antennas of the array antenna and calculates a correlation value of the two element antennas from the result. Calculating the reception phase difference to determine the incident direction, the second signal processing device calculates a partial correlation matrix and a cross-correlation vector by performing a correlation process on a part of the received signal of the array antenna, A weight value that minimizes the average power of the signal is calculated from the partial correlation matrix and the cross-correlation vector, and the incident direction is obtained by solving an equation of the same order as the incident wave number using the weight value as a coefficient. The signal processing device, recursively calculates a weight value that minimizes the average power of the signal by an adaptive filter, calculates an antenna pattern when multiplying each element of the array antenna by a weight value, And requests the incident direction of the radio wave by detecting a null point of the antenna pattern.

In the radio azimuth detecting apparatus according to the present invention, the incident wave number estimating means estimates the number of incident waves from the spectrum of a received signal when the incident waves are narrow band signals having different frequencies. .

In the radio azimuth detecting apparatus according to the present invention, the incident wave number estimating means calculates a correlation matrix by performing a correlation process on a signal received by the array antenna, calculates an eigenvalue of the correlation matrix, and calculates an eigenvalue of the correlation matrix. Is used to estimate the number of incident waves from the magnitude of.

Further, the radio azimuth detecting device according to the present invention calculates a correlation matrix by performing correlation processing of an array antenna receiving radio waves and a signal received by the array antenna, calculates an eigenvalue of the correlation matrix, Incident wave number estimating means for estimating the number of incident waves from the magnitude of the eigenvalue, signal processing device switching means for switching a signal processing device for obtaining the incident direction of the radio wave according to the incident wave number estimated by the incident wave number estimating means, When the wave number is equal to or smaller than a first constant that is a positive integer, the correlation value of the reception signals of the two element antennas of the array antenna is calculated, and the reception phase difference of the two element antennas is calculated from the result. A first signal processing device for determining an incident direction, and a second constant, wherein the number of incident waves is larger than the first constant, is a positive integer, and is larger than the first constant. If it is smaller, the second signal processing for calculating a load value that minimizes the average power of the signal from the correlation matrix and solving the equation of the same order as the incident wave number using the load value as a coefficient to obtain the incident direction. The apparatus, if the incident wave number is larger than the second constant, recursively calculates a weight value for minimizing the average power of the signal by an adaptive filter, and multiplies each element of the array antenna by the weight value. And a third signal processing device for calculating an antenna pattern in the case of the above, detecting a null point of the antenna pattern and obtaining an incident direction of a radio wave.

Further, the radio azimuth detecting device according to the present invention calculates an correlation antenna by performing a correlation process on an array antenna receiving radio waves and a signal received by the array antenna, calculates an eigenvalue of the correlation matrix, Incident wave number estimating means for estimating the number of incident waves from the magnitude of the eigenvalue, signal processing device switching means for switching a signal processing device for obtaining the incident direction of the radio wave according to the incident wave number estimated by the incident wave number estimating means, When the wave number is 1, a first signal processing device that calculates an eigenvector corresponding to the largest eigenvalue among the eigenvalues and determines an incident direction using the eigenvector as a steering vector, If the integer is less than a constant greater than 1, a weight value that minimizes the average power of the signal from the correlation matrix Calculate, solve the equation of the same order as the incident wave number with the load value as a coefficient, solve the equation of the incident direction, and, if the incident wave number is larger than the constant, the average power of the signal The weight value to be minimized is recursively calculated by the adaptive filter, the antenna pattern when each element of the array antenna is multiplied by the weight value is calculated, the null point of the antenna pattern is detected, and the incident direction of the radio wave is detected. And a third signal processing device for obtaining

Further, the radio azimuth detecting device according to the present invention calculates a correlation matrix by performing correlation processing of an array antenna for receiving radio waves and a signal received by the array antenna, and calculates an eigenvalue of the correlation matrix. Incident wave number estimating means for estimating the number of incident waves from the magnitude of the eigenvalue, signal processing device switching means for switching a signal processing device for obtaining the incident direction of the radio wave according to the incident wave number estimated by the incident wave number estimating means, When the wave number is 1, a first signal processing device that calculates an eigenvector corresponding to the largest eigenvalue among the eigenvalues and obtains an incident direction using the eigenvector as a steering vector; Obtains an eigenvector corresponding to an eigenvalue corresponding to noise, and calculates a phase characteristic for each direction of the array antenna. Calculating the orientation evaluation function from the steering vector eigenvector having amplitude characteristics as an element, in which a second signal processing device for determining the direction of incidence by detecting the peak of the orientation evaluation function.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 The radio wave direction detecting device according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing a configuration of a radio azimuth detecting device according to Embodiment 1 of the present invention. In the drawings, the same reference numerals indicate the same or corresponding parts.

In FIG. 1, 1 is an array antenna, 10
Is an incident wave number estimating means for estimating the number of incident waves from the received signal of the array antenna 1, and 20 is an algorithm switching means (signal processing device switching means) for switching a radio wave direction finding algorithm according to the number of incident waves obtained by the incident wave number estimating means 10. If 30 is a positive integer K ₁ below there is a incident wave number K (K ≦ K ₁₎ to the signal processor for determining the incident orientation on the principle of the interferometer than the correlation value of the received signal of the array antenna 1 (algorithm 1) , 40 inverse matrix of the incident wave number K may largely positive integer K ₂ smaller than K ₁ (K ₁ <K <K ₂₎ calculating a correlation matrix and cross correlation vector of the received signal of the array antenna 1 in the correlation matrix A signal processing device (algorithm 2) for calculating a load value from the product of the cross-correlation vector and calculating the incident direction from the solution of an equation having the coefficient as a coefficient. If it is ₂ or more (K ₂ ≦
K) is a signal processing device (algorithm 3) that calculates a load value by an adaptive filter and calculates an incident azimuth from null of an antenna pattern calculated from the load value.

Next, the operation of the first embodiment will be described. First, the received signal of the array antenna 1 is input to the incident wave number estimating means 10 to estimate the number of incident waves included in the received signal. As such means, when the incident wave is a narrow band signal having a different frequency, the number of incident waves can be estimated from the spectrum of the received signal.

Next, the algorithm switching means 20 switches the algorithm used for radio wave direction detection according to the number of incident waves obtained by the number of incident waves estimation means 10. The incident wave numbers K ₁ and K that are the boundaries for switching the algorithm
₂ is determined by the calculation amount and accuracy of each algorithm.
Here, as an example, it is assumed that K ₁ = 1 and K ₂ = 5. Also,
It is assumed that each element antenna is omnidirectional and g _m (θ _k ) = 1.

First, when the incident wave number is "1", the algorithm 1 is selected. In the algorithm 1, in the processing step 30, the correlation value of the reception signals of the two element antennas is calculated, and the reception phase difference of the two element antennas is calculated from the calculation result to obtain the incident direction θ.

For example, when the incident wave s ₀ is incident, the correlation values of the received signals of the 0th and 1st antennas of the array antenna 1 are as shown in the following expression (6) from the expressions (1) to (3). .

[0033]

(Equation 5)

The incident direction vector p ₀ can be obtained from the argument of the correlation value (complex number). As described above, when the number of incident waves is one, it is possible to easily know the incident direction without performing many processing steps by the conventional MUSIC algorithm. Further, in the MUSIC algorithm, since the evaluation function is obtained from the inner product of the eigenvector corresponding to noise and the steering vector for each evaluation direction, the incident direction and the evaluation direction do not match, which may degrade the accuracy. Since the incident direction vector p ₀ is obtained directly from (6), it is also effective in terms of accuracy.

Next, the case where the number of incident waves is 2 or more and 4 or less will be described. In this case, the signal processing device 40 based on the algorithm 2 is selected. As in the case of the MUSIC algorithm, a part of the array antenna 1 (for example, 3
A correlation matrix of two element antennas for an element antenna, four elements for a five element array antenna,
And calculate the cross-correlation vector. Array antenna 1
Is the number of elements of M, and the received signal of each element antenna is x
_{0 (t), x 1 (} t), ···, and x _M-1 (t). At this time, the correlation matrix R of x ₁ (t) to x _M-1 (t) and x
₀ (t) and obtaining a cross-correlation vector P of _{x 1 (t) ~x M-} 1 (t) as shown in the following equation (7) and (8) in step 41.

[0036]

(Equation 6)

Next, the signal e calculated by the equation (9)
In step 42 the load w ₁ ~w _M-1 that minimizes the average power of (t) determined by the equation (10).

[0038]

(Equation 7)

Next, in step 43, equation (10)
The K-order equation for u as shown in the following equation (11) having the load obtained as a coefficient as a coefficient is solved.

[0040]

(Equation 8)

The incident angle is obtained from the argument of the solution (complex number) of the above equation (11). Since the incident angle is analytically solved as in the case of one incident wave, it is effective in terms of accuracy and calculation amount. However, the calculation of the inverse matrix in equation (10) and the calculation to solve the K-th order equation in equation (11) involve a large number of incident waves, and becomes extremely difficult as the order increases. Therefore, above a certain order, it is necessary to find a solution by varying parameters.

For the above reason, when the number of incident waves is 5 or more, the signal processing device 50 based on the algorithm 3
Select First, in step 51, recurrently seeking load w ₁ ~w _M-1 that minimizes the average power of the formula (9) by the adaptive filter.

Next, in step 52, equation (12)
The load w is applied to each element of the array antenna 1 as calculated by
Calculating the antenna pattern when multiplied by ₁ ~w _M-1.

[0044]

(Equation 9)

The adaptive filter controls the load so as to minimize the gain in the direction of the incident wave.
Nulls are formed in the incident direction in the pattern calculated in 2). As a result, the incident direction θ of the incident wave can be known.

As described above, in the first embodiment, the direction detection algorithm (signal processing device) is switched according to the number of incident waves. Can detect.

Embodiment 2 Embodiment 2 A radio azimuth detecting device according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 2 is a diagram showing a configuration of a radio wave direction detecting device according to Embodiment 2 of the present invention.

In the second embodiment, of the processing of the first embodiment, the incident wave number estimating means 10 is constituted by the following step processing.

[0049] First, in step 11, and inputs the received signal of the array antenna 1 calculates a correlation matrix R _a as shown in the following equation (13).

[0050]

(Equation 10)

Next, in steps 12 and 13, the eigenvalue of the correlation matrix is calculated, and the number of incident waves is estimated from the magnitude of the eigenvalue. The magnitude of the eigenvalue corresponding to the receiver noise is small and generally has a small variation. Since the eigenvalue corresponding to the incident signal is larger than that corresponding to noise, the number of incident waves can be determined.

When the number of incident waves is determined by such a method, the processing of step 41 in the first embodiment becomes unnecessary. Because the correlation matrix R is the correlation matrix R _a
Of 2 (M-1) row, 2 (M-1) is a matrix composed of the column, the cross-correlation vector P is 2 to the correlation matrix R _a (M-1) row, the first column This is because the matrix is composed of elements. With such a configuration, the same effect as in the first embodiment can be obtained.

Embodiment 3 Embodiment 3 A radio azimuth detecting device according to Embodiment 3 of the present invention will be described with reference to FIG. FIG. 3 is a diagram showing a configuration of a radio wave direction detecting apparatus according to Embodiment 3 of the present invention.

In the third embodiment, when the estimation result of the incident wave number estimating means 10 is 1, the processing of the step 60 replaces the processing of the algorithm 1 (step 30) of the first and second embodiments. (Signal processing device) The direction of the incident wave is detected.

This step 60 (algorithm 1)
When the number of incident waves is one, an eigenvector corresponding to the largest eigenvalue among the eigenvalues obtained in step 12 is obtained. Since this eigenvector is the steering vector a (θ ₀ ) of the incident wave, the incident direction θ can be obtained from this. With such a configuration,
The same effects as in the first and second embodiments can be obtained.

Embodiment 4 Fourth Embodiment A radio azimuth detecting device according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 4 is a diagram showing a configuration of a radio wave direction detecting device according to Embodiment 4 of the present invention.

[0057] In the fourth embodiment, in the algorithm switching means 20, as an algorithm 2 when the incident wave number K is greater than K ₁ (K ₁ <K), the conventional MUSI
Processing similar to the C algorithm is performed in the signal processing device 70. That is, in steps 5 to 7, the eigenvector corresponding to the noise is calculated, and the azimuth evaluation function P (θ) is calculated from the eigenvector and the steering vector of the azimuth to be evaluated as shown in Expression (5). From the peak appearing in this azimuth evaluation function P (θ), the incident direction θ of the incident wave
Ask for. With such a configuration, the same effect as in the first to third embodiments can be obtained.

[0058]

As described above, the radio azimuth detecting device according to the present invention comprises: an array antenna for receiving radio waves;
Incident wave number estimating means for estimating the number of incident waves from the received signal of the array antenna, and a signal processing device switching means for switching a signal processing device that determines the incident direction of a radio wave according to the number of incident waves estimated by the incident wave number estimating means, When the number of incident waves is equal to or less than a first constant that is a positive integer, a first signal processing device that determines an incident direction of a radio wave based on a correlation value of a reception signal of the array antenna; If the value is greater than the first constant, is a positive integer, and is smaller than the second constant having a value larger than the first constant,
A correlation matrix and a cross-correlation vector of the received signal of the array antenna are calculated, a load value is calculated from the correlation matrix and the cross-correlation vector, and a predetermined equation using the load value as a coefficient is solved to obtain an incident direction of a radio wave. A second signal processing device, when the number of incident waves is larger than the second constant, calculate a weight value by an adaptive filter from a reception signal of the array antenna, calculate an antenna pattern from the weight value, Since a third signal processing device for detecting the null point of the antenna pattern to obtain the incident direction of the radio wave is provided, the accuracy can be improved and the amount of calculation can be reduced particularly when the number of incident waves is small. To play.

Further, as described above, the radio azimuth detecting device according to the present invention includes the first signal processing device,
The correlation value of the reception signals of the two element antennas of the array antenna is calculated, and the reception phase difference of the two element antennas is calculated from the calculation result to determine the incident direction. A partial correlation matrix and a cross-correlation vector are calculated by performing a correlation process on a part of the received signal, and a weight value that minimizes the average power of the signal from the partial correlation matrix and the cross-correlation vector is calculated, The incident direction is determined by solving the equation of the same order as the incident wave number having the load value as a coefficient, and the third signal processing device gradually reduces the load value for minimizing the average power of the signal by an adaptive filter. Calculate, calculate the antenna pattern when multiplying each element of the array antenna by a load value, and detect the null point of the antenna pattern to determine the incident direction of the radio wave,
In particular, when the number of incident waves is small, there is an effect that the accuracy can be increased and the amount of calculation can be reduced.

As described above, in the radio azimuth detecting device according to the present invention, when the incident wave number estimating means determines that the number of incident waves is a narrow band signal having a different frequency, the number of incident waves is determined from the spectrum of the received signal. Since the estimation is performed, there is an effect that the accuracy can be improved and the amount of calculation can be reduced particularly when the number of incident waves is small.

In the radio azimuth detecting device according to the present invention, as described above, the incident wave number estimating means calculates a correlation matrix by performing a correlation process on the reception signal of the array antenna, and calculates an eigenvalue of the correlation matrix. Since the calculation is performed and the number of incident waves is estimated from the magnitude of the eigenvalue, there is an effect that the accuracy can be increased and the amount of calculation can be reduced particularly when the number of incident waves is small.

Further, as described above, the radio azimuth detecting device according to the present invention calculates the correlation matrix by performing the correlation processing of the array antenna for receiving the radio wave and the signal received by the array antenna, and calculates the eigenvalue of the correlation matrix. Signal processing device switching means for calculating an incident wave number estimating means for estimating an incident wave number from the magnitude of the eigenvalue, and a signal processing device for obtaining an incident direction of a radio wave according to the incident wave number estimated by the incident wave number estimating means. Means for calculating the correlation value of the reception signals of the two element antennas of the array antenna when the number of incident waves is equal to or less than a first constant that is a positive integer, and calculating the reception position of the two element antennas from the result. A first signal processing apparatus for calculating an incident direction by calculating a phase difference, wherein the number of incident waves is larger than the first constant and is a positive integer and is larger than the first constant. If it is smaller than the second constant of the threshold value, a load value that minimizes the average power of the signal is calculated from the correlation matrix, and an equation of the same order as the incident wave number using the load value as a coefficient is solved to obtain the incident direction. And a second signal processing device for calculating the weighting value for minimizing the average power of the signal when the incident wave number is larger than the second constant. Calculate the antenna pattern when multiplying each element by the load value,
Since a third signal processing device for detecting the null point of the antenna pattern to determine the incident direction of the radio wave is provided, especially when the number of incident waves is small, the accuracy can be improved and the amount of calculation can be reduced. It works.

Further, as described above, the radio azimuth detecting device according to the present invention calculates the correlation matrix by performing correlation processing of an array antenna for receiving radio waves and a signal received by the array antenna, and calculates an eigenvalue of the correlation matrix. Signal processing device switching means for calculating an incident wave number estimating means for estimating an incident wave number from the magnitude of the eigenvalue, and a signal processing device for obtaining an incident direction of a radio wave according to the incident wave number estimated by the incident wave number estimating means. A means for calculating an eigenvector corresponding to the largest eigenvalue among the eigenvalues when the number of incident waves is 1, and a first signal processing device for determining an incident direction using the eigenvector as a steering vector; If it is greater than 1 and less than a constant that is a positive integer and greater than 1, the average power of the signal from the correlation matrix Calculate the load value to minimize the, the second signal processing device to determine the incident direction by solving the equation of the same order as the incident wave number with the load value as a coefficient, when the incident wave number is greater than the constant Calculates the weight value that minimizes the average power of the signal recursively by an adaptive filter, calculates the antenna pattern when each element of the array antenna is multiplied by the weight value, and calculates the null point of the antenna pattern. Since the third signal processing device for detecting the incident direction of the radio wave by detecting the signal is provided, it is possible to increase the accuracy and reduce the amount of calculation, particularly when the number of incident waves is small.

Further, as described above, the radio azimuth detecting device according to the present invention calculates the correlation matrix by performing the correlation processing of the array antenna receiving the radio wave and the signal received by the array antenna, and calculates the eigenvalue of the correlation matrix. Signal processing device switching means for calculating an incident wave number estimating means for estimating an incident wave number from the magnitude of the eigenvalue, and a signal processing device for obtaining an incident direction of a radio wave according to the incident wave number estimated by the incident wave number estimating means. A means for calculating an eigenvector corresponding to the largest eigenvalue among the eigenvalues when the number of incident waves is 1, and a first signal processing device for determining an incident direction using the eigenvector as a steering vector; If it is greater than 1, an eigenvector corresponding to the eigenvalue corresponding to the noise is obtained, and each of the array antennas A second signal processing device for calculating an azimuth evaluation function from a steering vector having phase characteristics and amplitude characteristics with respect to the position as elements and the eigenvector and detecting a peak of the azimuth evaluation function to obtain an incident direction. In particular, when the number of incident waves is small, there is an effect that the accuracy can be increased and the amount of calculation can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a radio azimuth detecting device according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing a configuration of a radio azimuth detecting device according to Embodiment 2 of the present invention.

FIG. 3 is a diagram showing a configuration of a radio azimuth detecting device according to Embodiment 3 of the present invention.

FIG. 4 is a diagram showing a configuration of a radio wave direction detecting apparatus according to Embodiment 4 of the present invention.

FIG. 5 is a diagram showing a configuration of a conventional radio wave direction detecting device.

[Explanation of symbols]

1 array antenna, 10 incident wave number estimation means, 20
Algorithm switching means, 30 a signal processing device using algorithm 1, 40 a signal processing device using algorithm 2, 50 a signal processing device using algorithm 3, 60
Signal processing device according to algorithm 1, 70 Signal processing device according to algorithm 2.

Claims (7)

[Claims] An array antenna for receiving a radio wave, an incident wave number estimating means for estimating an incident wave number from a signal received by the array antenna, and an incident direction of the radio wave according to the incident wave number estimated by the incident wave number estimating means. Signal processing device switching means for switching a signal processing device to be obtained; and, when the number of incident waves is equal to or less than a first constant that is a positive integer, calculating an incident direction of a radio wave based on a correlation value of a reception signal of the array antenna. A first signal processing device; a signal received by the array antenna when the incident wave number is larger than the first constant and smaller than a second constant that is a positive integer and larger than the first constant; Calculating a correlation matrix and a cross-correlation vector, calculating a weight value from the correlation matrix and the cross-correlation vector, solving a predetermined equation using the weight value as a coefficient, Second determining the elevation direction
When the number of incident waves is larger than the second constant, a weight value is calculated from a reception signal of the array antenna by an adaptive filter, an antenna pattern is calculated from the weight value, and the antenna pattern And a third signal processing device for detecting a null point of the radio wave to determine an incident direction of the radio wave. 2. The first signal processing device calculates a correlation value of reception signals of two element antennas of the array antenna, calculates a reception phase difference of the two element antennas from the calculation result, and changes an incident direction. The second signal processing device calculates a partial correlation matrix and a cross-correlation vector by performing a correlation process on a part of the received signal of the array antenna, and calculates the partial correlation matrix and the cross-correlation vector from the partial correlation matrix and the cross-correlation vector. A load value that minimizes the average power of the signal is calculated, and an incident direction is obtained by solving an equation of the same order as the incident wave number using the load value as a coefficient. The third signal processing device calculates an average power of the signal. Is calculated recursively by an adaptive filter, the antenna pattern when each element of the array antenna is multiplied by the load value is calculated, and a null point of the antenna pattern is detected to detect radio waves. Telecommunications orientation detection device of claim 1, wherein the determining the direction of incidence. 3. The radio wave according to claim 1, wherein said incident wave number estimating means estimates the incident wave number from a spectrum of a received signal when the incident wave is a narrow band signal having a different frequency. Direction detection device. 4. The incident wave number estimating means calculates a correlation matrix by performing a correlation process on a reception signal of the array antenna,
The eigenvalue of the correlation matrix is calculated, and the number of incident waves is estimated from the magnitude of the eigenvalue.
Radio azimuth detection device as described. 5. An array antenna for receiving a radio wave, and a correlation matrix is calculated by performing a correlation process on a signal received by the array antenna, an eigenvalue of the correlation matrix is calculated, and the number of incident waves is estimated from the magnitude of the eigenvalue. An incident wave number estimating unit; a signal processing device switching unit that switches a signal processing device that obtains an incident direction of a radio wave according to the incident wave number estimated by the incident wave number estimating unit; and a first in which the incident wave number is a positive integer. If not greater than a constant, a first signal processing apparatus for calculating the correlation value of the received signals of the two element antennas of the array antenna and calculating the reception phase difference between the two element antennas from the result to determine the incident direction And if the incident wave number is greater than the first constant, is a positive integer and is smaller than a second constant having a value greater than the first constant, a signal from the correlation matrix Calculates a load value that minimizes the average power, the second to determine the incident direction by solving an equation of the same order as the incident wave number and coefficient of the load value
When the number of incident waves is larger than the second constant, a weight value for minimizing the average power of the signal is recursively calculated by an adaptive filter, and a weight is applied to each element of the array antenna. A third signal processing device that calculates an antenna pattern when multiplied by a value, detects a null point of the antenna pattern, and obtains an incident direction of the radio wave. 6. An array antenna for receiving a radio wave, a correlation matrix is calculated by performing a correlation process on a signal received by the array antenna, an eigenvalue of the correlation matrix is calculated, and the number of incident waves is estimated from the magnitude of the eigenvalue. An incident wave number estimating unit; a signal processing device switching unit that switches a signal processing device that determines an incident direction of a radio wave according to the incident wave number estimated by the incident wave number estimating unit; and the eigenvalue when the incident wave number is 1. A first signal processing device that calculates an eigenvector corresponding to the largest eigenvalue and determines the incident direction using the eigenvector as a steering vector; and the incident wave number is greater than 1 and is a positive integer greater than 1. If the value is smaller than the constant, a load value for minimizing the average power of the signal is calculated from the correlation matrix, and the input value having the load value as a coefficient is calculated. A second signal processing device for solving the equation of the same order as the wave number to obtain the incident direction; and when the incident wave number is larger than the constant, a load value for minimizing the average power of the signal is gradually reduced by an adaptive filter. And a third signal processing device for calculating an antenna pattern when each element of the array antenna is multiplied by a load value, and detecting a null point of the antenna pattern to obtain an incident direction of a radio wave. A radio azimuth detecting device characterized by the above-mentioned. 7. An array antenna for receiving a radio wave, and a correlation matrix is calculated by performing a correlation process on a signal received by the array antenna, an eigenvalue of the correlation matrix is calculated, and the number of incident waves is estimated from the magnitude of the eigenvalue. An incident wave number estimating unit; a signal processing device switching unit that switches a signal processing device that determines an incident direction of a radio wave according to the incident wave number estimated by the incident wave number estimating unit; and the eigenvalue when the incident wave number is 1. A first signal processing device that calculates an eigenvector corresponding to the largest eigenvalue and determines an incident direction using the eigenvector as a steering vector, and, when the number of incident waves is greater than 1, corresponds to an eigenvalue corresponding to noise. An eigenvector is obtained, and the steering having the phase characteristic and the amplitude characteristic for each direction of the array antenna as an element. Calculating the orientation evaluation function from vector and the eigenvector, wave direction detection apparatus characterized by comprising a second signal processing apparatus detect and determine the direction of incidence of the peak of the orientation evaluation function.