JP2937174B2 - Direction finder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direction detecting device for determining the direction of a wave propagating from a single or plural radio wave sources with high accuracy.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional direction finding apparatus. Schmidt, "M
multiple Emitter Location
andSignal Parameter Estim
ation "IEEE Trans. on Anten
na and Propagation, vol. AP
-34, no. 3 is a configuration diagram of a direction detection device based on the content described in March 1986.

FIG. 6 is a diagram showing an operation example of the above-described direction detecting device.

In FIG. 5, reference numeral 2 denotes an antenna platform on which a plurality of antennas directed in the same direction are mounted, 3 denotes a signal processing device C for performing conventional signal processing, 4 denotes a rotation driving device for rotating the antenna platform 2,
5-1, 5-2,..., 5-M are antennas of the same specification for receiving radio waves from radio wave sources, 6-1, 6-2,.
, 6-M are the antennas 5-1, 5-2,.
.. a receiver of the same specification for amplifying and frequency converting radio waves received at 5-M, 7 is a covariance matrix by simultaneously sampling the outputs of the M receivers and performing snapshots a plurality of times , An eigenvalue / eigenvector calculator for calculating an eigenvalue and an eigenvector from the covariance matrix, and 9 a noise portion based on the eigenvalue and the eigenvector obtained by the eigenvalue / eigenvector calculator 8. The noise subspace projection length calculator 10 for projecting the mode vector to the space and calculating the projection length scans the virtual wave source in the space, and the projection length output from the noise subspace projection length calculator 9 is minimized. Projection length minimum value calculator for calculating the azimuth and elevation of the virtual wave source when
Is a mode vector calculator for calculating a mode vector expected by the virtual wave source, and 12 is a control device for instructing the rotation driving device 4 and the mode vector calculator 11 to a predetermined rotation angle.

In FIG. 6, reference numeral 1 denotes an artificial satellite as an example of a radio wave source.

Next, the operation will be described. It is assumed that the number D of the radio sources 1 is smaller than the number M of the antennas 5, and the signals from the respective sources are uncorrelated with each other. Now, M antennas 5
Are input to the receiver 6, where amplification and frequency conversion are performed.

[0007] The outputs of the M receivers 6 are input to a covariance matrix calculator 7. Here, when the outputs of the M receivers 6 are S ₁ , S ₂ ,..., S _M , respectively, the signal vector is represented by Equation 1.

[0008]

(Equation 1)

[0009] If it is assumed that the snapshot is performed P times in obtaining the covariance matrix, the covariance matrix calculator 7 calculates the value shown in Expression 2.

[0010]

(Equation 2)

Equation 2 is the output of the covariance matrix calculator 7.
Here, * represents conjugate or Hermitian conjugate.

The eigenvalue / eigenvector calculator 8 calculates M eigenvalues based on the obtained covariance matrix.
An eigenvector is calculated for each eigenvalue,
These results are input to the noise subspace projection length calculator 9. Lambda ₁ the eigenvalues of the, λ _2, ···, and lambda _M, corresponding eigenvectors of X _1, X _2, ···, is given by equation (3) using X _M Tosureba number 2.

[0013]

(Equation 3)

At this time, the covariance matrix is a positive definite matrix, and all eigenvalues are larger than zero. Assuming that the receiver noises of the receivers 6 are all equal and the standard deviation is σ, Equation 4 holds from the above-described process of D signals being uncorrelated.

[0015]

(Equation 4)

[0016] The eigenvalues λ _1, λ _2, and ···, X ₁ the eigenvector corresponding to λ _D, X _2, ···, and X _D, λ
_{D + 1, λ D + 2} , ···, X D + 1 the eigenvector corresponding to _{λ M, X D + 2,} ···, if _{X M X 1, X 2,} ·
..., the signal subspace spanned by the X _D and X _{D +} 1, X
_{D + 2,} ···, noise subspace spanned by X _M is the orthogonal complement to each other.

Now, when the M antennas 5 are arranged, the mode vector calculator 11 stores the data of the M antenna outputs, that is, the mode vectors, assuming that the wave source exists in the direction of a certain angle. Usually, this angle is over a predetermined range.

However, the mode vector calculator 11 generates a mode vector corresponding to an angle range centered on the azimuth and elevation designated by the controller 12, and generates the azimuth and elevation designated by the controller 12. The antenna platform 2 to the rotary drive 4
Move by

Accordingly, a mode vector at a certain azimuth angle α and a certain elevation angle β is generated by the mode vector calculator 11 and input to the noise subspace projection length calculator 10. On the other hand, the noise subspace projection length calculator 10 projects onto the noise subspace based on the input eigenvalue / eigenvector. If this mode vector is a (α, β), the projection length given by Expression 5 is output from the noise subspace projection length calculator 9.

[0020]

(Equation 5)

In the projection length minimum value calculator 10, the projection length of the mode vector a (α, β) is obtained as a function of α and β, and the α and β values (α ₁ , β
₁ ), (α ₂ , β ₂ ),..., (Α _D , β _D ) are obtained.

(Α ₁ , β ₁ ), (α ₂ , β ₂ ),.
, (Α _D , β _D ) are the angle estimation values in the direction in which D wave sources are present.

[0023]

Since the conventional direction finding apparatus is configured as described above, the aperture of the antenna is increased in order to increase the S / N (signal to noise) ratio of the output of each antenna. At that time, the interval between the antennas is widened, and as a result, a grating lobe is generated, and there is a problem that the wave source exists even in the direction where the wave source does not exist.

The present invention has been made to solve the above problems, and has as its object to suppress this phenomenon.

[0025]

According to a first aspect of the present invention, there is provided a direction finding apparatus comprising: a plurality of antennas; an antenna platform on which the plurality of antennas are mounted so as to point in the same direction; and a predetermined rotation angle command. An instantaneous view invariant rotation driving means for rotating the antenna platform by a predetermined rotation angle while maintaining the pointing direction of the antenna, and generating a plurality of different rotation angle commands, Control means for supplying the respective rotation angle commands; a signal processing device A for processing a signal from the antenna; and a component of the signal processing device A, which is connected to each of the antennas and outputs the output of the antenna. A receiver to which a signal is supplied, a covariance matrix calculator for calculating a covariance matrix from an output of the receiver, An eigenvalue / eigenvector calculator for calculating an eigenvalue and an eigenvector based on a covariance matrix output from a matrix calculator, and the rotation angle command supplied from the control means to the instantaneous visual field invariant rotation driving means, A mode vector calculator for calculating a mode vector for a virtual radio source based on an antenna array; and a noise subspace based on the eigenvalues and eigenvectors output from the eigenvalue / eigenvector calculator, output from the mode vector calculator. A noise subspace projection length calculator for projecting the mode vector to be calculated and calculating the projection length thereof, and the azimuth of the radio wave source when the projection length output from the noise subspace projection length calculator becomes a minimum. From the projection length minimum value calculator for obtaining the angle and the elevation angle, and from the control means, Provided to the field-of-view invariant rotation driving means, corresponding to the respective rotation angle command to rotate the antenna platform, calculate the azimuth angle and the cumulative frequency of the elevation angle of the virtual radio source obtained from the projection length calculator, A cumulative angle detector that outputs an azimuth and an elevation of the virtual radio source corresponding to a predetermined frequency or more.

Further, the direction finder according to the second invention comprises a time correlator between the projection length minimum value calculator of the first invention and the cumulative angle detector, and the covariance matrix calculator of the first invention. The procedure from to the projection length minimum value calculator is repeated under different receiver noises, and the correlation of the position of the virtual radio wave source, which is the output of the minimum value calculator, is obtained.

Further, the direction detecting apparatus according to the third aspect of the present invention includes an instantaneous field-of-view variable rotation driving means instead of the instantaneous field-of-view invariable rotation driving means of the first invention, and an antenna platform such that the directional directions of a plurality of antennas change. Is to be rotated.

Further, the direction finder according to the fourth invention comprises a time correlator between the projection length minimum value calculator and the cumulative angle detector according to the third invention, and the covariance matrix calculator according to the third invention. The procedure from to the minimum projection length calculator is repeated under different receivers, and the correlation of the position of the virtual radio source which is the output of the minimum calculator is obtained.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a block diagram showing a first embodiment of the present invention. In the drawing, reference numeral 2 denotes an antenna platform, and 5-1, 5-2,... , 6-2,... M antennas of the same specification having directivity in the direction of
.., 6-M are the antennas 5-1, 5-2,.
-M a plurality of receivers of the same specification connected to each other, 7
Is a covariance matrix calculator that calculates a covariance matrix from the outputs of the receivers 6-1, 6-2,..., 6-M, and 8 is a covariance matrix output from the covariance matrix calculator 7. An eigenvalue / eigenvector calculator for calculating an eigenvalue and an eigenvector based on the eigenvalue / eigenvector calculator 8
The noise subspace projection length calculator 10 for projecting the mode vector onto the noise subspace based on the eigenvalues and eigenvectors output from the noise subspace and calculating the projection length is output from the noise subspace projection length calculator 9. A projection length minimum value calculator for calculating the azimuth and elevation angle of the radio source when the projection length becomes a minimum, 11 a mode vector calculator for calculating a mode vector, 12 a control device, 13 a signal processing device A, Reference numeral 14 denotes an instantaneous visual field invariable rotation driving device that rotates the antenna platform 2 while keeping the pointing direction of the antenna 5 constant.

Next, the operation will be described. First, the antenna platform 2 is pointed at a predetermined azimuth angle and elevation angle output from the control device 12 using the instantaneous visual field invariant rotation driving device 14. It is assumed that there are D mutually uncorrelated plural radio sources in the instantaneous visual field of the antenna 5 centered on the above-mentioned predetermined azimuth and elevation. The radio waves from the plurality of radio sources are received by the antennas 5-1, 5-2,..., 5-M, and the receivers 6-1, 6-2,.
., 6-M. The receivers 6-1, 6-2,
.., 6-M are amplified and frequency-converted before being input to the covariance matrix calculator 7. The signal input to the covariance matrix calculator 7 is as shown in Expression 1.

The covariance matrix calculator 7 calculates the covariance matrix shown in Expression 2, and calculates the eigenvalue / eigenvector calculator 8
Is input to The eigenvalue / eigenvector calculator 8 calculates M eigenvalues based on the input covariance matrix. After calculating eigenvectors corresponding to the respective eigenvalues, these results are converted into a noise subspace projection length calculator 9. Is input to

[0032] ₁ above the eigenvalues _{λ, λ 2, ···, λ} M
And the corresponding eigenvectors are X ₁ , X ₂ ,..., X _M
Then, it is calculated according to Equation 3.

Since Equation 2 is a positive definite matrix, the eigenvalue λ
₁ , λ ₂ ,..., Λ _M are all greater than zero. Assuming that the standard deviation of the receiver noise of the receiver 6 is σ, Equation 4 holds from the above-described assumption that the D radio sources are uncorrelated with each other.

The eigenvalues λ _1, λ _2, and ···, X ₁ the eigenvector corresponding to λ _D, X _2, ···, and X _D, λ
_{D + 1, λ D + 2} , ···, X D + 1 the eigenvector corresponding to _{λ M, X D + 2,} ···, if _{X M X 1, X 2,} ·
..., the signal subspace spanned by the X _D and X _{D +} 1, X
_{D + 2,} ···, noise subspace spanned by X _M is the orthogonal complement to each other.

In the mode vector calculator 11, the controller 1
An antenna 5 fixed to the antenna platform 2 oriented at a predetermined azimuth and elevation according to an instruction from the antenna 2
A mode vector based on the array of -1, 5-2,..., 5-M is calculated.

For example, as shown in FIG. 7, the direction of the surface of the antenna platform 2 (Z axis) is directed to a predetermined azimuth and elevation by an instruction from the control device 12 to the instantaneous visual field invariable rotation drive device 14. It is assumed that seven antennas 5 are arranged on the surface (on the xy plane) of the antenna platform 2 at intervals d in both the x-axis direction and the y-axis direction.

At this time, the position coordinates of the antenna 5 are given by Equation (6).
It is represented by

[0038]

(Equation 6)

The virtual radio wave source has an azimuth based on the Z axis in FIG.
When it is assumed that the elevation vectors are present in the directions of α and β, respectively, the mode vector calculator 11 calculates a mode vector corresponding to the virtual radio wave source based on an instruction from the control device 12 to the mode vector calculator 11. 7 is obtained.

[0040]

(Equation 7)

In Equation 7, γ is x while fixing the Z axis in FIG.
The angle λ when the antenna 5 is rotated in the y-plane is the wavelength of the virtual radio wave source. FIG. 7 is a diagram when γ = 0, and the initial value of γ is zero.

Now, the noise subspace projection length calculator 9 calculates
A noise subspace is created based on the input eigenvalues and eigenvectors, and the mode vector calculated by the mode vector calculator 11 is projected onto the noise subspace. If this mode vector is b (α, β), the projection length Rb expressed by Expression 8 is output from the noise subspace projection length calculator 9.

[0043]

(Equation 8)

In the projection length minimum value calculator 10, the projection length Rb of the mode vector b (α, β) is obtained as a function of α and β, and the D values of α and β that give the minimum value, (α ₁₁ , Β
₁₁ ), (α ₁₂ , β ₁₂ ),..., (Α _1D , β _1D ) are obtained.

Next, γ = γ ₁ ≠ 0 is set by the control device 12, and the mode vector given by Expression 7 is output from the mode vector calculator 11 to the noise subspace projection length calculator 9.

Further, the control device 12 instructs the instantaneous visual field invariant rotation driving device to the rotation angle γ ₁ , and rotates the antenna platform 2 by the angle γ ₁ in the xy plane while keeping the Z axis fixed.

Again, the processing from the antenna 5 to the minimum projection length calculator 10 is repeated, and the outputs (α ₂₁ , β ₂₁ ), (α ₂₂ , β ₂₂ ),.
(Α _2D , β _2D ) is obtained.

If the above processing is repeated J times, DJ (α, β) combinations are obtained, which are input to the cumulative angle detector 15.

In the cumulative angle detector 15, DJ (α,
The cumulative frequency of β) is calculated, and (α, β) of a predetermined frequency or more
Is output.

For example, the cumulative angle detector 15 outputs the outputs (α _i1 , β _i1 ), (α _i2 , β _i2 ) of the projection length minimum value calculator.
.., (Α _iD , β _iD ) frequency AF is obtained based on Equation 9. Here, i = 1, 2,..., J.

[0051]

(Equation 9)

In Equation 9, α ₀ is the initial value of the azimuth of the cumulative frequency distribution, β ₀ is the initial value of the elevation of the cumulative frequency distribution, Δα is the step size of the azimuth, and Δβ is the step size of the elevation. Also, U (α ₀ + m · Δα, β ₀ + n ·
Δβ) is α ₀ + m · Δα ≦ α <α _{0 in} azimuth
+ (M + 1) · Δα, β ₀ + n in elevation
_{· Δβ ≦ β <β 0 +} (n + 1) · Δβ area represented by contrast, represents a function that gives 1. H (m, n) is U (α ₀
+ M · Δα, β ₀ + n · Δβ), and α ₀ + m
_{· Δα ≦ α <α 0 +} (n + 1) · Δα, β 0 + n · Δβ
≤β <β ₀ + (n + 1) · Δβ represents the cumulative frequency in the region given by: K and L represent the number of azimuths and elevation steps Δα and Δβ, respectively. FIG. 8 is obtained by taking Equation 9 as an example.

In this embodiment, since the cumulative angle detector 15 is provided, the dispersion of the cumulative frequency can be prevented by setting, for example, Δα and Δβ in Equation 9 to appropriate values. , The true value can be easily estimated. In addition, since the instantaneous visual field invariable rotation driving device 14 is provided, the antenna 5
Only by rotating the antenna platform 2 on which the antenna 5 is installed, the array coefficient (array factor) of the array of the antenna 5
Of the antenna 5 can be suppressed without changing the number of antennas 5 and the arrangement of the antennas 5 while keeping the number and arrangement of the antennas 5 constant.
Is unnecessary.

Embodiment 2 FIG. 2 is a block diagram showing a second embodiment of the present invention. In the drawing, reference numeral 16 denotes a process from the covariance matrix calculator 7 to the projection length minimum value calculator 10 for different receiver noises of the receiver 6. This is a time correlator that obtains the correlation of the angle of the virtual radio wave source that is the output of the projection length minimum value calculator 10, and is otherwise the same as FIG.

Next, the operation will be described. The processing from the antenna 5 to the projection length minimum value calculator 10 is the same as in the first embodiment of the present invention.

Now, an output is repeatedly obtained from the projection length minimum value calculator 10 under different receiver noises of the receiver 6, and a correlation of the output is obtained by the time correlator 16.

That is, in the time correlator 16, (α ₁ , β ₁ ), (α ₂ , β ₂ ) obtained from the projection length minimum value calculator 10 under a certain receiver noise of the receiver 6.・, (Α _D ,
β _D ) and (α ₁ , β ₁ ) ′, (α) obtained from the projection length minimum value calculator 10 under another receiver noise of the receiver 6.
₂ , β ₂ ) ', ..., (α _D , β _D )', (α ₁ , β
₁ ) ”, (α ₂ , β ₂ )”,..., (Α _D , β _D ) ”
, And only the coincident angle is set as the output of the time correlator 16.

Next, the cumulative angle detector 15 performs the same processing as that of the first embodiment of the present invention to determine the cumulative frequency of (α, β) for various rotation angles γ, α, β) is output.

Embodiment 3 FIG. 3 is a block diagram showing a third embodiment of the present invention. In the drawing, reference numeral 18 denotes a direction of the surface of the antenna platform 2 (Z axis) in a predetermined direction, and then, based on an instruction from the control device 12. This is an instantaneous field-of-view variation rotation drive device for rotating the surface of the antenna platform 2 so as to be shifted from the predetermined direction, and the other components are the same as those in FIG.

Next, the operation will be described. Control device 12
The antenna platform 2 is directed in a predetermined direction by the instantaneous visual field change rotation driving device 18 based on the instruction from the user.

The mode vector calculator 11 controls the controller 1
The mode vector corresponding to the virtual radio wave source when the antenna platform 2 is directed in the predetermined direction designated by 2 is calculated.

The processing from the antenna 5 to the minimum projection length calculator 10 is the same as in the first embodiment of the present invention. Then, the control device 12 is rotated by the instantaneous visual field variation rotation driving device 18 so that the direction of the surface of the antenna platform 2 is deviated from the initially set direction.

The processing from the antenna 5 to the projection length minimum value calculator 10 is performed again. The cumulative frequency of the angle of the radio wave source obtained by repeating such an operation is obtained by the cumulative angle detector 15, and an angle equal to or greater than a predetermined frequency is output from the cumulative angle detector 15.

Embodiment 4 FIG. 4 is a block diagram showing a fourth embodiment of the present invention. In the drawing, reference numeral 16 denotes a process from the covariance matrix calculator 7 to the projection length minimum value calculator 10 for different receiver noises of the receiver 6. This is a time correlator that calculates the correlation of the angle of the virtual radio wave source, which is the output of the projection length minimum value calculator 10, and is otherwise the same as FIG.

Next, the operation will be described. The processing from the antenna 5 to the minimum projection length calculator 10 is the same as in the third embodiment of the present invention.

The operation of the time correlator 16 is the same as that of the second embodiment of the present invention.

[0067]

According to the first aspect of the present invention, the antenna platform is rotated by the instantaneous visual field invariable rotation driving means based on an instruction from the control means, and a predetermined mode vector is changed based on the instruction from the control means. By calculating with a calculator and obtaining the cumulative frequency of the obtained angle of the wave source with a cumulative angle detector, the influence of the grating lobe caused by the antenna arrangement, that is, the wave source exists even though the wave source does not exist. It is possible to suppress phenomena as if they were doing.

According to the second aspect of the present invention, the use of the time correlator can improve the angle measurement accuracy, and can suppress the influence of the grating lobe caused by the antenna arrangement.

According to the third aspect of the invention, the antenna platform is rotated while changing the directivity of the antenna by the instantaneous visual field change rotation driving means based on the instruction from the control means, and the rotation angle command from the control means is provided. By calculating a predetermined mode vector from the mode vector calculator based on the above, and obtaining the cumulative frequency of the obtained angle of the radio source by the cumulative angle detector, it is possible to suppress the influence of the grating lobe caused by the antenna arrangement. it can.

According to the fourth aspect of the present invention, the use of the time correlator can improve the angle measurement accuracy, and can suppress the influence of the grating lobe caused by the antenna arrangement.

[Brief description of the drawings]

FIG. 1 is a first embodiment of a direction finding apparatus according to the present invention;
FIG.

FIG. 2 is a second embodiment of a direction finding apparatus according to the present invention;
FIG.

FIG. 3 is a third embodiment of the direction finding apparatus according to the present invention;
FIG.

FIG. 4 is a direction finding apparatus according to a fourth embodiment of the present invention;
FIG.

FIG. 5 is a diagram showing a configuration of a conventional direction detection device.

FIG. 6 is a diagram showing an operation example of a conventional direction detection device.

FIG. 7 is a diagram showing an example of an antenna arrangement and a coordinate system of the direction finding apparatus according to the present invention.

FIG. 8 is a diagram showing a cumulative frequency distribution of angle measurement values obtained based on the direction finding device according to the present invention.

[Explanation of symbols]

1 artificial satellite, 2 antenna platform, 3 signal processing device C, 4 rotation drive device, 5 antennas, 6
Receiver, 7 covariance matrix calculator, 8 eigenvalue / eigenvector calculator, 9 noise subspace projection length calculator, 10 projection length minimum value calculator, 11 mode vector calculator, 12
Control device, 13 signal processing device A, 14 instantaneous visual field invariant rotation driving device, 15 cumulative angle detector, 16 time correlator, 17 signal processing device B, 18 instantaneous visual field fluctuation rotation driving device.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01S 3/00-3/86

Claims (4)

(57) [Claims] 1. A plurality of antennas for receiving radio waves from a radio source, an antenna platform on which the plurality of antennas are mounted so as to be directed in the same direction, and a predetermined rotation angle command supplied to the plurality of antennas Instantaneous view invariant rotation drive means for rotating the antenna platform by a predetermined rotation angle while maintaining the directivity direction of the antenna platform, and generating a plurality of different rotation angle commands, and for the instant view invariant rotation drive means, Control means for supplying a rotation angle command; a plurality of receivers connected to each of the plurality of antennas for supplying output signals of the antennas; and a plurality of receivers for calculating a covariance matrix from outputs of the receivers. A variance matrix calculator and an eigenvalue calculating an eigenvalue and an eigenvector based on the covariance matrix output from the covariance matrix calculator. A value / eigenvector calculator, a mode vector calculator for calculating a mode vector based on the rotation angle command supplied from the control means to the instantaneous visual field invariable rotation driving means, and an arrangement of the plurality of antennas, A noise subspace projection length calculator that projects the mode vector output from the mode vector calculator to a noise subspace that is based on the eigenvalue and the eigenvector output from the eigenvalue / eigenvector calculator, and calculates the projection length. A minimum projection length calculator for obtaining an azimuth and an elevation angle of the radio wave source when the projection length output from the noise subspace projection length calculator is minimum; and the instantaneous view invariant rotation from the control unit. Corresponding to the respective rotation angle commands supplied to the driving means to rotate the antenna platform. A cumulative angle detector that calculates the cumulative frequency of the azimuth and elevation of the radio source obtained from the projection length calculator, and outputs the azimuth and elevation of the radio source corresponding to a predetermined cumulative frequency or more. A direction finding device, comprising: 2. A plurality of antennas for receiving radio waves from a radio wave source, an antenna platform on which the plurality of antennas are mounted so as to point in the same direction, a predetermined rotation angle command is supplied, and An instantaneous view invariant rotation driving means for rotating the antenna platform by a predetermined rotation angle while maintaining the direction, and generating a plurality of different rotation angle commands different from each other; Control means for supplying a command, a plurality of receivers connected to each of the plurality of antennas, to which output signals of the antennas are supplied, and a covariance matrix for calculating a covariance matrix from the output of the receiver An eigenvalue / vector for calculating eigenvalues and eigenvectors based on the covariance matrix output from the covariance matrix calculator. A vector calculator, a mode vector calculator for calculating a mode vector based on the rotation angle command supplied from the control means to the instantaneous visual field invariable rotation driving means, and an arrangement of the plurality of antennas, and the eigenvalue / eigenvector. A noise subspace projection length calculator for projecting the mode vector output from the mode vector calculator to a noise subspace based on the eigenvalues and eigenvectors output from the calculator, and calculating the projection length thereof; A projection length minimum value calculator for obtaining an azimuth and an elevation angle of the radio wave source when the projection length output from the subspace projection length calculator is minimum, and the projection length minimum value under different receiver noises A time correlator for calculating the degree of correlation of each of the azimuth angle and the elevation angle of the radio source obtained from the value calculator; and Supplied to the instantaneous visual field invariant rotation driving means, and in response to the respective rotation angle commands for rotating the antenna platform, calculate the azimuth angle and the elevation frequency of the elevation angle of the radio wave source obtained from the time correlator, A direction detecting device, comprising: a cumulative angle detector that outputs an azimuth angle and an elevation angle of the radio wave source corresponding to a predetermined cumulative frequency number or more. 3. A plurality of antennas for receiving radio waves from a radio wave source, an antenna platform on which the plurality of antennas are mounted so as to be directed in the same direction, and a predetermined rotation angle command supplied to the plurality of antennas. Instantaneous field-of-view variation rotation drive means for rotating the antenna platform by a predetermined rotation angle in order to vary the directivity direction of the antenna platform, and generating a plurality of different rotation angle commands, Control means for supplying a rotation angle command; a plurality of receivers connected to each of the plurality of antennas for supplying output signals of the antennas; and a plurality of receivers for calculating a covariance matrix from outputs of the receivers. A variance matrix calculator and eigenvalues for calculating eigenvalues and eigenvectors based on the covariance matrix output from the covariance matrix An eigenvector calculator, a mode vector calculator for calculating a mode vector based on the rotation angle command supplied from the control means to the instantaneous visual field variation rotation driving means, and an arrangement of the plurality of antennas, and the eigenvalue / eigenvector A noise subspace projection length calculator for projecting the mode vector output from the mode vector calculator to a noise subspace based on the eigenvalues and eigenvectors output from the calculator, and calculating the projection length thereof; The projection length minimum calculator for obtaining the azimuth and elevation angle of the radio wave source when the projection length output from the subspace projection length calculator is minimal, and from the control means to the instantaneous visual field fluctuation rotation driving means. In response to the respective rotation angle commands supplied to rotate the antenna platform, A cumulative angle detector for calculating the cumulative frequency of the azimuth and elevation of the radio source obtained from the projection length calculator and outputting the azimuth and elevation of the radio source corresponding to a predetermined cumulative frequency or more. A direction finding device characterized by the above-mentioned. 4. A plurality of antennas for receiving radio waves from a radio wave source, an antenna platform on which the plurality of antennas are mounted so as to point in the same direction, and a predetermined rotation angle command are supplied to the plurality of antennas. Instantaneous field-of-view rotation driving means for rotating the antenna platform by a predetermined angle in order to change the pointing direction of the antenna, and generating a plurality of different rotation angle commands, Control means for supplying an angle command, a plurality of receivers connected to each of the plurality of antennas, to which output signals of the antennas are supplied, and a covariance for calculating a covariance matrix from outputs of the receivers A matrix calculator, and an eigenvalue / fixed vector for calculating an eigenvalue and an eigenvector based on the covariance matrix output from the covariance matrix. A vector vector calculator, a mode vector calculator that calculates a mode vector based on the rotation angle command supplied from the control unit to the instantaneous visual field variation rotation driving unit, and an array of the plurality of antennas,
A noise subspace projection length calculator that projects the mode vector output from the mode vector calculator to a noise subspace that is based on the eigenvalues and eigenvectors output from the eigenvalue / eigenvector calculator and calculates the projection length. And a projection length minimum value calculator for obtaining the azimuth and elevation angle of the radio source when the projection length output from the noise subspace projection length calculator becomes a minimum, under different receiver noises. A time correlator for calculating the degree of correlation of each of the azimuth angle and the elevation angle of the radio wave source obtained from the projection length minimum value calculator, and from the control means, supplied to the instantaneous field-of-view variation rotation driving means, and A cumulative azimuth and elevation of the radio source obtained from the projection length calculator in accordance with the respective rotation angle commands to be rotated. Calculating a frequency direction finding device being characterized in that a cumulative angle detector for outputting azimuth and elevation angle of the radio wave sources corresponding to the predetermined number or more of the cumulative frequency.