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WO2019030857A1 - Direction-of-arrival estimation device - Google Patents

Direction-of-arrival estimation device Download PDF

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Publication number
WO2019030857A1
WO2019030857A1 PCT/JP2017/028935 JP2017028935W WO2019030857A1 WO 2019030857 A1 WO2019030857 A1 WO 2019030857A1 JP 2017028935 W JP2017028935 W JP 2017028935W WO 2019030857 A1 WO2019030857 A1 WO 2019030857A1
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Prior art keywords
generation unit
calculation unit
monopulse
direction estimation
arrival direction
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PCT/JP2017/028935
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French (fr)
Japanese (ja)
Inventor
浩文 福島
龍平 高橋
信弘 鈴木
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三菱電機株式会社
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Application filed by 三菱電機株式会社 filed Critical 三菱電機株式会社
Priority to PCT/JP2017/028935 priority Critical patent/WO2019030857A1/en
Priority to JP2019531840A priority patent/JP6625285B2/en
Publication of WO2019030857A1 publication Critical patent/WO2019030857A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
    • G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
    • G01S3/14—Systems for determining direction or deviation from predetermined direction
    • G01S3/46—Systems for determining direction or deviation from predetermined direction using antennas spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems

Definitions

  • the present invention relates to a technique for estimating the direction of arrival (DOA) of radio waves, and more particularly to a technique for estimating the arrival direction of incoming waves based on correlation information of the incoming waves using an array antenna. .
  • DOA direction of arrival
  • Non-Patent Document 1 a technique called adaptive monopulse in which a monopulse beam is formed using an adaptive weight and suppression of unnecessary waves and angle measurement are simultaneously performed.
  • Non-Patent Document 1 proposes a technique (hereinafter referred to as “Fante method”) for correcting the distortion of the discriminator curve using three constraint conditions.
  • Finante method proposes a technique for correcting the distortion of the discriminator curve using three constraint conditions.
  • the freedom of the antenna is consumed due to the three constraint conditions.
  • An arrival direction estimation apparatus is an arrival direction estimation apparatus that executes an adaptive monopulse to calculate an estimated value of an arrival angle of an incoming radio wave, and includes M (M is an integer of 2 or more) antenna elements. Calculating the M ⁇ weights respectively corresponding to the M received signals using the correlation matrix generation unit that generates a correlation matrix based on the M received signals respectively obtained from the output of and the correlation matrix Calculating the M ⁇ weights respectively corresponding to the M received signals by executing the power minimizing method using the ⁇ weight calculating unit and the M ⁇ ⁇ ⁇ ⁇ weights and the two constraint conditions A weight calculation unit and the M pieces of ⁇ ⁇ ⁇ ⁇ weights are respectively weighted to the M received signals to generate M first weighting signals, and ⁇ be based on the M first weighting signals.
  • ⁇ beam generation unit for generating M, and M second weighting signals are generated by weighting the M reception signals by the M ⁇ weights, respectively, and the M second weighting signals are generated.
  • a ratio calculation unit for calculating a ratio between the ⁇ ⁇ ⁇ beam generated by the ⁇ beam generator and the ⁇ ⁇ ⁇ beam generated by the ⁇ ⁇ ⁇ beam generator as a monopulse ratio.
  • a ratio calculation unit for calculating a ratio between the ⁇ ⁇ ⁇ beam generated by the ⁇ beam generator and the ⁇ ⁇ ⁇ beam generated by the ⁇ ⁇ ⁇ beam generator as a monopulse ratio.
  • a ratio calculation unit for calculating a ratio between the ⁇ ⁇ ⁇ beam generated by the ⁇ beam generator and the ⁇ ⁇ ⁇ beam generated by the ⁇ ⁇ ⁇ beam generator as a monopulse ratio.
  • a ratio calculation unit for calculating a ratio between the ⁇ ⁇ ⁇ beam generated by the ⁇ beam generator and the ⁇ ⁇ ⁇ beam generated by the ⁇ ⁇ ⁇ beam generator as a monopulse ratio. It is characterized by having.
  • the ⁇ weight for generating the ⁇ beam is calculated by executing the power minimization method using the ⁇ ⁇ ⁇ ⁇ weight and the two constraint conditions. Distortion can be corrected. Therefore, it is possible to realize high angle measurement accuracy with low calculation load. It is also possible to suppress excessive consumption of antenna freedom.
  • FIG. 1 is a block diagram schematically showing an example of a hardware configuration for realizing an arrival direction estimation apparatus according to a first embodiment. It is a block diagram which shows schematic structure of the arrival direction estimation apparatus which is Embodiment 2 which concerns on this invention.
  • FIG. 16 is a flowchart schematically showing an example of the procedure of the direction of arrival estimation method according to Embodiment 2.
  • FIG. 1 is a block diagram showing a schematic configuration of an arrival direction estimation apparatus 1 according to a first embodiment of the present invention.
  • the arrival direction estimation apparatus 1 has a function of executing an adaptive monopulse to calculate an estimated value of an arrival angle of an incoming radio wave.
  • Adaptive monopulse refers to monopulse angle measurement using adaptive weights for null formation in the direction of unwanted waves.
  • the arrival direction estimation apparatus 1 comprises an array antenna 20 consisting of M (M is an integer of 3 or more) antenna elements 20 1 , 20 2 ,.
  • a receiving unit 21 for converting the x M (t n), the received signals x 1 ( t n) ⁇ x M (t n) from the sigma-beam generating unit 41 for generating a sigma beam P sigma, the received signal x 1 (t n) ⁇ x M (t n) ⁇ beam to generate a delta beam P delta from A generator 42, a monopulse ratio calculation unit 43 that calculates a ratio R between ⁇ beam P ⁇ and ⁇ beam P ⁇ as a monopulse ratio, and estimation of an incoming radio wave by comparing a reference discriminator curve and a monopulse ratio R Angle calculation unit 44 for calculating a value, And a data output unit 45 outputs the estimated data MD indicating the putative value to an external device.
  • the arrival direction estimation apparatus 1 calculates ⁇ weight vector W ⁇ and ⁇ weight vector W ⁇ as adaptive weights from the received signals x 1 (t n ) to x M (t n ), and these ⁇ ⁇ ⁇ weight vectors W ⁇ ⁇ and
  • the adaptive weight calculation unit 30 is provided to supply the ⁇ weight vector W ⁇ to the ⁇ ⁇ ⁇ beam generation unit 41 and the ⁇ beam generation unit 42, respectively.
  • Source Tgt shown in FIG. 1 is a signal source is a target that exists in the angular direction of theta t with respect to the center of the array antenna 20 (the front direction).
  • the radiation source U 1, ..., U k ( k is an integer of 2 or more) is unnecessary wave source that emits an unknown signal.
  • the radiation sources U 1 ,..., U k are present at angular directions ⁇ 1 ,..., ⁇ k with respect to the center (front direction) of the array antenna 20.
  • unnecessary waves for example, multipath waves, sea clutter, or disturbance waves generated due to a structure or the like are assumed.
  • the receiving unit 21 includes receivers (Rx) 21 1 ,..., 21 M that perform analog signal processing on RF (high frequency) outputs of the antenna elements 20 1 ,..., 20 M , and these receivers (Rx) 21 1. , ..., 21 M each received signal x 1 in digital form the analog output of the (t n), ..., a / D converter for converting the x M (t n) (ADC ) 22 1, ..., and 22 M It is comprised including.
  • Each receiver 21 m performs various signal processing such as amplification processing, band pass processing (filter processing) and frequency conversion processing on the RF output of the corresponding antenna element 20 m to generate an analog signal. This analog signal is a complex signal having in-phase and quadrature components.
  • Each A / D converter 22 m converts an analog signal input from the corresponding receiver 21 m into a reception signal x m (t n ) which is a complex baseband signal in digital form.
  • the adaptive weight calculation unit 30 includes a correlation matrix generation unit 31, a parameter setting unit 32, a ⁇ weight calculation unit 33, and a ⁇ weight calculation unit 34.
  • the correlation matrix generation unit 31 generates a correlation matrix R xx based on the reception signals x 1 (t n ) to x M (t n ), and the inverse matrix R xx ⁇ 1 with respect to the correlation matrix R xx is a ⁇ ⁇ ⁇ ⁇ weight calculation unit 33
  • the correlation matrix R xx and the received signal vector x (t n ) can be expressed by the following equations (1) and (1a) Given.
  • n is a subscript indicating a sampling time number, and is an integer in the range of 1 to N.
  • the superscript “H” attached to the received signal vector x (t n ) in the above equation (1) indicates the complex conjugate transposition (hermite transposition), and the superscript “in the above equation (1a) "T” indicates transposition.
  • the correlation matrix generation unit 31 can calculate, for example, the inverse matrix R xx -1 using Cholesky decomposition.
  • the ⁇ ⁇ ⁇ ⁇ weight calculation unit 33 uses the parameter setting values supplied from the parameter setting unit 32 and the inverse matrix R xx ⁇ 1 to generate an M-row, 1-column ⁇ weight vector W ⁇ ⁇ consisting of M vector elements ( ⁇ weights). Can be calculated.
  • sigma weight calculator 33 it is possible to calculate the sigma weight vector W sigma running power minimization method such as DCMP (Directionally Constrained Minimization of Power) method.
  • the parameter setting unit 32 sends, to the ⁇ ⁇ ⁇ ⁇ weight calculation unit 33, the parameter setting values ⁇ and C ( ⁇ t ) including the information ⁇ t of the target direction obtained by processing such as tracking processing and the response value h expected of the target direction. Supply.
  • the ⁇ ⁇ ⁇ ⁇ weight vector W ⁇ is given by, for example, the following equation (2).
  • Equation (2) C ( ⁇ t ) is a steering vector (constraint vector) in a desired direction, and ⁇ is a constant.
  • the constant ⁇ is expressed by the following equation (3).
  • the ⁇ weight calculation unit 33 uses the ⁇ ⁇ weight vector W ⁇ ⁇ using the equation to which the diagonal load is applied using the coefficient ⁇ and the unit matrix I as shown in the following equation (4). May be calculated.
  • the ⁇ weight calculation unit 34 executes the power minimization method using the ⁇ ⁇ ⁇ ⁇ weight vector W ⁇ ⁇ and two constraint conditions to obtain received signals x 1 (t n ) to x M (t n ) respectively.
  • a corresponding ⁇ weight vector W ⁇ consisting of ⁇ weights can be calculated.
  • the ⁇ weight vector W ⁇ is an M-by-1 vector consisting of M vector elements ( ⁇ weights).
  • the ⁇ weight calculation unit 34 supplies the calculated ⁇ weight vector W ⁇ to the ⁇ beam generation unit 42.
  • the ⁇ weight calculation unit 34 derives an optimum ⁇ weight vector W ⁇ such that distortion does not occur in the discriminator curve when the adaptive mono pulse is performed.
  • the processing content of the ⁇ weight calculation unit 34 will be described in detail.
  • the discriminator curve obtained by ordinary monopulse angle measurement before adaptive monopulse execution is formulated.
  • normal monopulse angle measurement as shown in FIG. 2, when the angle indicating the center direction of the antenna is ⁇ 0 , the sum (sum signal) of beams 50R and 50L obtained by dividing the array antenna 20 into two A certain ⁇ beam and a ⁇ beam which is a difference (difference signal) between the beams 50R and 50L are calculated.
  • the ratio between the ⁇ beam and the ⁇ beam is defined as a discreet curve.
  • the beams 50R and 50L can be expressed as the following equations (5) and (6), respectively.
  • a ( ⁇ ) is the array manifold (vector) of the array antenna 20 used, and ⁇ is the center of each of the beams B right ( ⁇ ) and B left ( ⁇ ) It is a squint angle from the direction.
  • a first-order partial differential of the array manifold a ( ⁇ ) with respect to the angle ⁇ is expressed by the following equation (6a).
  • the ⁇ beam and the ⁇ beam for monopulse angle measurement can be expressed as the following equations (7) and (8), respectively.
  • T diff is a diagonal matrix and can be expressed, for example, as in the following equation (12).
  • diag (X) is a diagonal matrix having M vector elements of vector X as diagonal elements.
  • M is an even number
  • the number of diagonal components “1” in the diagonal matrix T diff is M / 2
  • the number of diagonal components “ ⁇ 1” is M / 2.
  • j represents an imaginary unit, r 1, ..., r M, the antenna elements 20 1, ..., represents the position vector of 20 M.
  • the first-order partial differential with respect to the angle ⁇ of P ( ⁇ ) is a partial differential with respect to the angle of the direction vector of the desired direction, and is expressed by the following equation (13a).
  • equation (13) When equation (13) is used, the above equation (11) can be expressed by the following equation (14).
  • FIG. 3 shows the distribution of the error voltage obtained at the time of execution (non-suppression processing) of normal monopulse angle measurement before the adaptive mono-pulse execution, and the error voltage obtained at the time of adaptive mono-pulse execution (suppression processing) based on equation (10) It is a graph showing distribution of.
  • the horizontal axis indicates the angle in the direction of arrival, and the vertical axis indicates the error voltage (that is, the value of the discriminator curve).
  • distortion ⁇ occurs in the discriminator curve when the adaptive mono pulse is executed, and a bias error occurs in the angle measurement value with respect to the discriminator curve before the adaptive mono pulse is executed.
  • the first constraint condition is the discriminator curve (first discriminator curve) r before ( ⁇ ) obtained by executing normal monopulse angle measurement without executing the adaptive monopulse, and the discriminator curve obtained by executing the adaptive monopulse.
  • the ⁇ ⁇ ⁇ beam generation unit 41 performs weighted addition using the ⁇ ⁇ ⁇ ⁇ weight vector W ⁇ ⁇ ⁇ according to the following equation (22) to calculate the response value P ⁇ of the ⁇ ⁇ ⁇ beam This response value P ⁇ is output to the monopulse ratio calculation unit 43.
  • the ⁇ beam generation unit 42 can calculate the response value P ⁇ -Pro of the ⁇ beam by executing weighted addition using the ⁇ weight vector W ⁇ -pro according to the following equation (23).
  • the response value P ⁇ -Pro is output to the monopulse ratio calculator 43.
  • Monopulse ratio calculator 43 sigma a ratio between the response value P sigma response values P sigma and sigma beam of the beam is calculated as the monopulse ratio R, and outputs the calculation result to the angle measuring arithmetic unit 44.
  • the monopulse ratio R can be expressed, for example, by the following equation (24).
  • the angle measurement calculation unit 44 calculates an estimated value (angle measurement value) of the arrival angle by comparing the reference discriminator curve r before ( ⁇ ) held in the internal memory 44 a with the value of the monopulse ratio R. Can.
  • an error occurs in the estimated value because the calculated monopulse ratio is present on the distorted discriminator.
  • a large distortion does not occur in the discriminator curve when the adaptive mono pulse is performed, so that it is possible to calculate the angle measurement value with higher accuracy than the prior art.
  • FIG. 5 shows the distribution of four types of error voltages (discs using a square array of elements in which 64 antenna elements are two-dimensionally arranged along the X-axis direction and the Y-axis direction as shown in FIG. It is a graph which shows the result of having calculated recurve.
  • ⁇ indicates a wavelength (unit: meter).
  • the separation angle between the target direction and the unwanted wave is about 1 ⁇ 4 of the beam width, and the unwanted wave power is 20 dB higher than the desired power. Further, in the graph of FIG.
  • the solid line indicates the discriminator curve obtained by the non-suppression process (the above-mentioned normal monopulse angle measurement), and the circle symbol is obtained by the example of the adaptive monopulse according to the present embodiment.
  • the distortion of the discriminator curve is corrected even under severe conditions where high power unwanted waves are present in the main beam. Furthermore, it can be confirmed that the effect of the correction obtained in the example is higher than the effect of the correction obtained by the Fante method using three constraint conditions.
  • FIG. 6 is a flowchart schematically showing an example of a procedure of an arrival direction estimation process according to the first embodiment.
  • the correlation matrix generation unit 31 obtains the reception signal vector x (t n ) output from the reception unit 21 (step ST20), and as described above, the correlation matrix is obtained based on the reception signal vector x (t n ).
  • R xx is calculated (step ST22).
  • the correlation matrix generation unit 31 supplies the inverse matrix R xx ⁇ 1 to the generated correlation matrix R xx to the ⁇ ⁇ ⁇ ⁇ weight calculation unit 33.
  • the ⁇ weight calculation unit 33 acquires the parameter setting value from the parameter setting unit 32 as described above (step ST24), and the ⁇ weight vector W ⁇ is obtained based on the parameter setting value and the inverse matrix R xx ⁇ 1. It calculates (step ST25).
  • the ⁇ ⁇ ⁇ ⁇ weight calculating unit 33 supplies the calculated ⁇ ⁇ ⁇ ⁇ weight vector W ⁇ to the ⁇ weight calculating unit 34 and the ⁇ ⁇ ⁇ beam generating unit 41.
  • the ⁇ weight calculation unit 34 calculates the ⁇ weight vector W ⁇ by executing the power minimization method using the ⁇ ⁇ ⁇ ⁇ weight vector W ⁇ ⁇ and the two constraint conditions as described above (step ST26).
  • the ⁇ weight calculation unit 34 supplies the calculated ⁇ weight vector W ⁇ to the ⁇ beam generation unit 42.
  • sigma beam generating unit 41 uses the sigma weight vector W sigma calculates the sigma beam response value (step ST27), delta beam generating portion 42, a delta beam response value using the delta weight vector W delta It calculates (step ST28).
  • the execution order of steps ST27 and ST28 is not particularly limited.
  • sigma a ratio between the response value P sigma response values P sigma and sigma beam of the beam is calculated as the monopulse ratio R, and outputs the calculation result to the angle measuring operation section 44 (step ST29).
  • the angle measurement calculation unit 44 compares the reference discriminator curve r before ( ⁇ ) with the value of the monopulse ratio R to calculate an estimated value (angle measurement value) of the arrival angle (step ST30).
  • the data output unit 45 outputs the estimated data MD indicating the estimated value to the external device (step ST31).
  • the ⁇ beam generation unit 41, the ⁇ beam generation unit 42, the monopulse ratio calculation unit 43, the angle measurement calculation unit 44, and the adaptive weight calculation unit 30 are, for example, ASIC (Application Specific Integrated) It may be realized by a processor including an LSI (Large Scale Integrated circuit) such as a Circuit) or an FPGA (Field-Programmable Gate Array).
  • the ⁇ beam generation unit 41, the ⁇ beam generation unit 42, the monopulse ratio calculation unit 43, the angle measurement calculation unit 44, and the adaptive weight calculation unit 30 may be a central processing unit (CPU) or a graphics processing unit (GPU) that executes a computer program. And may be realized by one or more processors.
  • FIG. 7 is a block diagram showing an example of a hardware configuration for realizing the functions of the ⁇ beam generation unit 41, the ⁇ beam generation unit 42, the monopulse ratio calculation unit 43, the angle calculation unit 44 and the adaptive weight calculation unit 30.
  • a signal processing device 70 shown in FIG. 7 includes a processor 71 formed of a semiconductor integrated circuit, a memory 72, an input interface unit 73, an output interface unit 74, and a signal path 75.
  • the signal path 75 is a bus for mutually connecting the processor 71, the memory 72, the input interface unit 73, and the output interface unit 74.
  • the input interface 73 is a circuit having a function of acquiring the reception data RS indicating the reception signal vector x (t n ) input from the reception unit 21 and transferring the reception data RS to the processor 71 via the signal path 75. is there.
  • the processor 71 is connected to an external device such as a display device via the signal path 75 and the output interface 74.
  • the memory 72 is, for example, a program memory for storing various programs for realizing the signal processing function of the arrival direction estimation apparatus 1 of the present embodiment, a work memory used when the processor 71 performs signal processing, And a memory in which data used in the signal processing is expanded.
  • a plurality of semiconductor memories such as a ROM (Read Only Memory) and an SDRAM (Synchronous Dynamic Random Access Memory) may be used.
  • the single processor 71 is used, but the present invention is not limited to this.
  • the signal processing function of the arrival direction estimation apparatus 1 may be realized using a plurality of processors operating in cooperation with each other.
  • any of the ⁇ ⁇ ⁇ beam generation unit 41, the ⁇ beam generation unit 42, the monopulse ratio calculation unit 43, the angle measurement calculation unit 44, and the adaptive weight calculation unit 30 may be configured by dedicated hardware.
  • FIG. 8 is a block diagram showing a schematic configuration of the arrival direction estimation apparatus 2 according to the second embodiment of the present invention.
  • the arrival direction estimation apparatus 1 of the first embodiment an adaptive array is used, and suppression of unnecessary waves is performed in a spatially local region.
  • the adaptive weights W ⁇ and W ⁇ are calculated, the direction in which the null is formed due to the environmental fluctuation such as the oscillation of the airframe equipped with the arrival direction estimation device or the movement of the target. It is possible that the unnecessary wave source may be removed from the In such a case, there is a possibility that the suppression performance is lowered and the angle measurement accuracy is lowered.
  • the arrival direction estimation apparatus 2 of the present embodiment can calculate an adaptive weight capable of forming a broad null.
  • the configuration of the arrival direction estimation apparatus 2 of the present embodiment is that of the first embodiment except that it has the adaptive weight calculation unit 30A of FIG. 8 instead of the adaptive weight calculation unit 30 (FIG. 1) of the above embodiment.
  • the configuration is the same as that of the arrival direction estimation apparatus 1 of FIG.
  • the adaptive weight calculation unit 30A includes a correlation matrix generation unit 31A, a parameter setting unit 32, a ⁇ ⁇ ⁇ ⁇ weight calculation unit 33, a ⁇ weight calculation unit 34, a null width adjustment parameter setting unit 35, and a taper matrix.
  • a generation unit 36 is provided.
  • the configuration of parameter setting unit 32, ⁇ weight calculation unit 33 and ⁇ weight calculation unit 34 in the present embodiment is the same as the configuration of parameter setting unit 32, ⁇ weight calculation unit 33 and ⁇ weight calculation unit 34 in the first embodiment. It is the same.
  • the parameter setting unit for null width adjustment supplies the parameter set values u ⁇ and u ⁇ necessary for generating the taper matrix T for null width control to the taper matrix generation unit.
  • the taper matrix generation unit 36 generates a taper matrix T using the parameter setting values u ⁇ and u ⁇ . The method of generating the taper matrix T will be described in detail below.
  • the signal vector x u (t) of the unwanted wave in this case can be expressed as in the following equation (25), where a u is the steering vector in the unwanted wave direction and u (t) is the complex amplitude of the unwanted wave.
  • the m th row and n th column component of the correlation matrix related to the unnecessary wave can be expressed as in the following equation (26).
  • E [X] is the ensemble average of X
  • P u is the power of the unnecessary wave
  • ⁇ is the wavelength of the unnecessary wave
  • r m is the position vector of the mth antenna element 20 m
  • r n is L ( ⁇ u , ⁇ u ) represents a direction vector in which the unwanted wave arrives, for example, the position vector of the n-th antenna element 20 n .
  • Equation (27) can be expanded by a first-order approximation as in the following Equation (28).
  • the correlation matrix R u-broad in the case where the unnecessary wave has a spatial spread according to the equation (29) is an element product (Hadamard product) of the matrix R u and the taper matrix T as shown in the following equation (30) Can be represented by
  • taper matrix T can be expressed as the following equation (31).
  • taper matrix generation unit 36 sets the setting values of parameters u ⁇ and u ⁇ output from null width adjustment parameter setting unit 13 according to the above equation (32), and position vectors r of antenna elements 20 m and 20 n.
  • the taper matrix T for null width control can be determined using m 1 and r n .
  • the arbitrary array arrangement of the antenna elements 20 1 to 20 M and the fact that the null width can be adjusted in the azimuth and elevation directions is one of the features of this embodiment.
  • the taper matrix generation unit 36 supplies the calculated taper matrix T to the correlation matrix generation unit 31A.
  • the correlation matrix generation unit 31A generates the correlation matrix R brd (element product of the correlation matrix R xx and the taper matrix T) corrected by applying the taper matrix T to the correlation matrix R xx as shown in the following equation (33). Can be generated.
  • the correlation matrix generation unit 31A supplies the inverse matrix R brd -1 for the corrected correlation matrix R brd to the ⁇ ⁇ ⁇ ⁇ weight calculation unit 33.
  • the ⁇ weight calculation unit 33 can calculate the ⁇ ⁇ ⁇ ⁇ weight W ⁇ by executing the power minimization method using the inverse matrix R brd ⁇ 1 as in the first embodiment.
  • FIG. 9 is a flowchart schematically showing an example of a procedure of an arrival direction estimation process according to the second embodiment.
  • the procedure of the flowchart of FIG. 9 is the same as the procedure of the flowchart of FIG. 6 except that steps ST21 and ST23 are included.
  • step ST21 the taper matrix generation unit 36 sets the set values of the parameters u ⁇ and u ⁇ and the antenna elements 20 m and 20 n supplied from the null width adjustment parameter setting unit 13 according to the above equation (32).
  • a taper matrix T is generated using position vectors r m and r n .
  • the correlation matrix generation unit 31A calculates a first correlation matrix R xx based on the received signal vector x (t n ) acquired in step ST20 (step ST22). Then, the correlation matrix generation unit 31A causes the taper matrix T to act on the correlation matrix R xx as shown in the above equation (33) to generate a second correlation matrix R brd (step ST23).
  • the correlation matrix generation unit 31A supplies the ⁇ ⁇ ⁇ ⁇ weight calculation unit 33 with the inverse matrix R brd -1 for the generated correlation matrix R brd .
  • sigma weight calculation unit 33 obtains the parameter setting value from the parameter setting unit 32 (step ST24), calculates the sigma weight vector W sigma based on the parameter setting value and the inverse matrix R brd -1 (Step ST25).
  • Embodiment 2 can form a broad null in the unnecessary wave direction at the time of execution of the adaptive mono pulse, and therefore, it is unnecessary to move the aircraft equipped with the arrival direction estimation apparatus 2 or move the target. Even in the case of deviation in the wave direction, high angle measurement accuracy can be ensured.
  • ⁇ beam generation unit 41, ⁇ beam generation unit 42, monopulse ratio calculation unit 43, angle calculation unit 44 and adaptive weight calculation unit 30A are, for example, ASIC or FPGA Or the like and may be realized by a processor such as an LSI.
  • the ⁇ ⁇ ⁇ beam generation unit 41, the ⁇ beam generation unit 42, the monopulse ratio calculation unit 43, the angle measurement calculation unit 44, and the adaptive weight calculation unit 30A are realized by one or more processors including a CPU or GPU that executes a computer program. It may be done.
  • the functions of the ⁇ beam generation unit 41, the ⁇ beam generation unit 42, the monopulse ratio calculation unit 43, the angle measurement calculation unit 44, and the adaptive weight calculation unit 30A may be realized by the signal processing device 70 illustrated in FIG.
  • the direction of arrival estimation apparatus and the direction of arrival estimation method according to the present invention can be applied to various fields such as a radar system, a mobile communication system including a mobile station such as a mobile phone and a base station, and a satellite communication system. It is.
  • 1, 2 arrival direction estimation device 20 array antennas, 20 1 to 20 M antenna elements, 21 reception units, 21 1 to 21 M receivers (Rx), 22 1 to 22 M A / D converters (ADC), 30 , 30A adaptive weight operation unit, 31, 31A correlation matrix generation unit, 32 parameter setting unit, 33 ⁇ ⁇ ⁇ ⁇ weight calculation unit, 34 ⁇ weight calculation unit, 35 null width adjustment parameter setting unit, 36 taper matrix generation unit, 41 ⁇ Beam generation unit, 42 ⁇ beam generation unit, 43 monopulse ratio calculation unit, 44 angle measurement unit, 44a reference table, 45 output unit, 70 signal processing unit, 71 processor, 72 memory, 73 input interface, 74 output interface, 75 Signal path.
  • ADC A / D converters

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Abstract

This direction-of-arrival estimation device (1) comprises: a correlation matrix generation unit (31) for generating a correlation matrix on the basis of M reception signals respectively obtained from the outputs of a plurality of antenna elements (201-20M), a Σ weight calculation unit (33) for calculating M Σ weights corresponding to the M reception signals using the correlation matrix, a Δ weight calculation unit (34) for calculating M Δ weights by executing a power minimization method using the M Σ weights and two constraint conditions, a Σ beam generation unit (41) for generating a Σ beam using the M Σ weights, a Δ beam generation unit (42) for generating a Δ beam using the M Δ weights, a monopulse ratio calculation unit (43) for calculating the ratio between the Σ beam and Δ beam as a monopulse ratio, and a measured angle calculation unit (44) for calculating an estimated arrival angle value by comparing the monopulse ratio with a reference discrimination curve defining the relationship between the ratio between the Σ beam and Δ beam and the arrival angle.

Description

到来方向推定装置Direction of arrival estimation device
　本発明は、電波の到来方向（Ｄｉｒｅｃｔｉｏｎ　ｏｆ　Ａｒｒｉａｌ，ＤＯＡ）を推定する技術に関し、特に、アレイアンテナを用いて、到来電波の相関情報に基づき、到来電波の到来方向を推定する技術に関するものである。 The present invention relates to a technique for estimating the direction of arrival (DOA) of radio waves, and more particularly to a technique for estimating the arrival direction of incoming waves based on correlation information of the incoming waves using an array antenna. .
　電波の高分解能到来方向推定方式としては、モノパルス測角（ｍｏｎｏｐｕｌｓｅ　ａｎｇｌｅ　ｍｅａｓｕｒｅｍｅｎｔ）方式、ＭＵＳＩＣ（ＭＵｌｔｉｐｌｅ　Ｓｉｇｎａｌ　Ｃｌａｓｓｉｆｉｃａｔｉｏｎ）及びＥＳＰＲＩＴ（Ｅｓｔｉｍａｔｉｏｎ　ｏｆ　Ｓｉｇｎａｌ　Ｐａｒａｍｅｔｅｒｓ　ｖｉａ　Ｒｏｔａｔｉｏｎａｌ　Ｉｎｖａｒｉａｎｃｅ　Ｔｅｃｈｎｉｑｕｅｓ）などの種々の優れた到来方向推定技術が提案されている。これら到来方向推定技術の中でも、実装の容易さ及び低い演算負荷の観点からモノパルス測角方式が採用されている場合が多い。しかしながら、モノパルス測角方式は、基本的に混信分離機能を持たないので、高電力のジャミング電波もしくは海面クラッタなどの不要波の存在下では、電力の高い不要波の到来角度を誤って測定するおそれがある。 As high resolution arrival direction estimation methods for radio waves, various excellent arrival direction estimation techniques such as monopulse angle measurement method, MUSIC (MUltiple Signal Classification) and ESPRIT (Estimation of Signal Parameters via Rotational Invariance Techniques) are available. Proposed. Among these arrival direction estimation techniques, the monopulse angle measurement method is often employed in terms of ease of mounting and low computational load. However, since the monopulse angle measurement method basically does not have interference separation function, it may cause erroneous measurement of the arrival angle of the high power unwanted wave in the presence of unwanted waves such as high power jamming radio waves or sea clutter. There is.
　このような問題への対策として、アダプティブウエイトを用いてモノパルスビームを形成し、不要波の抑圧と測角とを同時に行うアダプティブモノパルスと呼ばれる技術が知られている（非特許文献１）。 As a countermeasure against such a problem, there is known a technique called adaptive monopulse in which a monopulse beam is formed using an adaptive weight and suppression of unnecessary waves and angle measurement are simultaneously performed (Non-Patent Document 1).
　しかしながら、従来のアダプティブモノパルスでは、不要波抑圧のために形成されたヌルの影響によりディスクリカーブが歪み、測角精度が劣化してしまうという課題がある（非特許文献１）。この課題への対策として、非特許文献２には、３つの拘束条件を用いてディスクリカーブの歪みを補正する技術（以下「Ｆａｎｔｅ法」という。）が提案されている。しかしながら、３つの拘束条件のためにアンテナの自由度が消費されてしまうという課題がある。 However, in the conventional adaptive monopulse, there is a problem that the discriminator curve is distorted due to the influence of the null formed for the unnecessary wave suppression, and the angle measurement accuracy is deteriorated (Non-Patent Document 1). As a solution to this problem, Non-Patent Document 2 proposes a technique (hereinafter referred to as “Fante method”) for correcting the distortion of the discriminator curve using three constraint conditions. However, there is a problem that the freedom of the antenna is consumed due to the three constraint conditions.
　上記に鑑みて本発明の目的は、２つの拘束条件を用いてディスクリカーブの歪みの補正とアンテナの自由度の過度な消費の抑制とを実現しつつ、高い測角精度をも確保することができる到来方向推定装置を提供することである。 In view of the above, it is an object of the present invention to ensure high angle measurement accuracy while realizing correction of distortion of a discriminative curve and suppression of excessive consumption of the degree of freedom of antenna using two constraint conditions. It is an object of the present invention to provide a possible DOA estimation device.
　本発明の一態様による到来方向推定装置は、アダプティブモノパルスを実行して到来電波の到来角の推定値を算出する到来方向推定装置であって、Ｍ個（Ｍは２以上の整数）のアンテナ素子の出力からそれぞれ得られたＭ個の受信信号に基づいて相関行列を生成する相関行列生成部と、前記相関行列を用いて、前記Ｍ個の受信信号にそれぞれ対応するＭ個のΣウエイトを算出するΣウエイト算出部と、前記Ｍ個のΣウエイト及び２つの拘束条件を用いた電力最小化法を実行することにより、前記Ｍ個の受信信号にそれぞれ対応するＭ個のΔウエイトを算出するΔウエイト算出部と、前記Ｍ個のΣウエイトを前記Ｍ個の受信信号にそれぞれ重み付けすることでＭ個の第１の重み付け信号を生成し、前記Ｍ個の第１の重み付け信号に基づいてΣビームを生成するΣビーム生成部と、前記Ｍ個の受信信号にそれぞれ前記Ｍ個のΔウエイトを重み付けすることでＭ個の第２の重み付け信号を生成し、前記Ｍ個の第２の重み付け信号に基づいてΔビームを生成するΔビーム生成部と、前記Σビーム生成部で生成された当該Σビームと前記Δビーム生成部で生成された当該Δビームとの間の比率をモノパルス比として算出するモノパルス比算出部と、ΣビームとΔビームとの間の比率と到来角との間の関係を定める参照用ディスクリカーブと前記モノパルス比とを比較して前記推定値を算出する測角演算部とを備えることを特徴とする。 An arrival direction estimation apparatus according to an aspect of the present invention is an arrival direction estimation apparatus that executes an adaptive monopulse to calculate an estimated value of an arrival angle of an incoming radio wave, and includes M (M is an integer of 2 or more) antenna elements. Calculating the M 生成 weights respectively corresponding to the M received signals using the correlation matrix generation unit that generates a correlation matrix based on the M received signals respectively obtained from the output of and the correlation matrix Calculating the M Δ weights respectively corresponding to the M received signals by executing the power minimizing method using the Σ weight calculating unit and the M ウ エ イ ト weights and the two constraint conditions A weight calculation unit and the M pieces of ウ エ イ ト weights are respectively weighted to the M received signals to generate M first weighting signals, and Σ be based on the M first weighting signals.第 beam generation unit for generating M, and M second weighting signals are generated by weighting the M reception signals by the M Δ weights, respectively, and the M second weighting signals are generated. And a monopulse for calculating a ratio between the ビ ー ム beam generated by the Σ beam generator and the ビ ー ム beam generated by the ビ ー ム beam generator as a monopulse ratio. A ratio calculation unit; a reference discriminator curve for determining a relationship between a ratio between Σ beam and Δ beam and an arrival angle; and an angle calculation unit which calculates the estimated value by comparing the monopulse ratio. It is characterized by having.
　本発明によれば、Σウエイト及び２つの拘束条件を用いた電力最小化法を実行することにより、Δビームを生成するためのΔウエイトが算出されるので、アダプティブモノパルスの実行時のディスクリカーブの歪みを補正することができる。よって、低演算負荷で高い測角精度を実現することが可能である。また、アンテナ自由度の過度な消費を抑制することも可能である。 According to the present invention, the Δ weight for generating the Δ beam is calculated by executing the power minimization method using the ウ エ イ ト weight and the two constraint conditions. Distortion can be corrected. Therefore, it is possible to realize high angle measurement accuracy with low calculation load. It is also possible to suppress excessive consumption of antenna freedom.
本発明に係る実施の形態１である到来方向推定装置の概略構成を示すブロック図である。It is a block diagram which shows schematic structure of the arrival direction estimation apparatus which is Embodiment 1 which concerns on this invention. ２種類のビームの例を概略的に示すグラフである。It is a graph which shows roughly the example of two types of beams. 測角値のバイアス的な誤差を説明するためのグラフである。It is a graph for demonstrating the bias-like error of angle-measurement value. アンテナ素子群の配置の一例を示す図である。It is a figure which shows an example of arrangement | positioning of an antenna element group. 到来電波の到来方向と誤差電圧との間の関係の例を示すグラフである。It is a graph which shows the example of the relationship between the arrival direction of an arrival electromagnetic wave, and an error voltage. 実施の形態１に係る到来方向推定方法の手順の一例を概略的に示すフローチャートである。7 is a flowchart schematically showing an example of the procedure of the direction of arrival estimation method according to the first embodiment. 実施の形態１の到来方向推定装置を実現するためのハードウェア構成の一例を概略的に示すブロック図である。FIG. 1 is a block diagram schematically showing an example of a hardware configuration for realizing an arrival direction estimation apparatus according to a first embodiment. 本発明に係る実施の形態２である到来方向推定装置の概略構成を示すブロック図である。It is a block diagram which shows schematic structure of the arrival direction estimation apparatus which is Embodiment 2 which concerns on this invention. 実施の形態２に係る到来方向推定方法の手順の一例を概略的に示すフローチャートである。FIG. 16 is a flowchart schematically showing an example of the procedure of the direction of arrival estimation method according to Embodiment 2. FIG.
　以下、図面を参照しつつ、本発明に係る種々の実施の形態について詳細に説明する。なお、図面全体において同一符号を付された構成要素は、同一構成及び同一機能を有するものとする。 Hereinafter, various embodiments according to the present invention will be described in detail with reference to the drawings. Note that components given the same reference numerals throughout the drawings have the same configuration and the same function.
実施の形態１．
　図１は、本発明に係る実施の形態１である到来方向推定装置１の概略構成を示すブロック図である。この到来方向推定装置１は、アダプティブモノパルスを実行して、到来電波の到来角の推定値を算出する機能を有している。アダプティブモノパルスとは、不要波方向へのヌル形成のためのアダプティブウエイト（ａｄａｐｔｉｖｅ　ｗｅｉｇｈｔｓ）を用いたモノパルス測角をいう。図１に示されるように到来方向推定装置１は、到来電波を受信するＭ個（Ｍは３以上の整数）のアンテナ素子２０１，２０２，…，２０Ｍからなるアレイアンテナ２０と、アンテナ素子２０１～２０Ｍの出力をそれぞれディジタル形式の受信信号ｘ１（ｔｎ），ｘ２（ｔｎ），…，ｘＭ（ｔｎ）に変換する受信部２１と、受信信号ｘ１（ｔｎ）～ｘＭ（ｔｎ）からΣビームＰΣを生成するΣビーム生成部４１と、受信信号ｘ１（ｔｎ）～ｘＭ（ｔｎ）からΔビームＰΔを生成するΔビーム生成部４２と、ΣビームＰΣとΔビームＰΔとの間の比率Ｒをモノパルス比として算出するモノパルス比算出部４３と、参照用ディスクリカーブとモノパルス比Ｒとを比較して到来電波の推定値を算出する測角演算部４４と、当該算出された推定値を示す推定データＭＤを外部機器に出力するデータ出力部４５とを備える。 Embodiment 1
FIG. 1 is a block diagram showing a schematic configuration of an arrival direction estimation apparatus 1 according to a first embodiment of the present invention. The arrival direction estimation apparatus 1 has a function of executing an adaptive monopulse to calculate an estimated value of an arrival angle of an incoming radio wave. Adaptive monopulse refers to monopulse angle measurement using adaptive weights for null formation in the direction of unwanted waves. As shown in FIG. 1, the arrival direction estimation apparatus 1 comprises an array antenna 20 consisting of M (M is an integer of 3 or more) antenna elements 20 1 , 20 2 ,. elements 20 1 ~ 20 M reception signals x 1 output in digital form the respective (t n), x 2 ( t n), ..., a receiving unit 21 for converting the x M (t n), the received signals x 1 ( t n) ~ x M (t n) from the sigma-beam generating unit 41 for generating a sigma beam P sigma, the received signal x 1 (t n) ~ x M (t n) Δ beam to generate a delta beam P delta from A generator 42, a monopulse ratio calculation unit 43 that calculates a ratio R between Σ beam P と and Δ beam P Δ as a monopulse ratio, and estimation of an incoming radio wave by comparing a reference discriminator curve and a monopulse ratio R Angle calculation unit 44 for calculating a value, And a data output unit 45 outputs the estimated data MD indicating the putative value to an external device.
　また、到来方向推定装置１は、受信信号ｘ１（ｔｎ）～ｘＭ（ｔｎ）からΣウエイトベクトルＷΣ及びΔウエイトベクトルＷΔをアダプティブウエイトとして算出し、これらΣウエイトベクトルＷΣ及びΔウエイトベクトルＷΔをΣビーム生成部４１及びΔビーム生成部４２にそれぞれ供給するアダプティブウエイト演算部３０を備えて構成されている。 Also, the arrival direction estimation apparatus 1 calculates Σ weight vector W Σ and Δ weight vector W Δ as adaptive weights from the received signals x 1 (t n ) to x M (t n ), and these こ れ ら weight vectors W 及 び and The adaptive weight calculation unit 30 is provided to supply the Δ weight vector W Δ to the ビーム beam generation unit 41 and the Δ beam generation unit 42, respectively.
　図１に示される放射源Ｔｇｔは、アレイアンテナ２０の中心（正面方向）に対してθｔの角度方向に存在する目標である信号源である。また、放射源Ｕ１，…，Ｕｋ（ｋは２以上の整数）は、未知の信号を発する不要波源である。放射源Ｕ１，…，Ｕｋは、アレイアンテナ２０の中心（正面方向）に対してそれぞれθ１，…，θｋの角度方向に存在する。不要波としては、たとえば、構造物などに起因して生じたマルチパス波、海面クラッタ、または妨害波が想定される。 Source Tgt shown in FIG. 1 is a signal source is a target that exists in the angular direction of theta t with respect to the center of the array antenna 20 (the front direction). Further, the radiation source U 1, ..., U k ( k is an integer of 2 or more) is unnecessary wave source that emits an unknown signal. The radiation sources U 1 ,..., U k are present at angular directions θ 1 ,..., Θ k with respect to the center (front direction) of the array antenna 20. As unnecessary waves, for example, multipath waves, sea clutter, or disturbance waves generated due to a structure or the like are assumed.
　受信部２１は、アンテナ素子２０１，…，２０ＭのＲＦ（高周波）出力に対してアナログ信号処理を施す受信器（Ｒｘ）２１１，…，２１Ｍと、これら受信器（Ｒｘ）２１１，…，２１Ｍのアナログ出力をそれぞれディジタル形式の受信信号ｘ１（ｔｎ），…，ｘＭ（ｔｎ）に変換するＡ／Ｄ変換器（ＡＤＣ）２２１，…，２２Ｍとを含んで構成されている。各受信器２１ｍは、対応するアンテナ素子２０ｍのＲＦ出力に対して、増幅処理、帯域通過処理（フィルタ処理）及び周波数変換処理などの各種信号処理を実行してアナログ信号を生成する。このアナログ信号は、同相成分及び直交成分を有する複素信号である。各Ａ／Ｄ変換器２２ｍは、対応する受信器２１ｍから入力されたアナログ信号を、ディジタル形式の複素ベースバンド信号である受信信号ｘｍ（ｔｎ）に変換する。 The receiving unit 21 includes receivers (Rx) 21 1 ,..., 21 M that perform analog signal processing on RF (high frequency) outputs of the antenna elements 20 1 ,..., 20 M , and these receivers (Rx) 21 1. , ..., 21 M each received signal x 1 in digital form the analog output of the (t n), ..., a / D converter for converting the x M (t n) (ADC ) 22 1, ..., and 22 M It is comprised including. Each receiver 21 m performs various signal processing such as amplification processing, band pass processing (filter processing) and frequency conversion processing on the RF output of the corresponding antenna element 20 m to generate an analog signal. This analog signal is a complex signal having in-phase and quadrature components. Each A / D converter 22 m converts an analog signal input from the corresponding receiver 21 m into a reception signal x m (t n ) which is a complex baseband signal in digital form.
　図１に示されるように、アダプティブウエイト演算部３０は、相関行列生成部３１、パラメータ設定部３２、Σウエイト算出部３３及びΔウエイト算出部３４を有する。相関行列生成部３１は、受信信号ｘ１（ｔｎ）～ｘＭ（ｔｎ）に基づく相関行列Ｒｘｘを生成し、その相関行列Ｒｘｘに対する逆行列Ｒｘｘ －１をΣウエイト算出部３３に供給する。受信信号ベクトルをｘ（ｔｎ）で表し、サンプリング点数をＮで表すとすれば、相関行列Ｒｘｘと受信信号ベクトルをｘ（ｔｎ）は、たとえば、次式（１），（１ａ）で与えられる。

Figure JPOXMLDOC01-appb-I000001
As shown in FIG. 1, the adaptive weight calculation unit 30 includes a correlation matrix generation unit 31, a parameter setting unit 32, a Σ weight calculation unit 33, and a Δ weight calculation unit 34. The correlation matrix generation unit 31 generates a correlation matrix R xx based on the reception signals x 1 (t n ) to x M (t n ), and the inverse matrix R xx −1 with respect to the correlation matrix R xx is a ウ エ イト weight calculation unit 33 Supply to Assuming that the received signal vector is represented by x (t n ) and the number of sampling points is represented by N, the correlation matrix R xx and the received signal vector x (t n ) can be expressed by the following equations (1) and (1a) Given.

Figure JPOXMLDOC01-appb-I000001
　ここで、ｎは、サンプリング時間の番号を示す添え字であり、１～Ｎの範囲内の整数である。上式（１）中の受信信号ベクトルｘ（ｔｎ）に付された上付き添え字「Ｈ」は、複素共役転置（エルミート転置）を示し、上式（１ａ）中の上付き添え字「Ｔ」は転置を示す。相関行列生成部３１は、たとえば、コレスキー（Ｃｈｏｌｅｓｋｙ）分解を用いて逆行列Ｒｘｘ －１を算出することができる。 Here, n is a subscript indicating a sampling time number, and is an integer in the range of 1 to N. The superscript “H” attached to the received signal vector x (t n ) in the above equation (1) indicates the complex conjugate transposition (hermite transposition), and the superscript “in the above equation (1a) "T" indicates transposition. The correlation matrix generation unit 31 can calculate, for example, the inverse matrix R xx -1 using Cholesky decomposition.
　Σウエイト算出部３３は、パラメータ設定部３２から供給されたパラメータ設定値及び逆行列Ｒｘｘ －１を用いて、Ｍ個のベクトル要素（Σウエイト）からなるＭ行１列のΣウエイトベクトルＷΣを算出することができる。 The ウ エ イ ト weight calculation unit 33 uses the parameter setting values supplied from the parameter setting unit 32 and the inverse matrix R xx −1 to generate an M-row, 1-column Σ weight vector W なる consisting of M vector elements (Σ weights). Can be calculated.
　具体的には、Σウエイト算出部３３は、ＤＣＭＰ（Ｄｉｒｅｃｔｉｏｎａｌｌｙ　Ｃｏｎｓｔｒａｉｎｅｄ　Ｍｉｎｉｍｉｚａｔｉｏｎ　ｏｆ　Ｐｏｗｅｒ）法などの電力最小化法を実行してΣウエイトベクトルＷΣを算出することが可能である。パラメータ設定部３２は、追尾処理などの処理により求めた目標方向の情報θｔ及び当該目標方向の期待する応答値ｈなどを含むパラメータ設定値γ，Ｃ（θｔ）をΣウエイト算出部３３に供給する。ＤＣＭＰ法によれば、ΣウエイトベクトルＷΣは、たとえば、次式（２）で与えられる。

Figure JPOXMLDOC01-appb-I000002
Specifically, sigma weight calculator 33, it is possible to calculate the sigma weight vector W sigma running power minimization method such as DCMP (Directionally Constrained Minimization of Power) method. The parameter setting unit 32 sends, to the ウ エ イ ト weight calculation unit 33, the parameter setting values γ and C (θ t ) including the information θ t of the target direction obtained by processing such as tracking processing and the response value h expected of the target direction. Supply. According to the DCMP method, the ウ エ イ ト weight vector W Σ is given by, for example, the following equation (2).

Figure JPOXMLDOC01-appb-I000002
　式（２）において、Ｃ（θｔ）は所望方向のステアリングベクトル（拘束ベクトル）、γは定数である。定数γは、次式（３）で表せられる。

Figure JPOXMLDOC01-appb-I000003
In equation (2), C (θ t ) is a steering vector (constraint vector) in a desired direction, and γ is a constant. The constant γ is expressed by the following equation (3).

Figure JPOXMLDOC01-appb-I000003
　また、実環境における低スナップショットなどの劣悪な条件下では、相関行列Ｒｘｘは正則とはならず、逆行列Ｒｘｘ －１の成分が不安定な値になりやすい。そのため、Σウエイト算出部３３は、状況に応じて、次式（４）に示すように、係数α及び単位行列Ｉを用いた対角荷重が施された式を使用してΣウエイトベクトルＷΣを算出してもよい。

Figure JPOXMLDOC01-appb-I000004
In addition, under poor conditions such as low snapshots in a real environment, the correlation matrix R xx is not regular, and the components of the inverse matrix R xx -1 are likely to be unstable values. Therefore, according to the situation, the は weight calculation unit 33 uses the れ た weight vector W して using the equation to which the diagonal load is applied using the coefficient α and the unit matrix I as shown in the following equation (4). May be calculated.

Figure JPOXMLDOC01-appb-I000004
　次に、Δウエイト算出部３４は、ΣウエイトベクトルＷΣ及び２つの拘束条件を用いた電力最小化法を実行することにより、受信信号ｘ１（ｔｎ）～ｘＭ（ｔｎ）にそれぞれ対応するΔウエイトからなるΔウエイトベクトルＷΔを算出することができる。ΔウエイトベクトルＷΔは、Ｍ個のベクトル要素（Δウエイト）からなるＭ行１列のベクトルである。Δウエイト算出部３４は、算出されたΔウエイトベクトルＷΔをΔビーム生成部４２に供給する。以下、Δウエイト算出部３４は、アダプティブモノパルス実行時のディスクリカーブに歪みが生じないような最適なΔウエイトベクトルＷΔを導出する。以下、Δウエイト算出部３４の処理内容について詳細に説明する。 Next, the Δ weight calculation unit 34 executes the power minimization method using the ウエ イ ト weight vector W 及 び and two constraint conditions to obtain received signals x 1 (t n ) to x M (t n ) respectively. A corresponding Δ weight vector W Δ consisting of Δ weights can be calculated. The Δ weight vector W Δ is an M-by-1 vector consisting of M vector elements (Δ weights). The Δ weight calculation unit 34 supplies the calculated Δ weight vector W Δ to the Δ beam generation unit 42. Subsequently, the Δ weight calculation unit 34 derives an optimum Δ weight vector W Δ such that distortion does not occur in the discriminator curve when the adaptive mono pulse is performed. Hereinafter, the processing content of the Δ weight calculation unit 34 will be described in detail.
　まず、アダプティブモノパルス実行前の通常のモノパルス測角により得られるディスクリカーブを定式化する。通常のモノパルス測角においては、図２に示すように、アンテナの中心方向を示す角度をθ０としたとき、アレイアンテナ２０を２分割にして得られるビーム５０Ｒ，５０Ｌの和（和信号）であるΣビームと、ビーム５０Ｒ，５０Ｌ間の差（差信号）であるΔビームとが算出される。これらΣビームとΔビームとの間の比率がディスクリカーブと定義される。ビーム５０Ｒ，５０Ｌは、それぞれ次式（５），（６）として表現可能である。

Figure JPOXMLDOC01-appb-I000005
First, the discriminator curve obtained by ordinary monopulse angle measurement before adaptive monopulse execution is formulated. In normal monopulse angle measurement, as shown in FIG. 2, when the angle indicating the center direction of the antenna is θ 0 , the sum (sum signal) of beams 50R and 50L obtained by dividing the array antenna 20 into two A certain Σ beam and a Δ beam which is a difference (difference signal) between the beams 50R and 50L are calculated. The ratio between the Σ beam and the Δ beam is defined as a discreet curve. The beams 50R and 50L can be expressed as the following equations (5) and (6), respectively.

Figure JPOXMLDOC01-appb-I000005
　上式（５），（６）において、ａ（θ）は、使用されるアレイアンテナ２０のアレーマニフォールド（ベクトル）であり、Δθは、ビームＢｒｉｇｈｔ（θ），Ｂｌｅｆｔ（θ）それぞれの中心方向からのスクイント角である。また、式（５），（６）において１次近似式を導出するために、アレーマニフォールドａ（θ）の、角度θに関する１階の偏微分は、次式（６ａ）で表現されている。

Figure JPOXMLDOC01-appb-I000006
In the above equations (5) and (6), a (θ) is the array manifold (vector) of the array antenna 20 used, and Δθ is the center of each of the beams B right (θ) and B left (θ) It is a squint angle from the direction. Further, in order to derive a linear approximation equation in the equations (5) and (6), a first-order partial differential of the array manifold a (θ) with respect to the angle θ is expressed by the following equation (6a).

Figure JPOXMLDOC01-appb-I000006
　モノパルス測角のためのΣビーム及びΔビームはそれぞれ次式（７），（８）のように表現可能である。

Figure JPOXMLDOC01-appb-I000007
The Σ beam and the Δ beam for monopulse angle measurement can be expressed as the following equations (7) and (8), respectively.

Figure JPOXMLDOC01-appb-I000007
　上式（７），（８）により、ビーム幅Δθで規格化されたディスクリカーブは、次式（９）で表現可能である（Ｒｅ（ｘ）は、ｘの実部を意味する）。

Figure JPOXMLDOC01-appb-I000008
According to the above equations (7) and (8), the discretized curve normalized by the beam width Δθ can be expressed by the following equation (9) (Re (x) means the real part of x).

Figure JPOXMLDOC01-appb-I000008
　一方、アダプティブモノパルスが実行された場合におけるディスクリカーブは、式（９）におけるウエイトベクトルＷΣ０，ＷΔ０をそれぞれアダプティブウエイトベクトルＷΣ，ＷΔに置き換えたものに等しい。よって、アダプティブモノパルスが実行された場合におけるディスクリカーブは、次式（１０）のように表現可能である。

Figure JPOXMLDOC01-appb-I000009
On the other hand, discrete curve in the case where adaptive monopulse is executed, weight vector W .SIGMA.0 in equation (9), W .DELTA.0 adaptive weight vector W sigma, respectively, equal to the replaced W delta. Therefore, the discriminant curve when the adaptive mono pulse is executed can be expressed as the following equation (10).

Figure JPOXMLDOC01-appb-I000009
　ここで、アダプティブウエイトベクトルＷΣとして上式（２）を利用し、アダプティブウエイトベクトルＷΔとして次式（１１）を利用することで、アダプティブモノパルスの実行が可能となる。

Figure JPOXMLDOC01-appb-I000010
Here, using the above equation (2) as an adaptive weight vector W sigma, by using the following equation (11) as an adaptive weight vector W delta, it is possible to perform adaptive monopulse.

Figure JPOXMLDOC01-appb-I000010
　式（１１）において、Ｔｄｉｆｆは、対角行列であり、たとえば、次式（１２）のように表現可能である。

Figure JPOXMLDOC01-appb-I000011
In equation (11), T diff is a diagonal matrix and can be expressed, for example, as in the following equation (12).

Figure JPOXMLDOC01-appb-I000011
　式（１２）においてｄｉａｇ（Ｘ）は、ベクトルＸのＭ個のベクトル要素を対角成分として有する対角行列である。Ｍが偶数のとき、対角行列Ｔｄｉｆｆにおける対角成分「１」の個数はＭ／２個であり、対角成分「－１」の個数はＭ／２個である。 In equation (12), diag (X) is a diagonal matrix having M vector elements of vector X as diagonal elements. When M is an even number, the number of diagonal components “1” in the diagonal matrix T diff is M / 2, and the number of diagonal components “−1” is M / 2.
　また、上式（５）～（９）についての議論を援用すれば、式（１２）に代えて次式（１３）の使用が可能である。

Figure JPOXMLDOC01-appb-I000012
Further, if the discussion of the above equations (5) to (9) is incorporated, it is possible to use the following equation (13) instead of the equation (12).

Figure JPOXMLDOC01-appb-I000012
　上式（１３）中、ｊは、虚数単位を表し、ｒ１，…，ｒＭは、アンテナ素子２０１，…，２０Ｍの位置ベクトルを表している。また、Ｐ（θ）の角度θに関する１階の偏微分は、所望方向の方向ベクトルの角度に対する偏微分であり、次式（１３ａ）で表現されている。

Figure JPOXMLDOC01-appb-I000013
In the above formula (13), j represents an imaginary unit, r 1, ..., r M, the antenna elements 20 1, ..., represents the position vector of 20 M. Further, the first-order partial differential with respect to the angle θ of P (θ) is a partial differential with respect to the angle of the direction vector of the desired direction, and is expressed by the following equation (13a).

Figure JPOXMLDOC01-appb-I000013
　式（１３）が使用される場合、上式（１１）は、次式（１４）で表現可能である。

Figure JPOXMLDOC01-appb-I000014
When equation (13) is used, the above equation (11) can be expressed by the following equation (14).

Figure JPOXMLDOC01-appb-I000014
　しかしながら、上式（１１），（１４）に示すようなアダプティブウエイトベクトルＷΔをそのまま使用すると、アダプティブモノパルス実行時に不要波抑圧のために形成されたヌルの影響でΔビームに歪みが生じる。図３は、アダプティブモノパルス実行前の通常のモノパルス測角の実行時（非抑圧処理）に得られる誤差電圧の分布と、式（１０）に基づくアダプティブモノパルス実行時（抑圧処理）に得られる誤差電圧の分布とを表すグラフである。図３のグラフにおいて、横軸が到来方向の角度を示し、縦軸が誤差電圧（すなわちディスクリカーブの値）を示している。図３に示されるように、アダプティブモノパルス実行前のディスクリカーブに対して、アダプティブモノパルス実行時のディスクリカーブに歪みδが生じ、測角値にバイアス的な誤差が生じることがわかる。 However, if the adaptive weight vector W Δ as shown in the above equations (11) and (14) is used as it is, distortion occurs in the Δ beam due to the effect of the null formed for unnecessary wave suppression at the time of adaptive monopulse execution. FIG. 3 shows the distribution of the error voltage obtained at the time of execution (non-suppression processing) of normal monopulse angle measurement before the adaptive mono-pulse execution, and the error voltage obtained at the time of adaptive mono-pulse execution (suppression processing) based on equation (10) It is a graph showing distribution of. In the graph of FIG. 3, the horizontal axis indicates the angle in the direction of arrival, and the vertical axis indicates the error voltage (that is, the value of the discriminator curve). As shown in FIG. 3, it is understood that distortion δ occurs in the discriminator curve when the adaptive mono pulse is executed, and a bias error occurs in the angle measurement value with respect to the discriminator curve before the adaptive mono pulse is executed.
　そこで、本実施の形態では、アダプティブウエイトベクトルＷΔに２つの拘束条件が課される。第１の拘束条件は、アダプティブモノパルスを実行せずに通常のモノパルス測角を実行して得られるディスクリカーブ（第１のディスクリカーブ）ｒｂｅｆｏｒｅ（θ）とアダプティブモノパルスを実行して得られるディスクリカーブ（第２のディスクリカーブ）ｒａｆｔｅｒ（θ）とが、アレイアンテナ２０の中心角θ＝θ０で共に零の値をとるとの条件である。すなわち、第１の拘束条件では、次式（１５）が成立する。

Figure JPOXMLDOC01-appb-I000015
Therefore, in the present embodiment, two constraint conditions are imposed on the adaptive weight vector W Δ . The first constraint condition is the discriminator curve (first discriminator curve) r before (θ) obtained by executing normal monopulse angle measurement without executing the adaptive monopulse, and the discriminator curve obtained by executing the adaptive monopulse. The (second discriminary curve) r after (θ) is the condition that both take a value of zero at the central angle θ = θ 0 of the array antenna 20. That is, the following equation (15) is satisfied under the first constraint condition.

Figure JPOXMLDOC01-appb-I000015
　上式（９），（１０）を考慮すれば、式（１５）から次式（１５ａ）が導出される。

Figure JPOXMLDOC01-appb-I000016
If the above equations (9) and (10) are considered, the following equation (15a) is derived from the equation (15).

Figure JPOXMLDOC01-appb-I000016
　式（１５ａ）より、以下の関係式（１６）が導出される。

Figure JPOXMLDOC01-appb-I000017
The following relational expression (16) is derived from the expression (15a).

Figure JPOXMLDOC01-appb-I000017
　第２の拘束条件は、第１のディスクリカーブｒｂｅｆｏｒｅ（θ）と第２のディスクリカーブｒａｆｔｅｒ（θ）とが、アレイアンテナ２０の中心角θ＝θ０で等しい傾きを有するとの条件である。すなわち、第２の拘束条件では、次式（１７）が成立する。

Figure JPOXMLDOC01-appb-I000018
The second constraint condition is the condition that the first discrete curve r before (θ) and the second discrete curve r after (θ) have equal inclination at the central angle θ = θ 0 of the array antenna 20. is there. That is, the following equation (17) is satisfied under the second constraint condition.

Figure JPOXMLDOC01-appb-I000018
　上式（１７）において、第１のディスクリカーブｒｂｅｆｏｒｅ（θ）の傾き（角度θに関する１階の偏微分）は、次式（１７ａ）で表現され、第２のディスクリカーブｒａｆｔｅｒ（θ）の傾き（角度θに関する１階の偏微分）は、次式（１７ｂ）で表現されている。

Figure JPOXMLDOC01-appb-I000019
In the above equation (17), the slope (first derivative of the first degree with respect to the angle θ) of the first discriminator r before (θ) is expressed by the following equation (17a), and the second discriminator r after (θ) The slope of (first-order partial differential with respect to angle θ) is expressed by the following equation (17b).

Figure JPOXMLDOC01-appb-I000019
　式（１７）より、以下の関係式（１８）が導出される。

Figure JPOXMLDOC01-appb-I000020
The following relational expression (18) is derived from the expression (17).

Figure JPOXMLDOC01-appb-I000020
　したがって、式（１６），（１８）からアダプティブウエイトベクトルＷΔに関して次式（１９）の拘束条件を導き出すことができる。

Figure JPOXMLDOC01-appb-I000021
　式（１９）において、ベクトルＣｐｒｏ，Ｈｐｒｏは、次式（１９ａ）で定義される。

Figure JPOXMLDOC01-appb-I000022
Therefore, the constraint condition of the following equation (19) can be derived for the adaptive weight vector W Δ from the equations (16) and (18).

Figure JPOXMLDOC01-appb-I000021
In equation (19), vectors C pro and H pro are defined by the following equation (19a).

Figure JPOXMLDOC01-appb-I000022
　次式（２０）に示されるような、式（１９）に示す拘束条件下で出力電力Ｐｏｕｔを最小化するアダプティブウエイト（Δウエイト）を求める電力最小化法を実行することにより、ディスクリカーブの歪みを解消することができるΔウエイトベクトルＷΔ＝ＷΔ－ｐｒｏを求めることができる。

Figure JPOXMLDOC01-appb-I000023
By executing a power minimization method for obtaining an adaptive weight (Δ weight) which minimizes the output power P out under the constraint condition shown in equation (19) as shown in the following equation (20): It is possible to determine Δ weight vector W Δ = W Δ -pro which can eliminate distortion.

Figure JPOXMLDOC01-appb-I000023
　式（２０）を解いた結果は、次式（２１）で表現される。

Figure JPOXMLDOC01-appb-I000024
The result of solving equation (20) is expressed by the following equation (21).

Figure JPOXMLDOC01-appb-I000024
　式（２１）において、上付きのアスタリスク「＊」は複素共役を表す。Σウエイト算出部３３は、上式（２１）に従ってΔウエイトベクトルＷΔ＝ＷΔ－ｐｒｏを算出し、このΔウエイトベクトルＷΔ－ｐｒｏをΔビーム生成部４２に供給することができる。 In equation (21), the superscript asterisk "*" represents a complex conjugate. The ウ エ イ ト weight calculation unit 33 can calculate the Δ weight vector W Δ = W Δ-pro according to the above equation (21), and can supply the Δ weight vector W Δ-pro to the Δ beam generation unit 42.
　次に、受信信号ベクトルｘ（ｔ）について、Σビーム生成部４１は、次式（２２）に従い、ΣウエイトベクトルＷΣを用いた重み付け加算を実行して、Σビームの応答値ＰΣを算出することができ、この応答値ＰΣをモノパルス比算出部４３に出力する。

Figure JPOXMLDOC01-appb-I000025
Next, for the reception signal vector x (t), the ビ ー ム beam generation unit 41 performs weighted addition using the ウ エ イ ト weight vector W に従 い according to the following equation (22) to calculate the response value P Σ of the ビ ーム beam This response value P Σ is output to the monopulse ratio calculation unit 43.

Figure JPOXMLDOC01-appb-I000025
　一方、Δビーム生成部４２は、次式（２３）に従い、ΔウエイトベクトルＷΔ－ｐｒｏを用いた重み付け加算を実行して、Δビームの応答値ＰΔ－Ｐｒｏを算出することができ、この応答値ＰΔ－Ｐｒｏをモノパルス比算出部４３に出力する。

Figure JPOXMLDOC01-appb-I000026
On the other hand, the Δ beam generation unit 42 can calculate the response value P Δ -Pro of the Δ beam by executing weighted addition using the Δ weight vector W Δ-pro according to the following equation (23). The response value P Δ-Pro is output to the monopulse ratio calculator 43.

Figure JPOXMLDOC01-appb-I000026
　モノパルス比算出部４３は、Σビームの応答値ＰΣとΣビームの応答値ＰΣとの間の比率をモノパルス比Ｒとして算出し、この算出結果を測角演算部４４に出力する。モノパルス比Ｒは、たとえば、次式（２４）で表現可能である。

Figure JPOXMLDOC01-appb-I000027
 Monopulse ratio calculator 43, sigma a ratio between the response value P sigma response values P sigma and sigma beam of the beam is calculated as the monopulse ratio R, and outputs the calculation result to the angle measuring arithmetic unit 44. The monopulse ratio R can be expressed, for example, by the following equation (24).

Figure JPOXMLDOC01-appb-I000027
　測角演算部４４は、内部メモリ４４ａに保持していた参照用ディスクリカーブｒｂｅｆｏｒｅ（θ）とモノパルス比Ｒの値とを比較することで到来角の推定値（測角値）を算出することができる。従来のアダプティブモノパルスであれば、算出されたモノパルス比が歪んだディスクリカーブ上に存在するため、推定値に誤差が生じてしまっていた。これに対し、本実施の形態では、アダプティブモノパルス実行時に、ディスクリカーブに大きな歪みが生じないので、従来技術よりも高精度に測角値を算出することが可能である。 The angle measurement calculation unit 44 calculates an estimated value (angle measurement value) of the arrival angle by comparing the reference discriminator curve r before (θ) held in the internal memory 44 a with the value of the monopulse ratio R. Can. In the case of the conventional adaptive monopulse, an error occurs in the estimated value because the calculated monopulse ratio is present on the distorted discriminator. On the other hand, in the present embodiment, a large distortion does not occur in the discriminator curve when the adaptive mono pulse is performed, so that it is possible to calculate the angle measurement value with higher accuracy than the prior art.
　図５は、図４に示されるように６４個のアンテナ素子がＸ軸方向及びＹ軸方向に沿って２次元状に配置された素子方形アレーを用いて、４種類の誤差電圧の分布（ディスクリカーブ）を計算した結果を示すグラフである。図４においてλは波長（単位：メートル）を示す。図５のグラフでは、目標方向と不要波との間の離角がビーム幅の１／４程度であり、かつ不要波電力が所望電力に比べて２０ｄＢ高い状況が想定されている。また、図５のグラフにおいて、実線は、非抑圧処理（上記した通常のモノパルス測角）により得られたディスクリカーブを示し、丸印記号は、本実施の形態に係るアダプティブモノパルスの実施例により得られたディスクリカーブを示し、十字記号は、３つの拘束条件を使用するＦａｎｔｅ法により得られたディスクリカーブを示し、破線は、拘束条件を使用しない従来のアダプティブモノパルスにより得られたディスクリカーブを示している。図５からわかるように、高電力の不要波がメインビーム内に存在するような厳しい条件であっても、ディスクリカーブの歪みが補正される。さらに、実施例で得られる補正の効果は、３つの拘束条件を使用するＦａｎｔｅ法で得られる補正の効果よりも高いことが確認できる。 FIG. 5 shows the distribution of four types of error voltages (discs using a square array of elements in which 64 antenna elements are two-dimensionally arranged along the X-axis direction and the Y-axis direction as shown in FIG. It is a graph which shows the result of having calculated recurve. In FIG. 4, λ indicates a wavelength (unit: meter). In the graph of FIG. 5, it is assumed that the separation angle between the target direction and the unwanted wave is about 1⁄4 of the beam width, and the unwanted wave power is 20 dB higher than the desired power. Further, in the graph of FIG. 5, the solid line indicates the discriminator curve obtained by the non-suppression process (the above-mentioned normal monopulse angle measurement), and the circle symbol is obtained by the example of the adaptive monopulse according to the present embodiment. Indicates a discreet curve obtained by the Fante method using three constraints, and a broken line indicates a discreet curve obtained by the conventional adaptive monopulse using no constraint condition. There is. As can be seen from FIG. 5, the distortion of the discriminator curve is corrected even under severe conditions where high power unwanted waves are present in the main beam. Furthermore, it can be confirmed that the effect of the correction obtained in the example is higher than the effect of the correction obtained by the Fante method using three constraint conditions.
　次に、図６を参照しつつ、本実施の形態に係る到来方向推定処理の手順の一例を簡単に説明する。図６は、実施の形態１に係る到来方向推定処理の手順の一例を概略的に示すフローチャートである。 Next, an example of the procedure of the arrival direction estimation process according to the present embodiment will be briefly described with reference to FIG. FIG. 6 is a flowchart schematically showing an example of a procedure of an arrival direction estimation process according to the first embodiment.
　先ず、相関行列生成部３１は、受信部２１から出力された受信信号ベクトルｘ（ｔｎ）を取得し（ステップＳＴ２０）、上記のとおり、この受信信号ベクトルｘ（ｔｎ）に基づいて相関行列Ｒｘｘを算出する（ステップＳＴ２２）。相関行列生成部３１は、生成された相関行列Ｒｘｘに対する逆行列Ｒｘｘ －１をΣウエイト算出部３３に供給する。 First, the correlation matrix generation unit 31 obtains the reception signal vector x (t n ) output from the reception unit 21 (step ST20), and as described above, the correlation matrix is obtained based on the reception signal vector x (t n ). R xx is calculated (step ST22). The correlation matrix generation unit 31 supplies the inverse matrix R xx −1 to the generated correlation matrix R xx to the ウ エ イト weight calculation unit 33.
　次に、Σウエイト算出部３３は、上記のとおり、パラメータ設定部３２からパラメータ設定値を取得し（ステップＳＴ２４）、このパラメータ設定値及び逆行列Ｒｘｘ －１に基づいてΣウエイトベクトルＷΣを算出する（ステップＳＴ２５）。Σウエイト算出部３３は、算出されたΣウエイトベクトルＷΣをΔウエイト算出部３４とΣビーム生成部４１とに供給する。 Next, the Σ weight calculation unit 33 acquires the parameter setting value from the parameter setting unit 32 as described above (step ST24), and the Σ weight vector W を is obtained based on the parameter setting value and the inverse matrix R xx −1. It calculates (step ST25). The ウ エ イ ト weight calculating unit 33 supplies the calculated ウ エイト weight vector W に to the Δ weight calculating unit 34 and the ビ ー ム beam generating unit 41.
　その後、Δウエイト算出部３４は、上記のとおり、ΣウエイトベクトルＷΣ及び２つの拘束条件を用いた電力最小化法を実行することにより、ΔウエイトベクトルＷΔを算出する（ステップＳＴ２６）。Δウエイト算出部３４は、算出されたΔウエイトベクトルＷΔをΔビーム生成部４２に供給する。 Thereafter, the Δ weight calculation unit 34 calculates the Δ weight vector W Δ by executing the power minimization method using the ウ エ イ ト weight vector W 及 び and the two constraint conditions as described above (step ST26). The Δ weight calculation unit 34 supplies the calculated Δ weight vector W Δ to the Δ beam generation unit 42.
　次に、Σビーム生成部４１は、ΣウエイトベクトルＷΣを用いてΣビーム応答値を算出し（ステップＳＴ２７）、Δビーム生成部４２は、ΔウエイトベクトルＷΔを用いてΔビーム応答値を算出する（ステップＳＴ２８）。ここで、ステップＳＴ２７，ＳＴ２８の実行順序は、特に制限されるものではない。 Next, sigma beam generating unit 41 uses the sigma weight vector W sigma calculates the sigma beam response value (step ST27), delta beam generating portion 42, a delta beam response value using the delta weight vector W delta It calculates (step ST28). Here, the execution order of steps ST27 and ST28 is not particularly limited.
　次に、Σビームの応答値ＰΣとΣビームの応答値ＰΣとの間の比率をモノパルス比Ｒとして算出し、この算出結果を測角演算部４４に出力する（ステップＳＴ２９）。そして、測角演算部４４は、参照用ディスクリカーブｒｂｅｆｏｒｅ（θ）とモノパルス比Ｒの値とを比較することで到来角の推定値（測角値）を算出する（ステップＳＴ３０）。その後、データ出力部４５は、推定値を示す推定データＭＤを外部機器に出力する（ステップＳＴ３１）。 Next, sigma a ratio between the response value P sigma response values P sigma and sigma beam of the beam is calculated as the monopulse ratio R, and outputs the calculation result to the angle measuring operation section 44 (step ST29). Then, the angle measurement calculation unit 44 compares the reference discriminator curve r before (θ) with the value of the monopulse ratio R to calculate an estimated value (angle measurement value) of the arrival angle (step ST30). Thereafter, the data output unit 45 outputs the estimated data MD indicating the estimated value to the external device (step ST31).
　上記した到来方向推定装置１の構成のうち、Σビーム生成部４１、Δビーム生成部４２、モノパルス比算出部４３、測角演算部４４及びアダプティブウエイト演算部３０は、たとえば、ＡＳＩＣ（Ａｐｐｌｉｃａｔｉｏｎ　Ｓｐｅｃｉｆｉｃ　Ｉｎｔｅｇｒａｔｅｄ　Ｃｉｒｃｕｉｔ）またはＦＰＧＡ（Ｆｉｅｌｄ－Ｐｒｏｇｒａｍｍａｂｌｅ　Ｇａｔｅ　Ａｒｒａｙ）などのＬＳＩ（Ｌａｒｇｅ　Ｓｃａｌｅ　Ｉｎｔｅｇｒａｔｅｄ　ｃｉｒｃｕｉｔ）からなるプロセッサで実現されればよい。あるいは、Σビーム生成部４１、Δビーム生成部４２、モノパルス比算出部４３、測角演算部４４及びアダプティブウエイト演算部３０は、コンピュータプログラムを実行するＣＰＵ（Ｃｅｎｔｒａｌ　Ｐｒｏｃｅｓｓｉｎｇ　Ｕｎｉｔ）またはＧＰＵ（Ｇｒａｐｈｉｃｓ　Ｐｒｏｃｅｓｓｉｎｇ　Ｕｎｉｔ）を含む単数または複数のプロセッサで実現されてもよい。 In the configuration of the arrival direction estimation apparatus 1 described above, the Σ beam generation unit 41, the Δ beam generation unit 42, the monopulse ratio calculation unit 43, the angle measurement calculation unit 44, and the adaptive weight calculation unit 30 are, for example, ASIC (Application Specific Integrated) It may be realized by a processor including an LSI (Large Scale Integrated circuit) such as a Circuit) or an FPGA (Field-Programmable Gate Array). Alternatively, the Σ beam generation unit 41, the Δ beam generation unit 42, the monopulse ratio calculation unit 43, the angle measurement calculation unit 44, and the adaptive weight calculation unit 30 may be a central processing unit (CPU) or a graphics processing unit (GPU) that executes a computer program. And may be realized by one or more processors.
　図７は、Σビーム生成部４１、Δビーム生成部４２、モノパルス比算出部４３、測角演算部４４及びアダプティブウエイト演算部３０の機能を実現するハードウェア構成例を示すブロック図である。図７に示される信号処理装置７０は、半導体集積回路で構成されたプロセッサ７１、メモリ７２、入力インタフェース部７３、出力インタフェース部７４及び信号路７５を含んで構成されている。信号路７５は、プロセッサ７１、メモリ７２、入力インタフェース部７３、出力インタフェース部７４を相互に接続するためのバスである。入力インタフェース７３は、受信部２１から入力された受信信号ベクトルｘ（ｔｎ）を示す受信データＲＳを取得し、この受信データＲＳを信号路７５を介してプロセッサ７１に転送する機能を有する回路である。プロセッサ７１は、信号路７５及び出力インタフェース７４を介して表示装置などの外部機器と接続されている。 FIG. 7 is a block diagram showing an example of a hardware configuration for realizing the functions of the Σ beam generation unit 41, the Δ beam generation unit 42, the monopulse ratio calculation unit 43, the angle calculation unit 44 and the adaptive weight calculation unit 30. A signal processing device 70 shown in FIG. 7 includes a processor 71 formed of a semiconductor integrated circuit, a memory 72, an input interface unit 73, an output interface unit 74, and a signal path 75. The signal path 75 is a bus for mutually connecting the processor 71, the memory 72, the input interface unit 73, and the output interface unit 74. The input interface 73 is a circuit having a function of acquiring the reception data RS indicating the reception signal vector x (t n ) input from the reception unit 21 and transferring the reception data RS to the processor 71 via the signal path 75. is there. The processor 71 is connected to an external device such as a display device via the signal path 75 and the output interface 74.
　メモリ７２は、たとえば、本実施の形態の到来方向推定装置１の信号処理機能を実現するための各種プログラムを記憶するプログラムメモリ、プロセッサ７１が信号処理を実行する際に使用されるワークメモリ、及び、当該信号処理で使用されるデータが展開されるメモリを含む。メモリ７２としては、ＲＯＭ（Ｒｅａｄ　Ｏｎｌｙ　Ｍｅｍｏｒｙ）及びＳＤＲＡＭ（Ｓｙｎｃｈｒｏｎｏｕｓ　Ｄｙｎａｍｉｃ　Ｒａｎｄｏｍ　Ａｃｃｅｓｓ　Ｍｅｍｏｒｙ）などの複数の半導体メモリが使用されればよい。 The memory 72 is, for example, a program memory for storing various programs for realizing the signal processing function of the arrival direction estimation apparatus 1 of the present embodiment, a work memory used when the processor 71 performs signal processing, And a memory in which data used in the signal processing is expanded. As the memory 72, a plurality of semiconductor memories such as a ROM (Read Only Memory) and an SDRAM (Synchronous Dynamic Random Access Memory) may be used.
　なお、図７の例では、単一のプロセッサ７１を用いて構成されているが、これに限定されるものではない。互いに連携して動作する複数個のプロセッサを用いて到来方向推定装置１の信号処理機能が実現されてもよい。さらには、Σビーム生成部４１、Δビーム生成部４２、モノパルス比算出部４３、測角演算部４４及びアダプティブウエイト演算部３０のいずれかが専用のハードウェアで構成されてもよい。 In the example of FIG. 7, the single processor 71 is used, but the present invention is not limited to this. The signal processing function of the arrival direction estimation apparatus 1 may be realized using a plurality of processors operating in cooperation with each other. Furthermore, any of the ビ ー ム beam generation unit 41, the Δ beam generation unit 42, the monopulse ratio calculation unit 43, the angle measurement calculation unit 44, and the adaptive weight calculation unit 30 may be configured by dedicated hardware.
　以上に説明したように実施の形態１では、Δウエイト算出部３４は、ΣウエイトベクトルＷΣ及び２つの拘束条件を用いた電力最小化法を実行することにより、Δビームを生成するためのΔウエイトベクトルＷΔ＝ＷΔ－ｐｒｏを算出するので、アダプティブモノパルスの実行時におけるディスクリカーブの歪みを補正することができる。よって、低演算負荷で高い測角精度を実現することが可能である。また、２つの拘束条件しか使用しないため、アンテナ自由度の過度な消費を抑制することも可能である。 As described above, in the first embodiment, the Δ weight calculation unit 34 executes the power minimization method using the ウエ イ ト weight vector W 及 び and two constraint conditions to generate Δ beam for generating the Δ beam. Since the weight vector W Δ = W Δ-pro is calculated, it is possible to correct the distortion of the discriminator curve at the time of execution of the adaptive mono pulse. Therefore, it is possible to realize high angle measurement accuracy with low calculation load. Also, since only two constraints are used, it is possible to suppress excessive consumption of antenna freedom.
実施の形態２．
　図８は、本発明に係る実施の形態２である到来方向推定装置２の概略構成を示すブロック図である。上記実施の形態１の到来方向推定装置１では、アダプティブアレイが使用され、不要波の抑圧が空間的に局所的な領域で行われる。一方、実環境においては、アダプティブウエイトＷΔ，ＷΣが計算された後、到来方向推定装置を搭載する機体の揺動、または目標の運動などの環境変動に起因して、ヌルを形成した方向から不要波源が外れてしまう場合が考えられる。このような場合には、抑圧性能が低下して測角精度を低下させるおそれがある。このような場合に対処するため、本実施の形態の到来方向推定装置２は、ブロードなヌルを形成可能なアダプティブウエイトを算出することができる。 Second Embodiment
FIG. 8 is a block diagram showing a schematic configuration of the arrival direction estimation apparatus 2 according to the second embodiment of the present invention. In the arrival direction estimation apparatus 1 of the first embodiment, an adaptive array is used, and suppression of unnecessary waves is performed in a spatially local region. On the other hand, in the real environment, after the adaptive weights W Δ and W 計算 are calculated, the direction in which the null is formed due to the environmental fluctuation such as the oscillation of the airframe equipped with the arrival direction estimation device or the movement of the target. It is possible that the unnecessary wave source may be removed from the In such a case, there is a possibility that the suppression performance is lowered and the angle measurement accuracy is lowered. In order to cope with such a case, the arrival direction estimation apparatus 2 of the present embodiment can calculate an adaptive weight capable of forming a broad null.
　本実施の形態到来方向推定装置２の構成は、上記実施の形態のアダプティブウエイト演算部３０（図１）に代えて図８のアダプティブウエイト演算部３０Ａを有する点を除いて、上記実施の形態１の到来方向推定装置１の構成と同じである。 The configuration of the arrival direction estimation apparatus 2 of the present embodiment is that of the first embodiment except that it has the adaptive weight calculation unit 30A of FIG. 8 instead of the adaptive weight calculation unit 30 (FIG. 1) of the above embodiment. The configuration is the same as that of the arrival direction estimation apparatus 1 of FIG.
　図８に示されるように、アダプティブウエイト演算部３０Ａは、相関行列生成部３１Ａ、パラメータ設定部３２、Σウエイト算出部３３、Δウエイト算出部３４、ヌル幅調整用のパラメータ設定部３５及びテーパー行列生成部３６を有する。本実施の形態におけるパラメータ設定部３２、Σウエイト算出部３３及びΔウエイト算出部３４の構成は、上記実施の形態１におけるパラメータ設定部３２、Σウエイト算出部３３及びΔウエイト算出部３４の構成と同じである。 As shown in FIG. 8, the adaptive weight calculation unit 30A includes a correlation matrix generation unit 31A, a parameter setting unit 32, a ウ エ イ ト weight calculation unit 33, a Δ weight calculation unit 34, a null width adjustment parameter setting unit 35, and a taper matrix. A generation unit 36 is provided. The configuration of parameter setting unit 32, Σ weight calculation unit 33 and Δ weight calculation unit 34 in the present embodiment is the same as the configuration of parameter setting unit 32, 設定 weight calculation unit 33 and Δ weight calculation unit 34 in the first embodiment. It is the same.
　ヌル幅調整用のパラメータ設定部３５は、ヌル幅制御用のテーパー行列Ｔの生成に必要なパラメータ設定値ｕθ，ｕφをテーパー行列生成部３６に供給する。テーパー行列生成部３６は、パラメータ設定値ｕθ，ｕφを用いてテーパー行列Ｔを生成する。以下、テーパー行列Ｔの生成方法について詳細に説明する。 The parameter setting unit for null width adjustment supplies the parameter set values u θ and u φ necessary for generating the taper matrix T for null width control to the taper matrix generation unit. The taper matrix generation unit 36 generates a taper matrix T using the parameter setting values u θ and u φ . The method of generating the taper matrix T will be described in detail below.
　まず、定式化において、議論を簡単にするために、無雑音、不要波１波のみ到来する場合を考える。この場合の不要波の信号ベクトルｘｕ（ｔ）は、不要波方向のステアリングベクトルをａｕ、不要波の複素振幅をｕ（ｔ）とすると次式（２５）のように表せる。

Figure JPOXMLDOC01-appb-I000028
First, in the formulation, in order to simplify the discussion, consider the case where only one unwanted noise wave arrives. The signal vector x u (t) of the unwanted wave in this case can be expressed as in the following equation (25), where a u is the steering vector in the unwanted wave direction and u (t) is the complex amplitude of the unwanted wave.

Figure JPOXMLDOC01-appb-I000028
　このとき、上記不要波に関する相関行列のｍ行ｎ列目成分は、次式（２６）のように表現可能である。

Figure JPOXMLDOC01-appb-I000029
At this time, the m th row and n th column component of the correlation matrix related to the unnecessary wave can be expressed as in the following equation (26).

Figure JPOXMLDOC01-appb-I000029
　ここで、Ｅ［Ｘ］はＸのアンサンブル平均を、Ｐｕは不要波の電力を、λは不要波の波長を、ｒｍは第ｍ番目のアンテナ素子２０ｍの位置ベクトルを、ｒｎは第ｎ番目のアンテナ素子２０ｎの位置ベクトルを、Ｌ（θｕ，φｕ）は不要波の到来する方向ベクトルをそれぞれ表す。 Here, E [X] is the ensemble average of X, P u is the power of the unnecessary wave, λ is the wavelength of the unnecessary wave, r m is the position vector of the mth antenna element 20 m , r n is L (θ u , φ u ) represents a direction vector in which the unwanted wave arrives, for example, the position vector of the n-th antenna element 20 n .
　上式（２５）について、不要波が、仰角方向及び方位角方向に、次の不等式（２６ａ）に示す角度拡がりを有するものとする。

Figure JPOXMLDOC01-appb-I000030
Regarding the above equation (25), it is assumed that the unwanted wave has an angular spread shown in the following inequality (26a) in the elevation direction and the azimuth direction.

Figure JPOXMLDOC01-appb-I000030
　このとき、上式（２６）は、次式（２７）に示すように変形可能である。

Figure JPOXMLDOC01-appb-I000031
At this time, the above equation (26) can be modified as shown in the following equation (27).

Figure JPOXMLDOC01-appb-I000031
　また、式（２７）において方向ベクトルの変位は、次式（２８）のような一次近似で展開できる。

Figure JPOXMLDOC01-appb-I000032
Further, the displacement of the direction vector in Equation (27) can be expanded by a first-order approximation as in the following Equation (28).

Figure JPOXMLDOC01-appb-I000032
　式（２８）を用いて式（２７）を整理すると、次式（２９）が得られる。

Figure JPOXMLDOC01-appb-I000033
If Expression (27) is rearranged using Expression (28), the following Expression (29) is obtained.

Figure JPOXMLDOC01-appb-I000033
　式（２９）により、不要波がある空間的な広がりを持つ場合の相関行列Ｒｕ－ｂｒｏａｄは、次式（３０）に示すように行列Ｒｕとテーパー行列Ｔとの要素積（アダマール積）で表すことができる。

Figure JPOXMLDOC01-appb-I000034
The correlation matrix R u-broad in the case where the unnecessary wave has a spatial spread according to the equation (29) is an element product (Hadamard product) of the matrix R u and the taper matrix T as shown in the following equation (30) Can be represented by

Figure JPOXMLDOC01-appb-I000034
　また、テーパー行列Ｔは、次式（３１）のように表現可能である。

Figure JPOXMLDOC01-appb-I000035
Further, the taper matrix T can be expressed as the following equation (31).

Figure JPOXMLDOC01-appb-I000035
　ここで、次式（３１ａ）で定義されるパラメータｕθ，ｕφは、未知である。

Figure JPOXMLDOC01-appb-I000036
Here, the parameters u θ and u φ defined by the following equation (31a) are unknown.

Figure JPOXMLDOC01-appb-I000036
　よって、式（３１ａ）を用いれば、上式（３１）は、次式（３２）のように表現可能である。

Figure JPOXMLDOC01-appb-I000037
Therefore, if Formula (31a) is used, the above Formula (31) can be expressed like following Formula (32).

Figure JPOXMLDOC01-appb-I000037
　仮に、事前にＭＵＳＩＣ（ＭＵｌｔｉｐｌｅ　Ｓｉｇｎａｌ　Ｃｌａｓｓｉｆｉｃａｔｉｏｎ）またはＥＳＰＲＩＴ（Ｅｓｔｉｍａｔｉｏｎ　ｏｆ　Ｓｉｇｎａｌ Ｐａｒａｍｅｔｅｒｓ　ｖｉａ　Ｒｏｔａｔｉｏｎａｌ　Ｉｎｖａｒｉａｎｃｅ　Ｔｅｃｈｎｉｑｕｅｓ）などの種々の到来方向推定手法で、不要波の到来方位及び角度幅が概ね判明している場合は、上式（３１ａ）から、パラメータｕθ，ｕφの値が直接計算されてもよい。 If various directions of arrival estimation methods such as MUTIC (MUltiple Signal Classification) or ESPRIT (Estimation of Signal Parameters via Rotational Invariance Techniques) are used, it is recommended The values of the parameters u θ and u φ may be calculated directly from equation (31a).
　したがって、テーパー行列生成部３６は、上式（３２）に従い、ヌル幅調整パラメータ設定部１３より出力されたパラメータｕθ，ｕφの設定値、及び、アンテナ素子２０ｍ，２０ｎの位置ベクトルｒｍ，ｒｎを用いて、ヌル幅制御のためのテーパー行列Ｔを求めることができる。アンテナ素子２０１～２０Ｍの任意のアレー配置で、かつ方位角方向及び仰角方向に関してヌル幅が調整可能である点は、本実施の形態の特徴の１つである。 Therefore, taper matrix generation unit 36 sets the setting values of parameters u θ and u φ output from null width adjustment parameter setting unit 13 according to the above equation (32), and position vectors r of antenna elements 20 m and 20 n. The taper matrix T for null width control can be determined using m 1 and r n . The arbitrary array arrangement of the antenna elements 20 1 to 20 M and the fact that the null width can be adjusted in the azimuth and elevation directions is one of the features of this embodiment.
　テーパー行列生成部３６は、算出されたテーパー行列Ｔを相関行列生成部３１Ａに供給する。相関行列生成部３１Ａは、次式（３３）に示すように相関行列Ｒｘｘにテーパー行列Ｔを作用させて修正された相関行列Ｒｂｒｄ（相関行列Ｒｘｘとテーパー行列Ｔとの要素積）を生成することができる。

Figure JPOXMLDOC01-appb-I000038
The taper matrix generation unit 36 supplies the calculated taper matrix T to the correlation matrix generation unit 31A. The correlation matrix generation unit 31A generates the correlation matrix R brd (element product of the correlation matrix R xx and the taper matrix T) corrected by applying the taper matrix T to the correlation matrix R xx as shown in the following equation (33). Can be generated.

Figure JPOXMLDOC01-appb-I000038
　相関行列生成部３１Ａは、修正された相関行列Ｒｂｒｄに対する逆行列Ｒｂｒｄ －１をΣウエイト算出部３３に供給する。Σウエイト算出部３３は、上記実施の形態１の場合と同様に、逆行列Ｒｂｒｄ －１を用いた電力最小化法を実行することにより、ΣウエイトＷΣを算出することができる。 The correlation matrix generation unit 31A supplies the inverse matrix R brd -1 for the corrected correlation matrix R brd to the ウ エ イ ト weight calculation unit 33. The Σ weight calculation unit 33 can calculate the ウ エ イ ト weight W Σ by executing the power minimization method using the inverse matrix R brd −1 as in the first embodiment.
　次に、図９を参照しつつ、本実施の形態に係る到来方向推定処理の手順の一例を簡単に説明する。図９は、実施の形態２に係る到来方向推定処理の手順の一例を概略的に示すフローチャートである。図９のフローチャートの手順は、ステップＳＴ２１，ＳＴ２３を有する点を除いて、図６のフローチャートの手順と同じである。 Next, an example of the procedure of the arrival direction estimation process according to the present embodiment will be briefly described with reference to FIG. FIG. 9 is a flowchart schematically showing an example of a procedure of an arrival direction estimation process according to the second embodiment. The procedure of the flowchart of FIG. 9 is the same as the procedure of the flowchart of FIG. 6 except that steps ST21 and ST23 are included.
　ステップＳＴ２１では、テーパー行列生成部３６は、上式（３２）に従い、ヌル幅調整パラメータ設定部１３より供給された、パラメータｕθ，ｕφの設定値、及び、アンテナ素子２０ｍ，２０ｎの位置ベクトルｒｍ，ｒｎを用いてテーパー行列Ｔを生成する。次いで、相関行列生成部３１Ａは、ステップＳＴ２０で取得された受信信号ベクトルｘ（ｔｎ）に基づいて第１の相関行列Ｒｘｘを算出する（ステップＳＴ２２）。そして、相関行列生成部３１Ａは、上式（３３）に示したように相関行列Ｒｘｘにテーパー行列Ｔを作用させて第２の相関行列Ｒｂｒｄを生成する（ステップＳＴ２３）。ここで、相関行列生成部３１Ａは、生成された相関行列Ｒｂｒｄに対する逆行列Ｒｂｒｄ －１をΣウエイト算出部３３に供給する。 In step ST21, the taper matrix generation unit 36 sets the set values of the parameters u θ and u φ and the antenna elements 20 m and 20 n supplied from the null width adjustment parameter setting unit 13 according to the above equation (32). A taper matrix T is generated using position vectors r m and r n . Next, the correlation matrix generation unit 31A calculates a first correlation matrix R xx based on the received signal vector x (t n ) acquired in step ST20 (step ST22). Then, the correlation matrix generation unit 31A causes the taper matrix T to act on the correlation matrix R xx as shown in the above equation (33) to generate a second correlation matrix R brd (step ST23). Here, the correlation matrix generation unit 31A supplies the ウ エ イ ト weight calculation unit 33 with the inverse matrix R brd -1 for the generated correlation matrix R brd .
　その後、Σウエイト算出部３３は、上記のとおり、パラメータ設定部３２からパラメータ設定値を取得し（ステップＳＴ２４）、このパラメータ設定値及び逆行列Ｒｂｒｄ －１に基づいてΣウエイトベクトルＷΣを算出することとなる（ステップＳＴ２５）。 Thereafter, sigma weight calculation unit 33, as described above, obtains the parameter setting value from the parameter setting unit 32 (step ST24), calculates the sigma weight vector W sigma based on the parameter setting value and the inverse matrix R brd -1 (Step ST25).
　以上に説明したように実施の形態２は、アダプティブモノパルスの実行時に不要波方向にブロードなヌルを形成することができるため、到来方向推定装置２を搭載する機体の移動または目標の移動に伴う不要波方向のズレが生じた場合でも、高い測角精度を確保することができる。 As described above, Embodiment 2 can form a broad null in the unnecessary wave direction at the time of execution of the adaptive mono pulse, and therefore, it is unnecessary to move the aircraft equipped with the arrival direction estimation apparatus 2 or move the target. Even in the case of deviation in the wave direction, high angle measurement accuracy can be ensured.
　なお、上記した到来方向推定装置２の構成のうち、Σビーム生成部４１、Δビーム生成部４２、モノパルス比算出部４３、測角演算部４４及びアダプティブウエイト演算部３０Ａは、たとえば、ＡＳＩＣまたはＦＰＧＡなどのＬＳＩからなるプロセッサで実現されればよい。あるいは、Σビーム生成部４１、Δビーム生成部４２、モノパルス比算出部４３、測角演算部４４及びアダプティブウエイト演算部３０Ａは、コンピュータプログラムを実行するＣＰＵまたはＧＰＵを含む単数または複数のプロセッサで実現されてもよい。図７に示した信号処理装置７０によって、Σビーム生成部４１、Δビーム生成部４２、モノパルス比算出部４３、測角演算部４４及びアダプティブウエイト演算部３０Ａの機能が実現されてもよい。 In the configuration of arrival direction estimation apparatus 2 described above, Σ beam generation unit 41, Δ beam generation unit 42, monopulse ratio calculation unit 43, angle calculation unit 44 and adaptive weight calculation unit 30A are, for example, ASIC or FPGA Or the like and may be realized by a processor such as an LSI. Alternatively, the ビ ー ム beam generation unit 41, the Δ beam generation unit 42, the monopulse ratio calculation unit 43, the angle measurement calculation unit 44, and the adaptive weight calculation unit 30A are realized by one or more processors including a CPU or GPU that executes a computer program. It may be done. The functions of the Σ beam generation unit 41, the Δ beam generation unit 42, the monopulse ratio calculation unit 43, the angle measurement calculation unit 44, and the adaptive weight calculation unit 30A may be realized by the signal processing device 70 illustrated in FIG.
　以上、図面を参照して本発明に係る種々の実施の形態について述べたが、これら実施の形態は本発明の例示であり、これら実施の形態以外の様々な形態を採用することもできる。
　なお、本発明の範囲内において、上記実施の形態１，２の自由な組み合わせ、各実施の形態の任意の構成要素の変形、または各実施の形態の任意の構成要素の省略が可能である。 As mentioned above, although various embodiments according to the present invention have been described with reference to the drawings, these embodiments are merely examples of the present invention, and various embodiments other than these embodiments can be adopted.
Within the scope of the present invention, free combinations of Embodiments 1 and 2 described above, deformation of any component of each embodiment, or omission of any component of each embodiment are possible.
　本発明に係る到来方向推定装置及び到来方向推定方法は、たとえば、レーダシステム、携帯電話などの移動局と基地局とを含む移動体通信システム、及び、衛星通信システムなどの種々の分野に適用可能である。 The direction of arrival estimation apparatus and the direction of arrival estimation method according to the present invention can be applied to various fields such as a radar system, a mobile communication system including a mobile station such as a mobile phone and a base station, and a satellite communication system. It is.
　１，２　到来方向推定装置、２０　アレイアンテナ、２０１～２０Ｍ　アンテナ素子、２１　受信部、２１１～２１Ｍ　受信器（Ｒｘ）、２２１～２２Ｍ　Ａ／Ｄ変換器（ＡＤＣ）、３０，３０Ａ　アダプティブウエイト演算部、３１，３１Ａ　相関行列生成部、３２　パラメータ設定部、３３　Σウエイト算出部、３４　Δウエイト算出部、３５　ヌル幅調整用のパラメータ設定部、３６　テーパー行列生成部、４１　Σビーム生成部、４２　Δビーム生成部、４３　モノパルス比算出部、４４　測角演算部、４４ａ　参照テーブル、４５　出力部、７０　信号処理装置、７１　プロセッサ、７２　メモリ、７３　入力インタフェース、７４　出力インタフェース、７５　信号路。 1, 2 arrival direction estimation device, 20 array antennas, 20 1 to 20 M antenna elements, 21 reception units, 21 1 to 21 M receivers (Rx), 22 1 to 22 M A / D converters (ADC), 30 , 30A adaptive weight operation unit, 31, 31A correlation matrix generation unit, 32 parameter setting unit, 33 ウ エ イ ト weight calculation unit, 34 Δ weight calculation unit, 35 null width adjustment parameter setting unit, 36 taper matrix generation unit, 41 Σ Beam generation unit, 42 Δ beam generation unit, 43 monopulse ratio calculation unit, 44 angle measurement unit, 44a reference table, 45 output unit, 70 signal processing unit, 71 processor, 72 memory, 73 input interface, 74 output interface, 75 Signal path.

Claims (6)

  1. 　アダプティブモノパルスを実行して到来電波の到来角の推定値を算出する到来方向推定装置であって、
    　Ｍ個（Ｍは２以上の整数）のアンテナ素子の出力からそれぞれ得られたＭ個の受信信号に基づいて相関行列を生成する相関行列生成部と、
    　前記相関行列を用いて、前記Ｍ個の受信信号にそれぞれ対応するＭ個のΣウエイトを算出するΣウエイト算出部と、
    　前記Ｍ個のΣウエイト及び２つの拘束条件を用いた電力最小化法を実行することにより、前記Ｍ個の受信信号にそれぞれ対応するＭ個のΔウエイトを算出するΔウエイト算出部と、
    　前記Ｍ個のΣウエイトを前記Ｍ個の受信信号にそれぞれ重み付けすることでＭ個の第１の重み付け信号を生成し、前記Ｍ個の第１の重み付け信号に基づいてΣビームを生成するΣビーム生成部と、
    　前記Ｍ個の受信信号にそれぞれ前記Ｍ個のΔウエイトを重み付けすることでＭ個の第２の重み付け信号を生成し、前記Ｍ個の第２の重み付け信号に基づいてΔビームを生成するΔビーム生成部と、
    　前記Σビーム生成部で生成された当該Σビームと前記Δビーム生成部で生成された当該Δビームとの間の比率をモノパルス比として算出するモノパルス比算出部と、
    　ΣビームとΔビームとの間の比率と到来角との間の関係を定める参照用ディスクリカーブと前記モノパルス比とを比較して前記推定値を算出する測角演算部と
    を備えることを特徴とする到来方向推定装置。     An arrival direction estimation apparatus that executes an adaptive monopulse to calculate an estimated value of an arrival angle of an incoming radio wave,
    A correlation matrix generation unit that generates a correlation matrix based on M received signals respectively obtained from outputs of M (M is an integer of 2 or more) antenna elements;
    A ウ エ イ ト weight calculating unit that calculates M ウ エ イ ト weights respectively corresponding to the M received signals using the correlation matrix;
    A Δ weight calculation unit that calculates M Δ weights respectively corresponding to the M received signals by executing a power minimization method using the M ウ エ イ ト weights and two constraint conditions;
    The に beam generating M first weighting signals by weighting the M Σ weights respectively to the M received signals, and generating Σ beams based on the M first weighting signals A generation unit,
    Generating a second M weighted signal by weighting each of the M received signals with the M Δ weights, and generating a Δ beam based on the M second weighted signals A generation unit,
    A monopulse ratio calculation unit which calculates a ratio between the Σ beam generated by the Σ beam generation unit and the Δ beam generated by the Δ beam generation unit as a monopulse ratio;
    A reference discriminator for determining a relationship between a ratio between Σ beam and Δ beam and an arrival angle, and an angle calculation unit for calculating the estimated value by comparing the monopulse ratio with the reference pulse curve Arrival direction estimation device.
  2. 　請求項１記載の到来方向推定装置であって、
    　前記２つの拘束条件のうちの第１の拘束条件は、前記アダプティブモノパルスを実行せずに通常のモノパルス測角を実行して得られる第１のディスクリカーブと前記アダプティブモノパルスを実行して得られる第２のディスクリカーブとが、前記アレイアンテナの中心角で共に零の値をとるとの条件であり、
    　前記２つの拘束条件のうちの第２の拘束条件は、前記第１のディスクリカーブと前記第２のディスクリカーブとが、前記アレイアンテナの中心角で等しい傾きを有するとの条件である、
    ことを特徴とする到来方向推定装置。     The arrival direction estimation apparatus according to claim 1, wherein
    The first constraint condition among the two constraint conditions is a first discriminator curve obtained by executing a normal monopulse angle measurement without executing the adaptive monopulse and a first constraint condition obtained by executing the adaptive monopulse. And the condition that a value of zero is taken at the central angle of the array antenna.
    The second constraint condition of the two constraint conditions is a condition that the first and second discriminative curves have equal inclination at the central angle of the array antenna.
    An arrival direction estimation apparatus characterized in that.
  3. 　請求項１または２記載の到来方向推定装置であって、前記Σウエイト算出部は、前記相関行列を用いた電力最小化法を実行することにより前記Ｍ個のΣウエイトを算出することを特徴とする到来方向推定装置。 3. The arrival direction estimation apparatus according to claim 1, wherein the Σ weight calculation unit calculates the M Σ weights by executing a power minimization method using the correlation matrix. Arrival direction estimation device.
  4. 　請求項１または２記載の到来方向推定装置であって、
    　ヌル幅調整用のテーパー行列を算出するテーパー行列生成部をさらに備え、
    　前記相関行列生成部は、前記相関行列に前記テーパー行列を作用させることで修正された相関行列を生成し、
    　前記Σウエイト算出部は、当該修正された相関行列を用いて、前記Ｍ個のΣウエイトを算出することを特徴とする到来方向推定装置。     The arrival direction estimation apparatus according to claim 1 or 2, wherein
    And a taper matrix generation unit that calculates a taper matrix for null width adjustment,
    The correlation matrix generation unit generates a correlation matrix corrected by applying the taper matrix to the correlation matrix,
    3. The arrival direction estimation apparatus according to claim 1, wherein the Σ weight calculation unit calculates the M Σ weights using the corrected correlation matrix.
  5. 　請求項４記載の到来方向推定装置であって、
    　前記ヌル幅調整用のパラメータ設定値を前記テーパー行列生成部に供給するパラメータ設定部をさらに備え、
    　前記テーパー行列生成部は、前記アンテナ素子の位置座標の情報を前記パラメータ設定値として用いて前記テーパー行列の各成分を算出することを特徴とする到来方向推定装置。     The arrival direction estimation apparatus according to claim 4, wherein
    It further comprises a parameter setting unit that supplies the parameter setting value for the null width adjustment to the taper matrix generation unit,
    The arrival direction estimation apparatus, wherein the taper matrix generation unit calculates each component of the taper matrix using information of position coordinates of the antenna element as the parameter setting value.
  6. 　請求項１または２記載の到来方向推定装置であって、
    　前記Ｍ個のアンテナ素子を含むアレイアンテナと、
    　前記Ｍ個のアンテナ素子の出力を前記Ｍ個の受信信号に変換する受信部と
    をさらに備えることを特徴とする到来方向推定装置。     The arrival direction estimation apparatus according to claim 1 or 2, wherein
    An array antenna including the M antenna elements;
    And a receiving unit configured to convert the outputs of the M antenna elements into the M received signals.
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