JP2005121420A - Radar system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for estimating precisely the number of target signals included in a reception signal, without increasing the number of pulse pits even when an S/N ratio is low, and to provide a calculation means for a transmission beam-directive direction based on a plurality of angle measured results, in a radar system. <P>SOLUTION: This system is provided with a receiver part for receiving arrival waves such as the target signals, a phase detecting part for obtaining the target reception signals from an intermediate frequency signal, a correlation matrix calculating means for calculating a correlation matrix about the target reception signals to be output, a target number estimating means for outputting the number of estimated targets based on the correlation matrix, the transmission beam-directive direction and an array manifold, a hyper-resolution angle measuring means for outputting a target measured angle value based on a hyper-resolution algorithm from the correlation matrix, the number of the estimated targets and the array manifold, a transmission beam-directive direction calculating means for calculating the next transmission beam-directive direction for the target and a beam formation weight setting value therefor, based on a target measured angle value, and for outputting the target measured angle value and the beam formation weight setting value, and the like. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention receives a reflected wave with respect to a transmission beam with an array antenna, estimates the target number included in the received signal, measures the direction of arrival, and determines the direction of the next transmission beam based on the angle measurement result. The present invention relates to a radar apparatus.

  As a means for estimating the target number included in a received signal in a conventional radar apparatus, a method using AIC (Akaike Information Criteria) or MDL (Minimum Description Length) (hereinafter referred to as AIC / MDL method) is known. (For example, refer nonpatent literature 1.).

M.Wax, T.Kailath, “Detection of Signals by Information Theoritic Criteria”, IEEE Trans. On Acoustics, Speech, and Signal Processing, Vol.ASSP-33, No.2, Apr. 1985

  In addition, as for the means for calculating the directivity direction of the next transmission beam based on the angle measurement result, when the angle measurement result is one, the direction is generally set as the directivity direction. Has been reported in the patent literature and the non-patent literature so far.

  In the AIC / MDL method described above, an erroneous estimation result may be shown when the signal to noise power (SN) ratio of the target signal from the radar is low. For this reason, the accuracy of the estimation results has been increased by increasing the number of pulse hits and increasing the SN ratio for the beam direction of interest. However, since the number of pulse hits in one beam direction is increased, it is necessary to reduce the number of pulse hits used in other beam directions, and there is a problem that the detection distance is reduced or the tracking accuracy is deteriorated.

  The present invention solves the above-described problem, and the target signal number included in the received signal from the transmission beam directing direction can be increased without increasing the number of pulse hits even when the SN ratio is low. The purpose is to obtain a more accurate estimation method than the MDL method.

  The radar apparatus of the present invention receives a reflected wave with respect to a transmission beam by an array antenna, estimates a target signal number, measures the direction of arrival of each by a monopulse angle measuring means, and determines the next transmission beam based on the angle measurement result. In the radar apparatus that determines the directivity direction of the beam, the directivity direction of the next transmission beam with respect to the target and the beamforming weight setting value for the target beam are calculated based on the target angle value, and the transmission beam pointing direction and the beamforming weight setting value are calculated. Output transmit beam pointing direction calculation means and the estimated target number is input. When the target number is 1, a selection signal for selecting monopulse angle measuring means is output, and when it is 2 or more, other selection signals are output. The angle measuring means selecting means for outputting the estimated target number, and the phase for calculating and outputting the correlation matrix related to the target received signal in the range bin corresponding to the target detection range bin number. The matrix calculation means, the array manifold that records the antenna pattern data of each antenna constituting the array antenna, and other selection signals from the angle measurement means selection means are input, and the correlation matrix and measurement from the correlation matrix calculation means are input. Super-resolution angle measuring means for outputting a target angle value based on the super-resolution algorithm from the estimated number of angles from the angle means selecting means and the array manifold to the transmission beam pointing direction calculating means and the monopulse angle measuring means, and the correlation matrix And a target number estimating means for outputting an estimated target number to the angle measuring means selecting means based on the MEP method from the correlation matrix calculated by the calculating means, the transmission beam pointing direction, and the array manifold.

  Even when the SN ratio of the target signal is low, the target signal number is estimated with high accuracy without increasing the number of pulse hits. In addition, when there are a plurality of estimated target numbers, the transmission beam pointing direction calculation means that sets the transmission beam pointing direction as an average value of a plurality of angle measurement values enables a radar apparatus in which the detection distance is not reduced or the tracking accuracy is not deteriorated. Become.

Embodiment 1 FIG.
1 is a block diagram showing Embodiment 1 of the present invention.
In FIG. 1, 1 is a controller that outputs a transmission frequency setting value and a transmission timing trigger, 2 is a frequency oscillator that generates a continuous wave based on the transmission frequency setting value, and 3 is the continuous wave based on the transmission timing trigger. Transmitter for outputting pulse-modulated transmission pulse, 4 is a phase shifter for performing a phase shift operation based on a beam forming weight setting value to be described later with respect to the transmission pulse, 5 is a transmission / reception switch for switching transmission and reception, and 6 is a transmission / reception switching An array antenna composed of a plurality of antennas for transmitting incoming pulses such as target signals, clutter reflected waves, jamming waves, etc., through the transmission / reception switcher. A receiver unit for frequency-converting the input incoming wave into an intermediate frequency signal, and 8 a baseband by A / D conversion and phase detection of the intermediate frequency signal from the receiver unit. And a phase detector 9 for outputting the received signal in the band, and performing a clutter suppression to suppress the clutter reflected wave included in the received signal from the phase detector, and outputting the received signal after the clutter suppression A clutter suppression unit 1 performs interference wave suppression to suppress the interference wave signal included in the reception signal after clutter suppression and outputs a target reception signal, and 11 indicates the target reception signal and a beam described later. Σ beam and a form wait setting value, delta _AZ beam, beam combining means for outputting a delta _EL beam 12 performs the integration of the pulses hit direction to three receive beams of the, integration after Σ beam, after integration delta _An inter-pulse integrator 13 for outputting an _AZ beam and a post-integral Δ _EL beam, and 13 performs target detection by threshold processing on the post-integration Σ beam, and if there is target detection, a target detection range A signal detection means 14 for outputting a bin number, when there is an input of a selection signal described later, from the integrated Σ beam and the integrated _ΔAZ beam and from the integrated Σ beam and the integrated Δ _EL beam. Monopulse angle measurement means for obtaining an azimuth angle and an elevation angle by monopulse angle measurement and outputting them together as a target angle measurement value, 15 for the target received signal in the range bin corresponding to the target detection range bin number A correlation matrix calculating means 16 for calculating a correlation matrix and outputting it is based on the MEP (Radar Signal Number Detection using Multiple Eigenbean Pattern) method described later from the correlation matrix, a transmission beam pointing direction described later and an array manifold described later. The target number estimating means 1 and 17 for outputting the estimated target number receive the estimated target number as an input. A selection signal for selecting the angle measuring means, and in the case of 2 or more, an angle measuring means selecting means for outputting a selection signal for selecting a super-resolution angle measuring means to be described later and the estimated target number; When there is a signal input, super-resolution angle measuring means 1 and 19 for outputting a target angle value based on a super-resolution algorithm from the correlation matrix, the estimated target number, and an array manifold described later constitute the array antenna. An array manifold 20 in which antenna pattern data of each antenna is recorded, 20 calculates a directing direction of the next transmission beam with respect to the target and a beam forming weight setting value for the target based on the target angle measurement value, and sets the transmission beam directing direction and beam This is a transmission beam pointing direction calculation means 1 that outputs a formation weight setting value.

FIG. 2 is a configuration diagram of the target number estimating means 1 according to the first embodiment of the present invention.
In FIG. 2, reference numeral 21 denotes an eigenvalue / eigenvector calculating means for obtaining the eigenvalue / eigenvector by inputting the correlation matrix, and 22 is an eigenvalue / eigenvector calculating means for outputting the eigenvector. MEP value calculation means 23 for outputting MEP value gap calculation means for receiving the MEP value as input, estimating the target number from the maximum value of the gap (difference) between adjacent MEP values, and outputting it.

The operation will be described below.
First, the controller 1 outputs a transmission frequency set value and a transmission timing trigger.
The frequency oscillator 2 generates and outputs a continuous wave based on the transmission frequency set value, and the transmitter 3 generates and outputs a transmission pulse that is pulse-modulated based on the continuous wave and the transmission timing trigger. The transmission pulse passes through the phase shifter section 4 and the transmission / reception switch 5 in which the phase shift is set based on the beam forming weight setting value described later, and is radiated into the air from the array antenna 6.
Such transmission is performed for a desired number of pulse hits at an appropriate pulse repetition interval.

Subsequently, reception described below is performed, and reception is performed for each range bin. Now, the target signal of the K-wave, the interference wave of K _J wave, and clutter reflected signal incoming direction is spread angularly is assumed to come. However, these signals are not completely correlated with each other. Further, it is assumed that there is a relationship as shown in Expression (1) among the number M of antennas constituting the array antenna 6, the target signal number K, and the interference wave number K _J.

A target signal, an interference wave, and a clutter reflected signal that are incoming waves to the array antenna 6 are frequency-converted to an intermediate frequency signal in a receiver unit 7 composed of M receivers via a transmission / reception switch 5. The signal is input to a phase detector 8 composed of M phase detectors and converted into a received signal in the baseband.
Since the phase detector 8 performs A / D conversion, the received signal is a digital signal.

Subsequently, the received signal is input to the clutter suppression unit 9 to suppress the clutter reflection signal included in the received signal.
The clutter suppression means constituting the clutter suppression unit performs clutter suppression according to the principle of the FIR digital filter. For example, according to Merril I. Skolnik et al., “Radar Handbook” (McGraw Hill, 1989), It has been shown that reflected waves from fixed or low-speed moving clutter on the sea surface or the like can be suppressed.
In this way, the clutter suppression unit 9 outputs a clutter-suppressed received signal after clutter suppression. Now, a received signal after clutter suppression in a certain focused range bin is expressed as shown in Equation (2).

Since the received signal X _J (n) after clutter suppression includes thermal noise in addition to the target signal and the interference wave, they are expressed as in equations (3) to (5), respectively.

Using the above equations (3) to (5), the clutter-suppressed received signal X _J (n) can be expressed as equation (6).

_{Hereinafter, θ 1, ..., θ K} -1, a (θ 1), ..., it is the same for _{a (θ K-1),} 0 ψ relates _{disturbance, ..., ψ KJ-1,} a (ψ 0 ), ..., a (ψ _KJ-1 ).
Furthermore, A _s = [a (ψ ₀ ) a (ψ ₁ )… a (ψ _K-1 )] ^T , A _J = [a (ψ ₀ ) a (ψ ₁ )… a (ψ _KJ-1 )] ^{If T} , then equation (6) can be expressed as equation (7).

Subsequently, the clutter-suppressed received signal X _J (n) is input to the jamming wave suppression unit 10 to suppress the jamming wave included in the signal.
In the interference wave suppression means, interference wave suppression is performed based on the principle of directing the null of the received beam pattern with respect to the arrival direction of the interference wave. For example, according to Merril I. Skolnik et al. It has been shown that jamming waves coming from the sidelobe direction can be suppressed.
In this way, the target reception signal X (n) in which the interference wave is suppressed is output from the interference wave suppressing means 10. The signal can be expressed as in equation (8).

Subsequently, the target received signal is input to the beam combining unit 11, and the Σ beam, Δ beam, and Δ _EL beam are changed based on the beam forming weight setting value that is an output from the transmission beam directing direction calculating unit 1 (20) described later. Synthesize.
When the beam forming weight is expressed as in Expression (9), beam synthesis is expressed as Expressions (10) to (12).

However, D _AZ is a diagonal matrix and the diagonal term is 1 or -1.
The diagonal element number (m, m) (m = 0,1, ..., M-1) of the matrix corresponds to the number m of the antennas constituting the array antenna 6, and the antenna is divided symmetrically. It is 1 (or -1) when it corresponds to the left opening of the array antenna opening surface, and -1 (or 1) when it corresponds to the right opening. The same applies to D _EL , which is 1 (or -1) if it corresponds to the upper opening of the array antenna aperture divided vertically, and -1 (or 1) if it corresponds to the lower opening. It becomes.

Subsequently, sigma beam Σ (n), Δ _AZ beam Δ _AZ (n), Δ _EL beam delta _EL (n) is input to the pulse between the integration unit. The inter-pulse integration means coherently integrates the target reception signals arranged in the pulse hit direction with respect to the direction. The integration improves the SN ratio, especially for Σ (n). For example, Merril I. Skolnik et al., “Radar Handbook” (McGraw Hill, 1989) shows that the SN ratio improves N times. Yes. Coherently integrated after each input signal is integrated sigma beam sigma, integration after delta _AZ beam delta _AZ, is integrated after delta _EL beam delta _EL next output.

  Subsequently, the integrated Σ beam Σ is input to the signal detection means, and after amplitude detection, threshold processing is performed. If the amplitude value exceeds the threshold, it is verified that there is signal detection, and the range bin number is output. Is done. For example, as shown in “Radar Handbook” (McGraw Hill, 1989) by Merril I. Skolnik et al., The threshold processing sets a threshold value that maintains a certain false alarm probability and satisfies a desired detection probability.

On the other hand, after the integration sigma beam sigma, integration after delta _AZ beam delta _AZ, integration after delta _EL beam delta _EL is input to monopulse angle measuring means, if there is a selection signal from the angle measuring unit selection means 17 will be described later, the integration Using the post-Σ beam Σ and post-integration Δ _AZ beam Δ _AZ , the target azimuth angle measurement value θ _0AZ based on the principle of monopulse angle measurement is obtained, and the post-integration Σ beam Σ, post-integration Δ _EL beam Δ _EL Thus, the measured angle value θ _0EL of the target elevation angle based on the principle of monopulse angle measurement is obtained, and is collectively output as the target angle value θ ₀ = [θ _0AZ , θ _0EL ] ^T.
The principle of monopulse angle measurement is shown, for example, in “Radar Handbook” (McGraw Hill, 1989) by Merril I. Skolnik et al.

  When the target detection range bin number is input from the signal detection unit 13 described above, the correlation matrix calculation unit 15 calculates the correlation matrix represented by the equation (13) using the target received signal vector of the corresponding range bin number. And output.

The correlation matrix is input to the target number estimating means 1 (16) and input to the eigenvalue / eigenvector calculating means 21 inside the means. At this time, since the correlation matrix is clearly a Hermitian matrix, its eigenvalue is a real number, and eigenvectors are known to be orthogonal to each other.
Here, we arranged eigenvalues in descending order, and outputs the corresponding eigenvector e _m respectively.

In MEP value calculating means 22, and the eigenvector e _m, transmission beam pointing direction of the transmission below the beam pointing direction calculating unit 1 (20), and by using the array manifold 19, the MEP value shown in Equation (14) Calculate and output.

However, ψ _beamwidth indicates an appropriate angle range centered on the transmission beam directing direction, and ψ is an angle existing in the range. An appropriate angle range is an angle range where the target signal arrives, for example, a transmission beam width. a (ψ) is an array manifold for the angle ψ.

The MEP value shown in Expression (14) will be specifically described.
The equation is the eigenvector e _m beam pattern and antenna weights _{^{| a H (ψ) e m}} | thinking ^2, can be interpreted as the integral value of the portion that fits in the angular range [psi _beamwidth. Here, if the eigenvector e _m corresponding to the noise eigenvalues, since the ^{_{a H (ψ k) e m}} = 0, the beam pattern | k pieces in an angular range [psi _beamwidth in ^{2 | a H (ψ) e} m Will be formed.

On the other hand, if the eigenvector e _m corresponds to the target characteristic value, since the ^{_{a H (ψ k) e m}} ≠ 0, in the direction in which the k null the at least above is formed null is not formed. The MEP value represents the feature of the beam pattern | a ^H (ψ) e _m | ² resulting from such a difference in eigenvalue as an integral value in the angle range ψ _beamwidth . That, MEP value when eigenvector e _m corresponds to the target characteristic value increases, will have a smaller tendency when corresponding to the noise eigenvalues.
Therefore, as described later, the target number can be estimated by using the gap (difference) between adjacent MEP values.

Next, the MEP value obtained from the equation (14) is input to the MEP value gap calculation means 23. Here, a gap (difference) between adjacent MEP values is obtained, and K _estimated so as to satisfy Expression (15) is output as the estimated target number.

  FIG. 3 shows a result of comparing the above-described MEP method, AIC / MDL method, and target number estimation accuracy by computer simulation. Details of the simulation conditions are shown in the figure. The simulation is for the case of target number 2, but it can be seen that the target number is correctly estimated even at a lower SN ratio than the AIC / MDL method.

Subsequently, the estimated target number K _estimated is input to the angle measuring means selecting means 17. When K _estimated = 1, a selection signal for selecting the monopulse angle measuring means 14, and when K _estimated > 1, super resolution angle measuring described later. A selection signal for selecting the means 18 is output.

The super-resolution angle measuring means 1 (18) receives the selection signal from the angle-measuring means selecting means 17 and inputs the estimated target number K _estimated , the correlation matrix Rxx, and the array manifold a (θ) as super-resolution. A plurality of targets are separated and measured by target angle measurement based on an algorithm, and target angle measurement values θ ₀ ,..., Θ _K−1 are output.

  For example, MUSIC angle measurement (ROSchmidt, “Multiple Emitter Location and Signal Parameter Estimation”, IEEE Trans. On Antennas and Propagation, Vol. APS-34, no. 3, Mar 1986), MLE angle measurement (I. Ziskind, M. Wax, “Maximum Likelihood Localization of Multiple Sources by Alternating Projection”, IEEE Trans. On Acoustics, Speech, and Signal Processing, Vol. 36, No. 10, Oct. 1988).

Next, the transmission beam pointing direction calculation means 1 (20) calculates the transmission beam pointing direction according to the equation (16) based on the input target angle value _k .

  That is, as shown in Expression (16), the average value of the input target angle values is determined as the directing direction of the next transmission beam.

In addition, the beam forming weight W _TX based on the in-phase condition is calculated for the transmission beam directing direction θ _TX and output.

  As described above, in this embodiment, the reflected wave for the transmission beam is received by the array antenna, the target signal number is estimated, the direction of arrival of each is measured, and the next transmission is performed based on the angle measurement result. By configuring a radar device that determines the beam pointing direction and performing the above-mentioned MEP method and the above-described transmission beam pointing direction calculation operation, the number of pulse hits is not increased even when the SN ratio of the target signal is low. In addition, the number of target signals is estimated with high accuracy compared to the AIC / MDL method, and when there are a plurality of estimated target numbers, the transmission beam pointing direction calculation means that sets the transmission beam pointing direction as an average value of a plurality of angle measurement values Can be obtained.

Embodiment 2. FIG.
FIG. 4 is a block diagram showing Embodiment 2 of the present invention.
In the figure, reference numeral 24 denotes a target number for outputting an estimated target number based on a later-described AMS (Radar Signal Number Detection using Inner Product between Eigenbeam Weight of Array Manifold and Observed Signal) method from a correlation matrix, a transmission beam pointing direction, and an array manifold. The portion corresponding to FIG. 1 in the estimation means 2 is denoted by the same reference numeral, and detailed description thereof is omitted.

FIG. 5 is a block diagram of the target number estimating means 2 in the second embodiment of the present invention.
In FIG. 5, 25 is an array manifold correlation matrix calculation means for obtaining and outputting a correlation matrix related to the array manifold from the transmission beam directivity direction and the array manifold, and 26 is the eigenvalue / eigenvector of the array manifold correlation matrix as input. Is an array manifold eigenvalue / eigenvector calculation means 27 for outputting an AMS value from the eigenvector, the transmission beam pointing direction and the array manifold, and is an AMS value calculation means 28 for outputting the AMS value. The AMS value gap calculation means estimates and outputs the target number from the maximum gap between adjacent AMS values. The parts corresponding to those in FIG.

The operation will be described below.
Since the operations other than the target estimation unit 2 (24) are the same as those in the first embodiment, a description thereof will be omitted.

  The array manifold correlation matrix calculation means 25 calculates the array manifold correlation matrix shown in Expression (17) using the transmission beam pointing direction from the transmission beam pointing direction calculation means 1 (20) and the array manifold 19, and outputs the result. To do.

The following array manifold eigenvalue / eigenvector calculation means 26 obtains eigenvalues / eigenvectors related to the array manifold correlation matrix. At this time, since the correlation matrix is obviously a Hermitian matrix, its eigenvalue is a real number, and eigenvectors are known to be orthogonal to each other.
Here, the eigenvalues are arranged in descending order, and the corresponding eigenvectors e ′ _m are output. The eigenvector is called an array manifold eigenvector.

Here, the array manifold eigenvalue / eigenvector obtained from the equation (17) indicates a rank R in which the array manifold correlation matrix is usually low. Therefore, when array manifold eigenvalues are arranged in descending order and attention is paid to the array manifold eigenvalues up to the R-th, the array manifold eigenvector extends a partial space of an incoming wave arriving in the angular range ψ _beamwidth .
This property and interpretation was pointed out in KMBuckley, X.Xu, “Spatial-Spectrum Estimation in a Location Sector”, IEEE Trans. On Acoustics, Speech and Signal Processing, Vol.38, No.11, Nov., 1990. Yes.

Subsequently, the AMS value calculating means 27, by using the above eigenvector e _m and the array manifold eigenvector e _'m, to calculate the AMS value shown in Equation (18), and outputs.

The AMS value shown in Expression (18) will be specifically described.
Of the array manifold eigenvectors e ′ _m , as described above, R are vectors extending the subspace of the target signal. Thus, the vector corresponding to the target signal of the eigenvector e _m is substantially coincides with any of the above R-number of the array manifold eigenvectors is believed that approximately perpendicular to the others.

Therefore, as shown in equation (18), and AMS value the maximum square value when determined all _i ^H e _m 'inner product e and _i' is the eigenvector e _m and all array manifold eigenvector e, sequentially all eigenvectors e _Ask for _m . Thus, AMS value when eigenvector e _m corresponds to the target characteristic value increases, will have a smaller tendency when corresponding to the noise eigenvalues.
Therefore, as described later, the target number can be estimated by using the gap (difference) between adjacent AMS values.

Next, the AMS value obtained according to the equation (18) is input to the AMS value gap calculating means 29. Here, a gap (difference) between adjacent AMS values is obtained, and K _estimated to satisfy Equation (19) is output as the estimated target number.

FIG. 6 shows a result of comparing the above-described AMS method, AIC / MDL method, and target number estimation accuracy by computer simulation. Details of the simulation conditions are shown in the figure.
The simulation is for the case of target number 2, but it can be seen that the target number is correctly estimated even at a lower SN ratio than the AIC / MDL method.

  As described above, in this embodiment, the reflected wave for the transmission beam is received by the array antenna, the target signal number is estimated, the direction of arrival of each is measured, and the next transmission is performed based on the angle measurement result. By configuring the radar device that determines the beam pointing direction, and performing the above-described AMS method and transmission beam pointing direction calculation operation, even when the SN ratio of the target signal is low, without increasing the number of pulse hits, Estimate the number of target signals with higher accuracy than the AIC / MDL method, and when there are multiple estimated target numbers, obtain a transmission beam pointing direction calculation means that uses the transmission beam pointing direction as the average of the multiple angle measurement values. be able to.

Embodiment 3 FIG.
FIG. 7 is a block diagram showing Embodiment 3 of the present invention.
In the figure, reference numeral 29 denotes a correlation matrix as an input, and target number estimation means 3 and 30 for outputting an estimated target number based on the AIC / MDL method are based on the target angle value, and the pointing direction of the next transmission beam with respect to the target and therefore 1 is a transmission beam pointing direction calculation means 2 for calculating the beamforming weight setting value and outputting the beamforming weight setting value. The parts corresponding to those in FIG. .

The operation will be described below.
Since the operations other than the target estimation unit 3 (29) and the transmission beam pointing direction calculation unit 2 (30) are the same as those in the first embodiment, the description thereof will be omitted.

  The target number estimating means 3 (29) receives the correlation matrix and outputs the estimated target number based on the AIC / MDL method. The principle of the AIC / MDL method is described in M.Wax, T.Kailath, “Detection of Signals by Information Theoritic Criteria”, IEEE Trans. On Acoustics, Speech, and Signal Processing, Vol.ASSP-33, No.2, Apr. As shown in 1985.

  The transmission beam directivity direction calculating means 2 (30) is configured to eliminate the output related to the transmission beam directivity direction in the operation of the transmission beam directivity direction calculating means 1 (20).

  As described above, in this embodiment, the reflected wave for the transmission beam is received by the array antenna, the target signal number is estimated, the direction of arrival of each is measured, and the next transmission is performed based on the angle measurement result. By configuring a radar device that determines the beam pointing direction and performing the above-described AIC / MDL method and transmission beam pointing direction calculation operation, when there are a plurality of estimated target numbers, It is possible to obtain a transmission beam pointing direction calculation means that uses an average value of the angle measurement values.

Embodiment 4 FIG.
FIG. 8 is a block diagram showing Embodiment 4 of the present invention.
In the figure, reference numeral 31 denotes a super-resolution angle measuring means 2 for outputting a target angle value and a target power value based on a super-resolution algorithm from a correlation matrix, an estimated target number, and an array manifold when a selection signal is input. 32 calculates the directing direction of the next transmission beam with respect to the target and the beamforming weight setting value for the target based on the target angle measurement value and the target power value, and outputs the transmission beam directing direction and the beamforming weight setting value. The transmission beam directing direction calculating means 3 is provided with the same reference numerals as those in FIG. 1, and the detailed description thereof is omitted.

The operation will be described below.
Since the operations other than the super-resolution angle measuring means 2 (31) and the transmission beam pointing direction calculating means 3 (32) are the same as those in the first embodiment, the description thereof is omitted.

In the super-resolution angle measuring means 2 (31), when the selection signal is inputted from the angle-measuring means selecting means 17, the super-resolution algorithm is inputted with the estimated target number K _estimated , the correlation matrix Rxx, and the array manifold a (ψ) as inputs. Multiple targets are separated and measured by target angle measurement based on. Examples of the super-resolution angle measurement include the above-described MUSIC angle measurement and the above-mentioned MLE angle measurement.
Next, using the measured angle values θ ₀ ,…, θ _K-1 , ROSchmidt, “Multiple Emitter Location and Signal Parameter Estimation”, IEEE Trans. On Antennas and Propagation, Vol. APS-34, no. 3, Mar target power value in the manner shown in 1986 or the like P _0, ..., determine the P _K-1, the measured angle value θ _0, ..., and outputs with θ _K-1.

In the transmission beam pointing direction calculation means, when a plurality of angle measurement results are obtained, there is a problem that the transmission beam pointing direction calculation means based on this is not clear, and the transmission beam pointing direction cannot be determined. The beam pointing direction calculation means 3 (32) calculates the transmission beam pointing direction according to the equation (20) based on the input target angle value θ _k and the target power value P _k .

  That is, as shown in equation (20), the average value of the target angle values weighted by the input target power value is determined as the pointing direction of the next transmission beam.

In addition, the beam forming weight W _TX based on the in-phase condition is calculated for the transmission beam directing direction θ _TX and output.

  As described above, in this embodiment, the reflected wave for the transmission beam is received by the array antenna, the target signal number is estimated, the direction of arrival of each is measured, and the next transmission is performed based on the angle measurement result. By configuring a radar device that determines the beam pointing direction and performing the above-mentioned MEP method and the above-described transmission beam pointing direction calculation operation, the number of pulse hits is not increased even when the SN ratio of the target signal is low. In addition, the number of target signals is estimated with higher accuracy than the AIC / MDL method, and when there are multiple estimated target numbers, the average of the target angle values obtained by weighting the transmit beam pointing direction with multiple target power values It is possible to obtain a transmission beam directivity direction calculation means as a value.

Embodiment 5 FIG.
FIG. 9 is a block diagram showing Embodiment 5 of the present invention.
In this figure, the parts corresponding to those in FIG. 4 are denoted by the same reference numerals, detailed description thereof is omitted, and the super-resolution angle measuring means 2 (31) and the transmission beam pointing direction calculating means 3 (32) are shown in FIG. Since the same reference numerals are used, detailed description thereof is omitted.

  The operation will be described below. Since the operations other than the super-resolution angle measuring means 2 (31) and the transmission beam pointing direction calculating means 3 (32) are the same as those in the second embodiment, the description thereof is omitted. In addition, the operations of the super-resolution angle measuring means 2 (31) and the transmission beam pointing direction calculating means 3 (32) are the same as those in the fourth embodiment, and thus will be omitted.

  As described above, in this embodiment, the reflected wave for the transmission beam is received by the array antenna, the target signal number is estimated, the direction of arrival of each is measured, and the next transmission is performed based on the angle measurement result. By configuring the radar device that determines the beam pointing direction, and performing the above-described AMS method and transmission beam pointing direction calculation operation, even when the SN ratio of the target signal is low, without increasing the number of pulse hits, Estimate the number of target signals with higher accuracy than the AIC / MDL method, and if there are multiple estimated target numbers, the average value of the target angle values obtained by weighting the transmission beam pointing direction with multiple target power values Thus, it is possible to obtain a transmission beam pointing direction calculation means.

Embodiment 6 FIG.
FIG. 10 is a block diagram showing Embodiment 6 of the present invention.
In the figure, reference numeral 33 denotes a transmission beam that calculates the direction of the next transmission beam with respect to the target and the beamforming weight setting value therefor based on the target angle value and the target power value, and outputs the beamforming weight setting value. The directivity direction calculation means 4, parts corresponding to those in FIG. 7 are assigned the same reference numerals, detailed description thereof is omitted, and the super-resolution angle measuring means 2 (31) corresponds to the same reference numerals in FIG. 8. Therefore, the detailed description is abbreviate | omitted.

The operation will be described below.
Since the operations other than the super-resolution angle measuring means 2 (31) and the transmission beam pointing direction calculating means 3 (32) are the same as those in the third embodiment, the description thereof is omitted. Further, the operation of the super-resolution angle measuring means 2 (31) is the same as that of the fourth embodiment, so that the description thereof is omitted. The transmission beam directivity direction calculation means 4 (34) eliminates the output related to the transmission beam directivity direction in the operation of the transmission beam directivity direction calculation means 3 (33).

  As described above, in this embodiment, the reflected wave for the transmission beam is received by the array antenna, the target signal number is estimated, the direction of arrival of each is measured, and the next transmission is performed based on the angle measurement result. By configuring a radar apparatus that determines the beam directing direction and performing the above-described AIC / MDL method and transmission beam directing direction calculation operation, when there are a plurality of estimated target numbers, It is possible to obtain a transmission beam pointing direction calculation means that takes the average value of the target angle values weighted by the target power value.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the radar apparatus which shows Embodiment 1 of this invention. It is a block diagram of the target number estimation means 1 in Embodiment 1 of this invention. It is a figure which shows the performance of the target number estimation means 1 in Embodiment 1 of this invention. It is a block diagram of the radar apparatus which shows Embodiment 2 of this invention. It is a block diagram of the target number estimation means 2 in Embodiment 2 of this invention. It is a figure which shows the performance of the target number estimation means 2 in Embodiment 2 of this invention. It is a block diagram of the radar apparatus which shows Embodiment 3 of this invention. It is a block diagram of the radar apparatus which shows Embodiment 4 of this invention. It is a block diagram of the radar apparatus which shows Embodiment 5 of this invention. It is a block diagram of the radar apparatus which shows Embodiment 6 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Controller, 2 Frequency oscillator, 3 Transmitter, 4 Phase shifter part, 5 Transmission / reception switcher, 6 Array antenna, 7 Receiver part, 8 Phase detection part, 9 Clutter suppression part, 10 Interference wave suppression means, 11 Beam Combining means, 12 inter-pulse integrator, 13 signal detecting means, 14 monopulse angle measuring means, 15 correlation matrix calculating means, 16 target number estimating means 1, 17 angle measuring means selecting means, 18 super-resolution angle measuring means 1, 19 array Manifold, 20 Transmit beam pointing direction calculation means 1, 21 Eigenvalue / eigenvector calculation means, 22 MEP value calculation means, 23 MEP value gap calculation means, 24 Target number estimation means 2, 25 Array manifold correlation matrix calculation means, 26 Array manifold eigenvalue -Eigenvector calculation means, 27 AMS value calculation means, 2 AMS value gap calculation means, 29 a target-count estimating unit 3, 30 transmission beam pointing direction calculating unit 2, 31 super-resolution angle measuring unit 2, 32 transmission beam pointing direction calculating means 3, 33 transmission beam pointing direction calculating unit 4.

Claims (6)

The reflected wave for the transmitted beam is received by the array antenna, the target number of signals is estimated, the direction of arrival of each is measured by monopulse or super-resolution angle measuring means, and the direction of the next transmitted beam is determined based on the angle measurement result. In the radar device to determine,
Based on the target angle measurement value, a transmission beam pointing direction calculating means for calculating a direction of the next transmission beam with respect to the target and a beam forming weight setting value therefor, and outputting a transmission beam pointing direction and a beam forming weight setting value;
When the estimated target number is input, if the target number is 1, a selection signal for selecting the monopulse angle measuring means is output, and if it is 2 or more, the other selection signal and the estimated target number are output. Means selection means;
A correlation matrix calculating means for calculating and outputting a correlation matrix related to the target received signal in the range bin corresponding to the target detection range bin number;
An array manifold that records antenna pattern data of each antenna constituting the array antenna;
Other selection signals are input from the angle measurement means selection means, and the target angle measurement based on the super resolution algorithm is performed based on the correlation matrix from the correlation matrix calculation means, the estimated target number from the angle measurement means selection means, and the array manifold. Super-resolution angle measuring means for outputting a value to the transmission beam pointing direction calculating means and the monopulse angle measuring means;
A target number estimating means for outputting an estimated target number to the angle measuring means selecting means based on the MEP method from the correlation matrix calculated by the correlation matrix calculating means and the transmission beam pointing direction and the array manifold;
A radar apparatus comprising: 2. The radar apparatus according to claim 1, wherein said target number estimating means uses AMS value calculating means for obtaining and outputting an AMS value from a target eigenvector, a transmission beam pointing direction, and an array manifold. 2. The radar apparatus according to claim 1, wherein the target number estimation means receives the correlation matrix and outputs an estimated target number based on the AIC / MDL method. As the target number estimating means, the estimated target number is output to the angle measuring means selecting means based on the MEP method from the correlation matrix, the transmission beam pointing direction and the array manifold, and the correlation matrix and the estimation are estimated as the super resolution angle measuring means. The radar apparatus according to claim 1, wherein a target angle measurement value and a target power value based on a super-resolution algorithm are output from the target number and the array manifold. 5. The radar apparatus according to claim 4, wherein as the target number estimating means, an AMS value calculating means for obtaining and outputting an AMS value from an eigenvector, a transmission beam pointing direction, and an array manifold is used. The radar apparatus according to claim 4, wherein the target number estimating means outputs an estimated target number based on an AIC / MDL method.

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