CN110196415A - A kind of wide null Beamforming Method based on compensation Antenna error - Google Patents

Abstract

A wide null-notch beamforming method based on compensating antenna pattern errors. The present invention relates to wide null notch beamforming methods. The purpose of the present invention is to solve the problem that the traditional clutter suppression algorithm cannot suppress the sea clutter broadened by the movement of the ship under the background of the antenna pattern error. The process is as follows: 1: Obtain the antenna pattern error data corresponding to each angle of the antenna affected by the error through active correction; 2: Perform pulse compression and coherent accumulation processing on the echo data of the shipboard high-frequency ground wave radar to obtain the channel × Doppler × distance three-dimensional spectral data; three: get the weight coefficient of the normalized modified orthogonal weighting method; four: get the weight coefficient of the wide zero-notch beamforming method; five: use the wide zero-notch beamforming method weight coefficient to the three-dimensional The spectral data is processed to obtain angle × Doppler × distance three-dimensional spectral data after sea clutter is suppressed. The invention is used in the field of shipboard high-frequency ground wave radar signal processing.

Description

A Wide Null Notch Beamforming Method Based on Compensating Antenna Pattern Error

technical field

The invention relates to the field of shipboard high-frequency ground wave radar signal processing, and can be used for sea clutter suppression of shipboard ground wave radar in the background of antenna pattern error.

Background technique

Shipborne high-frequency ground wave radar is a new system radar with a working frequency band of 3MHz-30MHz. Compared with conventional radars such as microwave radars, it has over-the-horizon detection of targets below the horizon, anti-stealth, long warning time, and anti-anti-radiation missiles. , equipment stability, strong anti-jamming ability and other advantages, currently play an important role in the military field of all countries in the world.

For shipboard high-frequency ground wave radar, the movement of the ship platform will cause the broadening of the first-order sea clutter spectrum, which will make the slower ship target be affected by the broadening spectrum and be submerged in the sea clutter, resulting in the inability to detect the target information to make accurate estimates. Since the first-order sea clutter spectrum is related to the speed of the ship, relatively speaking, the direction of the sea clutter can be inferred from the speed of the ship, so that the problem can be transformed into a method of suppressing the clutter with a known position. question. In response to this problem, domestic scholars have carried out extensive research. Xie Junhao. Research on target detection and evaluation of shipborne high-frequency ground wave radar [D]. Harbin Institute of Technology, 2001. Introduced the orthogonal weighting method (Orthogonal Weighting, OW ), so as to suppress the first-order sea clutter; Sun M, Xie J, Hao Z, et al.Target Detection and Estimation for Shipborne HFSWR Based on Oblique Projection[C]//2012 11th International Conference on Signal Processing (ICSP 2012). In 0., the oblique projection algorithm (Oblique Projection, OP) was introduced to address the shortcomings of the orthogonal weighting method, which can retain the information of the target signal to a greater extent while suppressing the fixed azimuth clutter.

For the traditional shipboard high-frequency ground wave radar, due to the limitation of the antenna placement and the actual environment, there will be interference of the antenna pattern error, which will cause the antenna pattern to be distorted, and the work cannot be completed normally. Traditional clutter suppression algorithms, such as orthogonal weighting method and oblique projection algorithm, will deteriorate in the presence of antenna pattern errors, and cannot fully suppress the broadened sea clutter of submerged ships. In addition, since the amplitude and phase characteristics of the antenna and channel change slowly with the growth of use time, the actual error of the antenna array may deviate from the initial error measurement value, so the correction of the antenna pattern error further increases the difficulty.

When the antenna array is arranged as a uniform linear array along both sides of the ship's side, and the antenna is not affected by the pattern error, the pattern synthesized by the antenna array (including nulls) is symmetrical with respect to the antenna array. At this time, the radar array can simultaneously suppress the sea clutter from both sides of the antenna array. And when the antenna pattern error exists, the pattern synthesized by the antenna array is no longer symmetrical about the antenna array. The traditional null formation algorithm can only suppress the clutter source on one side of the antenna, while the clutter on the other side enters the antenna and affects the detection.

Array errors have a non-negligible impact on the performance of array antennas. At present, the research focus of scholars from various countries is to correct and analyze the array position error and mutual coupling error, but there are few studies on the correction of the most common antenna pattern error in actual engineering. The method of correcting the map error can suppress the broadened first-order sea clutter in the shipboard high-frequency ground wave radar.

Contents of the invention

The purpose of the present invention is to solve the problem that the traditional clutter suppression algorithm cannot suppress the sea clutter broadened due to the movement of the ship under the background of the antenna pattern error, and to provide a wide range based on the compensation of the antenna pattern error. Zero notch beamforming method.

A specific process of a wide null-notch beamforming method based on compensating antenna pattern errors is as follows:

Step 1: Obtain the antenna pattern error data of each angle corresponding to the antenna affected by the error through active correction, denoted as r(θ);

Step 2: Perform pulse compression and coherent accumulation processing on the echo data of the shipboard high-frequency ground wave radar to obtain channel × Doppler × range three-dimensional spectrum data, which is recorded as CDR;

Step 3: Based on the error data r(θ) obtained in step 1, correct the original array steering vector (array steering vector without error) to obtain the disturbed projection matrix Based on the disturbed projection matrix Get the normalized modified orthogonal weighting method weight coefficient The specific process is:

Step 31: The first-order Bragg frequency is deduced from the principle of Bragg resonance scattering and the principle of deep water dispersion:

Among them, f _B is the Bragg frequency, Bragg frequency is the Bragg frequency, f ₀ is the radar operating frequency, and its unit is MHz;

Step 32: Through the three-dimensional spectral data CDR obtained in step 2, find the Doppler frequency f _d corresponding to the Doppler unit, and obtain the azimuth θ _i of the sea clutter corresponding to f _d :

Among them, v _p is the moving speed of the shipboard platform, θ _i ∈ [0,2π];

Step 33: The array steering vector a(θ _i ) corresponding to sea clutter in azimuth θ _i is:

Step 3 and 4: Use the antenna pattern error data r(θ _i ) obtained in step ₁ to construct the corrected array steering vector

Wherein, ο represents the Hadamard product; r (θ _i ) is the antenna pattern error data of the azimuth θ _i of the sea clutter corresponding to the antenna affected by the error;

Step 3 and 5: Using the Corrected Array Steering Vectors Construct the disturbed projection matrix

Among them, I _M is the unit matrix whose order is the number of array elements M, and the superscript H represents the conjugate transpose;

Step 36: Utilize the disturbed projection matrix Get the weight coefficient of the normalized modified orthogonal weighting method corresponding to the sea clutter with the azimuth θ _i

Among them, s(θ) is the scanning cycle vector, which plays the role of scanning all angles by traversing θ(0°-360°);

Step 37: By traversing θ _i , obtain the normalized weight coefficients of the modified orthogonal weighting method corresponding to all sea clutter

Step 4: Set the width of the wide null trap to Δθ, reconstruct K null traps within Δθ near the clutter orientation θ _i , and use the corrected steering vector corresponding to the reconstructed null trap Instead of the steering vector corrected in step 3 And according to the method in step 3, the weight coefficient W of the wide null-notch beamforming method is obtained; the specific process is:

Step 41: Find the sea clutter azimuth θ _i corresponding to Step 32, set the width of wide nulls to Δθ, the number of reconstructed nulls after improvement is K, and construct the angle corresponding to the improved nulls:

Among them, θ _k is the angle corresponding to the kth null trap after improvement;

Step 42: Use the K angles obtained in Step 41 to construct the corresponding ideal array steering vector:

Step 43: Construct the corrected array steering vector

Wherein, r(θ _k ) is the antenna pattern error data of the θ _kth angle corresponding to the antenna affected by the error;

Step 44: Utilize the Corrected Array Steering Vectors Construct the projection matrix J corresponding to the wide null notch beamforming method:

in, is the modified array-steering vector matrix,

Step 4 and 5: Use the projection matrix J corresponding to the wide null notch method to obtain the weight coefficient W of the wide null notch beamforming method corresponding to the sea clutter at the azimuth θ _j :

By traversing θ (0°-360°), it plays the role of scanning all angles;

Step 46: By traversing θ _i , obtain the weight coefficient W of the wide null-notch beamforming method corresponding to all sea clutter;

Step five: Use the weight coefficient W of the wide null-notch beamforming method obtained in step four to process the three-dimensional spectrum data CDR obtained in step two, and obtain the angle × Doppler × distance three-dimensional spectrum data after sea clutter is suppressed.

The beneficial effects of the present invention are:

A wide null notch beamforming method based on compensating antenna pattern error described in the present invention provides an effective method for suppressing broadening sea clutter for shipboard high-frequency ground wave radar affected by antenna pattern error Solution. By means of active correction, the data of the antenna pattern error is obtained, so that the original array steering vector is corrected, and the influence of the array affected by the error on the sea clutter information is fully considered, and the error information is used to improve the Based on the original orthogonal weighting method; and according to the problem of low error acquisition accuracy in the actual environment, a wide-null beamforming method was proposed, and it was first applied to shipboard high-frequency ground wave radar in the environment of antenna pattern error clutter suppression. Utilize the wide null notch beamforming method based on compensating the antenna pattern error proposed in the present invention to process the echo data of the shipboard high-frequency ground wave radar, and solve the problem that the traditional clutter suppression algorithm cannot The problem of suppressing broadened first-order sea clutter.

From Figure 9 and Table 3, the average power of sea clutter before suppression is 47.16dB, the target peak power is 61.15dB, and the signal-to-noise ratio is 9.48dB; the average power of sea clutter obtained by the traditional orthogonal weighting method is 41.50dB, and the target The peak power is 60.13dB, and the signal-to-noise ratio is 9.1dB; the sea clutter average power obtained by the wide null notch beamforming method of the present invention is 23.51dB, the target peak power is 55.02dB, and the signal-to-noise ratio is 34.49dB; it can be seen that in In the error environment, the traditional orthogonal weighting method has the same effect as before suppression, but the method of the present invention greatly improves the two indicators of sea clutter average power and signal-to-noise ratio under the condition that the target peak power is less affected. The effectiveness of the inventive method proved in this way. Utilize the wide null notch beamforming method based on compensating the antenna pattern error proposed in the present invention to process the echo data of the shipboard high-frequency ground wave radar, and solve the problem that the traditional orthogonal weighting method cannot correct the widened sea clutter under error conditions. problem of wave suppression.

Description of drawings

Fig. 1 is the general flowchart of invention;

Figure 2 is a schematic diagram of the receiving array of the shipboard high-frequency ground wave radar;

Figure 3a is a diagram of the amplitude error of the measured antenna element 1;

Figure 3b is a diagram of the amplitude error of the measured antenna array element 2;

Figure 3c is a diagram of the amplitude error of the measured antenna array element 3;

Figure 3d is a diagram of the amplitude error of the measured antenna array element 4;

Figure 3e is a diagram of the amplitude error of the measured antenna array element 5;

Figure 3f is a diagram of the amplitude error of the measured antenna array element 6;

Figure 3g is a diagram of the amplitude error of the measured antenna array element 7;

Figure 3h is a diagram of the amplitude error of the measured antenna array element 8;

Figure 4a is a phase error diagram of the measured antenna element 1;

Figure 4b is a phase error diagram of the measured antenna array element 2;

Figure 4c is a phase error diagram of the measured antenna element 3;

Figure 4d is a phase error diagram of the measured antenna element 4;

Figure 4e is a phase error diagram of the measured antenna array element 5;

Figure 4f is a phase error diagram of the measured antenna element 6;

Figure 4g is a phase error diagram of the measured antenna array element 7;

Figure 4h is a phase error diagram of the measured antenna array element 8;

Fig. 5 is a comparison diagram of the antenna pattern corresponding to the corrected weight coefficient and the traditional orthogonal weighting method in the error environment;

Fig. 6 is a comparison diagram of the antenna pattern corresponding to the method of the present invention and the traditional orthogonal weighting method in an error environment;

Figure 7a is a cross-sectional view of the range-Doppler spectrum under the error environment of the traditional orthogonal weighting method;

Fig. 7b is a cross-sectional view of the range Doppler spectrum under the error environment of the method of the present invention;

Fig. 8a is a comparison diagram of the angle Doppler cross-section between the method of the present invention and the traditional orthogonal weighting method in an error environment;

Fig. 8b is a comparison diagram of the angle Doppler cross-section between the method of the present invention and the traditional orthogonal weighting method in an error environment;

FIG. 9 is a Doppler cross-sectional view of the target corresponding to the method of the present invention and the traditional orthogonal weighting method in an error environment.

Detailed ways

Specific embodiment one: illustrate this embodiment in conjunction with Fig. 1, a kind of wide null notch beamforming method based on compensating antenna pattern error of this embodiment specific process is:

Step 1: Obtain the antenna pattern error data of each angle corresponding to the antenna affected by the error through active correction, denoted as r(θ);

Step 2: Perform pulse compression and coherent accumulation processing on the echo data of the shipboard high-frequency ground wave radar to obtain channel × Doppler × range three-dimensional spectrum data, which is recorded as CDR;

Step 3: Based on the error data r(θ) obtained in step 1, correct the original array steering vector (array steering vector without error) to obtain the disturbed projection matrix Based on the disturbed projection matrix Get the normalized modified orthogonal weighting method weight coefficient The specific process is:

Step 31: The first-order Bragg frequency is deduced from the principle of Bragg resonance scattering and the principle of deep water dispersion:

Among them, f _B is the Bragg frequency, Bragg frequency is the Bragg frequency, f ₀ is the radar operating frequency, and its unit is MHz;

Step 32: Through the three-dimensional spectral data CDR obtained in step 2, find the Doppler frequency f _d corresponding to the Doppler unit, and obtain the azimuth θ _i of the sea clutter corresponding to f _d :

Among them, v _p is the moving speed of the shipboard platform, θ _i ∈ [0,2π];

Step 33: The array steering vector a(θ _i ) corresponding to sea clutter in azimuth θ _i is:

Step 3 and 4: Use the antenna pattern error data r(θ _i ) obtained in step ₁ to construct the corrected array steering vector

Wherein, ο represents the Hadamard product; r (θ _i ) is the antenna pattern error data of the azimuth θ _i of the sea clutter corresponding to the antenna affected by the error;

Step 3 and 5: Using the Corrected Array Steering Vectors Construct the disturbed projection matrix

Among them, I _M is the unit matrix whose order is the number of array elements M, and the superscript H represents the conjugate transpose;

Step 36: Utilize the disturbed projection matrix Get the weight coefficient of the normalized modified orthogonal weighting method corresponding to the sea clutter with the azimuth θ _i

Among them, s(θ) is the scanning cycle vector, which plays the role of scanning all angles by traversing θ(0°-360°);

Step 37: By traversing θ _i , obtain the normalized weight coefficients of the modified orthogonal weighting method corresponding to all sea clutter

Step 4: Set the width of the wide null trap to Δθ, reconstruct K null traps within Δθ near the clutter orientation θ _i , and use the corrected steering vector corresponding to the reconstructed null trap Instead of the steering vector corrected in step 3 And according to the method in step 3, the weight coefficient W of the wide null-notch beamforming method is obtained; the specific process is:

Step 41: Find the sea clutter azimuth θ _i corresponding to Step 32, set the width of wide nulls to Δθ, the number of reconstructed nulls after improvement is K, and construct the angle corresponding to the improved nulls:

Among them, θ _k is the angle corresponding to the kth null trap after improvement;

Step 42: Use the K angles obtained in Step 41 to construct the corresponding ideal array steering vector:

Step 43: Construct the corrected array steering vector

Wherein, r(θ _k ) is the antenna pattern error data of the θ _kth angle corresponding to the antenna affected by the error;

Step 44: Utilize the Corrected Array Steering Vectors Construct the projection matrix J corresponding to the wide null notch beamforming method:

in, is the modified array-steering vector matrix,

Step 4 and 5: Use the projection matrix J corresponding to the wide null notch method to obtain the weight coefficient W of the wide null notch beamforming method corresponding to the sea clutter at the azimuth θ _j :

By traversing θ (0°-360°), it plays the role of scanning all angles;

Step 46: By traversing θ _i , obtain the weight coefficient W of the wide null-notch beamforming method corresponding to all sea clutter;

Step five: Use the weight coefficient W of the wide null-notch beamforming method obtained in step four to process the three-dimensional spectrum data CDR obtained in step two, and obtain the angle × Doppler × distance three-dimensional spectrum data after sea clutter is suppressed.

Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that in said step 1, the antenna pattern error data of each angle corresponding to the antenna affected by the error is obtained through active correction, denoted as r(θ) ; The specific process is:

Step 11: The receiving array of the shipboard high-frequency ground wave radar adopts a uniform linear array as shown in Fig. 2, the number of array elements is set as M, the distance between array elements is d, the radar wavelength is λ=c/f ₀ , c is the speed of light, f ₀ is the radar working carrier frequency, and the target is set up at the azimuth where the included angle with the radar array is θ;

Step 1 and 2: The array receives the echo data of the target, and based on the data amplitude obtained by the first array element, the data amplitude obtained by other array elements is respectively compared with the data amplitude of the first array element to obtain the difference Denoted as the amplitude disturbance ρ _m (θ) in the θ direction, m=1,2,...,M,

Among them, m represents the mth array element, and θ represents the angle between the target and the radar array;

Based on the data phase obtained by the first array element, the data phases obtained by other array elements are respectively compared with the data phase obtained by the first array element, and then the original phase difference d between each array element is subtracted /λ·(m-1)·cosθ, recorded as the phase disturbance in the θ direction

Step 13: Process the obtained amplitude disturbance and phase disturbance to obtain the error data of the antenna pattern with the direction θ Superscript T represents transpose, j is imaginary number unit, j ² =-1;

Rotate the target placement angle from 0° to 360°, scan the angle at an interval of 1°, and obtain the error data of the antenna pattern at each angle.

Other steps and parameters are the same as those in Embodiment 1.

Specific embodiment three: the difference between this embodiment and specific embodiment one or two is that in the step two, pulse compression and coherent accumulation are performed on the echo data of the shipboard high-frequency ground wave radar, and the channel × Doppler is obtained. Le × distance three-dimensional spectrum data, recorded as CDR; the specific process is:

Step 21: Perform pulse compression on the echo data of the target received by the array, and perform appropriate N-1 section truncation processing to obtain N range units;

Step 22: Perform FFT processing on all accumulated echoes of each range unit, and then perform coherent accumulation to obtain L Doppler units, and finally obtain channel (number of array elements)×Doppler×range three-dimensional spectrum data , denoted as CDR;

The FFT is a fast Fourier transform.

Other steps and parameters are the same as those in Embodiment 1 or Embodiment 2.

Embodiment 4: The difference between this embodiment and Embodiment 1 to 3 is that in the step 36, the scanning cycle vector s(θ)=[s _1θ (θ),...,s _mθ (θ) ,...,s _Mθ (θ)] ^T , its size is M×1, s _mθ (θ) is the mth element in the scanning cycle vector, s _mθ (θ)＝e ^{j·2π·(m-1 )·d·cosθ/λ} , m=1,2,...,M, superscript T represents transpose.

Other steps and parameters are the same as those in Embodiments 1 to 3.

Specific embodiment five: the difference between this embodiment and one of the specific embodiments one to four is that in the step five, the weight coefficient W of the wide null notch beamforming method obtained in the step four is used to carry out the three-dimensional spectral data CDR obtained in the step two After the sea clutter is suppressed, the angle × Doppler × distance three-dimensional spectrum data is obtained; the specific process is:

Step 51: Select the CDR data obtained in step 2, select a certain distance Doppler unit, find the location of the sea clutter according to the Doppler corresponding unit, and use the weight coefficient W of the wide zero-notch beamforming method obtained in step 4 Process the data of a range Doppler unit to obtain the angle spectrum after filtering out the clutter of a range Doppler unit;

Step 52: Traverse the range-Doppler unit to obtain the angle × Doppler × range three-dimensional spectral data after sea clutter is suppressed.

Other steps and parameters are the same as in one of the specific embodiments 1 to 4.

Adopt the following examples to verify the beneficial effects of the present invention:

Embodiment one:

In this embodiment, a wide null-notch beamforming method based on compensating antenna pattern errors is specifically implemented according to the following steps:

The simulation parameters are shown in the table below:

Table 1 Shipborne HFSWR system parameter settings

Table 2 Simulation target parameter settings

Step 1: Measure the antenna pattern of the array by means of active correction, and obtain the error data r(θ) of the antenna pattern for each angle of the antenna. The obtained measured antenna amplitude error and phase error are shown in Figures 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h and Figures 4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h.

Step 2: Perform pulse compression and coherent accumulation processing on the echo data of the shipboard high-frequency ground wave radar to obtain channel × Doppler × range three-dimensional spectrum data, which is recorded as CDR, and its size is 8 × 512 × 120.

Step 3: Correct the original array steering vector through the obtained error data r(θ) to obtain the disturbed projection matrix Then get the normalized modified orthogonal weighting method weight coefficient The comparison between the corrected weight coefficients and the antenna pattern corresponding to the traditional orthogonal weighting method in the error environment is shown in Figure 5.

Step 4: Near the azimuth formed by clutter, the width of the wide null is Δθ=2°, the number of reconstructed nulls after improvement is K=3, and the reconstructed array steering vector replaces the original one in step 3 The array steering vector is obtained, and the weight coefficient W of the wide null-notch beamforming method is obtained. The comparison of the antenna pattern corresponding to the weight of the wide null-notch beamforming method and the traditional orthogonal weighting method in the error environment is shown in Figure 6.

Step 5: Utilize the weight coefficient of the obtained wide null notch beamforming method to process the CDR data, and obtain the wide null notch beamforming method to the shipboard high frequency ground wave radar echo data processing result, the inventive method and traditional orthogonal Figure 7a and 7b show the comparison of the RD spectrum section of the weighting method, Figures 8a and 8b show the comparison of the AD spectrum section, and Figure 9 shows the comparison of the corresponding target Doppler section.

The simulation results prove that:

Observing Figure 5, it can be seen that assuming the target azimuth is 120°, the azimuth corresponding to the sea clutter on the front of the radar is 60°, and the azimuth corresponding to the sea clutter on the back is 300°. It can be seen from the figure that under the error condition, the traditional orthogonal weighting method distorts the antenna pattern and cannot form a null at the azimuth corresponding to the clutter; while the modified orthogonal weighting method can effectively estimate the azimuth of the target signal at 120° At the same time, null traps are formed at the azimuths of 60° and 300° for the two sea clutters, which can effectively filter the clutter.

Observing Figure 6, it can be seen that assuming the target azimuth is 120°, the azimuth corresponding to the sea clutter on the front of the radar is 60°, and the azimuth corresponding to the sea clutter on the back is 300°. It can be seen from the figure that the wide null notch beamforming method has a wider null than the conventional orthogonal weighting method; when affected by the antenna pattern error, the traditional orthogonal weighting method fails, while the wide null notch beamforming method can still A wide null is formed in the corresponding clutter azimuth, so as to achieve the purpose of suppressing clutter.

Observe Figures 7a, 7b and Figures 8a, 8b. It can be seen from the figure that the traditional orthogonal weighting method cannot suppress the widened sea clutter under the error environment of the antenna pattern, and the target is submerged in the sea clutter; the method proposed in the present invention can suppress the sea clutter under the error condition Suppression is performed, and the target is clearly revealed.

Looking at Figure 9, the inhibition results of the two methods are shown in Table 3 after calculation. It can be seen from Fig. 9 and Table 3 that in the error environment, the traditional orthogonal weighting method has the same effect as that before no suppression, while the method of the present invention greatly improves the sea clutter average Two indexes of power and signal-to-noise ratio prove the effectiveness of the present invention. Utilize the wide null notch beamforming method based on compensating the antenna pattern error proposed in the present invention to process the echo data of the shipboard high-frequency ground wave radar, and solve the problem that the traditional orthogonal weighting method cannot correct the widened sea clutter under error conditions. problem of wave suppression.

Table 3 method inhibition results

The present invention can also have other various embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations are all Should belong to the scope of protection of the appended claims of the present invention.

Claims (5)

1. A wide zero notch beam forming method based on compensation antenna directional diagram errors is characterized in that: the method comprises the following specific processes:

the method comprises the following steps: obtaining antenna directional diagram error data of each angle corresponding to the antenna affected by the error through active correction, and recording the antenna directional diagram error data as r (theta);

step two: performing pulse compression and coherent accumulation processing on echo data of the ship-borne high-frequency ground wave radar to obtain three-dimensional spectrum data of channel multiplied by Doppler multiplied by distance, and recording the three-dimensional spectrum data as CDR;

step three: based on the error data r (theta) obtained in the step one, the original array guide vector is corrected to obtain the interfered projection matrixDisturbed based projection matrixObtaining normalized modified orthogonal weighting method weight coefficientsThe specific process is as follows:

step three, firstly: the first-order Bragg frequency is derived from the Bragg resonance scattering principle and the deep water dispersion principle:

wherein f is_BIs the Bragg frequency, the Bragg frequency is the Bragg frequency, f₀Is the radar operating frequency, which is in MHz;

step three: finding out the Doppler frequency f corresponding to the Doppler unit through the three-dimensional spectral data CDR obtained in the step two_dTo obtain f_dAzimuth theta of corresponding sea clutter_i：

Wherein v is_pIs the moving speed of the ship-based platform, theta_i∈[0,2π]；

Step three: orientation theta_iArray steering vector a (theta) corresponding to sea clutter_i) Comprises the following steps:

step three and four: the azimuth theta obtained by the step one_iAntenna pattern error data r (theta)_i) Constructing a corrected array steering vector

Wherein,represents a Hadamard product; r (theta)_i) Azimuth theta of sea clutter corresponding to the error-affected antenna_iAntenna pattern error data of (a);

step three and five: using modified array steering vectorsConstructing disturbed projection matrices

Wherein, I_MThe unit array with the order of the array element number M is adopted, and the superscript H represents the conjugate transpose;

step three and six: using disturbed projection matricesObtaining an orientation of theta_iNormalized corrected orthogonal weighting method weight coefficient corresponding to sea clutter

Wherein s (theta) is a scanning circulation vector, and all angles are scanned by traversing theta;

step three, pseudo-ginseng: by traversing theta_iObtaining the normalized correction orthogonal weighting method weight coefficient corresponding to all the sea clutter

Step four: setting the width of the wide null as delta theta and theta in clutter azimuth_iReconstructing K nulls in the vicinity of delta theta, and corresponding modified guide vectors to the reconstructed nullsGuide vector replacing correction in step threeObtaining a wide zero-trap beam forming method weight coefficient W according to the method in the third step; the specific process is as follows:

step four, firstly: finding out the corresponding sea clutter azimuth theta in the third step and the second step_iSetting the width of the wide null as delta theta, and constructing the corresponding angle of the improved null, wherein the reconstructed null number is K after improvement:

wherein, theta_kThe angle corresponding to the k-th null is improved;

step four and step two: constructing a corresponding ideal array guide vector by using the K angles obtained in the first step:

step four and step three: constructing a modified array steering vector

Wherein, r (theta)_k) Theta corresponding to the antenna affected by the error_kAngular antenna pattern error data;

step four: using modified array steering vectorsConstructing a projection matrix J corresponding to the wide zero-trap beam forming method:

wherein,the vector matrix is steered to the array after modification,

step four and five: obtaining a projection matrix J corresponding to the wide null method to obtain the azimuth theta_jForming a method weight coefficient W by a wide zero-trap beam corresponding to the sea clutter:

scanning all angles by traversing theta;

step four and six: by traversing theta_iObtaining wide zero-trapped wave beam forming method weight coefficients W corresponding to all sea clutter;

step five: and (4) processing the three-dimensional spectral data CDR obtained in the step (II) by using the wide zero-notch beam forming method weight coefficient W obtained in the step (IV) to obtain angle multiplied by Doppler multiplied by distance three-dimensional spectral data after sea clutter suppression.

2. The method of claim 1, wherein the wide null notch beamforming method is based on compensating antenna pattern errors, and comprises: obtaining antenna directional diagram error data of each angle corresponding to the antenna affected by the error through active correction in the first step, and recording the antenna directional diagram error data as r (theta); the specific process is as follows:

the method comprises the following steps: the receiving array of the ship-borne high-frequency ground wave radar adopts a uniform linear array, the number of array elements is M, the spacing between the array elements is d, and the wavelength of the radar is lambda ═ c/f₀C is the speed of light, f₀Setting a target for a radar working carrier frequency in a direction with an included angle theta with the radar array;

the first step is: the array receives echo data of a target, on the basis of the data amplitude obtained by the first array element, the data amplitudes obtained by other array elements are respectively differed with the data amplitude of the first array element, and the obtained difference is recorded as the amplitude disturbance rho in the theta direction_m(θ),m＝1,2,...,M；

Wherein m represents the mth array element, and theta represents the arrangement included angle between the target and the radar array;

based on the data phase obtained by the first array element, the data phases obtained by other array elements are respectively differenced with the data phase obtained by the first array element, and then the original phase difference d/lambda (m-1) · cos theta among the array elements is subtracted, and the difference is recorded as the phase perturbation in the theta direction

Step one is three: processing the obtained amplitude disturbance and phase disturbance to obtain antenna directional diagram error data with the direction of thetaThe superscript T stands for transpose, j is an imaginary unit, j²＝-1；

And rotating the target placement angle by 0-360 degrees, and scanning the target placement angle at intervals of 1 degree to obtain antenna directional diagram error data of each angle.

3. The method of claim 2, wherein the wide null notch beamforming method is based on compensating antenna pattern errors, and comprises: in the second step, the echo data of the ship-borne high-frequency ground wave radar is subjected to pulse compression and coherent accumulation processing to obtain three-dimensional spectrum data of channel multiplied by Doppler multiplied by distance, and the three-dimensional spectrum data is recorded as CDR; the specific process is as follows:

step two, firstly: performing pulse compression on echo data of a target received by the array, and performing N-1 section truncation processing to obtain N distance units;

step two: performing FFT processing on all accumulated echoes of each distance unit, and performing coherent accumulation to obtain L Doppler units, and finally obtaining three-dimensional spectral data of channel multiplied by Doppler multiplied by distance, which is recorded as CDR;

the FFT is a fast fourier transform.

4. The method of claim 3, wherein the wide null notch beamforming method is based on compensating antenna pattern errors, and comprises: scanning cycle vector s (theta) ═ s in the third step and the sixth step_1θ(θ),...,s_mθ(θ),...,s_Mθ(θ)]^TThe size of which is Mx 1, s_mθ(theta) is the mth element in the scan cycle vector,the superscript T stands for transpose.

5. The method of claim 4, wherein the wide null notch beamforming method comprises: processing the three-dimensional spectral data CDR obtained in the step two by using the weight coefficient W of the wide zero-trap beam forming method obtained in the step four to obtain angle multiplied by Doppler multiplied by distance three-dimensional spectral data after sea clutter is suppressed; the specific process is as follows:

step five, first: selecting the CDR data acquired in the step two, selecting a certain range-Doppler unit, finding the position of the sea clutter according to the Doppler corresponding unit, and processing the data of the certain range-Doppler unit by using the wide zero notch beam forming method weight coefficient W obtained in the step four to obtain an angle spectrum with one range-Doppler unit clutter filtered;

step five two: and traversing the range-Doppler unit to obtain angle multiplied by Doppler multiplied by range three-dimensional spectral data after sea clutter is inhibited.