CN111007466B - DCAR interference suppression method and system based on introduced range gate degree of freedom - Google Patents
DCAR interference suppression method and system based on introduced range gate degree of freedom Download PDFInfo
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- 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
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Abstract
The invention belongs to the technical field of radars, and particularly relates to a DCAR interference suppression method and system based on introduction of a range gate degree of freedom, wherein the method comprises the following steps: four-dimensional echo data, priori target position coordinates, platform coordinates and interference angles are obtained; sequentially carrying out target direction envelope alignment and phase alignment on the four-dimensional echo data to obtain corresponding four-dimensional echo data after target coherent accumulation; performing sample reconstruction on four-dimensional echo data subjected to target coherent accumulation by using a method of introducing the degree of freedom of a range gate to obtain new sample data and data to be processed; obtaining an adaptive weight vector w under a new sample according to the corresponding new sample data, and carrying out adaptive beamforming on the data to be processed according to the adaptive weight vector w to obtain adaptive beamformed data; and carrying out Doppler domain filtering on the data after the self-adaptive beam forming to obtain the data after interference suppression. The invention improves the interference suppression performance and the detection performance of the distributed phase-coherent radar, and is favorable for realizing the distributed phase-coherent synthesis.
Description
Technical Field
The invention belongs to the technical field of radars, and particularly relates to a DCAR interference suppression method and system based on the degree of freedom of an introduced range gate.
Background
The distributed coherent radar system adopts multi-station combined processing to carry out interference suppression, and as the interval of each platform and the configuration of the distributed coherent radar are different, when the interference reaches each receiving platform, the distance gate where the interference is located is different, and the delay in quick time caused by the distance is not negligible, and the initial phase of the interference envelope is different. In the case of misaligned interference envelopes, the multi-station joint processing by using only spatial degrees of freedom directly affects the interference suppression performance in the case of multi-station joint processing, and the main problem sources are as follows: the interference has resolving power not only in the airspace but also in the distance domain, and at the moment, the interference suppression only can be performed by using the airspace degree of freedom, so that the interference can be suppressed at the position close to the axial included angle of the array, the suppression performance can be poor for the interference with the axial included angle of the array, particularly, when the included angle is close to 0 degree, the interference can be hardly suppressed, and the interference suppression performance is seriously affected.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a DCAR interference suppression method and system based on the degree of freedom of an introduced range gate. The technical problems to be solved by the invention are realized by the following technical scheme:
a DCAR interference suppression method based on introducing a range gate degree of freedom comprises the following steps:
four-dimensional echo data, priori target position coordinates, platform coordinates and interference angles are obtained;
sequentially carrying out target direction envelope alignment and phase alignment on the four-dimensional echo data to obtain corresponding four-dimensional echo data after target phase-coherent accumulation;
performing sample reconstruction on the four-dimensional echo data subjected to target coherent accumulation by using a method of introducing the degree of freedom of a range gate to obtain new sample data and data to be processed;
obtaining an adaptive weight vector w under a new sample according to the corresponding new sample data, and carrying out adaptive beam forming on the data to be processed according to the adaptive weight vector w to obtain data after adaptive beam forming;
and carrying out Doppler domain filtering on the data after the self-adaptive wave beam forming to obtain data after interference suppression.
In one embodiment of the present invention, performing object direction envelope alignment and phase alignment on the four-dimensional echo data in sequence to obtain corresponding four-dimensional echo data after object coherent accumulation, including:
1) Calculating the distance R from the target to each platform according to the prior target position coordinates and the platform coordinates i Distance R from target to reference platform 1 Distance difference Δr of (2) i The method comprises the steps of carrying out a first treatment on the surface of the According to the distance difference DeltaR i Obtaining the phase difference
Wherein pi is the circumference ratio, lambda is the wavelength, theta 0 For the azimuth angle of the target +.>
The pitch angle of the target; compensating the phase difference caused by the time delay difference caused by different distances between targets and each platform for the subarray inter-platform dimension of the four-dimensional echo data to obtain four-dimensional echo data with target envelope aligned, wherein the dimension of the four-dimensional echo data is NR a xMR xK x L, where NR a As the number of array elements in subarrays, NR a More than or equal to 1, MR is the number of platforms, MR is more than or equal to 2,K is the number of pulses, and L is the number of distance gates;
2) Calculating the interval D from each platform to the reference platform according to the coordinates of each platform i Obtaining the phase difference between each platform and the reference platform under far field condition
Obtaining the phase difference from each array element in the platform to the first array element according to the half-wavelength interval d between each array element in the platform to be +.>
Utilizing the inter-platform phase difference and the intra-platform phase difference to perform kronecker product to obtain the phase difference of each array element relative to a reference array element; and compensating the phase difference caused by the platform interval and the array element interval for the array element in the subarray and the platform dimension between subarrays of the four-dimensional echo data after the target envelope alignment to obtain the four-dimensional echo data after the target coherent accumulation.
In one embodiment of the present invention, a method for introducing a degree of freedom of a range gate is used to reconstruct samples of four-dimensional echo data of the target after coherent accumulation to obtain new sample data and data to be processed, including:
1) Traversing pulse dimensions of the four-dimensional echo data after the target phase-coherent accumulation, and removing targets in the four-dimensional echo data after the target phase-coherent accumulation by using a generalized inner product method; the degree of freedom of the range gate is 5D, when the target is removed, the range gate to be removed is required to be marked, two range gates on the left and the right of the range gate to be removed are marked, and note that the two range gates at the beginning and the two range gates at the end are marked as well, the marked range gate cannot be used as the center of a sample of the degree of freedom of the range gate, and the number of the marked range gates is l;
2) Pulse dimension traversal of four-dimensional echo data after coherent accumulation of the target, selecting three-dimensional echo data corresponding to the pulse, traversing all the distance gates which are not marked in the three-dimensional echo data, reconstructing the distance gate to be detected and the data of the left and right distance gates into a row of data, namely the original NR (non-return) data a The xMR x 5-dimensional matrix transform is (NR a The column vector of xMR x 5) x 1 is used as the data to be measured of the current distance gate, namely the dimension of the new sample data for solving the covariance matrix R is changed from the original NR a The xMR xK x L' dimension becomes (NR a X MR x 5) x K x L 'dimensions, where L' =l-L is the number of remaining range gates from which the marked range gates are removed; similarly, pulse dimension traversal of the four-dimensional echo data after target coherent accumulation is performed, three-dimensional echo data corresponding to pulses is selected, all range gate traversals of the three-dimensional echo data are performed, the same operation of introducing the degree of freedom of the range gate is performed, reconstructed data to be processed is obtained, and the dimension is represented by the original NR (non-return ratio) a The xMR xK xL dimension becomes (NR a ×MR×5)×K×L。
In one embodiment of the present invention, the adaptive weight vector w under a new sample is obtained according to the corresponding new sample data, and the adaptive beamforming is performed on the data to be processed according to the adaptive weight vector w to obtain adaptive beamformed data, which includes:
1) Using the formula
Obtaining a covariance matrix R under a new sample, wherein x is the new sample data and the dimension is (NR a ×MR×5)×(K×L')；
2) Using the formula
When the adaptive weight vector w is calculated, the dimension of the spatial domain guide vector s is changed from the original (NR a XMR). Times.1-dimensional becomes (NR) a X MR x 5) x 1 dimension; the airspace guiding vector before the degree of freedom of the distance gate is introduced is
Wherein->
The direction vector of the distance domain after the degree of freedom of the distance gate is introduced is S l ＝[0,0,1,0,0]' from the airspace guide vector S before the introduction of the degree of freedom of the distance gate 0 And a distance domain steering vector S l Obtaining a guiding vector introducing the degree of freedom of the range gate +.>
Wherein->
Is kronecker product;
3) Using the formula y=w H Performing adaptive beam forming on the data to be processed by X to obtain data after adaptive beam forming, wherein X is the data to be processed and the dimension is (NR a ×MR×5)×(K×L)。
In one embodiment of the present invention, performing doppler domain filtering on the adaptive beamformed data to obtain interference-suppressed data includes:
and performing Chebyshev window processing on the self-adaptive beam formed data in a pulse domain to obtain windowed data, and performing FFT (fast Fourier transform) on the windowed data in the pulse domain to obtain space-time processed data, namely the data after interference suppression is completed.
The invention also provides a DCAR interference suppression system based on the degree of freedom of the introduced range gate, which comprises the following components:
the data acquisition module is used for acquiring four-dimensional echo data, priori target position coordinates, platform coordinates and interference angles;
the target direction phase-coherent accumulation module is used for sequentially carrying out target direction envelope alignment and phase alignment on the four-dimensional echo data to obtain corresponding four-dimensional echo data after target phase-coherent accumulation;
the sample data reconstruction module is used for carrying out sample reconstruction on the four-dimensional echo data which are subjected to coherent accumulation of the target by utilizing a method for introducing the degree of freedom of the distance gate to obtain new sample data and data to be processed;
and the multi-station joint processing module is used for obtaining an adaptive weight vector w under a new sample according to the corresponding new sample data, carrying out adaptive beam forming on the data to be processed, and carrying out Doppler domain filtering on the data after the adaptive beam forming according to the adaptive weight vector w to obtain data after interference suppression to obtain the data after the adaptive beam forming.
In one embodiment of the present invention, the target direction coherent accumulation module includes:
the target direction envelope alignment unit obtains distance differences according to the prior target position coordinates and the platform coordinates, and calculates phase differences caused by time delay differences caused by different distances of the target reaching the platforms according to the distance differences;
and the target direction phase alignment unit obtains the phase difference of each array element relative to the reference array element according to the coordinates of each platform and the intervals of each array element in the subarray.
In one embodiment of the present invention, the sample data reconstruction module for introducing a range gate degree of freedom includes:
obtaining a new sample data unit required by the covariance matrix R, and obtaining new sample data after introducing the degree of freedom of the distance gate according to the four-dimensional data accumulated by the target direction and the marked distance gate;
and calculating a data unit to be processed required by the self-adaptive weight vector w, and obtaining new sample data after introducing the degree of freedom of the distance gate according to the four-dimensional data accumulated by the target direction.
The invention has the beneficial effects that:
1. the multi-station combined processing method for introducing the range gate degree of freedom of the dynamic platform distributed coherent radar system is utilized, the problem that the interference suppression performance is poor in traditional single-station processing, and the multi-interference suppression cannot be suppressed due to the fact that the single-station airspace degree of freedom is small is solved, the interference suppression performance and the detection performance of the distributed coherent radar are improved, and the method can be well applied under the multi-interference condition;
2. the invention utilizes the multi-station combined processing method introducing the degree of freedom of the range gate, solves the problem that partial interference caused by misaligned interference envelopes in the coherent radar systems with different profiles in the prior art cannot be inhibited or the inhibition effect is poor, and can be well applied to the coherent radar systems with different profiles.
The present invention will be described in further detail with reference to the accompanying drawings and examples.
Drawings
Fig. 1 is a schematic flow chart of a DCAR interference suppression method based on introducing a degree of freedom of a range gate according to an embodiment of the present invention;
fig. 2 is a PD processing diagram obtained by a single-station processing method under the condition of only containing noise and targets, according to the DCAR interference suppression method based on the degree of freedom of the introduced range gate provided by the embodiment of the present invention;
fig. 3 is a range-doppler plot obtained by a single-station processing method under the condition that the interference number is 40, based on a DCAR interference suppression method introducing a range gate degree of freedom provided by the embodiment of the present invention;
fig. 4 is a PD processing diagram obtained by a multi-station joint processing method for introducing a degree of freedom of a range gate under the condition of only containing noise and a target according to the DCAR interference suppression method based on introducing the degree of freedom of the range gate provided by the embodiment of the present invention;
fig. 5 is a range-doppler plot obtained by a multi-station joint processing method for introducing a degree of freedom of a range gate under the condition that the interference number is 40, according to the DCAR interference suppression method based on introducing the degree of freedom of the range gate provided by the embodiment of the present invention;
fig. 6 is a block diagram of a DCAR interference suppression system based on introducing a degree of freedom of a range gate according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to specific examples, but embodiments of the present invention are not limited thereto.
Referring to fig. 1, fig. 1 is a schematic flow chart of a DCAR interference suppression method based on introducing a degree of freedom of a range gate according to an embodiment of the present invention, including:
four-dimensional echo data, priori target position coordinates, platform coordinates and interference angles are obtained;
sequentially carrying out target direction envelope alignment and phase alignment on the four-dimensional echo data to obtain corresponding four-dimensional echo data after target phase-coherent accumulation;
performing sample reconstruction on the four-dimensional echo data subjected to target coherent accumulation by using a method of introducing the degree of freedom of a range gate to obtain new sample data and data to be processed;
obtaining an adaptive weight vector w under a new sample according to the corresponding new sample data, and carrying out adaptive beam forming on the data to be processed according to the adaptive weight vector w to obtain data after adaptive beam forming;
and carrying out Doppler domain filtering on the data after the self-adaptive wave beam forming to obtain data after interference suppression.
The invention utilizes the multi-station joint processing method of the dynamic platform distributed coherent radar system for introducing the range gate degree of freedom, overcomes the problems that the traditional single-station processing interference suppression performance is poor and the multi-interference suppression cannot be suppressed due to the small single-station airspace degree of freedom, improves the interference suppression performance and the detection performance of the distributed coherent radar (DCAR, distributed Coherent Aperture Radar), and ensures that the invention has good applicability under the multi-interference condition.
In one embodiment of the present invention, performing object direction envelope alignment and phase alignment on the four-dimensional echo data in sequence to obtain corresponding four-dimensional echo data after object coherent accumulation, including:
1) Calculating the distance R from the target to each platform according to the prior target position coordinates and the platform coordinates i Distance R from target to reference platform 1 Distance difference Δr of (2) i The method comprises the steps of carrying out a first treatment on the surface of the According to the distance difference DeltaR i Obtaining the phase difference
Wherein pi is the circumference ratio, lambda is the wavelength, theta 0 For the azimuth angle of the target +.>
The pitch angle of the target; compensating the phase difference caused by the time delay difference caused by different distances between targets and each platform for the subarray inter-platform dimension of the four-dimensional echo data to obtain four-dimensional echo data with target envelope aligned, wherein the dimension of the four-dimensional echo data is NR a xMR xK x L, where NR a As the number of array elements in subarrays, NR a More than or equal to 1, MR is the number of platforms, MR is more than or equal to 2,K is the number of pulses, and L is the number of distance gates;
wherein the pulse number K is an integer multiple of the plateau number.
2) Calculating the interval D from each platform to the reference platform according to the coordinates of each platform i Obtaining the phase difference between each platform and the reference platform under far field condition
Obtaining the phase difference from each array element in the platform to the first array element according to the half-wavelength interval d between each array element in the platform to be +.>
Utilizing the inter-platform phase difference and the intra-platform phase difference to perform kronecker product to obtain the phase difference of each array element relative to a reference array element; and compensating the phase difference caused by the platform interval and the array element interval for the array element in the subarray and the platform dimension between subarrays of the four-dimensional echo data after the target envelope alignment to obtain the four-dimensional echo data after the target coherent accumulation.
The invention utilizes the multi-station combined processing method introducing the degree of freedom of the range gate, solves the problem that partial interference caused by misaligned interference envelopes in the coherent radar systems with different profiles in the prior art cannot be inhibited or the inhibition effect is poor, and can be well applied to the coherent radar systems with different profiles.
In one embodiment of the present invention, a method for introducing a degree of freedom of a range gate is used to reconstruct samples of four-dimensional echo data of the target after coherent accumulation to obtain new sample data and data to be processed, including:
1) Traversing pulse dimensions of the four-dimensional echo data after the target phase-coherent accumulation, and removing targets in the four-dimensional echo data after the target phase-coherent accumulation by using a generalized inner product method; the degree of freedom of the range gate is 5D, when the target is removed, the range gate to be removed is required to be marked, two range gates on the left and the right of the range gate to be removed are marked, and note that the two range gates at the beginning and the two range gates at the end are marked as well, the marked range gate cannot be used as the center of a sample of the degree of freedom of the range gate, and the number of the marked range gates is l;
2) Pulse dimension traversal of four-dimensional echo data after coherent accumulation of the target, selecting three-dimensional echo data corresponding to the pulse, traversing all the distance gates which are not marked in the three-dimensional echo data, reconstructing the distance gate to be detected and the data of the left and right distance gates into a row of data, namely the original NR (non-return) data a The xMR x 5-dimensional matrix transform is (NR a The column vector of xMR x 5) x 1 is used as the data to be measured of the current distance gate, namely the dimension of the new sample data for solving the covariance matrix R is changed from the original NR a The xMR xK x L' dimension becomes (NR a X MR x 5) x K x L 'dimensions, where L' =l-L is the number of remaining range gates from which the marked range gates are removed; similarly, pulse dimension traversal of the four-dimensional echo data after target coherent accumulation is performed, three-dimensional echo data corresponding to pulses is selected, all range gate traversals of the three-dimensional echo data are performed, the same operation of introducing the degree of freedom of the range gate is performed, reconstructed data to be processed is obtained, and the dimension is represented by the original NR (non-return ratio) a The xMR xK xL dimension becomes (NR a ×MR×5)×K×L。
In one embodiment of the present invention, the adaptive weight vector w under a new sample is obtained according to the corresponding new sample data, and the adaptive beamforming is performed on the data to be processed according to the adaptive weight vector w to obtain adaptive beamformed data, which includes:
1) Using the formula
Obtaining a covariance matrix R under a new sample, wherein x is the new sample data and the dimension is (NR a ×MR×5)×(K×L')；
2) Using the formula
When the adaptive weight vector w is calculated, the dimension of the spatial domain guide vector s is changed from the original (NR a XMR). Times.1-dimensional becomes (NR) a X MR x 5) x 1 dimension; the airspace guiding vector before the degree of freedom of the distance gate is introduced is
Wherein->
The direction vector of the distance domain after the degree of freedom of the distance gate is introduced is S l ＝[0,0,1,0,0]' from the airspace guide vector S before the introduction of the degree of freedom of the distance gate 0 And a distance domain steering vector S l Obtaining a guiding vector introducing the degree of freedom of the range gate +.>
Wherein->
Is kronecker product;
3) Using the formula y=w H Performing adaptive beam forming on the data to be processed by X to obtain data after adaptive beam forming, wherein X is the data to be processed and the dimension is (NR a ×MR×5)×(K×L)。
In one embodiment of the present invention, performing doppler domain filtering on the adaptive beamformed data to obtain interference-suppressed data includes:
and performing Chebyshev window processing on the self-adaptive beam formed data in a pulse domain to obtain windowed data, and performing FFT (fast Fourier transform) on the windowed data in the pulse domain to obtain space-time processed data, namely the data after interference suppression is completed.
The effects of the present invention are further described below in conjunction with simulation experiments:
1. simulation conditions:
the simulation experiment environment of the invention is: MATLAB 2018b, intel (R) Xeon (R) CPU 2.20GHz, window 7 specialty.
2. Simulation content and result analysis:
the simulation experiment of the invention utilizes the method of the invention, and utilizes the distributed coherent radar system to receive the echo of the ground moving target with known position coordinates, thereby inhibiting the interference in the distributed coherent radar. The total number of unit radars in the distributed coherent radar system is 4, the unit radars are arranged in a vertical plane configuration, each unit radar has receiving-transmitting co-arrangement property, the total number of distance gates is 834, the total number of transmitted pulse processing periods is 160, the number of receiving array elements in each receiving unit radar is 24, the bandwidth of a transmitted signal is 2MHz, and the pulse repetition frequency is 2.4KHz.
Referring to fig. 2, fig. 2 is a PD processing diagram obtained by a single-station processing method under the condition of only noise and targets by using a DCAR interference suppression method based on introducing a degree of freedom of a range gate according to an embodiment of the present invention; the abscissa in fig. 2 represents the doppler channel, and the ordinate represents the range gate. The block in fig. 2 is a noise power sampling block for estimating the overall noise level and comparing with the average power value of the interference after the interference suppression using the single-station processing method in fig. 3, wherein the average power value of the noise is 2.2052dB, the target power value shown in fig. 2 is 33.9336dB, and the target output of the PD processing and the single-station processing should be substantially unchanged when comparing with the power value of the target obtained after the interference suppression using the single-station processing method in fig. 3.
Referring to fig. 3, fig. 3 is a range-doppler plot obtained by a single-station processing method under the condition that the interference number is 40, based on a DCAR interference suppression method introducing a degree of freedom of a range gate according to an embodiment of the present invention; the abscissa in fig. 3 represents the doppler channel, and the ordinate represents the range gate. The block in fig. 3 is an interference power sampling block for estimating the overall power average of interference after interference suppression by a single station processing method and comparing the noise level in fig. 2, and the average of the interference power in fig. 3 is 3.5523dB; the target power value in fig. 3 is 33.8698dB, and as compared with the target power value in fig. 2, the target output is substantially unchanged.
As can be seen from fig. 3, when the single-station processing method is adopted to perform interference suppression, and the number of interference is large and exceeds half of the spatial degree of freedom, the interference suppression performance is reduced, and comparing the average power value of the interference after the single-station processing method is adopted to perform interference suppression in fig. 3 with the average power value of the noise in fig. 2, it can be seen that the interference is not completely suppressed, and the interference power level after suppression is 1.3471dB higher than the noise.
Referring to fig. 4, fig. 4 is a PD processing diagram obtained by a multi-station joint processing method for introducing a degree of freedom of a range gate under the condition of only containing noise and a target according to the DCAR interference suppression method based on introducing the degree of freedom of the range gate provided by the embodiment of the present invention; the abscissa in fig. 4 represents the doppler channel, and the ordinate represents the range gate. The block in fig. 4 is a noise power sampling block, which is used to estimate the overall noise level and compare with the average power value of interference after interference suppression using the multi-station joint processing method with the degree of freedom of the range gate in fig. 5, the average power value of noise in fig. 4 is-3.7034 dB, the target power value shown in fig. 4 is 33.8612dB, and is used to compare with the power value of the target obtained after interference suppression using the multi-station joint processing method with the degree of freedom of the range gate in fig. 5, where the target outputs of the PD processing and the multi-station joint processing method with the degree of freedom of the range gate should be substantially unchanged.
Referring to fig. 5, fig. 5 is a range-doppler plot obtained by a multi-station joint processing method for introducing a degree of freedom of a range gate under the condition that the interference number is 40 according to the DCAR interference suppression method based on introducing the degree of freedom of the range gate provided by the embodiment of the present invention; the abscissa in fig. 5 represents the doppler channel, and the ordinate represents the range gate. The block in fig. 5 is an interference power sampling block for estimating the overall power average of interference after interference suppression by using the multi-station joint processing method introducing the degree of freedom of the range gate and comparing with the noise level in fig. 4, the average of interference power in fig. 5 is-3.6501 dB; the target power value in fig. 5 is 33.8424dB, and as compared with the target power value in fig. 4, the target output is substantially unchanged.
As can be seen from fig. 5, when the number of interference is large, the interference can be well suppressed by adopting the distributed coherent radar multi-station joint processing interference suppression method introducing the degree of freedom of the range gate, and comparing the average power value of the interference after the interference suppression performed by adopting the distributed coherent radar multi-station joint processing method introducing the degree of freedom of the range gate in fig. 5 with the average power value of the noise in fig. 4, the interference is completely suppressed, and the interference power level after the suppression is basically consistent with the noise level, so that the method can be obtained, and has good applicability under the conditions of multi-interference and different-configuration distributed coherent radar systems.
Referring to fig. 6, fig. 6 is a block diagram of a DCAR interference suppression system based on introducing a degree of freedom of a range gate according to an embodiment of the present invention, including:
the data acquisition module is used for acquiring four-dimensional echo data, priori target position coordinates, platform coordinates and interference angles;
the target direction phase-coherent accumulation module is used for sequentially carrying out target direction envelope alignment and phase alignment on the four-dimensional echo data to obtain corresponding four-dimensional echo data after target phase-coherent accumulation;
the sample data reconstruction module is used for carrying out sample reconstruction on the four-dimensional echo data which are subjected to coherent accumulation of the target by utilizing a method for introducing the degree of freedom of the distance gate to obtain new sample data and data to be processed;
and the multi-station joint processing module is used for obtaining an adaptive weight vector w under a new sample according to the corresponding new sample data, carrying out adaptive beam forming on the data to be processed, carrying out Doppler domain filtering on the data after the adaptive beam forming according to the adaptive weight vector w to obtain data after interference suppression, and obtaining the data after the adaptive beam forming.
In one embodiment of the present invention, the target direction coherent accumulation module includes:
the target direction envelope alignment unit is used for obtaining distance differences according to the prior target position coordinates and the platform coordinates, and calculating phase differences caused by time delay differences caused by different distances of the target reaching the platforms according to the distance differences;
and the target direction phase alignment unit is used for obtaining the phase difference of each array element relative to the reference array element according to the coordinates of each platform and the intervals of each array element in the subarray.
In one embodiment of the present invention, the sample data reconstruction module for introducing a range gate degree of freedom includes:
a new sample data unit required by the covariance matrix R is solved, and the new sample data after the degree of freedom of the distance gate is introduced is obtained according to the four-dimensional data which are accumulated by the target direction and the marked distance gate;
and calculating a data unit to be processed required by the self-adaptive weight vector w, wherein the data unit to be processed is used for obtaining new sample data after introducing the degree of freedom of the range gate according to the four-dimensional data subjected to the coherent accumulation of the target direction.
The foregoing is a further detailed description of the invention in connection with the preferred embodiments, and it is not intended that the invention be limited to the specific embodiments described. It will be apparent to those skilled in the art that several simple deductions or substitutions may be made without departing from the spirit of the invention, and these should be considered to be within the scope of the invention.
Claims (6)
1. A DCAR interference suppression method based on introducing a range gate degree of freedom, comprising:
four-dimensional echo data, priori target position coordinates, platform coordinates and interference angles are obtained;
sequentially carrying out target direction envelope alignment and phase alignment on the four-dimensional echo data to obtain corresponding four-dimensional echo data after target phase-coherent accumulation;
performing sample reconstruction on the four-dimensional echo data subjected to target coherent accumulation by using a method of introducing the degree of freedom of a range gate to obtain new sample data and data to be processed;
obtaining an adaptive weight vector w under a new sample according to the corresponding new sample data, and carrying out adaptive beam forming on the data to be processed according to the adaptive weight vector w to obtain data after adaptive beam forming;
performing Doppler domain filtering on the data after the self-adaptive beam forming to obtain data after interference suppression;
the method for reconstructing samples of four-dimensional echo data accumulated by the target phase by using the method for introducing the degree of freedom of the range gate to obtain new sample data and data to be processed comprises the following steps:
1) Traversing pulse dimensions of the four-dimensional echo data after the target phase-coherent accumulation, and removing targets in the four-dimensional echo data after the target phase-coherent accumulation by using a generalized inner product method; the degree of freedom of the range gate is 5D, when the target is removed, the range gate to be removed is required to be marked, two range gates on the left and the right of the range gate to be removed are marked, and note that the two range gates at the beginning and the two range gates at the end are marked as well, the marked range gate cannot be used as the center of a sample of the degree of freedom of the range gate, and the number of the marked range gates is l;
2) Pulse dimension traversal of four-dimensional echo data after coherent accumulation of the target, selecting three-dimensional echo data corresponding to the pulse, traversing all the distance gates which are not marked in the three-dimensional echo data, reconstructing the distance gate to be detected and the data of the left and right distance gates into a row of data, namely the original NR (non-return) data a The xMR x 5-dimensional matrix transform is (NR a Column vector of xMR x 5) x 1 is used as the data to be measured of the current distance gate, i.e. the new sample data dimension of covariance matrix R is calculated from the original NR a The xMR xK x L' dimension becomes (NR a X MR x 5) x K x L 'dimensions, where L' =l-L is the number of remaining range gates from which the marked range gates are removed; similarly, pulse dimension traversal of the four-dimensional echo data after coherent accumulation of the target is performed, three-dimensional echo data corresponding to the pulse is selected, all range gate traversals of the three-dimensional echo data are performed, the same operation of introducing the degree of freedom of the range gate is performed, and the reconstructed to-be-obtained is obtainedProcessing data, dimension from original NR a The xMR xK xL dimension becomes (NR a ×MR×5)×K×L。
2. The DCAR interference suppression method based on the introduced range gate degree of freedom according to claim 1, wherein sequentially performing target direction envelope alignment and phase alignment on the four-dimensional echo data to obtain corresponding target-coherent-accumulated four-dimensional echo data includes:
1) Calculating the distance R from the target to each platform according to the prior target position coordinates and the platform coordinates i Distance R from target to reference platform 1 Distance difference Δr of (2) i The method comprises the steps of carrying out a first treatment on the surface of the According to the distance difference DeltaR i Obtaining the phase difference
Wherein pi is the circumference ratio, lambda is the wavelength, theta 0 For the azimuth angle of the target +.>
The pitch angle of the target; compensating the phase difference caused by the time delay difference caused by different distances between targets and each platform for the subarray inter-platform dimension of the four-dimensional echo data to obtain the four-dimensional echo data with the target envelope aligned, wherein the four-dimensional echo data has the dimensions of NRa×MR×K×L, NRa is the number of array elements in the subarray, and NR a More than or equal to 1, MR is the number of platforms, MR is more than or equal to 2,K is the number of pulses, and L is the number of distance gates;
2) Calculating the interval Di from each platform to the reference platform according to the coordinates of each platform to obtain the phase difference between each platform and the reference platform under far field conditions
Obtaining the phase difference from each array element in the platform to the first array element according to the half-wavelength interval d between each array element in the platform to be +.>
By using the phase difference between the platformsAnd the phase difference in the platform is processed by kronecker product to obtain the phase difference of each array element relative to the reference array element; and compensating the phase difference caused by the platform interval and the array element interval for the array element in the subarray and the platform dimension between subarrays of the four-dimensional echo data after the target envelope alignment to obtain the four-dimensional echo data after the target coherent accumulation.
3. The DCAR interference suppression method based on introducing a degree of freedom of a range gate according to claim 1, wherein obtaining an adaptive weight vector w under a new sample according to the corresponding new sample data, and performing adaptive beamforming on the data to be processed according to the adaptive weight vector w to obtain adaptive beamformed data, includes:
1) Using the formula
Obtaining a covariance matrix R under a new sample, wherein x is the new sample data and the dimension is (NR a ×MR×5)×(K×L')；
2) Using the formula
When the adaptive weight vector w is calculated, the dimension of the spatial domain guide vector s is changed from the original (NR a XMR). Times.1-dimensional becomes (NR) a X MR x 5) x 1 dimension; the airspace guiding vector before the degree of freedom of the distance gate is introduced is
Wherein->
The direction vector of the distance domain after the degree of freedom of the distance gate is introduced is S l ＝[0,0,1,0,0]' from the airspace guide vector S before the introduction of the degree of freedom of the distance gate 0 And a distance domain steering vector S l Obtaining a guiding vector introducing the degree of freedom of the range gate +.>
Wherein->
Is kronecker product;
3) Using the formula y=w H Performing adaptive beam forming on the data to be processed by X to obtain data after adaptive beam forming, wherein X is the data to be processed and the dimension is (NR a ×MR×5)×(K×L)。
4. The method for DCAR interference suppression based on introducing a range gate degree of freedom according to claim 1, wherein performing doppler domain filtering on the adaptive beamformed data to obtain interference suppressed data comprises:
and performing Chebyshev window processing on the self-adaptive beam formed data in a pulse domain to obtain windowed data, and performing FFT (fast Fourier transform) on the windowed data in the pulse domain to obtain space-time processed data, namely the data after interference suppression is completed.
5. A DCAR interference suppression system based on introducing a range gate degree of freedom, comprising:
the data acquisition module is used for acquiring four-dimensional echo data, priori target position coordinates, platform coordinates and interference angles;
the target direction phase-coherent accumulation module is used for sequentially carrying out target direction envelope alignment and phase alignment on the four-dimensional echo data to obtain corresponding four-dimensional echo data after target phase-coherent accumulation;
the sample data reconstruction module is used for carrying out sample reconstruction on the four-dimensional echo data which are subjected to coherent accumulation of the target by utilizing a method for introducing the degree of freedom of the distance gate to obtain new sample data and data to be processed;
the multi-station joint processing module is used for obtaining an adaptive weight vector w under a new sample according to the corresponding new sample data, carrying out adaptive beam forming on the data to be processed, carrying out Doppler domain filtering on the data after the adaptive beam forming according to the adaptive weight vector w to obtain data after interference suppression, and obtaining the data after the adaptive beam forming;
the method for reconstructing samples of four-dimensional echo data accumulated by the target phase by using the method for introducing the degree of freedom of the range gate to obtain new sample data and data to be processed comprises the following steps:
1) Traversing pulse dimensions of the four-dimensional echo data after the target phase-coherent accumulation, and removing targets in the four-dimensional echo data after the target phase-coherent accumulation by using a generalized inner product method; the degree of freedom of the range gate is 5D, when the target is removed, the range gate to be removed is required to be marked, two range gates on the left and the right of the range gate to be removed are marked, and note that the two range gates at the beginning and the two range gates at the end are marked as well, the marked range gate cannot be used as the center of a sample of the degree of freedom of the range gate, and the number of the marked range gates is l;
2) Pulse dimension traversal of four-dimensional echo data after coherent accumulation of the target, selecting three-dimensional echo data corresponding to the pulse, traversing all the distance gates which are not marked in the three-dimensional echo data, reconstructing the distance gate to be detected and the data of the left and right distance gates into a row of data, namely the original NR (non-return) data a The xMR x 5-dimensional matrix transform is (NR a Column vector of xMR x 5) x 1 is used as the data to be measured of the current distance gate, i.e. the new sample data dimension of covariance matrix R is calculated from the original NR a The xMR xK x L' dimension becomes (NR a X MR x 5) x K x L 'dimensions, where L' =l-L is the number of remaining range gates from which the marked range gates are removed; similarly, pulse dimension traversal of the four-dimensional echo data after target coherent accumulation is performed, three-dimensional echo data corresponding to pulses is selected, all range gate traversals of the three-dimensional echo data are performed, the same operation of introducing the degree of freedom of the range gate is performed, reconstructed data to be processed is obtained, and the dimension is represented by the original NR (non-return ratio) a The xMR xK xL dimension becomes (NR a ×MR×5)×K×L。
6. The DCAR interference suppression system based on introducing a range gate degree of freedom of claim 5, wherein the target direction coherent accumulation module comprises:
the target direction envelope alignment unit is used for obtaining distance differences according to the prior target position coordinates and the platform coordinates, and calculating phase differences caused by time delay differences caused by different distances of the target reaching the platforms according to the distance differences;
and the target direction phase alignment unit is used for obtaining the phase difference of each array element relative to the reference array element according to the coordinates of each platform and the intervals of each array element in the subarray.
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