Non-stationary clutter suppression method and apparatus based on spatiotemporal polarization adaptive processing

Abstract

This invention relates to the field of signal processing technology, and provides a method and apparatus for suppressing non-stationary clutter based on spatiotemporal polarization adaptive processing. The method includes: constructing four-dimensional airborne radar echo data in polarization-elevation-azimuth-Doppler domains; performing Doppler domain dimensionality reduction processing on the four-dimensional airborne radar echo data to obtain processed echo data; calculating a covariance matrix based on the processed echo data; calculating a spatiotemporal polarization adaptive processing weight vector using the covariance matrix; and applying the spatiotemporal polarization adaptive processing weight vector to the echo data of each Doppler channel to obtain processed output data. This invention can suppress short-range clutter entering from the elevation main lobe to a lower level, thereby more effectively suppressing non-stationary clutter and improving the detection probability of target signals.

Description

Technical Field

[0001] This invention relates to the field of signal processing technology, and in particular to a method and apparatus for suppressing non-stationary clutter based on spatiotemporal polarization adaptive processing. Background Technology

[0002] When airborne radar arrays are not positioned with a frontal or side-view orientation, or when conformal or end-fire array antennas are used, the Doppler frequency of airborne radar clutter signals changes with distance, indicating a non-stationary phenomenon in clutter. This non-stationarity manifests specifically in the different space-time trajectories of clutter at different range cells, and the variation of the normalized Doppler frequency of clutter with distance. This non-stationarity is particularly severe at short range. Traditional space-time adaptive processing (STAP) technology performs adaptive processing in the azimuth-Doppler domain, creating identical notches on the azimuth-Doppler plane for all ambiguous range cells to suppress clutter. However, this approach is ineffective at filtering short-range clutter, easily leading to target signals being masked by it. Improving traditional STAP technology to effectively suppress non-stationary clutter is a current hot research topic in STAP technology.

[0003] Currently, airborne radar non-stationary clutter suppression techniques are mainly divided into three categories: compensated non-stationary STAP techniques, STAP techniques based on elevation-dimensional pre-filtering, and 3D space-time adaptive processing (3D-STAP) techniques. For compensated methods, when range ambiguity exists, compensating for short-range non-stationary clutter can affect the space-time distribution of long-range clutter, severely degrading the clutter suppression performance. For STAP techniques based on elevation-dimensional pre-filtering and 3D-STAP techniques, when the number of elevation channels is small, short-range clutter easily enters from the elevation main lobe, making complete filtering difficult.

[0004] Therefore, overcoming the shortcomings of the existing technology is an urgent problem to be solved in this technical field. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a non-stationary clutter suppression method based on space-time polarization adaptive processing.

[0006] The present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a non-stationary clutter suppression method based on spatiotemporal polarization adaptive processing, comprising:

[0008] Constructing four-dimensional airborne radar echo data with polarization-elevation-azimuth-Doppler configuration;

[0009] The polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data is subjected to Doppler domain dimensionality reduction processing to obtain the processed echo data.

[0010] The covariance matrix is ​​calculated based on the processed echo data.

[0011] The covariance matrix is ​​used to calculate the space-time polarization adaptive processing weight vector;

[0012] The spatiotemporal polarization adaptive processing weight vector is applied to the echo data of each Doppler channel to obtain the processed output data.

[0013] Preferably, the constructed polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data specifically includes:

[0014] The target echo data is represented as Where a is the complex amplitude of the target signal. s t0 s a0 s e0 These are the polarization steering vector, Doppler steering vector, azimuth steering vector, and pitch steering vector of the preset target, respectively. The angle r represents the amplitude ratio between the horizontal and vertical channels of the target signal. t η0 represents the target signal power ratio between the vertical polarization channel and the horizontal polarization channel, η0 represents the phase difference between the horizontal and vertical channels of the target signal, and the superscript T indicates the transpose operation.

[0015] Based on the target echo data, determine the clutter elevation-azimuth-Doppler three-dimensional covariance matrix of the l-th range cell;

[0016] Based on the clutter elevation-azimuth-Doppler three-dimensional covariance matrix of the l-th range unit and the target echo data, determine the polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data of the l-th range unit.

[0017] Preferably, determining the clutter elevation-azimuth-Doppler three-dimensional covariance matrix of the l-th range cell based on the target echo data specifically includes:

[0018] The elevation-azimuth-Doppler three-dimensional steering vector of the i-th clutter block in the l-th range cell is in, f represents the Kronecker product. ail This represents the azimuth spatial frequency of the i-th clutter block in the l-th range cell. f represents the normalized Doppler frequency of the i-th clutter block in the l-th range cell. eilThe pitch spatial frequency of the i-th clutter block in the l-th range element is given. The phased array of the airborne radar is an M-row, N-column rectangular planar array. The spacing between the radar row and column elements is equal and d. The radar operating wavelength is λ, and the radar pulse repetition frequency is f. r The radar transmits K pulses in one pulse repetition cycle, and the aircraft's speed is v. R The angle between the antenna array and the aircraft's flight speed is θ. p The downward angle of the clutter block in the l-th range ring on the ground is The azimuth angle of the i-th clutter block in the l-th range ring on the ground is θ. i , s a (f ail ) represents the azimuth steering vector of the i-th clutter block in the l-th range cell. s is the Doppler steering vector of the i-th clutter block in the l-th range cell. e (f eil ) is the pitch dimension steering vector of the i-th clutter block in the l-th range cell;

[0019] The clutter elevation-azimuth-Doppler three-dimensional covariance matrix of the l-th range cell is: Among them ai l N represents the echo amplitude of the i-th clutter block within the l-th range cell. c N represents the number of independent clutter blocks in this range cell. r The distance fuzzing order is represented by the superscript H, which indicates the conjugate transpose operation.

[0020] Preferably, determining the polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data of the l-th range unit based on the clutter elevation-azimuth-Doppler three-dimensional covariance matrix of the l-th range unit and the target echo data specifically includes:

[0021] Determine the clutter polarization-elevation-azimuth-Doppler four-dimensional covariance matrix of the l-th range cell. Among them, I 2MNK It is a 2MNK-dimensional identity matrix. R is the noise power. p Let be the clutter polarization covariance matrix, and its mathematical expression is: r c The power ratio of the clutter signal received by the V channel and the H channel. The statistical phase difference ρ is calculated for the clutter signals in the V and H channels. c The cross-correlation coefficients for the V-channel and H-channel clutter signals;

[0022] The clutter noise polarization-elevation-azimuth-Doppler four-dimensional echo data for the l-th range cell are determined as follows: Where n∈C 2MNK×1 It is a random vector that follows a complex Gaussian distribution with a mean of 0 and a variance of 1;

[0023] The polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data for the l-th range cell is determined as x = x t +x cn,l ,l=1,2,….

[0024] Preferably, the step of performing Doppler domain dimensionality reduction processing on the polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data to obtain processed echo data specifically includes:

[0025] The Doppler filtering matrix for the k-th Doppler channel to be detected is: in, It is the center frequency of the k-th Doppler channel, and the dimension reduction matrix used for Doppler domain dimension reduction is T. k , I2、I MN These are the second-order and MN-order identity matrices, respectively;

[0026] Dimensionality reduction is performed on the polarization dual-channel data and the target spatiotemporal steering vector to obtain the processed echo data. Where, x cn,l This is the clutter noise polarization-elevation-azimuth-Doppler four-dimensional echo data for the l-th range cell.

[0027] Preferably, the step of calculating the covariance matrix based on the processed echo data specifically includes:

[0028] The echo data after dimensionality reduction of the i-th distance unit is: The clutter noise space-time polarization covariance matrix is ​​calculated using echo data from L adjacent distance cells of the unit under test.

[0029] Preferably, the step of calculating the space-time polarization adaptive processing weight vector using the covariance matrix specifically includes:

[0030] The polarization-pitch-azimuth-Doppler four-dimensional adaptive processing weights of the l-th range cell are: in, Let s0 be the reduced-dimensional spacetime steering vector of the k-th Doppler channel, and let s0 be the target spacetime steering vector of the k-th Doppler channel in the l-th range cell. This represents the clutter noise space-time polarization covariance matrix estimated using echo data from L adjacent distance cells of the cell to be detected.

[0031] Preferably, the step of applying the spatiotemporal polarization adaptive processing weight vector to the echo data of each Doppler channel to obtain processed output data specifically includes:

[0032] After spatiotemporal polarization adaptive processing, the output data of the k-th Doppler channel of the l-th range cell is:

[0033] Secondly, the present invention also provides a non-stationary clutter suppression device based on space-time polarization adaptive processing, for implementing the non-stationary clutter suppression method based on space-time polarization adaptive processing described in the first aspect, the device comprising:

[0034] At least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor for performing the non-stationary clutter suppression method based on space-time polarization adaptive processing as described in the first aspect.

[0035] Thirdly, the present invention also provides a non-volatile computer storage medium storing computer-executable instructions that are executed by one or more processors to perform the method described in the first aspect.

[0036] Fourthly, a chip is provided, comprising: a processor and an interface for calling and running a computer program stored in memory, performing methods as described in the first to second aspects and any one thereof.

[0037] Fifthly, a computer program product comprising instructions is provided, which, when executed on a computer or processor, cause the computer or processor to perform the method as described in any of the first aspects.

[0038] This invention first introduces the polarization dimension information of the echo based on 3D-STAP technology, and then performs four-dimensional joint space-time polarization adaptive processing of the echo signal, including polarization, elevation, azimuth and Doppler, to achieve suppression of non-stationary clutter. Compared with existing space-time adaptive technology, this invention can suppress short-range clutter entering from the elevation main lobe to a lower level, thereby more effectively suppressing non-stationary clutter and improving the detection probability of the target signal. Attached Figure Description

[0039] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0040] Figure 1 This is a flowchart illustrating a non-stationary clutter suppression method based on spatiotemporal polarization adaptive processing provided in an embodiment of the present invention.

[0041] Figure 2 This is a flowchart illustrating a non-stationary clutter suppression method based on spatiotemporal polarization adaptive processing provided in an embodiment of the present invention.

[0042] Figure 3 This is a schematic diagram illustrating an application scenario of a non-stationary clutter suppression method based on spatiotemporal polarization adaptive processing provided in an embodiment of the present invention.

[0043] Figure 4 This is a flowchart illustrating a non-stationary clutter suppression method based on spatiotemporal polarization adaptive processing provided in an embodiment of the present invention.

[0044] Figure 5 This is a schematic diagram of the architecture of a non-stationary clutter suppression device based on spatiotemporal polarization adaptive processing provided in an embodiment of the present invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0046] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as openly inclusive, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples; that is, although they may be incorporated into embodiments or examples using the above terms for reasons such as order and position, it does not limit them to be incorporated in combination by a single embodiment or example.

[0047] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more. Furthermore, for example, the description may use the prefix "A" or "B" to describe the same type of nouns as two independent entities. In this case, the corresponding features defined with "A" and "B" are used only to distinguish between similar entities and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features.

[0048] In the description of this invention, the expression “A and / or B” (where A and B are used to formally represent specific features) will be used. The corresponding expression includes the following three combinations: only A, only B, and a combination of A and B.

[0049] As used in this invention, “about,” “approximately,” or “approximately” includes the stated value and the average value within an acceptable range of deviation from a particular value, wherein the acceptable range of deviation is determined by a person skilled in the art taking into account the measurement under discussion and the error associated with the measurement of the particular quantity (i.e., the limitations of the measurement system).

[0050] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0051] Example 1:

[0052] Embodiment 1 of the present invention provides a non-stationary clutter suppression method based on spatiotemporal polarization adaptive processing, such as... Figure 1 As shown, it includes:

[0053] In step 201, polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data is constructed.

[0054] In step 202, the polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data is subjected to Doppler domain dimensionality reduction processing to obtain the processed echo data.

[0055] In step 203, the covariance matrix is ​​calculated based on the processed echo data.

[0056] In step 204, the covariance matrix is ​​used to calculate the space-time polarization adaptive processing weight vector.

[0057] In step 205, the spatiotemporal polarization adaptive processing weight vector is applied to the echo data of each Doppler channel to obtain the processed output data.

[0058] Among them, the constructed polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data, such as Figure 2 As shown, it specifically includes:

[0059] In step 301, the target echo data is represented as Where a is the complex amplitude of the target signal. s t0 s a0 s e0 These are the polarization steering vector, Doppler steering vector, azimuth steering vector, and pitch steering vector of the preset target, respectively. The angle r represents the amplitude ratio between the horizontal and vertical channels of the target signal. t η0 represents the target signal power ratio between the vertically polarized channel and the horizontally polarized channel, η0 represents the phase difference between the horizontal and vertical channels of the target signal, and the superscript T indicates the transpose operation.

[0060] In step 302, the clutter elevation-azimuth-Doppler three-dimensional covariance matrix of the l-th range cell is determined based on the target echo data.

[0061] In step 303, the polarization-elevation-azimuth-Doppler three-dimensional covariance matrix of the l-th range unit and the target echo data are used to determine the polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data of the l-th range unit.

[0062] In practical applications, determining the clutter elevation-azimuth-Doppler three-dimensional covariance matrix of the l-th range cell based on target echo data specifically includes:

[0063] The pitch-azimuth-Doppler three-dimensional steering vector of the i-th clutter block in the l-th range loop (also referred to as the range cell in subsequent embodiments) is: in, f represents the Kronecker product. ail Let represent the azimuth spatial frequency of the i-th clutter block in the l-th range ring. f represents the normalized Doppler frequency of the i-th clutter block in the l-th range ring. eil The pitch spatial frequency of the i-th clutter block in the l-th range loop is given. The phased array of the airborne radar is an M-row, N-column rectangular planar array. The spacing between the radar row and column elements is equal and d. The radar operating wavelength is λ, and the radar pulse repetition frequency is f. r The radar transmits K pulses in one pulse repetition cycle, and the aircraft's speed is v. RThe angle between the antenna array and the aircraft's flight speed is θ. p The downward angle of the clutter block in the l-th range ring on the ground is The azimuth angle of the i-th clutter block in the l-th range ring on the ground is θ. i , s a (f ail ) is the azimuth steering vector of the i-th clutter block in the l-th range loop. s is the Doppler steering vector of the i-th clutter block in the l-th range loop. e (f eil ) is the pitch dimension steering vector of the i-th clutter block in the l-th range loop.

[0064] The clutter elevation-azimuth-Doppler three-dimensional covariance matrix of the l-th range cell is: Among them ai l N represents the echo amplitude of the i-th clutter block within the l-th range cell. c N represents the number of independent clutter blocks in the range ring. r The distance fuzzing order is represented by the superscript H, which indicates the conjugate transpose operation.

[0065] The determination of the polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data of the l-th range unit based on the clutter elevation-azimuth-Doppler three-dimensional covariance matrix of the l-th range unit and the target echo data specifically includes:

[0066] Determine the clutter polarization-elevation-azimuth-Doppler four-dimensional covariance matrix for the l-th range loop. Among them, I 2MNK It is a 2MNK-dimensional identity matrix. R is the noise power. p Let be the clutter polarization covariance matrix, and its mathematical expression is: r c The power ratio of the clutter signal received by the V channel and the H channel. The statistical phase difference ρ is calculated for the clutter signals in the V and H channels. c This represents the cross-correlation coefficient between the V-channel and H-channel clutter signals.

[0067] The clutter noise polarization-elevation-azimuth-Doppler four-dimensional echo data for the l-th range loop are determined as follows: Where n∈C 2MNK×1 It is a random vector that follows a complex Gaussian distribution with a mean of 0 and a variance of 1.

[0068] The polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data for the l-th range loop is determined as x = x t +x cn,l,l=1,2,….

[0069] In one embodiment, the step of performing Doppler domain dimensionality reduction processing on the polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data to obtain processed echo data specifically includes:

[0070] The Doppler filtering matrix for the k-th Doppler channel to be detected is: in, ∈C K×3 , It is the center frequency of the k-th Doppler channel, and the dimension reduction matrix used for Doppler domain dimension reduction is T. k , I2、I MN These are the second-order and MN-order identity matrices, respectively.

[0071] Dimensionality reduction is performed on the polarization dual-channel data and the target spatiotemporal steering vector to obtain the processed echo data. Where, x cn,l This is the clutter noise polarization-elevation-azimuth-Doppler four-dimensional echo data for the l-th range loop.

[0072] The calculation of the covariance matrix based on the processed echo data specifically includes: the echo data after dimensionality reduction processing of the i-th distance unit is... The clutter noise space-time polarization covariance matrix is ​​calculated using echo data from L adjacent distance cells of the unit under test.

[0073] In one optional implementation, the step of calculating the spatiotemporal polarization adaptive processing weight vector using the covariance matrix specifically includes: the polarization-elevation-azimuth-Doppler four-dimensional adaptive processing weights (i.e., the spatiotemporal polarization adaptive processing weight vector) of the l-th range cell are: in, Let s0 be the reduced-dimensional spacetime steering vector of the k-th Doppler channel, and let s0 be the target spacetime steering vector of the k-th Doppler channel in the l-th range cell. This represents the clutter noise space-time polarization covariance matrix estimated using echo data from L adjacent distance cells of the cell to be detected.

[0074] The step of applying the spatiotemporal polarization adaptive processing weight vector to the echo data of each Doppler channel to obtain processed output data specifically includes: the output data of the k-th Doppler channel of the l-th range cell after spatiotemporal polarization adaptive processing is...

[0075] This embodiment utilizes information from multiple dimensions, including polarization, elevation, azimuth, and Doppler, to suppress clutter. Specifically, it first introduces polarization information of the echo based on 3D-STAP technology, and then performs four-dimensional joint spatiotemporal polarization adaptive processing on the echo signal, which achieves the suppression of non-stationary clutter. Compared with existing spatiotemporal adaptive technologies, this embodiment can suppress short-range clutter entering from the elevation main lobe to a lower level, thereby more effectively suppressing non-stationary clutter and improving the detection probability of the target signal.

[0076] Example 2:

[0077] Based on the method described in Embodiment 1, this invention combines specific application scenarios and uses technical descriptions in relevant scenarios to illustrate the implementation process of the features of this invention in those scenarios.

[0078] This embodiment uses, as follows Figure 3 The application scenario illustrated is an example where the phased array of an airborne radar is an M-row, N-column rectangular planar array. Each element is an orthogonal dual-channel polarization sensitive element, with the horizontal polarization channel denoted as the H-channel and the vertical polarization channel as the V-channel. The spacing between the radar elements in the rows and columns is equal and d, the radar operating wavelength is λ, and the radar pulse repetition frequency is f. r The radar transmits K pulses in one pulse repetition cycle, and the aircraft's altitude and speed are h and h, respectively. a and v R The Earth's equivalent radius is Re, the aircraft flies along the positive Y-axis, and the angle between the antenna array and the aircraft's flight speed is θ. p The azimuth angle of the i-th clutter block in the l-th range ring on the ground is θ. i The downward angle of the clutter block in the l-th range ring on the ground is

[0079] The non-stationary clutter suppression method based on spatiotemporal polarization adaptive processing described in this embodiment, such as Figure 4 As shown, it specifically includes:

[0080] In step 401, polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data is constructed.

[0081] In step 402, the data constructed in step 401 is subjected to Doppler domain dimensionality reduction processing.

[0082] In step 403, the covariance matrix of the echo data processed in step 402 is estimated.

[0083] In step 404, the space-time polarization adaptive processing weight vector is calculated using the echo data covariance matrix estimated in step 403.

[0084] In step 405, the spatiotemporal polarization adaptive processing weight vector calculated in step 404 is applied to the echo data of each Doppler channel to obtain the processed output data.

[0085] In step 401, the polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data is constructed, specifically including:

[0086] The target echo data can be represented as:

[0087]

[0088] Where a is the complex amplitude of the target signal. s t0 s a0 s e0 These are the polarization steering vector, Doppler steering vector, azimuth steering vector, and pitch steering vector of the preset target, respectively. The angle r represents the amplitude ratio between the horizontal and vertical channels of the target signal. t η0 represents the target signal power ratio between the vertically polarized channel and the horizontally polarized channel, η0 represents the phase difference between the horizontal and vertical channels of the target signal, and the superscript T indicates the transpose operation.

[0089] The elevation-azimuth-Doppler three-dimensional steering vector of the i-th clutter block in the l-th range loop is:

[0090]

[0091] In the formula, This represents the Kronecker product.

[0092]

[0093] Let represent the azimuth spatial frequency, normalized Doppler frequency, and elevation spatial frequency of the i-th clutter block in the l-th range loop, respectively. The azimuth, Doppler, and elevation steering vectors of this clutter block are as follows:

[0094]

[0095] The clutter elevation-azimuth-Doppler three-dimensional covariance matrix of the l-th range cell is:

[0096]

[0097] Where a il N represents the echo amplitude of the i-th clutter block within the l-th range cell. c N represents the number of independent clutter blocks in the range ring. rThe range ambiguity is indicated by the superscript H, which signifies the conjugate transpose operation. The clutter polarization-elevation-azimuth-Doppler four-dimensional covariance matrix of this range cell is:

[0098]

[0099] Among them, I 2MNK R is a 2MNK-dimensional identity matrix. p The clutter polarization covariance matrix is ​​expressed mathematically as follows:

[0100]

[0101] Where, r c The power ratio of the clutter signal received by the V channel and the H channel. The statistical phase difference ρ is calculated for the clutter signals in the V and H channels. c This represents the cross-correlation coefficient between the V-channel and H-channel clutter signals.

[0102] The clutter noise polarization-elevation-azimuth-Doppler four-dimensional echo data of the l-th range cell can be represented as:

[0103]

[0104] Where n∈C 2MNK×1 It is a random vector that follows a complex Gaussian distribution with a mean of 0 and a variance of 1.

[0105] The echo data received by the airborne radar in the l-th range cell can be represented as:

[0106] x = x t +x cn,l ,l=1,2,… (13)

[0107] In step 402, the data constructed in step 401 undergoes Doppler domain dimensionality reduction processing, specifically including:

[0108] The Doppler filtering matrix for the k-th Doppler channel to be detected is:

[0109]

[0110] in This is the center frequency of the k-th Doppler channel. The dimension reduction matrix used for Doppler domain dimensionality reduction is T. k Its mathematical expression is:

[0111]

[0112] Among them, I2, I MNThese are second-order and MN-order identity matrices, respectively. Dimensionality reduction is performed on the polarization dual-channel data and the target spatiotemporal steering vector. The dimensionality-reduced polarization dual-channel echo data of the l-th range cell can be expressed as:

[0113]

[0114] In step 403, the covariance matrix of the echo data after dimensionality reduction in step 402 is estimated, specifically including:

[0115] The echo data after dimensionality reduction of the i-th distance unit is The clutter noise space-time polarization covariance matrix estimated using echo data from L adjacent range cells of the cell to be detected can be expressed as:

[0116]

[0117] In step 404, the spatiotemporal polarization adaptive processing weight vector is calculated using the echo data covariance matrix estimated in step 403, specifically including:

[0118] The polarization-elevation-azimuth-Doppler four-dimensional adaptive processing weights of the l-th range cell can be expressed as:

[0119]

[0120] in S is the reduced-dimensional spacetime steering vector of the k-th Doppler channel, and s0 is the target spacetime steering vector of the k-th Doppler channel in the l-th range cell.

[0121] In step 405, the spatiotemporal polarization adaptive processing weight vector calculated in step 404 is applied to the echo data of each Doppler channel to obtain the processed output data. Specifically, the output result of the k-th Doppler channel of the l-th range cell after spatiotemporal polarization adaptive processing is as follows:

[0122]

[0123] This embodiment provides a non-stationary clutter suppression method using a four-dimensional adaptive space-time polarization processing technique for airborne radar. First, it introduces polarization dimension information of the echo signal based on 3D-STAP technology. Then, it performs four-dimensional joint space-time polarization adaptive processing on the echo signal (polarization-elevation-azimuth-Doppler), achieving suppression of non-stationary clutter. Compared to existing space-time adaptive techniques, the method described in this embodiment can suppress short-range clutter entering through the elevation main lobe to a lower level, thus more effectively suppressing non-stationary clutter and improving the detection probability of target signals.

[0124] Example 3:

[0125] like Figure 5 The diagram shown is a schematic representation of the architecture of a non-stationary clutter suppression device based on space-time polarization adaptive processing according to an embodiment of the present invention. This embodiment of the non-stationary clutter suppression device based on space-time polarization adaptive processing includes one or more processors 21 and a memory 22. Figure 5 Take a processor 21 as an example.

[0126] Processor 21 and memory 22 can be connected via a bus or other means. Figure 5 Taking the example of a connection between China and Israel via a bus.

[0127] The memory 22, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs and non-volatile computer-executable programs, such as the non-stationary clutter suppression method based on space-time polarization adaptive processing in Embodiment 1. The processor 21 executes the non-stationary clutter suppression method based on space-time polarization adaptive processing by running the non-volatile software programs and instructions stored in the memory 22.

[0128] Memory 22 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, memory 22 may optionally include memory remotely located relative to processor 21, which can be connected to processor 21 via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0129] The program instructions / modules are stored in the memory 22. When executed by one or more processors 21, they perform the non-stationary clutter suppression method based on space-time polarization adaptive processing in Embodiment 1.

[0130] It is worth noting that the information interaction and execution process between the modules and units in the above-mentioned device and system are based on the same concept as the processing method embodiment of the present invention. For details, please refer to the description in the method embodiment of the present invention, and will not be repeated here.

[0131] Those skilled in the art will understand that all or part of the steps in the various methods of the embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, which may include: read-only memory (ROM), random access memory (RAM), magnetic disk or optical disk, etc.

[0132] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A non-stationary clutter suppression method based on spatiotemporal polarization adaptive processing, characterized in that, include: Constructing four-dimensional airborne radar echo data with polarization-elevation-azimuth-Doppler configuration; The polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data is subjected to Doppler domain dimensionality reduction processing to obtain the processed echo data; specifically, this includes: the Doppler filtering matrix of the k-th Doppler channel to be detected is... ;in, The radar transmits the following number of pulses within one pulse repetition cycle: K , , It is the center frequency of the k-th Doppler channel, and the dimension reduction matrix used for Doppler domain dimension reduction is: , ; , These are the second-order and MN-order identity matrices, respectively; Dimensionality reduction is performed on the polarization dual-channel data and the target spatiotemporal steering vector to obtain the processed echo data. ;in, The clutter noise polarization-elevation-azimuth-Doppler four-dimensional echo data for the l-th range cell; Based on the processed echo data, the covariance matrix is ​​calculated; specifically, it includes the echo data after dimensionality reduction processing of the i-th distance unit. The clutter noise space-time polarization covariance matrix is ​​calculated using the echo data from L adjacent distance cells of the unit to be detected. ; The covariance matrix is ​​used to calculate the space-time polarization adaptive processing weight vector; specifically, it includes the polarization-elevation-azimuth-Doppler four-dimensional adaptive processing weight value of the l-th range cell. ;in, Let be the reduced-dimensional spacetime steering vector of the k-th Doppler channel, and let be the target spacetime steering vector of the k-th Doppler channel in the l-th range cell. , This represents the clutter noise space-time polarization covariance matrix estimated using echo data from L adjacent distance cells of the cell to be detected; The spatiotemporal polarization adaptive processing weight vector is applied to the echo data of each Doppler channel to obtain the processed output data.

2. The non-stationary clutter suppression method based on spatiotemporal polarization adaptive processing according to claim 1, characterized in that, The constructed polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data specifically includes: The target echo data is represented as ;in, For the complex amplitude of the target signal, , , , These are the polarization steering vector, Doppler steering vector, azimuth steering vector, and pitch steering vector of the preset target, respectively. This angle represents the amplitude ratio between the horizontal and vertical channels of the target signal. This represents the target signal power ratio between the vertically polarized channel and the horizontally polarized channel. The phase difference between the horizontal and vertical channels of the target signal is represented by the superscript T, which indicates the transpose operation. Based on the target echo data, determine the clutter elevation-azimuth-Doppler three-dimensional covariance matrix of the l-th range cell; Based on the clutter elevation-azimuth-Doppler three-dimensional covariance matrix of the l-th range unit and the target echo data, determine the polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data of the l-th range unit.

3. The non-stationary clutter suppression method based on spatiotemporal polarization adaptive processing according to claim 2, characterized in that, The step of determining the clutter elevation-azimuth-Doppler three-dimensional covariance matrix of the l-th range cell based on the target echo data specifically includes: The elevation-azimuth-Doppler three-dimensional steering vector of the i-th clutter block in the l-th range cell is ;in, Represents the Kronecker product. This represents the azimuth spatial frequency of the i-th clutter block in the l-th range cell. This represents the normalized Doppler frequency of the i-th clutter block in the l-th range cell. Let represent the pitch-dimensional spatial frequency of the i-th clutter block in the l-th range cell. The phased array of the airborne radar is... M OK N A rectangular planar array of columns, with equal spacing between radar row and column elements and a spacing of [missing information]. The radar's operating wavelength is The radar pulse repetition frequency is The speed of the carrier aircraft is The angle between the antenna array and the aircraft's flight speed is The first on the ground l The downward angle of the clutter block in the range ring is The first on the ground l The azimuth angle of the i-th clutter block in the range ring is , , , ; Let be the azimuth guidance vector of the i-th clutter block in the l-th range cell. The Doppler steering vector of the i-th clutter block in the l-th range cell. The pitch dimension steering vector of the i-th clutter block in the l-th range cell; The clutter elevation-azimuth-Doppler three-dimensional covariance matrix of the l-th range cell is: ;in Let be the echo amplitude of the i-th clutter block within the l-th range cell. This represents the number of independent clutter blocks within that range cell. The distance fuzzing order is represented by the superscript H, which indicates the conjugate transpose operation.

4. The non-stationary clutter suppression method based on spatiotemporal polarization adaptive processing according to claim 3, characterized in that, The determination of the polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data of the l-th range unit based on the clutter elevation-azimuth-Doppler three-dimensional covariance matrix of the l-th range unit and the target echo data specifically includes: Determine the clutter polarization-elevation-azimuth-Doppler four-dimensional covariance matrix of the l-th range cell. ;in, It is a 2MNK-dimensional identity matrix. For noise power, Let be the clutter polarization covariance matrix, and its mathematical expression is: , The power ratio of the clutter signal received by the V channel and the H channel. Statistical phase difference between clutter signals in channels V and H. The cross-correlation coefficients for the V-channel and H-channel clutter signals; The clutter noise polarization-elevation-azimuth-Doppler four-dimensional echo data for the l-th range cell are determined as follows: ;in It is a random vector that follows a complex Gaussian distribution with a mean of 0 and a variance of 1; The polarization-elevation-azimuth-Doppler four-dimensional airborne radar echo data of the l-th range cell is determined as follows: .

5. The non-stationary clutter suppression method based on spatiotemporal polarization adaptive processing according to claim 1, characterized in that, The step of applying the spatiotemporal polarization adaptive processing weight vector to the echo data of each Doppler channel to obtain processed output data specifically includes: After spatiotemporal polarization adaptive processing, the output data of the k-th Doppler channel of the l-th range cell is: .

6. A non-stationary clutter suppression device based on spatiotemporal polarization adaptive processing, characterized in that, include: At least one processor; And a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the processor for performing the non-stationary clutter suppression method based on spatiotemporal polarization adaptive processing as described in any one of claims 1-5.

7. A non-volatile computer storage medium, characterized in that, The computer storage medium stores computer-executable instructions that are executed by one or more processors to perform the method described in any one of claims 1-5.

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