Clutter compensation method and system for airborne early warning radar system under the influence of yaw angle

Abstract

The present invention provides a method and system for compensating clutter in an airborne early warning radar system under the influence of yaw angle, comprising: acquiring multi-channel airborne early warning radar echo signal data; estimating the space-time power spectrum of the echo signal data and calculating an initial yaw angle estimate based on the Doppler center shift of the space-time spectrum; determining a yaw angle search interval based on the initial yaw angle estimate, calculating the value of a one-dimensional cost function, and obtaining a final yaw angle estimate; and constructing a non-stationary compensation function based on the yaw angle estimate to implement distance-dependent compensation processing in a post-Doppler manner, thereby obtaining echo data after non-stationary compensation. The method proposed in the present invention can effectively achieve distance-dependent compensation processing for clutter signals, overcoming the problem that traditional clutter non-stationary compensation technologies fail to consider the non-stationary compensation problem of a positive side-looking radar system under the influence of an unknown yaw angle.

Description

Technical Field

[0001] The present invention relates to the technical field of clutter non-stationary compensation, and more particularly to a method and system for compensating clutter in an airborne early warning radar system under the influence of yaw angle. In particular, the present invention relates to a method for compensating clutter non-stationary compensation in a front-facing side-view airborne early warning radar system under the influence of yaw angle. Background Art

[0002] For early warning radar systems operating in a straight-side view, the system will inevitably introduce an equivalent yaw angle due to the influence of actual non-ideal environmental factors such as wind disturbance and airflow, causing the carrier aircraft's heading to deviate from the radar antenna array direction. This will cause clutter to become range-dependent, seriously affecting the subsequent space-time adaptive clutter suppression processing and moving target detection performance. To address the range dependence of clutter signals and ensure the subsequent effective STAP clutter suppression processing and moving target detection, some processing methods based on estimating the center offset of the clutter mainlobe spectrum and compensating for it have been proposed, such as the Doppler wrapping (DW) method and the Angle Doppler compensation (ADC) method, which can effectively compensate for the range non-stationary error at the center of the clutter spectrum. Interpolation transformation-based non-stationary compensation methods use a transformation matrix to equivalently map clutter signals of different range units to a reference clutter subspace to achieve clutter non-uniform compensation processing.

[0003] The above methods are based on non-stationary compensation schemes proposed for forward-looking or bistatic systems. Therefore, they can achieve non-stationary clutter compensation using prior information about the known system configuration. However, these methods do not consider the effects of yaw angle on forward-looking radar systems, as the yaw angle is random and unknown.

[0004] In summary, there is an urgent need in the market for a clutter compensation method and system for an airborne early warning radar system under the influence of an unknown yaw angle, which can take into account the non-stationary compensation problem of a positive side-looking radar system under the influence of an unknown yaw angle. Summary of the Invention

[0005] In view of the defects in the prior art, the object of the present invention is to provide a method and system for clutter compensation of an airborne early warning radar system under the influence of yaw angle.

[0006] According to the present invention, a method for compensating clutter of an airborne early warning radar system under the influence of a yaw angle is provided, comprising:

[0007] Step S1: Acquire multi-channel airborne early warning radar echo signal data;

[0008] Step S2: estimating the space-time power spectrum of the echo signal data, and calculating an initial estimated value of the yaw angle according to the Doppler center shift of the space-time spectrum;

[0009] Step S3: determining a yaw angle search interval according to the initial estimated value of the yaw angle, calculating a value of a one-dimensional cost function, and obtaining a final yaw angle estimation result;

[0010] Step S4: Based on the yaw angle estimation result, a non-stationary compensation function is constructed to implement distance-dependent compensation processing in the post-Doppler, thereby obtaining echo data after non-stationary compensation.

[0011] Preferably, the initial estimated value of the yaw angle is calculated based on the Doppler center offset of the space-time spectrum, and the formula is as follows:

[0012]

[0013] Where, represents the initial estimate of the yaw angle, represents the normalized Doppler frequency center estimated from the Doppler output peak, acos() represents the arc cosine function, λ represents the wavelength, P RF represents the pulse repetition frequency, v represents the radar platform operating speed, θ el,c represents the viewing angle under the center of the radar beam, θ azi,bc Indicates the azimuth of the radar beam center.

[0014] Preferably, step S3 includes:

[0015] Step S3.1: Obtain the current yaw angle search interval based on the initial estimation result of the yaw angle Where [-δ, δ] represents the search range determined near the initial estimation result of the yaw angle;

[0016] Step S3.2: Calculate the spatial center frequency of the current space-time power spectrum using the following formula:

[0017]

[0018] Where, Indicates that the yaw angle value is being searched. The spatial frequency center value at , d represents the azimuth adjacent channel spacing of the multi-channel radar system, θ el,c represents the viewing angle under the center of the radar beam, θ azi,bc represents the radar beam center azimuth, represents the yaw angle value variable within the search interval, and λ represents the wavelength;

[0019] Step S3.3: Calculate the clutter space-time power spectrum Doppler slicing function, the formula is as follows:

[0020]

[0021] Where, Indicates using different search yaw angle values The compensated clutter space-time power spectrum Doppler slicing function, () -1 represents the matrix inversion operation, Indicates the spatial frequency The space-time two-dimensional joint steering vector at the value, Indicates the use of The estimated clutter covariance matrix after compensation processing, f a represents the Doppler frequency variable, H represents the system platform height, P RF Indicates the system pulse repetition frequency;

[0022] Step S3.4: Traverse all yaw angles in the current search interval to obtain the one-dimensional cost function values under different yaw angle values in the yaw angle search interval. The calculation formula is as follows:

[0023]

[0024] Where, Indicates the final estimated yaw angle value, B 3dB () represents the 3-dB normalized Doppler bandwidth acquisition function;

[0025] Step S3.5: According to the value of the one-dimensional cost function, the yaw angle value at the valley point is obtained as the final yaw angle estimation result.

[0026] Preferably, the calculation formula for constructing the non-stationary compensation function is as follows:

[0027]

[0028] Where H comp () represents the non-stationary compensation function, f a represents the Doppler frequency variable, Indicates the final estimated yaw angle value, j represents an imaginary number λ represents the wavelength, N represents the number of azimuth channels of the radar system, v represents the operating speed of the radar platform, d represents the physical spacing between radar antenna channels, θ el, Indicates the lower viewing angle value processed by different distance units calculated using the system prior information.

[0029] Preferably, the non-stationary compensation function is used to transform the echo data into the post-Doppler domain to implement non-stationary compensation processing, and finally the multi-channel echo data after clutter non-stationary compensation is output.

[0030] According to the present invention, a clutter compensation system for an airborne early warning radar system under the influence of a yaw angle is provided, comprising:

[0031] Module M1: Acquire multi-channel airborne early warning radar echo signal data;

[0032] Module M2: estimating the space-time power spectrum of the echo signal data, and calculating an initial estimated value of the yaw angle according to the Doppler center shift of the space-time spectrum;

[0033] Module M3: determining a yaw angle search interval according to the initial estimated value of the yaw angle, calculating a value of a one-dimensional cost function, and obtaining a final yaw angle estimation result;

[0034] Module M4: Based on the yaw angle estimation result, a non-stationary compensation function is constructed to implement distance-dependent compensation processing in the post-Doppler, thereby obtaining echo data after non-stationary compensation.

[0035] Preferably, the initial estimated value of the yaw angle is calculated based on the Doppler center offset of the space-time spectrum, and the formula is as follows:

[0036]

[0037] Where, represents the initial estimate of the yaw angle, represents the normalized Doppler frequency center estimated from the Doppler output peak, acos() represents the arc cosine function, λ represents the wavelength, P RF represents the pulse repetition frequency, v represents the radar platform operating speed, θ el,c represents the viewing angle under the center of the radar beam, θ azi,bc Indicates the azimuth of the radar beam center.

[0038] Preferably, module M3 comprises:

[0039] Module M3.1: Obtain the current yaw angle search interval based on the initial estimation result of the yaw angle Where [-δ, δ] represents the search range determined near the initial estimation result of the yaw angle;

[0040] Module M3.2: Calculate the spatial center frequency of the current space-time power spectrum. The formula is as follows:

[0041]

[0042] Where, Indicates that the yaw angle value is being searched. The spatial frequency center value at , d represents the azimuth adjacent channel spacing of the multi-channel radar system, θ el,c represents the viewing angle under the center of the radar beam, θ azi,bc represents the radar beam center azimuth, represents the yaw angle value variable within the search interval, and λ represents the wavelength;

[0043] Module M3.3: Calculate the Doppler slicing function of the clutter space-time power spectrum. The formula is as follows:

[0044]

[0045] Where, Indicates using different search yaw angle values The compensated clutter space-time power spectrum Doppler slicing function, () -1 represents the matrix inversion operation, Indicates the spatial frequency The space-time two-dimensional joint steering vector at the value, Indicates the use of The estimated clutter covariance matrix after compensation processing, f a represents the Doppler frequency variable, H represents the system platform height, P RF Indicates the system pulse repetition frequency;

[0046] Module M3.4: Traverse all yaw angles in the current search interval and obtain the one-dimensional cost function values under different yaw angle values in the yaw angle search interval. The calculation formula is as follows:

[0047]

[0048] Where, Indicates the final estimated yaw angle value, B 3dB () represents the 3-dB normalized Doppler bandwidth acquisition function;

[0049] Module M3.5: According to the value of the one-dimensional cost function, the yaw angle value at the valley point is obtained as the final yaw angle estimation result.

[0050] Preferably, the calculation formula for constructing the non-stationary compensation function is as follows:

[0051]

[0052] Where H comp () represents the non-stationary compensation function, f a represents the Doppler frequency variable, Indicates the final estimated yaw angle value, j represents an imaginary number λ represents the wavelength, N represents the number of azimuth channels of the radar system, v represents the operating speed of the radar platform, d represents the physical spacing between radar antenna channels, θ el, Indicates the lower viewing angle value processed by different distance units calculated using the system prior information.

[0053] Preferably, the non-stationary compensation function is used to transform the echo data into the post-Doppler domain to implement non-stationary compensation processing, and finally the multi-channel echo data after clutter non-stationary compensation is output.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] 1. The method proposed in the present invention can effectively realize the distance-dependent compensation processing of clutter signals, overcoming the problem that traditional clutter non-stationary compensation technology does not consider the non-stationary compensation problem of the front-side looking radar system under the influence of unknown yaw angle.

[0056] 2. The present invention utilizes the offset and broadening characteristics of the two-dimensional space-time power spectrum of the echo signal under the influence of the yaw angle to achieve accurate estimation of the unknown yaw angle, and then effectively realizes the non-stationary compensation processing of clutter in the post-Doppler domain by constructing a non-stationary compensation function. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0058] Figure 1 This is a processing flow chart of the noise non-stationary compensation method provided in an embodiment of the present invention.

[0059] Figure 2a This is a space-time two-dimensional power spectrum diagram of the clutter signal with a yaw angle of 10 degrees without non-stationary compensation processing in the present invention.

[0060] Figure 2b This is a schematic diagram of the preliminary estimation results of the yaw angle obtained by implementing the present invention.

[0061] Figure 2c This is a schematic diagram of the final yaw angle estimation result obtained by implementing the present invention.

[0062] Figure 2d The final clutter space-time two-dimensional power spectrum after non-stationary compensation processing of the clutter signal with a yaw angle of 10 degrees is performed for the implementation of the present invention. DETAILED DESCRIPTION

[0063] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0064] According to the present invention, a method for compensating clutter of an airborne early warning radar system under the influence of a yaw angle is provided. Figure 1 As shown, including:

[0065] Step S1: Acquire multi-channel airborne early warning radar echo signal data.

[0066] Step S2: Estimate the space-time power spectrum of the echo signal data and calculate the initial estimated value of the yaw angle based on the Doppler center offset of the space-time spectrum. The initial estimated value of the yaw angle is calculated based on the Doppler center offset of the space-time spectrum. The formula is as follows:

[0067]

[0068] Where, represents the initial estimate of the yaw angle, represents the normalized Doppler frequency center estimated from the Doppler output peak, acos() represents the arc cosine function, λ represents the wavelength, P RF represents the pulse repetition frequency, v represents the radar platform operating speed, θ el,c represents the viewing angle under the center of the radar beam, θ azi,bc Indicates the azimuth of the radar beam center.

[0069] Step S3: Determine the precise yaw angle search interval based on the initial yaw angle estimate, calculate the value of the one-dimensional cost function, and obtain the final precise yaw angle estimation result. Step S3 includes:

[0070] Step S3.1: Based on the initial estimation result of the yaw angle, obtain the current precise yaw angle search range where [-δ, δ] represents the precise search range determined around the initial estimate of the yaw angle.

[0071] Step S3.2: Calculate the spatial center frequency of the current space-time power spectrum using the following formula:

[0072]

[0073] Where, Indicates that the yaw angle value is being searched. The spatial frequency center value at , d represents the azimuth adjacent channel spacing of the multi-channel radar system, θ el,c represents the viewing angle under the center of the radar beam, θ azi,bc represents the radar beam center azimuth, represents the variable of the yaw angle value within the precise search interval, and λ represents the wavelength.

[0074] Step S3.3: Calculate the clutter space-time power spectrum Doppler slicing function, the formula is as follows:

[0075]

[0076] Where, Indicates using different search yaw angle values The compensated clutter space-time power spectrum Doppler slicing function, () -1 represents the matrix inversion operation, Indicates the spatial frequency The space-time two-dimensional joint steering vector at the value, Indicates the use of The estimated clutter covariance matrix after compensation processing, f a represents the Doppler frequency variable, H represents the system platform height, P RF Indicates the system pulse repetition frequency.

[0077] Step S3.4: Traverse all yaw angles in the current precise search interval to obtain the one-dimensional cost function values under different yaw angle values in the yaw angle precise search interval. The calculation formula is as follows:

[0078]

[0079] Where, Indicates the final estimated yaw angle value, B 3dB () represents the 3-dB normalized Doppler bandwidth acquisition function.

[0080] Step S3.5: According to the one-dimensional cost function, the yaw angle value at the valley point is obtained as the final yaw angle estimation result.

[0081] Step S4: Based on the accurate yaw angle estimation result, a non-stationary compensation function is constructed to implement distance-dependent compensation processing in the post-Doppler, thereby obtaining echo data after non-stationary compensation. The calculation formula for constructing the non-stationary compensation function is as follows:

[0082]

[0083] Where H comp () represents the non-stationary compensation function, f a represents the Doppler frequency variable, Indicates the final estimated yaw angle value, j represents an imaginary number λ represents the wavelength, N represents the number of azimuth channels of the radar system, v represents the operating speed of the radar platform, d represents the physical spacing between radar antenna channels, θ el, The value of the lower viewing angle calculated using the system's prior information for different range units is shown in Figure 2. Using the non-stationary compensation function, the echo data is transformed into the post-Doppler domain to implement non-stationary compensation, ultimately outputting multi-channel echo data after clutter non-stationary compensation.

[0084] Furthermore, the compensation method of the present invention is simulated on the MATLAB R2018b simulation platform, which is specifically described as follows:

[0085] First, the original echo data of the N-channel airborne early warning radar system is input, where N=8 is taken as an example for explanation.

[0086] Then, the original echo data of the N channels are processed by range pulse compression to estimate the two-dimensional space-time power spectrum. The initial estimation result of the yaw angle is calculated according to formula (1) based on the two-dimensional space-time power spectrum.

[0087] Next, based on the calculated initial estimation result of the yaw angle, the precise search interval of the yaw angle is determined, and the one-dimensional cost function values corresponding to different yaw angles in the precise search interval of the yaw angle are calculated according to formula (2). Specifically, the yaw angle in the current precise search interval is obtained, and a non-stationary compensation function is established according to formula (5) to compensate the echo signal. The spatial center frequency of the current space-time power spectrum is calculated according to formula (3), and the current space-time two-dimensional power spectrum is calculated according to formula (4) to obtain the 3dB main lobe width of the one-dimensional Doppler spectrum at the current spatial center frequency. All yaw angles in the current precise search interval are traversed to obtain the one-dimensional cost function values under different yaw angle values in the precise search interval of the yaw angle.

[0088] Next, according to the value of the one-dimensional cost function, the yaw angle value at the valley point is obtained as the final yaw angle estimation result.

[0089] Finally, the final estimated result of the yaw angle is used to establish a non-stationary compensation function according to formula (5). After the echo signal is processed with non-stationary compensation, the multi-channel early warning radar echo data after non-stationary compensation is output.

[0090] According to the above specific implementation steps, simulation is performed on the MATLAB R2018b simulation platform, and the space-time two-dimensional spectrum after non-stationary compensation processing is obtained according to the present invention. Figure 2a This is the space-time spectrum of the clutter signal with a yaw angle of 10 degrees without non-stationary compensation processing; Figure 2b is a preliminary estimation result of the yaw angle according to the present invention; Figure 2c is the final estimation result of the yaw angle according to the present invention; Figure 2d The final clutter space-time two-dimensional power spectrum after the compensation of the present invention is shown in FIG. The results show that the method provided by the present invention can effectively achieve non-stationary compensation processing of clutter signals, thereby ensuring the performance of subsequent space-time adaptive clutter suppression processing.

[0091] The present invention also provides a clutter compensation system for an airborne early warning radar system under the influence of a yaw angle. Those skilled in the art can implement the clutter compensation system for an airborne early warning radar system under the influence of a yaw angle by executing the steps of the clutter compensation method for an airborne early warning radar system under the influence of a yaw angle. That is, the clutter compensation method for an airborne early warning radar system under the influence of a yaw angle can be understood as a preferred implementation of the clutter compensation system for an airborne early warning radar system under the influence of a yaw angle.

[0092] According to the present invention, a clutter compensation system for an airborne early warning radar system under the influence of a yaw angle is provided, comprising:

[0093] Module M1: Acquires multi-channel airborne early warning radar echo signal data.

[0094] Module M2: Estimate the space-time power spectrum of the echo signal data and calculate the initial estimated value of the yaw angle based on the Doppler center offset of the space-time spectrum. The initial estimated value of the yaw angle is calculated based on the Doppler center offset of the space-time spectrum. The formula is as follows:

[0095]

[0096] Where, represents the initial estimate of the yaw angle, represents the normalized Doppler frequency center estimated from the Doppler output peak, acos() represents the arc cosine function, λ represents the wavelength, P RF represents the pulse repetition frequency, v represents the radar platform operating speed, θ el,c represents the viewing angle under the center of the radar beam, θ azi,bc Indicates the azimuth of the radar beam center.

[0097] Module M3: Determine the precise yaw angle search interval based on the initial yaw angle estimate, calculate the value of the one-dimensional cost function, and obtain the final precise yaw angle estimate. Module M3 includes:

[0098] Module M3.1: Get the current precise yaw angle search range based on the initial estimation result of the yaw angle where [-δ, δ] represents the precise search range determined around the initial estimate of the yaw angle.

[0099] Module M3.2: Calculate the spatial center frequency of the current space-time power spectrum. The formula is as follows:

[0100]

[0101] Where, Indicates that the yaw angle value is being searched. The spatial frequency center value at , d represents the azimuth adjacent channel spacing of the multi-channel radar system, θ el,c represents the viewing angle under the center of the radar beam, θ azi,bc represents the radar beam center azimuth, represents the variable of the yaw angle value within the precise search interval, and λ represents the wavelength.

[0102] Module M3.3: Calculate the Doppler slicing function of the clutter space-time power spectrum. The formula is as follows:

[0103]

[0104] Where, Indicates using different search yaw angle values The compensated clutter space-time power spectrum Doppler slicing function, () -1 represents the matrix inversion operation, Indicates the spatial frequency The space-time two-dimensional joint steering vector at the value, Indicates the use of The estimated clutter covariance matrix after compensation processing, f a represents the Doppler frequency variable, H represents the system platform height, P RF Indicates the system pulse repetition frequency.

[0105] Module M3.4: Traverse all yaw angles in the current precise search interval and obtain the one-dimensional cost function values under different yaw angle values in the yaw angle precise search interval. The calculation formula is as follows:

[0106]

[0107] Where, Indicates the final estimated yaw angle value, B 3dB () represents the 3-dB normalized Doppler bandwidth acquisition function.

[0108] Module M3.5: According to the one-dimensional cost function, the yaw angle at the valley point is obtained as the final yaw angle estimation result.

[0109] Module M4: Based on the accurate yaw angle estimation results, a non-stationary compensation function is constructed to implement distance-dependent compensation processing in the post-Doppler, thereby obtaining echo data after non-stationary compensation. The calculation formula for constructing the non-stationary compensation function is as follows:

[0110]

[0111] Where H comp () represents the non-stationary compensation function, f a represents the Doppler frequency variable, Indicates the final estimated yaw angle value, j represents an imaginary number λ represents the wavelength, N represents the number of azimuth channels of the radar system, v represents the operating speed of the radar platform, d represents the physical spacing between radar antenna channels, θ el, The value of the lower viewing angle calculated using the system's prior information for different range units is shown in Figure 2. Using the non-stationary compensation function, the echo data is transformed into the post-Doppler domain to implement non-stationary compensation, ultimately outputting multi-channel echo data after clutter non-stationary compensation.

[0112] Those skilled in the art will appreciate that, in addition to implementing the system, device, and various modules provided by the present invention in purely computer-readable program code, it is entirely possible to implement the same program in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, embedded microcontrollers, and the like by logically programming the method steps. Therefore, the system, device, and various modules provided by the present invention can be considered a hardware component, and the modules included therein for implementing various programs can also be considered structures within the hardware component; the modules for implementing various functions can also be considered both software programs for implementing the method and structures within the hardware component.

[0113] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A method for compensating clutter in an airborne early warning radar system under the influence of yaw angle, characterized in that: include: Step S1: Acquire multi-channel airborne early warning radar echo signal data; Step S2: estimating the space-time power spectrum of the echo signal data, and calculating an initial estimated value of the yaw angle according to the Doppler center shift of the space-time spectrum; Step S3: determining a yaw angle search interval according to the initial estimated value of the yaw angle, calculating a value of a one-dimensional cost function, and obtaining a final yaw angle estimation result; Step S4: Based on the yaw angle estimation result, a non-stationary compensation function is constructed to implement distance-dependent compensation processing in the post-Doppler, thereby obtaining echo data after non-stationary compensation.

2. The clutter compensation method for an airborne early warning radar system under the influence of yaw angle according to claim 1, characterized in that: The initial estimated value of the yaw angle is calculated based on the Doppler center offset of the space-time spectrum, and the formula is as follows: Where, represents the initial estimate of the yaw angle, represents the normalized Doppler frequency center estimated from the Doppler output peak, acos( ) represents the arc cosine function, λ represents the wavelength, P RF represents the pulse repetition frequency, v represents the radar platform operating speed, θ el,bc represents the viewing angle under the center of the radar beam, θ azi,bc Indicates the azimuth of the radar beam center.

3. The clutter compensation method for an airborne early warning radar system under the influence of yaw angle according to claim 1, characterized in that: Step S3 includes: Step S3.1: Obtain the current yaw angle search interval based on the initial estimation result of the yaw angle Where [-δ, δ] represents the search range determined near the initial estimation result of the yaw angle; Step S3.2: Calculate the spatial center frequency of the current space-time power spectrum using the following formula: Where, Indicates that the yaw angle value is being searched. The spatial frequency center value at , d represents the azimuth adjacent channel spacing of the multi-channel radar system, θ el,bc represents the viewing angle under the center of the radar beam, θ azi,bc represents the radar beam center azimuth, represents the yaw angle value variable within the search interval, and λ represents the wavelength; Step S3.3: Calculate the clutter space-time power spectrum Doppler slicing function, the formula is as follows: Where, Shows the use of different search yaw angle values The compensated clutter space-time power spectrum Doppler slicing function, ( ) -1 represents the matrix inversion operation, Indicates the spatial frequency The space-time two-dimensional joint steering vector at the value, Indicates the use of The estimated clutter covariance matrix after compensation processing, f a represents the Doppler frequency variable, H represents the system platform height, P RF Indicates the system pulse repetition frequency; Step S3.4: Traverse all yaw angles in the current search interval to obtain the one-dimensional cost function values under different yaw angle values in the yaw angle search interval. The calculation formula is as follows: Where, Indicates the final estimated yaw angle value, B 3dB ( ) represents the 3-dB normalized Doppler bandwidth acquisition function; Step S3.5: According to the value of the one-dimensional cost function, the yaw angle value at the valley point is obtained as the final yaw angle estimation result.

4. The clutter compensation method for an airborne early warning radar system under the influence of yaw angle according to claim 1, characterized in that: The calculation formula for constructing the non-stationary compensation function is as follows: Where H comp ( ) represents the non-stationary compensation function, f a represents the Doppler frequency variable, Indicates the final estimated yaw angle value, j is an imaginary number λ represents the wavelength, N represents the number of azimuth channels of the radar system, v represents the operating speed of the radar platform, d represents the physical spacing between radar antenna channels, θ el,p Indicates the lower viewing angle value processed by different distance units calculated using the system prior information.

5. The clutter compensation method for an airborne early warning radar system under the influence of yaw angle according to claim 4, characterized in that: The non-stationary compensation function is used to transform the echo data into the post-Doppler domain to implement non-stationary compensation processing, and finally the multi-channel echo data after the clutter non-stationary compensation is output.

6. A clutter compensation system for an airborne early warning radar system under the influence of yaw angle, characterized in that: include: Module M1: Acquire multi-channel airborne early warning radar echo signal data; Module M2: estimating the space-time power spectrum of the echo signal data, and calculating an initial estimated value of the yaw angle according to the Doppler center shift of the space-time spectrum; Module M3: determining a yaw angle search interval according to the initial estimated value of the yaw angle, calculating a value of a one-dimensional cost function, and obtaining a final yaw angle estimation result; Module M4: Based on the yaw angle estimation result, a non-stationary compensation function is constructed to implement distance-dependent compensation processing in the post-Doppler, thereby obtaining echo data after non-stationary compensation.

7. The clutter compensation system for an airborne early warning radar system under the influence of yaw angle according to claim 6, characterized in that: The initial estimated value of the yaw angle is calculated based on the Doppler center offset of the space-time spectrum, and the formula is as follows: Where, represents the initial estimate of the yaw angle, represents the normalized Doppler frequency center estimated from the Doppler output peak, acos( ) represents the arc cosine function, λ represents the wavelength, P RF represents the pulse repetition frequency, v represents the radar platform operating speed, θ el,bc represents the viewing angle under the center of the radar beam, θ azi,bc Indicates the radar beam center azimuth.

8. The clutter compensation system for an airborne early warning radar system under the influence of yaw angle according to claim 6, characterized in that: Module M3 includes: Module M3.1: Obtain the current yaw angle search interval based on the initial estimation result of the yaw angle Where [-δ, δ] represents the search range determined near the initial estimation result of the yaw angle; Module M3.2: Calculate the spatial center frequency of the current space-time power spectrum. The formula is as follows: Where, Indicates that the yaw angle value is being searched. The spatial frequency center value at , d represents the azimuth adjacent channel spacing of the multi-channel radar system, θ el,bc represents the viewing angle under the center of the radar beam, θ azi,bc represents the radar beam center azimuth, represents the yaw angle value variable within the search interval, and λ represents the wavelength; Module M3.3: Calculate the Doppler slicing function of the clutter space-time power spectrum. The formula is as follows: Where, Indicates using different search yaw angle values The compensated clutter space-time power spectrum Doppler slicing function, ( ) -1 represents the matrix inversion operation, Indicates the spatial frequency The space-time two-dimensional joint steering vector at the value, Indicates the use of The estimated clutter covariance matrix after compensation processing, f a represents the Doppler frequency variable, H represents the system platform height, P RF Indicates the system pulse repetition frequency; Module M3.4: Traverse all yaw angles in the current search interval and obtain the one-dimensional cost function values under different yaw angle values in the yaw angle search interval. The calculation formula is as follows: Where, Indicates the final estimated yaw angle value, B 3dB ( ) represents the 3-dB normalized Doppler bandwidth acquisition function; Module M3.5: According to the value of the one-dimensional cost function, the yaw angle value at the valley point is obtained as the final yaw angle estimation result.

9. The clutter compensation system for an airborne early warning radar system under the influence of yaw angle according to claim 6, characterized in that: The calculation formula for constructing the non-stationary compensation function is as follows: Where H comp ( ) represents the non-stationary compensation function, f a represents the Doppler frequency variable, Indicates the final estimated yaw angle value, j represents an imaginary number λ represents the wavelength, N represents the number of azimuth channels of the radar system, v represents the operating speed of the radar platform, d represents the physical spacing between radar antenna channels, θ el,p Indicates the lower viewing angle value processed by different distance units calculated using the system prior information.

10. The clutter compensation system for an airborne early warning radar system under the influence of yaw angle according to claim 9, characterized in that: The non-stationary compensation function is used to transform the echo data into the post-Doppler domain to implement non-stationary compensation processing, and finally the multi-channel echo data after the clutter non-stationary compensation is output.

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