Space-time adaptive processing method for airborne broadband radar based on frequency domain compensation

Abstract

The application discloses a kind of space-time adaptive processing methods of airborne broadband radar based on frequency domain compensation, comprising: obtaining target echo signal;The distance sampling is carried out to broadband echo signal, and the sampled target echo signal is obtained;The Fourier transform is carried out to the sampled target echo signal, and the target echo signal in distance frequency domain is obtained;The target echo signal after matching filtering is obtained by carrying out matching filtering processing to the target echo signal in distance frequency domain;According to the preset phase compensation factor, the envelope movement between each array element and each pulse of the target echo signal after matching filtering is compensated, and the compensated target echo signal is obtained;The inverse Fourier transform is carried out to the compensated target echo signal, and the target echo signal in distance time domain is obtained;The echo signal in distance time domain is carried out space-time adaptive processing, and clutter and noise are inhibited.The application can improve effect more obvious.

Description

Technical Field

[0001] This invention belongs to the field of radar signal processing technology, specifically relating to a space-time adaptive processing method for airborne broadband radar based on frequency domain compensation. Background Technology

[0002] Airborne radar can mitigate the limitations imposed by Earth's curvature and terrain, enabling the detection of distant low-altitude targets and the acquisition of more scene information. However, it also faces a highly complex electromagnetic environment, the most significant being the influence of ground clutter. Ground clutter is widely distributed and covers a large area, with varying velocities from different directions, leading to two-dimensional coupling in both space and time. This results in Doppler broadening of the clutter spectrum, which severely impacts target detection performance. Therefore, space-time adaptive processing combined with adaptive filtering in both space and time dimensions is recognized as a key technology in airborne radar signal processing, effectively matching clutter signals.

[0003] Traditional space-time adaptive processing methods are based on the narrowband assumption, which assumes that the envelopes of the echo signals are consistent between array elements and between pulses. However, for airborne broadband radars, as the bandwidth increases, the resolution of the radar system significantly improves, making it impossible to ignore the aperture transit time or the distance traveled within a coherent processing time as with narrowband radars. In extreme cases, the target may traverse multiple range cells, resulting in energy reduction after coherent accumulation, which is detrimental to target detection. Simultaneously, the frequency variation of clutter ridges cannot be ignored, leading to a significant broadening of the clutter spectrum, increased clutter complexity, and a decline in the clutter suppression performance of traditional STAP techniques.

[0004] In related technologies, Hoffman et al. proposed a STAP method for airborne broadband radar based on subband partitioning in 2000. This method first transforms the echo data to the range frequency domain, then divides the transformed data into several subbands, processes each subband using narrowband STAP, and finally transforms all the results back to the time domain and merges them. When the number of subbands is large enough, the subband method can achieve near-optimal performance. However, since each subband requires independent selection of training samples, estimation and inversion of the covariance matrix, and spatiotemporal adaptive processing, this method introduces a large amount of computation and a high demand for training samples.

[0005] Therefore, it is urgent to improve the defects existing in the current technology. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, this invention provides a space-time adaptive processing method for airborne broadband radar based on frequency domain compensation. The technical problem to be solved by this invention is achieved through the following technical solution:

[0007] In a first aspect, the present invention provides a space-time adaptive processing method for airborne broadband radar based on frequency domain compensation, comprising:

[0008] Acquire the target echo signal;

[0009] The broadband echo signal is sampled for distance to obtain the sampled target echo signal;

[0010] Perform a Fourier transform on the sampled target echo signal to obtain the target echo signal in the range frequency domain;

[0011] The target echo signal in the range frequency domain is subjected to matched filtering to obtain the matched filtered target echo signal.

[0012] According to the preset phase compensation factor, the envelope movement of the matched filtered target echo signal between each array element and each pulse is compensated to obtain the compensated target echo signal.

[0013] Perform an inverse Fourier transform on the compensated target echo signal to obtain the target echo signal in the range-time domain;

[0014] The echo signal in the distance-time domain is subjected to space-time adaptive processing to suppress clutter and noise.

[0015] The beneficial effects of this invention are:

[0016] This invention provides a space-time adaptive processing method for airborne broadband radar based on frequency domain compensation. By multiplying the matched-filtered frequency domain data by a phase compensation factor, the method accurately compensates for the distance migration of the target signal between array elements and between pulses, achieving envelope alignment of the target signal. Afterward, only one traditional STAP operation is required. In this way, the computational load can be reduced while improving broadband clutter suppression and target detection performance. Moreover, the improvement effect is more significant when the distance migration between array elements and between pulses is larger.

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 This is a flowchart of a space-time adaptive processing method for airborne broadband radar based on frequency domain compensation provided in an embodiment of the present invention;

[0019] Figure 2(a) is a schematic diagram of a narrowband EFA range Doppler output under the condition of the main beam pointing to the normal of the array surface provided by an embodiment of the present invention;

[0020] Figure 2(b) is a schematic diagram of the sub-band EFA range Doppler output under the condition of the main beam pointing to the array normal provided by an embodiment of the present invention;

[0021] Figure 2(c) is a schematic diagram of frequency domain compensation EFA range Doppler output under the condition of main beam pointing array normal provided by an embodiment of the present invention;

[0022] Figure 2(d) is a schematic diagram of an improvement factor curve under the condition of the main beam pointing array normal provided by an embodiment of the present invention;

[0023] Figure 3(a) is a schematic diagram of the narrowband EFA range Doppler output under main beam offset scanning conditions provided by an embodiment of the present invention;

[0024] Figure 3(b) is a schematic diagram of the sub-band EFA range Doppler output under main beam offset scanning conditions provided by an embodiment of the present invention;

[0025] Figure 3(c) is a schematic diagram of frequency domain compensation EFA range Doppler output under main beam offset sweep conditions provided by an embodiment of the present invention;

[0026] Figure 3(d) is a schematic diagram of an improvement factor curve under main beam offset scanning conditions provided by an embodiment of the present invention;

[0027] Figure 4(a) is a schematic diagram of the narrowband EFA distance Doppler output when the main beam offset angle increases, according to an embodiment of the present invention.

[0028] Figure 4(b) is a schematic diagram of the sub-band EFA distance Doppler output when the main beam offset angle increases, according to an embodiment of the present invention.

[0029] Figure 4(c) is a schematic diagram of frequency domain compensation for EFA distance Doppler output when the main beam offset angle increases, provided by an embodiment of the present invention.

[0030] Figure 4(d) is a schematic diagram of the improvement factor curve provided by an embodiment of the present invention when the main beam offset angle increases. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0032] Please see Figure 1 As shown, Figure 1 This is a flowchart of a space-time adaptive processing method for airborne broadband radar based on frequency domain compensation provided in an embodiment of the present invention. The space-time adaptive processing method for airborne broadband radar based on frequency domain compensation provided by the present invention includes:

[0033] S101, Obtain the target echo signal.

[0034] Specifically, in this embodiment, an airborne radar model is first constructed. The airborne radar model includes N linearly and uniformly arranged array elements, which are shared by the transmitting and receiving elements; wherein,

[0035] The expression for the linear frequency modulated signal u(t) transmitted by the transmitting element is:

[0036]

[0037] Where rect(·) is a rectangular window function, t is a fast time variable, and T p Where e is the pulse width, j is the natural base, and μ = B / T p Where B is the linear frequency modulation slope, and f is the signal bandwidth. c For carrier frequency, The initial phase is given by π, and π is the mathematical constant pi.

[0038] The broadband echo signal received by the receiving array element consists of three parts: the target echo signal, the clutter echo signal, and the noise signal. Specifically, the m-th pulse of the n-th array element receives the s-th target echo signal X. s,n,m The expression for (t) is:

[0039]

[0040]

[0041] Where, τ n,m R0 is the two-way delay of the m-th pulse signal returning to the n-th array element after being scattered by the target, d is the slant range between the reference element and the target when the reference pulse is emitted, ψ is the spatial cone angle of the target, and v is the distance between the array elements. r Let c be the relative velocity between the target and the carrier aircraft, and c be the speed of light.

[0042] S102. Perform distance sampling on the broadband echo signal to obtain the sampled target echo signal.

[0043] Specifically, in this embodiment, after range sampling, the target echo signal of the m-th pulse of the n-th array element after sampling in the l-th range unit is:

[0044]

[0045] Where T is the pulse repetition period.

[0046] The sampled target echo signal is represented as follows:

[0047]

[0048]

[0049] Among them, Xn,m L represents the L sampled data of the m-th pulse of the n-th array element, where L is the fast-time sampling number.

[0050] S103. Perform Fourier transform on the sampled target echo signal to obtain the target echo signal in the range frequency domain.

[0051] Specifically, in this embodiment, Fourier transform (FFT) is used to transform the sampled target echo signal to the range frequency domain to obtain the target echo signal in the range frequency domain. Its expression is:

[0052]

[0053]

[0054] Among them, f l The frequency of the l-th distance frequency point;

[0055] According to Fresnel integrals C(x) and S(x), when the bandwidth product is large, the target echo signal in the range frequency domain... To simplify, it can be made into:

[0056]

[0057]

[0058]

[0059] The expression for obtaining echo data in the distance-frequency domain is:

[0060]

[0061]

[0062] in, This represents the range-frequency domain data of the m-th pulse of the n-th array element.

[0063] S104. Perform matched filtering on the target echo signal in the range frequency domain to obtain the matched filtered target echo signal.

[0064] Specifically, in this embodiment, the frequency response of the matched filter is set as follows:

[0065]

[0066] Acquire the target echo signal after matched filtering Its expression is:

[0067]

[0068] S105. Based on the preset phase compensation factor, the envelope movement of the matched-filtered target echo signal between each array element and each pulse is compensated to obtain the compensated target echo signal.

[0069] Specifically, in this embodiment, based on the properties of the Fourier transform, it is known that the delay of a signal in the time domain corresponds to a phase shift in the frequency domain. Therefore, the matched-filtered target echo data is multiplied by a phase compensation factor to obtain the compensated target echo signal. Its expression is:

[0070]

[0071] in, For the compensated target echo signal, This is the preset phase compensation factor.

[0072] This embodiment can accurately compensate for the envelope movement of the target signal between each array element and each pulse.

[0073] S106. Perform an inverse Fourier transform on the compensated target echo signal to obtain the target echo signal in the range-time domain.

[0074] Specifically, in this embodiment, the inverse Fourier transform (IFFT) is used to transform the compensated target echo signal to the range-time domain, obtaining the range-time target echo signal Y. s ' ,n,m,l Its expression is:

[0075]

[0076] Where A is a constant and π is the value of pi;

[0077] According to the above formula, the target signal envelope center of each pulse of each array element is located at the 2R0L / cT+1 distance cell, which means that the target signal envelope alignment is achieved. At this time, the target signal model is a composite narrowband model, and the traditional space-time adaptive processing method (STAP) can be used for subsequent processing.

[0078] S107. Perform space-time adaptive processing on the target echo signal in the range-time domain to suppress clutter and noise.

[0079] Specifically, in this embodiment, in order to reduce the amount of computation and the requirement for training samples, the dimensionality reduction method of EFA is used, and the dimensionality reduction transformation matrix is ​​set to T. EFA Let Y' be an NM×3N dimensional matrix. The echo data after frequency domain compensation is denoted by Y'. Then the dimension-reduced echo data is:

[0080]

[0081] Where Y' represents the target echo data in the range time domain, and T EFA Let (·) be the dimension reduction transformation matrix. H Indicates conjugate transpose;

[0082] Based on the principle of maximizing the output signal-to-noise ratio, an optimization function is constructed, the expression of which is:

[0083]

[0084] Among them, R EFA S is the covariance matrix of clutter and noise after dimensionality reduction. s,t,EFA is the space-time steering vector of the reduced-dimensional target echo signal, and W is the weight vector of the space-time adaptive filter;

[0085] Among them, R EFA It can usually be estimated using training samples, that is:

[0086]

[0087] S s,t,EFA The expression is:

[0088]

[0089] Among them, S s and S t These are the spatial steering vector and temporal steering vector of the target echo signal before dimensionality reduction, respectively, and their expressions are as follows:

[0090]

[0091]

[0092] Solve the optimization function to obtain the optimal weight vector W. opt Its expression is:

[0093]

[0094]

[0095] in,(·) -1 This indicates finding the inverse;

[0096] Based on the optimal weight vector W opt The signal obtained by combining the dimension-reduced target echo signal Y” with the signal after suppressing clutter and noise is expressed as follows:

[0097]

[0098] It should be noted that the dimensionality reduction methods in step S106 are not limited to EFA, FA, and JDL.

[0099] It should be noted that the signals processed in the above embodiments are all broadband signals.

[0100] In summary, this invention provides a space-time adaptive processing method for airborne broadband radar based on frequency domain compensation. By multiplying the matched-filtered frequency domain data by a phase compensation factor, the distance migration of the target signal between array elements and between pulses is accurately compensated, achieving envelope alignment of the target signal. Afterward, only one traditional STAP operation is required. In this way, the computational load can be reduced while improving broadband clutter suppression and target detection performance. Moreover, the improvement effect is more significant when the distance migration between array elements and between pulses is larger.

[0101] In an optional embodiment of the present invention, the effectiveness of the method mentioned in the above embodiments is verified by simulation experiments. The traditional EFA processing method, the subband decomposition EFA processing method, and the processing method provided by the present invention are respectively set and compared. Then, the improvement of broadband clutter suppression and target detection performance of the present invention is analyzed by changing different array conditions.

[0102] In this simulation experiment, an airborne broadband phased array radar is used. The antenna array is a uniform linear array with 32 elements, the element spacing is 0.3m, the number of pulses in one coherent processing interval is 64, the pulse repetition frequency is 8000Hz, the signal carrier frequency is 500MHz, the bandwidth is 100MHz, and the flight speed of the carrier aircraft is 600m / s.

[0103] Please refer to Figures 2 to 4. Figure 2 is a schematic diagram of the simulation results of broadband clutter processing using the processing method of the present invention and the narrowband STAP and subband decomposition STAP methods under the condition of the main beam pointing plane normal. Figure 3 is a schematic diagram of the simulation results of broadband clutter processing using the processing method of the present invention and the narrowband STAP and subband decomposition STAP methods under the condition of the main beam offset. Figure 4 is a schematic diagram of the simulation results of broadband clutter processing using the processing method of the present invention and the narrowband STAP and subband decomposition STAP methods under the condition of the main beam offset angle increasing.

[0104] This embodiment presents simulation results of broadband clutter after space-time adaptive processing under different array conditions. Please refer to [link to simulation results]. Figures 2(a) to 2(d)As shown in the figures, Figure 2(a) is a schematic diagram of the narrowband EFA range Doppler output under the condition of the main beam pointing array normal provided by an embodiment of the present invention; Figure 2(b) is a schematic diagram of the sub-band EFA range Doppler output under the condition of the main beam pointing array normal provided by an embodiment of the present invention; Figure 2(c) is a schematic diagram of the frequency domain compensated EFA range Doppler output under the condition of the main beam pointing array normal provided by an embodiment of the present invention; and Figure 2(d) is a schematic diagram of the improvement factor curve under the condition of the main beam pointing array normal provided by an embodiment of the present invention. Under the condition of the main beam pointing array normal, no range travel will occur between the array elements. As can be seen from the figures, the performance of the three methods is very similar in the Doppler cells near the main lobe clutter. This is because the velocity corresponding to these Doppler cells is very small, and the inter-pulse range travel is small. However, due to the small velocity, it is difficult to distinguish the target from the clutter. The clutter suppression effect of the three methods is very poor in these Doppler cells, making target detection difficult. In Doppler cells far from the main lobe clutter, the performance of the frequency-domain compensated EFA method and the subband decomposition EFA method is very similar, both significantly better than the narrowband EFA method. Moreover, the closer to the outer Doppler cells, the better the improvement performance of both methods; the frequency focusing method can improve the improvement factor by up to 6.8 dB, and the subband decomposition method by up to 7 dB. This is because the velocity corresponding to the Doppler cells closer to the outer Doppler cells is greater, resulting in a larger distance travel between pulses. Using the narrowband EFA method for coherent accumulation reduces the target energy, while frequency-domain compensation eliminates the distance travel between pulses, and subband decomposition can ignore this distance travel. The target signal has higher energy after coherent accumulation, improving clutter correlation and resulting in better clutter suppression performance. It can be seen that the clutter suppression and target detection performance of the frequency-domain compensated method and the subband decomposition method are very similar; however, the subband decomposition method requires multiple STAPs, while the frequency-domain compensated method only needs to multiply by a phase compensation factor in the frequency domain and then perform one STAP, thus saving a significant amount of computation and better meeting the needs of real-time processing.

[0105] Please see Figures 3(a) to 3(d) As shown, Figure 3(a) is a schematic diagram of the narrowband EFA range-Doppler output under main beam offset conditions provided by an embodiment of the present invention; Figure 3(b) is a schematic diagram of the sub-band EFA range-Doppler output under main beam offset conditions provided by an embodiment of the present invention; Figure 3(c) is a schematic diagram of the frequency domain compensated EFA range-Doppler output under main beam offset conditions provided by an embodiment of the present invention; Figure 3(d) is a schematic diagram of the improvement factor curve under main beam offset conditions provided by an embodiment of the present invention. Due to the main beam offset, distance migration will occur between the array elements. Figures 2(a) to 2(d)In comparison, it can be seen that due to the distance travel between array elements, the frequency-domain compensation EFA method and the subband decomposition EFA method also show some performance improvement over the narrowband EFA method in Doppler cells near the main lobe clutter. In Doppler cells far from the main lobe clutter, the performance of the frequency-domain compensation EFA method and the subband decomposition EFA method is very close, both significantly better than the narrowband EFA method; moreover, the closer to the two Doppler cells, the better the improvement performance of both methods, with the frequency-domain compensation method improving the improvement factor by up to 8.8dB and the subband decomposition method by up to 9dB. This is because the velocity corresponding to the Doppler cells closer to the two sides is greater, resulting in a greater distance travel between pulses, and thus a greater total distance travel between array elements and between pulses. Using the narrowband EFA method for coherent accumulation reduces the target energy, while after frequency-domain compensation, there is no distance travel between array elements and between pulses, and after subband decomposition, the distance travel between array elements and between pulses can be ignored, resulting in higher energy of the target signal after coherent accumulation, improved clutter correlation, and better clutter suppression performance. It can be seen that the clutter suppression and target detection performance of the frequency domain compensation method is very close to that of the subband decomposition method, while saving a lot of computation, thus better meeting the needs of real-time processing. Figures 2(a) to 2(d) The comparison shows that when the main beam offset sweep leads to an increase in the total distance travel, frequency domain compensation and subband decomposition can achieve better performance improvement.

[0106] Please see Figures 4(a) to 4(d) As shown, Figure 4(a) is a schematic diagram of the narrowband EFA distance-Doppler output when the main beam deflection angle increases, provided by an embodiment of the present invention; Figure 4(b) is a schematic diagram of the sub-band EFA distance-Doppler output when the main beam deflection angle increases, provided by an embodiment of the present invention; Figure 4(c) is a schematic diagram of the frequency domain compensated EFA distance-Doppler output when the main beam deflection angle increases, provided by an embodiment of the present invention; and Figure 4(d) is a schematic diagram of the improvement factor curve when the main beam deflection angle increases, provided by an embodiment of the present invention. When the main beam deflection angle increases, the distance migration phenomenon between array elements will become more pronounced. Figures 3(a) to 3(d)In comparison, it can be seen that due to the increased distance travel between array elements, the frequency-domain compensation EFA method and the subband decomposition EFA method show greater performance improvements compared to the narrowband EFA method in Doppler cells near the main lobe clutter. In Doppler cells far from the main lobe clutter, the performance of the frequency-domain compensation EFA method and the subband decomposition EFA method is very similar, both significantly better than the narrowband EFA method. Moreover, the closer to the two Doppler cells, the better the improvement performance of both methods. The frequency-domain compensation method can improve the improvement factor by up to 10.7 dB, and the subband decomposition method by up to 11 dB. This is because the velocity corresponding to the Doppler cells closer to the two sides is greater, resulting in a larger distance travel between pulses. Consequently, the total distance travel between array elements and between pulses is also greater. Using the narrowband EFA method for coherent accumulation reduces the target energy, while after frequency-domain compensation, there is no distance travel between array elements and between pulses. After subband decomposition, the distance travel between array elements and between pulses can be ignored, resulting in higher energy of the target signal after coherent accumulation, improved clutter correlation, and better clutter suppression performance. It can be seen that the clutter suppression and target detection performance of the frequency domain compensation method is very close to that of the subband decomposition method, while saving a lot of computation, thus better meeting the needs of real-time processing. Comparing with Figures 3(a) to (d), it can be seen that when the main beam offset angle increases, leading to an increase in the total range travel, frequency domain compensation and subband decomposition can achieve better performance improvement.

[0107] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that an article or device comprising a list of elements includes not only those elements but also other elements not expressly listed. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device comprising said element. Terms such as "connected" or "linked" are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect. The orientations or positional relationships indicated by terms such as "upper," "lower," "left," and "right" are based on the orientations or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0108] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0109] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A space-time adaptive processing method for airborne broadband radar based on frequency domain compensation, characterized in that, include: Acquire the target echo signal; Range sampling is performed on the broadband echo signal to obtain the sampled target echo signal; Perform a Fourier transform on the sampled target echo signal to obtain the target echo signal in the range frequency domain; The target echo signal in the range frequency domain is subjected to matched filtering to obtain the matched filtered target echo signal. According to the preset phase compensation factor, the envelope movement of the matched filtered target echo signal between each array element and each pulse is compensated to obtain the compensated target echo signal. Perform an inverse Fourier transform on the compensated target echo signal to obtain the target echo signal in the range-time domain; The echo signal in the distance-time domain is subjected to space-time adaptive processing to suppress clutter and noise.

2. The space-time adaptive processing method for airborne broadband radar based on frequency domain compensation according to claim 1, characterized in that, Construct an airborne radar model, the airborne radar model including A linearly uniform array of elements, shared by the transmitting and receiving elements; among them, Linear frequency modulated signal transmitted by the transmitting element The expression is: ； in, For rectangular window functions, For fast time variables, The pulse width. The base is the natural number. The imaginary unit, For linear frequency modulation slope, For signal bandwidth, For carrier frequency, For the initial phase, Pi; The broadband echo signal received by the receiving array element includes the target echo signal, clutter echo signal, and noise signal, wherein the first Each formation element The target echo signal received by each pulse The expression is: ； ； in, For the first The pulse signal is scattered back to the target. Two-way delay of each array element, The slant range between the reference array element and the target when the reference pulse is emitted. For the spacing between array elements, The spatial cone angle of the target The relative speed between the target and the carrier aircraft. It is the speed of light.

3. The space-time adaptive processing method for airborne broadband radar based on frequency domain compensation according to claim 2, characterized in that, No. Each formation element The pulse at the ... The target echo signal after sampling for each range cell is: ； in, The pulse repetition period; The sampled target echo signal is represented as follows: ； ； in, For the first Each formation element pulse One sampled data, This refers to the number of samples taken in a fast time.

4. The space-time adaptive processing method for airborne broadband radar based on frequency domain compensation according to claim 3, characterized in that, The target echo signal in the range frequency domain The expression is: ； ； in, For the first The frequency of each distance frequency point; The expression for obtaining echo data in the distance-frequency domain is: ; ； in, For the first Each formation element Distance-frequency domain data of each pulse.

5. The space-time adaptive processing method for airborne broadband radar based on frequency domain compensation according to claim 4, characterized in that, The matched-filtered target echo signal The expression is: ； in, This represents the frequency response of the matched filter.

6. The space-time adaptive processing method for airborne broadband radar based on frequency domain compensation according to claim 5, characterized in that, The step of compensating for the envelope movement of the matched-filtered target echo signal between each array element and each pulse according to a preset phase compensation factor to obtain the compensated target echo signal includes: The preset phase compensation factor is multiplied by the matched-filtered target echo signal to obtain the compensated target echo signal. Its expression is: ； in, For the compensated target echo signal, This is the preset phase compensation factor.

7. The space-time adaptive processing method for airborne broadband radar based on frequency domain compensation according to claim 6, characterized in that, The target echo signal in the distance-time domain The expression is: ； in, It is a constant. Pi is the mathematical constant of a circle.

8. The space-time adaptive processing method for airborne broadband radar based on frequency domain compensation according to claim 1, characterized in that, The step of performing spatiotemporal adaptive processing on the target echo signal in the range-time domain includes: The target echo signal in the range-time domain is reduced in dimension to obtain the reduced target echo signal. Its expression is: ； in, For target echo data in the distance-time domain, This is the dimension reduction transformation matrix. It is the conjugate transpose; Based on the principle of maximizing the output signal-to-noise ratio, an optimization function is constructed, the expression of which is: ； in, The covariance matrix of clutter and noise after dimensionality reduction. The space-time steering vector of the reduced-dimensional target echo signal. The weight vector for adaptive filtering when empty; Solve the optimization function to obtain the optimal weight vector. Its expression is: ； ； in, This indicates finding the inverse; Based on the optimal weight vector and the target echo signal after dimensionality reduction The signal obtained after suppressing clutter and noise is expressed as follows: 。

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