Deception jamming method and deception jamming device for azimuth phase coding SAR (Synthetic Aperture Radar)

Abstract

The invention discloses a deception jamming method and device for an azimuth phase coding SAR (synthetic aperture radar), and belongs to the technical field of electronic support system synthetic aperture radar countermeasure. The method comprises the following steps: intercepting an SAR signal, carrying out two-dimensional structured phase stripping by constructing an inverse distance modulation operator and an inverse azimuth modulation operator, and estimating to obtain an azimuth phase sequence; carrying out complex domain differential operation on the estimated azimuth phase sequence, constructing a phase consistency measurement index and minimum consistency order mapping, and identifying a coding structure of the phase consistency measurement index and the minimum consistency order mapping; constructing a linear least square problem based on an identification result, and reconstructing an azimuth phase sequence; and performing phase consistent modulation including convolution modulation on the intercepted signal to generate a deception jamming signal. According to the method, complete matching of the interference signal and the SAR receiving filter is realized, and effective deception interference can be implemented on a new system SAR adopting random, primary, secondary and grouped phase coding.

Description

Technical Field

[0001] This invention belongs to the field of Electronic Support Measures (ESM) Synthetic Aperture Radar (SAR) countermeasures technology, specifically relating to a deception jamming method and apparatus for azimuth phase-coded SAR. Background Technology

[0002] Synthetic Aperture Radar (SAR) is an active microwave imaging system with all-weather, all-day, high-resolution ground imaging capabilities, playing an irreplaceable role in military reconnaissance and civilian surveying. To protect important targets from SAR reconnaissance threats, effective jamming of SAR has become a research hotspot in the field of electronic warfare. Among these methods, deception jamming, due to its ability to intercept and forward signals highly similar to real echoes in real time, can generate designated false targets in SAR images. It boasts advantages such as low jamming power, high concealment, and realistic effects, making it an important development direction for SAR countermeasures technology.

[0003] Existing deception jamming techniques, such as the "A Method for Generating Spaceborne SAR Deception Jamming Signals Based on Spatial Frequency Interpolation" proposed in Chinese Patent Application No. CN202011240836.0, mainly focus on improving the generation speed of jamming templates to achieve large-scale scene deception; while the "A Method and System for Deception Jamming SAR Sea Surface Scenes" proposed in Chinese Patent Publication No. CN112180345A emphasizes incorporating dynamic sea surface information into the jamming template to improve simulation accuracy. However, the above studies are all based on traditional SAR signal models, and their jamming targets implicitly assume that the SAR system transmitting conventional linear frequency modulated signals is the target of the jamming.

[0004] With the development of SAR technology, new anti-jamming waveforms are constantly emerging. Azimuth phase-coded SAR is a typical new anti-jamming system. It adds an inter-pulse agile initial phase (including random phase coding, primary phase coding, secondary phase coding, and group phase coding) to the transmitted signal in the azimuth direction, causing a severe mismatch between the jamming signal lagging behind the true echo and the phase-agile matched filter at the receiver, thereby effectively suppressing repeater-based deception interference. This technology has become an important development direction in the field of SAR anti-jamming.

[0005] However, existing deception jamming techniques did not consider the special characteristics of azimuth phase coding in their initial design. When using traditional methods to jam azimuth phase-coded SAR, the jamming signal cannot possess the same azimuth phase agility as the real echo, resulting in its energy not being effectively focused after matched filtering, thus severely suppressing or even completely eliminating the jamming effect. Currently, research on how to overcome the anti-jamming barriers of azimuth phase-coded SAR and achieve effective deception jamming is still lacking.

[0006] In summary, there is an urgent need for a deception jamming method that can sense and match the azimuth phase coding structure to solve the problem that existing technologies lack jamming effectiveness against azimuth phase-coded SAR and fill the technological gap in this field. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a deception jamming method and apparatus for azimuth phase-coded SAR. By sensing, identifying, and reconstructing the azimuth inter-pulse phase coding structure of the target SAR, the generated deception jamming signal possesses phase agility characteristics that perfectly match the target SAR, thereby breaking through the anti-jamming barrier of azimuth phase-coded SAR.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A deception jamming method for azimuth phase-coded SAR, the method comprising:

[0010] Step 1: Construct the inverse range modulation operator and the inverse azimuth modulation operator, and perform two-dimensional structured phase stripping on the intercepted SAR signal to obtain the estimated azimuth phase sequence;

[0011] Step 2: Perform complex domain differencing on the estimated azimuth phase sequence to construct a phase consistency metric and a minimum consistency order mapping, and identify the encoding structure of the estimated azimuth phase sequence:

[0012] Step 3: Based on the recognition results of the coding structure, construct a linear least squares problem to characterize the reconstruction of the coding structure, and obtain the reconstructed azimuth phase sequence;

[0013] Step 4: Based on the estimated or reconstructed azimuth phase sequence, perform phase-consistent modulation on the intercepted SAR signal to generate a deception jamming signal and forward it.

[0014] Furthermore, step 1 includes: constructing an inverse range modulation operator based on the frequency modulation slope and carrier frequency parameters of the intercepted SAR signal, performing inverse range modulation on the intercepted SAR signal to remove the range-direction linear frequency modulation phase; constructing an inverse azimuth modulation operator based on the estimated SAR Doppler modulation frequency and zero Doppler time, performing inverse azimuth modulation on the SAR signal after inverse range modulation to remove the azimuth-direction secondary modulation phase; extracting the main phase pulse by pulse along the azimuth direction from the SAR signal after removing the azimuth-direction secondary modulation phase to obtain the estimated azimuth phase sequence.

[0015] Further, step 2 includes: converting the estimated azimuth phase sequence into a complex domain representation, and obtaining its first-order and second-order complex domain difference sequences; constructing a phase consistency metric based on the complex domain difference results, wherein the phase consistency metric is used to determine the consistency order of the phase between adjacent pulses; constructing a minimum consistency order mapping, and aggregating pulse indices into different index sets according to the consistency order; and identifying the encoding structure of the azimuth phase sequence as one of random phase encoding, single-phase encoding, double-phase encoding, or grouped phase encoding based on the allocation of the index sets.

[0016] Furthermore, the grouped phase coding is composed of polynomial phase coding on multiple disjoint index sets. When multiple index sets are assigned and each set has the same consistency order, it is identified as grouped phase coding; when only one index set is assigned, it is identified as a single phase coding type corresponding to that set.

[0017] Furthermore, step 3 includes: constructing the initial coding index and coding coefficients into equivalent polynomial coefficients based on the identified coding type and index set allocation results; characterizing the coding structure reconstruction problem as a linear least squares problem, where the variable to be solved is the equivalent polynomial coefficient matrix; obtaining the optimal solution of the equivalent polynomial coefficients by solving the linear least squares problem, and then reconstructing the azimuth phase sequence consistent with the azimuth phase coding structure of the SAR transmitted signal.

[0018] Furthermore, step 4 includes: performing convolutional deception modulation on the intercepted SAR signal to generate a preliminary interference signal; determining the number of pulses by which the preliminary interference signal lags behind the real echo; and performing phase-consistent modulation on the preliminary interference signal according to the identified coding type and the reconstructed azimuth phase sequence, so that the generated deception interference signal has the same azimuth inter-pulse phase agility characteristics as the SAR transmitted signal.

[0019] Furthermore, the phase-consistent modulation includes two modes: when the identified coding type is random phase coding or randomized grouped phase coding, the azimuth phase sequence estimated in step 1 is used for phase-consistent real-time modulation; when the identified coding type is primary phase coding, secondary phase coding or non-randomized grouped phase coding, the azimuth phase sequence reconstructed in step 3 is used for phase-consistent predictive modulation.

[0020] On the other hand, the present invention provides a deception jamming device for azimuth phase-coded SAR, comprising:

[0021] The estimation module is used to construct the inverse range modulation operator and the inverse azimuth modulation operator, and to perform two-dimensional structured phase stripping on the intercepted SAR signal to obtain the estimated azimuth phase sequence.

[0022] The identification module performs complex-domain differencing on the estimated azimuth phase sequence and identifies the encoding structure of the estimated azimuth phase sequence through a phase consistency metric and a minimum consistency order mapping.

[0023] The reconstruction module is used to construct a linear least squares problem representing the reconstruction of the coding structure based on the recognition result of the coding structure, and obtain the reconstructed azimuth phase sequence.

[0024] The generation module is used to perform phase-consistent modulation on the intercepted SAR signal based on the reconstructed azimuth phase sequence, generate a deception jamming signal, and forward it.

[0025] Thirdly, the present invention provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned deception jamming method for azimuth phase-coded SAR.

[0026] Fourthly, the present invention provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, enable the processor to implement the aforementioned deception jamming method for azimuth phase-coded SAR.

[0027] The beneficial effects of this invention are as follows:

[0028] First, this invention fills a gap in deception jamming technology for azimuth phase-coded SAR. Existing deception jamming methods are all based on traditional SAR signal models and cannot adapt to the new anti-jamming system with azimuth phase agility between pulses. This invention, by constructing a novel processing framework of "azimuth phase estimation - coding structure identification - coding structure reconstruction - phase-consistent modulation," achieves for the first time effective deception jamming against four types of azimuth phase-coded SAR using random, primary, secondary, and grouped phase coding, solving the problem of severe mismatch between the jamming signal and the SAR receiving filter leading to jamming failure.

[0029] Second, it possesses intelligent perception and adaptive jamming capabilities for unknown coding structures. The coding structure identification algorithm proposed in this invention can automatically determine the specific coding type used by the opposing SAR through complex domain differential operations and minimum consistency order mapping. Based on the identification results, it generates matching jamming signals using phase-consistent real-time modulation or phase-consistent predictive modulation, enabling the jammer to possess the versatility and adaptability to counter various unknown waveform agile SARs.

[0030] Third, the jamming effect is good, and the focusing accuracy of false targets is high. Since the reconstructed azimuth and phase sequence is almost completely consistent with the phase coding of the real echo, the jamming signal can obtain the same matching processing gain as the real target. The generated false targets are well focused and accurately positioned, and are highly integrated with the real targets in the SAR image, making them difficult to distinguish. This significantly improves the realism and concealment of the deception jamming. Attached Figure Description

[0031] Figure 1 This is a flowchart of a deception jamming method for azimuth phase-coded SAR according to the present invention;

[0032] Figure 2 A schematic diagram of the geometric model for deceiving and jamming directional phase-coded SAR provided by the present invention;

[0033] Figure 3 A schematic diagram of the raw echo imaging results of azimuth phase-coded SAR;

[0034] Figure 4 This is a schematic diagram of the imaging results obtained after applying the method of the present invention to azimuth phase-coded SAR for deception jamming. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0036] like Figure 1As shown, this embodiment of the invention provides a deception jamming method for azimuth phase-coded SAR. It employs a process of "azimuth phase estimation - coding structure identification - coding structure reconstruction - phase-consistent modulation" to address the mismatch between the jamming signal and the SAR filter, achieving effective deception jamming of azimuth phase-coded SAR. Specifically, it includes the following steps:

[0037] Step 1: Intercept the SAR signal, construct the inverse range modulation operator and the inverse azimuth modulation operator, and perform two-dimensional structured phase stripping on the intercepted SAR signal to obtain the estimated azimuth phase sequence;

[0038] Step 2: Perform complex domain differencing on the estimated azimuth phase sequence, and identify the coding structure of the azimuth phase sequence by constructing a phase consistency metric and a minimum consistency order mapping:

[0039] Step 3: Based on the recognition results of the coding structure, construct a linear least squares problem to characterize the reconstruction of the coding structure, and obtain the reconstructed azimuth phase sequence;

[0040] Step 4: Based on the estimated or reconstructed azimuth phase sequence, perform phase-consistent modulation (including convolutional modulation) on the intercepted SAR signal to generate a deception jamming signal and forward it.

[0041] Specifically, step 1 includes:

[0042] Step 1.1: Intercept the SAR sidelobe signal and obtain its basic parameters.

[0043] Construction as Figure 2 The diagram shows a geometric model for deceiving and jamming SAR systems. A flight platform A carrying the SAR system flies at a speed v along the X-axis at an altitude h. The initial position of platform A projected onto the ground is denoted as the origin O. The jammer is located at point J. The false target generated by the jammer is located at point F. R represents the distance from any target in the imaging scene to A.

[0044] The signal intercepted by the jammer is represented as follows:

[0045] (1)

[0046] in, and These represent time in the distance direction and time in the direction of orientation, respectively; c represents the speed of light; and j represents the imaginary unit. Represents the distance envelope function. Represents the azimuth envelope function. Indicates zero Doppler time. Indicates the carrier frequency. Indicates the frequency modulation slope. This represents the instantaneous slant distance from jammer J to flight platform A. The azimuth phase coding includes four coding structures: random phase coding, primary phase coding, secondary phase coding, and group phase coding. Their unified mathematical model is as follows:

[0047] (2)

[0048] The encoding structure consists of encoding index m and index set. and coding coefficients Together they form a single component. Among them, m increases sequentially with the number of azimuth pulses. The sets of values ​​S for m are disjoint and together form a set of values ​​for m. i represents the polynomial order of the phase code corresponding to the index set and coding coefficients, with orders of 0, 1, and 2. Random phases are considered to be of order 0. express Independent random variables uniformly distributed within an interval. This model is essentially a piecewise polynomial phase model, where different polynomial orders are activated on disjoint sets of indices.

[0049] Intercepted signal It contains three deterministic phase components: azimuth phase encoding, azimuth secondary modulation phase, and range linear frequency modulation phase. Basic parameter estimation of this signal yields... and The specific values ​​of parameters such as...

[0050] Step 1.2: Construct an inverse range modulation operator to perform inverse range modulation on the intercepted signal.

[0051] Based on the intercepted signals Based on the parameter estimation results, the inverse range modulation operator is constructed as follows:

[0052] (3)

[0053] Among them, the transmission time Use this function to intercept signals By performing inverse distance modulation to strip the linear frequency modulation phase, we obtain:

[0054] (4)

[0055] Step 1.3: Construct an inverse azimuth modulation operator to perform inverse azimuth modulation on the intercepted signal.

[0056] The inverse azimuth modulation operator is constructed as follows:

[0057] (5)

[0058] in, This represents the intercepted signal window used for initial phase estimation. Part of it. It is the estimated SAR zero Doppler time. This is the estimated SAR Doppler modulation frequency. Using this function to perform inverse azimuth modulation on the intercepted signal to remove the azimuth secondary modulation phase, we obtain:

[0059] (6)

[0060] The second exponential term is the zero Doppler slant range of the jammer. The corresponding constant phase. The above formula omits residual phase errors that do not affect subsequent processing.

[0061] Step 1.4: Solve for the signal phase to obtain the estimated azimuth phase sequence.

[0062] The main phase is extracted pulse-by-pulse along the azimuth direction from the signal after stripping the linear frequency modulation phase and the azimuth secondary modulation phase. The estimated azimuth phase sequence is obtained. T represents transpose. M is the number of pulses intercepted.

[0063] Step 2: Perform complex domain difference operations on the estimated azimuth phase sequence, and identify the coding structure of the azimuth phase sequence by constructing a phase consistency metric and a minimum consistency order mapping.

[0064] Step 2.1: Represent the estimated azimuth initial phase sequence in the complex field and obtain its complex field difference sequence.

[0065] The complex field representation of the estimated azimuth initial phase sequence is as follows:

[0066] (7)

[0067] The formula for solving the difference sequence in the first-order complex field is:

[0068] (8)

[0069] The formula for solving the difference sequence in the higher-order complex field is:

[0070] (9)

[0071] in, Indicates the difference order. This represents the conjugate operation. The highest order is 2, therefore complex field differences need to be calculated to the second order.

[0072] Step 2.2: Construct a phase consistency metric to determine the phase characteristics of the sequence.

[0073] The polynomial properties of the azimuth phase coding structure determine that, for those belonging to the index set If the encoded index m is an i-th order polynomial, then its (i+1)-th order complex difference will converge to 1. Based on this property, a phase consistency metric is constructed:

[0074] (10)

[0075] The smaller this index is, the stronger the k-th order polynomial phase consistency of the phase codes corresponding to indices m and m+1.

[0076] Step 2.3: Construct a minimum consistency order mapping to identify the coding structure of the azimuth phase sequence.

[0077] Construct a minimum consistency order mapping:

[0078] (11)

[0079] in, This represents the consistency threshold. For indices that do not have a minimum consistency order, they are aggregated to obtain a set of indices with a random phase structure. ; for those with the same The consecutive indices are aggregated to obtain the index set of each polynomial phase structure:

[0080] (12)

[0081] This determined the index set in the initial phase encoding structure. .

[0082] The encoding structure of the azimuth phase sequence is identified based on the allocation of index sets: when only one set is assigned an index, and the other two are empty sets, the encoding structure is a single-phase code corresponding to the unique non-empty set. When multiple sets are assigned indexes, the model represents a grouped phase code. Thus, four types of azimuth phase encoding structures were identified: random phase, primary phase, secondary phase, and grouped phase.

[0083] Step 3: Based on the coding structure recognition results, construct a linear least squares problem to represent the reconstruction of the coding structure, and obtain the reconstructed azimuth phase sequence.

[0084] Step 3.1: Construct the coding structure reconstruction problem based on the coding structure recognition results.

[0085] The encoded structure recognition result includes an index set. To reconstruct the coding structure, it is also necessary to solve for the coding index m and coding coefficients. .in The relative value of index m is already included; the initial index still needs to be solved. .

[0086] Initial index Incorporating coding coefficients In the middle, the estimated azimuth phase It can be represented as:

[0087] (13)

[0088] in, This represents the residual constant phase included in the azimuth phase estimation result. Expanding the above equation using the binomial theorem:

[0089] (14)

[0090] Therefore, the problem of reconstructing the coding structure only requires solving the following... and Equivalent polynomial coefficients constructed jointly .

[0091] Step 3.2: Represent the coding structure reconstruction problem as a linear least squares problem and solve it to obtain the reconstructed azimuth phase sequence.

[0092] Will The corresponding phase samples are extracted from the estimated phase sequence as a subset of the estimated phase. The coding structure reconstruction problem can then be characterized as a linear least squares problem:

[0093] (15)

[0094] in, It is the equivalent polynomial coefficient matrix, defined as , It is by The Vandermonde matrix is ​​constructed from the encoded indexes in the matrix. It is full rank, therefore The optimal solution exists in the following closed-form expression:

[0095] (16)

[0096] Here, H represents the conjugate transpose operation on the matrix.

[0097] Thus, all the unknowns contained in the encoding structure have been solved. For each existing subset of phases... By solving each step individually, the complete reconstructed azimuth phase sequence can be obtained:

[0098] (17)

[0099] Step 4: Perform phase-consistent modulation, including convolution modulation, on the intercepted signal to generate a deception interference signal.

[0100] Step 4.1: Perform convolutional deception modulation on the intercepted signal.

[0101] The intercepted signal is modulated based on the modulation principle of convolutional deception interference to obtain a convolutional interference signal:

[0102] (18)

[0103] in, Let F be the distance history difference between the desired false target F and the jammer J relative to the flight platform A, which is also the distance history that the jammer needs to modulate. The backscattering coefficient of the dummy target. This represents the impact response function.

[0104] Step 4.2: Perform phase-consistent modulation based on the time lag between the interference signal and the actual echo.

[0105] Based on the convolution modulation of the jammer and the pulse repetition period of SAR, the number of pulses n that the jamming signal lags behind the real echo is determined.

[0106] Phase-coherent modulation is performed on the convolutionally modulated signal based on the number of pulses n. Depending on the phase coding structure, phase-coherent modulation includes two types.

[0107] For random phase coding or grouped phase coding with randomness, the estimated azimuth phase sequence is used. Phase-consistent modulation is performed to obtain a phase-consistent convolutional interference signal:

[0108] (19)

[0109] This modulation process is called phase-consistent real-time modulation because the phase used for modulation is estimated in real time after each interception of the SAR signal.

[0110] For primary phase coding, secondary phase coding, and non-random grouped phase coding, reconstructed azimuth phase sequences are used. Phase-consistent modulation is performed to obtain a phase-consistent convolutional interference signal:

[0111] (20)

[0112] This modulation approach is called phase-consistent predictive modulation (PCM) because the phase used for modulation is pre-calculated based on the reconstructed coding structure. The advantage of PCM is that the transmission time of the jamming signal is not limited by the interception time, allowing for more flexible positioning of false targets.

[0113] The phase-coherently modulated interference signal is the final generated deception jamming signal. Transmitting this signal to the azimuth phase-coded SAR can effectively deceive and jam it.

[0114] Example:

[0115] The operating parameters of a typical high-resolution SAR on a high-altitude long-endurance UAV in strip mode are shown in Table 1. A deception jamming experiment was conducted using real SAR images acquired by the Gaofen-3 satellite. The imaging results before jamming are shown below. Figure 3 As shown in the diagram. J represents the location of the jammer, and the port within the box represents the actual target pattern used to generate the deceptive jamming signal.

[0116] Table 1

[0117]

[0118] The experiment targeted azimuth-grouped phase-coded SAR, and the deception jamming method proposed in this embodiment of the invention was used to perform deception jamming. The jamming results are as follows: Figure 4 As shown, a fake port appeared on the originally empty water surface within the box, and it was so similar to a real port that it was difficult to distinguish, thus achieving a good deception and camouflage effect. Therefore, the effectiveness of this embodiment of the invention is verified.

[0119] On the other hand, embodiments of the present invention provide a deception jamming device for azimuth phase-coded SAR, which includes modules capable of implementing the steps of the aforementioned method, specifically including:

[0120] The estimation module is used to construct the inverse range modulation operator and the inverse azimuth modulation operator, and to perform two-dimensional structured phase stripping on the intercepted SAR signal to obtain the estimated azimuth phase sequence.

[0121] The identification module performs complex-domain differencing on the estimated azimuth phase sequence and identifies the encoding structure of the estimated azimuth phase sequence through a phase consistency metric and a minimum consistency order mapping.

[0122] The reconstruction module is used to construct a linear least squares problem representing the reconstruction of the coding structure based on the recognition result of the coding structure, and obtain the reconstructed azimuth phase sequence.

[0123] The generation module is used to perform phase-consistent modulation on the intercepted SAR signal based on the reconstructed azimuth phase sequence, generate a deception jamming signal, and forward it.

[0124] Thirdly, embodiments of the present invention provide an electronic device, including: one or more processors; a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned deception jamming method for azimuth phase-coded SAR.

[0125] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing executable instructions thereon, which, when executed by a processor, enable the processor to implement the aforementioned deception jamming method for azimuth phase-coded SAR.

[0126] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A deception jamming method for azimuth phase-coded SAR, characterized in that, The method includes: Step 1: Construct the inverse range modulation operator and the inverse azimuth modulation operator, and perform two-dimensional structured phase stripping on the intercepted SAR signal to obtain the estimated azimuth phase sequence; Step 2: Perform complex domain differencing on the estimated azimuth phase sequence to construct a phase consistency metric and a minimum consistency order mapping, and identify the encoding structure of the estimated azimuth phase sequence: Step 3: Based on the recognition results of the coding structure, construct a linear least squares problem to characterize the reconstruction of the coding structure, and obtain the reconstructed azimuth phase sequence; Step 4: Based on the estimated or reconstructed azimuth phase sequence, perform phase-consistent modulation on the intercepted SAR signal to generate a deception jamming signal and forward it.

2. The deception jamming method for azimuth phase-coded SAR according to claim 1, characterized in that, Step 1 includes: constructing an inverse range modulation operator based on the frequency modulation slope and carrier frequency parameters of the intercepted SAR signal, performing inverse range modulation on the intercepted SAR signal to remove the range-direction linear frequency modulation phase; constructing an inverse azimuth modulation operator based on the estimated SAR Doppler modulation frequency and zero Doppler time, performing inverse azimuth modulation on the SAR signal after inverse range modulation to remove the azimuth-direction secondary modulation phase; extracting the main phase pulse by pulse along the azimuth direction from the SAR signal after removing the azimuth-direction secondary modulation phase to obtain the estimated azimuth phase sequence.

3. The deception jamming method for azimuth phase-coded SAR according to claim 1, characterized in that, Step 2 includes: converting the estimated azimuth phase sequence into a complex domain representation, and obtaining its first-order and second-order difference sequences in the complex domain; constructing a phase consistency metric based on the complex domain difference results, wherein the phase consistency metric is used to determine the consistency order of the phase between adjacent pulses; constructing a minimum consistency order mapping, and aggregating pulse indices into different index sets according to the consistency order; and identifying the encoding structure of the azimuth phase sequence as one of random phase encoding, single-phase encoding, double-phase encoding, or grouped phase encoding based on the allocation of the index sets.

4. The deception jamming method for azimuth phase-coded SAR according to claim 3, characterized in that, The grouped phase coding is composed of polynomial phase coding on multiple disjoint index sets. When multiple index sets are assigned and each set has the same consistency order, it is identified as grouped phase coding; when only one index set is assigned, it is identified as the single phase coding type corresponding to that set.

5. The deception jamming method for azimuth phase-coded SAR according to claim 1, characterized in that, Step 3 includes: constructing the initial coding index and coding coefficients into equivalent polynomial coefficients based on the identified coding type and index set allocation results; characterizing the coding structure reconstruction problem as a linear least squares problem, where the variable to be solved is the equivalent polynomial coefficient matrix; obtaining the optimal solution of the equivalent polynomial coefficients by solving the linear least squares problem, and then reconstructing the azimuth phase sequence consistent with the azimuth phase coding structure of the SAR transmitted signal.

6. The deception jamming method for azimuth phase-coded SAR according to claim 1, characterized in that, Step 4 includes: performing convolutional deception modulation on the intercepted SAR signal to generate a preliminary interference signal; determining the number of pulses that the preliminary interference signal lags behind the real echo; and performing phase-consistent modulation on the preliminary interference signal according to the identified coding type and the reconstructed azimuth phase sequence, so that the generated deception interference signal has the same azimuth inter-pulse phase agility characteristics as the SAR transmitted signal.

7. A deception jamming method for azimuth phase-coded SAR according to claim 6, characterized in that, The phase-consistent modulation includes two modes: when the identified coding type is random phase coding or randomized grouped phase coding, the azimuth phase sequence estimated in step 1 is used for phase-consistent real-time modulation; when the identified coding type is primary phase coding, secondary phase coding or non-randomized grouped phase coding, the azimuth phase sequence reconstructed in step 3 is used for phase-consistent predictive modulation.

8. A deception jamming device for azimuth phase-coded SAR, characterized in that, include: The estimation module is used to construct the inverse range modulation operator and the inverse azimuth modulation operator, and to perform two-dimensional structured phase stripping on the intercepted SAR signal to obtain the estimated azimuth phase sequence. The identification module performs complex-domain differencing on the estimated azimuth phase sequence and identifies the encoding structure of the estimated azimuth phase sequence through a phase consistency metric and a minimum consistency order mapping. The reconstruction module is used to construct a linear least squares problem representing the reconstruction of the coding structure based on the recognition result of the coding structure, and obtain the reconstructed azimuth phase sequence. The generation module is used to perform phase-consistent modulation on the intercepted SAR signal based on the reconstructed azimuth phase sequence, generate a deception jamming signal, and forward it.

9. An electronic device, characterized in that, include: One or more processors; Memory, used to store one or more programs; When one or more programs are executed by the one or more processors, the one or more processors implement the deception jamming method for azimuth phase-coded SAR as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, It stores executable instructions that, when executed by a processor, enable the processor to implement a deception jamming method for azimuth phase-coded SAR as described in any one of claims 1-7.

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