CN-121978636-A - Spoofing interference method and device for azimuth phase coding SAR

CN121978636ACN 121978636 ACN121978636 ACN 121978636ACN-121978636-A

Abstract

The invention discloses a deception jamming method and device aiming at azimuth phase coding SAR, and belongs to the technical field of synthetic aperture radar countermeasure of electronic support systems. The method comprises the steps of intercepting SAR signals, carrying out two-dimensional structured phase stripping through constructing an inverse distance modulation operator and an inverse azimuth modulation operator, estimating to obtain azimuth phase sequences, carrying out complex domain difference operation on the estimated azimuth phase sequences, constructing a phase consistency measurement index and a minimum consistency order mapping, identifying a coding structure of the estimated azimuth phase sequences, constructing a linear least square problem based on an identification result, reconstructing the azimuth phase sequences, and carrying out phase consistency modulation comprising convolution modulation on the intercepted signals to generate deceptive interference signals. The invention realizes the complete matching of the interference signal and the SAR receiving filter, and can effectively deception jamming on the novel system SAR adopting random, primary, secondary and block phase coding.

Inventors

LU WEI
ZHANG JIALE
Hou Jinshuo
WU YINGYING
JI YICAI
LIU XIAOJUN
FANG GUANGYOU

Assignees

中国科学院空天信息创新研究院

Dates

Publication Date: 20260505
Application Date: 20260401

Claims (10)

1. A method of spoofing an azimuthal phase encoded SAR, the method comprising: step 1, constructing an inverse distance modulation operator and an inverse azimuth modulation operator, and performing two-dimensional structured phase stripping on intercepted SAR signals to obtain an estimated azimuth phase sequence; Step 2, performing complex domain differential operation on the estimated azimuth phase sequence, constructing a phase consistency measurement index and a minimum consistency order mapping, and identifying the coding structure of the estimated azimuth phase sequence: Step 3, constructing a linear least square problem for representing the reconstruction of the coding structure based on the coding structure identification result to obtain a reconstructed azimuth phase sequence; and 4, according to the estimated or reconstructed azimuth phase sequence, performing phase consistent modulation on the intercepted SAR signal, generating a deception jamming signal and forwarding the deception jamming signal.
2. The method for cheating interference of azimuth phase coded SAR according to claim 1, wherein the step 1 comprises constructing an inverse distance modulation operator according to frequency modulation slope and carrier frequency parameters of an intercepted SAR signal, performing inverse distance modulation on the intercepted SAR signal to strip a distance-wise linear frequency modulation phase, constructing an inverse azimuth modulation operator according to estimated SAR Doppler frequency and zero Doppler time, performing inverse azimuth modulation on the SAR signal subjected to inverse distance modulation to strip an azimuth secondary modulation phase, and extracting a main phase of the SAR signal subjected to azimuth secondary modulation phase along azimuth pulse by pulse to obtain an estimated azimuth phase sequence.
3. The method for spoofing and jamming for azimuth phase coding SAR according to claim 1, wherein the step 2 comprises the steps of converting an estimated azimuth phase sequence into a complex domain representation and solving a complex domain first-order differential sequence and a complex domain second-order differential sequence thereof, constructing a phase consistency metric index according to a complex domain differential result, wherein the phase consistency metric index is used for judging the consistency order of phases between adjacent pulses, constructing a minimum consistency order mapping, aggregating pulse indexes into different index sets according to the consistency order, and identifying the coding structure of the azimuth phase sequence as one of random phase coding, primary phase coding, secondary phase coding or grouping phase coding according to the distribution condition of the index sets.
4. The method of claim 3, wherein the block phase code is composed of a combination of polynomial phase codes over a plurality of disjoint sets of indices, and is identified as a block phase code when the sets of indices are assigned and each set has the same order of consistency, and is identified as a single phase code type for one set of indices when only one set of indices is assigned.
5. The method for spoofing and jamming for azimuth phase coded SAR according to claim 1, wherein the step 3 comprises constructing an initial coding index and a coding coefficient as equivalent polynomial coefficients according to the identified coding type and index set allocation result, characterizing a coding structure reconstruction problem as a linear least square problem, wherein variables to be solved are equivalent polynomial coefficient matrixes, obtaining an optimal solution of the equivalent polynomial coefficients by solving the linear least square problem, and reconstructing an azimuth phase sequence consistent with an azimuth phase coding structure of an SAR transmitting signal.
6. The method for spoofing interference against azimuth phase coded SAR according to claim 1, wherein the step 4 comprises performing convolution spoofing modulation on the intercepted SAR signal to generate a preliminary interference signal, determining the pulse number of a real echo behind the preliminary interference signal, and performing phase consistent modulation on the preliminary interference signal according to the identified coding type and the reconstructed azimuth phase sequence to enable the generated spoofing interference signal to have the same azimuth inter-pulse phase agility characteristic as the SAR transmission signal.
7. The method of claim 6, wherein the phase-consistent modulation includes two modes, namely, performing phase-consistent real-time modulation by using the azimuth phase sequence estimated in the step 1 when the identified code type is random phase code or random block phase code, and performing phase-consistent predictive modulation by using the azimuth phase sequence reconstructed in the step 3 when the identified code type is primary phase code, secondary phase code or non-random block phase code.
8. A spoofing jamming device for azimuth phase encoded SAR, comprising: the estimation module is used for constructing an inverse distance modulation operator and an inverse azimuth modulation operator, and performing two-dimensional structured phase stripping on the intercepted SAR signals to obtain an estimated azimuth phase sequence; The identification module is used for carrying out complex domain differential operation on the estimated azimuth phase sequence, and identifying the coding structure of the estimated azimuth phase sequence through the phase consistency measurement index and the minimum consistency order mapping: the reconstruction module is used for constructing a linear least square problem for representing the reconstruction of the coding structure based on the coding structure identification result to obtain a reconstructed azimuth phase sequence; and the generation module is used for carrying out phase consistent modulation on the intercepted SAR signals according to the reconstructed azimuth phase sequence, generating deception jamming signals and forwarding the deception jamming signals.
9. An electronic device, comprising: One or more processors; A memory for storing one or more programs; wherein the one or more programs, when executed by the one or more processors, cause the one or more processors to implement a spoofing jamming method for azimuth phase encoding SAR of any of claims 1-7.
10. A computer readable storage medium having stored thereon executable instructions which when executed by a processor enable the processor to implement a method of spoofing an azimuthal phase encoding SAR according to any of claims 1-7.

Description

Spoofing interference method and device for azimuth phase coding SAR Technical Field The invention belongs to the technical field of electronic support system (Electronic Support Measures, ESM) synthetic aperture radar (SYNTHETIC APERTURE RADAR, SAR) countermeasure, and particularly relates to a spoofing interference method and device for azimuth phase coding SAR. Background Synthetic Aperture Radar (SAR) is an active microwave imaging system, has the capability of imaging the ground all the time, all the weather and high resolution, and plays an irreplaceable role in the fields of military reconnaissance, civil mapping and the like. In order to protect own important targets from SAR reconnaissance threat, effective interference on SAR implementation becomes a research hotspot in the field of electronic countermeasure. The deception jamming can generate a designated false target in the SAR image by intercepting and forwarding a signal which is highly similar to the real echo in real time, has the advantages of low interference power, strong concealment, vivid effect and the like, and becomes an important development direction of SAR countermeasure technology. The prior deception jamming technology, such as a space-borne SAR deception jamming signal generation method based on space frequency interpolation, proposed by China patent (application number CN 202011240836.0) is mainly focused on improving the generation speed of a jamming template to realize large scene deception, and a SAR sea surface scene deception jamming method and system proposed by China patent (publication number CN 112180345A) is focused on incorporating sea surface dynamic information into the jamming template to improve simulation precision. However, the above studies are all based on a conventional SAR signal model, which implicitly assumes that the interfering object is a SAR system transmitting a conventional chirp signal. With the development of SAR technology, new system anti-interference waveforms are continuously emerging. The azimuth phase coding SAR is a typical new anti-interference system, and by adding an initial phase (including random phase coding, primary phase coding, secondary phase coding and packet phase coding) of agile pulse to a transmission signal in the azimuth direction, an interference signal behind a real echo is seriously mismatched with a phase agile matched filter at a receiving end, so that effective suppression of forward deception interference is realized. This technology has become an important development direction in the SAR anti-interference field. However, the prior art of spoofing does not consider the special system of azimuthal phase encoding at the beginning of the design. When the conventional method is adopted to implement interference on the azimuth phase coding SAR, the interference signal cannot have the same azimuth phase agility characteristic as the real echo, so that the energy of the interference signal cannot be effectively focused after matched filtering, and the interference effect is seriously inhibited or even completely disabled. At present, researches on how to break through an anti-interference barrier of azimuth phase coding SAR and realize effective deception interference of the SAR are blank. In view of the foregoing, there is a need for a spoofing interference method capable of sensing and matching with an azimuth phase code structure, so as to solve the problem that the prior art lacks interference effectiveness on the azimuth phase code SAR, and fill the technical gap in the field. Disclosure of Invention In order to solve the technical problems, the invention provides a spoofing interference method and device for a azimuth phase coding SAR, which ensure that a generated spoofing interference signal has a phase agility characteristic which is completely matched with an azimuth pulse inter-pulse phase coding structure of a target SAR through sensing, identifying and reconstructing, thereby breaking through an anti-interference barrier of the azimuth phase coding SAR. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: A method of spoofing an azimuthal phase encoded SAR, the method comprising: step 1, constructing an inverse distance modulation operator and an inverse azimuth modulation operator, and performing two-dimensional structured phase stripping on intercepted SAR signals to obtain an estimated azimuth phase sequence; Step 2, performing complex domain differential operation on the estimated azimuth phase sequence, constructing a phase consistency measurement index and a minimum consistency order mapping, and identifying the coding structure of the estimated azimuth phase sequence: Step 3, constructing a linear least square problem for representing the reconstruction of the coding structure based on the coding structure identification result to obtain a reconstructed azimuth phase sequence; and 4, according to the estim