CN-114966574-B - Active electronic camouflage interference method for resisting satellite-borne SAR reconnaissance

Abstract

The invention discloses an active electronic camouflage interference method for resisting satellite-borne SAR reconnaissance, which comprises the steps of S1, resolving an electromagnetic camouflage period taking topographic information into consideration, S2, generating false target electromagnetic signals based on scattering distribution increment, S3, performing distributed networking interference, firstly resolving the camouflage interference period by combining topographic information, establishing a target background template according to the existing radar image information, generating interference information of the false target in a scattering distribution increment mode, and finally modulating the interference information into radar signals in a distributed networking interference mode to be transmitted, thereby solving the problems of error accumulation and the like caused by the respective estimation of SAR motion parameters and signal parameters, and improving the fidelity and timeliness of electromagnetic camouflage.

Inventors

• WANG JIJUN
• ZHOU XIAO
• YU SONGLIN
• CHEN YUHUA
• LI BINGZHEN

Assignees

• 中国人民解放军军事科学院国防工程研究院

Dates

Publication Date

20260512

Application Date

20220412

Claims (2)

1. 1. An active electronic camouflage interference method for resisting satellite-borne SAR reconnaissance is characterized by comprising the following specific steps: S1, calculating an electromagnetic camouflage period taking the topographic information into consideration, namely reading the central position of a target area and peripheral DEM model data, and then calculating to obtain the setting time length of the camouflage time, wherein the specific operation is as follows: S101, reading central position and peripheral DEM model data of a target area, calculating height angles between the highest point of the ground feature and the target area under different azimuth angles, and taking the height angles as terrain cut-off height thresholds; Step S102, dynamically setting satellite orbit parameters and a sensor imaging angle range by utilizing autonomous development software, and acquiring instantaneous geometric information between a satellite and a target; Step S103, comparing whether the instantaneous altitude between the satellite and the target meets the imaging angle of the sensor and the terrain cut-off altitude threshold value at the same time, calculating the critical moment meeting the altitude condition by adopting a linear interpolation mode, and calculating the radar imaging effective duration of the target area by utilizing the critical moment; Step S104, calculating camouflage time setting, and performing electromagnetic signal camouflage according to satellite overhead effective time; S2, generating false target electromagnetic signals based on scattering distribution increment, namely performing down-conversion processing on the signals through a radar signal receiver, performing subsequent processing, and then performing up-conversion to carrier frequency for retransmission, wherein the method comprises the following specific operations: Step S201, after down-conversion processing at a radar signal receiver, sampling by an analog-to-digital converter and storing in a digital radio frequency memory, correcting by utilizing the existing radar image data according to the energy of a target radar detection unit and a detection radar detection unit, correcting and modulating the radar energy according to the processing gain and loss parameters of a radar system, and selecting a target template from a target template library as a background scene; step S202, performing texture synthesis on a template target and a background scene by using a texture synthesis technology, performing amplitude adjustment according to a radar system gain parameter to generate a virtual background, and calculating a backscattering coefficient difference value between the real scene and the virtual scene target according to the virtual background, wherein obvious edge marks easily appear at the edge part between the virtual target and the real scene; Step S203, simultaneously, calculating a shadow area of a real target, obtaining a modulation item which has no relation with azimuth fast time according to the shadow point position and a backscattering coefficient of a superimposed background, carrying out azimuth modulation on a signal, and obtaining an interference signal characteristic parameter by weighted summation; Step S204, processing each intercepted pulse sample by using a programmable target integrated circuit, performing delay processing, and modulating an electromagnetic signal of a camouflage background by using a distance modulator; step S205, converting the digital signal into an analog signal by using a digital-to-analog converter, and retransmitting the analog signal into a carrier frequency through up-conversion; S3, performing distributed networking interference, namely adopting an interference machine as a main station of the transceiver, additionally arranging a plurality of receivers as auxiliary stations for receiving radar signals, performing down-conversion processing on the received SAR signals, performing processing camouflage on the SAR signals, performing up-conversion processing and transmitting.
2. 2. The method of claim 1, wherein the specific operation of step S3 is as follows: To be used for Establishing an interference scene coordinate system parallel to a radar platform coordinate system for the center, wherein each time of the SAR platform The coordinates of (2) are: ; In the formula, The coordinate vector is represented as a vector of coordinates, Respectively coordinate components of the SAR platform, wherein T represents transposition operation of the coordinate vectors; suppose that by N auxiliary sites Representing, the coordinates are: ; where i denotes the i-th receiver, The coordinate components corresponding to the jammers under the SAR platform coordinate system are respectively provided, and the coordinate positions of the coordinate components are known relative to the main station jammers; The instantaneous slant distance between the main station jammer jam and the SAR platform is as follows: ; The instantaneous skew of the ith receiver to the SAR platform is: ; the distance difference between the receiver and the master station jam ; Due to the large scale time difference of SAR in the distance direction and the azimuth direction, according to the relative distance between different receiving stations and SAR, at each time Estimating the position of the SAR platform respectively, and locking the SAR at a correct position; ; ; ; ; In the formula, Is a receiver position matrix, And Respectively matrix constants; because only one unknown variable exists, the coordinates of the SAR platform can be accurately calculated by arranging more than three receivers: ; And performing radar signal delay compensation by using the resolved position information to generate a deception jamming signal: ; In the formula, Representing the spoofing jamming signal, Is radar pulse fast time, Slow time of radar pulse, Instantaneous pitch to be compensated for radar, Is a convolution operator of radar signals, The coordinate component of the jammer under the SAR platform coordinate system is represented by c, which is the light velocity, For the carrier frequency of the radar signal, Representing the phase term.

Description

Active electronic camouflage interference method for resisting satellite-borne SAR reconnaissance Technical Field The invention belongs to the technical field of radar signal transmission, and particularly relates to an active electronic camouflage interference method for resisting satellite-borne SAR reconnaissance. Background The synthetic aperture radar is an active microwave imaging radar, can monitor targets all day long and all weather long distance, and has high resolution in the distance direction and the azimuth direction. Along with the continuous improvement of the capacity of acquiring target information of the spaceborne SAR, the active electronic camouflage method aiming at the imaging characteristics of the spaceborne SAR is continuously improved, the method mainly utilizes a signal jammer to receive radar signals transmitted by the target radar, the signal is subjected to phase or frequency domain modulation, the modulated signal is transmitted, and when the radar receives the modulated radar echo signal, a false target after camouflage is generated during radar imaging, so that the camouflage effect is achieved. Aiming at the active electronic camouflage method, wang Chengli provides an electromagnetic camouflage interference frequency domain implementation method aiming at SAR signals, the real-time processing efficiency is improved, zhou Feng and other people provide various interference models for optimizing scattered wave interference, large scene interference, electromagnetic interference and the like aiming at the SAR signals electromagnetic camouflage interference, and Chen Saiwei and other people provide an electromagnetic camouflage interference approximate processing method based on DRFM. The analysis object of the SAR electromagnetic camouflage interference technology mainly aims at SAR scenes, and aims at SAR targets, such as adding false vehicles on uniform ground surfaces and changing farmlands into forest fields. The similarity between the modulated signal and the real signal directly influences the final camouflage effect, and the modulated signal depends on the scattering distribution characteristics of the target, the parameters of the detection radar system and the accurate acquisition of the relative motion relationship between the radar and the target. The difficulty of camouflage technology for SAR scenes and SAR targets is how to accurately acquire radar system parameters and parameter information of a transmitted signal. Chang Xin et al developed a discussion of the problem of reducing spoofing compliance, and propose a spoofing method based on two-dimensional separation that expands the main lobe width, creating a low resolution mosaic scene. Lin Xiaohong et al propose a w-k algorithm, which can rapidly convert a radar gray scene image into interference signals, and utilize an interference machine to transmit the interference signals in SAR side lobe areas one by one, so as to interfere important features of a real SAR image in real time. Dan Yunqi proposes a deception jamming technology based on scattering distribution increment, adjusts the template size of a block splicing synthesis technology, obtains a false scene with high similarity, zhao Bo and the like to artificially reduce the dependence of SAR track parameters, proposes a theoretical multi-receiver idea, and solves the problem of error amplification of a linear equation set in interference coefficient calculation. Wang Miaomiao improves the SAR deception jamming algorithm of the scattering distribution increment mode, and solves the problem that part of increment is negative. At present, the SAR electronic camouflage method generally directly superimposes a false scene on a real scene to obtain a deception scene, and combines a speckle model to learn that the deception scene and the real scene are randomly superimposed and are not the sum of simple scattering coefficients, so that the generated deception scene and the false target scene have low similarity and are easy to find camouflage signals. In addition, when the satellite-borne SAR electromagnetic camouflage signal is generated, the instantaneous position information of the target and the SAR platform is a key parameter affecting the effectiveness of the camouflage signal, and in order to improve the efficiency, the second-order Taylor series expansion is carried out on the slant range. Disclosure of Invention The invention aims to provide an active electronic camouflage interference method for resisting satellite-borne SAR reconnaissance so as to solve the problems in the background art. In order to achieve the purpose, the invention provides the following technical scheme that the active electronic camouflage interference method for resisting satellite-borne SAR reconnaissance is characterized by comprising the following specific steps: S1, calculating an electromagnetic camouflage period taking into consideration terrain information, namely read