Synthetic aperture radar interference method capable of hiding true and showing false in specific area
By deploying jammers and receivers in specific areas to acquire enemy SAR system parameters, and calculating and generating echoes from concealed and deceptive regions, the problem of insufficient jamming fidelity in existing technologies is solved, enabling precise masking and false target generation in SAR images.
Patent Information
- Application Number
- CN202511201866.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-26
- Publication Date
- 2025-12-05
AI Technical Summary
Existing synthetic aperture radar jamming techniques are difficult to achieve realistic concealment and deception in specific areas, and existing deception and forwarding jamming methods are not very flexible and difficult to accurately modulate the signals of enemy SAR systems.
One jammer and three receivers are deployed in a specific area. By passively receiving enemy SAR system parameters, the SAR simulated echo of the concealed area is calculated and generated, and the false target echo is simulated. The total echo is synthesized to perform deceptive jamming, thereby achieving the concealment of the true and the false of the SAR image.
It achieves precise masking of specific areas and generation of false targets in enemy SAR images, improving the realism and flexibility of the jamming, and can effectively mask real information and generate false targets.
Smart Images
Figure CN121069328A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to a synthetic aperture radar jamming method capable of showing true and false in a specific area, which can be used for implementing deception jamming on enemy synthetic aperture radar and belongs to the technical field of synthetic aperture radar signal processing. BACKGROUND
[0002] Synthetic aperture radar (SAR) is an important technical means in the fields of remote sensing observation and military reconnaissance. It works in the microwave band and is an active imaging radar capable of observing the earth at all times and in all weather. At present, the jamming methods for SAR systems mainly include passive jamming, noise suppression jamming and deception repeater jamming.
[0003] Passive jamming is to hide the target by coating or covering microwave wave-absorbing materials or to simulate a false target with strong backscattering by using corner reflectors. The essence of passive jamming is to change the scattering characteristics of the target by physical means. The technical difficulty of implementing passive jamming is not high, but the flexibility is poor.
[0004] Active jamming includes noise suppression jamming and deception repeater jamming. Noise suppression jamming refers to pushing up the noise jamming level of the SAR receiver by transmitting a high-power noise jamming signal, and even saturating it, so as to reduce the signal-to-noise ratio of the SAR echo. However, since the SAR echo processing is a coherent accumulation process, but the noise jamming cannot obtain coherent accumulation gain, therefore, the efficiency of noise suppression jamming is usually low, and the jammer needs to have a large power.
[0005] Deception repeater jamming is to modulate the amplitude and phase of the intercepted radar signal to simulate the SAR echo of a false target, and then transmit it. Unlike noise suppression jamming, the deception repeater jamming signal will obtain coherent gain in the SAR signal processing process, and the required jamming power is not very large. However, the technical difficulty of deception repeater jamming is relatively large, and real-time and accurate signal modulation needs to be performed according to the parameters of the enemy SAR system and the desired jamming purpose, otherwise it is difficult to achieve realistic jamming purpose, and the enemy can identify the jamming intention, which is also a common problem encountered in the implementation of this type of jamming. SUMMARY
[0006] The technical problem solved by the present application is to overcome the shortcomings of the prior art and provide a synthetic aperture radar jamming method capable of showing true and false in a specific area. The jamming signal form is accurately calculated by passive detection and collection of the parameters of the enemy synthetic aperture radar system, and active transmission of deceptive electromagnetic jamming is performed to achieve the effect that the specific area in the SAR image of the enemy is jammed and covered or false targets are generated.
[0007] The technical solution of the present application is:
[0008] A synthetic aperture radar jamming method capable of showing true and false in a specific area, comprising:
[0009] In a protected area requiring countermeasures against SAR system reconnaissance and detection, one jammer and three receivers are arranged in an approximate diamond shape in space;
[0010] According to the transmission signals of the SAR system received by the one jammer and the three receivers, the dynamic position of the SAR system antenna phase center and the original signals emitted by the SAR system are obtained;
[0011] The delay amount in the range direction and the Doppler frequency shift amount in the azimuth direction of the true area are calculated, and then the SAR simulation echo of the true area is generated, so that the SAR image information of the true area obtained by the enemy is jammed and blocked by the SAR simulation echo with greater energy;
[0012] The SAR simulation echo of the false area is calculated and generated, and the jammer simulates the false target echo signal, so that the SAR image obtained by the enemy appears false target image in the position where there is no target;
[0013] The generated SAR simulation echo of the true area and the SAR simulation echo of the false area are combined to obtain the total echo, and the jammer radiates the total echo in time sequence, so that the true and false of the protected area can be realized in the SAR image.
[0014] Further, the jammer is used to receive the SAR system incoming wave and transmit the jamming signal; the receiver is a passive receiver used to receive the SAR system incoming wave; when the one jammer and the three receivers are arranged in an approximate diamond shape in space, the jammer is located at the near end of the SAR observation strip; the jammer and the receiver can be time-synchronized and communication-interconnected.
[0015] Further, the transmission signals of the SAR system received by the one jammer and the three receivers are used to obtain the dynamic position of the SAR system antenna phase center, specifically:
[0016]
[0017] wherein, t S represents the time when the SAR system starts to transmit the radar signal in a certain pulse, t A represents the time when the jammer starts to receive the radar signal, t B , t C , t D respectively represent the time when the three receivers start to receive the radar signal, c represents the speed of light; (x S , y S , h S ) represents tS The position of the SAR system antenna phase center in the northeast-northeast coordinate system at a given time is denoted as the position vector. (x A ,y A ,h A The position of the jammer in the northeast-central coordinate system is represented by denoted as the position vector. [·] T This represents the transpose operation of a matrix or vector, (x B ,y B ,h B ), (x C ,y C ,h C ), (x D ,y D ,h D The positions of the three receivers in the northeast celestial coordinate system are represented by the following vectors: ...
[0018] Furthermore, the SAR system operates according to a fixed pulse time interval t PRT The SAR system periodically and continuously transmits radar pulse signals, and correspondingly, the jammer and receiver continuously receive radar pulse signals. The SAR system, jammer, and receiver all record a sequence of pulse start times. When determining the dynamic position of the SAR system antenna phase center, the selected t... A t B t C t D They must correspond to the same pulse.
[0019] Furthermore, select t A t B t C t D The specific method is as follows:
[0020] For the start time value t of a certain received pulse recorded by the jammer A In the pulse start time sequence recorded by each receiver, and t A The nearest time value is t. B t C t D .
[0021] Furthermore, the raw signal emitted by the SAR system is specifically as follows:
[0022] Using t measured at each station A t B t C t D The time sequence of the SAR system's transmitted pulses is obtained by solving the problem.S and the corresponding position sequence (x S ,y S ,h S ), that is, the track information of the SAR system is obtained; by statistically averaging the track information, the average velocity vector of the SAR system in the time period corresponding to the time sequence is obtained The specific method is as follows:
[0023]
[0024] Wherein, t Smax , t Smin are the minimum value and the maximum value in the time sequence t S solved, (x Smin ,y Smin ,h Smin ), (x Smax ,y Smax ,h Smax ) are the values in the position sequence (x S ,y S ,h S ) corresponding to the time t Smax , t Smin ;
[0025] The jammer receives the transmitting signal of the SAR system, and records the received signal waveform S R corresponding to different receiving time t A ;
[0026] The distance delay effect and the Doppler modulation effect in the received signal waveform S R received by the jammer are removed, and then the original signal S0 emitted by the SAR system is obtained, and the specific method is as follows: the displacement vector of the SAR system position to the position of the jammer is calculated The vector angle between and is calculated Wherein, “·” represents the vector dot product operation, and |·| represents the vector modulus operation; the Doppler frequency shift of the SAR signal received by the jammer is calculated λ is the signal wavelength; and the original signal S0 emitted by the SAR system is:
[0027]
[0028] Wherein, f τ is the fast time frequency variable, FFT τ {·} is the fast Fourier transform operation in the fast time direction, and IFFT τ {·} is the fast inverse Fourier transform operation in the fast time direction.
[0029] Further, the distance delay and azimuth Doppler shift of the false region are calculated, and then the SAR simulation echo of the false region is generated, specifically:
[0030] Firstly, the echo distance delay information of the false region is determined according to the transmission timing, the jammer position and the false region position; the coordinates of the center position point of the kth false region are denoted as The echo time delay required by the jammer is:
[0031]
[0032] Then, the frequency shift information of the transmitted signal is determined according to the relative motion relationship between the SAR system and the false region, the position of the jammer and the angle of view relative to the SAR system, and the Doppler shift required by the echo of the jammer is:
[0033]
[0034] Thirdly, the amplitude modulation information of the signal is determined according to the image content of the false region, that is, the echo signal required to be simulated by the jammer.
[0035] Further, the echo signal required to be simulated by the jammer is determined, specifically:
[0036] Firstly, a set of position points covering each region is randomly generated in the horizontal plane of the false region according to the range of the false region, and the distance between any point in each region and the nearest point is much smaller than Where B is the 3dB bandwidth of the SAR system transmitted signal waveform;
[0037] The coordinates of the nth position point are denoted as The total number of position points is denoted as N; the amplitude of the jammer required to generate the echo of the nth position point is denoted as σ A,n The size is several times the amplitude information of the strongest scattering position of the false region when there is no jammer; and the echo signal required to be simulated by the jammer is:
[0038]
[0039] Where,
[0040] is a random phase uniformly distributed in [0, 2π) randomly generated.
[0041] Further, the SAR simulation echo of the false region is generated, specifically:
[0042] According to the image content of the false target, the position information of each scattering point of the false target is determined, and the coordinates of the mth position point are denoted as The total number of position points is denoted as M;
[0043] At the mth position point, the amplitude information corresponding to the jammer is denoted as σ A3,m , and the phase information corresponding to the jammer is denoted as The echo signal required to be simulated by the jammer is:
[0044]
[0045] Further, the total echo is S2(t S )+S3(t S ),
[0046] By deploying the jammer, the total echo S2(t S )+S3(t S ) is radiated in time sequence, so that the true-to-false hiding effect in the protected area can be achieved in the SAR image of the enemy.
[0047] Compared with the prior art, the present application has the following beneficial effects:
[0048] (1) The synthetic aperture radar jamming method for true-to-false hiding in a specific area provided by the present application can invert the dynamic position of the SAR antenna phase center by arranging one jammer and three receivers in the key protected area, so that the influence of the range delay and the azimuth Doppler modulation in the SAR transmitting signal can be accurately removed, and then the SAR original signal can be obtained.
[0049] (2) The synthetic aperture radar jamming method for true-to-false hiding in a specific area provided by the present application can calculate and generate the SAR simulated echo of the "true-to-false hiding" area, so that the SAR image information of the area obtained by the enemy is "white jamming blocked", thereby achieving the "true-to-false hiding" effect.
[0050] (3) The synthetic aperture radar jamming method for true-to-false hiding in a specific area provided by the present application can calculate and generate the SAR simulated echo of the "true-to-false hiding" area, so that the SAR image obtained by the enemy appears a false target image in the position where there is no target, thereby achieving the "true-to-false hiding" effect. BRIEF DESCRIPTION OF DRAWINGS
[0051] Figure 1 It is a scene layout schematic diagram of the synthetic aperture radar jamming method for true-to-false hiding in a specific area.
[0052] Figure 2 It is a flowchart of the synthetic aperture radar jamming method for true-to-false hiding in a specific area. DETAILED DESCRIPTION
[0053] The specific embodiments of the present application are described in further detail below with reference to the accompanying drawings.
[0054] In order to implement accurate and high-fidelity deceptive jamming on the enemy synthetic aperture radar, and achieve the jamming intention of hiding the true and showing the false, the present application provides a synthetic aperture radar jamming method capable of hiding the true and showing the false in a specific area, which is suitable for countering the reconnaissance of the enemy synthetic aperture radar system on the protected area (i.e. the specific area) by using electromagnetic jamming means, and can obtain the parameters of the enemy synthetic aperture radar system through passive detection, and accurately calculate the form of the jamming signal according to the parameters, and actively emit deceptive electromagnetic jamming, so as to achieve the effect that the specific area in the SAR image of the enemy is jammed and covered or false targets are generated.
[0055] The synthetic aperture radar jamming method capable of hiding the true and showing the false in a specific area provided by the present application belongs to the deceptive repeater jamming mode, solves the problem of insufficient fidelity of the existing SAR deceptive jamming means, and further realizes the jamming intention of hiding the true and showing the false.
[0056] The basic idea of the present application can be summarized as follows:
[0057] Firstly, one jammer and three detectors are arranged in the key protected area which needs to be countered against the reconnaissance and detection of the enemy SAR system, and the one jammer and the three detectors are approximately rhombus distributed in space.
[0058] Secondly, the transmission signal of the SAR system is received by the one jammer and the three detectors, on the one hand, the dynamic position of the phase center of the SAR antenna is inverted; on the other hand, based on the received SAR transmission signal, after removing the influence of the range delay and the azimuth Doppler modulation, the SAR original signal is obtained.
[0059] Then, the range delay amount and the azimuth Doppler shift amount of the hidden true area are calculated, and the SAR echo of the hidden true area is calculated and generated. For the area to be hidden, the SAR image information of the area obtained by the enemy is "white jamming blocked" by simulating greater energy through the echo.
[0060] Next, the SAR echo of the "show false" area is calculated and generated by a similar method. For the area to be shown false, the SAR image obtained by the enemy appears a false target image at the position where there is no target by simulating a false target echo signal through the jammer.
[0061] Finally, the SAR simulation echo of the hidden true area and the SAR simulation echo of the shown false area generated in the above two steps are calculated and combined to obtain the total echo, and the total echo is radiated in time sequence by the jammer, so that the hidden true and shown false of the specific area in the SAR image can be realized.
[0062] Embodiment:
[0063] AsFigure 2 The implementation steps of the synthetic aperture radar jamming method that can show false in a specific area are as follows:
[0064] Step 1: In the key protection area that needs to be against enemy SAR system reconnaissance and detection, one jammer and three receivers are arranged, as shown in the figure. Figure 1
[0065] The jammer has the functions of receiving the incoming wave of the SAR system and transmitting the jamming signal; the receiver has the function of receiving the incoming wave of the SAR system and belongs to a passive receiver. One jammer and three receivers are approximately diamond-shaped in space, and the jammer is located at the near end of the SAR observation strip. The jammer and the receiver can be time-synchronized and communicatively interconnected.
[0066] Step 2: Use one jammer and three receivers to receive the transmitted signals of the SAR system to obtain the dynamic position of the SAR antenna phase center and the original signals emitted by the SAR system. The method is as follows:
[0067] First, the positions of the SAR system antenna phase center at different times are calculated, and the specific calculation method is as follows:
[0068]
[0069] Where t S represents the time when the SAR system starts to transmit the radar signal in a certain pulse, t A represents the time when the jammer starts to receive the radar signal, t B , t C , and t D represent the times when the three receivers start to receive the radar signal, respectively; (x S , y S , h S ) represents the position of the SAR system antenna phase center in the “east, north, and altitude” coordinate system (i.e., the northeast celestial coordinate system) at time t S , denoted as position vector (x A , y A , h A ) represents the position of the jammer in the “east, north, and altitude” coordinate system, denoted as position vector [·] T represents the transpose operation of a matrix or a vector, (x B , y B , h B ), (x C , y C , h C ), and (x D , y D , hD ) respectively represent the positions of the three interceptors in the "east, north, height" coordinate system, and are respectively denoted as position vectors c represents the speed of light.
[0070] Generally, the SAR system will emit radar pulse signals at fixed pulse time intervals t PRT The radar pulse signals are continuously emitted periodically, and the jammer and the interceptors also continuously receive the radar pulse signals. In other words, the enemy SAR system, the jammer and the interceptors of our side all record a sequence of pulse start time points, but the correspondence between each time point value in the sequence and the number of the pulse (in other words, when solving the above equation, it is necessary to ensure that the selected t A , t B , t C , t D correspond to the same pulse) needs to be determined as follows:
[0071] For a received pulse start time value t A recorded by the jammer, the nearest neighbor time value in the sequence of pulse start time points recorded by each interceptor is t A , t B , t C , t D . The reason for this is that the time difference in the reception of the same pulse start time point by different stations (jammer, interceptor) is usually the distance delay, and the distance difference between the stations and the SAR system in the corresponding scenario of the present application is obviously less than ten kilometers. According to the usual case of SAR, the time difference between different pulse start time points is usually of the order of sub-milliseconds, which is converted into a delay distance of about one hundred kilometers. In other words, the arrival time difference of the same SAR pulse at different stations is much smaller than the arrival time difference between different pulses.
[0072] According to the method in the preceding paragraph, the measured values of t A , t B , t C , t D can be obtained, and then the position measurement values (x A , y A , h A ), (x B , y B , h B ), (x C , y C , h C ), (x D , y D , h D ) of each station are substituted into the above equation, so that t S and (x S , y S , hS the values of t
[0073] Then, the t A , t B , t C , t D time series measured by each station are used to solve the t S time series of the SAR system transmitting pulses and the corresponding position series (x S , y S , h S ), that is, the track information of the SAR system. By statistically averaging the track information in this period, the average speed vector of the SAR system in this period can be obtained. The specific method is as follows:
[0074]
[0075] where t Smax , t Smin are the minimum value and the maximum value in the solved t S time series, (x Smin , y Smin , h Smin ) and (x Smax , y Smax , h Smax ) are the values corresponding to t Smax and t Smin in the solved position series (x S , y S , h S ).
[0076] Next, the jammer receives the transmitting signal of the SAR system and records the received signal waveform S A corresponding to different receiving times t R .
[0077] Finally, the range delay effect and the Doppler modulation effect in the SAR signal S R received by the jammer are removed, and the original signal S0 emitted by the SAR system is obtained. The specific method is as follows: the displacement vector of the SAR system position to the jammer position is calculated The vector angle between and is calculated where “·” represents the vector dot product operation, and |·| represents the vector modulus operation; the Doppler shift of the SAR signal received by the jammer is calculated Then, the original signal S0 emitted by the SAR system is:
[0078]
[0079] where f τ is the fast time frequency variable, FFT τ is the fast Fourier transform operation in the fast time direction, IFFT τ is the inverse fast Fourier transform operation in the fast time direction.
[0080] Generally, the waveform of each pulse of the SAR system remains fixed, but the relative position relationship between the SAR system and the receiving station changes over time, and the relative velocity relationship changes, so the Doppler modulation introduced at different times is different.
[0081] Step 3: Calculate the range delay and azimuth Doppler shift of the true area, and then generate the SAR echo of the true area. For the pseudo-true area, more energy is simulated through the echo, so that the SAR image information of the area obtained by the enemy is "white jamming shielding". The so-called greater energy is relative to the normal echo of the SAR system. The present application is to emit a greater energy jamming signal to cover the real echo signal to achieve the purpose of deception. The enemy's SAR image presents a high light or a white.
[0082] The specific way is:
[0083] First, according to the transmission timing, the jammer position, and the "true" area position, the echo distance delay information of the "true" area is determined. The coordinates of the center position point of the kth pseudo-true area are denoted as The echo time delay required by the jammer is:
[0084]
[0085] Then, according to the relative motion relationship between the SAR and the true area, the position of the jammer and the angle of view relative to the SAR, the frequency shift information of the transmitted signal is determined. The echo Doppler shift required by the jammer is:
[0086]
[0087] Thirdly, according to the image content of the pseudo-coverage stealth area, the amplitude modulation information of the signal is determined, which can be: 1, high energy information, 2, based on the simulation generation information of other high light scenes (which can be covered).
[0088] In specific implementation, first, according to the range of all the "true" areas, a set of position points covering each area is randomly generated in the horizontal plane of the "true" area using a random number generation method. The distance between any point in each area and the nearest point should be much smaller than where B is the 3dB bandwidth of the SAR transmission signal waveform. The coordinates of the nth position point are denoted as Let the total number of position points be N. The amplitude of the jammer required to generate the echo of the nth position point is denoted as σ A,n , and the size is several times the amplitude information corresponding to the position with the strongest scattering when there is no jammer in the stealth area to be covered. Then the echo signal simulated by the jammer is:
[0089]
[0090] , wherein,
[0091] is a random phase uniformly distributed in [0, 2π) randomly generated.
[0092] Step 4: Calculate the SAR echo generated by the false area. For the area to be demonstrated as false, the jammer simulates the false target echo signal so that the SAR image obtained by the enemy appears false target image at the position where there is no target. The specific steps are as follows:
[0093] According to the image content to be demonstrated as false, the position information of each scattering point of the false target is determined, and the coordinates of the mth position point are denoted as Let the total number of position points be M. At the mth position point, the amplitude information corresponding to the jammer is denoted as σ A3,m , and the phase information corresponding to the jammer is denoted as Then the echo signal simulated by the jammer is:
[0094]
[0095] Step 5: Calculate and combine the SAR simulation echo of the true area generated in step 3 and the SAR simulation echo of the false area generated in step 4 to obtain the total echo S2(t S )+S3(t S ). Using the jammer deployed in step 1, the total echo S2(t S )+S3(t S ) is radiated in time sequence, so that the "true demonstration false" of the protected area can be realized in the SAR image.
[0096] The part of the present application not described in detail is common knowledge to those skilled in the art.
Claims
1. A synthetic aperture radar jamming method capable of deceiving true and deceiving false in a specific area, characterized in that, The application relates to a synthetic aperture radar (SAR) jamming method capable of hiding true and showing false in a specific area. In a protection area needing to resist detection of a SAR system, one jammer and three receivers are arranged in a nearly rhombic space distribution; According to the received transmission signals of the SAR system by the one jammer and the three receivers, the dynamic position of the antenna phase center of the SAR system and the original signals emitted by the SAR system are obtained; The distance delay and the azimuth Doppler frequency shift of the hidden true area are calculated, and then the SAR simulation echo of the hidden true area is generated, so that more energy is simulated by the SAR simulation echo, and the SAR image information of the hidden true area obtained by the enemy is shielded by the jamming; The SAR simulation echo of the false area is calculated, and the jammer simulates the false target echo signal, so that the SAR image obtained by the enemy appears false target image in the position without the target; The generated SAR simulation echo of the hidden true area and the SAR simulation echo of the false area are combined to obtain total echo, and the jammer radiates the total echo according to time sequence, so that the hidden true and false in the protection area can be realized in the SAR image.
2. The method of claim 1, wherein the synthetic aperture radar jamming is made false in a specific area. The jammer is used for receiving the incoming wave of the SAR system and emitting the jamming signal; the receiver is a passive receiver and is used for receiving the incoming wave of the SAR system; when the one jammer and the three receivers are arranged in a nearly rhombic space distribution, the jammer is located at the near distance end of the SAR observation strip; the jammer and the receiver can be time-synchronized and communicatively interconnected.
3. The method of claim 1, wherein: the synthetic aperture radar is a spotlight synthetic aperture radar. According to the received transmission signals of the SAR system by the one jammer and the three receivers, the dynamic position of the antenna phase center of the SAR system is obtained, and the original signals emitted by the SAR system are obtained. where t S represents the time when the SAR system starts to transmit radar signals in a certain pulse, t A represents the time when the jammer starts to receive the radar signals, t B , t C , t D respectively represent the time when the three interceptors start to receive the radar signals, c represents the speed of light; (x S , y S , h S ) represents the position of the antenna phase center of the SAR system in the East-North-Up coordinate system at the time t S , and is recorded as the position vector (x A , y A , h A ) represents the position of the jammer in the East-North-Up coordinate system, and is recorded as the position vector [·] T represents the transpose operation of a matrix or a vector, (x B , y B , h B ), (x C , y C , h C ), (x D , y D , h D ) respectively represent the positions of the three interceptors in the East-North-Up coordinate system, and are respectively recorded as the position vectors The original signals emitted by the SAR system are obtained. SAR system according to fixed pulse time interval t PRT Periodic continuous emission radar pulse signal, accordingly, jammer and intercept receiver continuously receive radar pulse signal, SAR system, jammer and intercept receiver will record a pulse starting time sequence, in solving the dynamic position of SAR system antenna phase center, selected t A , t B , t C , t D Need to correspond to the same pulse.
5. A synthetic aperture radar jamming method capable of concealing the true nature of a radar in a specific area, as described in claim 4, is characterized in that: The method for selecting t A , t B , t C , t D is specifically: the value of the start time of a certain reception pulse recorded by the jammer A In the sequence of start times of pulses recorded by each of the intercept receivers, the value of t A The value of the nearest start time is t B , t C , t D .
6. The method of claim 4, wherein: the synthetic aperture radar is a spotlight synthetic aperture radar. The original signals emitted by the SAR system are obtained. The time sequence t A , t B , t C , t D measured by each station is used to solve the time sequence t S of the SAR system transmitting pulse and the corresponding position sequence (x S , y S , h S ), that is, the track information of the SAR system is obtained; the average speed vector of the SAR system in the time period corresponding to the time sequence is obtained by statistically averaging the track information. The specific method is as follows: wherein t Smax , t Smin are the minimum and maximum values in the sequence of times t S solved, (x Smin , y Smin , h Smin ), (x Smax , y Smax , h Smax ) are the values in the sequence of positions (x S , y S , h S ) corresponding to the times t Smax , t Smin solved. The jammer receives the transmitting signal of the SAR system, records the different receiving time t A The corresponding receiving signal waveform S R ; The received signal waveform S received by the jammer is removed R The distance delay effect and Doppler modulation effect in the received signal waveform S are removed, and the original signal S0 emitted by the SAR system is obtained, and the specific method is as follows: the displacement vector of the SAR system position to the jammer position is calculated The displacement vector is calculated The vector angle of the displacement vector and the velocity vector of the SAR system is calculated The vector angle is calculated Wherein, “·” represents the vector dot product operation, and |·| represents the vector modulus operation; the Doppler frequency shift of the SAR signal received by the jammer is calculated λ is the signal wavelength; and the original signal S0 emitted by the SAR system is as follows: where f τ is the fast time frequency variable, FFT τ {·} is the fast Fourier transform operation in the fast time direction, IFFT τ {·} is the inverse fast Fourier transform operation in the fast time direction. The distance delay and the azimuth Doppler frequency shift of the hidden true area are calculated, and then the SAR simulation echo of the hidden true area is generated, so that more energy is simulated by the SAR simulation echo, and the SAR image information of the hidden true area obtained by the enemy is shielded by the jamming. The SAR simulation echo of the false area is calculated, and the jammer simulates the false target echo signal, so that the SAR image obtained by the enemy appears false target image in the position without the target. First, according to the transmission timing, the jammer position and the false-echo area position, the echo distance delay information of the false-echo area is determined; the central position point coordinate of the kth false-echo area is marked as The echo delay amount required by the jammer is: The SAR simulation echo of the false area is calculated, and the jammer simulates the false target echo signal, so that the SAR image obtained by the enemy appears false target image in the position without the target. 8. The method of claim 7, wherein: the synthetic aperture radar is a spotlight synthetic aperture radar. First, according to the range of the hidden true area, a set of position points covering each area is randomly generated in the horizontal plane of the hidden true area by using a random number generation method. The distance between an arbitrary point in each area and the nearest point to it should be much smaller than where B is the 3dB bandwidth of the SAR system transmitted signal waveform; Let the coordinate of the nth position point be Let the total number of position points be N; the amplitude of the jammer required to generate the echo of the nth position point be σ A,n The size is several times the amplitude information corresponding to the position with the strongest scattering when there is no jammer; then the echo signal required for the jammer to simulate is: wherein, is a randomly generated random phase uniformly distributed in [0, 2π).
9. The method of claim 8, wherein: the synthetic aperture radar is a spotlight synthetic aperture radar. According to the image content to be shown, the position information of each scattering point of the false target is determined, and the coordinates of the mth position point are marked as The total number of position points is marked as M. At the mth position point, the corresponding amplitude information of the jammer is denoted as σ A3,m The corresponding phase information of the jammer is denoted as The echo signal required to be simulated by the jammer is:
10. A synthetic aperture radar jamming method capable of concealing the true nature of a target area and revealing a false one in a specific region, as described in claim 9, is characterized in that: The total echo is S2(t S )+S3(t S ), using the deployed jammer, the total echo S2(t S )+S3(t S ) is radiated according to the time sequence, that is, the true and false can be realized in the enemy SAR image.