An external radiation source dual-base imaging system and method under a motion platform

Abstract

The application relates to the technical field of bistatic radar imaging, in particular to an external radiation source bistatic imaging system and method under a motion platform. The system comprises a motion platform provided with a GPS signal receiving module, a high-dynamic receiving platform posture measuring module, a high-dynamic receiving platform position error calculating module, a one-dimensional range image processing module, a range upsampling module, a grid dividing module and a reverse projection two-dimensional imaging module. Firstly, the position of the motion platform can be determined more accurately through compensation and correction of the posture of the motion platform; then, high-resolution two-dimensional focusing processing of a region of interest is realized through reverse projection, and a bistatic two-dimensional imaging result of the region of interest, namely a bistatic two-dimensional figure of the region of interest, is obtained.

Description

Technical Field

[0001] This invention relates to the field of bistatic radar imaging technology, and more particularly to a bistatic imaging system and method for an external radiation source under a moving platform. Background Technology

[0002] Global Navigation Satellite System-Reflectometry (GNSS-R) is a new branch of the GNSS field that has gradually developed since the 1990s. It can achieve remote sensing of the Earth by processing reflected signals. Commonly used GNSS signals include the US GPS signal, China's BeiDou signal, Europe's Galileo signal, and Russia's GLONAS signal.

[0003] The GNSS-R system fully utilizes the global coverage advantage of navigation satellites. It not only has the low power consumption advantage of external radiation source radar, but also has the advantages of high deployment orbit and wide coverage. It can effectively solve the problems of insufficient coverage of ground-based radar systems and low-altitude blind spots caused by the curvature of the earth, and can realize large-scale detection and imaging of the earth.

[0004] In GNSS-R Earth imaging, the Microwave Integrated Systems Laboratory at the University of Birmingham, UK, conducted a bistatic imaging experiment in 2012 using ground-based fixed receivers and vehicle-mounted receivers with GLONASS and Galileo signals as external radiation sources. Beijing Institute of Technology analyzed the impact of the ionosphere on GEO-SAR imaging and conducted experimental verification using point target simulation and GPS signals. Furthermore, domestic institutions such as Beijing University of Aeronautics and Astronautics, Xi'an University of Electronic Science and Technology, and University of Electronic Science and Technology of China have also conducted related research. GNSS-R technology not only does not occupy new frequency band resources but also has advantages such as simple equipment, high flexibility, and strong concealment, showing broad application prospects in the future field of remote sensing.

[0005] Current domestic research on bistatic imaging of external radiation sources mainly focuses on ground-based scenarios (fixed ground receiving platforms and vehicle-mounted receiving platforms), with limited research on airborne motion scenarios, especially bistatic imaging of external radiation sources under moving platforms. Due to the non-ideal motion of the moving platform, the slant range history of the radar echo signal changes, causing traditional bistatic imaging methods to fail and resulting in defocusing. Therefore, it is necessary to conduct research on bistatic imaging methods for external radiation sources under moving platforms. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a dual-base imaging system and method for an external radiation source under a motion platform.

[0007] The technical solution of the dual-base imaging system with external radiation source under a motion platform according to the present invention is as follows:

[0008] The motion platform includes a GPS signal receiving module, a high dynamic range receiving platform attitude measurement module, a high dynamic range receiving platform position error calculation module, a one-dimensional range image processing module, a range upsampling module, a mesh generation module, and a back projection two-dimensional imaging module.

[0009] The GPS signal receiving module is used to: receive the direct wave signal from the GPS satellite and the echo signal from the scene of interest, and calculate the attitude information of the GPS satellite based on the direct wave signal from the GPS satellite;

[0010] The high dynamic receiving platform attitude measurement module is used to: acquire the position information and velocity information of the motion platform;

[0011] The high dynamic receiving platform position error calculation module is used to: calculate the position error information of the motion platform in the geocentric coordinate system based on the position information and velocity information of the motion platform, and correct the position information of the motion platform based on the position error information to obtain the corrected position and attitude information of the motion platform in the geocentric coordinate system.

[0012] The one-dimensional range image processing module is used to: sequentially perform range-direction pulse compression, motion correction, and phase compensation on the echo signal of the scene of interest to obtain a one-dimensional range image imaging result;

[0013] The distance upsampling module is used to: perform upsampling processing on the one-dimensional distance image imaging result to obtain a refined upsampling result;

[0014] The grid division module is used to: divide the imaging region corresponding to the scene of interest into grids according to the resolution and imaging latitude and longitude index requirements, so as to obtain multiple grid units;

[0015] The back-projection two-dimensional imaging module is used to: calculate the delay component of any grid cell based on the attitude information of the GPS satellite and the corrected position and attitude information of the motion platform, and back-project the refined upsampling result according to the corresponding geographical location to obtain the high-resolution imaging result of the grid cell, until the high-resolution imaging result of each grid cell is obtained, and combine the high-resolution imaging results of each grid cell to obtain the bi-base two-dimensional imaging result of the scene of interest.

[0016] The beneficial effects of the external radiation source bistatic imaging system under a motion platform according to the present invention are as follows:

[0017] First, by compensating and correcting the attitude of the motion platform, the position of the motion platform can be determined more accurately. Then, by back projection, high-resolution two-dimensional focusing processing of the region of interest is achieved, resulting in a bi-base two-dimensional imaging result of the scene of interest, i.e., a bi-base two-dimensional graphic of the scene of interest.

[0018] The technical solution of the dual-base imaging method for an external radiation source under a motion platform according to the present invention is as follows:

[0019] The above-described dual-base imaging system using an external radiation source on a motion platform includes the following methods:

[0020] The GPS signal receiving module receives the direct wave signal from the GPS satellite and the echo signal from the scene of interest, and calculates the attitude information of the GPS satellite based on the direct wave signal from the GPS satellite.

[0021] The high dynamic receiving platform attitude measurement module acquires the position and velocity information of the motion platform;

[0022] The high dynamic receiving platform position error calculation module calculates the position error information of the motion platform in the geocentric coordinate system based on the position information and velocity information of the motion platform, and corrects the position information of the motion platform based on the position error information to obtain the corrected position and attitude information of the motion platform in the geocentric coordinate system.

[0023] The one-dimensional range image processing module sequentially performs range-direction pulse compression, motion correction, and phase compensation on the echo signal of the scene of interest to obtain a one-dimensional range image imaging result.

[0024] The distance upsampling module performs upsampling processing on the one-dimensional distance image imaging result to obtain a refined upsampling result;

[0025] The grid division module divides the imaging region corresponding to the scene of interest into multiple grid units according to the resolution and imaging latitude and longitude index requirements.

[0026] The back-projection two-dimensional imaging module calculates the delay component of any grid cell based on the attitude information of the GPS satellite and the corrected position and attitude information of the motion platform, and back-projects the refined upsampling result according to the corresponding geographical location to obtain the high-resolution imaging result of the grid cell, until the high-resolution imaging result of each grid cell is obtained. The high-resolution imaging results of each grid cell are combined to obtain the bi-base two-dimensional imaging result of the scene of interest.

[0027] The beneficial effects of the dual-base imaging method for external radiation sources under a motion platform according to the present invention are as follows:

[0028] First, by compensating and correcting the attitude of the motion platform, the position of the motion platform can be determined more accurately. Then, by back projection, high-resolution two-dimensional focusing processing of the region of interest is achieved, resulting in a bi-base two-dimensional imaging result of the scene of interest, i.e., a bi-base two-dimensional graphic of the scene of interest. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of a dual-base imaging system with an external radiation source under a motion platform according to an embodiment of the present invention;

[0030] Figure 2 It is a scene with real pixel art;

[0031] Figure 3 The results are imaging results of a binary target from a dot matrix external field radiation source using the traditional P-code method.

[0032] Figure 4 This is the result of bistatic imaging of the target external field radiation source of the P-code dot matrix of the present invention;

[0033] Figure 5 The scene depicts a car outline composed of dot matrix objects.

[0034] Figure 6 This is a bistatic imaging result of an external field radiation source of a surface target using the traditional P-code method;

[0035] Figure 7 This is the result of bistatic imaging of the P-code surface target external field radiation source according to the present invention.

[0036] Figure 8 This is a schematic flowchart of a dual-base imaging method for an external radiation source under a motion platform according to an embodiment of the present invention. Detailed Implementation

[0037] like Figure 1 As shown, an embodiment of the present invention provides a dual-base imaging system for an external radiation source under a motion platform, comprising a motion platform having a GPS signal receiving module 210, a high dynamic receiving platform attitude measurement module 220, a high dynamic receiving platform position error calculation module 230, a one-dimensional range image processing module 240, a range upsampling module 250, a mesh generation module 260, and a back projection two-dimensional imaging module 270.

[0038] The GPS signal receiving module 210 is used to: receive the direct wave signal from the GPS satellite and the echo signal from the scene of interest, and calculate the attitude information of the GPS satellite based on the direct wave signal from the GPS satellite.

[0039] The GPS signal receiving module 210 includes a right-hand circularly polarized antenna and a left-hand circularly polarized antenna. The right-hand circularly polarized antenna is used to receive the direct wave signal from GPS satellites, and the left-hand circularly polarized antenna is used to receive the echo signal from the scene of interest.

[0040] Direct wave signals from GPS satellites d (t-τ d )for:

[0041] s d (t-τ d ) = C PRN (t-τ d )D(t-τ d )exp[j2πf c (t-τ d )]

[0042] Where t represents fast time, τ d C is the time delay of the direct wave signal. PRN (t-τ d ) represents: t-τ d The pseudo-random sequence code (PRN) corresponding to time t mainly includes C / A codes and P codes, D(t-τ) d ) represents: t-τ d The corresponding D-code data code at each time point, the code rate of the D-code data code is typically 50Hz, and the D-code data code is modulated on the corresponding carrier using binary phase shift keying (BPSK). c Let be the carrier frequency of the direct wave signal, j denote the imaginary part, and 2πf c (t-τ d ) represents t-τ d The phase of a moment.

[0043] GPS satellites transmit GPS signals to the scene of interest. The scene of interest reflects the GPS signals back to a left-hand circularly polarized antenna, resulting in the echo signal s from the scene of interest. r (t):

[0044] s r (t)=C PRN (t-τ r )D(t-τ r )exp[j2πf c (t-τ r )]

[0045] =C PRN (t-τ r )D(t-τ r )exp(j2πf c t)exp(-j2πf c τ r )

[0046] Based on the GPS satellite data code and the GPS satellite attitude information calculated from the GPS satellite direct wave signal, the following is given: [xT (t m ),y T (t m ),z T (t m )], where τ r t-τ represents the time taken for the distance from the satellite to the target, and then from the target's reflection back to the receiver. r Indicates after a delay τ r In the short time that followed, C PRN (t-τ r ) and D(t-τ r ) represent t-τ respectively r The pseudo-random code signal and the data code signal. t m Indicates location and time, x T (t m ), y T (t m ) and z T (t m ) represent t respectively m The instantaneous x-coordinate, y-coordinate, and y-coordinate of the GPS satellite at any given time.

[0047] The high dynamic range receiving platform attitude measurement module 220 is used to: acquire the position and velocity information of the motion platform, specifically:

[0048] Location information is: [x R (t m ),y R (t m ),z R (t m )], where t m Indicates location and time, x R (t m ),y R (t m ) and z R (t m ) represent t respectively m The instantaneous horizontal axis, instantaneous vertical axis, and instantaneous vertical axis of the high dynamic range receiving platform.

[0049] Since the position data acquired by the inertial measurement unit is longitude, latitude, and altitude information in geodetic coordinates, it is necessary to convert the position information of the high dynamic range receiving platform to the horizontal, vertical, and vertical coordinate information of the ECEF coordinate system. The conversion formula is as follows:

[0050]

[0051] Where e is the Earth's eccentricity (B(t)) m ),L(t m ),H(tm )) respectively represent t m The latitude, longitude, and altitude information of the high-speed mobile platform at all times. Let be the radius of curvature in the east-west plane, 'a' represent the Earth's semi-major axis, approximately 6378136.49 meters, and sin(·) denote the sine operation. This represents a square root operation.

[0052] The speed information is: [v R,N (t m ),v R,E (t m ),v R,D (t m )], where t m Indicates location and time, v R,N (t m ),v R,E (t m ) and v R,D (t m ) represent t respectively m The instantaneous velocity vectors of the high dynamic range receiving platform along the due north direction, the due east direction, and the vertically downward direction.

[0053] The high dynamic receiving platform position error calculation module 230 is used to: calculate the position error information of the motion platform in the geocentric coordinate system based on the position information and velocity information of the motion platform, and correct the position information of the motion platform based on the position error information to obtain the corrected position and attitude information of the motion platform in the geocentric coordinate system.

[0054] Among them, the position error information of the motion platform in the geocentric-fixed coordinate system includes the error Δx(t) of the motion platform along the straight-line direction in the geocentric-fixed coordinate system. m The error Δy(t) of the motion platform along the vertical flight path in the geocentric coordinate system. m The error Δz(t) of the motion platform along the vertical flight path in the geocentric coordinate system. m );

[0055]

[0056]

[0057]

[0058] Where α is the angle between the high dynamic range receiving platform and true north. This indicates the integration operation. This indicates an averaging operation.

[0059] The one-dimensional range image processing module 240 is used to: sequentially perform range-direction pulse compression, motion correction and phase compensation on the echo signal of the scene of interest to obtain a one-dimensional range image imaging result;

[0060] The motion platform also includes a compensation factor construction module;

[0061] The compensation factor construction module is used to obtain the distance travel correction factor and the phase compensation factor based on the position error information of the motion platform in the geocentric coordinate system.

[0062] The one-dimensional range image processing module 240 is specifically used to: sequentially perform range-direction pulse compression, movement correction based on movement correction factor, and phase compensation based on phase compensation factor on the echo signal of the scene of interest, so as to obtain the one-dimensional range image imaging result.

[0063] The process for calculating the distance travel correction factor and the phase compensation factor is as follows:

[0064] Calculate the motion error Δr(t) along the beamline direction caused by the non-ideal motion of the high dynamic range receiving platform. m ): Δr(t m )=Δz(t m cosβ(t) m )+Δy(t m sinβ(t) m ), where β(t) m () indicates the instantaneous downward perspective. H(t m H(t) represents the instantaneous altitude of the high dynamic range receiving platform. m )=z R (t m )+Δz(t m ), R s (t m () represents the instantaneous distance between the high dynamic range receiving platform and the scene center. (x0,y0,z0) represents the x-coordinate, y-coordinate, and z-coordinate of the center point of the scene.

[0065] Construct a distance walking correction factor H1(f) corresponding to the non-ideal motion of the high dynamic receiving platform. r ,t m ),

[0066] Construct a phase error compensation factor H2(t,t) corresponding to the non-ideal motion of the high dynamic receiving platform. m ),

[0067] Where t is the fast time and λ is the radar wavelength.

[0068] The process of obtaining one-dimensional range image results is as follows:

[0069] Compared to the direct wave signal, the reflected signal is a superposition of the delay and phase of the pseudo-random sequence code (PRN). Range compression is performed using a reference signal, range travel correction factor is used for range travel correction, and phase error compensation factor is used for phase compensation. The specific implementation is as follows:

[0070] s(t) = IFFT[FFT[s r (t)](FFT[s ref (t)]) * ·H1(f r ,t m )]·H2(t,t m )

[0071] Where FFT(·) and IFFT(·) represent the Fourier transform and inverse transform, respectively; s(t) represents the range-directed compressed signal; s r (t) represents the echo signal; s ref (t) represents the reference signal; * indicates taking the conjugate, s ref (t)=C PRN (t)exp(j2πf c t);

[0072] The distance upsampling module 250 is used to: perform upsampling processing on the one-dimensional distance image imaging results to obtain refined upsampling results, specifically:

[0073] Distance upsampling can be achieved through interpolation, which can be categorized into frequency domain interpolation and time domain interpolation. Frequency domain interpolation can only obtain sampling points at certain specific intervals, making it less flexible. Here, we adopt a Sinc interpolation method that is not limited by the sampling interval. The formula for calculating the Sinc interpolation coefficients is as follows:

[0074]

[0075] Where sin(·) represents the sine operation, and the Sinc interpolation formula for any point t is:

[0076]

[0077] In the formula s g (n) represents the distance pulse pressure signal, therefore when t = n, s g (n) = s(t). From the interpolation formula, it can be seen that the value s(t) at the interpolation point t is equal to the value of the sample s within the interpolation kernel. g The sum of the products of (n) and the interpolation kernel sinc(tn).

[0078] The mesh division module 260 is used to: divide the imaging area corresponding to the scene of interest into multiple mesh units according to the resolution and imaging longitude and latitude index requirements; specifically:

[0079] Convert the longitude and latitude information I, II, III, IV of the four corners of the imaging area in the geodetic coordinate system to the ECEF coordinate system as follows:

[0080] The longitude and latitude information of the four corners of the geodetic coordinate system I(B I ,L I ,H I ),II(B II ,L II ,H II ),IV(B III ,L III ,H III ),D(B IV ,L IV ,H IV ) is converted to the ECEF coordinate system as: I(X I ,Y I ,Z I ),II(X II ,Y II ,Z II ),IV(X III ,Y III ,Z III ),D(X IV ,Y IV ,Z IV ). The specific conversion formula is as follows:

[0081]

[0082] where e is the eccentricity of the earth (B k ,L k ,H k ) respectively represent the latitude, longitude and altitude values of the kth point, k = I, II, III, IV, is the radius of curvature in the prime vertical plane.

[0083] Assume that the imaging resolution is set to (δx, δy, δz), then the number of mesh points divided along the X-axis, Y-axis and Z-axis are respectively

[0084]

[0085]

[0086]

[0087] where X min =min(X I ,XII ,X III ,X IV ), X max =max(X I ,X II ,X III ,X IV )

[0088] Y min =min(Y) I ,Y II ,Y III ,Y IV ), Y max =max(Y I ,Y II ,Y III ,Y IV ).

[0089] The back-projection 2D imaging module 270 is used to: calculate the delay component of any grid cell based on the attitude information of GPS satellites and the corrected position and attitude information of the motion platform; back-project the refined upsampling result according to the corresponding geographical location to obtain the high-resolution imaging result of that grid cell; and so on until the high-resolution imaging result of each grid cell is obtained. The high-resolution imaging results of each grid cell are then combined to obtain the bi-base 2D imaging result of the scene of interest. Specifically:

[0090] The instantaneous position information of the satellite platform is as follows:

[0091] [x T (t m ),y T (t m ),z T (t m )]

[0092] Corrected position and attitude information of high dynamic receiving platform

[0093] [x R (t m )+Δx(t m ),y R (t m )+Δy(t m ),z R (t m )+Δz(t m )]

[0094] Therefore, the distance between the satellite platform and any point P(x) in the scene can be calculated. i ,y j ,z k The instantaneous slant distance R T,i,j,k (t m )for

[0095]

[0096] Therefore, the instantaneous slant range R between the satellite platform and the scene can be calculated. R,i,j,k (t m )for

[0097]

[0098] At this point, we can further calculate the instantaneous bistatic slant distance history as follows:

[0099] R Bi (t m ) = R T,i,j,k (t m )+R R,i,j,k (t m )

[0100] Meanwhile, the instantaneous slant distance between the satellite platform and the receiving platform is

[0101]

[0102] Constructing phase compensation factors

[0103]

[0104] The result after bistatic imaging is

[0105]

[0106] Perform back-projection two-dimensional imaging processing on all grid cells until a bi-basic two-dimensional imaging result is obtained.

[0107] Alternatively, in the above technical solutions, the motion platform can be a helicopter, a civil airliner, a fighter jet, or a missile.

[0108] The purpose of this invention is to propose a bistatic imaging method for an external radiation source under a high dynamic range receiving platform. This method compensates for the non-ideal motion of the platform by constructing corresponding range axis travel correction factors and phase compensation factors. It achieves an accurate description of the high dynamic range receiving platform's position through compensation for the platform's motion attitude, and realizes high-resolution two-dimensional focusing processing of the region of interest through range interpolation and back projection. In other words, firstly, by compensating and correcting the motion platform's attitude, the position of the motion platform can be determined more accurately. Then, high-resolution two-dimensional focusing processing of the region of interest is achieved through back projection, resulting in a bistatic two-dimensional imaging result of the scene of interest, i.e., a bistatic two-dimensional graphic of the scene of interest.

[0109] It has the following beneficial effects:

[0110] 1) This invention creatively proposes a bistatic imaging method for external radiation sources under a high dynamic receiving platform. Through a series of refined motion compensation methods, bistatic imaging of external radiation sources under a high dynamic receiving platform can be realized.

[0111] 2) The method of the present invention does not require hardware modifications to existing radar equipment in its specific implementation, and has good prospects for engineering applications.

[0112] The advantages of this invention can be further illustrated by the following simulation experiments.

[0113] 1) Simulation experimental environment:

[0114] Experimental environment: MATLAB R2020a, Intel(R) Core i7-1165G7@2.8GHz, Windows 10 Ultimate.

[0115] 2) Simulation experiment content and result analysis:

[0116] Experimental content: Using GPS signals, the echo acquisition process under a high dynamic range receiving platform is simulated, and the present invention is applied for imaging in the simulation environment.

[0117] Bistatic imaging of a certain area was performed, and the results of bistatic imaging of an external radiation source under a high dynamic range receiving platform are as follows: Figures 2 to 7 As shown, specifically:

[0118] Figure 2 It is a scene with real pixel art; Figure 3 The results are imaging results of a binary target from a dot matrix external field radiation source using the traditional P-code method. Figure 4 This is the result of bistatic imaging of the target external field radiation source of the P-code dot matrix of the present invention; Figure 5 The scene depicts a car outline composed of dot matrix objects. Figure 6 This is a bistatic imaging result of an external field radiation source of a surface target using the traditional P-code method; Figure 7 This is the bistatic imaging result of the external field radiation source of the P-code plane target in this invention, specifically: 1) from Figures 2-4 It can be seen that, for point targets, traditional methods exhibit significant defocusing when performing bistatic imaging, while the bistatic imaging results of the present invention are clearer and the defocusing phenomenon is eliminated. This demonstrates that the method of the present invention can be applied to bistatic imaging of external radiation sources under high dynamic range receiving platforms.

[0119] 2) From Figures 5-7 It can be seen that, for surface targets, traditional methods exhibit significant defocusing when performing bistatic imaging, while the bistatic imaging results of the present invention have clearer contours and eliminate defocusing. This demonstrates that the method of the present invention can be applied to bistatic imaging of external radiation sources under high dynamic range receiving platforms.

[0120] like Figure 8 As shown, an embodiment of the present invention provides a method for bistatic imaging of an external radiation source under a motion platform, employing the aforementioned bistatic imaging system for an external radiation source under a motion platform. The method includes:

[0121] S1. The GPS signal receiving module 210 receives the direct wave signal from the GPS satellite and the echo signal from the scene of interest, and calculates the attitude information of the GPS satellite based on the direct wave signal from the GPS satellite.

[0122] S2, The high dynamic range receiving platform attitude measurement module 220 acquires the position and velocity information of the motion platform;

[0123] S3. The high dynamic receiving platform position error calculation module 230 calculates the position error information of the motion platform in the geocentric coordinate system based on the position information and velocity information of the motion platform, and corrects the position information of the motion platform based on the position error information to obtain the corrected position and attitude information of the motion platform in the geocentric coordinate system.

[0124] S4. The one-dimensional range image processing module 240 sequentially performs range-direction pulse compression, motion correction, and phase compensation on the echo signal of the scene of interest to obtain the one-dimensional range image imaging result.

[0125] S5, the distance upsampling module 250 performs upsampling processing on the one-dimensional distance image imaging results to obtain refined upsampling results;

[0126] S6. The grid division module 260 divides the imaging region corresponding to the scene of interest into multiple grid units according to the resolution and imaging latitude and longitude index requirements.

[0127] S7. The back-projection two-dimensional imaging module 270 calculates the delay component of any grid cell based on the attitude information of GPS satellites and the corrected position and attitude information of the motion platform, and back-projects the refined upsampling result according to the corresponding geographical location to obtain the high-resolution imaging result of the grid cell, until the high-resolution imaging result of each grid cell is obtained. The high-resolution imaging results of each grid cell are combined to obtain the bi-base two-dimensional imaging result of the scene of interest.

[0128] First, by compensating and correcting the attitude of the motion platform, the position of the motion platform can be determined more accurately. Then, by back projection, high-resolution two-dimensional focusing processing of the region of interest is achieved, resulting in a bi-base two-dimensional imaging result of the scene of interest, i.e., a bi-base two-dimensional graphic of the scene of interest.

[0129] Optionally, in the above technical solution, the motion platform further includes a compensation factor construction module, and the method further includes:

[0130] S04. The compensation factor construction module obtains the distance travel correction factor and the phase compensation factor based on the position error information of the motion platform in the geocentric coordinate system.

[0131] In S4, the process by which the one-dimensional range image processing module 240 obtains the one-dimensional range image imaging result includes:

[0132] S40 and the one-dimensional range image processing module 240 sequentially perform range pulse compression, movement correction based on movement correction factor, and phase compensation based on phase compensation factor on the echo signal of the scene of interest to obtain the one-dimensional range image imaging result.

[0133] Optionally, in the above technical solution, the GPS signal receiving module 210 includes a right-hand circularly polarized antenna and a left-hand circularly polarized antenna. The right-hand circularly polarized antenna is used to receive the direct wave signal from GPS satellites, and the left-hand circularly polarized antenna is used to receive the echo signal from the scene of interest.

[0134] Optionally, in the above technical solution, the position error information of the motion platform in the geocentric-ground-fixed coordinate system includes: the error of the motion platform along the straight-line direction in the geocentric-ground-fixed coordinate system, the error of the motion platform along the vertical-line direction in the geocentric-ground-fixed coordinate system, and the error of the motion platform along the vertical-line direction in the geocentric-ground-fixed coordinate system.

[0135] Optionally, in the above technical solutions, the motion platform can be a drone, helicopter, civil airliner, fighter jet, missile, etc.

[0136] In the above embodiments, although the steps are numbered S1, S2, etc., they are only specific embodiments given in this application. Those skilled in the art can adjust the execution order of S1, S2, etc. according to the actual situation, which is also within the protection scope of this invention. It can be understood that in some embodiments, some or all of the above embodiments may be included.

[0137] The implementation of each step in the above-described method for bistatic imaging of an external radiation source under a motion platform according to the present invention can be referred to the above-described embodiment of a bistatic imaging system for an external radiation source under a motion platform, and will not be repeated here.

[0138] Those skilled in the art will know that this invention can be implemented as a system, method, or computer program product.

[0139] Therefore, this disclosure can be implemented in the following forms: it can be entirely hardware, entirely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software, generally referred to herein as a "circuit," "module," or "system." Furthermore, in some embodiments, the invention can also be implemented as a computer program product in one or more computer-readable media, the computer-readable medium containing computer-readable program code.

[0140] Any combination of one or more computer-readable media may be used. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. A computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this document, a computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in connection with an instruction execution system, apparatus, or device.

[0141] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A dual-base imaging system with an external radiation source under a motion platform, characterized in that, The motion platform includes a GPS signal receiving module, a high dynamic range receiving platform attitude measurement module, a high dynamic range receiving platform position error calculation module, a one-dimensional range image processing module, a range upsampling module, a mesh generation module, and a back projection two-dimensional imaging module. The GPS signal receiving module is used to: receive the direct wave signal from the GPS satellite and the echo signal from the scene of interest, and calculate the attitude information of the GPS satellite based on the direct wave signal from the GPS satellite; The high dynamic receiving platform attitude measurement module is used to: acquire the position information and velocity information of the motion platform; The high dynamic receiving platform position error calculation module is used to: calculate the position error information of the motion platform in the geocentric coordinate system based on the position information and velocity information of the motion platform, and correct the position information of the motion platform based on the position error information to obtain the corrected position and attitude information of the motion platform in the geocentric coordinate system. The one-dimensional range image processing module is used to: sequentially perform range-direction pulse compression, motion correction, and phase compensation on the echo signal of the scene of interest to obtain a one-dimensional range image imaging result; The distance upsampling module is used to: perform upsampling processing on the one-dimensional distance image imaging result to obtain a refined upsampling result; The grid division module is used to: divide the imaging region corresponding to the scene of interest into grids according to the resolution and imaging latitude and longitude index requirements, so as to obtain multiple grid units; The back-projection two-dimensional imaging module is used to: calculate the delay component of any grid cell based on the attitude information of the GPS satellite and the corrected position and attitude information of the motion platform, and back-project the refined upsampling result according to the corresponding geographical location to obtain the high-resolution imaging result of the grid cell, until the high-resolution imaging result of each grid cell is obtained, and combine the high-resolution imaging results of each grid cell to obtain the bi-base two-dimensional imaging result of the scene of interest.

2. The dual-base imaging system with an external radiation source under a motion platform according to claim 1, characterized in that, The motion platform also includes a compensation factor construction module; The compensation factor construction module is used to: obtain the distance travel correction factor and the phase compensation factor based on the position error information of the motion platform in the geocentric coordinate system; The one-dimensional range image processing module is specifically used to: sequentially perform range-direction pulse compression, movement correction based on the movement correction factor, and phase compensation based on the phase compensation factor on the echo signal of the scene of interest, to obtain a one-dimensional range image imaging result.

3. The dual-base imaging system with an external radiation source under a motion platform according to claim 1, characterized in that, The GPS signal receiving module includes a right-hand circularly polarized antenna and a left-hand circularly polarized antenna. The right-hand circularly polarized antenna is used to receive the direct wave signal from the GPS satellite, and the left-hand circularly polarized antenna is used to receive the echo signal from the scene of interest.

4. A dual-base imaging system for an external radiation source under a motion platform according to any one of claims 1 to 3, characterized in that, The position error information of the motion platform in the geocentric-ground-fixed coordinate system includes: the error of the motion platform along the straight line direction in the geocentric-ground-fixed coordinate system, the error of the motion platform along the vertical line direction in the geocentric-ground-fixed coordinate system, and the error of the motion platform along the vertical line direction in the geocentric-ground-fixed coordinate system.

5. A dual-base imaging system for an external radiation source under a motion platform according to any one of claims 1 to 3, characterized in that, The motion platform can be a drone, helicopter, commercial airliner, fighter jet, or missile.

6. A method for bistatic imaging of an external radiation source under a motion platform, characterized in that, The method of using the external radiation source bistatic imaging system under a motion platform as described in claim 1 includes: The GPS signal receiving module receives the direct wave signal from the GPS satellite and the echo signal from the scene of interest, and calculates the attitude information of the GPS satellite based on the direct wave signal from the GPS satellite. The high dynamic receiving platform attitude measurement module acquires the position and velocity information of the motion platform; The high dynamic receiving platform position error calculation module calculates the position error information of the motion platform in the geocentric coordinate system based on the position information and velocity information of the motion platform, and corrects the position information of the motion platform based on the position error information to obtain the corrected position and attitude information of the motion platform in the geocentric coordinate system. The one-dimensional range image processing module sequentially performs range-direction pulse compression, motion correction, and phase compensation on the echo signal of the scene of interest to obtain a one-dimensional range image imaging result. The distance upsampling module performs upsampling processing on the one-dimensional distance image imaging result to obtain a refined upsampling result; The grid division module divides the imaging region corresponding to the scene of interest into multiple grid units according to the resolution and imaging latitude and longitude index requirements. The back-projection two-dimensional imaging module calculates the delay component of any grid cell based on the attitude information of the GPS satellite and the corrected position and attitude information of the motion platform, and back-projects the refined upsampling result according to the corresponding geographical location to obtain the high-resolution imaging result of the grid cell, until the high-resolution imaging result of each grid cell is obtained. The high-resolution imaging results of each grid cell are combined to obtain the bi-base two-dimensional imaging result of the scene of interest.

7. The method for bistatic imaging of an external radiation source under a motion platform according to claim 6, characterized in that, The motion platform also includes a compensation factor construction module, and the method further includes: The compensation factor construction module obtains the distance travel correction factor and the phase compensation factor based on the position error information of the motion platform in the geocentric coordinate system. The process by which the one-dimensional range image processing module obtains the one-dimensional range image imaging result includes: The one-dimensional range image processing module sequentially performs range-direction pulse compression, movement correction based on the movement correction factor, and phase compensation based on the phase compensation factor on the echo signal of the scene of interest to obtain a one-dimensional range image imaging result.

8. The method for bistatic imaging of an external radiation source under a motion platform according to claim 6, characterized in that, The GPS signal receiving module includes a right-hand circularly polarized antenna and a left-hand circularly polarized antenna. The right-hand circularly polarized antenna is used to receive the direct wave signal from the GPS satellite, and the left-hand circularly polarized antenna is used to receive the echo signal from the scene of interest.

9. A bistatic imaging method for an external radiation source under a motion platform according to any one of claims 6 to 8, characterized in that, The position error information of the motion platform in the geocentric-ground-fixed coordinate system includes: the error of the motion platform along the straight line direction in the geocentric-ground-fixed coordinate system, the error of the motion platform along the vertical line direction in the geocentric-ground-fixed coordinate system, and the error of the motion platform along the vertical line direction in the geocentric-ground-fixed coordinate system.

10. A bistatic imaging method for an external radiation source under a motion platform according to any one of claims 6 to 8, characterized in that, The motion platform can be a drone, helicopter, commercial airliner, fighter jet, or missile.

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