External radiation source bistatic imaging system and method under high dynamic receiving platform

Abstract

The application relates to the technical field of bistatic radar imaging technology, in particular to an external radiation source bistatic imaging system and method under a high dynamic receiving platform. The system comprises a high dynamic receiving platform with a GPS signal receiving module, a high dynamic receiving platform attitude 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. First, the position of the high dynamic receiving platform can be determined more accurately through compensation and correction of the attitude of the high dynamic receiving 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] The present application relates to the technical field of bistatic radar imaging technology, and particularly relates to an external radiation source bistatic imaging system and method under a high dynamic receiving platform. BACKGROUND

[0002] Global Navigation Satellite System-Reflectometry (GNSS-R) technology is a new branch of GNSS field gradually developed since the 1990s, and remote sensing of the earth can be realized through processing of reflected signals. Commonly used GNSS signals include GPS signals of the United States, Beidou signals of China, Galileo signals of Europe and GLONAS of Russia.

[0003] The GNSS-R system fully utilizes the global coverage advantage of navigation satellites, has the low power consumption advantage of external radiation source radar, and has the advantages of high deployment orbit and wide coverage, and can effectively solve the problems of insufficient coverage range of ground-based radar system and low-altitude blind area caused by earth curvature, and can realize large-scale detection and imaging of the earth.

[0004] In the aspect of GNSS-R imaging of the earth, the University of Birmingham Microwave Integrated Systems Laboratory in the United Kingdom carried out a bistatic imaging experiment of ground fixed receiver and vehicle-mounted receiver scene using GLONAS signals and Galileo signals as external radiation sources in 2012. Beijing University of Technology analyzed the influence of ionosphere on GEO-SAR imaging, and carried out experimental verification by using point target simulation and GPS signals. In addition, Beijing University of Aeronautics and Astronautics, Xi'an University of Electronic Science and Technology and other units also carried out research on bistatic imaging in ground scene. GNSS-R technology not only does not occupy new frequency band resources, but also has the advantages of simple equipment, good flexibility and strong concealment, and has broad application prospects in the future remote sensing field.

[0005] At present, the research on external radiation source bistatic detection and imaging in China mainly focuses on ground scene (ground fixed receiving platform and vehicle-mounted receiving platform), and the research on airborne motion scene is less, especially the research on external radiation source bistatic imaging under high dynamic receiving platform is less. Due to the non-ideal motion of the high dynamic receiving platform, the transmission and reception slant range history of the radar echo signal changes, the traditional bistatic imaging method is invalid, and the imaging result is out of focus, so it is necessary to research the external radiation source bistatic imaging method under the high dynamic receiving platform. SUMMARY

[0006] The present application solves the technical problems of the prior art, and provides an external radiation source bistatic imaging system and method under a high dynamic receiving platform.

[0007] The technical scheme of the external radiation source double-baseline imaging system under the high dynamic receiving platform of the application is as follows:

[0008] The high dynamic receiving platform comprises a GPS signal receiving module, a high dynamic receiving platform attitude measurement module, a high dynamic receiving platform position error calculation module, a one-dimensional range image processing module, a range upsampling module, a grid division module and a reverse projection two-dimensional imaging module.

[0009] The GPS signal receiving module is configured to receive direct wave signals of GPS satellites and echo signals of a scene of interest, and to calculate attitude information of the GPS satellites according to the direct wave signals of the GPS satellites.

[0010] The high dynamic receiving platform attitude measurement module is configured to obtain position information, velocity information and acceleration information of the high dynamic receiving platform.

[0011] The high dynamic receiving platform position error calculation module is configured to calculate position error information of the high dynamic receiving platform in a geocentric geodetic coordinate system according to the position information, velocity information and acceleration information of the high dynamic receiving platform, and to correct the position information of the high dynamic receiving platform according to the position error information to obtain corrected position attitude information of the high dynamic receiving platform in the geocentric geodetic coordinate system.

[0012] The one-dimensional range image processing module is configured to sequentially perform range direction pulse compression, walk correction and phase compensation on the echo signals of the scene of interest to obtain one-dimensional range image imaging results.

[0013] The range upsampling module is configured to perform upsampling processing on the one-dimensional range image imaging results to obtain refined upsampling results.

[0014] The grid division module is configured to divide an imaging area corresponding to the scene of interest into a plurality of grid units according to resolution and imaging longitude and latitude index requirements.

[0015] The reverse projection two-dimensional imaging module is configured to calculate a delay component of any grid unit according to the attitude information of the GPS satellites and the corrected position attitude information of the high dynamic receiving platform, to perform reverse projection on the refined upsampling results according to a corresponding geographical position to obtain high-resolution imaging results of the grid unit, and to combine the high-resolution imaging results of each grid unit to obtain double-baseline two-dimensional imaging results of the scene of interest.

[0016] The external radiation source double-baseline imaging system under the high dynamic receiving platform of the application has the following beneficial effects:

[0017] Firstly, the position of the high dynamic receiving platform can be determined more accurately by compensating and correcting the attitude of the high dynamic receiving platform, and then high resolution two-dimensional focusing processing of the region of interest is realized by reverse projection to obtain the two-dimensional imaging result of the external radiation source dual base of the scene of interest, that is, the two-dimensional graph of the scene of interest.

[0018] The technical scheme of the external radiation source dual base imaging method under the high dynamic receiving platform of the application is as follows:

[0019] The external radiation source dual base imaging system under the high dynamic receiving platform adopts the method, and the method comprises the following steps:

[0020] The GPS signal receiving module receives the direct wave signal of the GPS satellite and the echo signal of the scene of interest, and calculates the attitude information of the GPS satellite according to the direct wave signal of the GPS satellite;

[0021] The high dynamic receiving platform attitude measurement module obtains the position information, speed information and acceleration information of the high dynamic receiving platform;

[0022] The high dynamic receiving platform position error calculation module calculates the position error information of the high dynamic receiving platform in the earth-fixed coordinate system according to the position information, speed information and acceleration information of the high dynamic receiving platform, and corrects the position information of the high dynamic receiving platform according to the position error information to obtain the corrected position attitude information of the high dynamic receiving platform in the earth-fixed coordinate system;

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

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

[0025] The grid division module divides the imaging area corresponding to the scene of interest into a plurality of grid units according to the resolution and imaging latitude and longitude index requirements;

[0026] The reverse projection two-dimensional imaging module calculates the delay component of any grid unit according to the attitude information of the GPS satellite and the corrected position attitude information of the high dynamic receiving platform, and performs reverse projection on the refined upsampling result according to the corresponding geographical position to obtain the high resolution imaging result of the grid unit, until the high resolution imaging result of each grid unit is obtained, and the high resolution imaging results of each grid unit are combined to obtain the two-dimensional imaging result of the scene of interest.

[0027] The high-dynamic-receiving-platform-underlying external radiation source binocular imaging method has the following beneficial effects:

[0028] Firstly, the position of the high-dynamic-receiving platform can be determined more accurately by compensating and correcting the attitude of the high-dynamic-receiving platform, and then the high-resolution two-dimensional focusing processing of the region of interest is realized by reverse projection to obtain the binocular two-dimensional imaging result of the scene of interest, i.e., the binocular two-dimensional image of the scene of interest. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 FIG. 1 is a structural schematic diagram of an external radiation source binocular imaging system under a high-dynamic-receiving platform according to an embodiment of the present application;

[0030] Figure 2 is the binocular imaging result of a dot matrix external field radiation source target by using the traditional method of C / A code;

[0031] Figure 3 is the binocular imaging result of a dot matrix external field radiation source target by using the traditional method of C / A code;

[0032] Figure 4 is the binocular imaging result of a dot matrix external field radiation source target by using the traditional method of P code;

[0033] Figure 5 is the binocular imaging result of a dot matrix external field radiation source target by using the traditional method of P code;

[0034] Figure 6 is the binocular imaging result of a surface target external field radiation source by using the traditional method of C / A code;

[0035] Figure 7 is the binocular imaging result of a surface target external field radiation source by using the traditional method of C / A code;

[0036] Figure 8 is the binocular imaging result of a surface target external field radiation source by using the traditional method of P code;

[0037] Figure 9 is the binocular imaging result of a surface target external field radiation source by using the traditional method of P code.

[0038] Figure 10 FIG. 2 is a flowchart of an external radiation source binocular imaging method under a high-dynamic-receiving platform according to an embodiment of the present application. DETAILED DESCRIPTION

[0039] As Figure 1As shown, the high-dynamic receiving platform under the external radiation source double-basis imaging system of the embodiment of the application comprises a high-dynamic receiving 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 grid division module 260, and a reverse projection two-dimensional imaging module 270.

[0040] The GPS signal receiving module 210 is configured to receive a direct wave signal of a GPS satellite and an echo signal of a scene of interest, and to calculate attitude information of the GPS satellite according to the direct wave signal of the GPS satellite.

[0041] The GPS signal receiving module 210 comprises a right-hand circularly polarized antenna and a left-hand circularly polarized antenna, the right-hand circularly polarized antenna is configured to receive the direct wave signal of the GPS satellite, and the left-hand circularly polarized antenna is configured to receive the echo signal of the scene of interest.

[0042] The direct wave signal s d (t-τ d ) of the GPS satellite is as follows:

[0043] s d (t-τ d ) = C PRN (t-τ d )D(t-τ d )exp[j2πf c (t-τ d )]

[0044] Wherein, t represents fast time, τ d represents time delay of the direct wave signal, C PRN (t-τ d ) represents a pseudo-random sequence code (PRN) corresponding to t-τ d , mainly including C / A code and P code, D(t-τ d ) represents D code data code corresponding to t-τ d , the code rate of the D code data code is usually 50 Hz, the D code data code is modulated on the corresponding carrier through binary phase shift keying (BPSK), f c represents carrier frequency of the direct wave signal, j represents a symbol of imaginary part, and 2πf c (t-τ d ) represents phase of t-τ d .

[0045] The echo signal s r (t) of the scene of interest is as follows:

[0046] s r (t) = C PRN(t-τ r )D(t-τ r )exp[j2πf c (t-τ r )]

[0047] =C PRN (t-τ r )D(t-τ r )exp(j2πf c t)exp(-j2πf c τ r )

[0048] According to the data code of the GPS satellite and the direct wave signal of the GPS satellite, the attitude information of the GPS satellite is calculated as: [x T (t m ),y T (t m ),z T (t m )], wherein τ r represents the time transmitted from the satellite to the target and then from the target to the receiver, t-τ r represents the fast time after the delay τ r , C PRN (t-τ r ) and D(t-τ r ) represent the pseudo-random code signal and the data code signal of t-τ r respectively. t m represents the azimuth slow time, x T (t m ), y T (t m ) and z T (t m ) represent the instantaneous abscissa, the instantaneous ordinate and the instantaneous ordinate of the GPS satellite at t m .

[0049] The high-dynamic receiving platform attitude measurement module 220 is configured to acquire position information and velocity information of the high-dynamic receiving platform, and specifically:

[0050] The position information is: [x R (t m ),y R (t m ),z R (t m )], wherein t m represents the azimuth slow time, x R (t m ), y R (t m ) and zR (t m ) respectively represent the instantaneous abscissa, the instantaneous ordinate and the instantaneous ordinate of the high-dynamic receiving platform at time t m .

[0051] Since the position data recorded by the inertial measurement unit is longitude, latitude and height information in geodetic coordinates, it is necessary to convert the position information of the high-dynamic receiving platform to abscissa, ordinate and ordinate information in the ECEF coordinate system. The conversion formula is as follows:

[0052]

[0053] where e is the eccentricity of the earth (B(t m ), L(t m ), H(t m )) respectively represent the latitude, longitude and height value information of the high-speed maneuvering platform at time t m , is the radius of curvature in the equinoctial plane a represents the long semi-axis of the earth, which is about 6378136.49 meters, and sin(·) represents the sine operation, represents the square root operation.

[0054] where the velocity information is: [v R,N (t m ), v R,E (t m ), v R,D (t m )], where t m represents the azimuth slow time, v R,N (t m ), v R,E (t m ) and v R,D (t m ) respectively represent the instantaneous velocity vector of the high-dynamic receiving platform in the north direction, the instantaneous velocity vector in the east direction and the instantaneous velocity vector in the vertical downward direction at time t m .

[0055] where the acceleration information of the high-dynamic receiving platform includes the instantaneous acceleration vector of the high-dynamic receiving platform in the north direction at the current time, the instantaneous acceleration vector in the east direction and the instantaneous acceleration vector in the vertical downward direction, specifically:

[0056] The acceleration information of the high-dynamic receiving platform is [a R,N (t m ), a R,E (t m ), a R,D (t m )], where t mazimuthal slow time, a R,N (t m ) denotes: the high-dynamic receiving platform at the current time t m instantaneous acceleration vector along the positive north direction, a R,E (t m ) denotes: the high-dynamic receiving platform at the current time t m instantaneous acceleration vector along the positive east direction, a R,D (t m ) denotes: the high-dynamic receiving platform at the current time t m instantaneous acceleration vector along the vertical downward direction.

[0057] The high-dynamic receiving platform position error calculation module 230 is configured to: calculate position error information of the high-dynamic receiving platform in the Earth-Centered Earth-Fixed coordinate system according to position information, velocity information and acceleration information of the high-dynamic receiving platform, and correct the position information of the high-dynamic receiving platform according to the position error information to obtain corrected position and attitude information of the high-dynamic receiving platform in the Earth-Centered Earth-Fixed coordinate system;

[0058] The position error information of the high-dynamic receiving platform in the Earth-Centered Earth-Fixed coordinate system includes an error Δx(t m ) of the high-dynamic receiving platform in the Earth-Centered Earth-Fixed coordinate system along the direct line direction, an error Δy(t m ) of the high-dynamic receiving platform in the Earth-Centered Earth-Fixed coordinate system along the vertical line direction, and an error Δz(t m ) of the high-dynamic receiving platform in the Earth-Centered Earth-Fixed coordinate system along the vertical line direction.

[0059]

[0060]

[0061]

[0062] wherein α is an angle between the high-dynamic receiving platform and the positive north direction, denotes an integration operation, denotes an averaging operation.

[0063] The one-dimensional range image processing module 240 is configured to sequentially perform range direction pulse compression, walk correction and phase compensation on echo signals of a scene of interest to obtain one-dimensional range image imaging results.

[0064] The high-dynamic receiving platform further comprises a compensation factor construction module.

[0065] The compensation factor construction module is configured to obtain a range walk correction factor and a phase compensation factor according to the position error information of the high-dynamic receiving platform in the Earth-Centered Earth-Fixed coordinate system.

[0066] The one-dimensional range image processing module 240 is specifically configured to sequentially perform range direction pulse compression, walk correction based on a walk correction factor, and phase compensation based on a phase compensation factor on echo signals of a scene of interest, to obtain one-dimensional range image imaging results.

[0067] The process of calculating the range walk correction factor and the phase compensation factor is as follows:

[0068] The motion error Δr(t m ) along the beam sight direction caused by the non-ideal motion of the high-dynamic receiving platform is calculated as follows: m ) = Δz(t m )cosβ(t m ) + Δy(t m )sinβ(t m ), where β(t m ) represents an instantaneous downward angle, H(t m ) represents an instantaneous height of the high-dynamic receiving platform, H(t m ) = z R (t m ) + Δz(t m ), and R s (t m ) represents an instantaneous distance between the high-dynamic receiving platform and the scene center,

[0069] (x0, y0, z0) represents the horizontal coordinate, the vertical coordinate, and the vertical coordinate of the scene center point.

[0070] The range walk correction factor H1(f r , t m ) corresponding to the non-ideal motion of the high-dynamic receiving platform is constructed,

[0071] The phase error compensation factor H2(t, t m ) corresponding to the non-ideal motion of the high-dynamic receiving platform is constructed,

[0072] where t is the fast time, and λ is the radar wavelength.

[0073] The process of obtaining the one-dimensional range image imaging results is as follows:

[0074] Compared with the direct wave signal, the reflected signal is represented as a superposition of the delay and phase of the pseudo-random sequence code PRN. The reference signal is used for range compression, the range walk correction factor is used for range walk correction, and the phase error compensation factor is used for phase compensation. The specific implementation manner is as follows:

[0075] s(t) = IFFT[FFT[s r (t)]·(FFT[s ref (t)]) * ·H1(f r ,t m )]·H2(t,t m )

[0076] 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);

[0077] 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:

[0078] 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:

[0079]

[0080] The Sinc interpolation formula for any point t is:

[0081]

[0082] 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).

[0083] The mesh generation module 260 is used to: divide the imaging region corresponding to the scene of interest into multiple mesh units according to the resolution and imaging latitude and longitude requirements; specifically:

[0084] Based on the latitude and longitude information (I, II, III, IV) of the four corners of the geodetic coordinate system of the imaging area, the ECEF coordinate system is transformed as follows:

[0085] Geodetic coordinate system four-corner latitude and longitude information I(B) IL I ,H I ),II(B II ,L II ,H II ),IV(B III ,L III ,H III ),D(B IV ,L IV ,H IV ) are converted into 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:

[0086]

[0087] wherein e is the eccentricity of the earth (B k ,L k ,H k ) respectively represent the latitude, longitude and height value of the kth point, k = I, II, III, IV, is the radius of curvature in the equatorial plane.

[0088] Assuming that the imaging resolution is set as (δx, δy, δz), then the grid point number N x divided along the X axis, the grid point number N y divided along the Y axis and the grid point number N z divided along the Z axis are respectively

[0089]

[0090]

[0091]

[0092] wherein X min = min(X I , X II , X III , X IV ), X max = max(X I , X II , X III , X IV )

[0093] Y min = min(Y I , Y II , Y III , Y IV ), Y max = max(Y I , Y II , Y III , Y IV ).

[0094] The back-projection two-dimensional imaging module 270 is configured to: according to the attitude information of the GPS satellite and the corrected position attitude information of the high-dynamic receiving platform, calculate a delay component of any grid unit, and perform back-projection on the refined up-sampling result according to a corresponding geographical position to obtain a high-resolution imaging result of the grid unit, until a high-resolution imaging result of each grid unit is obtained, combine the high-resolution imaging result of each grid unit to obtain a two-dimensional imaging result of the scene of interest. Specifically:

[0095] The instantaneous position information of the satellite platform is:

[0096] [x T (t m ), y T (t m ), z T (t m )]

[0097] The corrected position attitude information of the high-dynamic receiving platform

[0098] [x R (t m )+Δx(t m ), y R (t m )+Δy(t m ), z R (t m )+Δz(t m )]

[0099] Therefore, the instantaneous slant range R T,i,j,k (t m ) between the satellite platform and any point P(x i , y j , z k ) in the scene can be calculated as

[0100]

[0101] Therefore, the instantaneous slant range R R,i,j,k (t m ) between the satellite platform and the scene can be calculated as:

[0102]

[0103] At this time, we can further obtain the instantaneous double-base slant range history as follows:

[0104] R Bi (t m )=R T,i,j,k (t m )+R R,i,j,k (t m )

[0105] At the same time, the instantaneous slant range between the satellite platform and the receiving platform is

[0106]

[0107] The phase compensation factor is constructed as follows:

[0108]

[0109] The result of double-base imaging is as follows:

[0110]

[0111] The reverse projection two-dimensional imaging processing is performed on all grid units until the double-base two-dimensional imaging result is obtained.

[0112] Optionally, in the above technical solution, the high dynamic receiving platform is a drone, a helicopter, a civil aviation passenger plane, a fighter or a missile.

[0113] The purpose of the present application is to provide a high dynamic receiving platform under the external radiation source double-base imaging method, which compensates for the non-ideal motion of the carrier platform by constructing the corresponding distance axis walking correction factor and the phase compensation factor, realizes the accurate description of the high dynamic receiving platform position by compensating for the platform motion attitude, realizes the high resolution two-dimensional focusing processing of the region of interest through distance interpolation and reverse projection. That is, first, the position of the high dynamic receiving platform can be more accurately determined by compensating for the attitude of the high dynamic receiving platform, and then the high resolution two-dimensional focusing processing of the region of interest is realized through reverse projection to obtain the double-base two-dimensional imaging result of the scene of interest, that is, the double-base two-dimensional image of the scene of interest. Has the following beneficial effects:

[0114] 1) The present application creatively proposes a high dynamic receiving platform under the external radiation source double-base imaging method, which can realize the external field radiation source double-base imaging under the high dynamic receiving platform through a series of fine motion compensation methods.

[0115] 2) The method of the present application does not need to improve the hardware of the existing radar equipment when it is implemented, and has good engineering application prospect.

[0116] The advantages of this invention can be further illustrated by the following simulation experiments.

[0117] 1) Simulation experimental environment:

[0118] Experimental environment: MATLAB R2020a, Intel(R) Core i7-1165G7@2.8GHz, Windows 10 Ultimate.

[0119] 2) Simulation experiment content and result analysis:

[0120] 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.

[0121] 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 9 As shown, specifically:

[0122] Figure 2 This is a bistatic imaging result of the external field radiation source of a dotted target using the traditional C / A code method. Figure 3 This is the result of bistatic imaging of the external field radiation source of the C / A code dot matrix target in this invention; Figure 4 This is the imaging result of a binary target from a dotted external field radiation source using the traditional P-code method. Figure 5 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 6 This is a bistatic imaging result of an external field radiation source for a surface target using the traditional C / A code method. Figure 7 This is the result of bistatic imaging of the external field radiation source of the C / A code plane target in this invention; Figure 8 This is a bistatic imaging result of an external field radiation source for a surface target using the traditional P-code method. Figure 9 This is the bistatic imaging result of the external field radiation source of the P-code plane target in this invention. 1) From Figures 2 to 5 It can be seen that, for point target scenarios, when the high dynamic platform is under acceleration, traditional methods exhibit significant defocusing when performing bistatic imaging on them. However, 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 receiving platforms.

[0123] 2) From Figures 6 to 9 As can be seen, when a high-dynamic platform experiences acceleration in a scene involving surface targets, traditional methods exhibit significant defocusing during bistatic imaging. However, the bistatic imaging results of this invention show clearer contours and eliminate defocusing, thus demonstrating that the method of this invention can be applied to bistatic imaging of external radiation sources under a high-dynamic receiving platform.

[0124] likeFigure 10 As shown, an embodiment of the present invention provides a bistatic imaging method for external radiation sources under a high dynamic range receiving platform. The method employs the aforementioned bistatic imaging system for external radiation sources under a high dynamic range receiving platform and includes:

[0125] 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.

[0126] S2, The attitude measurement module 220 of the high dynamic receiving platform acquires the position information, velocity information and acceleration information of the high dynamic receiving platform;

[0127] S3. The high dynamic receiving platform position error calculation module 230 calculates the position error information of the high dynamic receiving platform in the geocentric-ground-fixed coordinate system based on the position information, velocity information and acceleration information of the high dynamic receiving platform, and corrects the position information of the high dynamic receiving platform based on the position error information to obtain the corrected position and attitude information of the high dynamic receiving platform in the geocentric-ground-fixed coordinate system.

[0128] 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.

[0129] S5, the distance upsampling module 250 performs upsampling processing on the one-dimensional distance image imaging results to obtain refined upsampling results;

[0130] 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.

[0131] 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 high dynamic receiving 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.

[0132] First, by compensating and correcting the attitude of the high dynamic range receiving platform, the position of the high dynamic range receiving platform can be determined more accurately. Then, by back projection, high-resolution two-dimensional focusing processing of the region of interest is achieved, and the bi-base two-dimensional imaging result of the scene of interest, i.e., the bi-base two-dimensional graphic of the scene of interest, is obtained.

[0133] Optionally, in the above technical solution, the high dynamic range receiving platform further includes a compensation factor construction module, and the method further includes:

[0134] 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 high dynamic receiving platform in the geocentric coordinate system.

[0135] In S4, the process by which the one-dimensional range image processing module 240 obtains the one-dimensional range image imaging result includes:

[0136] 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.

[0137] 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.

[0138] Optionally, in the above technical solution, the acceleration information of the high dynamic receiving platform includes: the instantaneous acceleration vector of the high dynamic receiving platform at the current moment along the due north direction, the instantaneous acceleration vector along the due east direction, and the instantaneous acceleration vector along the vertically downward direction.

[0139] Optionally, in the above technical solutions, the high dynamic receiving platform can be a drone, helicopter, civil airliner, fighter jet, or missile.

[0140] 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.

[0141] The implementation of each step in the above-described method for bistatic imaging of an external radiation source under a high dynamic receiving platform of the present invention can be referred to the above-described embodiment of a bistatic imaging system for an external radiation source under a high dynamic receiving platform, and will not be repeated here.

[0142] Those skilled in the art will know that this invention can be implemented as a system, method, or computer program product.

[0143] 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.

[0144] 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.

[0145] 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 for an external radiation source under a high dynamic range receiving platform, characterized in that, The high dynamic range receiving 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 grid 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 attitude measurement module of the high dynamic receiving platform is used to: acquire the position information, velocity information and acceleration information of the high dynamic receiving platform; The high dynamic receiving platform position error calculation module is used to: calculate the position error information of the high dynamic receiving platform in the geocentric-ground-fixed coordinate system based on the position information, velocity information and acceleration information of the high dynamic receiving platform, and correct the position information of the high dynamic receiving platform based on the position error information to obtain the corrected position and attitude information of the high dynamic receiving platform in the geocentric-ground-fixed 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 attitude information of the high dynamic receiving 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 for an external radiation source under a high dynamic receiving platform according to claim 1, characterized in that, The high dynamic range receiving 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 high dynamic receiving 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 for an external radiation source under a high dynamic receiving 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 high dynamic receiving platform according to any one of claims 1 to 3, characterized in that, The acceleration information of the high dynamic receiving platform includes: the instantaneous acceleration vector of the high dynamic receiving platform at the current moment along the due north direction, the instantaneous acceleration vector along the due east direction, and the instantaneous acceleration vector along the vertically downward direction.

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

6. A bistatic imaging method for an external radiation source under a high dynamic range receiving platform, characterized in that, The method of using the external radiation source bistatic imaging system under a high dynamic receiving 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 attitude measurement module of the high dynamic receiving platform acquires the position information, velocity information and acceleration information of the high dynamic receiving platform; The high dynamic receiving platform position error calculation module calculates the position error information of the high dynamic receiving platform in the geocentric-ground-fixed coordinate system based on the position information, velocity information and acceleration information of the high dynamic receiving platform, and corrects the position information of the high dynamic receiving platform based on the position error information to obtain the corrected position and attitude information of the high dynamic receiving platform in the geocentric-ground-fixed 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 high dynamic receiving 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 high dynamic range receiving platform according to claim 6, characterized in that, The high dynamic range receiving 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 high dynamic receiving 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 high dynamic range receiving 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 high dynamic range receiving platform according to any one of claims 6 to 8, characterized in that, The acceleration information of the high dynamic receiving platform includes: the instantaneous acceleration vector of the high dynamic receiving platform at the current moment along the due north direction, the instantaneous acceleration vector along the due east direction, and the instantaneous acceleration vector along the vertically downward direction.

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

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