CN102466799B - Method for simulating interference SAR (Synthetic Aperture Radar) echo data based on POS (Posture) motion data - Google Patents

Abstract

The invention discloses a method for simulating interference SAR (Synthetic Aperture Radar) echo data based on POS (Posture) motion data, relating to an information acquiring and processing technology. POS data contain position information and posture information of an airborne platform of synthetic aperture radar (SAR). By using the method, airborne interference SAR original echo simulation based on actual motion data is realized through establishing a transformational relation between a POS coordinate system and a target scene coordinate system and fusing the motion information of the airborne platform into interference synthetic aperture radar echo calculation. The method comprises the following steps of: firstly, calculating the coordinate of a double-antenna phase center under a scene coordinate system by utilizing coordinate transformation; secondly, generating a correlation complex backscattering coefficient pair on the basis of real SAR image data; and thirdly, introducing DEM (Digital Elevation Model) topographic information, calculating two paths of original echo data according to an echo signal model, imaging and interfering to obtain an SAR image and an interference fringe.

Description

Interference SAR echo data emulation mode based on the POS exercise data

Technical field

The present invention relates to the sensing and processing technical field, is a kind of based on POS (POSition﹠amp; Orientation System) the interference SAR data simulation method of exercise data.

Background technology

Interference synthetic aperture radar (SAR) data simulation is for the checking of SAR imaging algorithm, and the SAR image processes, interferes the research of the aspects such as disposal route to have great significance.Interference SAR echo data emulation technology can be divided into time domain approach and frequency domain method at present, the advantage of frequency domain method maximum is that computing velocity is fast, comparing shortcoming with Time-Domain algorithm is that motion error model is difficult to introduce, the phase calculation precision is lower, for the interference SAR echo simulation, therefore phase accuracy has determined the precision of the interference SAR measurement of higher degree, adopts the method for frequency domain normally not satisfy simulation requirements.

Consider in the interference SAR data simulation of kinematic error, method commonly used is that the idealized motion error model that will artificially set up is incorporated into during echo calculates at present, such as the single frequency sinusoidal model etc.Yet in reality, the carrier aircraft platform is subjected to the impact of various factors, and movement locus is complicated and changeable, and there is the movement locus skew of a plurality of frequencies usually in simply single-frequency shake of kinematic error.Therefore, artificially set up idealized motion error model and introduce, still can't realize the airborne interference SAR original echo emulation based on the actual motion data.

Summary of the invention

The objective of the invention is to solve problems of the prior art, a kind of interference SAR data simulation method based on the POS exercise data is provided, carrier aircraft position of platform and attitude information that movement measurement system is recorded are fused in the emulation of interference SAR echo data, are a kind of echo simulation methods based on the actual motion error information.

For achieving the above object, technical solution of the present invention is:

A kind of interference SAR echo data emulation mode based on the POS exercise data, it is by setting up the transformational relation of POS coordinate system and target scene coordinate system, the kinematic error of carrier aircraft platform is fused in the calculating of interference synthetic aperture radar (SAR) echo, to realize the airborne interference SAR original echo emulation based on the actual motion data; Comprise the following steps: the first step, utilize coordinate transform to calculate double antenna phase center coordinate under the scene coordinate system; Second step take true SAR view data as the basis, generates correlativity plural number backscattering coefficient pair; The 3rd step, introduce the DEM terrain information, calculate two-way original echo data according to echo signal model, obtain SAR image and interference fringe through imaging with interfering to process.

Described interference SAR echo data emulation mode based on the POS exercise data, its described first step is through three coordinate system rotation, and positional information and attitude information are incorporated in the calculating of antenna phase center coordinate, comprising:

A) actual the earth's core, the POS center rotating coordinate system coordinate conversion that comprises positional information is arrived the earth surface level coordinate system;

B) be transformed into the scene coordinate system from the earth surface level coordinate system again;

C) calculate antenna phase center at the platform coordinate system coordinate according to the carrier aircraft attitude information, it is transformed in the scene coordinate system again, obtain double antenna coordinate under the scene coordinate system, set up the space geometry relation of radar and target, thereby realized the introducing of positional information and attitude information kinematic error in echo calculates.

Described interference SAR echo data emulation mode based on the POS exercise data, its described second step is to utilize true SAR picture amplitude data, generates the plural backscattering coefficient pair of correlativity, comprises step:

A) with the SAR picture amplitude as main antenna backscattering coefficient amplitude, be created between [π π] and obey equally distributed random phase;

B) on the linear combination basis of main antenna backscattering coefficient real part and imaginary part, add the random number of an independent normal distribution, in order to control the correlativity between major-minor antenna backscattering coefficient, generate auxiliary antenna backscattering coefficient pair: real part and imaginary part.

Described interference SAR echo data emulation mode based on the POS exercise data, real part and the imaginary part of the auxiliary antenna backscattering coefficient of its described generation, step is as follows:

Get main antenna backscattering coefficient γ ₁Real part x ₁With imaginary part y ₁, x ₁y ₁Obeying average is 0, and variance is σ ²Normal distribution and separate; The real part of auxiliary antenna backscattering coefficient and imaginary part are:

x ₂＝a _xx ₁+b _xy ₁+c _xz

y ₂＝a _yx ₁+b _yy ₁

a _x＝(2ρ-1)cos(ψ _ρ)

b _x＝(2ρ-1)sin(ψ _ρ)

Wherein, a _y=-sin (ψ _ρ)

b _y＝cos(ψ _ρ)

$c_x=2\sqrt{\mathrm{\ρ}(1-\mathrm{\ρ})}$

Wherein ρ, ψ _ρBe respectively backscattering coefficient related coefficient amplitude and phase place, z is that the obedience average is that 0 variance is σ ²Normal distribution random number, and and x ₁y ₁Separate.

Described interference SAR echo data emulation mode based on the POS exercise data, the auxiliary antenna backscattering coefficient real part x of its described generation ₂With imaginary part y ₂Satisfy following three conditions:

1) x ₂, y ₂Be that the obedience average is 0, variance is σ ²The stochastic variable of normal distribution;

2) x ₂, y ₂Between related coefficient be 0;

3) main antenna backscattering coefficient x ₁+ jy ₁With auxiliary antenna backscattering coefficient x ₂+ jy ₂Between related coefficient be

In expression formula, j and e are respectively imaginary unit and natural constant.

Described interference SAR echo data emulation mode based on the POS exercise data, its described the 3rd step is according to the radar of first and second step foundation and model space geometric and the backscattering model of target, adopts the time domain echo signal model to produce original echoed signals; The time domain echo algorithm is on the basis of radar emission continuous impulse, along with the motion of Texas tower, generates the echoed signal of each pulse.

Described interference SAR echo data emulation mode based on the POS exercise data in its described the 3rd step, comprises that step is as follows:

A) for the orientation to moment t _s, the oblique distance R of target scattering unit (i, j) in the compute beam irradiation area _ij, and definite R _ijThe range gate m at place;

B) the adjust the distance orientation echoed signal g of a m _aAdd the doppler phase contribution from point (i, j):

g _a=g _a+ σ _{I, j}w _aExp (j4 π R _ij/ λ), wherein, λ is wavelength, w _aThe antenna radiation pattern gain, σ _{I, j}It is backscattering coefficient;

C) repeat the a-b step, travel through all scattering points that this orientation moment radar illumination arrives, obtain orientation t constantly _sOn the orientation echoed signal g that has a few _a

D) with g _aWith range transmission signal convolution, obtained the echoed signal of a pulse, travel through the echoed signal that each orientation obtains whole simulating scenes constantly.

E) according to a)-d) going on foot the echo data that calculates respectively double antenna, then pass through CS (ChirpScaling) algorithm and carry out the SAR imaging, then compensation obtains interference fringe through kinematic error.

The inventive method has realized based on the emulation of the airborne Interference synthetic aperture radar of actual motion data (SAR) original echo.

Description of drawings

Fig. 1 is based on the geometric simulation scheme schematic diagram of POS data;

Fig. 2 is time domain echo generating algorithm process flow diagram;

Fig. 3 is major-minor Antenna Correlation backscattering coefficient figure, wherein:

Fig. 3 a is main antenna backscattering coefficient map of magnitudes;

Fig. 3 b produces according to correlativity the auxiliary antenna backscattering coefficient amplitude that principle produces;

Fig. 4 is target landform (DEM) corresponding to simulating scenes;

Fig. 5 is two passage original echo data, wherein:

Fig. 5 a is the main antenna original echo data that emulation obtains;

Fig. 5 b is auxiliary antenna echo data;

Fig. 6 processes rear SAR image to echo data, wherein:

Fig. 6 a is through main antenna SAR picture amplitude figure after the CS imaging processing;

Fig. 6 b is the auxiliary antenna picture amplitude figure that obtains after processing;

The interferometric phase image that Fig. 7 emulation obtains, wherein:

Fig. 7 a is the Perfect Interferometry bar graph;

Fig. 7 b is that emulated data does not carry out through imaging processing the interference fringe that motion compensation obtains;

Fig. 7 c is the interference fringe picture through obtaining after motion compensation;

Fig. 8 is based on the interference SAR echo data simulation flow figure of POS exercise data.

Embodiment

A kind of interference SAR data simulation method based on the POS exercise data of the present invention, being that carrier aircraft position of platform and attitude information that movement measurement system records are fused in the emulation of interference SAR echo data, is a kind of echo simulation method based on the actual motion error information.The specific implementation step is as follows: 1) consider to calculate the double antenna phase centre location under the condition of motion excursion and attitude disturbance.

As shown in Figure 1, positional information and attitude information can be incorporated in the calculating of antenna phase center coordinate through three coordinate system rotation.

At first several important Coordinate system definitions are described.The earth's core rotating coordinate system definition: true origin is positioned at the earth's core, and Z axis points to earth's axis, and X-axis is pointed to the zero degree meridian, Y-axis and X, and Z axis consists of right-handed system; The definition of the earth surface level coordinate system: coordinate origin is the scene center of observed object early, X-axis point to geographical south to, the XY plane is the earth surface level, so Y-axis points to the due east direction, the Z axis vertical ground upwards; The scene Coordinate system definition: coordinate origin is the scene center of observed object early, and X-axis is pointed to the desirable heading of carrier aircraft platform, and the XY plane is the earth surface level, and the Z axis vertical ground upwards.

The earth's core rotating coordinate system and the earth surface level coordinate system transformational relation can be expressed as:

E _p＝A _pg(E _g-A _pg0)

$A_{\mathrm{pg}}=\left(\begin{array}{ccc}\cos (\mathrm{\π}/2-{\mathrm{\Φ}}_0)& 0& -\sin (\mathrm{\π}/2-{\mathrm{\Φ}}_0)\\ 0& 1& 0\\ \sin (\mathrm{\π}/2-{\mathrm{\Φ}}_0)& 0& \cos (\mathrm{\π}/2-{\mathrm{\Φ}}_0)\end{array}\right)\left(\begin{array}{ccc}\cos {\mathrm{\Λ}}_0& {\sin \mathrm{\Λ}}_0& 0\\ {-\sin \mathrm{\Λ}}_0& {\cos \mathrm{\Λ}}_0& 0\\ 0& 0& 1\end{array}\right)$

E wherein _gE _pBe respectively the earth's core rotating coordinate system and the earth surface level coordinate system coordinate, A _pg0The coordinate of the earth surface level coordinate system true origin under the rotating coordinate system of the earth's core.Φ ₀And Λ ₀Respectively geodetic latitude and the geodetic longitude of the earth surface level coordinate system true origin.The earth surface level coordinate system and scene coordinate system transformational relation can be expressed as:

E _c＝A _cp.E _p

Wherein $A_{\mathrm{cp}}=\left(\begin{array}{ccc}{\cos \mathrm{\θ}}_{\mathrm{pc}}& {\sin \mathrm{\θ}}_{\mathrm{pc}}& 0\\ {-\sin \mathrm{\θ}}_{\mathrm{pc}}& {\cos \mathrm{\θ}}_{\mathrm{pc}}& 0\\ 0& 0& 1\end{array}\right)$

E wherein _cCoordinate under the scene coordinate system, θ _pcCarrier aircraft flying platform direction and Due South to angle.Through above-mentioned coordinate transform, can calculate POS center scene coordinate system coordinate E _c0:

E _c0＝A _cpA _pg(E _g-A _pg0)

Attitude information causes the shake of antenna mounting arm, thereby affects the position of double antenna phase center.Double antenna coordinate under the POS platform coordinate system can be expressed as:

E _pos1＝A _re.[0?-Bcosα/2?-Bsinα/2] ^T

E _pos2＝A _re.[0?Bcosα/2?Bsinα/2] ^T

Wherein: $A_{\mathrm{re}}=\left[\begin{array}{ccc}1& 0& 0\\ 0& {\cos \mathrm{\θ}}_r& {-\sin \mathrm{\θ}}_r\\ 0& {\sin \mathrm{\θ}}_r& {\cos \mathrm{\θ}}_r\end{array}\right]\left[\begin{array}{ccc}{\cos \mathrm{\θ}}_p& 0& {\sin \mathrm{\θ}}_p\\ 0& 1& 0\\ {-\sin \mathrm{\θ}}_p& 0& {\cos \mathrm{\θ}}_p\end{array}\right]\left[\begin{array}{ccc}{\cos \mathrm{\θ}}_y& {-\sin \mathrm{\θ}}_y& 0\\ {\sin \mathrm{\θ}}_y& {\cos \mathrm{\θ}}_y& 0\\ 0& 0& 1\end{array}\right]$

θ _rθ _pθ _yRespectively the three-axis attitude angle: roll angle, the angle of pitch and crab angle, B is base length, and α is the baseline inclination angle, and POS is positioned at the center of baseline.Again with the platform coordinate system coordinate transformation in the scene coordinate system:

E _c1＝E _pos1+E _c0

E _c2＝E _pos2+E _c0

So far obtain double antenna scene coordinate system coordinate, thereby set up the spatial relation of radar and target.

2) utilize true SAR picture amplitude data, generate the plural backscattering coefficient pair of correlativity.

Backscattering coefficient comprises amplitude and phase place, the sharp keen distribution of whose amplitude obeys, and phase place is obeyed evenly and is distributed.Yet can not directly simply generate two groups of independently equally distributed random phases, binary channels backscattering coefficient phase place has correlativity.Here in conjunction with actual SAR picture amplitude data, provide a kind of correlativity backscattering coefficient production method, method step is as follows:

A) with the SAR picture amplitude as main antenna backscattering coefficient amplitude, be created between [π π] and obey equally distributed random phase.

B) provide the auxiliary antenna backscattering coefficient of a kind of correlativity to generate scheme here.Basic thought is by adding the random number of an independent normal distribution on the linear combination basis of main antenna backscattering coefficient real part and imaginary part, in order to control the correlativity between major-minor antenna backscattering coefficient, generates step as follows:

Get main antenna backscattering coefficient γ ₁Real part x ₁With imaginary part y ₁, x ₁y ₁Obeying average is 0, and variance is σ ²Normal distribution and separate.We can set up real part and the imaginary part of auxiliary antenna backscattering coefficient so:

x ₂＝a _xx ₁+b _xy ₁+c _xz

y ₂＝a _yx ₁+b _yy ₁

a _x＝(2ρ-1)cos(ψ _ρ)

b _x＝(2ρ-1)sin(ψ _ρ)

Wherein, a _y=-sin (ψ _ρ)

b _y＝cos(ψ _ρ)

$c_x=2\sqrt{\mathrm{\ρ}(1-\mathrm{\ρ})}$

Wherein ρ, ψ _ρBe respectively backscattering coefficient related coefficient amplitude and phase place, z is that the obedience average is that 0 variance is σ ²Normal distribution random number, and and x ₁y ₁Separate.Can be verified the auxiliary antenna backscattering coefficient real part x that following formula generates ₂With imaginary part y ₂Satisfy following three conditions:

(1) x ₂, y ₂Be that the obedience average is 0, variance is σ ²The stochastic variable of normal distribution.

(2) x ₂, y ₂Between related coefficient be 0.

(3) main antenna backscattering coefficient x ₁+ jy ₁With auxiliary antenna backscattering coefficient x ₂+ jy ₂Between related coefficient be

In expression formula, j and e are respectively imaginary unit and natural constant.

3) introduce DEM information, generate the two-way original echoed signals according to echo signal model.

According to model space geometric and the backscattering model of the radar of setting up previously and target, adopt the time domain echo signal model to produce original echoed signals.The basic thought of time domain echo algorithm is on the basis of radar emission continuous impulse, along with the motion of Texas tower, generates the echoed signal of each pulse.The step of algorithm following (as Fig. 2):

A) for the orientation to moment t _s, the oblique distance R of target scattering unit (i, j) in the compute beam irradiation area _ij, and definite R _ijThe range gate m at place.

B) the adjust the distance orientation echoed signal g of a m _aAdd the doppler phase contribution from point (i, j):

g _a=g _a+ σ _{I, j}w _aExp (j4 π R _ij/ λ), wherein λ is wavelength, w _aThe antenna radiation pattern gain, σ _{I, j}It is backscattering coefficient.

C) repeat the a-b step, travel through all scattering points that this orientation moment radar illumination arrives.Obtain orientation t constantly _sOn the orientation echoed signal g that has a few _a

D) with g _aWith range transmission signal convolution, obtained the echoed signal of a pulse, travel through the echoed signal that each orientation obtains whole simulating scenes constantly.

E) according to a)-d) going on foot the echo data that calculates respectively double antenna, then pass through CS (ChirpScaling) algorithm and carry out the SAR imaging, then compensation obtains interference fringe through kinematic error.

In Fig. 1, the positional information that comprises in the POS data (latitude, longitude and height) through the earth's core rotating coordinate system and the coordinate transform of the earth surface level coordinate system, is transformed in the scene coordinate system, obtains the coordinate of POS center in the scene coordinate system.Be positioned at the center of baseline sway brace due to POS, therefore can merge attitude information in the POS data, resolve the major-minor antenna phase center in baseline two ends coordinate under the scene coordinate system.

Fig. 2 is time domain echo algorithm flow process, and basic thought is on the basis of radar emission continuous impulse, along with the motion of Texas tower, generates the echoed signal of each pulse.

Fig. 3 a is main antenna backscattering coefficient map of magnitudes, and Fig. 3 b produces according to correlativity the auxiliary antenna backscattering coefficient amplitude that principle produces, and the corresponding related coefficient of the corresponding backscattering coefficient of major-minor antenna is 0.98.

Fig. 4 is the simulating scenes altitude figures, and the scene border district shape that keeps left is comparatively smooth, and rising and falling appears in the right side landform.

Fig. 5 a is the main antenna original echo data that emulation obtains, and Fig. 5 b is auxiliary antenna echo data.

Fig. 6 a is through main antenna SAR picture amplitude figure after the CS imaging processing, and Fig. 6 b is the auxiliary antenna picture amplitude figure that obtains after processing, and echo data has obtained focusing on preferably.

Fig. 7 a is the Perfect Interferometry bar graph, and Fig. 7 b is that emulated data does not carry out through imaging processing the interference fringe that motion compensation obtains, and Fig. 7 c is through the interference fringe picture that obtains after motion compensation, conforms to desirable striped.

Fig. 8 is based on the flow process of POS exercise data interference SAR echo data emulation mode, and its step is as follows:

Interference SAR echo simulation scheme is divided into three parts, and first utilizes coordinate transform to calculate double antenna phase center coordinate under the scene coordinate system; Second portion is take true SAR view data as the basis, generates correlativity plural number backscattering coefficient pair; Third part is introduced the DEM terrain information exactly, calculate two-way original echo data according to echo signal model, thereby emulation obtains SAR image and interference fringe.

Claims (7)

1. interference SAR echo data emulation mode based on the POS exercise data, it is characterized in that: by setting up the transformational relation of POS coordinate system and target scene coordinate system, the kinematic error of carrier aircraft platform is fused in the calculating of interference synthetic aperture radar echo, to realize the airborne interference SAR original echo emulation based on the actual motion data; Comprise the following steps: the first step, utilize coordinate transform to calculate double antenna phase center coordinate under the scene coordinate system; Second step take true SAR view data as the basis, generates correlativity plural number backscattering coefficient pair; The 3rd step, introduce the DEM terrain information, calculate two-way original echo data according to echo signal model, obtain SAR image and interference fringe through imaging with interfering to process.

2. the interference SAR echo data emulation mode based on the POS exercise data according to claim 1, it is characterized in that the described first step is through three coordinate system rotation, positional information and attitude information are incorporated in the calculating of antenna phase center coordinate, comprise:

1) actual the earth's core, the POS center rotating coordinate system coordinate conversion that comprises positional information is arrived the earth surface level coordinate system;

2) be transformed into the scene coordinate system from the earth surface level coordinate system again;

3) calculate antenna phase center at the platform coordinate system coordinate according to the carrier aircraft attitude information, it is transformed in the scene coordinate system again, obtain double antenna coordinate under the scene coordinate system, set up the space geometry relation of radar and target, thereby realized the introducing of positional information and attitude information kinematic error in echo calculates.

3. the interference SAR echo data emulation mode based on the POS exercise data according to claim 1, is characterized in that, described second step is to utilize true SAR picture amplitude data, generates the plural backscattering coefficient pair of correlativity, comprises step:

A) with the SAR picture amplitude as main antenna backscattering coefficient amplitude, be created between [π π] and obey equally distributed random phase;

B) on the linear combination basis of main antenna backscattering coefficient real part and imaginary part, add the random number of an independent normal distribution, in order to control the correlativity between major-minor antenna backscattering coefficient, generate real part and the imaginary part of auxiliary antenna backscattering coefficient.

4. the interference SAR echo data emulation mode based on the POS exercise data according to claim 3, is characterized in that, real part and the imaginary part of the auxiliary antenna backscattering coefficient of described generation, and step is as follows:

Get main antenna backscattering coefficient γ ₁Real part x ₁With imaginary part y ₁, x ₁y ₁Obeying average is 0, and variance is σ ²Normal distribution and separate; The real part of auxiliary antenna backscattering coefficient and imaginary part are:

x ₂＝a _xx ₁+b _xy ₁+c _xz

y ₂＝a _yx ₁+b _yy ₁

Wherein, $\begin{array}{c}{a}_x=(2\mathrm{\ρ}-1)\cos \left({\mathrm{\ψ}}_{\mathrm{\ρ}}\right)\\ b_x=(2\mathrm{\ρ}-1)\sin \left({\mathrm{\ψ}}_{\mathrm{\ρ}}\right)\\ a_y=-\sin \left({\mathrm{\ψ}}_{\mathrm{\ρ}}\right)\\ b_y=\cos \left({\mathrm{\ψ}}_{\mathrm{\ρ}}\right)\\ c_x=2\sqrt{\mathrm{\ρ}(1-\mathrm{\ρ})}\end{array}$

Wherein ρ, ψ _ρBe respectively backscattering coefficient related coefficient amplitude and phase place, z is that the obedience average is that 0 variance is σ ²Normal distribution random number, and and x ₁y ₁Separate.

5. the interference SAR echo data emulation mode based on the POS exercise data according to claim 4, is characterized in that, the auxiliary antenna backscattering coefficient real part x of described generation ₂With imaginary part y ₂Satisfy following three conditions:

1) x ₂, y ₂Be that the obedience average is 0, variance is σ ²The stochastic variable of normal distribution;

2) x ₂, y ₂Between related coefficient be 0;

3) main antenna backscattering coefficient x ₁+ jy ₁With auxiliary antenna backscattering coefficient x ₂+ jy ₂Between related coefficient be

In expression formula, j and e are respectively imaginary unit and natural constant.

6. the interference SAR echo data emulation mode based on the POS exercise data according to claim 1, it is characterized in that, described the 3rd step, be according to the radar of first and second step foundation and model space geometric and the backscattering model of target, adopt the time domain echo signal model to produce original echoed signals; The time domain echo algorithm is on the basis of radar emission continuous impulse, along with the motion of Texas tower, generates the echoed signal of each pulse.

7. according to claim 1 or 6 described interference SAR echo data emulation modes based on the POS exercise data, is characterized in that, in described the 3rd step, comprises that step is as follows:

A) for the orientation to moment t _S, the oblique distance R of target scattering unit (i, j) in the compute beam irradiation area _ij, and definite R _ijThe range gate m at place;

B) the adjust the distance orientation echoed signal g of a m _aAdd the doppler phase contribution from point (i, j):

g _a=g _a+ σ _{I, j}w _aExp (j4 π R _ij/ λ), wherein, λ is wavelength, w _aThe antenna radiation pattern gain, σ _{I, j}It is backscattering coefficient;

C) repeat the a-b step, travel through all scattering points that this orientation moment radar illumination arrives, obtain orientation t constantly _SOn the orientation echoed signal g that has a few _a

D) with g _aWith range transmission signal convolution, obtained the echoed signal of a pulse, travel through the echoed signal that each orientation obtains whole simulating scenes constantly;

E) according to a)-d) going on foot the echo data that calculates respectively double antenna, then pass through CS (ChirpScaling) algorithm and carry out the SAR imaging, then compensation obtains interference fringe through kinematic error.

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