CN103645466B - Polarization calibration method based on platform attitude time variation compensation - Google Patents

Abstract

The invention relates to a polarization calibration method based on platform attitude time variation compensation. The method comprises steps that: S1, two-dimensional echo data is acquired; S2, scattering matrix observation values of a calibrator at one same irradiation time are extracted; S3, an incidence angle and an oblique angle of the calibrator irradiated by electromagnetic waves are acquired; S4, when the calibrator receives polarization calibration angles of the electromagnetic waves, deflection amount at each irradiation time is acquired; S5, full polarization echo data after attitude error compensation correction is acquired; S6, azimuth compression of the full polarization echo data after the attitude error compensation correction is carried out to acquire an image; and S7, scattering matrixes after calibrator deflection amount correction are extracted in each polarization channel of the image, an unbalance degree which is left over in the scattering matrixes after calibrator deflection amount correction and is led in by a transceiver module of a full polarization synthetic aperture radar system, and crosstalk in each channel are evaluated, error correction of the full polarization synthetic aperture radar system is realized, and the full polarization synthetic aperture radar image is acquired.

Description

A kind of polarimetric calibration method compensated based on platform stance time variation

Technical field

The invention belongs to polarimetric synthetic aperture radar (PolSAR) signal transacting field, be specifically related to polarimetric calibration process and compensation of attitude error method

Background technology

Polarimetric calibration is the important step of polarimetric synthetic aperture radar (PolSAR) signal transacting, and its fundamental purpose is corrective system error, restores the polarization scattering characteristics of target in imaging results.Thus only have by polarimetric calibration process, from PolSAR extracting target from images polarization information accurately, follow-up application could be supported.

Existing PolSAR polarimetric calibration method mainly comprises the three class scaling algorithms based on point target, distribution objectives and compound target.Wherein based on the scaling algorithm of distribution objectives, with Sarabandi algorithm [Kamal Sarabandi.Calibration of a Polarimetric Synthetic ApertureRadar Using a Known Distributed Target.IEEE Trans on Geoscienceand Remote Sensing.Vo1.32, No3, May 1994] be example, putting of artificial point target can be avoided, but because current people understand not deeply the polarization scattering characteristics of various ground object target, thus the ground object target that the data utilizing Polarization scattering meter to obtain are selected as scaled reference target is needed, this makes such scaling algorithm be subject to larger restriction in actual use, based on the scaling algorithm of compound target, with Quegan algorithm for representative [Shaun Quegan.A Unified Algorithmfor Phase and Cross-Talk Cal ibration of Polarimetric Data---Theory and ObservationS, IEEE Trans on Geoscience and RemoteSensing.Vo1.32, No.1, January 1994], according to the scattering properties supposition taken out, choose targetedly ground object target as scaled reference target, again in conjunction with a small amount of artificial point target, realize the estimation of calibration model parameter, but the method is also subject to larger restriction on ground object target is selected, especially be often difficult in airborne PolSAR imaging scene find the region meeting supposition, although the scaling algorithm based on point target will relate to the operation bidirectional such as to put in advance of specific scaler, but the scattering properties due to scaler is known and controlled, calibration processing procedure is fairly simple, and do not need the priori depending on imaging region, calibration precision is also relatively high.Thus the process of actual PolSAR system calibration is carried out based on design point target scaler in advance usually.

Scaling algorithm kind based on point target is more.Wherein Whitt algorithm [Michael W.Whittetc.A General Polarimetric Radar Cal ibration Technique, IEEE Transon Antennas and Propagation.Vo1.39, No.1, January 1991] do not need to make any hypothesis to radar system distortion matrix, also relatively less to the restrictive condition of the reverberator for calibrating, the selection of calibration target has very large dirigibility, is the good algorithm of practicality.

The method is as follows based on SYSTEM ERROR MODEL:

M=Ae ^jφR ^TST+N

Wherein, M represents scattering matrix observed reading, S represents normalized scattering matrix theory value, the systematic errors such as the channel imbalance degree of R matrix representation receiving end module and interchannel crosstalk and the polarization distortion caused, the systematic errors such as the channel imbalance degree of T matrix representation transmitting terminal module and interchannel crosstalk and the polarization distortion caused, A represents absolute amplitude value, and φ represents absolute phase values, N represents additivity observation noise, is usually left in the basket in processes.

Whitt algorithm, based on above-mentioned model, utilizes three the difference target correspondence polarization matrixes meeting subsequent treatment restriction, can obtain the estimated value of distortion matrix R, T parameter in model.

But above-mentioned observation model, main it is considered that crosstalk and gain unbalancedness equal error between the passage that caused by system hardware imperfection, do not consider as time variation errors such as attitudes.In actual applications, often occur utilizing and lay scaler and estimate the distortion that obtains and inapplicable with other targets in scene, thus make the error correction hydraulic performance decline of scaling algorithm.

The people such as bright peak [Feng Ming etc.Improved Calibration method of theairborne polarimetric SAR] analyze platform stance factor, improve as follows by calibration model:

M=Ae ^jφR ^TS _θT+N=Ae ^jφR ^TD(θ)·S·D ^-1(θ)T+N

Wherein, S _θrepresent the target scattering matrix under affecting by attitude, can S be expressed as _θ=D (θ) SD ^-1(θ), $D\left(\mathrm{\θ}\right)=\left[\begin{array}{cc}\cos \mathrm{\θ}& -\sin \mathrm{\θ}\\ \sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right]$ For rotational transformation matrix, θ represents the deflection of the polarization orientation angle (polarization orientation angle, POA) caused by attitude, and the amount of deflection computing method that document provides are as follows:

$\tan \mathrm{\θ}=\frac{\sin \mathrm{\φ}\sin {\mathrm{\θ}}_p-\cos \mathrm{\φ}{\cos \mathrm{\θ}}_p\sin {\mathrm{\θ}}_y}{\cos {\mathrm{\θ}}_p{\cos \mathrm{\θ}}_y},$

θ in above formula _y, θ _prepresent the crab angle for portraying platform stance and the angle of pitch respectively.In conjunction with above-mentioned model, this document propose the distortion matrix R obtained by original Whitt algorithm, on T estimated value basis, the right side is taken advantage of and premultiplication D (θ) and D respectively ^-1(θ), to eliminate the systematic distortion Matrix Estimation error that attitude is brought.

Although there is the distortion effect considering that flying platform attitude produces target scattering matrix in prior art in calibration model, but the impact of platform stance on target polarization characteristic is expressed as the skew that a fixed value occurs the polarization of ele orientation angle irradiating this target by this model, the mode of portraying like this is a kind of coarse being similar to, have ignored the variation that platform stance occurs within the target illumination time, the visual angle change of i.e. attitude time variation, and target relative antenna.Thus, with above-mentioned model attitude error compensated and can there is the following defect:

Above-mentioned model is based upon on target scattering matrix basis that imaging results extracts, and in imaging results, a point target only corresponds to a polarization rotation amount Δ θ.But in reality, attitude becomes to when existing with orientation within the target illumination time, the em polarization direction amount of deflection thus caused by attitude, in this point target range of exposures, not fixed value, each target echo amount distortion gathering the moment is not quite similar.If with above-mentioned existing method, in SAR image, extract scattering matrix compensate to carry out attitude impact, then the relevant process of imaging has made not attitude impact in the same time that aliasing occurs, namely replaces attitude sequence in exposure time range with beam center moment corresponding attitude data.It is more coarse that this step substitutes, from emulation experiment, if the deflection of the polarization orientation angle in irradiation time to be equivalent to the crosstalk error of receiving end or transmitting terminal, when then there is ± 0.5 ° of deflection in orientation angle, this error span is maximum can more than 40dB, and practical engineering experience is known, polarization orientation angle completely may more than the deflection of 0.5 ° in range of exposures, especially along with SAR system resolution improves gradually, antenna bearingt to beam angle increase, the target illumination time is increased, and the impact become during attitude will can not be ignored more.

Analyze attitude angle in above-mentioned model when causing the deflection of polarised direction, only consider and irradiate the situation that target is in positive side-looking.In reality, even if in positive side-looking SAR system, when target is in the non-beam center moment, between target and antenna, also there is stravismus.Angle of squint can affect polarization of ele direction relative exposure target equally and deflect, and thus analyzes the different moment platform stance that irradiates when causing the deflection in polarization of ele direction, also will consider the coupling influence that angle of squint produces simultaneously.

In a word, prior art based on model accuracy and comprehensive on existing problems, its corresponding compensation method also needs to revise.

Summary of the invention

(1) technical matters that will solve

For the scarce filling of prior art, the object of this invention is to provide a kind of polarimetric calibration method compensated based on platform stance time variation.

(2) technical scheme

For reaching described object, the technical scheme that the invention provides a kind of polarimetric calibration method based on the compensation of platform stance time variation comprises:

Step S1: the raw radar data of four POLARIZATION CHANNEL obtained from the polarimetric synthetic aperture radar system be loaded into platform carries out distance to compression, and range migration correction process and interchannel registration process, obtain two-dimentional echo data;

Step S2: according to the synthetic aperture time-parameters of scaler orientation to coordinate and polarimetric synthetic aperture radar system, and from two-dimentional echo data, extracts the scattering matrix observed reading M (η) of scaler at same irradiation moment η;

Step S3: utilize scaler orientation to and distance to coordinate, and polarimetric synthetic aperture radar system irradiation low coverage and flying height parameter, calculate incident angle φ and the angle of squint θ of electromagnetic wave irradiation scaler _sq;

Step S4: utilize platform flight attitude data, incident angle φ and angle of squint θ _sq, calculate the amount of deflection θ (η) that each irradiation moment η scaler receives polarization of ele orientation angle;

Step S5: utilize scaler to receive the amount of deflection of polarization of ele orientation angle, carry out amount of deflection correction to scattering matrix observed reading M (η), obtains the complete polarization echo data after compensation of attitude error correction;

Step S6: orientation is carried out to compression to the complete polarization echo data after compensation of attitude error corrects, obtains image;

Step S7: in each POLARIZATION CHANNEL of image, extract the scattering matrix after the correction of scaler amount of deflection, adopt the Whitt algorithm carrying out scene calibration based on scaler, to remain in scaler amount of deflection correct after scattering matrix in, the degree of unbalancedness introduced by polarimetric synthetic aperture radar systems radiate and receiver module and each channels crosstalk estimate, realize polarimetric synthetic aperture radar Systematic Error Correction, obtain polarimetric synthetic aperture radar image.

(3) beneficial effect

1), when the present invention sets up amount of deflection θ (η) model of scaler reception polarization of ele orientation angle, angle of squint θ is contained _sq, when the antenna of polarimetric synthetic aperture radar system involved in the present invention is in stravismus state, method of the present invention, to the estimated accuracy of degree of unbalancedness and each channels crosstalk, is higher than existing method;

2) when the present invention sets up amount of deflection θ (η) model of scaler reception polarization of ele orientation angle, consider the time variation that attitude data is intrinsic, not adopt in existing algorithm based on scaler irradiation time in attitude data to remain unchanged this hypothesis, thus the present invention features the characteristic of attitude data more realistically, make method of the present invention to the estimated accuracy of degree of unbalancedness and each channels crosstalk, be higher than existing method.

Accompanying drawing explanation

Fig. 1 is the process flow diagram that the present invention is based on the polarimetric calibration method that platform stance time variation compensates.

Fig. 2 be the inventive method validity use the remote sensing images of synthetic-aperture radar SAR, mark region with different housing in figure and comprise dissimilar scaler, wherein, zero mark for trihedral angle, △ mark what be that 0 ° of dihedral angle, marks is 45 ° of dihedral angles.In image, each scaler numbering is P1, P2A, P2, P2B, P3, P4A, P4, P4B, P5, P6A, P6, P6B from left to right.

Embodiment

For making the object, technical solutions and advantages of the present invention clearly understand, below in conjunction with instantiation, and with reference to accompanying drawing, the present invention is described in more detail.

As Fig. 1 illustrates that technical scheme of the present invention is as follows:

1) two-dimentional echo data is obtained

The raw radar data of four POLARIZATION CHANNEL obtained from the polarimetric synthetic aperture radar system be loaded into platform carries out distance to compression, and range migration correction process and interchannel registration process, obtain two-dimentional echo data;

2) from raw radar data, scaler scattering matrix is extracted

From the two-dimentional echo data after the 1st step process, according to the synthetic aperture time-parameters of scaler orientation to coordinate and polarimetric synthetic aperture radar system, extract scaler under four kinds of polarization modes, the echo data m that same irradiation moment η is corresponding _hh(η), m _hv(η), m _vh(η), m _vv(η), by four groups of data composition scattering matrix observed reading M (η).Described four groups of data are with following form:

$\left[\begin{array}{cc}{m}_{\mathrm{hh}}\left(\mathrm{\η}\right)& m_{\mathrm{hv}}\left(\mathrm{\η}\right)\\ m_{\mathrm{vh}}\left(\mathrm{\η}\right)& m_{\mathrm{vv}}\left(\mathrm{\η}\right)\end{array}\right]$

This step realizes from echo data, extract scaler scattering matrix, compensates, to provide within the scope of target illumination each orientation to the scattering matrix observation data in moment for follow-up to attitude factor time variation.

3) incident angle and angle of squint data are obtained

Utilize scaler orientation to and distance to coordinate, and polarimetric synthetic aperture radar system irradiation low coverage and flying height parameter, calculate incident angle φ and the angle of squint θ of electromagnetic wave irradiation scaler _sq;

4) the polarization orientation angle amount of deflection that attitude causes is become when calculating

Utilize each irradiation moment platform crab angle θ _y(η), pitching angle theta _p(η) with roll angle θ _r(η) platform flight attitude data and step into firing angle φ and antenna angle of squint θ by the 3rd _sq, amount of deflection θ (η) model representation calculating each irradiation moment η scaler reception polarization of ele orientation angle is as follows:

$\tan \mathrm{\θ}\left(\mathrm{\η}\right)=\frac{\sin \mathrm{\φ}\sin {\mathrm{\θ}}_p-\cos \mathrm{\φ}{\cos \mathrm{\θ}}_p{\sin \mathrm{\θ}}_y}{{\cos \mathrm{\θ}}_{\mathrm{sq}}{\cos \mathrm{\θ}}_p{\cos \mathrm{\θ}}_y-{\sin \mathrm{\θ}}_{\mathrm{sq}}(\cos \mathrm{\φ}{\sin \mathrm{\θ}}_p+\sin \mathrm{\φ}{\cos \mathrm{\θ}}_p{\sin \mathrm{\θ}}_y)}$

θ in above formula _pit is the pitching angle theta with irradiation time η change _p(η) reduced representation, θ _ythe crab angle θ with irradiation time η change _y(η) reduced representation; θ _sqthe antenna relative calibration device angle of squint θ with irradiation time η change _sq(η) reduced representation, φ represents the incident angle of electromagnetic wave irradiation scaler; θ _p, θ _ychange with irradiation time feature attitude time become feature, θ _sqfeature the coupling influence of antenna angle of squint.Above-mentioned model, feature platform stance data and angle of squint, incident angle to the coupling influence of the orientation angle that polarizes, thus for occurring the situation that antenna is looked side ways in actual polarization sensitive synthetic aperture radar system, this model still can be used for calculate polarization orientation angle amount of deflection, this point compensate for the limitation only considering positive side-looking in existing method [FengMing etc. Improved Calibration method of the airborne polarimetricSAR].

5) polarization rotation amount corrects

Utilize and calculate the orientation angle amount of deflection that scaler receives polarization of ele, carry out amount of deflection correction to each moment scattering matrix observed reading, obtain the complete polarization echo data after compensation of attitude error correction, concrete compensation method is as follows:

S _{θ_comp}(η)=D ^-1[θ(η)]·M(η)·D[θ(η)]

Wherein, S _{θ _ comp}(η) scattering matrix after irradiating moment η attitude error rectification is represented, η be four same orientation of passage to the irradiation moment, M (η) represents moment η scattering matrix observed reading, D [θ (η)] represents moment η polarization orientation angle deflection matrix, and concrete form is:

$D\left[\mathrm{\θ}\left(\mathrm{\η}\right)\right]=\left[\begin{array}{cc}\cos \mathrm{\θ}\left(\mathrm{\η}\right)& -\sin \mathrm{\θ}\left(\mathrm{\η}\right)\\ \sin \mathrm{\θ}\left(\mathrm{\η}\right)& \cos \mathrm{\θ}\left(\mathrm{\η}\right)\end{array}\right],$

D ^-1[θ (η)] is its inverse matrix,

The moment η polarization orientation angle amount of deflection of θ (η) for utilizing attitude data to obtain.

This step compensates the pointwise of polarization orientation angle amount of deflection on two-dimentional echo data, the platform stance data of inscribing change when scaler difference is irradiated can be compensated one by one, compensate in existing method and carry out the compensation of polarization orientation angle amount of deflection at one-tenth image field, thus ignore the defect that target illumination scope inner platform attitude data exists time variation.

6) imaging processing

Orientation is carried out to compression to each POLARIZATION CHANNEL echo data after completing compensation of attitude error correction, is embodied as picture; By the operation of former step, the polarization scattering matrix that scaler is extracted in imaging results has eliminated the impact of attitude time variation.

7) scaling correction of system interference and degree of unbalancedness

From each POLARIZATION CHANNEL of four not co polarization diagram pictures, extract scaler amount of deflection correct after scattering matrix.Adopt the Whitt algorithm carrying out scene calibration based on scaler, in conjunction with to remain in scaler amount of deflection correct after scattering matrix in, the degree of unbalancedness introduced by polarimetric synthetic aperture radar systems radiate and receiver module and each channels crosstalk estimate, realize the estimation of system degree of unbalancedness and crosstalk, realize polarimetric synthetic aperture radar Systematic Error Correction, obtain polarimetric synthetic aperture radar image.The concrete methods of realizing of Whitt algorithm can list of references [Michael W.Whitt etc.AGe neral Polarimetric Radar Calibration Technique, IEEE Trans onAntennas and Propagation.Vol.39, No.1, January 1991].To estimate that the estimated value of system degree of unbalancedness and the crosstalk obtained is applied to the scattering matrix distortion correction of other targets in scene.

Alternative technical scheme of the present invention

(1) for the technical scheme of system degree of unbalancedness and crosstalk estimation, after echo data is corrected, as adopted other scaling algorithms based on point target scaler except Whitt algorithm, to the calibration process of imaging results, also belong within category of the present invention.

(2) for the technical scheme that polarization orientation angle amount of deflection corrects, polarization of ele orientation angle is caused to deflect for other factors except attitude, and cause the distortion of target polarization characteristic, also model of the present invention can be utilized to portray, and can utilize in technical scheme flow process amount of deflection correction is carried out to each collection moment.Thus use this patent method, to correct the improvement scaling algorithm based on polarization orientation angle deflection (no matter which kind of factor causing deflection by), all belong within category of the present invention.

Process example below by real data verifies advantage of the present invention.We carry out imaging and calibration process to the airborne full-polarization SAR experimental data of pattern-band that Chinese Academy of Sciences electron institute is carried out.One piece of scaling experiment field is comprised in this experiment range of exposures, what mark is trihedral angle scaler to concrete scene with zero in figure as shown in Figure 2, what △ marked is 0 ° of dihedral angle scaler, what marked is 45 ° of dihedral angle scaler, have 12 scaler, table 1 gives each test scaler type, the scaler numbering of the type is belonged in corresponding scattering matrix theory value and figure, we choose two groups of scaler groups and (wherein often comprise the different scaler of three types in group, be respectively { p2, p2A, p2B} and { p6, p6A, p6B}) for the estimation of degree of unbalancedness and each channels crosstalk, and using all the other targets as test point.First use document [Michael W.Whitt etc.A General Polarimetric RadarCalibration Technique, IEEE Trans on Antennas and Propagation.Vo1.39, No.1, January 1991] scaling algorithm that provides directly processes scaler group, obtain the estimated value of degree of unbalancedness and each channels crosstalk, and correcting test point by estimated value, the results are shown in Table 2 in correction; Then use the inventive method to estimate degree of unbalancedness and each channels crosstalk, correct test point by estimated value equally, the results are shown in Table 3 in correction; Scattering matrix restorability due to test target depends on the estimated accuracy of calibrating method to degree of unbalancedness and each channels crosstalk, the correction result of test target scattering matrix listed in table 2 and table 3, compared to the recovery degree of theoretical value, can illustrate the estimated accuracy to degree of unbalancedness and each channels crosstalk of two kinds of methods.

After contrast table 2 and table 3 can find to adopt technical scheme of the present invention, scattering matrix cross aisle component after each trihedral angle test target restores declines than employing prior art, fall is maximum can up to 12dB, thus closer to theoretical value, (theoretical value is 0, i.e.-∞ dB), the phase value of same polarization passage also more levels off to theoretical value (theoretical value is 1, i.e. 0dB) than prior art; For dihedral angle test target, the scattering matrix that employing the inventive method obtains is also more close to theoretical value.Comprehensive above-mentioned experimental result can illustrate, the beneficial effect of the inventive method.

Table 1 scaler scattering matrix theory value

Test point scattering matrix the calibration results is obtained under table 2 prior art

Test point scattering matrix the calibration results is obtained under table 3 the inventive method

The above; be only the embodiment in the present invention, but protection scope of the present invention is not limited thereto, any people being familiar with this technology is in the technical scope disclosed by the present invention; the conversion or replacement expected can be understood, all should be encompassed in of the present invention comprising within scope.

Claims (5)

1., based on the polarimetric calibration method that platform stance time variation compensates, it is characterized in that, comprise the following steps:

Step S1: the raw radar data of four POLARIZATION CHANNEL obtained from the polarimetric synthetic aperture radar system be loaded into platform carries out distance to compression, and range migration correction process and interchannel registration process, obtain two-dimentional echo data;

Step S2: according to the synthetic aperture time-parameters of scaler orientation to coordinate and polarimetric synthetic aperture radar system, and from two-dimentional echo data, extracts the scattering matrix observed reading M (η) of scaler at same irradiation moment η;

Step S3: utilize scaler orientation to and distance to coordinate, and polarimetric synthetic aperture radar system irradiation low coverage and flying height parameter, calculate incident angle φ and the angle of squint θ of electromagnetic wave irradiation scaler _sq;

Step S4: utilize platform flight attitude data, incident angle φ and angle of squint θ _sq, amount of deflection θ (η) model representation calculating each irradiation moment η scaler reception polarization of ele orientation angle is as follows:

$\tan \mathrm{\θ}\left(\mathrm{\η}\right)=\frac{\sin \mathrm{\φ}\sin {\mathrm{\θ}}_p-\cos \mathrm{\φ}\cos {\mathrm{\θ}}_p\sin {\mathrm{\θ}}_y}{\cos {\mathrm{\θ}}_{\mathrm{sq}}\cos {\mathrm{\θ}}_p\cos {\mathrm{\θ}}_y-\sin {\mathrm{\θ}}_{\mathrm{sq}}(\cos \mathrm{\φ}\sin {\mathrm{\θ}}_p+\sin \mathrm{\φ}\cos {\mathrm{\θ}}_p\sin {\mathrm{\θ}}_y)}$

θ in above formula _pit is the pitching angle theta with irradiation time η change _p(η) reduced representation, θ _ythe crab angle θ with irradiation time η change _y(η) reduced representation; θ _sqthe antenna relative calibration device angle of squint θ with irradiation time η change _sq(η) reduced representation, φ represents the incident angle of electromagnetic wave irradiation scaler; In above-mentioned, θ _p, θ _ychange with irradiation time feature attitude time become feature, θ _sqfeature the coupling influence of antenna angle of squint;

Step S5: utilize scaler to receive the amount of deflection of polarization of ele orientation angle, carry out amount of deflection correction to scattering matrix observed reading M (η), obtains the complete polarization echo data after compensation of attitude error correction;

Step S6: orientation is carried out to compression to the complete polarization echo data after compensation of attitude error corrects, obtains image;

Step S7: in each POLARIZATION CHANNEL of image, extract the scattering matrix after the correction of scaler amount of deflection, adopt the Whitt algorithm carrying out scene calibration based on scaler, to remain in scaler amount of deflection correct after scattering matrix in, the degree of unbalancedness introduced by polarimetric synthetic aperture radar systems radiate and receiver module and each channels crosstalk estimate, realize polarimetric synthetic aperture radar Systematic Error Correction, obtain polarimetric synthetic aperture radar image.

2. as claimed in claim 1 based on the polarimetric calibration method that platform stance time variation compensates, it is characterized in that, described scattering matrix observed reading M (η) is by extracting the same orientation of scaler to irradiating four POLARIZATION CHANNEL echo data m corresponding to moment η in synthetic aperture time range _hh(η), m _hv(η), m _vh(η), m _vv(η), four groups of echo datas are formed scattering matrix observed reading M (η) with following form:

$M\left(\mathrm{\η}\right)=\left[\begin{array}{cc}{m}_{\mathrm{hh}}\left(\mathrm{\η}\right)& m_{\mathrm{hv}}\left(\mathrm{\η}\right)\\ m_{\mathrm{vh}}\left(\mathrm{\η}\right)& m_{\mathrm{vv}}\left(\mathrm{\η}\right)\end{array}\right].$

3. as claimed in claim 1 based on the polarimetric calibration method that platform stance time variation compensates, it is characterized in that, described platform flight attitude data comprise the crab angle θ with irradiation time η change _y(η), pitching angle theta _p(η) with roll angle θ _r(η).

4. as claimed in claim 1 based on the polarimetric calibration method that platform stance time variation compensates, it is characterized in that, build the model S of the scattering matrix after the correction of scaler amount of deflection _{θ _ comp}(η), S _{θ _ comp}(η) be expressed as follows:

S _{θ_comp}(η)＝D ^-1[θ(η)]·M(η)·D[θ(η)]

Wherein, irradiate moment η polarization orientation angle deflection matrix D [θ (η)] to be expressed as:

$D\left[\mathrm{\θ}\left(\mathrm{\η}\right)\right]=\left[\begin{array}{cc}\cos \mathrm{\θ}\left(\mathrm{\η}\right)& -\sin \mathrm{\θ}\left(\mathrm{\η}\right)\\ \sin \mathrm{\θ}\left(\mathrm{\η}\right)& \cos \mathrm{\θ}\left(\mathrm{\η}\right)\end{array}\right],$

D ^-1[θ (η)] is inverse matrix,

S _{θ _ comp}(η) in, element is scaler in each POLARIZATION CHANNEL, is irradiating the complete polarization echo data that corresponding to moment η, polarization rotation amount corrects.

5., as claimed in claim 1 based on the polarimetric calibration method that platform stance time variation compensates, it is characterized in that, described platform flight attitude data have time variation in scaler irradiation time.