CN104181530A - Determination method and device for polarization isolation index - Google Patents

Abstract

The invention discloses a determination method for a polarization isolation index. The method includes the following steps: generating a reference scattering matrix according to SAR data of an identical waveband in an airborne multi-polarization synthetic aperture radar (SAR) system and a satellite-borne multi-polarization SAR system; adding crosstalks and noises of different isolations in the reference scattering matrix so that a measurement scattering matrix is generated; and according to the reference scattering matrix and the measurement scattering matrix, determining the polarization isolation index in the satellite-borne multi-polarization SAR system under different application demands. The invention also discloses a determination device for the polarization isolation index.

Description

A kind of polarization isolation Index and device

Technical field

The present invention relates to synthetic-aperture radar (SAR, Synthetic Aperture Radar) technical field, relate in particular to a kind of polarization isolation Index and device.

Background technology

SAR is the active microwave imaging radar of a kind of high resolving power, can use shorter antenna obtain higher distance to and azimuth resolution.SAR is divided into again multipolarization SAR and single polarization SAR according to the difference of polarization mode; Multipolarization SAR can obtain the multipolarization information of target, and physical property that target is more complete and meticulousr structural information are provided, and improves the precision to target polarization characteristic parameter extraction and ground object target classification, improves the probability to object detection and recognition.Multipolarization SAR and single polarization SAR can be subdivided into again spaceborne multipolarization SAR, airborne multipolarization SAR and spaceborne single polarization SAR, airborne single polarization SAR; Wherein, spaceborne multipolarization SAR estimates in Ocean monitoring, environmental disaster control and assessment, land mapping, urban development planning, Crop classification and grain yield, the aspect such as Dynamic Monitoring of Forest Resources, military target supervision has important using value.The performance of spaceborne multipolarization SAR will directly affect picture quality and subsequent applications.

Spaceborne multipolarization SAR system mainly comprises the parameter designing such as frequency, orbit parameter, geometric parameter, radar parameter.Wherein, radar parameter is one of key parameter in spaceborne multipolarization SAR system.In all radar parameters, polarization correlation parameter is again that spaceborne multipolarization SAR system is peculiar and vital with respect to spaceborne single polarization SAR system.Too high polarization correlation parameter index request can cause spaceborne multipolarization SAR the Hardware Design to be difficult to realize, otherwise can cause the Polarimetric SAR Image difficult quality of spaceborne multipolarization SAR system acquisition to meet user demand.Polarization isolation is exactly so extremely important index in spaceborne multipolarization SAR system.The existing a large amount of experience of single polarization SAR system can be followed, as having, the parameters such as pulse repetition rate (PRF, Pulse Recurrence Frequency), mapping bandwidth, resolution, range ambiguity and azimuth ambiguity design a model in a large number and design experiences.Although multipolarization SAR system model has comprised the noise NE σ relevant to system sensitivity ⁰with the polarization isolation parameter such as crosstalk, but can not directly design polarization isolation index by this system model.Meanwhile, polarization isolation index is subject to again system sensitivity Index Influence, and this also can increase the complicacy of system polarization isolation index demand analysis.

China's airborne multipolarization SAR system is widely used, and some airborne multipolarization SAR system dual-mode antenna splits, and can realize very high isolation index, can be better than 45dB, and the impact that polarization is crosstalked is very little.But dual-mode antenna splits and in spaceborne multipolarization SAR system, is difficult to realize.Too high isolation index has proposed very high technology Design and implementation requirement to spaceborne multipolarization SAR system antenna etc., is sometimes even difficult to realize.According to application demand, the spaceborne multipolarization SAR of appropriate design systematic technical indicator will be avoided the unnecessary wasting of resources, shortens the lead time, is conducive to the development and application of Chinese spaceborne multipolarization SAR system.

Summary of the invention

The problem existing for solving prior art, the embodiment of the present invention is expected to provide a kind of polarization isolation Index and device, can be according to application demand, the polarization isolation index of the spaceborne multipolarization SAR of appropriate design system.

Technical scheme of the present invention is achieved in that

The embodiment of the present invention provides a kind of polarization isolation Index, and described method comprises:

According in airborne multi polarized SAR SAR system with the SAR data generating reference scattering matrix of the identical wave band of spaceborne multipolarization SAR system; Add different isolations to crosstalk and noise described in reference to scattering matrix, generate and measure scattering matrix; Determine the polarization isolation index in spaceborne multipolarization SAR system under different application demand according to described with reference to scattering matrix and measurement scattering matrix.

In such scheme, described polarization SAR data refer to the scatter echo matrix S of ground object target in xy POLARIZATION CHANNEL _xy; Wherein, x represents to launch polarization mode, and y represents to receive polarization mode, and the value of xy POLARIZATION CHANNEL is horizontal polarization mode h or vertical polarization mode v.

In such scheme, the reference scattering matrix S of described generation _r, for:

$S_R=\left(\begin{array}{cc}{S}_{\mathrm{vv}}^R& S_{\mathrm{vh}}^R\\ S_{\mathrm{hv}}^R& S_{\mathrm{hh}}^R\end{array}\right),$

Wherein, S _xythe scatter echo signal that represents ground object target in xy POLARIZATION CHANNEL, x represents to launch polarization mode, and y represents to receive polarization mode; The value of xy POLARIZATION CHANNEL is horizontal polarization mode h or vertical polarization mode v.

In such scheme, scattering matrix is measured in described generation, comprising:

Determine the polarization isolation that will the add δ that crosstalks ₁, δ ₂, δ ₃δ _n;

Determine the noise NE σ that will add ⁰ ₁, NE σ ⁰ ₂, NE σ ⁰ ₃nE σ ⁰ _m;

At S _rmiddlely add respectively a polarization isolation to crosstalk and a noise, generates n × m measurement scattering matrix M.

In such scheme, described measurement scattering matrix M is:

$M=\left(\begin{array}{cc}1& \mathrm{\δ}\\ \mathrm{\δ}& 1\end{array}\right)\left(\begin{array}{cc}{S}_{\mathrm{vv}}^R& S_{\mathrm{vh}}^R\\ S_{\mathrm{hv}}^R& S_{\mathrm{hh}}^R\end{array}\right)\left(\begin{array}{cc}1& \mathrm{\δ}\\ \mathrm{\δ}& 1\end{array}\right)+N,$

Wherein, δ represents that polarization isolation crosstalks; N is noise gain matrix; S _xythe scatter echo signal that represents ground object target in xy POLARIZATION CHANNEL, x represents to launch polarization mode, and y represents to receive polarization mode; The value of xy POLARIZATION CHANNEL is horizontal polarization mode h or vertical polarization mode v.

In such scheme, the crosstalk pass of δ of described polarization isolation index C and polarization isolation is:

C＝-20×log10(δ)。

In such scheme, described according to described measurement scattering matrix M with reference to scattering matrix S _rdetermine the polarization isolation index in spaceborne multipolarization SAR system under respective application demand, comprising:

Determine described measurement scattering matrix M and with reference to scattering matrix S _rmiddle noise NE σ ⁰to corresponding spaceborne multipolarization SAR system applies demand parameter influence degree;

According to NE σ ⁰to the influence degree demand of spaceborne multipolarization SAR system applies demand parameter, determine NE σ ⁰;

Analyze described definite NE σ ⁰under, the influence degree of polarization isolation index C to corresponding spaceborne multipolarization SAR system applies demand parameter, determines the polarization isolation index C under respective application demand.

In such scheme, described respective application demand, comprising: polarization isolation index C decomposes terrain classification Accuracy degree demand and/or verification and measurement ratio influence degree demand and/or the polarization isolation index C influence degree demand to quality factor of polarization isolation index C to target detection to H/Alpha.

The embodiment of the present invention provides a kind of polarization isolation index determining device, and described device comprises: with reference to scattering matrix generation module, measurement scattering matrix generation module and polarization isolation index determination module; Wherein,

Described with reference to scattering matrix generation module, for the SAR data generating reference scattering matrix with the identical wave band of spaceborne multipolarization SAR system according to airborne synthetic aperture radar SAR system;

Described measurement scattering matrix generation module, for adding different isolations to crosstalk and noise described with reference to scattering matrix, generates and measures scattering matrix;

Described polarization isolation index determination module, for according to described with reference to scattering matrix with measure scattering matrix and determine the polarization isolation index of spaceborne multipolarization SAR system under different application demand.

In such scheme, described polarization SAR data refer to the scatter echo matrix S of ground object target in xy POLARIZATION CHANNEL _xy; Wherein, x represents to launch polarization mode, and y represents to receive polarization mode, and the value of xy POLARIZATION CHANNEL is horizontal polarization mode h or vertical polarization mode v.

In such scheme, the reference scattering matrix S of described generation _r, for:

$S_R=\left(\begin{array}{cc}{S}_{\mathrm{vv}}^R& S_{\mathrm{vh}}^R\\ S_{\mathrm{hv}}^R& S_{\mathrm{hh}}^R\end{array}\right),$

Wherein, S _xythe scatter echo signal that represents ground object target in xy POLARIZATION CHANNEL, x represents to launch polarization mode, and y represents to receive polarization mode; The value of xy POLARIZATION CHANNEL is horizontal polarization mode h or vertical polarization mode v.

In such scheme, described measurement scattering matrix generation module adds different isolations to crosstalk and noise described in reference to scattering matrix, generates to measure scattering matrix and generate and measure scattering matrix, comprising:

Determine the polarization isolation that will the add δ that crosstalks ₁, δ ₂, δ ₃δ _n;

Determine the noise NE σ that will add ⁰ ₁, NE σ ⁰ ₂, NE σ ⁰ ₃nE σ ⁰ _m;

At S _rmiddlely add respectively a polarization isolation to crosstalk and a noise, generates n × m measurement scattering matrix M.

In such scheme, the measurement scattering matrix M of described generation, for:

$M=\left(\begin{array}{cc}1& \mathrm{\δ}\\ \mathrm{\δ}& 1\end{array}\right)\left(\begin{array}{cc}{S}_{\mathrm{vv}}^R& S_{\mathrm{vh}}^R\\ S_{\mathrm{hv}}^R& S_{\mathrm{hh}}^R\end{array}\right)\left(\begin{array}{cc}1& \mathrm{\δ}\\ \mathrm{\δ}& 1\end{array}\right)+N,$

Wherein, δ represents that polarization isolation crosstalks; N is noise gain matrix; S _xythe scatter echo signal that represents ground object target in xy POLARIZATION CHANNEL, x represents to launch polarization mode, and y represents to receive polarization mode; The value of xy POLARIZATION CHANNEL is horizontal polarization mode h or vertical polarization mode v.

In such scheme, the crosstalk pass of δ of described polarization isolation index C and polarization isolation is:

C＝-20×log10(δ)。

In such scheme, described polarization isolation index determination module is determined the polarization isolation index in spaceborne multipolarization SAR system under different application demand according to described with reference to scattering matrix and measurement scattering matrix, comprising:

Determine described measurement scattering matrix M and with reference to scattering matrix S _rmiddle noise NE σ ⁰to the influence degree of corresponding spaceborne multipolarization SAR system applies demand parameter;

According to NE σ ⁰to the influence degree demand of spaceborne multipolarization SAR system applies demand parameter, determine NE σ ⁰;

Analyze described definite NE σ ⁰under, polarization isolation index C, to corresponding spaceborne multipolarization SAR system applies demand parameter influence degree, determines the polarization isolation index C index under respective application demand.

In such scheme, described respective application demand, comprising: polarization isolation index C decomposes terrain classification Accuracy degree demand and/or verification and measurement ratio influence degree demand and/or the polarization isolation index C influence degree demand to quality factor of polarization isolation index C to target detection to H/Alpha.

Polarization isolation Index and device that the embodiment of the present invention provides, according in airborne multipolarization SAR system with the SAR data generating reference scattering matrix of the identical wave band of spaceborne multipolarization SAR system; Add different isolations to crosstalk and noise described in reference to scattering matrix, generate and measure scattering matrix; Determine the polarization isolation index in spaceborne multipolarization SAR system under different application demand according to described with reference to scattering matrix and measurement scattering matrix; So, utilize the impact of the airborne multipolarization SAR of existing high-isolation data analysis polarization isolation on spaceborne multipolarization SAR market demand, carry out the demand analysis of spaceborne multipolarization SAR isolation of system degree, design and definite, thereby promote the Design and implementation of spaceborne multipolarization SAR system.

Brief description of the drawings

The schematic flow sheet of the polarization isolation Index that Fig. 1 provides for the embodiment of the present invention;

Fig. 2 is polarization isolation and the influence degree curve map of noise to H/Alpha classification results;

Fig. 3 is the verification and measurement ratio of polarization isolation to target detection and the influence curve figure of quality factor;

The structural representation of the polarization isolation index determining device that Fig. 4 provides for the embodiment of the present invention.

Embodiment

In the embodiment of the present invention, according in airborne multipolarization SAR system with the SAR data generating reference scattering matrix of the identical wave band of spaceborne multipolarization SAR system; Add different isolations to crosstalk and noise described in reference to scattering matrix, generate and measure scattering matrix; Determine the polarization isolation index in spaceborne multipolarization SAR system under different application demand according to described with reference to scattering matrix and measurement scattering matrix.

Below by drawings and the specific embodiments, the present invention is described in further detail.

The embodiment of the present invention realizes a kind of polarization isolation Index, and as shown in Figure 1, the method comprises following step:

Step 101: according in airborne multipolarization SAR system with the SAR data generating reference scattering matrix of the identical wave band of spaceborne multipolarization SAR system;

Concrete, how to obtain in airborne multipolarization SAR system and belong to prior art with the polarization SAR data of the identical wave band of spaceborne multipolarization SAR system, repeat no more here;

After described airborne multipolarization SAR data acquisition success, can directly transfer to the signal processor processes of spaceborne multipolarization SAR internal system, or process by any equipment that possesses data-handling capacity;

Concrete, described polarization SAR data refer to the scatter echo matrix S of ground object target in xy POLARIZATION CHANNEL _xy, wherein, x represents to launch polarization mode, and y represents to receive polarization mode; The value of xy POLARIZATION CHANNEL can be horizontal polarization mode h or vertical polarization mode v;

Concrete, according to described polarization SAR data S _xygenerating reference scattering matrix S _r, S _rconcrete representation as follows:

$S_R=\left(\begin{array}{cc}{S}_{\mathrm{vv}}^R& S_{\mathrm{vh}}^R\\ S_{\mathrm{hv}}^R& S_{\mathrm{hh}}^R\end{array}\right)---\left(1\right)$

Wherein, S _xythe scatter echo matrix that represents ground object target in xy POLARIZATION CHANNEL, x represents to launch polarization mode, and y represents to receive polarization mode; The value of xy POLARIZATION CHANNEL can be horizontal polarization mode h or vertical polarization mode v, for example, middle x POLARIZATION CHANNEL and y POLARIZATION CHANNEL are vertical polarization mode; middle x POLARIZATION CHANNEL is vertical polarization mode, and y POLARIZATION CHANNEL is horizontal polarization mode;

Step 102: add different polarization isolations to crosstalk and noise described in reference to scattering matrix, generate corresponding measurement scattering matrix;

Described with reference to scattering matrix S _rin add different polarization isolations to crosstalk and noise NE σ ⁰after, the measurement scattering matrix M of generation is:

$M=\left(\begin{array}{cc}1& \mathrm{\δ}\\ \mathrm{\δ}& 1\end{array}\right)\left(\begin{array}{cc}{S}_{\mathrm{vv}}^R& S_{\mathrm{vh}}^R\\ S_{\mathrm{hv}}^R& S_{\mathrm{hh}}^R\end{array}\right)\left(\begin{array}{cc}1& \mathrm{\δ}\\ \mathrm{\δ}& 1\end{array}\right)+N---\left(2\right)$

Wherein, δ represents that polarization isolation crosstalks; S _xythe scatter echo signal that represents ground object target in xy POLARIZATION CHANNEL, x represents to launch polarization mode, and y represents to receive polarization mode, and the value of xy POLARIZATION CHANNEL can be horizontal polarization mode h or vertical polarization mode v, for example, middle x POLARIZATION CHANNEL and y POLARIZATION CHANNEL are vertical polarization mode; middle x POLARIZATION CHANNEL is vertical polarization mode, and y POLARIZATION CHANNEL is horizontal polarization mode; N is noise gain matrix, concrete, $N=\left(\begin{array}{cc}{n}_{\mathrm{vv}}& n_{\mathrm{vh}}\\ n_{\mathrm{hv}}& n_{\mathrm{hh}}\end{array}\right);$ Wherein, n _xythe scatter echo signal that represents xy POLARIZATION CHANNEL target, x represents to launch polarization mode, and y represents to receive polarization mode; The value of xy POLARIZATION CHANNEL can be horizontal polarization h and vertical polarization v, for example, and n _vvmiddle x POLARIZATION CHANNEL and y POLARIZATION CHANNEL are vertical polarization; n _vhmiddle x POLARIZATION CHANNEL is vertical polarization, and y POLARIZATION CHANNEL is horizontal polarization;

Here the method that generates measurement scattering matrix M is specially:

Determine the polarization isolation that will the add δ that crosstalks ₁, δ ₂, δ ₃δ _n;

Determine the noise NE σ that will add ⁰ ₁, NE σ ⁰ ₂, NE σ ⁰ ₃nE σ ⁰ _m;

Add respectively a polarization isolation to crosstalk and a noise, generate and measure scattering matrix M;

Like this, the number of the final measurement scattering matrix M generating of the embodiment of the present invention is individual; That is to say, in the embodiment of the present invention, n polarization isolation crosstalked and m noise is to add in pairs with reference in scattering matrix, thereby generates n × m measurement scattering matrix M;

If the measurement scattering matrix of all generations, with matrix representation, can be expressed as to form:

$\left[\begin{array}{ccccc}{M}_{11}& M_{12}& M_{13}& ...& M_{1n}\\ M_{21}& M_{22}& M_{23}& ...& M_{2n}\\ M_{31}& M_{32}& M_{33}& ...& M_{3n}\\ ...& ...& ...& ...& ...\\ M_{m1}& M_{m2}& M_{m3}& ...& M_{\mathrm{mn}}\end{array}\right],$

Wherein, each matrix is with M _xyunity of form represent, M _xybe illustrated in S _rin add x isolation crosstalk and y noise after the measurement scattering matrix that generates;

In this step, the polarization isolation that the add δ that crosstalks ₁, δ ₂, δ ₃δ _n, and the noise NE σ that will add ⁰ ₁, NE σ ⁰ ₂, NE σ ⁰ ₃nE σ ⁰ _min the time that determining, reality can choose as required; Conventionally, the effective span of theory that polarization isolation is crosstalked is :-40dB～-15dB, noise NE σ ⁰the effective span of theory be :-30dB～-19dB, therefore, a kind of exemplary value scheme is: determine that according to the fine degree of the definite polarization isolation index of hope the polarization isolation that will add crosstalks and noise, for example, if higher to polarization isolation index accuracy requirement to be determined, can crosstalk at polarization isolation relative some more, exemplary with value in the theoretical valid value range of noise, can quantize with interval 1dB; If lower to polarization isolation index accuracy requirement to be determined, can be polarization isolation crosstalk relative with value in the theoretical valid value range of noise less (namely by spaced value relatively large), exemplary, can will be set to 3dB, 4dB etc.; Another kind of exemplary value scheme is: interval is arranged in the effective span of above-mentioned theory, that is to say, the end points of interval is between two end points of the effective value of theory, like this, user can be only to self high region of care degree doing explication de texte, thereby determine polarization isolation index, and can crosstalk and the relative concentrated area of noise according to the pre-determined polarization isolation of any needs for user in the high region of so-called care degree; Another exemplary value scheme is: in the span of theoretical effective value, in the high region of care degree by spaced value less, and in the lower region of care degree by spaced value larger; What user can give priority to like this crosstalks and with noise, the impact with reference to scattering matrix is analyzed isolation.

Concrete, (2) formula can obtain by following derivation:

Conventionally, the system model of the measurement matrix of multipolarization SAR aims of systems can represent by (3) formula, and the spaceborne multipolarization SAR system in the embodiment of the present invention is also followed this system model:

Wherein, M represents the atural object polarization scattering matrix that multipolarization SAR measures;

Concrete, $M=\left(\begin{array}{cc}{M}_{\mathrm{vv}}& M_{\mathrm{vh}}\\ M_{\mathrm{hv}}& M_{\mathrm{hh}}\end{array}\right);$ Wherein, M _xyrepresent the atural object Polarization scattering signal of xy POLARIZATION CHANNEL; X represents to launch polarization mode, and y represents to receive polarization mode; The value of xy POLARIZATION CHANNEL can be horizontal polarization h and vertical polarization v, for example, and M _vvmiddle x POLARIZATION CHANNEL and y POLARIZATION CHANNEL are vertical polarization; M _vhmiddle x POLARIZATION CHANNEL is vertical polarization, and y POLARIZATION CHANNEL is horizontal polarization;

S represents the true polarization scattering matrix of multipolarization SAR ground object target: $S=\left(\begin{array}{cc}{S}_{\mathrm{vv}}& S_{\mathrm{vh}}\\ S_{\mathrm{hv}}& S_{\mathrm{hh}}\end{array}\right);$

A represents the absolute amplitude gain factor that multipolarization SAR system is total; A is total absolute amplitude gain factor, does not affect the relativeness between M and s-matrix, can omit.

φ represents multipolarization SAR system phase shift (absolute phase), comprises likely and originating, for example the impact of transmitter, receiver, SAR correlator; Due to this phase bit loss in multipolarization is synthetic, therefore can not consider;

R represents that multipolarization SAR system receives distortion matrix; Concrete, $R=\left(\begin{array}{cc}1& \mathrm{\δ}1\\ \mathrm{\δ}2& f_1\end{array}\right),$ Wherein, polarization isolation when δ 1 represents to receive H polarized wave crosstalk (the shared ratio of V polar component of sneaking into); Polarization isolation when δ 2 represents to receive V polarized wave crosstalk (the shared ratio of H polar component of sneaking into); f ₁represent the degree of unbalancedness (comprising amplitude and phase place) between receiving cable;

T represents multipolarization radar emission distortion matrix; $T=\left(\begin{array}{cc}1& \mathrm{\δ}3\\ \mathrm{\δ}4& f_2\end{array}\right),$ Wherein, polarization isolation when δ 3 represents transmitting H polarized wave is crosstalked; Polarization isolation when δ 4 represents transmitting V polarized wave is crosstalked;

F ₂represent the degree of unbalancedness (comprising amplitude and phase place) between transmission channel;

N represents noise gain matrix, concrete, $N=\left(\begin{array}{cc}{n}_{\mathrm{vv}}& n_{\mathrm{vh}}\\ n_{\mathrm{hv}}& n_{\mathrm{hh}}\end{array}\right);$ Wherein, n _xythe scatter echo signal that represents xy POLARIZATION CHANNEL target, x represents to launch polarization mode, and y represents to receive polarization mode; The value of xy POLARIZATION CHANNEL can be horizontal polarization h and vertical polarization v, for example, and n _vvmiddle x POLARIZATION CHANNEL and y POLARIZATION CHANNEL are vertical polarization; n _vhmiddle x POLARIZATION CHANNEL is vertical polarization, and y POLARIZATION CHANNEL is horizontal polarization;

S _xyrepresent the scatter echo signal of xy POLARIZATION CHANNEL target;

For investigating separately the impact of polarization isolation on Polarimetric SAR Image application, in same multipolarization SAR system, ignoring channel imbalance degree affects f ₁=f ₂=1, and suppose δ 1=δ 2=δ 3=δ 4=δ, the relation of measuring between the reference scattering matrix S of scattering matrix M and target is reduced to (2) formula.

Step 103: determine the polarization isolation index in spaceborne multipolarization SAR system under respective application demand with reference to scattering matrix and measurement scattering matrix according to described;

In the embodiment of the present invention, need definite polarization isolation index C to calculate by the δ that crosstalks of the polarization isolation in formula (2), concrete:

C＝-20×log10(δ) (4)

First, according to measurement scattering matrix M definite in step 102 with reference to scattering matrix S _rdetermine polarization isolation and the noise influence degree to H/Alpha classification results, select the polarization isolation reference value of crosstalking for-40dB ,-35dB ,-30dB ,-25dB ,-20dB ,-15dB ,-10dB; Select the reference value of noise be-19dB ,-22dB ,-24dB ,-26dB ,-28dB and-30dB; , to the influence degree curve of H/Alpha classification results as shown in Figure 2, in figure, transverse axis represents isolation for described polarization isolation and noise, and unit is dB; The longitudinal axis represents classification results accuracy, classification results influence degree (%)=1-classification results accuracy (%); As can be seen from Figure 2, NE σ ⁰when fixing, polarization isolation C is less than 0.1% to the impact of atural object classification results within the scope of-45dB～-20dB.And polarization isolation C is when fixing, NE σ ⁰within the scope of 19dB～30dB, the influence degree of atural object classification results is about to 1%; Visible, NE σ ⁰larger on the application result impact of polarization SAR data than polarization isolation C, therefore can reach a conclusion: in the time of spaceborne multipolarization SAR system, should first determine NE σ ⁰, then determine polarization isolation C;

Therefore, the embodiment of the present invention is carried out determining of polarization isolation index C from described conclusion;

Concrete, described according to described measurement scattering matrix M with reference to scattering matrix S _rdetermine the polarization isolation index C in spaceborne multipolarization SAR system under respective application demand, comprising:

Determine described measurement scattering matrix M and with reference to scattering matrix S _rmiddle noise NE σ ⁰to the influence degree of corresponding spaceborne multipolarization SAR system applies demand parameter;

Analyze described definite NE σ ⁰under, polarization isolation index C, to corresponding spaceborne multipolarization SAR system applies demand parameter influence degree, determines the polarization isolation index C under respective application demand;

Concrete, described respective application demand refers to the influence degree demand of polarization isolation index C to spaceborne multipolarization SAR system applies demand parameter, comprises following one of them kind or combination in any: polarization isolation index C is the verification and measurement ratio influence degree demand to target detection, polarization isolation index C influence degree demand to quality factor etc. to H/Alpha decomposition terrain classification Accuracy degree demand, polarization isolation index C; Wherein, application demand index refers to: H/Alpha decomposes verification and measurement ratio, quality factor of terrain classification precision, target detection etc.; It should be noted that, only provide some conventional application demand indexs here; Because the application demand index relating in spaceborne multipolarization SAR system is numerous, the influence degree demand according to isolation to different system application demand index, the polarization isolation index C determining is also just different.

Concrete, can determine described measurement scattering matrix M and with reference to scattering matrix S by following steps _rmiddle noise NE σ ⁰influence degree to corresponding spaceborne multipolarization SAR system applies demand parameter:

The first step: calculate with reference to scattering matrix S _rresult under different application demand, is designated as reference value std;

Second step: calculate respectively foregoing m*n and measure scattering matrix:

$\left[\begin{array}{ccccc}{M}_{11}& M_{12}& M_{13}& ...& M_{1n}\\ M_{21}& M_{22}& M_{23}& ...& M_{2n}\\ M_{31}& M_{32}& M_{33}& ...& M_{3n}\\ ...& ...& ...& ...& ...\\ M_{m1}& M_{m2}& M_{m3}& ...& M_{\mathrm{mn}}\end{array}\right]$

In the result of each M under different application demand, be designated as measured value Y _cmn; Wherein, subscript c represents different application demands.

Wherein, the polarization isolation value of crosstalking is foregoing: δ ₁, δ ₂, δ ₃δ _n;

NE σ ⁰noise value is foregoing: NE σ ⁰ ₁, NE σ ⁰ ₂, NE σ ⁰ ₃nE σ ⁰ _m;

The 3rd step: for every kind of application demand, calculate respectively different noise NE σ in the time that δ is different fixed value ⁰corresponding Y _cmn-std, the result obtaining is noise NE σ under certain δ fixed value ⁰to the influence degree of corresponding spaceborne multipolarization SAR system applies demand parameter, in actual applications, the result obtaining can be depicted as to curve map as shown in Figure 2, thereby data are analyzed more intuitively.

The 4th step: according to NE σ ⁰to spaceborne multipolarization SAR system applies demand parameter influence degree, determine the NE σ under respective application demand ⁰.

Further, as the NE σ under respective application demand ⁰after determining, as long as to described definite NE σ ⁰lower polarization isolation C analyzes the influence degree of corresponding spaceborne multipolarization SAR system applies demand parameter, just can determine the polarization isolation index C under respective application demand.

Embodiment mono-

Below by emulation experiment, the method described in above-mentioned steps 101-step 103 is introduced;

In experiment, using the on-board SAR image data of high polarization isolation index as input, the application demand arranging in experiment comprises: 1, noise NE σ ⁰h/Alpha is decomposed to terrain classification Accuracy and be not more than 2%; 2,, when meeting application demand 1, polarization isolation index C decomposes terrain classification Accuracy to H/Alpha and is not more than 2%; Polarization isolation index C is not more than 15% to the verification and measurement ratio impact of target detection, and the impact of quality factor is not more than to 25%.

The emulation experiment of the embodiment of the present invention one comprises the following steps:

Step 301: determine with reference to scattering matrix S according to the on-board SAR image data of described input _r, concrete, S _rdefinite method belong to prior art, repeat no more here;

Step 302: at S _rin the polarization isolation that adds crosstalk and noise generating reference scattering matrix M;

A) emulation polarization isolation is crosstalked

Conventionally, the effective span of theory that polarization isolation is crosstalked is :-40dB～-15dB, and therefore, in experiment, selecting the reference value that polarization isolation is crosstalked is 40dB, 35dB, 30dB, 28dB, 25dB, 20dB, 15dB;

The polarization isolation of being tried to achieve under corresponding polarization isolation by (3) formula is crosstalked in δ substitution (2) formula.

B) simulator and noise

Noise NE σ ⁰the effective span of theory be :-30dB～-19dB, therefore, the reference value of selecting utmost point noise in experiment for-19dB ,-22dB ,-24dB ,-26dB ,-28dB and-30dB;

Next, by noise NE σ ⁰determine corresponding noise matrix N; Here, by NE σ ⁰the concrete methods of realizing of determining N belongs to prior art, repeats no more here;

To in definite N substitution formula (2), obtain measuring scattering matrix M;

Step 303: determine the polarization isolation index in spaceborne multipolarization SAR system under respective application demand with reference to scattering matrix and measurement scattering matrix according to described;

First, according to application demand, can adopt H/Alpha decompose the analysis to measure scattering matrix M such as terrain classification method or PWF filtering+CFAR CFAR object detection method or target Similarity Parameter object detection method with reference to scattering matrix S _rterrain classification and target detection resultant error, obtain the graph of errors of measured value relative reference result, this curve as shown in Figure 2.

Afterwards, determine the polarization isolation index C demand in spaceborne multipolarization SAR system under respective application demand, comprise the following steps:

Step 1: first determine and meet NE σ ⁰h/Alpha is decomposed to terrain classification Accuracy and be not more than 2% NE σ ⁰value; As seen from Figure 2, need NE σ ⁰be better than-22dB.

Step 2: when meeting application demand 1, meet polarization isolation index C and H/Alpha is decomposed to terrain classification Accuracy be not more than 2%, as can be seen from Figure 2, polarization isolation index C should be better than 22dB; To meet on this basis verification and measurement ratio and the quality factor impact of polarization isolation index C on target detection and be not more than respectively 15% and 25%, first determine NE σ ⁰when=-22dB, the verification and measurement ratio of polarization isolation index to target detection and the influence curve of quality factor, described curve as shown in Figure 3, curve shown in broken lines represents the verification and measurement ratio influence curve of polarization isolation index to target detection, represent the influence curve of polarization isolation index to quality factor with the curve shown in solid line, transverse axis represents polarization isolation index, and the longitudinal axis represents that the number percent of influence degree is converted to the numerical value after decimal; As can be seen from Figure 3, polarization isolation index C is not more than 15% and when impact is not more than 25% on quality factor, the polarization isolation index C of system should be 28dB～30dB to the verification and measurement ratio impact of target detection.

Step 3: consider the result of step 1 and step 2, finally determine the NE σ of system ⁰be better than-22dB, polarization isolation index C is better than 30dB.

In order to realize said method, the embodiment of the present invention also provides a kind of polarization isolation index determining device, as shown in Figure 4, described device comprises: with reference to scattering matrix generation module 41, measurement scattering matrix generation module 42 and polarization isolation index determination module 43; Wherein,

Described with reference to scattering matrix generation module 41, for the SAR data generating reference scattering matrix with the identical wave band of spaceborne multipolarization SAR system according to airborne synthetic aperture radar SAR system;

Described measurement scattering matrix generation module 42, for adding different isolations to crosstalk and noise described with reference to scattering matrix, generates and measures scattering matrix;

Described polarization isolation index determination module 43, for according to described with reference to scattering matrix with measure scattering matrix and determine the polarization isolation index of spaceborne multipolarization SAR system under different application demand.

Concrete, described polarization SAR data refer to the scatter echo matrix S of ground object target in xy POLARIZATION CHANNEL _xy, wherein, x represents to launch polarization mode, and y represents to receive polarization mode; The value of xy POLARIZATION CHANNEL can be horizontal polarization mode h or vertical polarization mode v;

Concrete, according to described polarization SAR data S _xythe reference scattering matrix S generating _r, for:

$S_R=\left(\begin{array}{cc}{S}_{\mathrm{vv}}^R& S_{\mathrm{vh}}^R\\ S_{\mathrm{hv}}^R& S_{\mathrm{hh}}^R\end{array}\right),$ Wherein,

Wherein, S _xythe scatter echo signal that represents ground object target in xy POLARIZATION CHANNEL, x represents to launch polarization mode, and y represents to receive polarization mode; The value of xy POLARIZATION CHANNEL is horizontal polarization mode h or vertical polarization mode v.

Described measurement scattering matrix generation module 42 adds different isolations to crosstalk and noise described in reference to scattering matrix, generates to measure scattering matrix and generate and measure scattering matrix, specifically comprises the following steps:

Determine the polarization isolation that will the add δ that crosstalks ₁, δ ₂, δ ₃δ _n;

Determine the noise NE σ that will add ⁰ ₁, NE σ ⁰ ₂, NE σ ⁰ ₃nE σ ⁰ _m;

At S _rmiddlely add respectively a polarization isolation to crosstalk and a noise, generates n × m measurement scattering matrix M.

Concrete, the measurement scattering matrix M of described generation, for:

$M=\left(\begin{array}{cc}1& \mathrm{\δ}\\ \mathrm{\δ}& 1\end{array}\right)\left(\begin{array}{cc}{S}_{\mathrm{vv}}^R& S_{\mathrm{vh}}^R\\ S_{\mathrm{hv}}^R& S_{\mathrm{hh}}^R\end{array}\right)\left(\begin{array}{cc}1& \mathrm{\δ}\\ \mathrm{\δ}& 1\end{array}\right)+N,$

Wherein, δ represents that polarization isolation crosstalks; N is noise gain matrix.

Concrete, described polarization isolation index C calculates by following formula:

C＝-20×log10(δ)，

Wherein, δ is that polarization isolation is crosstalked.

Described polarization isolation index determination module 43 is determined the polarization isolation index in spaceborne multipolarization SAR system under different application demand according to described with reference to scattering matrix and measurement scattering matrix, comprising:

Determine described measurement scattering matrix M and with reference to scattering matrix S _rmiddle noise NE σ ⁰to the influence degree of corresponding spaceborne multipolarization SAR system applies demand parameter;

According to NE σ ⁰to spaceborne multipolarization SAR system applies demand parameter influence degree demand, determine NE σ ⁰;

Analyze described definite NE σ ⁰under, polarization isolation index C, to corresponding spaceborne multipolarization SAR system applies demand parameter influence degree, determines the polarization isolation index C under respective application demand.

Concrete, described respective application demand refers to that polarization isolation index C, to spaceborne multipolarization SAR system applies demand parameter influence degree demand, mainly comprises: polarization isolation index C decomposes verification and measurement ratio influence degree demand to target detection of terrain classification Accuracy degree demand and/or polarization isolation index C and/or polarization isolation index C influence degree demand to quality factor etc. to H/Alpha; It should be noted that, only provide some conventional application demands here; Because the parameter relating in spaceborne multipolarization SAR system is numerous, the influence degree demand according to isolation to different system application demand index, the polarization isolation index C determining is also just different.

Concrete, can determine described measurement scattering matrix M and with reference to scattering matrix S by following steps _rmiddle noise NE σ ⁰influence degree to corresponding spaceborne multipolarization SAR system applies demand parameter:

The first step: calculate with reference to scattering matrix S _rresult under different application demand, is designated as reference value std;

Second step: calculate respectively foregoing m*n and measure scattering matrix:

$\left[\begin{array}{ccccc}{M}_{11}& M_{12}& M_{13}& ...& M_{1n}\\ M_{21}& M_{22}& M_{23}& ...& M_{2n}\\ M_{31}& M_{32}& M_{33}& ...& M_{3n}\\ ...& ...& ...& ...& ...\\ M_{m1}& M_{m2}& M_{m3}& ...& M_{\mathrm{mn}}\end{array}\right]$

In the result of each M under different application demand, be designated as measured value Y _cmn; Wherein, subscript c represents different application demands.

Wherein, the polarization isolation value of crosstalking is foregoing: δ ₁, δ ₂, δ ₃δ _n;

NE σ ⁰noise value is foregoing: NE σ ⁰ ₁, NE σ ⁰ ₂, NE σ ⁰ ₃nE σ ⁰ _m;

The 3rd step: for every kind of application demand, calculate respectively different noise NE σ in the time that δ is different fixed value ⁰corresponding Y _cmn-std, the result obtaining is noise NE σ under certain δ fixed value ⁰to the influence degree of corresponding spaceborne multipolarization SAR system applies demand parameter, in actual applications, the result obtaining can be depicted as to curve map as shown in Figure 2, thereby data are analyzed more intuitively.

The 4th step: according to NE σ ⁰to spaceborne multipolarization SAR system applies demand parameter influence degree, determine the NE σ under respective application demand ⁰.

Further, as the NE σ under respective application demand ⁰after determining, as long as to described definite NE σ ⁰lower polarization isolation C analyzes the influence degree of corresponding spaceborne multipolarization SAR system applies demand parameter, just can determine the polarization isolation index C under respective application demand.

The above, be only preferred embodiment of the present invention, is not intended to limit protection scope of the present invention.

Claims (16)

1. a polarization isolation Index, is characterized in that, described method comprises:

According in airborne multi polarized SAR SAR system with the SAR data generating reference scattering matrix of the identical wave band of spaceborne multipolarization SAR system; Add different isolations to crosstalk and noise described in reference to scattering matrix, generate and measure scattering matrix; Determine the polarization isolation index in spaceborne multipolarization SAR system under different application demand according to described with reference to scattering matrix and measurement scattering matrix.

2. method according to claim 1, is characterized in that, described polarization SAR data refer to the scatter echo matrix S of ground object target in xy POLARIZATION CHANNEL _xy; Wherein, x represents to launch polarization mode, and y represents to receive polarization mode, and the value of xy POLARIZATION CHANNEL is horizontal polarization mode h or vertical polarization mode v.

3. method according to claim 2, is characterized in that, the reference scattering matrix S of described generation _r, for:

$S_R=\left(\begin{array}{cc}{S}_{\mathrm{vv}}^R& S_{\mathrm{vh}}^R\\ S_{\mathrm{hv}}^R& S_{\mathrm{hh}}^R\end{array}\right),$

Wherein, S _xythe scatter echo signal that represents ground object target in xy POLARIZATION CHANNEL, x represents to launch polarization mode, and y represents to receive polarization mode; The value of xy POLARIZATION CHANNEL is horizontal polarization mode h or vertical polarization mode v.

4. method according to claim 1, is characterized in that, scattering matrix is measured in described generation, comprising:

Determine the polarization isolation that will the add δ that crosstalks ₁, δ ₂, δ ₃δ _n;

Determine the noise NE σ that will add ⁰ ₁, NE σ ⁰ ₂, NE σ ⁰ ₃nE σ ⁰ _m;

At S _rmiddlely add respectively a polarization isolation to crosstalk and a noise, generates n × m measurement scattering matrix M.

5. method according to claim 1, is characterized in that, described measurement scattering matrix M is:

$M=\left(\begin{array}{cc}1& \mathrm{\δ}\\ \mathrm{\δ}& 1\end{array}\right)\left(\begin{array}{cc}{S}_{\mathrm{vv}}^R& S_{\mathrm{vh}}^R\\ S_{\mathrm{hv}}^R& S_{\mathrm{hh}}^R\end{array}\right)\left(\begin{array}{cc}1& \mathrm{\δ}\\ \mathrm{\δ}& 1\end{array}\right)+N,$

Wherein, δ represents that polarization isolation crosstalks; N is noise gain matrix; S _xythe scatter echo signal that represents ground object target in xy POLARIZATION CHANNEL, x represents to launch polarization mode, and y represents to receive polarization mode; The value of xy POLARIZATION CHANNEL is horizontal polarization mode h or vertical polarization mode v.

6. method according to claim 1, is characterized in that, the crosstalk pass of δ of described polarization isolation index C and polarization isolation is:

C＝-20×log10(δ)。

7. according to the wherein method described in any one of claim 1 to 6, it is characterized in that, described according to described measurement scattering matrix M with reference to scattering matrix S _rdetermine the polarization isolation index in spaceborne multipolarization SAR system under respective application demand, comprising:

Determine described measurement scattering matrix M and with reference to scattering matrix S _rmiddle noise NE σ ⁰to corresponding spaceborne multipolarization SAR system applies demand parameter influence degree;

According to NE σ ⁰to the influence degree demand of spaceborne multipolarization SAR system applies demand parameter, determine NE σ ⁰;

Analyze described definite NE σ ⁰under, the influence degree of polarization isolation index C to corresponding spaceborne multipolarization SAR system applies demand parameter, determines the polarization isolation index C under respective application demand.

8. method according to claim 7, it is characterized in that, described respective application demand, comprising: polarization isolation index C decomposes terrain classification Accuracy degree demand and/or verification and measurement ratio influence degree demand and/or the polarization isolation index C influence degree demand to quality factor of polarization isolation index C to target detection to H/Alpha.

9. a polarization isolation index determining device, is characterized in that, described device comprises: with reference to scattering matrix generation module, measurement scattering matrix generation module and polarization isolation index determination module; Wherein,

Described with reference to scattering matrix generation module, for the SAR data generating reference scattering matrix with the identical wave band of spaceborne multipolarization SAR system according to airborne synthetic aperture radar SAR system;

Described measurement scattering matrix generation module, for adding different isolations to crosstalk and noise described with reference to scattering matrix, generates and measures scattering matrix;

Described polarization isolation index determination module, for according to described with reference to scattering matrix with measure scattering matrix and determine the polarization isolation index of spaceborne multipolarization SAR system under different application demand.

10. device according to claim 9, is characterized in that, described polarization SAR data refer to the scatter echo matrix S of ground object target in xy POLARIZATION CHANNEL _xy; Wherein, x represents to launch polarization mode, and y represents to receive polarization mode, and the value of xy POLARIZATION CHANNEL is horizontal polarization mode h or vertical polarization mode v.

11. devices according to claim 10, is characterized in that, the reference scattering matrix S of described generation _r, for:

$S_R=\left(\begin{array}{cc}{S}_{\mathrm{vv}}^R& S_{\mathrm{vh}}^R\\ S_{\mathrm{hv}}^R& S_{\mathrm{hh}}^R\end{array}\right),$

Wherein, S _xythe scatter echo signal that represents ground object target in xy POLARIZATION CHANNEL, x represents to launch polarization mode, and y represents to receive polarization mode; The value of xy POLARIZATION CHANNEL is horizontal polarization mode h or vertical polarization mode v.

12. devices according to claim 9, is characterized in that, described measurement scattering matrix generation module adds different isolations to crosstalk and noise described in reference to scattering matrix, generate to measure scattering matrix and generate and measure scattering matrix, comprising:

Determine the polarization isolation that will the add δ that crosstalks ₁, δ ₂, δ ₃δ _n;

Determine the noise NE σ that will add ⁰ ₁, NE σ ⁰ ₂, NE σ ⁰ ₃nE σ ⁰ _m;

At S _rmiddlely add respectively a polarization isolation to crosstalk and a noise, generates n × m measurement scattering matrix M.

13. devices according to claim 9, is characterized in that, the measurement scattering matrix M of described generation, for:

$M=\left(\begin{array}{cc}1& \mathrm{\δ}\\ \mathrm{\δ}& 1\end{array}\right)\left(\begin{array}{cc}{S}_{\mathrm{vv}}^R& S_{\mathrm{vh}}^R\\ S_{\mathrm{hv}}^R& S_{\mathrm{hh}}^R\end{array}\right)\left(\begin{array}{cc}1& \mathrm{\δ}\\ \mathrm{\δ}& 1\end{array}\right)+N,$

Wherein, δ represents that polarization isolation crosstalks; N is noise gain matrix; S _xythe scatter echo signal that represents ground object target in xy POLARIZATION CHANNEL, x represents to launch polarization mode, and y represents to receive polarization mode; The value of xy POLARIZATION CHANNEL is horizontal polarization mode h or vertical polarization mode v.

14. devices according to claim 9, is characterized in that, the crosstalk pass of δ of described polarization isolation index C and polarization isolation is:

C＝-20×log10(δ)。

15. according to the wherein device described in any one of claim 9 to 14, it is characterized in that, described polarization isolation index determination module is determined the polarization isolation index in spaceborne multipolarization SAR system under different application demand according to described with reference to scattering matrix and measurement scattering matrix, comprising:

Determine described measurement scattering matrix M and with reference to scattering matrix S _rmiddle noise NE σ ⁰to the influence degree of corresponding spaceborne multipolarization SAR system applies demand parameter;

According to NE σ ⁰to the influence degree demand of spaceborne multipolarization SAR system applies demand parameter, determine NE σ ⁰;

Analyze described definite NE σ ⁰under, polarization isolation index C, to corresponding spaceborne multipolarization SAR system applies demand parameter influence degree, determines the polarization isolation index C index under respective application demand.

16. devices according to claim 15, it is characterized in that, described respective application demand, comprising: polarization isolation index C decomposes terrain classification Accuracy degree demand and/or verification and measurement ratio influence degree demand and/or the polarization isolation index C influence degree demand to quality factor of polarization isolation index C to target detection to H/Alpha.