SAR polarizationpiav qhia txog kev taw qhia ntawm lub zog hluav taws xob uas xa thiab tau txais los ntawm lub tshuab radar aperture. Vim tias cov nto thiab cov qauv sib txawv faib cov teb kab rov tav thiab ntsug sib txawv, polarization yog ib qho ntawm cov hloov pauv muaj txiaj ntsig zoo tshaj plaws rau kev txhais cov duab SAR.
Phau ntawv qhia no piav qhia txog plaub txoj kab sib txuas linear polarization - HH, HV, VH thiab VV - thiab peb hom kev siv feem ntau: ib qho polarization, ob qho polarization thiab puv (quad) polarization. Nws kuj piav qhia txog yuav ua li cas cov engineers xaiv hom rau kev tshawb nrhiav chaw deb, kev sim radar thiab kev ntsuam xyuas lub antenna-system.
SAR Polarization yog dab tsi?
Feem ntau cov kab ke SAR uas ya mus rau saum ntuj siv cov kab rov tav (H) thiab ntsug (V) linear polarization. Ib daim code channel ob tsab ntawv qhia txog qhov polarization uas xa tawm ua ntej thiab qhov polarization uas tau txais ua ntej. Piv txwv li, HH txhais tau tias xa kab rov tav thiab txais kab rov tav, thaum HV txhais tau tias xa kab rov tav thiab txais kab rov tav.
Kev sib cais polarization tseem ceeb vim tias lub hom phiaj tuaj yeem khaws cia qhov tshwm sim polarization, tig nws lossis depolarize ib feem ntawm qhov rov qab. Qhov roughness ntawm qhov chaw, geometry, dielectric properties, wavelength, incidence angle thiab sab hauv cov qauv txhua yam cuam tshuam rau qhov ntsuas backscatter. Yog li ntawd, kev sib cais polarization yuav tsum tau txhais ua ke nrog frequency band, viewing geometry thiab calibrated image data.
HH, HV, VH thiab VV txhais li cas?
| Channel | Xa mus | Txais | Kev faib tawm |
|---|---|---|---|
| HH | Kab rov tav | Kab rov tav | Co-polarized |
| HV | Kab rov tav | Ntsug | Cross-polarized |
| VH | Ntsug | Kab rov tav | Cross-polarized |
| VV | Ntsug | Ntsug | Co-polarized |
HH thiab VV yog cov channel co-polarized vim tias qhov kev xa tawm thiab txais polarizations yog tib yam. HV thiab VH yog cov channel hla-polarized vim tias qhov kev txais polarization yog orthogonal rau qhov kev xa tawm polarization. Hauv lub kaw lus calibrated reciprocal monostatic, HV thiab VH cov lus teb feem ntau zoo sib xws, tab sis ob qho channel tau khaws cia rau hauv kev ntsuas polarimetric tag nrho.
Peb Hom Kev Sib Cais SAR Tseem Ceeb
1. Ib qho Polarization
Ib qho kev tau txais ib qho polarization kaw ib txoj kab ke, feem ntau yog HH lossis VV. Nws muab cov ntaub ntawv tsawg dua thiab ua tiav yooj yim dua thaum ib txoj kab ke uas tau lees paub txaus. Qhov txwv yog tias ib txoj kab ke muab cov ntaub ntawv tsawg dua txog cov txheej txheem scattering thiab cov qauv ntawm lub hom phiaj.
2. Ob Chav Polarization
Ib qho kev tau txais dual-polarization kaw ob txoj kab ke. Kev sib xyaw ua ke suav nrog HH + HV thiab VV + VH, qhov twg lub radar xa ib qho polarization thiab tau txais ob qho tib si co- thiab cross-polarized rov qab. Qee lub tshuab kuj txhawb nqa ib khub co-pol xws li HH + VV. Cov ntaub ntawv dual-pol ntxiv kev faib tawm muaj txiaj ntsig thaum khaws cov ntaub ntawv-nqi thiab cov kev xav tau ua tiav ntau dua li polarimetry tag nrho. ESA hais tias Sentinel-1 txhawb nqa VV + VH lossis HH + HV hauv nws cov phiaj xwm dual-polarization.
3. Tag Nrho Los Yog Quad Polarization
SAR polarimetric tag nrho sau HH, HV, VH thiab VV ua cov channel nyuaj. Lub radar quad-pol classical xa H thiab V ua ntu zus thiab tau txais ob qho tib si H thiab V rov qab, khaws cov ntaub ntawv amplitude thiab cov ntaub ntawv theem sib piv. Qhov no txhawb nqa kev tshuaj xyuas scattering-matrix thiab kev rhuav tshem cov hom phiaj kom ntxaws, kev faib tawm thiab kev piav qhia.
Qhov kev pauv pauv yog qhov nyuaj ntawm lub kaw lus, qhov xav tau calibration, qhov ntim ntawm cov ntaub ntawv thiab kev siv zog ua tiav. Nyob ntawm lub sensor, kev ua haujlwm puv-pol kuj tseem yuav cuam tshuam nrog qhov nqaim dua lossis cov kev txwv ntawm kev tau txais sib txawv. Compact polarization yog lwm lub qauv SAR uas siv tau, tab sis nws txawv ntawm cov qauv ib leeg, ob- thiab plaub-pol linear uas tau tham txog ntawm no.
Co-Polarization vs. Cross-Polarization
Cov channel co-polarized feem ntau khaws cov khoom rov qab los ntawm cov nto thiab cov qauv uas tswj cov polarization xa mus. Cov khoom rov qab hla-polarized qhia tias cov txheej txheem scattering hloov pauv ib feem ntawm lub xeev polarization los ntawm kev scattering ntim, ntau qhov kev cuam tshuam, geometry nyuaj lossis cov qauv anisotropic.
- Dej ntsiag to thiab cov nto du:feem ntau tshwm sim tsaus ntuj thaum feem ntau lub zog raug cuam tshuam tawm ntawm lub radar; qhov ntxhib, cua thiab lub kaum sab xis tuaj yeem ua rau backscatter nce ntxiv.
- Cov nroj tsuag:cov ceg, cov cev ntoo thiab cov nplooj ua rau muaj qhov sib txawv ntawm qhov ntim, yog li cov channel hla-pol tuaj yeem ntxiv cov ntaub ntawv tseem ceeb ntawm cov qauv.
- Cov cheeb tsam hauv nroog:cov tsev thiab cov av hauv av tuaj yeem tsim cov co-pol rov qab muaj zog thiab ob chav bounce scattering, nyob ntawm qhov kev taw qhia thiab kev kos duab geometry.
- Av, daus thiab dej khov:dej noo, qhov ntxhib, qhov tob, qhov ntev ntawm qhov ntev thiab cov qauv sab hauv txhua yam cuam tshuam rau kev teb polarization.
Cov no yog cov ntsiab cai txhais lus es tsis yog cov cai thoob ntiaj teb. Ib txoj channel yuav tsum tsis txhob raug xaiv ywj siab ntawm radar band, lub kaum sab xis, kev daws teeb meem, lub caij thiab qhov zoo ntawm kev ntsuas.
Yuav Xaiv Hom SAR Polarization Li Cas
| Qhov Yuav Tsum Tau Ua | Qhov pib ua tau zoo |
|---|---|
| Kev saib xyuas dav dav lossis cov ntaub ntawv tsawg | Ib qho kev xaiv thaum ib txoj kev channel uas tau lees paub ua tau raws li lub hom phiaj nrhiav pom |
| Kev ntxub ntxaug ntawm cov nroj tsuag, kev ua liaj ua teb lossis kev npog av | Cov ntaub ntawv dual-pol co- thiab cross-polarized rau cov ntaub ntawv scattering ntxiv |
| Daim ntawv qhia txog dej khov hauv hiav txwv, dej hiav txwv lossis dej nyab | Xaiv cov hom HH- lossis VV raws li band, lub kaum sab xis thiab txoj kev lees paub |
| Kev faib tawm qib siab lossis kev tawg ua tej daim me me | Tag nrho plaub-pol thaum xav tau cov ntaub ntawv plaub-channel uas tau teeb tsa theem |
Hom zoo tshaj plaws yog siv rau txhua daim ntawv thov. Cov kws ua vaj tse yuav tsum piv cov ntsiab lus ntawm cov ntaub ntawv nrog rau kev npog, kev daws teeb meem, qhov sib piv ntawm lub teeb liab thiab lub suab nrov, qhov dav, lub sijhawm rov mus saib dua, cov peev txheej ua haujlwm thiab lub peev xwm calibration.
Kev Xav Txog Antenna thiab RF rau Polarimetric Radar
Kev ntsuas polarimetric txhim khu kev qha nyob ntawm ntau dua li cov txheej txheem ua tiav. Lub kav hlau txais xov thiab RF saw hlau yuav tsum tswj kev ua haujlwm ruaj khov hauv ob txoj kev sib hloov polarization. Cov kev ntsuas tseem ceeb suav nrog:
- zaus ua haujlwm thiab bandwidth tam sim ntawd;
- qhov nce thiab qhov sib npaug ntawm cov qauv hluav taws xob ntawm H thiab V chaw nres nkoj;
- kev sib cais ntawm chaw nres nkoj mus rau chaw nres nkoj thiab kev sib cais hla polar;
- qhov loj thiab qhov ruaj khov ntawm theem;
- VSWR, qhov sib txuas interface thiab kev kho qhov cable;
- kev sib dhos ntawm lub antenna, kev teeb tsa geometry thiab kev ntsuas qhov ntsuas.
Cov khoom siv RF MISOob lub polarized horn antennas, broadband dual-polarized horn antennasthiab lwm yam kev daws teeb meem RF antenna rau radar, kev ntsuas thiab kev sib koom ua ke ntawm lub kaw lus. Kev xaiv qauv yuav tsum ib txwm ua raws li cov ntaub ntawv tam sim no thiab qhov yuav tsum tau ua tiav ntawm kev xeem.
Cov Lus Nug Feem Ntau
Tsab ntawv twg los ua ntej hauv SAR polarization code?
Tsab ntawv thawj zaug qhia txog qhov polarization xa mus thiab tsab ntawv thib ob qhia txog qhov polarization tau txais. HV txhais tau tias xa kab rov tav thiab txais ntsug.
Qhov txawv ntawm dual-pol thiab quad-pol SAR yog dab tsi?
Dual-pol kaw ob txoj kab, feem ntau yog HH+HV lossis VV+VH. Quad-pol kaw HH, HV, VH thiab VV thiab khaws cov kev sib raug zoo uas xav tau rau kev tshuaj xyuas polarimetric tag nrho.
Puas yog ib qho kev sib cais ntawm SAR yeej ib txwm zoo tshaj?
Tsis yog. Hom kev siv tau zoo tshaj plaws nyob ntawm lub hom phiaj, radar wavelength, incidence angle, resolution, environmental conditions thiab processing hom phiaj.
Vim li cas cov channel hla-pol thiaj muaj txiaj ntsig?
HV lossis VH tuaj yeem qhia txog kev tawg ua tej daim me me uas hloov qhov xwm txheej polarization, tshwj xeeb tshaj yog qhov ntim tawg thiab cov hom phiaj nyuaj xws li cov nroj tsuag.
Xaus lus
Kev sib hloov ntawm SAR tswj hwm seb lub radar ci ntsa iab li cas rau lub hom phiaj thiab seb qhov teb rov qab los ntsuas li cas. HH thiab VV yog cov channel sib koom ua ke, thaum HV thiab VH yog hla-polarized. Ib-pol muab kev ua haujlwm zoo, ob-pol ntxiv kev sib cais, thiab tag nrho quad-pol muab cov ntaub ntawv linear polarimetric tiav tshaj plaws. Cov txiaj ntsig tseeb yuav tsum tau xav txog hom kev tau txais, lub kaw lus antenna, txoj kev ntsuas thiab cov kev cai thov kom tau txiav txim siab ua ke.
Rau kev xaiv antenna lossis kev txhawb nqa kev ntsuas polarimetric RF, saib RF MISO'smuaj peev xwm kuaj xyuas antenna or tiv tauj pab pawg RF MISO.
Cov Lus Qhia thiab Kev Nyeem Ntxiv
Yog xav paub ntxiv txog antennas, thov mus saib:
Lub sijhawm tshaj tawm: Lub Rau Hli-28-2024
