Ukwahlulahlula kwe-SARichaza indlela intsimi ye-electromagnetic edluliselwa kwaye ifunyenwe yinkqubo yeradar yokuvula eyenziweyo. Ngenxa yokuba iindawo ezahlukeneyo kunye nezakhiwo zisasaza amasimi athe tye nathe nkqo ngokwahlukileyo, i-polarization yenye yezona zinto ziluncedo kakhulu ekutolikeni imifanekiso ye-SAR.
Esi sikhokelo sichaza iindlela ezine ze-linear polarization - i-HH, i-HV, i-VH kunye ne-VV - kunye neendlela ezintathu ezisetyenziswa rhoqo zokufumana: i-single polarization, i-dual polarization kunye ne-full (quad) polarization. Sikwachaza indlela iinjineli ezikhetha ngayo imo yokuqonda kude, uvavanyo lwe-radar kunye novavanyo lwe-antenna-system.
Yintoni i-SAR Polarization?
Uninzi lweenkqubo ze-SAR ezisebenzisa i-spaceborne zisebenzisa i-horizontal (H) kunye ne-vertical (V) linear polarization. Ikhowudi yetshaneli enoonobumba ababini ichaza i-transmitted polarization kuqala kwaye i-received polarization yesibini. Umzekelo, i-HH ithetha i-horizontal transmit kunye ne-horizontal receive, ngelixa i-HV ithetha i-horizontal transmit kunye ne-vertical receive.
I-Polarization ibalulekile kuba ithagethi inokugcina i-incident polarization, iyijikelezise okanye i-depolarize inxalenye ye-return. Uburhabaxa bomphezulu, i-geometry, iipropati ze-dielectric, ubude be-wavelength, i-incidence angle kunye nesakhiwo sangaphakathi zonke zichaphazela i-backscatter elinganisiweyo. I-Polarization ke ngoko kufuneka itolikwe kunye ne-frequency band, i-viewing geometry kunye nedatha yomfanekiso elinganisiweyo.
Zithetha ukuthini ii-HH, HV, VH kunye ne-VV?
| Itshaneli | Thumela | Yamkela | Ulwahlulo |
|---|---|---|---|
| HH | Ithe tyaba | Ithe tyaba | I-co-polarized |
| HV | Ithe tyaba | Ithe nkqo | I-cross-polarized |
| VH | Ithe nkqo | Ithe tyaba | I-cross-polarized |
| VV | Ithe nkqo | Ithe nkqo | I-co-polarized |
I-HH kunye ne-VV ziitshaneli ezi-co-polarized kuba ii-transmit kunye ne-receive polarizations ziyafana. I-HV kunye ne-VH ziitshaneli ezi-cross-polarized kuba i-receive polarization ihambelana ne-transmitted polarization. Kwinkqubo ye-calibrated reciprocal monostatic, iimpendulo ze-HV kunye ne-VH zihlala zifana, kodwa zombini iitshaneli zigcinwa kwiimilinganiselo ze-polarimetric ezipheleleyo.
Iindlela ezintathu eziphambili ze-SAR Polarization
1. Ukwahlulahlula okukodwa
Ukufunyanwa kwe-single-polarisation kurekhoda itshaneli enye, edla ngokuba yi-HH okanye i-VV. Inika ivolumu yedatha ephantsi kunye nokucutshungulwa okulula xa itshaneli enye eqinisekisiweyo yanele. Umda kukuba itshaneli enye inika ulwazi oluncinci malunga neendlela zokusasazeka kunye nesakhiwo sethagethi.
2. Ukwahlulahlula kabini
Ukufunyanwa kwe-dual-polarization kurekhoda iziteshi ezimbini. Iindidi eziqhelekileyo ziquka i-HH+HV kunye ne-VV+VH, apho i-radar idlulisela i-polarization enye kwaye ifumana zombini imbuyekezo ye-co- kunye ne-cross-polarized. Ezinye iinkqubo zikwaxhasa isibini se-co-pol njenge-HH+VV. Idatha ye-dual-pol yongeza ucalucalulo oluluncedo ngelixa igcina i-data-rate kunye neemfuno zokucubungula zilawuleka ngakumbi kune-polarimetry epheleleyo. I-ESA ithi i-Sentinel-1 ixhasa i-VV+VH okanye i-HH+HV kwizicwangciso zayo ze-dual-polarization.
3. Ukuqhekeka okuGqibeleleyo okanye okune-quad
I-SAR epheleleyo ye-polarimetric irekhoda i-HH, i-HV, i-VH kunye ne-VV njengeetshaneli ezintsonkothileyo. I-radar ye-quad-pol yakudala ithumela i-H kunye ne-V ngokulandelelana kwaye ifumana zombini i-H kunye ne-V returns, igcina ulwazi lwe-amplitude kunye ne-relative phase. Oku kuxhasa uhlalutyo lwe-scattering-matrix kunye nokuqhekeka okuneenkcukacha kwethagethi, ukuhlelwa kunye nokuchazwa kweempawu.
Utshintsho lubangelwa bubunzima obukhulu benkqubo, imfuno yokulinganisa, umthamo wedatha kunye nomzamo wokucubungula. Ngokuxhomekeke kwisenzi, ukusebenza kwe-full-pol kunokubandakanya i-swath encinci okanye imida eyahlukileyo yokufumana. I-compact polarization lolunye uyilo lwe-SAR olusebenzayo, kodwa lwahlukile kwiindlela zendabuko ze-single-, dual- kunye ne-quad-pol linear ezixutyushwa apha.
I-Co-Polarization vs. I-Cross-Polarization
Iitshaneli ezidibanisa i-polarized zihlala zigcina ukubuya okunamandla okuvela kwiindawo kunye nezakhiwo ezigcina i-polarized edluliselweyo. Ukubuya kwe-cross-polarized kubonisa ukuba inkqubo yokusasazeka itshintshe inxalenye yemeko ye-polarized ngokusebenzisa i-volume scattering, i-multiple reflections, i-complex geometry okanye isakhiwo se-anisotropic.
- Amanzi azolileyo kunye neendawo ezithambileyo:zidla ngokubonakala zimnyama xa uninzi lwamandla lubonakala kude ne-radar; uburhabaxa, umoya kunye ne-engile yokwenzeka kwezinto zinokunyusa ukusasazwa kwemozulu.
- Imifuno:Amasebe, iziqu kunye namagqabi adala ukusasazeka komthamo, ngoko ke imijelo enqamlezileyo inokongeza ulwazi oluxabisekileyo lwesakhiwo.
- Iindawo zasezidolophini:Izakhiwo kunye nomphezulu womhlaba zinokuvelisa ukubuya okunamandla kwe-co-pol kunye nokusasazeka kwe-double-bounce, kuxhomekeke kwindlela ojongwa ngayo kunye nejometri yomfanekiso.
- Umhlaba, ikhephu kunye nomkhenkce:ukufuma, uburhabaxa, ubunzulu, ubude bomda kunye nolwakhiwo lwangaphakathi zonke ezi zinto zichaphazela impendulo ye-polarization.
Le yimigaqo yokutolika kunokuba ibe yimithetho eqhelekileyo. Itshaneli akufuneki ikhethwe ngokuzimeleyo ngokwebhendi yeradar, i-incidence angle, isisombululo, ixesha kunye nomgangatho wokulinganisa.
Indlela yokukhetha iModi ye-SAR Polarization
| Imfuneko | Indawo yokuqala esebenzayo |
|---|---|
| Ukubeka esweni indawo ebanzi okanye umthamo wedatha olinganiselweyo | I-single-pol xa itshaneli eqinisekisiweyo ihlangabezana nenjongo yokufumanisa |
| Ukucalucalulwa kwemifuno, ezolimo okanye ukugqunywa komhlaba | Idatha edibeneyo ye-dual-pol kunye ne-cross-polarized yolwazi olongezelelweyo lokusasazeka |
| Imephu yomkhenkce wolwandle, ulwandle okanye izikhukula | Khetha iindlela ezisekelwe kwi-HH okanye kwi-VV ngokwebhendi, i-engile yeziganeko kunye nendlela eqinisekisiweyo |
| Uhlu oluphambili okanye ukubola okusasazekayo | I-quad-pol epheleleyo xa kufuneka ulwazi oluneendlela ezine ezilinganiswe ngesigaba |
Eyona ndlela ilungileyo ihambelana nesicelo. Iinjineli kufuneka zithelekise umxholo wolwazi kunye nokugubungela, isisombululo, umlinganiselo wesignali-kwingxolo, ukujika, ixesha lokujonga kwakhona, izixhobo zokucubungula kunye nokukwazi ukulinganisa.
Izinto eziqwalaselwa yi-Antenna kunye ne-RF kwi-Polarimetric Radar
Ukulinganiswa kwe-polarimetric okuthembekileyo kuxhomekeke kokungaphezulu kune-algorithm yokucubungula. I-antenna kunye ne-RF chain kufuneka zigcine ukusebenza okuzinzileyo kuzo zombini iitshaneli ze-polarisation. Iiparameter ezibalulekileyo ziquka:
- i-frequency yokusebenza kunye ne-bandwidth ekhawulezileyo;
- ibhalansi yenzuzo kunye nepatheni yemitha phakathi kwee-ports ze-H kunye ne-V;
- ukwahlulwa kwabantu abavela kwamanye amazwe ukuya kwamanye amazwe kunye nocalucalulo oluvela kwamanye amazwe;
- ubukhulu kunye nozinzo lwesigaba;
- I-VSWR, ujongano lwekhonkco kunye nokulinganiswa kwentambo;
- ulungelelwaniso lwe-antenna, i-geometry yokufakela kunye ne-calibration reference plane.
Izixhobo ze-RF MISOii-antennas zeempondo eziphindwe kabini, ii-eriyali zeempondo ezibanzi eziphindwe kabinikunye nezinye izisombululo ze-antenna ze-RF zomsebenzi we-radar, ukulinganisa kunye nomsebenzi wokudibanisa inkqubo. Ukukhethwa kwemodeli kufuneka kusekelwe rhoqo kwiphepha ledatha langoku kunye neemfuno zovavanyo olupheleleyo.
Imibuzo ebuzwa qho
Ngowuphi unobumba oza kuqala kwikhowudi ye-SAR polarization?
Unobumba wokuqala uchaza i-transmitted polarization kwaye owesibini uchaza i-received polarization. I-HV ithetha i-horizontal transmit kunye ne-vertical receive.
Yintoni umahluko phakathi kwe-dual-pol kunye ne-quad-pol SAR?
I-Dual-pol irekhoda iziteshi ezimbini, ezidla ngokuba yi-HH+HV okanye i-VV+VH. I-Quad-pol irekhoda i-HH, i-HV, i-VH kunye ne-VV kwaye igcina ubudlelwane obufunekayo kuhlalutyo olupheleleyo lwe-polarimetric.
Ngaba i-SAR polarization enye isoloko ingcono?
Hayi. Eyona ndlela iluncedo kakhulu ixhomekeke kwithagethi, ubude be-radar, i-incidence angle, isisombululo, iimeko zokusingqongileyo kunye nenjongo yokucubungula.
Kutheni iziteshi ze-cross-pol ziluncedo?
I-HV okanye i-VH ingatyhila ukusasazeka okutshintsha ukuqhekeka kweziganeko, ingakumbi ukusasazeka komthamo kunye neendawo ezintsonkothileyo zesakhiwo ezifana nezityalo.
Isiphelo
I-SAR polarization ilawula indlela i-radar ekhanyisa ngayo ithagethi kunye nendlela intsimi ebuyiselweyo elinganiswa ngayo. I-HH kunye ne-VV ziitshaneli ezi-co-polarized, ngelixa i-HV kunye ne-VH zi-cross-polarized. I-Single-pol inika ukusebenza kakuhle, i-dual-pol yongeza ucalucalulo, kwaye i-full quad-pol inika iseti yedatha ye-polarimetric egqibeleleyo. Iziphumo ezichanekileyo zifuna ukuba imo yokufumana, inkqubo ye-antenna, indlela yokulinganisa kunye neemfuno zesicelo ziqwalaselwe kunye.
Ukuze ufumane ukukhethwa kwe-antenna okanye inkxaso yokulinganisa i-polarimetric RF, jonga ii-RF MISO'subuchule bokuvavanya i-antenna or Nxibelelana neqela le-RF MISO.
Iingxelo kunye nokufunda okungakumbi
Ukuze ufunde okungakumbi ngee-antenna, nceda undwendwele:
Ixesha leposi: Juni-28-2024
