Yiziphi izindlela ezintathu ezihlukene ze-polarization ze-SAR?

1. Yini i-SARi-polarization?
I-polarization: H i-polarization enezingqimba; I-V vertical polarization, okungukuthi, isiqondiso sokudlidliza senkambu ye-electromagnetic. Lapho isathelayithi idlulisela isignali phansi, indlela yokudlidliza yegagasi lomsakazo elisetshenzisiwe ingaba ngezindlela eziningi. Ezisetshenziswayo njengamanje yilezi:

I-polarization evundlile (H-horizontal): I-polarization evundlile isho ukuthi uma isathelayithi idlulisela isignali phansi, ukudlidliza kwegagasi lomsakazo wayo kuqondile. I-polarization eqondile (V-vertical): I-polarization eqondile isho ukuthi lapho isathelayithi idlulisela isignali phansi, ukudlidliza kwegagasi lomsakazo wayo kume mpo.

I-electromagnetic wave transmission ihlukaniswe ngamagagasi avundlile (H) namagagasi aqondile (V), futhi ukwamukela kuphinde kuhlukaniswe ngo-H no-V. Isistimu ye-radar esebenzisa i-H kanye no-V yomugqa we-polarization isebenzisa ipheya yezimpawu ukumela ukudluliswa nokwamukela i-polarization, ngakho-ke ingaba nalawa mashaneli alandelayo—HH, VV, HV, VH.

(1) HH - yokudlulisela okuvundlile kanye nokwamukela okuvundlile

(2) I-VV - yokudlulisela okuqondile kanye nokwamukela okuqondile

(3) HV - yokudlulisela okuvundlile kanye nokwamukela okuqondile

(4) I-VH - yokudlulisela okuqondile kanye nokwamukela okuvundlile

Ezimbili zokuqala zalezi zinhlanganisela ze-polarization zibizwa ngokuthi i-polarizations efanayo ngoba ukudlulisa nokwamukela ukuhlukaniswa kuyafana. Izinhlanganisela ezimbili zokugcina zibizwa ngokuthi i-cross polarizations ngoba ukudlulisa nokwamukela ama-polarizations kukhona orthogonal komunye nomunye.

2. Yiziphi i-polarization eyodwa, i-dual polarization, kanye ne-polarization egcwele ku-SAR?

I-polarization eyodwa ibhekisela ku-(HH) noma (VV), okusho ukuthi (ukudluliselwa okuvundlile nokwamukela okuvundlile) noma (ukudluliselwa okuqondile nokwamukela okuqondile) (uma ufunda umkhakha we-radar ye-meteorological, ngokuvamile (HH).

I-Dual polarization ibhekisela ekungezeni enye imodi ye-polarization kumodi eyodwa ye-polarization, efana (HH) yokudlulisela okuvundlile kanye nokwamukela okuvundlile + (HV) ukudluliswa okuvundlile kanye nokwamukela okuqondile.

Ubuchwepheshe obugcwele be-polarization bunzima kakhulu, obudinga ukudluliswa kanyekanye kwe-H no-V, okungukuthi, izindlela ezine ze-polarization ze-(HH) (HV) (VV) (VH) zikhona ngesikhathi esisodwa.

Amasistimu e-radar angaba namazinga ahlukene we-polarization complexity:

(1) I-polarization eyodwa: HH; I-VV; HV; VH

(2)I-polarization ekabili: HH+HV; I-VV+VH; HH+VV

(3) Ukuhlukaniswa okune: HH+VV+HV+VH

I-Orthogonal polarization (okungukuthi i-polarization egcwele) ama-radar asebenzisa lezi zinhlaka ezine futhi alinganise umehluko wesigaba phakathi kwamashaneli kanye nobukhulu. Amanye ama-radar e-dual-polarization nawo akala umehluko wesigaba phakathi kwamashaneli, njengoba lesi sigaba sidlala indima ebalulekile ekukhishweni kolwazi lwe-polarization.

Isithombe sesathelayithi ye-radar Ngokwe-polarization, izinto ezibonwayo ezihlukene zisakaza amaza ahlukene e-polarization kumagagasi ezigameko ezihlukene. Ngakho-ke, inzwa yerimothi yesikhala ingasebenzisa amabhendi amaningi ukuze kwandiswe okuqukethwe kolwazi, noma isebenzise ukuhlukaniswa okuhlukile ukuze kuthuthukiswe futhi kuthuthukiswe ukunemba kokuhlonza okuqondiwe.

3. Ungakhetha kanjani imodi ye-polarization yesathelayithi ye-radar ye-SAR?

Okuhlangenwe nakho kubonisa ukuthi:

Kuzinhlelo zokusebenza zasolwandle, i-HH polarization ye-L band izwela kakhulu, kuyilapho i-VV polarization ye-C band ingcono;

Ngotshani obuhlakazekile kancane kanye nemigwaqo, i-polarization evundlile yenza izinto zibe nomehluko omkhulu, ngakho-ke i-SAR yasemkhathini esetshenziselwa ukudweba imephu yendawo isebenzisa i-polarization evundlile; endaweni enobunzima obukhulu kunobude begagasi, alukho ushintsho olusobala ku-HH noma ku-VV.

Amandla e-echo ento efanayo ngaphansi kwe-polarizations ehlukene ahlukile, futhi ithoni yesithombe nayo ihlukile, okwandisa ulwazi lokuhlonza into eqondiwe. Ukuqhathanisa ulwazi lwe-polarization efanayo (HH, VV) kanye ne-cross-polarization (HV, VH) kungakhuphula kakhulu ulwazi lwesithombe se-radar, futhi umehluko wolwazi phakathi kwe-polarization echoes yezitshalo nezinye izinto ezahlukene uzwela kakhulu kunomehluko phakathi amabhande ahlukene.
Ngakho-ke, ekusetshenzisweni okungokoqobo, imodi efanele ye-polarization ingakhethwa ngokuvumelana nezidingo ezahlukene, futhi ukusetshenziswa okuphelele kwezindlela eziningi ze-polarization kulungele ukuthuthukisa ukunemba kokuhlukaniswa kwezinto.