Menene nau'ikan polarization daban-daban guda uku na SAR?

1. Menene SARpolarization?
Polarization: H a kwance polarization; V a tsaye polarization, wato, alkiblar girgizar filin lantarki. Lokacin da tauraron dan adam ya aika da sigina zuwa ƙasa, yanayin girgizar igiyar rediyon da ake amfani da ita na iya kasancewa ta hanyoyi da yawa. Wadanda ake amfani da su a halin yanzu sune:

Horizontal polarization (H-horizontal): Tsabtace polarization yana nufin cewa lokacin da tauraron dan adam ya aika da sigina zuwa ƙasa, yanayin girgizar igiyar rediyonsa tana kwance. Vertical polarization (V-vertical): Tsayayyen polarization yana nufin cewa lokacin da tauraron dan adam ya aika da sigina zuwa ƙasa, yanayin girgizar igiyoyin rediyonsa yana tsaye.

Ana raba watsa wutar lantarki zuwa igiyoyin kwance (H) da kuma igiyoyin ruwa na tsaye (V), sannan liyafar kuma ta kasu zuwa H da V. Tsarin radar da ke amfani da polarization na H da V yana amfani da alamomi guda biyu don wakiltar watsawa da liyafar polarization. don haka yana iya samun tashoshi masu zuwa-HH, VV, HV, VH.

(1) HH - don watsawa a kwance da liyafar kwance

(2) VV - don watsawa a tsaye da liyafar tsaye

(3) HV - don watsawa a kwance da liyafar tsaye

(4) VH - don watsawa a tsaye da liyafar kwance

Biyu na farko na waɗannan haɗin gwiwar polarization ana kiran su da irin wannan polarizations saboda watsawa da karɓar polarizations iri ɗaya ne. Haɗuwa biyu na ƙarshe ana kiran su giciye polarizations saboda watsawa da karɓar polarizations na ƙayyadaddun tsari ne ga juna.

2. Menene polarization guda ɗaya, polarization biyu, da cikakken polarization a cikin SAR?

Single polarization yana nufin (HH) ko (VV), wanda ke nufin ( watsawa a kwance da liyafar kwance ) ko ( watsawa a tsaye da liyafar tsaye ) (idan kuna nazarin filin radar meteorological, gabaɗaya (HH) ne).

Dual polarization yana nufin ƙara wani yanayin polarization zuwa yanayin polarization ɗaya, kamar (HH) watsawa a kwance da liyafar kwance + (HV) watsawa a kwance da liyafar tsaye.

Cikakken fasahar polarization ita ce mafi wahala, tana buƙatar watsawar H da V a lokaci guda, wato, hanyoyin polarization huɗu na (HH) (HV) (VV) (VH) suna wanzuwa a lokaci guda.

Tsarin radar na iya samun matakai daban-daban na rikitarwa na polarization:

(1) Guda ɗaya: HH; VV; HV; VH

(2)Dual polarization: HH+HV; VV+VH; HH+VV

(3) Matsaloli huɗu: HH+VV+HV+VH

Ƙaƙwalwar ƙira (watau cikakken polarization) radars suna amfani da waɗannan polarizations guda huɗu kuma suna auna bambancin lokaci tsakanin tashoshi da girman girman. Wasu radars biyu-polarization kuma suna auna bambance-bambancen lokaci tsakanin tashoshi, saboda wannan lokaci yana taka muhimmiyar rawa wajen fitar da bayanan polarization.

Hoton tauraron dan adam na Radar Dangane da polarization, abubuwa daban-daban da aka gani suna watsar da raƙuman ruwa na polarization daban-daban don raƙuman polarization daban-daban. Don haka, hangen nesa na sararin samaniya na iya amfani da makada da yawa don ƙara abun ciki na bayanai, ko amfani da polarizations daban-daban don haɓakawa da haɓaka daidaiton gano manufa.

3. Yadda za a zabi yanayin polarization na SAR radar tauraron dan adam?

Kwarewa ta nuna cewa:

Don aikace-aikacen marine, HH polarization na L band ya fi hankali, yayin da polarization na VV na band C ya fi kyau;

Don ƙananan ciyayi da hanyoyi, a kwance polarization yana sa abubuwa su sami bambance-bambance masu girma, don haka SAR sararin samaniya da ake amfani da shi don taswirar ƙasa yana amfani da polarization a kwance; don ƙasar da ke da roughness mafi girma fiye da tsayin raƙuman ruwa, babu wani canji a fili a HH ko VV.

Ƙarfin echo na abu ɗaya a ƙarƙashin maɓalli daban-daban ya bambanta, kuma sautin hoton kuma ya bambanta, wanda ke ƙara bayani don gano abin da ake nufi. Kwatanta bayanan polarization iri ɗaya (HH, VV) da giciye-polarization (HV, VH) na iya haɓaka bayanan hoto na radar sosai, kuma bambancin bayanin da ke tsakanin ciyayi da sauran abubuwa daban-daban yana da hankali fiye da bambanci tsakanin. daban-daban makada.
Sabili da haka, a cikin aikace-aikacen aiki, ana iya zaɓar yanayin polarization da ya dace bisa ga buƙatu daban-daban, kuma cikakken amfani da yanayin polarization da yawa yana da kyau don inganta daidaiton rarrabuwar abubuwa.