Kugawanika kwa SARimafotokoza momwe mphamvu yamagetsi imayendera ndikulandiridwa ndi makina opangira radar. Chifukwa chakuti malo ndi mapangidwe osiyanasiyana amabalalitsa minda yopingasa ndi yoyima mosiyana, polarization ndi imodzi mwazofunikira kwambiri potanthauzira zithunzi za SAR.
Bukuli likufotokoza njira zinayi zolumikizirana - HH, HV, VH ndi VV - ndi njira zitatu zomwe zimagwiritsidwa ntchito kwambiri: kulumikizana kwa single polarization, dual polarization ndi full (quad) polarization. Limafotokozanso momwe mainjiniya amasankhira njira yolumikizira kutali, kuyesa radar ndi kuwunika kwa antenna-system.
Kodi SAR Polarization ndi Chiyani?
Makina ambiri a SAR okhala ndi malo ozungulira amagwiritsa ntchito polarization yolunjika (H) ndi yolunjika (V). Khodi ya njira yokhala ndi zilembo ziwiri imadziwika poyamba polarization yotumizidwa ndipo yachiwiri polarization yolandiridwa. Mwachitsanzo, HH imatanthauza transmit yopingasa ndi yopingasa yolandira, pomwe HV imatanthauza transmit yopingasa ndi yopingasa yolandira.
Kugawa kwa polarization ndikofunikira chifukwa cholinga chimatha kusunga kugawa kwa incident, kuchizunguliza kapena kuchotsa polarization mbali ya return. Kukhwima kwa pamwamba, geometry, dielectric properties, wavelength, incidence angle ndi internal structure zonse zimakhudza backscatter yoyesedwa. Chifukwa chake, kugawa kwa polarization kuyenera kutanthauziridwa limodzi ndi frequency band, viewing geometry ndi calibrated image data.
Kodi HH, HV, VH ndi VV Zimatanthauza Chiyani?
| Njira | Tumizani | Landirani | Kugawa |
|---|---|---|---|
| HH | Yopingasa | Yopingasa | Co-polarized |
| HV | Yopingasa | Choyimirira | Wopingasa |
| VH | Choyimirira | Yopingasa | Wopingasa |
| VV | Choyimirira | Choyimirira | Co-polarized |
HH ndi VV ndi njira zolumikizirana chifukwa ma transmit ndi receiver polarization ndi ofanana. HV ndi VH ndi njira zolumikizirana chifukwa ma receiver polarization ndi olunjika ku ma transmit polarization. Mu calibrated reciprocal monostatic system, ma HV ndi VH response nthawi zambiri amakhala ofanana, koma njira zonse ziwiri zimasungidwa muyeso wathunthu wa polarimetric.
Njira Zitatu Zazikulu Zolumikizira SAR
1. Kugawanika Kokha
Kupeza njira imodzi yokha yolumikizirana kumalemba njira imodzi, makamaka HH kapena VV. Kumapereka kuchuluka kochepa kwa deta komanso kukonza kosavuta ngati njira imodzi yovomerezeka ili yokwanira. Cholepheretsa ndichakuti njira imodzi imapereka chidziwitso chochepa chokhudza njira zobalalitsira ndi kapangidwe ka cholinga.
2. Kugawanika Kwawiri
Kupeza ma polarization awiri kumalemba njira ziwiri. Kuphatikiza kofala kumaphatikizapo HH+HV ndi VV+VH, komwe radar imatumiza polarization imodzi ndikulandira zonse ziwiri co- ndi cross-polarized returns. Machitidwe ena amathandiziranso co-pol awiri monga HH+VV. Deta ya dual-pol imawonjezera kusiyanitsa kothandiza pamene ikusunga zofunikira pa data-rate ndi processing kukhala zosavuta kuzilamulira kuposa polarimetry yonse. ESA imati Sentinel-1 imathandizira VV+VH kapena HH+HV mu njira zake za dual-polarized.
3. Kugawanika Kwathunthu kapena Kwachinayi
SAR yonse ya polarimetric imalemba HH, HV, VH ndi VV ngati njira zovuta. Radar yakale ya quad-pol imatumiza H ndi V motsatizana ndipo imalandira zonse ziwiri H ndi V returns, kusunga amplitude ndi relative phase. Izi zimathandiza kusanthula kwa scattering-matrix ndi tsatanetsatane wa kugawa kwa chandamale, kugawa magulu ndi kufotokozera.
Kusinthaku ndi kovuta kwambiri kwa makina, kufunikira kwa calibration, kuchuluka kwa deta, ndi khama lokonza. Kutengera ndi sensa, ntchito yonse ya pol ingakhalenso ndi njira yocheperako kapena zoletsa zosiyanasiyana zopezera. Compact polarization ndi kapangidwe kena kovomerezeka ka SAR, koma ndikosiyana ndi njira zachikhalidwe za single-, dual- ndi quad-pol linear zomwe zafotokozedwa pano.
Kugwirizanitsa Polarization ndi Kugwirizanitsa Polarization
Ma channel opangidwa ndi polarized nthawi zambiri amasunga kubweza kwamphamvu kuchokera pamwamba ndi kapangidwe kake komwe kumasunga polarization yotumizidwa. Kubweza kwa polarized cross-polarized kumasonyeza kuti njira yobalalitsira inasintha gawo la mkhalidwe wa polarization kudzera mu kufalikira kwa voliyumu, kuwunikira kwamitundu yambiri, mawonekedwe ovuta kapena kapangidwe ka anisotropic.
- Madzi odekha ndi malo osalala:Nthawi zambiri zimaoneka zakuda pamene mphamvu zambiri zimaonekera kutali ndi radar; kuuma, mphepo ndi ngodya ya zochitika zimatha kuwonjezera kufalikira kwa mphepo.
- Zomera:Nthambi, thunthu ndi masamba zimapangitsa kuti nthaka ifalikire, kotero kuti njira zodutsa m'mphepete mwa nthaka zitha kuwonjezera chidziwitso chofunikira cha kapangidwe kake.
- Madera akumatauni:Nyumba ndi malo apansi zimatha kupanga ma co-pol amphamvu komanso kufalikira kwa double-bounce, kutengera momwe zinthu zilili komanso momwe zithunzi zimaonekera.
- Dothi, chipale chofewa ndi ayezi:chinyezi, kuuma, kuya, kutalika kwa mlengalenga ndi kapangidwe ka mkati zonse zimakhudza momwe polarization imayankhira.
Izi ndi mfundo zomasulira osati malamulo wamba. Njira siyenera kusankhidwa mosasamala kanthu za radar band, incidence angle, resolution, season ndi calibration quality.
Momwe Mungasankhire Njira Yolumikizira SAR
| Chofunikira | Poyambira kothandiza |
|---|---|
| Kuwunika kwa dera lonse kapena kuchuluka kochepa kwa deta | Kufufuza kamodzi kokha pamene njira yovomerezeka ikukwaniritsa cholinga chozindikira |
| Kusankhana zomera, ulimi kapena kusankhana mitundu ya nthaka | Deta yolumikizidwa ndi ma pol awiri ndi ma cross-polarized kuti muwonjezere zambiri zobalalika |
| Mapu a ayezi a m'nyanja, nyanja kapena kusefukira kwa madzi | Sankhani njira zochokera ku HH- kapena VV malinga ndi gulu, ngodya ya zochitika ndi njira yovomerezeka |
| Kugawa kwapamwamba kapena kuwonongeka kwa kufalikira | Quad-pol yonse ikafunika chidziwitso cha njira zinayi zoyezera gawo |
Njira yabwino kwambiri ndi yokhudzana ndi ntchito. Mainjiniya ayenera kuyerekeza zomwe zili mu chidziwitso ndi kufalikira, kutsimikiza, chiŵerengero cha chizindikiro ndi phokoso, kusinthasintha, nthawi yobwereza, zinthu zogwirira ntchito, komanso kuthekera kowerengera.
Zoganizira za Antena ndi RF pa Polarimetric Radar
Kuyeza kodalirika kwa polarimetric kumadalira zambiri kuposa njira yogwiritsira ntchito. Antena ndi unyolo wa RF ziyenera kukhala ndi magwiridwe antchito okhazikika mu njira zonse ziwiri za polarization. Zofunikira zikuphatikizapo:
- mafupipafupi ogwirira ntchito ndi bandwidth yomweyo;
- kulinganiza bwino kwa phindu ndi mawonekedwe a radiation pakati pa madoko a H ndi V;
- kudzipatula pakati pa anthu ochoka pa doko kupita pa doko ndi kusankhana mitundu;
- kukhazikika kwa matalikidwe ndi gawo;
- VSWR, mawonekedwe olumikizira ndi kuwerengera chingwe;
- Kulinganiza kwa antenna, kuyika geometry ndi malo owunikira calibration.
Zopereka za RF MISOma antenna a nyanga ziwiri, ma antenna a nyanga ya broadband yokhala ndi polarizedndi njira zina zoyankhira ma antenna a RF pa ntchito ya radar, muyeso ndi kuphatikiza makina. Kusankha chitsanzo kuyenera kutengera nthawi zonse deta yomwe ilipo komanso zofunikira zonse zoyeserera.
Mafunso Ofunsidwa Kawirikawiri
Ndi chilembo chiti chomwe chimabwera poyamba mu khodi ya SAR polarization?
Chilembo choyamba chimasonyeza polarization yotumizidwa ndipo chachiwiri chimasonyeza polarization yolandiridwa. HV imatanthauza transmit yopingasa ndi vertical receive.
Kodi kusiyana pakati pa dual-pol ndi quad-pol SAR ndi kotani?
Dual-pol imalemba njira ziwiri, zomwe nthawi zambiri zimakhala HH+HV kapena VV+VH. Quad-pol imalemba HH, HV, VH ndi VV ndipo imasunga ubale wofunikira pakuwunika kwathunthu kwa polarimetric.
Kodi SAR polarization imodzi ndi yabwino nthawi zonse?
Ayi. Njira yothandiza kwambiri imadalira cholinga, kutalika kwa nthawi ya radar, ngodya ya zochitika, njira yodziwira, momwe zinthu zilili komanso cholinga chogwiritsira ntchito.
N’chifukwa chiyani njira zolumikizirana ndi anthu osiyanasiyana zili zothandiza?
HV kapena VH imatha kuwonetsa kufalikira komwe kumasintha kugawanika kwa zochitika, makamaka kufalikira kwa voliyumu ndi zolinga zovuta monga zomera.
Mapeto
Kugawa kwa SAR kumalamulira momwe radar imawunikira chandamale ndi momwe munda wobwezedwa umayezedwera. HH ndi VV ndi njira zogawanitsirana, pomwe HV ndi VH zimagawidwa mosiyanasiyana. Single-pol imapereka magwiridwe antchito, dual-pol imawonjezera kusiyanitsa, ndipo full quad-pol imapereka deta yonse ya polarimetric yolunjika. Zotsatira zolondola zimafuna kuti njira yopezera, dongosolo la antenna, njira yowerengera ndi zofunikira zogwiritsira ntchito ziganiziridwe pamodzi.
Kuti mudziwe kusankha ma antenna kapena thandizo la muyeso wa polarimetric RF, onaninso ma RF MISOkuthekera koyesa antenna or Lumikizanani ndi gulu la RF MISO.
Zolemba ndi Kuwerenga Kowonjezera
Kuti mudziwe zambiri zokhudza ma antenna, chonde pitani ku:
Nthawi yotumizira: Juni-28-2024
