Rarraba SARyana bayyana yanayin filin lantarki da aka watsa kuma aka karɓa ta hanyar tsarin radar na roba. Saboda saman da tsari daban-daban sun warwatse filayen kwance da tsaye daban-daban, polarization yana ɗaya daga cikin masu canji mafi amfani don fassara hotunan SAR.
Wannan jagorar ta yi bayani game da hanyoyin raba haske guda huɗu masu layi - HH, HV, VH da VV - da kuma hanyoyin samun haske guda uku da aka saba amfani da su: raba haske guda ɗaya, raba haske guda biyu da kuma raba haske gaba ɗaya (quad). Ta kuma bayyana yadda injiniyoyi ke zaɓar yanayi don jin haske daga nesa, gwajin radar da kimanta tsarin eriya.
Menene Rarrabawar SAR?
Yawancin tsarin SAR da ke ɗauke da sararin samaniya suna amfani da layin kwance (H) da na tsaye (V). Lambar tashar mai haruffa biyu tana gano layin kwance da aka watsa da farko sannan layin kwance da aka karɓa na biyu. Misali, HH yana nufin karɓar watsawa ta kwance da na kwance, yayin da HV ke nufin karɓar watsawa ta kwance da na tsaye.
Polarization yana da mahimmanci saboda wani abu da aka yi niyya zai iya kiyaye polarization na abin da ya faru, juya shi ko cire polarization na wani ɓangare na dawowar. Rashin kyawun saman, yanayin ƙasa, halayen dielectric, tsawon rai, kusurwar faruwa da tsarin ciki duk suna tasiri ga backscatter ɗin da aka auna. Saboda haka, ya kamata a fassara polarization tare da mitar mita, yanayin gani da bayanan hoto da aka daidaita.
Menene Ma'anar HH, HV, VH da VV?
| Tashar | Aika | Karɓa | Rarrabawa |
|---|---|---|---|
| HH | Kwance | Kwance | Haɗin gwiwa-ƙasa |
| HV | Kwance | Tsaye | An rarraba shi zuwa sassa daban-daban |
| VH | Tsaye | Kwance | An rarraba shi zuwa sassa daban-daban |
| VV | Tsaye | Tsaye | Haɗin gwiwa-ƙasa |
HH da VV tashoshi ne masu haɗin gwiwa saboda haɗin gwiwa tsakanin watsawa da karɓa iri ɗaya ne. HV da VH tashoshi ne masu haɗin gwiwa saboda haɗin gwiwa tsakanin karɓa yana daidai da haɗin gwiwa tsakanin watsawa. A cikin tsarin monostatic mai daidaitawa, amsoshin HV da VH galibi suna kama da juna, amma duka tashoshi suna riƙe da cikakken ma'aunin polarimetric.
Manyan Yanayin Rarraba SAR guda Uku
1. Rarrabawa Guda Ɗaya
Samun polarization guda ɗaya yana ɗaukar tashoshi ɗaya, galibi HH ko VV. Yana ba da ƙarancin adadin bayanai da sauƙin sarrafawa idan tashar da aka tabbatar ta isa. Iyakar ita ce tashar ɗaya tana ba da ƙarancin bayanai game da hanyoyin watsawa da tsarin manufa.
2. Rarraba Rarrabawa Biyu
Sayen dual-polarization yana tattara tashoshi biyu. Haɗuwa gama gari sun haɗa da HH+HV da VV+VH, inda radar ke watsa polarization ɗaya kuma yana karɓar dawowar co- da cross-polarized. Wasu tsarin kuma suna tallafawa co-pol co-pair kamar HH+VV. Bayanan dual-pol suna ƙara wariya mai amfani yayin da suke kiyaye ƙimar bayanai da buƙatun sarrafawa fiye da cikakken polarimetry. ESA ta bayyana cewa Sentinel-1 tana goyan bayan VV+VH ko HH+HV a cikin tsarin dual-polarization ɗinta.
3. Cikakken Rarrabawa ko Huɗu
Cikakken SAR mai nuna alamun polarimetric yana rubuta HH, HV, VH da VV a matsayin tashoshi masu rikitarwa. Radar mai nuna alamun quad-pol ta gargajiya tana watsa H da V a jere kuma tana karɓar dawowar H da V, tana adana bayanai masu yawa da kuma matakan da suka shafi juna. Wannan yana tallafawa nazarin matrix na warwatsewa da kuma cikakken bayani game da rarrabuwa, rarrabuwa da kuma siffantawa.
Bambancin ya fi rikitarwa a tsarin, buƙatar daidaitawa, yawan bayanai da ƙoƙarin sarrafawa. Dangane da firikwensin, aikin cikakken pol na iya haɗawa da kunkuntar yanki ko ƙuntatawa daban-daban na saye. Ƙaramin polization wani ingantaccen tsarin SAR ne, amma ya bambanta da yanayin layi na gargajiya guda ɗaya, biyu- da huɗu-pol da aka tattauna a nan.
Haɗin gwiwa vs. Haɗin gwiwa
Tashoshin da aka haɗa da polarized sau da yawa suna adana riba mai ƙarfi daga saman da sifofi waɗanda ke kula da polarization da aka watsa. Ribobin da aka haɗa da polarized sun nuna cewa tsarin warwatsewa ya canza wani ɓangare na yanayin polarization ta hanyar watsawa da yawa, tunani da yawa, yanayin lissafi mai rikitarwa ko tsarin anisotropic.
- Ruwa mai natsuwa da saman da ke da santsi:sau da yawa suna bayyana duhu lokacin da yawancin kuzarin ke nunawa nesa da radar; rashin ƙarfi, iska da kusurwar faruwa na iya ƙara yawan watsawa.
- Kayan lambu:rassan, ganyaye da ganye suna haifar da watsawar girma, don haka hanyoyin haɗin gwiwa na iya ƙara mahimman bayanai game da tsarin.
- Yankunan birane:Gine-gine da saman ƙasa na iya samar da sakamako mai ƙarfi na haɗin gwiwa da kuma watsawa sau biyu, ya danganta da yanayin da aka tsara da kuma yanayin hoto.
- Ƙasa, dusar ƙanƙara da kankara:danshi, ƙaiƙayi, zurfi, tsawon tsayi da kuma tsarin ciki duk suna shafar amsawar polarization.
Waɗannan ƙa'idodi ne na fassara maimakon ƙa'idodi na duniya baki ɗaya. Bai kamata a zaɓi tashar ba tare da la'akari da hanyar radar ba, kusurwar faruwa, ƙuduri, yanayi da ingancin daidaitawa.
Yadda Ake Zaɓar Yanayin Rarraba SAR
| Bukatar | Wurin farawa mai amfani |
|---|---|
| Sa ido mai faɗi ko ƙarancin adadin bayanai | Manya ɗaya idan tashar da aka tabbatar ta cika burin ganowa |
| Wariyar launin fata game da kayan lambu, noma ko kuma mallakar filaye | Bayanan haɗin gwiwa biyu-pol da na haɗin gwiwa-polarized don ƙarin bayanan warwatsewa |
| Taswirar kankara, teku ko ambaliyar ruwa | Zaɓi hanyoyin HH- ko VV dangane da band, kusurwar faruwa da kuma hanyar da aka tabbatar |
| Rarrabawa mai zurfi ko warwatsewa | Cikakken quad-pol lokacin da ake buƙatar bayanin tashoshi huɗu da aka daidaita a lokaci-lokaci |
Mafi kyawun yanayin aiki shine na musamman ga aikace-aikace. Injiniyoyi ya kamata su kwatanta abubuwan da ke cikin bayanai da ɗaukar hoto, ƙuduri, rabon sigina zuwa hayaniya, swath, lokacin sake dubawa, albarkatun sarrafawa da ikon daidaitawa.
Abubuwan da ake la'akari da su na Eriya da RF don Radar Polarimetric
Ma'aunin polarimetric mai inganci ya dogara ne akan fiye da tsarin sarrafawa. Eriya da sarkar RF dole ne su kiyaye ingantaccen aiki a cikin tashoshin polarization guda biyu. Ma'auni masu mahimmanci sun haɗa da:
- mitar aiki da bandwidth nan take;
- daidaiton riba da tsarin radiation tsakanin tashoshin H da V;
- Warewa daga tashar jiragen ruwa zuwa tashar jiragen ruwa da kuma nuna wariya tsakanin yankuna daban-daban;
- girma da kwanciyar hankali na lokaci;
- VSWR, hanyar haɗin haɗi da daidaita kebul;
- Daidaita eriya, tsarin hawa da kuma tsarin daidaitawa.
Kayayyakin RF MISOEriya mai ƙaho mai rassa biyu, eriya mai ƙaho mai girman polarized guda biyuda sauran hanyoyin magance matsalar eriya ta RF don aikin radar, aunawa da haɗa tsarin. Ya kamata zaɓin samfura koyaushe ya dogara ne akan takardar bayanai ta yanzu da cikakken buƙatar gwaji.
Tambayoyin da Ake Yawan Yi
Wace harafi ce ta fara fitowa a cikin lambar SAR polarization?
Harafin farko yana gano rarrabuwar da aka watsa, na biyu kuma yana gano rabuwar da aka karɓa. HV yana nufin watsawa a kwance da karɓa a tsaye.
Mene ne bambanci tsakanin dual-pol SAR da quad-pol SAR?
Dual-pol yana rikodin tashoshi biyu, galibi HH+HV ko VV+VH. Quad-pol yana rikodin HH, HV, VH da VV kuma yana kiyaye alaƙar da ake buƙata don cikakken nazarin polarimetric.
Shin ɗaya daga cikin polarization na SAR koyaushe shine mafi kyau?
A'a. Yanayin da ya fi amfani ya dogara ne da abin da aka nufa, tsawon radar, kusurwar faruwa, ƙuduri, yanayin muhalli da kuma manufar sarrafawa.
Me yasa hanyoyin sadarwa na cross-pol suke da amfani?
HV ko VH na iya bayyana warwatsewar da ke canza rarrabuwar kawuna, musamman warwatsewar girma da kuma abubuwan da suka shafi tsari kamar ciyayi.
Kammalawa
Tsarin rarraba bayanai na SAR yana sarrafa yadda radar ke haskaka manufa da kuma yadda ake auna filin da aka dawo da shi. HH da VV tashoshi ne masu haɗakar polarized, yayin da HV da VH suna haɗuwa da polarized. Tsarin raba bayanai na pol guda ɗaya yana ba da inganci, tsarin raba bayanai na dual-pol yana ƙara wariya, kuma cikakken tsarin raba bayanai na quad-pol yana ba da cikakken cikakken tsarin tattara bayanai na polarimetric. Sakamakon da ya dace yana buƙatar yanayin siye, tsarin eriya, hanyar daidaitawa da buƙatun aikace-aikace don a yi la'akari da su tare.
Don zaɓar eriya ko tallafin auna RF na polarimetric, duba RF MISOsGwajin eriya iya aiki or tuntuɓi ƙungiyar RF MISO.
Nassoshi da Karatu Mai Zurfi
Don ƙarin koyo game da eriya, da fatan za a ziyarci:
Lokacin Saƙo: Yuni-28-2024
