Nisan sadarwar da tsarin sadarwa mara waya zai iya samu yana samuwa ne ta hanyar abubuwa daban-daban kamar na'urori daban-daban da suka hada da tsarin da yanayin sadarwa. Ana iya bayyana alakar da ke tsakanin su ta hanyar ma'aunin nesa na sadarwa mai zuwa.
Idan ikon watsa na'urar watsa tsarin sadarwa shine PT, ribar eriyar watsawa shine GT, kuma tsawon aiki shine λ. Hankalin mai karɓar na'urar shine PR, karɓar eriya shine GR, kuma nisa tsakanin eriya mai karɓa da watsawa shine R, a cikin nisa na gani da kuma a cikin yanayi ba tare da tsangwama na lantarki ba, dangantaka mai zuwa ta kasance:
PT (dBm) -PR (dBm) + GT (dBi) + GR (dBi) = 20log4pr (m) / l (m) + Lc (dB) + L0 (dB) A cikin dabarar, Lc shine asarar shigarwar ciyarwa na eriya mai watsa tushe; L0 shine asarar igiyar rediyo yayin yaduwa.
Lokacin zayyana tsarin, ya kamata a bar isasshiyar gefe don abu na ƙarshe, asarar yaɗa igiyoyin rediyon L0.
Gabaɗaya, ana buƙatar gefe na 10 zuwa 15 dB lokacin wucewa ta cikin katako da gine-ginen jama'a; ana buƙatar gefe na 30 zuwa 35 dB lokacin wucewa ta ginin gine-ginen da aka ƙarfafa.
Domin 800MH, 900ZMHz CDMA da GSM mitar makada, gabaɗaya an yarda cewa matakin karɓar kofa na wayoyin hannu yana kusan -104dBm, kuma ainihin siginar da aka karɓa yakamata ya zama aƙalla 10dB mafi girma don tabbatar da ƙimar siginar da ake buƙata. A gaskiya ma, don kula da sadarwa mai kyau, ana ƙididdige ikon da aka karɓa sau da yawa kamar -70 dBm. A ɗauka cewa tashar tushe tana da sigogi masu zuwa:
Ikon watsawa shine PT = 20W = 43dBm; ikon karɓar shine PR = -70dBm;
Asarar mai ciyarwa shine 2.4dB (kimanin mai ciyarwa 60m)
Wayar hannu mai karɓar eriya GR = 1.5dBi;
Tsawon tsayin aiki λ = 33.333cm (daidai da mita f0 = 900MHz);
Ma'aunin sadarwa na sama zai zama:
43dBm-(-70dBm)+ GT(dBi)+1.5dBi=32dB+ 20logr(m) dB +2.4dB + hasarar yaduwa L0
114.5dB+ GT(dBi) -34.4dB = 20logr(m)+ hasarar yaduwa L0
80.1dB+ GT(dBi) = 20logr(m)+ hasarar yaduwa L0
Lokacin da darajar gefen hagu na dabarar da ke sama ta fi darajar gefen dama, wato:
GT(dBi)> 20logr(m) -80.1dB+ hasarar yaduwa L0. Lokacin da rashin daidaituwa ya riƙe, ana iya la'akari da cewa tsarin zai iya kula da kyakkyawar sadarwa.
Idan tashar tushe tana amfani da eriyar watsawa ta ko'ina tare da samun GT = 11dBi kuma nisa tsakanin eriya masu watsawa da karɓar shine R=1000m, ƙimar sadarwar ta ƙara zama 11dB>60-80.1dB + asarar yaɗawa L0, wato, lokacin da asarar yaduwa L0, za a iya kiyaye kyakkyawar sadarwa tsakanin kilomita 1.
Karkashin yanayin asarar yaduwa iri ɗaya kamar na sama, idan eriyar watsawa ta sami GT = 17dBi, wato, haɓakar 6dBi, ana iya ninka nisan sadarwa, wato, r = 2 kilomita. Wasu kuma za a iya cire su ta hanya ɗaya. Koyaya, yakamata a lura cewa eriyar tashar tushe tare da samun GT na 17dBi na iya samun ɗaukar hoto mai siffar fan kawai tare da faɗin katako na 30°, 65° ko 90°, da sauransu, kuma ba zai iya kula da ɗaukar hoto na ko'ina ba.
Bugu da ƙari, idan eriya mai watsawa GT = 11dBi ya kasance baya canzawa a lissafin da ke sama, amma yanayin yaduwa ya canza, asarar yaduwa L0 = 31.1dB-20dB = 11.1dB, to, raguwar 20dB yaduwa zai kara yawan nisan sadarwa sau goma, wato, r=10 kilomita. Kalmar asarar yaduwa tana da alaƙa da kewaye da yanayin lantarki. A cikin birane, akwai gine-gine masu tsayi da yawa kuma asarar yaduwa yana da yawa. A cikin yankunan karkarar karkara, gidajen gonaki ba su da yawa kuma ba su da yawa, kuma asarar yaduwa kaɗan ce. Sabili da haka, ko da saitunan tsarin sadarwa sun kasance daidai, iyakar ɗaukar hoto mai tasiri zai bambanta saboda bambancin yanayin amfani.
Don haka, lokacin zabar kowane shugabanci, eriya na jagora da babban riba ko fom ɗin eriya mai ƙarancin riba, ya zama dole a yi la'akari da amfani da eriyar tashar tushe na nau'ikan iri da ƙayyadaddun ƙayyadaddun ƙayyadaddun yanayin hanyar sadarwar wayar hannu da yanayin aikace-aikacen.
Don ƙarin koyo game da eriya, da fatan za a ziyarci:
Lokacin aikawa: Yuli-25-2025
