IsiGaba kwezwi njengendlela yokosulela data

Njengoko yaziwa, uphawu RF iquka carrier, olusekelwe phezu amaza erediyo ngohlobo ezilula oscillation harmonic u (t) = cos U ( ωt + φ). Kulo kulandela ukuba uphawu carrier kwamaza, kukho elizimeleyo parameters ezintathu, echaphazela yamanyala apho ukutshintsha uphawu yolawulo.

Oku kuthetha ithuba iindidi ezintathu: awo (AM), njalo (FM) kunye isigaba kwezwi (PM).

Phase kwezwi - indlela yokudlulisela analog okanye inkcazelo enkcazelo ngokutshintsha angle lokuqala (isigaba) φ ₀ rhoqo carrier yomqondiso ngesondo.

Xa ngezigaba φ (t) kuxhomekeke kulawulo awo (kwezwi) umqondiso, ngamanye amazwi, φ (t) = ω _{0 t} + _Δ φ _∙ sinΩt + φ ₀ = = φ _{0 +} ke (t), apho k - ukulingana factor.

Uphawu Isigaba-modulated jikelele ocaciswe ibinzana u (t) = U _n isono [ωt + φ (t)].

Xa elinye ithoni kwezwi [e (t) = E isono Ωt] siye: φ (t) = φ ₀ + ke isono Ωt = φ ₀ + Δφ _max isono Ωt.

Emva kokuba kufakwe amaxabiso φ (t) kwi lenxaki yomqondiso kwisigaba-modulated sinokuyifumana u (t) = U _n nesono (ω _n t + φ ₀ + Δφ _max isono Ωt), apho Δφ _max - utshintsho ubuninzi kwisigaba ngokomlinganiselo awo le ombane yolawulo. Δφ _max ebizwa isalathiso kwezwi engile luchazwa yi m.

Njengoko kubonakala, xa m FM = Δφ _max = ke. Ixabiso leso ngexesha-ezahlukahlukeneyo isigaba engile Θ (t) uyalingana Θ (t) = ω _n t + φ ₀ + msin Ωt, ukuze ω = d Θ (t) / dt = ω _n + mΩ cosΩt, apho mΩ = Δφ _max ω = Δ ω _n = kEΩ - ubuninzi sokuquqa ukutenxa for FM ω _n, kuba umlinganiselo ngqo awo kunye amaza oscillation modulating.

Ngoko, xa FM index kwezwi eziphawula utshintsho isigaba obukhulu ngokomlinganiselo umqondiso ulawulo awo kwaye akuxhomekekanga kwi-frequency kwezwi. Amaza ukwahluka malunga imin (ecaleni) yi kisekiyo ngqo awo kunye amaza ombane modulating.

Kuxhomekeka kwisigaba isicelo kwezwi na iintlobo eziliqela. Omnye wabo, ingakumbi, i ezineSigaba umehluko Shift Keying.

Kule fomu, kuxhomekeke umqondiso modulating yohluka kuphela sigaba umqondiso, kwaye rhoqo kunye namandla awo kuhlala rhoqo. Xa ixabiso ulwazi RPM ayikho utshintsho kwisigaba elililo, yaye ukwahluka lwayo ngokubhekiselele kumaxabiso odlulileyo.

wesekethe Electronic, nto leyo ebangela utshintsho kwisigaba engile le oscillation modulated (xa kuthelekiswa yenethiwekhi unmodulated) ngokungqinelana uphawu modulating kuthiwa kwisigaba modulator.

Developed iintlobo ezininzi zemifanekiso. Scheme modulator elula iqulathe varicap - diode ekwaziyo phantsi isiphumo eziguquguqukayo capacitance ulawulo ombane kuhlangana. Xa eli cebo, modulating le ombane lutshintsha amandla varicap. Isigaba Utshintsho ixhomekeke ubukhulu wayesisalamane diode capacitance kunye R. ukumelana umthwalo

Ngoko ke, lo shift kuxhomekeka ombane kwezwi. Oku kubanga sisigaba kwezwi yomqondiso radio. Noko ke, ukutshintsha eso sinxulumana nonlinear modulating ombane varicap capacitance lihlobene ombane modulating nonlinear ukuba kudala iingxaki ongezelekileyo kwi modulators kwisigaba sokwakha.

Isigaba Pure kwezwi iye akafunyanelwanga isicelo ebanzi ngokwaneleyo ngenxa osingelo-zayo ezinkulu - phantsi nezifo ingxolo.