Tambayoyi Misali akan Tattaunawar Wayoyin Rediyo
Raƙuman rediyo nau'i ne na hasken lantarki wanda ke aiki a cikin sadarwa mara waya. Tare da mitoci daga 'yan kilohertz (kHz) zuwa gigahertz da yawa (GHz), ana amfani da raƙuman rediyo a cikin aikace-aikace iri-iri - daga watsa shirye-shiryen rediyo da talabijin zuwa tsarin sadarwa ta wayar salula. A cikin wannan labarin, za mu tattauna misalan raƙuman rediyo da bayaninsu don taimaka mana mu fahimci ƙa'idodi da aikace-aikacen waɗannan raƙuman a rayuwar yau da kullun.
Misali Tambaya ta 1: Mita da Tsawon Zango
Tambaya:
Tashar rediyo tana watsa raƙuman rediyo a mita na 100 MHz. Lissafa tsawon tsayin haske. (Saurin haske shine 3 x 10^8 m/s.)
Tattaunawa:
Mita (f) da tsawon rai (λ) na raƙuman lantarki suna da alaƙa da saurin haske (c) ta hanyar lissafi:
\[c = f \times \lambda \]
Ina:
– \( c \) = saurin haske (3 x 10^8 m/s)
– \( f \) = mita (100 MHz ko 100 x 10^6 Hz)
– \( \lambda \) = tsawon rai (za a samu)
Daga lissafin da ke sama, ana iya ƙididdige tsawon tsayi ta hanyar:
\[ \lambda = \frac{c}{f} \]
Don haka:
\[ \lambda = \frac{3 \sau 10^8}{100 \sau 10^6} = 3 \ \text{mita} \]
Don haka, tsawon mita 100 MHz shine mita 3.
Misali Tambaya ta 2: Ƙarfin Watsawa da Ƙarfinsa
Tambaya:
Mai watsa rediyo mai watt 50 yana fitar da raƙuman rediyo ta hanyar isotropic (a kowane bangare). A ƙididdige ƙarfin raƙuman rediyo a nisan mita 10 daga mai watsawa.
Tattaunawa:
Ana iya ƙididdige ƙarfin (I) na raƙuman da ke fitowa ta hanyar isotropic ta hanyar:
\[ I = \frac{P}{A} \]
Ina:
– \( P \) = ƙarfin watsawa (watts 50)
– \( A \) = yankin saman ƙwallo (4πr^2)
A nesa (r) = mita 10, saman ƙwallon shine:
\[A = 4\pi (10)^2 = 400pi \]
Don haka:
\[ I = \frac{50}{400\pi} = \frac{1}{8\pi} \ \text{watt/m}^2 \]
Don haka, ƙarfin raƙuman rediyo a nisan mita 10 daga mai watsawa shine watt/m².
Misali Tambaya ta 3: Ƙarfin Bandwidth da Tashar
Tambaya:
Tashar sadarwa tana da bandwidth na 20 MHz. Idan ana amfani da tsarin QPSK (Quadrature Phase Shift Keying), menene matsakaicin ƙarfin tashar?
Tattaunawa:
Tsarin QPSK yana da matakai 4 daban-daban, don haka yana iya aika rago 2 a kowace alama a cikin lokaci ɗaya.
Adadin alamomi a kowace daƙiƙa da bandwidth na 20 MHz zai iya ɗauka shine:
\[ \text{Symbol} = 20 \sau 10^6 \ \text{symbol/second} \]
Tunda QPSK yana aika bit 2 a kowace alama, ƙarfin ko adadin bit a kowace daƙiƙa (bitrate) shine:
\[ \text{Bitrate} = 20 \times 10^6 \times 2 = 40 \ \text{Mbps} \]
Saboda haka, matsakaicin ƙarfin tashar shine 40 Mbps.
Misali Tambaya ta 4: Shisshigi da Damuwa
Tambaya:
Mai watsa rediyo a mita 101.1 MHz yana fuskantar tsangwama daga wani mai watsa rediyo a mita 101.3 MHz. Lissafa mitar bugun da aka samu.
Tattaunawa:
Mitar bugun \( f_{beat} \) tana faruwa ne saboda bambancin da ke tsakanin mitoci biyu masu kusa kuma ana iya ƙididdige ta ta:
\[ f_{beat} = |f_1 – f_2| \]
Ina:
– \( f_1 \) = 101.1 MHz
– \( f_2 \) = 101.3 MHz
Don haka:
\[ f_{beat} = |101.1 – 101.3| = | -0.2 | = 0.2 \ \rubutu{MHz} \]
Saboda haka, mitar bugun da aka samu shine 0.2 MHz.
Misali Tambaya ta 5: Tasirin Doppler a cikin Radiyo Waves
Tambaya:
Tashar rediyo tana watsawa a mitar 95 MHz. Jirgin sama yana kusantar tashar rediyon a gudun mita 340/s. Lissafa mitar da jirgin sama ya karɓa idan saurin raƙuman rediyon ya yi daidai da saurin haske (3 x 10^8 m/s).
Tattaunawa:
Ana iya bayyana tasirin Doppler ga raƙuman rediyo kamar haka:
\[ f_{accept} = f_{0} \left(\frac{c + v}{c}\right) \]
Ina:
– \( f_0 \) = mitar asali (95 MHz)
– \( v \) = gudun jirgin sama (m340/s)
– \( c \) = saurin raƙuman ruwa (3 x 10^8 m/s)
Don haka:
\[ f_{accept} = 95 \sau 10^6 \left(\frac{3 \sau 10^8 + 340}{3 \sau 10^8}\dama) \]
\[ f_{accept} = 95 \sau 10^6 \left(\frac{3 \sau 10^8 + 3.4 \sau 10^2}{3 \sau 10^8}\dama) \]
\[ f_{accept} \approx 95 \sau 10^6 \left(1 + \frac{3.4 \sau 10^2}{3 \sau 10^8}\dama) \]
\[ f_{accept} \approx 95 \sau 10^6 \left(1 + 1.1333 \sau 10^{-6}\right) \]
\[ f_{accept} \approx 95 \sau 10^6 \sau 1.0000011333 \]
\[ f_{accept} \approx 95.000107 \ \text{MHz} \]
Don haka, mitar da jirgin sama ke samu tana kusan 95.000107 MHz.
Penutup
Fahimtar ƙa'idodi na asali da tsarin lissafi na raƙuman rediyo yana da mahimmanci a fannoni daban-daban na injiniyanci da kimiyya. Matsalolin da ke sama sun ba da wasu misalai na yadda za a iya amfani da kimiyyar kimiyyar rediyo a cikin yanayi daban-daban na aiki. Hanya zuwa zurfafa fahimta ita ce ta hanyar yin aiki akai-akai da kuma bincika aikace-aikacen raƙuman rediyo na gaske a cikin fasahar sadarwa da muke amfani da su kowace rana.
