Mehlala ea Lipotso mabapi le Puisano ea Maqhubu a Seea-le-moea
Maqhubu a seea-le-moea ke mofuta oa mahlaseli a motlakase a sebetsang puisanong ea waelese. Ka maqhubu a tlohang ho kilohertz (kHz) tse 'maloa ho isa ho gigahertz (GHz) tse 'maloa, maqhubu a seea-le-moea a sebelisoa lits'ebetsong tse fapaneng - ho tloha likhasong tsa seea-le-moea le thelevishene ho ea litsamaisong tsa puisano tsa selefounu. Sehloohong sena, re tla tšohla mehlala ea maqhubu a seea-le-moea le litlhaloso tsa 'ona ho re thusa ho utloisisa melao-motheo le ts'ebeliso ea maqhubu ana bophelong ba letsatsi le letsatsi.
Mohlala oa Potso ea 1: Maqhubu le Bolelele ba Maqhubu
Potso:
Seteishene sa seea-le-moea se fetisa maqhubu a seea-le-moea ka maqhubu a 100 MHz. Bala bolelele ba leqhubu. (Lebelo la khanya ke 3 x 10^8 m/s.)
Puisano:
Maqhubu (f) le bolelele ba maqhubu (λ) a maqhubu a motlakase a amana le lebelo la khanya (c) ka har'a equation:
\[ c = f \times \lambda \]
Moo:
– \( c \) = lebelo la khanya (3 x 10^8 m/s)
– \( f \) = maqhubu (100 MHz kapa 100 x 10^6 Hz)
– \( \lambda \) = bolelele ba leqhubu (bo ka fumanwang)
Ho tsoa ho equation e kaholimo, bolelele ba leqhubu bo ka baloa ka:
\[ \lambda = \frac{c}{f} \]
Kahoo:
\[ \lambda = \frac{3 \times 10^8}{100 \times 10^6} = 3 \ \text{meter} \]
Kahoo, bolelele ba maqhubu a 100 MHz ke limithara tse 3.
Mohlala oa Potso ea 2: Matla a Phetiso le Matla
Potso:
Sesebediswa sa radio sa 50-watt se ntsha maqhubu a radio ka tsela e iketsang (ka ho tshwana mahlakoreng ohle). Bala matla a maqhubu a radio bohole ba dimithara tse 10 ho tloha sesebedisweng.
Puisano:
Matla (I) a leqhubu le ntshwang ka isotropic a ka balwa ka:
\[ I = \frac{P}{A} \]
Moo:
– \( P \) = matla a ho fetisa (50 watts)
– \( A \) = sebaka se ka holimo sa lesaka (4πr^2)
Sebaka se ka holimo sa bolo ke (r) = limithara tse 10.
\[ A = 4\pi (10)^2 = 400\pi \]
Kahoo:
\[ I = \frac{50}{400\pi} = \frac{1}{8\pi} \ \text{watt/m}^2 \]
Kahoo, matla a maqhubu a seea-le-moea a bohōle ba limithara tse 10 ho tloha ho transmitter ke \( \frac{1}{8\pi} \) watt/m².
Mohlala oa Potso ea 3: Bokhoni ba Bandwidth le Channel
Potso:
Kanale ea puisano e na le bandwidth ea 20 MHz. Haeba u sebelisa modulation ea QPSK (Quadrature Phase Shift Keying), bokhoni bo boholo ba kanale ke bofe?
Puisano:
Modulation ea QPSK e na le mekhahlelo e 4 e fapaneng, kahoo e ka fetisa li-bit tse 2 ka letšoao ka nako e le 'ngoe.
Palo ea matšoao ka motsotsoana ao bandwidth ea 20 MHz e ka a sebetsanang ke:
\[ \mongolo{Letshwao} = 20 \makgetlo a 10^6 \ \mongolo{letshwao/motsotswana} \]
Kaha QPSK e romela di-bit tse 2 ka letshwao, bokgoni kapa palo ya di-bit ka motsotsoana (bitrate) ke:
\[ \text{Bitrate} = 20 \times 10^6 \times 2 = 40 \ \text{Mbps} \]
Kahoo, bokgoni bo phahameng ba kanale ke 40 Mbps.
Mohlala oa Potso ea 4: Tšitiso le Tšitiso
Potso:
Sehahi sa radio se nang le maqhubu a 101.1 MHz se thulana le tšitiso ho tsoa ho sehahi se seng se nang le maqhubu a 101.3 MHz. Bala maqhubu a beat a hlahang.
Puisano:
Maqhubu a ho otla \( f_{beat} \) a hlaha ka lebaka la phapang pakeng tsa maqhubu a mabedi a haufi mme a ka balwa ka:
\[ f_{beat} = |f_1 – f_2| \]
Moo:
– \( f_1 \) = 101.1 MHz
– \( f_2 \) = 101.3 MHz
Kahoo:
\[ f_{beat} = |101.1 – 101.3| = | -0.2 | = 0.2 \ \mongolo{MHz} \]
Kahoo, maqhubu a hlahang ke 0.2 MHz.
Mohlala oa Potso ea 5: Tšusumetso ea Doppler Maqhubung a Seea-le-moea
Potso:
Seteishene sa seea-le-moea se hasanya maqhubu a 95 MHz. Sefofane se atamela seteishene sa seea-le-moea ka lebelo la 340 m/s. Bala maqhubu a amoheloang ke sefofane haeba lebelo la maqhubu a seea-le-moea le lekana le lebelo la khanya (3 x 10^8 m/s).
Puisano:
Tšusumetso ea Doppler bakeng sa maqhubu a seea-le-moea e ka hlalosoa ka tsela ena:
\[ f_{amohela} = f_{0} \left(\frac{c + v}{c}\right) \]
Moo:
– \( f_0 \) = maqhubu a pele (95 MHz)
– \( v \) = lebelo la sefofane (340 m/s)
– \( c \) = lebelo la maqhubu (3 x 10^8 m/s)
Kahoo:
\[ f_{amohela} = 95 \ka makhetlo a 10^6 \ka ho le letšehali(\frac{3 \ka makhetlo a 10^8 + 340}{3 \ka makhetlo a 10^8}\ka ho le letona) \]
\[ f_{amohela} = 95 \ka makhetlo a 10^6 \ka ho le letšehali(\frac{3 \ka makhetlo a 10^8 + 3.4 \ka makhetlo a 10^2}{3 \ka makhetlo a 10^8}\ka ho le letona) \]
\[ f_{amohela} \hoo e ka bang 95 \ka makhetlo a 10^6 \ka ho le letšehali(1 + \ka ho le letona{3.4 \ka makhetlo a 10^2}{3 \ka makhetlo a 10^8}\ka ho le letona) \]
\[ f_{amohela} \hoo e ka bang 95 \ka makhetlo a 10^6 \ka ho le letšehali(1 + 1.1333 \ka makhetlo a 10^{-6}\ka ho le letona) \]
\[ f_{amohela} \hoo e ka bang 95 \makgetlo a 10^6 \makgetlo a 1.0000011333 \]
\[ f_{amohela} \hoo e ka bang 95.000107 \ \mongolo{MHz} \]
Kahoo, maqhubu a amoheloang ke sefofane se atamelang ke a ka bang 95.000107 MHz.
Ho koala
Ho utloisisa melao-motheo ea motheo le mekhoa ea lipalo ea maqhubu a seea-le-moea ho bohlokoa masimong a fapaneng a boenjiniere le saense. Mathata a kaholimo a fana ka mehlala e meng ea kamoo fisiks ea maqhubu a seea-le-moea e ka sebelisoang kateng maemong a fapaneng a sebetsang. Tsela e lebisang kutloisisong e tebileng ke ka ho ikoetlisa ka mokhoa o tsitsitseng le ho hlahloba lits'ebetso tsa 'nete tsa maqhubu a seea-le-moea theknolojing ea puisano eo re e sebelisang letsatsi le letsatsi.
