Amasu Okuguqula Isignali Ye-Analog
Ukuguqulwa kwesignali kuyindlela esetshenziswa ukushintsha isici esisodwa noma ngaphezulu segagasi lomthwali ngenhloso yokudlulisa ulwazi. Le ndlela ibaluleke kakhulu ekuxhumaneni kwe-analog, lapho izimpawu zolwazi eziqhubekayo, njengezwi noma ividiyo, ziguqulwa ukuze zivumelane nesiteshi sokuxhumana esitholakalayo.
Ukuguqulwa kwesignali ye-analog kuhlanganisa izindlela eziningana eziyinhloko: ukuguqulwa kwe-amplitude, ukuguqulwa kwemvamisa, kanye nokuguqulwa kwesigaba. Lesi sihloko sizohlola ngayinye yalezi zindlela, kanye nokusetshenziswa kwazo kwezokuxhumana.
1. Ukuguquguquka Kokuphakama (AM)
Izimiso Eziyisisekelo
Ukuguqulwa kwe-Amplitude kuyindlela lapho i-amplitude yegagasi lomthwali ishintshwa khona ukuze ibonise isignali yolwazi. Uma isignali yolwazi inokuguquguquka okukhulu kwe-amplitude, khona-ke igagasi lomthwali lizobhekana nokuguquguquka okukhulu kwe-amplitude.
Izindlela zokusebenza
Ake sithi sinegagasi lokuthwala elivezwa yi-equation:
\[ c(t) = A_c \cos(2πf_c t) \]
Isignali yolwazi okufanele ilungiswe ivezwa kanje:
\[ m(t) \]
Ku-AM, isignali eguquliwe \( s(t) \) iba:
\[ s(t) = [A_c + m(t)] \cos(2πf_c t) \]
Lapha, i-\( A_c \) i-amplitude yegagasi lomthwali kanye ne-\( f_c \) i-frequency yomthwali.
Ukuvelela
– Ubulula: Imiklamo yokudlulisa kanye neyokwamukela ilula kakhulu futhi ayidingi ihadiwe eyinkimbinkimbi.
– Ukusebenza Kahle Komkhawulokudonsa: I-AM isebenzisa umkhawulokudonsa omncane uma kuqhathaniswa nezinye izindlela ezifana ne-FM.
I-Kekurangan
– Ikhwalithi Yomsindo Ephansi: Izwela ukuphazamiseka nomsindo ngoba isignali yolwazi iguqulwa ngesilinganiso esifanayo sesignali.
– Ukusebenza Kahle Kancane Kwamandla: Amandla amaningi angathwali ulwazi ayadluliselwa.
Isicelo
I-AM isetshenziswa kabanzi ekusakazweni komsakazo, ikakhulukazi kumaza e-AM noma amaza aphakathi nendawo (MW).
2. Ukushintshashintsha Kwemvamisa (FM)
Izimiso Eziyisisekelo
Ekushintsheni kwemvamisa, imvamisa yegagasi lomthwali iyashintshwa ngokuya ngesignali yolwazi kuyilapho ubukhulu buhlala bunjalo.
Izindlela zokusebenza
Isiginali yenkampani inikezwa i-equation:
\[ c(t) = A_c \cos(2πf_c t) \]
Isignali yolwazi \( m(t) \) isetshenziselwa ukuguqula imvamisa yenkampani ibe:
\[ s(t) = A_c \cos [2π(f_c + k_f m(t))t] \]
Lapho \( k_f \) kuyinkomba yokuguqulwa kwemvamisa.
Ukuvelela
– Ikhwalithi Yomsindo Ephakeme: Inokumelana okuphezulu nokuphazamiseka kwemvamisa nomsindo, ngakho ikhwalithi yomsindo ingcono kune-AM.
– Ukusebenza Kahle Kakhulu Kwamandla: Amandla aphelele adluliswayo asebenza kahle kakhulu ngoba isignali yolwazi iguqulwa ngokuvama kune-amplitude.
I-Kekurangan
– I-bandwidth Enkulu: Idinga i-bandwidth engaphezu kwe-AM.
– Umklamo Wesistimu Oyinkimbinkimbi Kakhulu: I-transmitter iyinkimbinkimbi kakhulu futhi ivame ukubiza kakhulu.
Isicelo
Ukuguqulwa kwe-FM kusetshenziswa kabanzi ekusakazweni komsakazo we-FM (Frequency Modulation), ekusakazweni kwethelevishini, kanye nasekuxhumaneni kwe-VHF/UHF kwezinsizakalo zokuxhumana ngezwi ezisezingeni eliphezulu.
3. Ukuguqulwa Kwesigaba (PM)
Izimiso Eziyisisekelo
Ekuguqulweni kwesigaba, isigaba segagasi lomthwali siyashintshwa ngokulingana nesignali yolwazi, kanti ubukhulu kanye nemvamisa kuhlala kungaguquki.
Izindlela zokusebenza
Igagasi eliyisisekelo lesithwali:
\[ c(t) = A_c \cos(2πf_c t) \]
Isignali yolwazi \( m(t) \) isetshenziselwa ukuguqula isigaba segagasi lomthwali:
\[ s(t) = A_c \cos [2πf_c t + k_p m(t)] \]
Lapho \( k_p \) kuyinkomba yokuguqulwa kwesigaba.
Ukuvelela
– Umsindo Ongavikelwe Ekwandeni: Umsindo othinta ubukhulu ngeke uthinte isignali eguquliwe, njenge-FM.
– Izinhlelo zokusebenza Ezindaweni Ezihlukahlukene: Zisetshenziswa kwezobuchwepheshe obuningi bokuxhumana kwedijithali.
I-Kekurangan
– I-bandwidth Enkulu: Njenge-FM, i-PM nayo idinga i-bandwidth enkulu.
– Isidingo Somamukeli Oyinkimbinkimbi Kakhulu: Le ndlela idinga umamukeli oyinkimbinkimbi futhi ozwelayo ukuze abone izinguquko zesigaba.
Isicelo
I-PM ivame ukusetshenziswa ekuxhumaneni kwedatha yedijithali njengakubuchwepheshe be-QAM (Quadrature Amplitude Modulation) kanye nasezinhlelweni zokuxhumana ngesathelayithi.
Ukuqhathanisa kanye nesiphetho
– AM: Kulula futhi kusebenza kahle nge-bandwidth kodwa kulula ukuphazanyiswa futhi kusebenza kahle ngamandla aphansi.
– I-FM: I-bandwidth enkulu, ikhwalithi yesignali engcono, futhi imelana kakhulu nomsindo.
– PM: Ayikwazi ukumelana nomsindo we-amplitude futhi isetshenziselwa izinhlelo zokusebenza zedatha yedijithali kodwa idinga i-bandwidth enkulu kanye nokwamukelwa okuyinkimbinkimbi.
Ukukhetha phakathi kwe-AM, FM, kanye ne-PM kuncike kakhulu ezidingweni zohlelo lokusebenza, i-bandwidth etholakalayo, kanye nekhwalithi yesignali oyifunayo. Ayikho indlela eyodwa engcono kakhulu; ngayinye inezinzuzo zayo kanye nokungalungi kwayo okumele kucatshangelwe kumongo wohlelo lokusebenza oluthile.
Amasu okushintshashintsha kwesignali ye-analog adlala indima ebalulekile ezinhlelweni ezahlukene zokuxhumana, enza kube lula ukudluliselwa kolwazi ngamafomethi angatholwa futhi acutshungulwe kalula. Njengoba ubuchwepheshe buthuthuka, ukuguqulwa kwesignali kuyaqhubeka nokukhula, kuhlinzeka ngezixazululo ezisebenza kahle nezisezingeni eliphezulu zokuxhumana komhlaba wonke.
