Isignali edluliswa ngekhebula lenethiwekhi kamabonakude iyi-broadband, i-spectrum ehlukaniswe ngamafrikhwensi. Amapharamitha esignali, okuhlanganisa amaza nezinombolo zesiteshi eRussia alawulwa yi-GOST 7845-92 ne-GOST R 52023-2003, kodwa opharetha ukhululekile ukukhetha okuqukethwe kwesiteshi ngasinye ngokubona kwakhe.
Okuqukethwe ochungechungeni lwezihloko
- Ingxenye 2: Ukwakheka kwesignali kanye nokuma
- Ingxenye 3: Ingxenye Yesiginali ye-Analogi
- Ingxenye 4: Ingxenye Yesiginali Yedijithali
- Ingxenye 5: Inethiwekhi yokusabalalisa i-coaxial
- Ingxenye 6: Izikhulisi Zesiginali ye-RF
- Ingxenye 7: Abamukeli be-Optical
- Ingxenye 8: Inethiwekhi ye-Optical backbone
- Ingxenye 9: Isihloko
- Ingxenye 10: Ukuxazulula inkinga inethiwekhi ye-CATV
Ake nginikhumbuze ukuthi angibhali incwadi yokufunda, kodwa ngiwuhlelo lokufundisa lokwandisa ulwazi lwami futhi ngingene emhlabeni we-cable TV. Ngakho-ke, ngizama ukubhala ngolimi olulula, ngishiya amagama angukhiye kulabo abanesithakazelo futhi abangangeni ngokujulile ekuchazeni ubuchwepheshe obuchazwe ngokuphelele izikhathi ezingamakhulu ngaphandle kwami.
Sikala ngani?
Ochwepheshe bethu ngokuyinhloko basebenzisa i-Deviser DS2400T ukuze bathole ulwazi lwesignali kumakhebula angama-coaxial.
Empeleni lesi yisamukeli sikamabonakude, kodwa esikhundleni sesithombe nomsindo, sibona izici zobuningi nekhwalithi zazo zombili i-spectrum kanye namashaneli angawodwana. Imifanekiso elandelayo yizithombe-skrini ezisuka kule divayisi.
Le Devisor inokusebenza okungafuneki ngandlela-thile, kodwa kukhona nezisetshenziswa ezipholile nakakhulu: ezinesikrini esibonisa isithombe se-TV ngokuqondile, ithola isignali yokubona kanye, lokho iDevayitha ekushodayo, ithola isignali yesathelayithi ye-DVB-S (kodwa leyo indaba ehluke ngokuphelele) .
I-spectrum yesignali
Imodi yokubonisa i-spectrum ikuvumela ukuthi uhlole ngokushesha isimo sesignali "ngeso"
Kule modi, idivayisi iskena amashaneli ngokuhambisana nohlelo olushiwo lwamafrikhwensi. Ukuze kube lula, amaza angasetshenziswanga kunethiwekhi yethu asusiwe ku-spectrum egcwele, ngakho isithombe esiwumphumela siwuhlaka lwamashaneli.
Iziteshi zedijithali zikhonjiswe ngokuluhlaza okwesibhakabhaka, iziteshi ze-analogue ziphuzi. Ingxenye eluhlaza yesiteshi se-analog ingxenye yayo yomsindo.
Umehluko emazingeni eziteshi ezihlukene ubonakala ngokucacile: ukungalingani komuntu ngamunye kuncike kuzilungiselelo zama-transponders kusihloko, futhi umehluko ojwayelekile phakathi kwamafrikhwensi aphezulu naphansi anencazelo ethile, engizoxoxa ngayo ngezansi.
Kule modi, ukuphambuka okunamandla okuvela kokujwayelekile kuzobonakala ngokucacile, futhi uma kunezinkinga ezinkulu kunethiwekhi, lokhu kuzobonakala ngokushesha. Isibonelo, esithombeni esingenhla ungabona ukweqiwa kwamashaneli amabili edijithali endaweni yefrikhwensi ephezulu: akhona kuphela ngesimo semigqa emifushane, afinyelelanga ezingeni lika-10 dBΒ΅V (izinga lesithenjwa lika-80 dBΒ΅V libonisiwe. phezulu - lona umkhawulo ongaphezulu wegrafu), empeleni okuwumsindo intambo ewuthola ngokwawo njengothi noma onikelwe okokusebenza okusebenzayo. Lezi ziteshi ezimbili ziyiziteshi zokuhlola futhi bezicishiwe ngesikhathi sokubhala.
Ukusatshalaliswa okungalingani kwamashaneli edijithali ne-analog kungabangela ukudideka. Lokhu, yiqiniso, akulungile futhi kwenzeka ngenxa yokuthuthukiswa kokuziphendukela kwenethiwekhi: iziteshi ezengeziwe zamane zengezwa ohlelweni lwemvamisa engxenyeni yamahhala ye-spectrum. Lapho udala uhlelo lokuvama ukusuka ekuqaleni, kungaba okulungile ukubeka yonke i-analog ekugcineni engezansi yesibonisi. Ngaphezu kwalokho, imishini yesiteshi eyenzelwe ukukhiqiza isignali emazweni aseYurophu inemikhawulo ekusetshenzisweni kwamafrikhwensi okusakaza isignali yedijithali futhi, nakuba kungekho mingcele enjalo ezweni lethu, ukusebenzisa imishini enjalo kuyadingeka ukubeka iziteshi zedijithali ku-spectrum. , ngokuphambene nengqondo.
I-Waveform
Njengoba kwaziwa ku-fundamental physics, lapho igagasi liphezulu imvamisa, yilapho liqina khona lapho lisabalala. Lapho udlulisa isignali ye-broadband efana naleyo etholakala kunethiwekhi ye-CATV, ukuncipha kunethiwekhi yokusabalalisa kungafinyelela amashumi ama-decibel ngengalo ngayinye, futhi engxenyeni engezansi ye-spectrum kuyoba ngaphansi izikhathi ezimbalwa. Ngakho-ke, ngemva kokuthumela isignali engaguquki kusikhuphukeli esivela esitezi esingaphansi, esitezi sama-25 sizobona into efana nalena elandelayo:
Izinga lamafrikhwensi aphezulu liphansi ngokuphawulekayo kunalawa aphansi. Esimeni sangempela, i-TV, ngaphandle kokuyiqonda, ingase icabangele iziteshi ezibuthakathaka njengomsindo futhi izihlunge. Futhi uma i-amplifier efakwe efulethini, khona-ke lapho uzama ukuyilungiselela ukwamukela izinga eliphezulu lamashaneli kusuka engxenyeni engenhla yobubanzi, ukukhulisa kakhulu kuzokwenzeka engxenyeni engezansi. Amazinga asho umehluko ongekho ngaphezu kuka-15 dBΒ΅V kulo lonke ububanzi.
Ukuze ugweme lokhu, lapho ulungiselela okokusebenza okusebenzayo, izinga eliphezulu liqale libekwe endaweni yefrikhwensi ephezulu. Lokhu kubizwa ngokuthi "ukutsheka okuqondile", noma "ukutsheka". Futhi okuboniswa esithombeni "i-reverse tilt", futhi isithombe esinjalo sesivele sengozi. Noma, okungenani, inkomba yokuthi kunenkinga ngekhebula endaweni yokulinganisa.
Isimo esiphambene naso siyenzeka, lapho amafrikhwensi aphansi engekho, futhi angaphezulu angangeni kakhulu ngaphezu kwezinga lomsindo:
Lokhu kusitshela futhi ngomonakalo wekhebula, okuwumgogodla wayo omaphakathi: lapho imvamisa iphakeme, isondela eduze konqenqema lwe-waveguide esakaza (umphumela wesikhumba kukhebula eliqinile). Ngakho-ke, sibona lezo ziteshi kuphela ezisatshalaliswa kumafrikhwensi aphezulu, kodwa, njengomthetho, i-TV ngeke isakwazi ukuyithola kuleli zinga.
Source: www.habr.com