Inqubekelaphambili ithuthuka emhlabeni wonke, kodwa, ngeshwa, ayisheshi ngendlela esingathanda ngayo. Ngakho-ke, okwamanje, izigidi zamathelevishini azikwazi ukuthola isignali yedijithali ngaphandle kwezinduku, futhi umhlinzeki okhathalela ukunethezeka kobhalisile kufanele anikeze isignali ye-TV futhi ngefomu le-analog.
Okuqukethwe ochungechungeni lwezihloko
- 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
Uhlelo lombuso lokuvala ukusakazwa kwe-analogue eziteshini ze-TV
Nakuba lokhu kungahlobani ngokugcwele nesihloko, akwenzeki nje ukuyiziba indaba evutha njalo manje.
Ngakho: zonke lezi zingxoxo ziphathelene nokusakaza kuphela. Okusho ukuthi, isignali ehamba emoyeni isuka embhoshongweni we-TV oseduze. Umbuso kuphela onesibopho salesi siginali eRussia, futhi amabili kuphela (kwezinye izifunda ezintathu) ama-multiplex azohlala kuwo. Ingxenye ye-analog yokusakaza ngekhebula incike kuphela kubahlinzeki futhi cishe ngeke ihambe. Ngakho-ke uma i-TV yakho ingaxhunyiwe ku-antenna ebekwe ophahleni lwendlu noma efasiteleni, khona-ke lokhu kucisha ngeke kukuthinte. Kungani ngithi “cishe” futhi “cishe”? Iqiniso liwukuthi abanye opharetha bezintambo sebevele bamemezele ukumiswa okuzayo kokuhlinzeka ngezimpawu ze-analog kubabhalisi. Kunzima ukuqonda isisusa, ngoba njengoba kusobala eNgxenyeni yoku-1 yezindatshana zami, lokhu akukwazi ukuletha ukonga okukhulu emishinini: amakhadi ambalwa kuphela okunweba ku-chassis evamile anesibopho salokhu. Ukukhulula amafrikhwensi enkampani yenethiwekhi nakho kuyisisusa esingabazisayo: asikho isidingo emakethe samashaneli amaningi kangaka edijithali angahlaliswa ukuze athathe indawo ye-analogue ekhubazekile. Okuwukuphela kwendlela yokwenza imali lapha iwukudayisela ababhalisile amabhokisi e-set-top, kodwa lokho sizokushiya kunembeza wabasebenzi.
Amapharamitha esignali ye-Analog
Isignali kamabonakude we-analogi iyisamba samasiginali amathathu: ukukhanya okushintshiwe kwe-amplitude nombala, nomsindo oguquliwe. Kodwa ukuhlola ubuningi nekhwalithi, kwanele ukuthatha lesi siginali njengento eyodwa, nakuba sonke siye saqaphela izikhathi ezingaphezu kwesisodwa ukuthi ngisho nesithombe esibi, umsindo ovela ku-TV muhle. Lokhu kungenxa yokungavikeleki komsindo okungcono kwe-FM. Ukuze ulinganise amapharamitha esignali ye-analog, idivayisi ye-Deviser DS2400T inikeza imodi elandelayo:
Kule modi, ungasebenzisa izinkinobho ukushintsha amashaneli e-analog (amashaneli edijithali azokweqiwa ngokuzenzakalelayo) njengaku-TV. Kuphela esikhundleni sokukhangisa nezindaba sizobona into efana nale:
Kuyo singabona amapharamitha ayinhloko wesignali: leli izinga ku-dBµV kanye nesilinganiso sezinga lesignali emsindweni (noma kunalokho, umthwali/umsindo). Njengoba iziteshi kumafrikhwensi ahlukene zingaphansi kwezimo ezihlukene ngesikhathi sokudlulisela, kuyadingeka ukuthatha izilinganiso kumashaneli amaningana (okungenani emaqinisweni amabili ebangeni lefrikhwensi).
Ngokuhambisana nezidingo ze-GOST, izinga lesiginali kokokufaka kumamukeli kufanele libe kububanzi obusuka ku-60 kuye ku-80 dB. Ukuze uqinisekise lawa manani, umhlinzeki kufanele anikeze obhalisile endaweni yokuxhuma (imvamisa iphaneli yamanje ephansi ekufikeni) ngokufanelekile 70-75 dB. Iqiniso liwukuthi noma yini ingenzeka emagcekeni obhalisile: ikhebula lekhwalithi eliphansi noma elimele, abahlukanisi abakhethiwe ngokungalungile, i-TV enomkhawulo ompofu wokuzwela. Konke lokhu ekugcineni kuzoholela ekunciphiseni isignali. Kodwa izinga lesiginali eliphezulu kakhulu nalo libi: i-TV enhle enomjikelezo ofanele, okuhlanganisa i-AGC yekhwalithi ephezulu, ingacubungula ngokuphephile isiginali engaphezu kuka-100 dB, kodwa ama-TV amaningi angabizi awakwazi nje ukumelana nesiginali enjalo.
Umngane obalulekile wanoma iyiphi isignali umsindo. Yethulwa ngemishini esebenzayo esigabeni sokwakheka kwesignali, bese ama-amplifiers ekhulisa kanye nesiginali, futhi aze engeze okuncane okwazo. Ngesiginali ye-analog, lokhu kubaluleke kakhulu: lonke lelo qhwa, imivimbo nokunye ukuhlanekezela kuwumsindo odinga ukulinganiswa futhi, vele, kungcono unciphise. Ukuhlola ikhwalithi yesiginali ye-analog, isilinganiso sesiginali ewusizo emsindweni siyasetshenziswa, okungukuthi, ukuphakama kwenani, kungcono. I-GOST ichaza inani eliphansi njenge-43 dB; empeleni, obhalisile uthola, yebo, okuningi, kodwa ngenxa yezizathu ezifanayo nokuncishiswa, le pharamitha ingaba yimbi kakhulu endleleni ukusuka kuphaneli ukuya ku-TV. Nakuba kukholakala ukuthi izintambo ezingenzi lutho azikwazi ukwethula umsindo, zingathola ukuphazamiseka kukhebuli kagesi eseduze, isibonelo, noma ithole isignali enamandla yasemhlabeni evela kophindayo. Ngaphezu kwalokho, abahlukanisi abasezingeni eliphansi noma asebekhulile bangenza umsebenzi wabo - lokhu kufanelekile ukunaka.
Empeleni, ikhwalithi yesithombe sokugcina incike kakhulu kumabonakude uqobo. Yiqiniso, isignali ye-analog ayinayo i-redundancy yokuvikela umsindo, kodwa izihlungi zakwamukeli ezisezingeni eliphezulu, kanye nama-amplifiers akhelwe ngaphakathi, zingasebenza izimangaliso, kodwa umhlinzeki, vele, akufanele athembele kulokhu.
Source: www.habr.com