Inkqubela phambili ihambela phambili kwiplanethi yonke, kodwa, ngelishwa, ayikhawulezi ngokukhawuleza njengoko besingathanda. Ngoko ke, okwangoku, izigidi zethelevishini azikwazi ukufumana isignali yedijithali ngaphandle kweentonga, kwaye umnikezeli okhathalelayo malunga nokuxhamla kombhalisi kufuneka anike uphawu lweTV, kubandakanywa nefom ye-analog.
Iziqulatho zoluhlu lwamanqaku
- Icandelo 3: Icandelo leSiginali ye-Analog
- Icandelo 4: ICandelo loMqondiso weDijithali
- Icandelo 5: Inethiwekhi yokusabalalisa i-coaxial
- Icandelo 6: I-RF Signal Amplifiers
- Icandelo 7: Abamkeli bamehlo
- Icandelo 8: Inethiwekhi ye-Optical backbone
- Icandelo 9: Intloko
- Icandelo 10: Ukulungisa inethiwekhi yeCATV
Isicwangciso sikarhulumente sokucima usasazo lwe-analogu lwamajelo e-TV
Nangona oku kungahambelani ngokupheleleyo nesihloko, akunakwenzeka ukuba ungawuhoyi umba otshisayo ngoku.
Ngoko ke: zonke ezi ncoko zinxulumene nosasazo kuphela. Oko kukuthi, umqondiso ohamba emoyeni ukusuka kwinqaba yeTV ekufutshane. Kuphela ngumbuso ojongene nalo mqondiso eRashiya, kwaye ezimbini kuphela (kweminye imimandla emithathu) i-multiplexes iya kuhlala kuyo. Icandelo le-analog yosasazo lwentambo ixhomekeke kuphela kubaboneleli kwaye kusenokwenzeka ukuba ayizukuhamba. Ke ukuba iTV yakho ayiqhagamshelwanga kwi-eriyali ebekwe eluphahleni lwendlu okanye kwifestile yefestile, oku kucinywa ngokuqinisekileyo akuyi kukuchaphazela. Kutheni ndisithi “phantse” kwaye “kunokwenzeka kakhulu”? Inyani kukuba abanye abaqhubi bekhebula sele bebhengeze ukupheliswa okuzayo kokubonelela ngeempawu ze-analog kubabhalisi. Kunzima ukuqonda inkuthazo, kuba njengoko kucacile kwiCandelo loku-1 lamanqaku am, oku akunako ukuzisa ukonga okubalulekileyo kwisixhobo: ngamakhadi ambalwa okwandisa kwi-chassis eqhelekileyo anoxanduva loku. Ukukhulula ii-frequency zabathwali kukwayinkuthazo ethandabuzekayo: akukho mfuneko kwimarike yenani elinjalo lamatshaneli edijithali anokufakwa endaweni ye-analogue ekhubazekileyo. Indlela yodwa yokwenza imali apha kukuthengisa iibhokisi ezibekwe phezulu kubabhalisi, kodwa siya kukushiya oko kwisazela sabaqhubi.
Iiparamitha zeSiginali ye-Analog
Isiginali ye-analog kamabonwakude sisimbuku semiqondiso emithathu: iamplitude emodareyithiweyo ukuqaqamba kunye nombala, kunye nesandi esimodyuliweyo. Kodwa ukuvavanya ubuninzi kunye nomgangatho, kwanele ukuthatha lo mqondiso njengento enye, nangona sonke siye saqaphela ngaphezu kweyodwa ukuba nangomfanekiso ombi, isandi esivela kwiTV silungile. Oku kungenxa yokhuselo olungcono lwe-FM. Ukulinganisa iiparamitha zesignali ye-analog, isixhobo se-Deviser DS2400T sibonelela ngale ndlela ilandelayo:
Kule modi, ungasebenzisa amaqhosha ukutshintsha itshaneli ze-analog (iitshaneli zedijithali ziya kutsitywa ngokuzenzekelayo) njengeTV. Kuphela endaweni yentengiso kunye neendaba siya kubona into enje:
Kuyo sinokubona iiparamitha eziphambili zomqondiso: eli linqanaba kwi-dBµV kunye nomlinganiselo wezinga lomqondiso kwingxolo (okanye kunoko, umthwali / ingxolo). Ekubeni amajelo kwiifrikhwensi ezahlukeneyo axhomekeke kwiziganeko ezahlukeneyo ngexesha losulelo, kuyafuneka ukuba kuthathwe imilinganiselo kwiitshaneli ezininzi (ubuncinci kubini obugqithisileyo kuluhlu lwamaza).
Ngokuhambelana neemfuno ze-GOST, inqanaba lesignali kwigalelo kummkeli kufuneka libe kuluhlu ukusuka kwi-60 ukuya kwi-80 dB. Ukuze kuqinisekiswe la maxabiso, umboneleli kufuneka anike umrhumi kwindawo yokudibanisa (ngokuqhelekileyo iphaneli ephantsi-yangoku ekufikeni) ngokufanelekileyo i-70-75 dB. Inyani kukuba nantoni na inokwenzeka kwindawo yombhalisi: ikhebula elikumgangatho ophantsi okanye eyonakalisiweyo, abahluli abakhethiweyo ngokungalunganga, iTV enomda wokuva ubunzima. Konke oku ekugqibeleni kuya kukhokelela ekunciphiseni umqondiso. Kodwa inqanaba lophawu oluphezulu kakhulu nalo libi: iTV elungileyo enesekhethi echanekileyo, kubandakanya i-AGC ekumgangatho ophezulu, inokuqhuba ngokukhuselekileyo umqondiso ongaphezulu kwe-100 dB, kodwa uninzi lweeTV ezingabizi kakhulu azinakumelana nomqondiso onjalo.
Iqabane eliyimfuneko kuwo nawuphi na umqondiso yingxolo. Yaziswa ngezixhobo ezisebenzayo kwinqanaba lokwenziwa komqondiso, emva koko ii-amplifiers ziyayikhulisa kunye nomqondiso, kwaye zidibanise nentwana yazo. Kwisiginali ye-analog, oku kubaluleke kakhulu: lonke elo khephu, imivimbo kunye nezinye iziphazamiso ziyingxolo efuna ukulinganiswa kwaye, ngokuqinisekileyo, iyancitshiswa. Ukuvavanya umgangatho wesignali ye-analog, umlinganiselo wesignali eluncedo kwingxolo isetyenziswa, oko kukuthi, ixabiso eliphezulu, lingcono. I-GOST ichaza ixabiso eliphantsi njenge-43 dB; Enyanisweni, umrhumi ufumana, ngokuqinisekileyo, ngaphezulu, kodwa ngenxa yezizathu ezifanayo njenge-attenuation, le parameter ingaba mbi kakhulu endleleni ukusuka kwiphaneli ukuya kwiTV. Nangona kukholelwa ukuba i-wiring ye-passive ayikwazi ukuzisa ingxolo, inokufumana ukuphazamiseka kwintambo yombane ekufutshane, umzekelo, okanye ifumane umqondiso onamandla we-terrestrial ovela kumntu ophindayo. Ukongeza, abahluli abakumgangatho ophantsi okanye abadala banokwenza umsebenzi wabo - oku kukufanelekile ukunikela ingqalelo.
Enyanisweni, umgangatho wokugqibela womfanekiso uxhomekeke kumlinganiselo omkhulu kwiTV ngokwayo. Ngokuqinisekileyo, isignali ye-analog ayinayo i-redundancy yokukhusela ingxolo, kodwa izihlungi kwi-high-quality receivers, kunye ne-amplifiers eyakhelwe ngaphakathi, inokusebenza ngokumangalisayo, kodwa umboneleli, ngokuqinisekileyo, akafanele athembele kule nto.
umthombo: www.habr.com