I-MER: Isilinganiso sephutha lokuguquguquka, okuyisilinganiso senani elisebenzayo lobukhulu be-vector nenani elisebenzayo lobukhulu bephutha kumdwebo we-constellation (isilinganiso sesikwele sobukhulu be-vector obufanele nesikwele sobukhulu be-vector yephutha). Kungenye yezinkomba eziyinhloko zokulinganisa ikhwalithi yezibonakaliso ze-TV zedijithali. Kubaluleke kakhulu emiphumeleni yokulinganisa i-logarithmic yokuphambuka okubekwe phezu kwesignali ye-digital modulation. Kufana nesilinganiso sesignali-kuya-kumsindo noma isilinganiso se-carrier-kuya-kumsindo esisetshenziswa ohlelweni lwe-analog. Luhlelo lokwahlulela Ingxenye ebalulekile yokubekezelela ukwehluleka. Ezinye izinkomba ezifanayo njengesilinganiso sephutha le-BER bit, isilinganiso se-carrier-kuya-kumsindo se-C/N, amandla aphakathi kwezinga lamandla, umdwebo we-constellation, njll.
Inani le-MER livezwa ku-dB, futhi uma inani le-MER likhulu, ikhwalithi yesignali iba ngcono. Uma isignali ingcono, izimpawu ezilungisiwe zisondela kakhulu endaweni efanele, futhi okuphambene nalokho. Umphumela wokuhlolwa kwe-MER ubonisa ikhono lesamukeli sedijithali lokubuyisela inombolo ye-binary, futhi kukhona isilinganiso sesignali-kuya-kumsindo esiqondile (S/N) esifana nesesignali ye-baseband. Isignali eguquliwe ye-QAM iphuma kusukela ekugcineni kwangaphambili futhi ingena ekhaya ngenethiwekhi yokufinyelela. Isibonakaliso se-MER sizowohloka kancane kancane. Endabeni yomdwebo wezinkanyezi 64QAM, inani lomkhawulo we-empirical we-MER lingu-23.5dB, kanti ku-256QAM lingu-28.5dB (umphumela wangaphambili kufanele ube Uma uphakeme kune-34dB, ungaqinisekisa ukuthi isignali ingena ekhaya ngokujwayelekile, kodwa ayikuvimbeli ukungalingani okubangelwa ikhwalithi yekhebula lokudlulisa noma ukuphela okungaphansi). Uma uphansi kunaleli nani, umdwebo wezinkanyezi ngeke uvalwe. Izidingo zokukhipha ukuguquguquka kwesikhombisi se-MER front-end: Ku-64/256QAM, i-front-end > 38dB, i-sub-front-end > 36dB, i-optical node > 34dB, i-amplifier > 34dB (eyesibili ingu-33dB), i-user end > 31dB (eyesibili ingu-33dB), ngaphezu kuka-5 Iphuzu elibalulekile le-MER livame ukusetshenziswa ukuthola izinkinga zomugqa we-TV yekhebula.
Ukubaluleka kwe-MER MER kubhekwa njengohlobo lokulinganisa i-SNR, futhi incazelo ye-MER yile:
①. Kuhlanganisa izinhlobo ezahlukene zomonakalo esignalini: umsindo, ukuvuza komthwali, ukungalingani kwe-IQ amplitude, kanye nomsindo wesigaba.
②. Ibonisa ikhono lemisebenzi yedijithali lokubuyisela izinombolo ezimbili; ikhombisa izinga lomonakalo kumasignali e-TV yedijithali ngemva kokudluliswa ngenethiwekhi.
③. I-SNR iyipharamitha yebhendi yesisekelo, kanti i-MER iyipharamitha yemvamisa yomsakazo.
Uma ikhwalithi yesignali yehla iye ezingeni elithile, izimpawu zizogcina zibhalwe ngendlela engafanele. Ngalesi sikhathi, izinga langempela lephutha le-bit i-BER liyakhula. I-BER (Izinga Lephutha Le-Bit): Izinga lephutha le-Bit, elichazwa njengesilinganiso senani lama-bit ephutha nenani eliphelele lama-bit. Kumasignali edijithali e-binary, njengoba ama-bit e-binary edluliselwa, izinga lephutha le-bit libizwa ngokuthi izinga lephutha le-bit (BER).
I-BER = Iphutha Lesilinganiso Sebhithi/Inani Lebhithi Eliphelele.
I-BER ngokuvamile ivezwa ngenothi yesayensi, kanti uma i-BER iphansi, kuba ngcono. Uma ikhwalithi yesignali ilungile kakhulu, amanani e-BER ngaphambi nangemuva kokulungiswa kwephutha afana; kodwa esimweni sokuphazamiseka okuthile, amanani e-BER ngaphambi nangemuva kokulungiswa kwephutha ahlukile, futhi ngemva kokulungiswa kwephutha Izinga lephutha le-bit liphansi. Uma iphutha le-bit lingu-2 × 10-4, i-mosaic engaphelele ivela ngezikhathi ezithile, kodwa isengabukwa; i-BER ebalulekile ingu-1 × 10-4, kuvela inani elikhulu le-mosaics, futhi ukudlala kwesithombe kubonakala ngezikhathi ezithile; i-BER enkulu kuno-1 × 10-3 ayikwazi ukubukwa nhlobo. bukela. Inkomba ye-BER inenani lokubhekisela kuphela futhi ayibonisi ngokugcwele isimo semishini yonke yenethiwekhi. Ngezinye izikhathi ibangelwa ukwanda okungazelelwe ngenxa yokuphazamiseka okusheshayo, kuyilapho i-MER iphambene ngokuphelele. Yonke inqubo ingasetshenziswa njengokuhlaziywa kwephutha ledatha. Ngakho-ke, i-MER inganikeza isexwayiso sangaphambi kwesikhathi sezimpawu. Lapho ikhwalithi yesignali yehla, i-MER izoncipha. Ngokwanda komsindo nokuphazamiseka ngezinga elithile, i-MER izoncipha kancane kancane, kuyilapho i-BER ingashintshi. Kuphela uma ukuphazamiseka kwanda ngezinga elithile, i-MER. I-BER iqala ukuwohloka lapho i-MER yehla njalo. Lapho i-MER yehla ezingeni lomkhawulo, i-BER izokwehla kakhulu.
Isikhathi sokuthunyelwe: Feb-23-2023