MER: Umlinganiselo wemposiso yokumodareyitha, umlinganiselo wexabiso elisebenzayo lobungakanani bevekhtha ukuya kwixabiso elisebenzayo lempazamo yobukhulu kwidayagram yeqela leenkwenkwezi (umyinge wesikwere sobukhulu bevektha obufanelekileyo kwisikwere sobukhulu bevektha yempazamo) . Sesinye sezalathisi eziphambili zokulinganisa umgangatho wemiqondiso yedijithali yeTV. Ibaluleke kakhulu kwiziphumo zomlinganiselo welogarithmic wokugqwethwa okubekwe ngaphezulu kumqondiso womodareyitha wedijithali. Ifana ne-signal-to-noise ratio okanye i-carrier-to-noise ratio esetyenziswe kwinkqubo ye-analog. Yinkqubo yokugweba Inxalenye ebalulekileyo yokusilela ukunyamezela. Ezinye izalathi ezifanayo ezifana ne-BER bit error rate, i-C/N carrier-to-noise ratio, i-power level average power level, i-constellation diagram, njl.
Ixabiso le-MER libonakaliswe kwi-dB, kwaye ixabiso elikhulu le-MER, ngcono umgangatho wesignali. Okukhona umqondiso ungcono, kokukhona iisimboli ezimodulisiweyo zisondele kakhulu kwindawo efanelekileyo, kwaye ngokuphambeneyo. Isiphumo sovavanyo lwe-MER sibonisa amandla omamkeli wedijithali ukubuyisela inombolo yebhinari, kwaye kukho injongo ye-signal-to-noise ratio (S / N) efana neyomqondiso we-baseband. I-QAM-modulated signal iphuma kwi-front end kwaye ingena ekhaya ngokusebenzisa inethiwekhi yokufikelela. Isalathisi se-MER siya kuhla kancinci kancinci. Kwimeko ye-constellation diagram 64QAM, ixabiso lomda we-MER yi-23.5dB, kwaye kwi-256QAM yi-28.5dB (isiphumo sangaphambili kufuneka sibe Ukuba siphezulu kune-34dB, inokuqinisekisa ukuba isignali ingena ekhaya ngokuqhelekileyo. , kodwa ayikhupheli ngaphandle kokungaqhelekanga okubangelwa umgangatho wentambo yokuhambisa okanye i-sub-front end). Ukuba ingaphantsi kweli xabiso, umzobo weenkwenkwezi awuyi kutshixwa. Isalathisi se-MER Iimfuno zesiphumo sokumodareyitha isiphelo sesiphelo sangaphambili: Kwi-64/256QAM, isiphelo sangaphambili> 38dB, isiphelo esisezantsi> 36dB, i-optical node> 34dB, iamplifier> 34dB (yesibini yi-33dB), isiphelo somsebenzisi> 31dB (yesibini yi33dB ), ngaphezulu kwe-5 Indawo engundoqo ye-MER ikwasetyenziswa rhoqo ukufumana iingxaki zentambo ye-TV.
Ukubaluleka kwe-MER MER kuthathwa njengohlobo lomlinganiselo we-SNR, kwaye intsingiselo ye-MER ithi:
①. Ibandakanya iintlobo ezahlukeneyo zomonakalo kwisignali: ingxolo, ukuvuza komthwali, ukungalingani kwe-IQ amplitude, kunye nomsindo wesigaba.
②. Ibonisa amandla emisebenzi yedijithali ukubuyisela amanani okubini; ibonakalisa iqondo lomonakalo kwiisignali zedijithali zeTV emva kokusasazwa kuthungelwano.
③. I-SNR yiparameter ye-baseband, kwaye i-MER yiparamitha yamaza kanomathotholo.
Xa umgangatho wesignali wehla ukuya kwinqanaba elithile, iisimboli ziya kugqitywa ngokungalunganga. Ngeli xesha, elona nqanaba lempazamo encinci BER liyenyuka. I-BER (I-Bit Error Rate): Izinga lempazamo yeBit, lichazwa njengomlinganiselo wenani leempazamo zebits ukuya kwitotali yenani leebits. Kwimiqondiso yokubini yedijithali, njengoko amasuntswana okubini ehanjiswa, izinga lempazamo encinci libizwa ngokuba yi-bit error rate (BER).
I-BER = i-Error Bit Rate / i-Bit Rate.
I-BER ngokuqhelekileyo ibonakaliswe kwi-notation yesayensi, kwaye i-BER ephantsi, ingcono. Xa umgangatho wesignali ulungile kakhulu, ixabiso le-BER ngaphambi nangemva kokulungiswa kwephutha liyafana; kodwa kwimeko yokuphazamiseka okuthile, amaxabiso e-BER ngaphambi nasemva kokulungiswa kwempazamo ahlukile, kwaye emva kokulungiswa kwempazamo Isantya sempazamo encinci sisezantsi. Xa impazamo encinci ingu-2 × 10-4, imosaic engaphelelanga ivela ngamaxesha athile, kodwa isenokujongwa; i-BER ebalulekileyo yi-1 × 10-4, inani elikhulu le-mosaics livela, kunye nokudlala komfanekiso kubonakala kuphakathi; I-BER enkulu kuno-1×10-3 ayinakujongwa kwaphela. jonga. Isalathisi se-BER sixabiso lereferensi kuphela kwaye ayibonakalisi ngokupheleleyo imeko yezixhobo zenethiwekhi yonke. Ngamanye amaxesha kubangelwa kuphela ukwanda ngokukhawuleza ngenxa yokuphazamiseka ngokukhawuleza, ngelixa i-MER ichasene ngokupheleleyo. Yonke inkqubo ingasetyenziswa njengohlalutyo lwempazamo yedatha. Ke ngoko, i-MER inokubonelela ngesilumkiso kwangethuba kwimiqondiso. Xa umgangatho wesignali uyancipha, i-MER iya kuncipha. Ngokunyuka kwengxolo kunye nokuphazamiseka kwinqanaba elithile, i-MER iya kuncipha ngokuthe ngcembe, ngelixa i-BER ihlala ingatshintshi. Kuphela xa uphazamiseko lunyuka ukuya kumlinganiselo othile, i-MER I-BER iqala ukuwohloka xa i-MER ihla ngokuqhubekayo. Xa i-MER yehla kwinqanaba lomgca, i-BER iya kuhla ngokukhawuleza.
Ixesha lokuposa: Feb-23-2023