I-MER: Umlinganiselo wempazamo yemodulation, ongumlinganiselo wexabiso elisebenzayo lobukhulu bevektha ukuya kwixabiso elisebenzayo lobukhulu bempazamo kwidayagramu ye-constellation (umlinganiselo wesikwere sobukhulu bevektha efanelekileyo ukuya kwisikwere sobukhulu bevektha yempazamo). Yenye yezalathisi eziphambili zokulinganisa umgangatho weempawu zeTV yedijithali. Ibaluleke kakhulu kwiziphumo zokulinganisa i-logarithmic zokuphazamiseka okubekwe kwisignali yemodulation yedijithali. Ifana nomlinganiselo wesignali-kwingxolo okanye umlinganiselo we-carrier-kwingxolo osetyenziswa kwinkqubo ye-analog. Yinkqubo yokugweba Inxalenye ebalulekileyo yokunyamezelana nokusilela. Ezinye izalathisi ezifanayo ezifana ne-BER bit error rate, umlinganiselo we-C/N carrier-to-noise, amandla aphakathi enqanaba lamandla, umzobo we-constellation, njl.
Ixabiso le-MER lichazwa kwi-dB, kwaye ixabiso le-MER likhulu, kokukhona umgangatho wesignali ungcono. Okukhona isignali ingcono, kokukhona iimpawu ezilungisiweyo zisondela kwindawo efanelekileyo, kwaye ngokuchaseneyo. Isiphumo sovavanyo se-MER sibonisa amandla omamkeli wedijithali okubuyisela inani le-binary, kwaye kukho umlinganiselo wesignali-kwingxolo (S/N) ofana nowesignali ye-baseband. Isignali eguquliweyo ye-QAM iphuma kwisiphelo esingaphambili kwaye ingena ekhaya ngenethiwekhi yokufikelela. Isalathisi se-MER siya kuhla kancinci kancinci. Kwimeko yedayagramu ye-constellation 64QAM, ixabiso lomgca we-empirical we-MER yi-23.5dB, kwaye kwi-256QAM yi-28.5dB (isiphumo sangaphambili kufuneka sibe. Ukuba iphezulu kune-34dB, inokuqinisekisa ukuba isignali ingena ekhaya ngokwesiqhelo, kodwa ayikuthinteli ukungaqhelekanga okubangelwa ngumgangatho wentambo yokudlulisa okanye isiphelo esingaphantsi). Ukuba iphantsi kweli xabiso, idayagramu ye-constellation ayiyi kutshixwa. Iimfuno zesiphumo se-MER indicator front-end modulation output: Kwi-64/256QAM, i-front-end > 38dB, i-sub-front-end > 36dB, i-optical node > 34dB, i-amplifier > 34dB (eyesibini yi-33dB), i-user end > 31dB (eyesibini yi-33dB), ngaphezulu kwe-5 Ingongoma ephambili ye-MER ikwasetyenziswa rhoqo ukufumana iingxaki ze-cable TV line.
Ukubaluleka kwe-MER MER kuthathwa njengohlobo lomlinganiselo we-SNR, kwaye intsingiselo ye-MER yile:
2. Ibandakanya iintlobo ezahlukeneyo zomonakalo kwisignali: ingxolo, ukuvuza komthwali, ukungalingani kwe-IQ amplitude, kunye nengxolo yesigaba.
2. Ibonisa amandla emisebenzi yedijithali okubuyisela amanani e-binary; ibonisa ubungakanani bomonakalo kwiisignali zeTV zedijithali emva kokuba zidluliselwe ngenethiwekhi.
③. I-SNR yiparameter ye-baseband, kwaye i-MER yiparameter ye-radio frequency.
Xa umgangatho wesignali uhla uye kwinqanaba elithile, iimpawu ekugqibeleni ziya kuchazwa ngokuchanekileyo. Ngeli xesha, izinga lempazamo yebhithi yokwenyani i-BER iyanda. I-BER (Izinga leMpazamo yeBhithi): Izinga lempazamo yebhithi, elichazwa njengomlinganiselo wenani leebhithi zempazamo kwinani lilonke leebhithi. Kwiisignali zedijithali zebhithi, ekubeni iibhithi zebhithi zidluliselwa, izinga lempazamo yebhithi libizwa ngokuba yizinga lempazamo yebhithi (i-BER).
I-BER = Ixabiso leBit yeMpazamo/Ixabiso leBit iyonke.
I-BER ngokubanzi ichazwa ngokwesayensi, kwaye okukhona i-BER iphantsi, kokukhona ingcono. Xa umgangatho wesignali ulungile kakhulu, amaxabiso e-BER ngaphambi nasemva kokulungiswa kwempazamo afana; kodwa kwimeko yokuphazamiseka okuthile, amaxabiso e-BER ngaphambi nasemva kokulungiswa kwempazamo ahlukile, kwaye emva kokulungiswa kwempazamo Izinga lempazamo ye-bit liphantsi. Xa impazamo ye-bit ingu-2×10-4, i-mosaic engaphelelanga ibonakala ngamanye amaxesha, kodwa isenokujongwa; i-BER ebalulekileyo yi-1×10-4, inani elikhulu le-mosaics livela, kwaye ukudlala komfanekiso kubonakala kungenzeki; i-BER engaphezulu kwe-1×10-3 ayinakujongwa konke konke. jonga. Isalathisi se-BER sixabiso lesalathiso kuphela kwaye asibonisi ngokupheleleyo imeko yesixhobo senethiwekhi yonke. Ngamanye amaxesha sibangelwa kuphela kukunyuka ngequbuliso ngenxa yokuphazamiseka kwangoko, ngelixa i-MER ichasene ngokupheleleyo. Yonke inkqubo ingasetyenziswa njengohlalutyo lweempazamo zedatha. Ke ngoko, i-MER inokubonelela ngesilumkiso kwangethuba kwiisignali. Xa umgangatho wesignali uncipha, i-MER iya kuncipha. Ngokwanda kwengxolo nokuphazamiseka kwinqanaba elithile, i-MER iya kuncipha kancinci, ngelixa i-BER ingatshintshi. Kuphela xa ukuphazamiseka kusanda ukuya kwinqanaba elithile, i-MER. I-BER iqala ukonakala xa i-MER ihla ngokuqhubekayo. Xa i-MER ihla iye kwinqanaba elisezantsi, i-BER iya kwehla ngokukhawuleza.
Ixesha lokuthumela: Februwari-23-2023