DAB vs DAB+
DAB stands rau Digital Audio Broadcast, ib lub tshuab tsim nyob rau hauv 1980's raws li kev daws teeb meem rau cov bandwidth sab hauv FM thiab AM zaus ntau. AM thiab FM, uas yog analog txoj kev tshaj tawm, yog hloov los ntawm digital broadcasting method DAB thiab nws cov qauv tshiab tshaj tawm nyob rau hauv 2006. Lub teb chaws thoob plaws ntiaj teb siv DAB broadcasting systems; Qhov tseem ceeb tshaj, nyob hauv Europe.
More about DAB
DAB ua haujlwm ntawm kev sib txuas ob lub thev naus laus zis digital. MUSICAM, uas yog lub kaw lus compression, txo qhov loj ntawm cov ntaub ntawv digital kom xa mus, thiab COFDM (Coded Orthogonal Frequency Division Multiplex) ua rau kev sib kis tau muaj zog thiab tau txais cov cim kev ntseeg siab.
Txoj kev compression tso siab rau tshem tawm cov suab tsis hnov tsw thiab zaus rau tib neeg pob ntseg. Piv txwv li, cov suab tom qab uas dhau los ntawm cov suab nrov tseem ceeb yog tsis saib xyuas hauv cov txheej txheem compression, ua rau cov ntaub ntawv xa mus tau zoo npaum li cas qis dua. Nyob rau hauv txoj kev COFDM, lub teeb liab tau muab faib thoob plaws 1, 536 tus neeg nqa khoom sib txawv, thiab tseem nyob rau lub sijhawm. Cov txheej txheem no tso cai rau tus txais yuav rov tsim kho qhov qub teeb liab, txawm tias qee qhov kev cuam tshuam. Yog li ntawd, theoretically DAB tuaj yeem siv rau hauv ib puag ncig muaj kev cuam tshuam uas ua rau muaj kev txais tos tsis zoo.
Qhov cuam tshuam cuam tshuam tau pom hauv FM thev naus laus zis, vim muaj ntau txoj hauv kev coj los ntawm cov teeb liab, raug zam los ntawm DAB. Raws li qhov tshwm sim, thaj chaw loj dua tuaj yeem them nrog ib zaus, tsis yog npog thaj chaw nrog ntau zaus los tiv thaiv kev cuam tshuam.
A DAB multiplex siv 2, 300, 000 'ntsis' rau kev sib kis. Kwv yees li ib nrab ntawm lub ntim yog siv rau cov kev pabcuam suab thiab cov ntaub ntawv, thaum muaj lub ntim rau kev tiv thaiv kev sib kis tsis raug. Txhua multiplex muaj peev xwm nqa tau ib qho kev sib xyaw ntawm mono thiab stereo tshaj tawm, thiab cov ntaub ntawv kev pabcuam, thiab tus naj npawb ntawm txhua tus nyob ntawm qhov xav tau zoo. Cov kev pabcuam tuaj yeem hloov pauv txhua hnub raws li lub sijhawm ua haujlwm.
Qhov zoo ntawm DAB tshaj lwm txoj kev sib kis yog kev txhim kho hauv kev txais tos zoo thiab lub suab zoo, qhov sib txawv bandwidths, thiab tus nqi qis ntawm kev sib kis. Rau cov neeg siv, ntxiv nta xws li Dynamic Label Segment (xov tooj cua ntawv nyeem) tuaj yeem muab. Nrog DAB, ntau txoj kev tuaj yeem kis tau vim tias txo qis kev sib tham thiab cuam tshuam ua rau rov siv dua bandwidth tsawg dua thiab faib cov zaus ntau dua. Qee cov khoom siv DAB kuj txhawb nqa xov tooj cua hauv internet.
Txawm hais tias qhov zoo DAB ua rau muaj kev nyuaj rau cov neeg txais, vim qhov tsis zoo ntawm kev kho qhov yuam kev siv hauv kev sib kis. Cov tshaj tawm txo qis qhov bandwidth ntawm ib channel kom nce tus naj npawb ntawm cov channel hauv cov khoom siv zaus, ua rau poob qhov zoo.
More about DAB+
Hauv xyoo 2006, DBM txoj cai tswj hwm DAB cov qauv qhia cov qauv tshiab rau DAB kis. Cov suab CODEC tshiab dua thiab muaj zog dua kev ua yuam kev kho coding tau txais yuav.
DAB cov khoom siv tsis raug xa mus; uas yog, DAB ntaus ntawv tsis tuaj yeem tau txais DAB + cov cim. Kev hloov kho firmware yuav tsum tau ntxiv los ua kom lub cuab yeej tau txais DAB + cov cim.
DAB vs DAB+
• DAB+ is the upgraded standard of the DAB.
• DAB siv MPEG-1 Audio Layer 2 audio CODEC, hos DAB + siv HE-AAC v2 audio CODEC (tseem hu ua eAAC+) thiab MPEG Surround audio format.
• DAB siv punctured convolutional coding rau nws ECC, hos DAB + siv Reed-Solomon coding, uas yog ib tug muaj zog yuam kev kho coding.
• As result, DAB+ has
– Lub suab zoo dua
– txais tos zoo dua
• DAB transmissions is not compatible with new DAB+ devices.