Esephepheni of ulwazi lwesandi

Nayiphi na inkqubo ndingekawuboni ukuguqulwa zibe uhlobo yedijithali. Ngenxa yoko, encoding ulwazi audio nge iikhompyutha yenziwa ngolu hlobo lulandelayo:

- intlokoma air kumekaka izixhobo ezibuthathaka;

- yabulawa Ukuguqulwa ibe umsinga wombane, apho kangaphi (awo) iyahluka ngokufanelekileyo;

- the current engumphumela zavavanywa, ngamanye kukho isampulu wayo (ngamanye amaxesha sithi okubekwa encoding ulwazi yokubini audio).

Oku kubangela analog electronic flow audio sokuqala ngcono, kungona amaza iisampuli kwi isampulu kunye nobunzulu ikhowudi.

Ngamanye amazwi, encoding kolwazi odiyo - yinkqubo aziqhelileyo ukuguqula uphawu ezininzi analog ibe digital, eyenzelwe ukuba kuqhutywe kwisixhobo efanelekileyo. Makhe sihlolisise amanyathelo kunye neendlela zokusebenzisa idijithali yesandi.

Discretization ixesha yesakhelo - sisiseko idijithali. Ngokutsho Kotel'nikova theorem, lo uphawu lukagesi analogu kungenziwa idijithali ngokufunda inyathelo elithile kuthotho eliqhubekekayo amaxabiso awo yayo. Nezihlandlo ifundeke kufuneka ubuncinane kabini rhoqo kugcwala uphawu engundoqo. Ukuba kuyimfuneko, idijithali Togu "ikhowudi yemvelaphi" eziya kwi-frequency yokusebenza 0-20 kHz yesampulu kufuneka wenziwe ungabi ngaphantsi kwe-40 amawaka. Times yesibini (40 kHz) nganye. Komculo kubhekisela kwinani ngokwemilinganiso nganye yesibini umthombo analog uphawu (isampulu, amaza isampuli). Ngenxa yokwanda isampuli ukunyuka kungekuphela umgangatho kodwa ke umthamo onesiphumo umsinga data.

Kwakhona, audio ulwazi ikhowudi ingaqhutywa nangezinye iindlela. Njengoko, umzekelo, idijithali quantizer nonuniform, maxa wambi ebizwa lwe logarithm olusezantsi. Xa usebenzisa lonke uluhlu awo kwemiqathango yahlulwe yangamacandelo kunye amaxabiso aphezulu nezisezantsi. encoding iinkcukacha ezithe vetshe audio kwenzeka ngokusebenzisa izixa ezikhulu amanqanaba quantization kwiindawo ezinexabiso awo encinane (and vice versa). Qaphela, noba kunjani, ukuba inani elipheleleyo kumanqanaba kuhlala efanayo indlela quantization uniform (PCM).

Indlela ezahlukileyo ngokupheleleyo luqhutywa enye indlela khowudi. Ibizwa ngokuba "Pulse umehluko Code kwezwi» (DPCM). Ekubeni kukho indlela akwenziwanga phantsi quantization le awo yomqondiso ngqo kunye nexabiso layo isihlobo. Ngenxa yoko kunokwenzeka ukufikelela kunciphiso umthamo awayephantsi data, ekubeni indlela ezisebenza uqikelelo elandelayo zeesampulu umqondiso yokuqala.

Ulwazi ukhowudo processing audio ezichazwe kweli phepha kufuna esenza uguqulelo "analog-to-digital". Le nkqubo ngokusebenzisa i ADC (analog-to-digital lokuguqulela). Kunye nalo msebenzi, isixhobo ngasinye elijonge umnini ngemihla ikhompyutha exhotyiswe ikhadi lesandi (kule meko kukho inkqubo reverse - ofumana uphawu analog ukususela kumsinga digital).

Imisebenzi ADC zimi ngolu hlobo lulandelayo:

- limited frequency bandwidth. Ukusebenzisa amacebo okucoca, amacandelo umqondiso baya kunqunyulwa, nezihlandlo apho - ngaphezu kwesiqingatha rhoqo isampuli (isizathu ezichazwe ngaphambili).

- Ukukhetha amaxabiso awo rhoqo. Oku kubangela uphawu analog nto imelwe ngolandelelwano ziikhowudi omnye ngegalelo lazo (discretization).

- Umhlobo Replacement efunyenwe iyasebenza ungazama ukunciphisa amaxabiso zabo ikufutshane ukusuka kuluhlu ezinzileyo (quantization).

- Guqula ixabiso ngalinye quantized yenani olunemiqathango kwamanqanaba quantization (ixabiso ngalinye - serial number). Eli nqanaba yokugqibela yedijithi.