Coding kolwazi alalelwayo

Noma yimuphi inqubo empeleni zibe ifomu digital. Ngakho, lokufaka ikhodi kolwazi umsindo nge-computer Kwenziwa kanje:

- emoyeni kunyakaza eqoshiwe amadivayisi ebucayi;

- ababulawa ukuguqulwa zibe kagesi, lapho imvamisa (amplitude) kuyahlukahluka ngokufanele;

- wamanje okuholela is amasampuli, isb kukhona izibonelo zalokho yayo (ngesinye isikhathi besho noma ebamba kanambambili wekhodi Imininingwane yomsindo).

I kwaphumela analog electronic yasekuqaleni ukugeleza umsindo ngcono, ayanda nobuningi we amasampula isampuli futhi esephepheni ukujula.

Ngamanye amazwi, lokufaka ikhodi ulwazi alalelwayo - kuyinqubo ejwayelekile zokuguqula isignali eziningi analog ibe digital, okuhloswe kucutshungulwe kudivayisi ezifanele. Ake sicabangele izinyathelo kanye nezindlela digitizing umsindo.

Discretization ifreyimu isikhathi - luyisisekelo digitizing. Ngokusho Kotel'nikova theorem, le Analogue uphawu lukagesi kungenziwa computer ngokufunda isinyathelo esithile uchungechunge okuqhubekayo yamanani amplitude yayo. Imvamisa ifundeke kufanele okungenani kabili nobuningi umkhawulo we isignali main. Uma kudingeka, digitizing Analogue "ikhodi yomthombo" ukuze imvamisa yokusebenza 0-20 kHz izibonelo zalokho okufanele kwenziwe ezingeqile kwezingama-40 eziyinkulungwane. Times yesibili (40 kHz) ngayinye. Isampula eyenani kokulinganisela ngesekhondi analog isignali umthombo (izibonelo zalokho, imvamisa amasampuli). Njengoba kwanda isampula inyuka hhayi kuphela izinga kodwa futhi ivolumu kokusakaza okuholela idatha.

Futhi, kungenzeka umsindo Imininingwane esephepheni kwenziwa ngezinye izindlela. Njengoba, kwenta sibonelo, ngekuletsa digitizing le quantizer nonuniform, ngezinye izikhathi ebizwa ngokuthi logarithmic. Uma usebenzisa lonke amplitude ububanzi kunemibandela kuhlukaniswe nge izindinganiso eziphakeme futhi ongaphakeme. Ngaphezu kwalokho wekhodi Imininingwane umsindo kwenzeka ngokusebenzisa esiningi amazinga quantization ezindaweni amplitude lwenani elincane (kanye noHezekeli). Nokho, phawula ukuthi inani eliphelele amazinga uhlala iyafana umfaniswano quantization indlela (PCM).

Indlela ehlukile ngokuphelele ukusebenza enye wekhodi indlela. Ibizwa ngokuthi "Pulse Ukwahlukaniswa Ikhodi Ukushintshashintsha» (DPCM). Nge indlela esinjalo ngaphansi quantization we amplitude we isignali oqondile nokubaluleka kwalo isihlobo. Ngenxa yalokho kungenzeka ukufeza nokwehlisa ivolumu elalihlala idatha, kusukela indlela siqhutshwa ukuqagela okwalandela isignali amasampula yasekuqaleni.

Esephepheni kanye ukucutshungulwa komsindo zolwazi ezichazwe kule iphepha kudinga kokwenza ukuguqulwa "analog-to-digital". Le nqubo ibizwa kusetshenziswa i ADC (analog-to-digital Converter). Nge lo msebenzi, idivayisi ngamunye ubhekene umnikazi ikhompyutha nsuku ifakwe ikhadi umsindo (kuleli cala kukhona inqubo reverse - ethola isiginali ye-analog kusukela emfudlaneni digital).

ADC imisebenzi yilena elandelayo:

- elinganiselwe imvamisa-bandwidth. Ukusebenzisa umshini, yezingxenye isignali bafa, imvamisa zazo - ezingaphezu kwesigamu imvamisa izibonelo zalokho (isizathu esesichaziwe).

- Ukukhethwa lamanani amplitude njalo ngezikhathi ezithile. I kwaphumela isiginali ye-analog is emelelwa ukulandelana izingcezu eyodwa obuhlukahlukene umfutho (discretization).

- yomiselela eziningi wathola izingcezu namagugu abo abaseduze kusuka eqoqweni esinqunyiwe (quantization).

- Ukuguqula ngamunye value quantized yenomboro okunemibandela amazinga quantization (inani ngalinye - inombolo yayo ye-serial). Lena esigabeni yokugcina ibhadalele.