Lub teeb liab digital baseband yog hluav taws xob waveform uas sawv cev rau cov ntaub ntawv digital, uas tuaj yeem sawv cev los ntawm ntau qib lossis pulses. Muaj ntau hom digital baseband signals (tom qab no hu ua baseband signals). Daim duab 6-1 qhia ob peb lub hauv paus teeb liab waveforms, thiab peb yuav siv cov mem tes ua piv txwv.
1. Unipolar waveform
Raws li pom nyob rau hauv daim duab 6-1(a), qhov no yog qhov yooj yim tshaj plaws baseband teeb liab waveform. Nws siv qib zoo thiab qib xoom los sawv cev rau tus lej binary "1" thiab "0," lossis nws siv qhov muaj lossis tsis muaj pulses los sawv cev "1" thiab "0" hauv lub sijhawm cim. yog tias tsis muaj lub sijhawm nruab nrab ntawm hluav taws xob pulses, lub polarity yog ib leeg, thiab nws yooj yim tsim los ntawm TTL thiab CMOS circuits. Nws tuaj yeem xa mus rau hauv lub khoos phis tawj lossis nruab nrab ntawm cov khoom nyob ze, zoo li lub rooj tsav xwm luam tawm thiab lub chassis.
2. Bipolar waveform
Nws siv cov qib siab zoo thiab tsis zoo los sawv cev rau tus lej binary "1" thiab "0," raws li qhia hauv daim duab 6-1(b).Vim tias qib zoo thiab qhov tsis zoo muaj qhov sib npaug ntawm cov amplitudes thiab cov polarities, tsis muaj DC tivthaiv thaum Qhov tshwm sim ntawm "1" thiab "0" tshwm sim, uas yog qhov tsim nyog rau kev sib kis hauv cov channel, thiab theem kev txiav txim siab rau kev rov kho cov teeb liab ntawm qhov kawg tau txais yog xoom, Yog li ntawd, nws tsis cuam tshuam los ntawm kev hloov pauv ntawm cov yam ntxwv channel, thiab lub peev xwm tiv thaiv kev cuam tshuam kuj muaj zog. ITU-T's V.24 interface tus qauv thiab American Electrotechnical Association's (EIA) RS-232C interface tus qauv siv ob qho tib si bipolar waveforms.
3. Unipolar rov-rau-zero waveform
Lub active pulse dav ntawm qhov rov-rau-zero (RZ) waveform yog tsawg dua lub cim dav T, uas txhais tau hais tias lub teeb liab voltage ib txwm rov qab mus rau xoom ua ntej lub sij hawm txiav tawm ntawm lub cim, raws li qhia nyob rau hauv daim duab 6-1 (c ).show. Feem ntau, qhov rov qab-rau-zero waveform siv ib nrab-lub luag haujlwm code, uas yog, lub luag haujlwm voj voog (T / TB) yog 50%, thiab cov ntaub ntawv sijhawm tuaj yeem raug rho tawm ncaj qha los ntawm unipolar RZ waveform. hloov pauv waveform.
sib raug rau qhov rov-rau-zero waveform. Lub unipolar thiab bipolar waveforms saum toj no yog tsis rov qab-rau-zero (NRZ) waveforms nrog lub luag haujlwm voj voog ntawm.
4.Bipolar rov-rau-zero waveform
Nws yog daim ntawv rov-rau-zero ntawm bipolar waveform, raws li qhia hauv daim duab 6-1(d). Nws ua ke cov yam ntxwv ntawm bipolar thiab rov-rau-zero waveforms. Vim tias muaj pes tsawg lub sijhawm nruab nrab ntawm cov pulses uas nyob ib sab, tus txais tau yooj yim txheeb xyuas lub sijhawm pib thiab xaus ntawm txhua lub cim, kom tus neeg xa khoom thiab tus txais tuaj yeem tswj xyuas qhov tseeb me ntsis synchronization. Qhov kom zoo dua no ua rau bipolar nulling waveforms pab tau.
5. Sib txawv waveform
Hom waveform no qhia cov lus nrog kev hloov pauv thiab hloov ntawm qib ntawm cov cim uas nyob ib sab, tsis hais lub peev xwm lossis polarity ntawm lub cim nws tus kheej, raws li pom hauv daim duab 6-1(e). Hauv daim duab, "1" yog sawv cev los ntawm qib dhia, thiab "0" yog sawv cev los ntawm qib tsis hloov. Tau kawg, cov kev cai saum toj no kuj tuaj yeem thim rov qab. Txij li qhov sib txawv waveform sawv cev rau cov lus los ntawm cov txheeb ze hloov pauv ntawm cov qib mem tes uas nyob ib sab, nws tseem hu ua tus txheeb ze code waveform thiab sib raug zoo, qhov ua ntej unipolar lossis bipolar waveform yog hu ua qhov code waveform. Siv cov qauv sib txawv los xa cov lus tuaj yeem tshem tawm cov txiaj ntsig ntawm thawj lub xeev ntawm cov cuab yeej, tshwj xeeb tshaj yog nyob rau hauv theem kev hloov kho. Nws tuaj yeem siv los daws qhov teeb meem ntawm cov cab kuj theem ambiguity.
6. Ntau theem waveform
Tsuas muaj ob theem ntawm qhov saum toj no waveforms, uas yog, ib lub cim binary sib raug rau ib lub mem tes. Txhawm rau txhim kho kev siv band zaus, siv ntau theem waveform lossis ntau tus nqi waveform. Daim duab 6-1(f) qhia txog plaub-theem waveform 2B1Q (ob qhov khoom yog sawv cev los ntawm ib qho ntawm plaub theem), qhov twg 11 sawv cev +3E, 10 sawv cev +E, 00 sawv cev -E, thiab 01 sawv cev -3E. multi-level waveform yog siv nyob rau hauv high-ceev cov ntaub ntawv kis tau tus mob nrog tsawg zaus bands. Txij li thaum ib tug mem tes ntawm ntau theem waveform sib raug rau ntau binary codes, tus nqi me ntsis yog nce nyob rau hauv cov xwm txheej ntawm tib baud tus nqi (tib kis bandwidth). Nws tau siv dav.
Nws yuav tsum tau muab sau tseg tias lub waveform ntawm ib tug mem tes sawv cev rau cov ntaub ntawv cim tsis tas yuav rectangular. Raws li qhov xav tau tiag tiag thiab cov xwm txheej channel, lwm cov ntaub ntawv xws li Gaussian pulse, tsa cosine mem tes, thiab lwm yam tuaj yeem siv tau. Tab sis tsis muaj teeb meem dab tsi ntawm waveform siv, lub teeb liab digital baseband tuaj yeem sawv cev ua lej. Yog hais tias cov waveforms sawv cev rau cov cim zoo ib yam tab sis cov qib qhov tseem ceeb sib txawv.
Nov yog "Introduction to Digital Baseband Signal Waveforms" coj los rau koj los ntawm Shenzhen HDV Phoelectron Technology Co., Ltd., Kuv vam tias tsab xov xwm no tuaj yeem pab koj kom koj paub ntau ntxiv. Dhau li ntawm tsab xov xwm no yog tias koj tab tom nrhiav rau lub tuam txhab kev sib txuas lus zoo fiber ntau cov khoom lag luam koj tuaj yeem xav txogtxog peb.
Shenzhen HDV photoelectric Technology Co., Ltd. yog lub chaw tsim khoom ntawm cov khoom sib txuas lus. Tam sim no, cov cuab yeej tsim tawm npog covONU series, Optical module series, OLT series, thiabtransceiver series. Peb tuaj yeem muab cov kev pabcuam customized rau cov xwm txheej sib txawv. Zoo siab txais tossab laj.
