?HOW CDs WORK

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HOW CDs WORK ? 3 Attapon Ashinetongkhum 48057053) Payveen Suwannawat 48050275 Surawut Suntalodom 48057692) Pipat Shutishupibul 48057478 Pipatpong Tuntivaranon 48050249 

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Introduction of CDs 60056 " ‎Cea iraa aaa is‏ رز ‎el Briere‏ ات زد تست ببس زد 0 ‎comethestandardme‏ ‏00071101511017 ‏1 كع رد تم 06 

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017075010018 Tofitmorethan 783meg es(MB)ontoa disco 711748 1771611845 Cease 510 tameter requiresthatth ‏ترس نیزر وت‎ . 1۷ ‎i‏ انهه كا 26 6 9 0 fis (4/700) aminch(7.2mm) thick. 7 ‎J‏ الور ‎ ‎ 

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"010750100118 16 0 ‏ل زا ا‎ anaes ingfromtheinsideof the disctothe outside. Thefact that thespiraltrackstartsat thec esata ‏ا‎ Le De aa as eee aaa CD ‏ال ل‎ ereare now plastic baseball cardsandbust nesscardsthat youcanputina CD player. 

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"011 0875]0:1100118 0621 1115 Tab pans ea enn cs ares eee areeacho.5 microns wide,aminimum of 0.8 amicronslongand725 nanometers high. (A ‏ی‎ Ost wees pn assets ca ‏)وله جا م‎ ] oma ca aly ‏ك6 و ی ری ریا‎ LE ERTS 

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)21( ۹۷ ۶ 1۲۷ 61۱۵۲۵۲ ۹911۱5 ۲۲۱۵ 1156, 1115 ert ese ‏ار ی تال متس تین‎ a nto epending on whichtrackis being read A 2051 andalenssystemfocusinonandreadthebumps, * Ktrackingmechanismmoves thelaser assembly sot fat thelaser sheamcan follow thespiraltrack. Thet ‎ey ne ame nen Tne‏ ی دیدرت و ‎Ce mea ues‏ 

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WhattheCD Player Does: La Soa prea Inside the CD player, thereia good bit of computer Dero LMT NR OC LOR RM Ce OM Ra CC OT derstandable data blocksandsending themeithe ۲۱0۵/۵۵ <09< 

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0” ‏تا رتست‎ eping thelaser beamc ‏مت ید‎ b eae rack, This centering? aaa tS gsystem. Thetrackin ۲ ‏رت درد‎ eCD,hastocontinual ‏علانكء 1716077 زا‎ 05 muta ۷۵۶ 

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CDEncodingissues: Bre ease ‏یر‎ PD) ۲ Maa eae ce sara aaa Leama) ل ل ‎earenobumpsinthedata track‏ = Becausethelaser wants to heabletomove between so CY aaa Tae CU Berea ae ana ABA GLY fe hedrive whereitis onthedisc. = Because thelaser maymisreada bump, thereneedito 6 ‏6517ل ثم 6 كصفمء وشاع ومع - هوهو‎ 0]6-617 se 

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“THANK YOU” 

HOW CDs WORK ? By Attapon Attapon Ashinetongkhum Ashinetongkhum 48057053 48057053 Paveen Paveen Suwannawat Suwannawat 48050215 48050215 Surawut Surawut Suntalodom Suntalodom 48051692 48051692 Pipat Pipat Shutishupibul Shutishupibul 48051478 48051478 Pipatpong Pipatpong Tuntivaranon Tuntivaranon 48050249 48050249 Introduction of CDs  CDs CDsare areeverywhere everywherett hese hesedays. days.Whether Whetherth th ey eyare areused usedto tohold holdmu mu sic, sic,data dataor orcomputer computer software, software,they theyhave havebe be come comethe thestandard standardme me dium diumfor fordistributin distributin gglarge largequantities quantitiesof ofii nformation nformationin ina areli reli able ablepackage. package. Understanding Understandingthe theCD: CD:Material Material   To Tofit fitmore morethan than783 783meg meg abytes abytes(MB) (MB)onto ontoa adisc discoo nly nly4.8 4.8inches inches(12 (12cm) cm)in indd iameter iameterrequires requiresthat thatth th eeindividual individualbytes bytesbe bever ver yysmall. small. A ACD CDis isa afairly fairlysimple simplepie pie ce ceof ofplastic, plastic,about aboutfour fouroo ne-hundredths ne-hundredths(4/100) (4/100)of of an aninch inch(1.2 (1.2mm) mm)thick. thick.M M ost ostof ofa aCD CDconsists consistsof ofan anii njection-molded njection-moldedpiece pieceof of clear clearpolycarbonate polycarbonateplas plas tic tic.. Understanding Understandingthe theCD: CD:The TheSpiral Spiral  A ACD CDhas hasa asingle singlespiral spiraltrack trackof ofdata, data,circl circl ing ingfrom fromthe theinside insideof ofthe thedisc discto tothe theoutside. outside. The Thefact factthat thatthe thespiral spiraltrack trackstarts startsat atthe thecc enter entermeans meansthat thatthe theCD CDcan canbe besmaller smallertha tha n n4.8 4.8inches inches(12 (12cm) cm)if ifdesired, desired,and andin infact factth th ere ereare arenow nowplastic plasticbaseball baseballcards cardsand andbusi busi ness nesscards cardsthat thatyou youcan canput putin ina aCD CDplayer. player. Understanding Understandingthe theCD: CD:Bumps Bumps  The Theelongated elongatedbumps bumpsthat thatmake makeup upthe thetrack track are areeach each0.5 0.5microns micronswide, wide,a aminimum minimumof of0.8 0.8 33microns micronslong longand and125 125nanometers nanometershigh. high.(A (A nanometer nanometeris isa abillionth billionthof ofa ameter.) meter.)Lookin Lookin ggthrough throughthe thepolycarbonate polycarbonatelayer layerat atthe thebu bu mps, mps,they theylook looksomething somethinglike likethis this CD CDPlayer PlayerComponents Components    A Adrive drivemotor motorspins spinsthe thedisc. disc.This Thisdrive drivemotor motoris isprec prec isely iselycontrolled controlledto torotate rotatebetween between200 200and and500 500rpm rpmdd epending ependingon onwhich whichtrack trackis isbeing beingread. read. A Alaser and anda alens lenssystem systemfocus focusin inon onand andread readthe thebumps. bumps. A Atracking trackingmechanism mechanismmoves movesthe thelaser laserassembly assemblyso sott hat hatthe thelaser's laser'sbeam beamcan canfollow followthe thespiral spiraltrack. track.The Thett racking rackingsystem systemhas hasto tobe beable ableto tomove movethe thelaser laserat atmic mic ron ronresolutions. resolutions. What Whatthe theCD CDPlayer PlayerDoes: Does:La La ser serFocus Focus Inside the CD player, there i a good bit of computer technology involved in forming the data into un derstandable data blocks and sending them eithe r to the DAC What Whatthe theCD CDPlayer PlayerDoes: Does:Trackin Trackin gg  The Thehardest hardestpart partis iske ke eping epingthe thelaser laserbeam beamcc entered enteredon onthe thedata datatt rack. rack.This Thiscentering centeringii ssthe thejob jobof ofthe thetrackin trackin ggsystem system..The Thetrackin trackin ggsystem, system,as asit itplays playsth th eeCD, CD,has hasto tocontinual continual ly lymove movethe thelaser laserout out ward. ward. CD CDEncoding EncodingIssues Issues To Tounderstand understandhow howdata dataare arestored storedon ona aCD CD    Because Becausethe thelaser is istracking trackingthe thespiral spiralof ofdata datausing using the thebumps, bumps,there therecannot cannotbe beextended extendedgaps gapswhere wherether ther eeare areno nobumps bumpsin inthe thedata datatrack track Because Becausethe thelaser laserwants wantsto tobe beable ableto tomove movebetween betweenso so ngs, ngs,data dataneeds needsto tobe beencoded encodedinto intothe themusic musictelling tellingtt he hedrive drive"where "whereit itis" is"on onthe thedisc. disc. Because Becausethe thelaser lasermay maymisread misreada abump, bump,there thereneed needto to be beerror-correcting error-correctingcodes codesto tohandle handlesingle-bit single-biterror error s. s. “ THANK YOU ”