×

# UH - ELET - ELET 2303; Week 1, Chapter 1 Notes - Class Notes

### Created by: Biatris Notetaker Elite Notetaker

Schools > University of Houston > Electrical Engineering > ELET > UH - ELET - ELET 2303; Week 1, Chapter 1 Notes - Class Notes
IntroductoryConcepts

IntroductiontoDigital1sand0s
•  Largepartoftheworldwidetelecommunicationsystemsfallsinthecategoryofdigital
systems.
•  DigitalSystemsdealwiththingsthatareinoneoftwodistinctstates.
Howitstarted
•  Itstartedwithatelegraph,simpledigitalsystemthatusedonlytwostatestorepresent
information

•  Thetelegraphsystemusedtwodistinct“symbols”totransmitinformation(words/numbers) •  Itusesshortandlongelectricpulses,thedotsanddashedofMorsecode(digital
representationofinformation).
•  Theelectricsignalsareeitheronoroffatalltimes.Theseelectricalsignalsarea
representationof1sand0s.
•  Exampleoftimingdiagramthatshowswhichstatethesystemisinanypointoftime.

1sand0s •  Thetwonumericdigits(1and0)arecalledbinarydigitsorbitsandrepresentthetwostates
ONandOFFrespectively.
•  LogicState:Digitalcircuitsobservethestateofeachcomponentandmakea"logical"decision. •  Howarethestatesof1and0representedelectronicallyinadigitalsystem? !   Inelectronicsystems,avoltagemustbeappliedtoacircuittocausecurrenttoflowthrough
theactivedeviceand"turniton"
!   Logiclevels:0isrepresentedbyalowvoltageand1byahighervoltage !   RepresentationofahighstateMUSTmatchthesystem !   Somedigitaldevicesareactivatedby(a)applyinghighvoltageswhileothersareactivatedby
(b)applyingalowvoltage.
•  Howhighthevoltagemustbetobeconsidera1or0? !   Itdependsonthetechnologyusedtoimplementthedigitalsystem.
Highervoltage=High1
Lowervoltage=Low0
Examplesoftwostatesdevices: a)  Alightbulb: offandon b)  Diode: conductingornotconducting c)  Relay: energizedornotenergized d)  Transistor: cutofforsaturation e)  Capacitor: chargeoruncharged

DigitalvsAnalog
•  Twowaysofrepresentingthenumericalvalueofquantities:analoganddigital

DigitalRepresentation
•  Thesequantitiesarerepresentedbysymbolscalleddigits.Digitalwavesarestepping,
squareanddiscrete.
Example:
Digitalrepresentationofoutdoortemperaturechangesindiscretesteps.
•  Digitalsystemsisacombinationofdevicesdesignedtomanipulatelogicalorphysical
quantitiesthatarerepresentedindigitalforms.
Example:familiardigitalsystems
Digitalcomputers Calculators Digitalaudio Videoequipment Telecommunicationsystem
•  Theyaredesignedtorespondpredictablytoinputvoltagesthatarewithindefineranges0
to1.
•  Indigitalsystems,theexactvalueofavoltageisNOTimportant.
Example:Ahighvoltageof3.7Vor4.3VwouldrepresenttheEXACTinformation.
•  Lessaffectedbynoise;fewererrors

Join more than 18,000+ college students at University of Houston who use StudySoup to get ahead