sensors, circuits, and satellites lesson 4: digital ...§ receiver circuit § solar cell §...
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Sensors, Circuits, and Satellites revisedApril2016
DevelopedunderGSFCIRADAwardFY13-297 page 1
Sensors,Circuits,andSatellitesLesson4:DigitalCommunication
Sensors,Circuit,andSatellitesisacollectionofclassroomlessonscreatedbyNASA’sAuramissioneducationandoutreachthatexploretheelectromagneticspectrumandNASAremotesensinginstrumentsusingstudentassembledcircuits.Theselessonsintegrateinquirywithactive-learningexperiencestoengagestudentsinthepropertiesofelectromagneticenergyandremotesensing.TheinvestigationsaresequencedtohelpthelearnerconstructtheirknowledgeabouttheelectromagneticspectrumwhileofferingrealworldexamplesfromNASA.Credits:Dr.DeborahRoberts-Harris,Dept.ofTeacherEducationattheUniversityofNewMexicoGingerButcher,SeniorNASAEducationSpecialist,ScienceSystemsandApplications,Inc.DevelopedincollaborationwithlittleBitsElectonics™viaanInternalResearchandDevelopment(IRADFY13-297)awardfromNASAGoddardSpaceFlightCenterandcontinuedcollaborationunderNASASpaceActAgreementSAA5-2013-3-N15210
Sensors, Circuits, and Satellites revisedApril2016
DevelopedunderGSFCIRADAwardFY13-297 page 2
Lesson4:DigitalCommunicationSummary:ThislessonisademonstrationaboutelectromagneticenergyandhowthatenergyistransferredviavisibleandIRlightwavestosoundenergy(digitalsignals).Studentswillinvestigatehowthelengthofthewaveaffectshowlightenergyistransmitted.Conceptsofdigitalsignal,visible,infraredormicrowavewavesareintroduced.StudentObjectives:Studentswillanalyzethedifferencebetweenthetransmissionpropertiesofdifferentelectromagnetic(light)wavesusingadigitalsign.
KeyTerms:electromagneticspectrum,digitalsignal,visible,infraredandmicrowave.
ApproximateTime:45–60minutes
Materials:• littleBits™components:power,microphone,audiocable,brightLED,andwire
(foreaseofuse),alsoforthesecondcircuit:power,lightsensor,speaker,andwire
o ALTERNATIVEMATERIALS*–FromSection5,ActiveAstronomyEducatorGuidefromtheSOFIAmission
§ InfraredLightEmittingDiode(LED)§ 0.22μF(microfarad)Capacitor§ AudioCablewith1/8”mini-plugononeend§ 5JumperCableswithalligatorclipsonbothends§ AABattery§ AAbatteryholder§ ReceiverCircuit§ Solarcell§ Amplifier/Speaker§ AudioCablewith1/8”mini-plugononeend§ 2JumperCableswithalligatorclipsonbothends§ 9VoltBatteryforAmplifier/Speaker
• Flashlight• MP3player• Imageoftheelectromagneticspectrum• Whitetissuepaper,fabricpiecesandplasticbags• Videogamecontroller
NGSS–DisciplinaryCoreIdeas• MS-PS4-2WavesandTheirApplicationsinTechnologiesforInformation
Transfer-Developanduseamodeltodescribethatwavesarereflected,absorbed,ortransmittedthroughvariousmaterials.[ClarificationStatement:Emphasisisonbothlightandmechanicalwaves.Examplesofmodelscouldincludedrawings,simulations,andwrittendescriptions.][AssessmentBoundary:Assessmentislimitedtoqualitativeapplicationspertainingtolightandmechanicalwaves.]
Sensors, Circuits, and Satellites revisedApril2016
DevelopedunderGSFCIRADAwardFY13-297 page 3
• MS-PS4.3:InformationTechnologiesandInstrumentationDigitizedinformationcanbetransmittedoverlongdistanceswithoutsignificantdegradation.High-techdevices,suchascomputersorcellphones,canreceiveanddecodeinformation—convertitfromdigitizedformtovoice—andviceversa.[ClarificationStatement:Emphasisisonabasicunderstandingthatwavescanbeusedforcommunicationpurposes.Examplescouldincludeusingfiberopticcabletotransmitlightpulses,radiowavepulsesinwifidevices,andconversionofstoredbinarypatternstomakesoundortextonacomputerscreen.][AssessmentBoundary:Assessmentdoesnotincludebinarycounting.Assessmentdoesnotincludethespecificmechanismofanygivendevice.]
NGSS–Cross-cuttingconcepts• StructureandFunction:Structurescanbedesignedtoserveparticularfunctions
bytakingintoaccountpropertiesofdifferentmaterials,andhowmaterialscanbeshapedandused.
• Patterns:Graphsandchartscanbeusedtoidentifypatternsindata.
Engage:(Teachercandemo,oraskforstudentvolunteer). 1.Shineaflashlightontothelightsensorinthereceivercircuitandtryto
makeanoise. 2.Askthestudents:Whathappens?Canyoumakeanoise?
3.Guidestudentstonoticethattheflashlightwillmakeaclickingsound whenthesignal(lightwavesfromtheflashlight)isinterrupted.Whentheflashlightmovesaway,ormovesbackonyouwillgetasound-offandon.
Explain:
Sharewiththestudentsthatwhenthesensorturnsoffandon,thereisachangeinthesignaltoelectricalenergy.Thisisjustlikethebinarycodeusedbycomputersandotherdevicestoencodeinformation.Signalscanbecodedintoaseriesofpulses.Thesignalcanonlybeonoroff.Thesearecalleddigitalsignals.
Explore:
1. Puttogetheryourfirstcircuit:Transmitter(Power+Microphoneandaudiocable+MP3+BrightLED)+wireforeaseofuse
2. Puttogetheryoursecondcircuit:Receiver(Power+Lightsensor+Speaker)+wireforeaseofuse
3. PlayyourmusicandholdtheBrightLEDbitoverthelightsensorandthelightmodulates
4. NowchangebrightledtotheIRLEDbitoverthelightsensor-doesitsounddifferent?Howso?Recordyourfindingsinyourjournal.Whydoyouthinkthisishappening?
*Ifusingalternativematerials,seeset-upinstructionsonpages73-76ofSection5intheActiveAstronomyEducatorGuidetocompletesteps1&2
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Explain:Firstlet’slookathowtheenergyisbeingtransmitted.Whatisthefirstenergysource?Thebattery.ThebatteryenergyistransmittedtothedatastoredelectronicallyonMP3player,thentothelight.Thelightenergyistransferredtosoundenergyatthespeaker.
SowhyisthereadifferenceinthebrightlightandtheIRlight?Recordstudentideas.
Let’stakealookattheelectromagneticspectrum(showimage).
https://science.nasa.gov/ems/01_introWeuseelectromagneticwaveseveryday.Doyouknowofanythingthatuseselectromagneticwaves?Listentostudentideas.Electromagneticwavesareemittedbymanynaturalandman-madesources.Thesewavesareapartofourdailylives,whetherweareawareofthemornot.Wearewarmedbytheelectromagneticemissionsofthesun(sunburn?)andweseeusingthepartoftheelectromagneticspectrumthatoureyesdetectasvisiblelight.Infraredlightisnotpartofthevisiblelightspectrum,butasyoucansee,stillemitswavesthatcanbedetectedbysensors,andotherinstruments.Let’stakealookattheelectromagneticspectrum(showimage).
Givestudentorpairsofstudentsacopyoftheimageabove.Havethemrecordsomeobservationsaboutthechart.Then,asktheclass-Whatdoyounoticeabouthowlightwavesarearrangedonthespectrum?Longtoshort–lefttoright.IsthereadifferencebetweentheIRwavesandthevisiblelightwaves?Whatelsedoyounoticeaboutthischart?Inthenextpartoftheinvestigationwearegoingtoinvestigatehowthelengthofthewaveaffectshowlightenergyistransmitted.Explore:Foreachtypeoflight,wewilltesthowittransmitsenergythroughthreedifferentsubstances:tissuepaper,fabricandaplasticbag(Studentscomplete“DataCollectionVisibleLightandInfraredLight”Sheet).CONNECTION:NASAcommunicateswithsatellites,astronauts,andevenRoversonMarsbydigitalsignalsusingelectromagneticwaves.(Welcometothedigitalage-digitalcommunicationispartofourdailylives.)Allthewavesthatmakeuptheelectromagneticspectrumtravelatexactlythesamespeedthroughspace,whichisthespeedoflight.
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DevelopedunderGSFCIRADAwardFY13-297 page 5
DataCollectionVisibleLightandInfraredLight
Materialbetweentransmitterandreceiver
Observationsw/brightLEDbit(visiblelight)
Observationsw/IRLEDbit(infraredlight)
Whitetissuepaper
Fabric
Plasticbag
DataCollectionMicrowaveLight
Materialbetweentransmitterandreceiver
Observationsw/microwavelight
Whitetissuepaper
Fabric
Plasticbag