_gps ppt
TRANSCRIPT
Introduction to the Introduction to the Global Positioning SystemGlobal Positioning System
An AAPT/PTRA WorkshopAn AAPT/PTRA Workshop
Fred NelsonFred Nelson
Manhattan High SchoolManhattan High School
What is the GPS?What is the GPS? Orbiting navigational satellites Orbiting navigational satellites
Transmit position and time dataTransmit position and time data Handheld receivers calculateHandheld receivers calculate
latitudelatitude longitudelongitudealtitudealtitudevelocityvelocity
Developed by Developed by Department Department of Defenseof Defense
History of the GPSHistory of the GPS1969—Defense Navigation Satellite 1969—Defense Navigation Satellite
System (DNSS) formedSystem (DNSS) formed1973—NAVSTAR Global Positioning 1973—NAVSTAR Global Positioning
System developedSystem developed1978—first 4 satellites 1978—first 4 satellites
launchedlaunched
Delta rocket launchDelta rocket launch
History of the GPSHistory of the GPS 1993—24th satellite 1993—24th satellite
launched; initial launched; initial operational capabilityoperational capability
1995—full operational 1995—full operational capabilitycapability
May 2000—Military May 2000—Military accuracy available to accuracy available to all usersall users
Components of the SystemComponents of the SystemSpace segmentSpace segment 24 satellite vehicles24 satellite vehicles Six orbital planesSix orbital planes
Inclined 55Inclined 55o o with respect to with respect to equatorequator
Orbits separated by 60Orbits separated by 60oo
20,200 km elevation above 20,200 km elevation above EarthEarth
Orbital period of 11 hr 55 Orbital period of 11 hr 55 minmin
Five to eight satellites Five to eight satellites visible from any point on visible from any point on EarthEarth
Block I Satellite VehicleBlock I Satellite Vehicle
The GPS ConstellationThe GPS Constellation
GPS Satellite VehicleGPS Satellite Vehicle Four atomic clocksFour atomic clocks Three nickel-cadmium Three nickel-cadmium
batteriesbatteries Two solar panelsTwo solar panels
Battery chargingBattery charging Power generationPower generation 1136 watts1136 watts
S band antenna—satellite S band antenna—satellite controlcontrol
12 element L band antenna—12 element L band antenna—user communicationuser communication
Block IIF satellite vehicle Block IIF satellite vehicle (fourth (fourth generation)generation)
GPS Satellite VehicleGPS Satellite Vehicle
WeightWeight 2370 pounds2370 pounds
HeightHeight 16.25 feet16.25 feet
WidthWidth 38.025 feet including 38.025 feet including
wing spanwing span Design life—10 yearsDesign life—10 years
Block IIR satellite vehicle Block IIR satellite vehicle assembly at Lockheed assembly at Lockheed Martin, Valley Forge, PAMartin, Valley Forge, PA
Components of the SystemComponents of the SystemUser segmentUser segment GPS antennas & receiver/processorsGPS antennas & receiver/processors PositionPosition VelocityVelocity Precise timingPrecise timing Used byUsed by
AircraftAircraft Ground vehiclesGround vehicles ShipsShips IndividualsIndividuals
Components of the SystemComponents of the System
Ground control segmentGround control segmentMaster control stationMaster control station
Schreiver AFB, ColoradoSchreiver AFB, ColoradoFive monitor stationsFive monitor stationsThree ground antennasThree ground antennasBackup control systemBackup control system
GPS Communication and ControlGPS Communication and Control
GPS Ground Control StationsGPS Ground Control Stations
How does GPS work?How does GPS work?
Satellite rangingSatellite rangingSatellite locationsSatellite locationsSatellite to user distanceSatellite to user distanceNeed four satellites to determine positionNeed four satellites to determine position
Distance measurementDistance measurementRadio signal traveling at speed of lightRadio signal traveling at speed of lightMeasure time from satellite to userMeasure time from satellite to user
Low-tech simulationLow-tech simulation
How does GPS work?How does GPS work?
Pseudo-Random CodePseudo-Random Code Complex signalComplex signal Unique to each Unique to each
satellitesatellite All satellites use All satellites use
same frequencysame frequency ““Amplified” by Amplified” by
information theoryinformation theory EconomicalEconomical
How does GPS work?How does GPS work? Distance to a satellite is determined by measuring how Distance to a satellite is determined by measuring how
long a radio signal takes to reach us from that satellite. long a radio signal takes to reach us from that satellite. To make the measurement we assume that both the To make the measurement we assume that both the
satellite and our receiver are generating the same satellite and our receiver are generating the same pseudo-random codes at exactly the same time. pseudo-random codes at exactly the same time.
By comparing how late the satellite's pseudo-random By comparing how late the satellite's pseudo-random code appears compared to our receiver's code, we code appears compared to our receiver's code, we determine how long it took to reach us. determine how long it took to reach us.
Multiply that travel time by the speed of light and you've Multiply that travel time by the speed of light and you've got distance. got distance.
High-tech simulationHigh-tech simulation
How does GPS work?How does GPS work?
Accurate timing is the key to measuring Accurate timing is the key to measuring distance to satellites.distance to satellites.
Satellites are accurate because they have Satellites are accurate because they have four atomic clocks ($100,000 each) on four atomic clocks ($100,000 each) on board. board.
Receiver clocks don't have to be too Receiver clocks don't have to be too accurate because an extra satellite range accurate because an extra satellite range measurement can remove errors. measurement can remove errors.
How does GPS work?How does GPS work? To use the satellites as references for range To use the satellites as references for range
measurements we need to know exactly where they are. measurements we need to know exactly where they are. GPS satellites are so high up their orbits are very GPS satellites are so high up their orbits are very
predictable. predictable. All GPS receivers have an almanac programmed into All GPS receivers have an almanac programmed into
their computers that tells them where in the sky each their computers that tells them where in the sky each satellite is, moment by moment. satellite is, moment by moment.
Minor variations in their orbits are measured by the Minor variations in their orbits are measured by the Department of Defense. Department of Defense.
The error information is sent to the satellites, to be The error information is sent to the satellites, to be transmitted along with the timing signals. transmitted along with the timing signals.
GPS Position DeterminationGPS Position Determination
System PerformanceSystem Performance Standard Positioning Standard Positioning
SystemSystem 100 meters horizontal accuracy100 meters horizontal accuracy 156 meters vertical accuracy156 meters vertical accuracy Designed for civilian useDesigned for civilian use No user fee or restrictionsNo user fee or restrictions
Precise Positioning Precise Positioning SystemSystem 22 meters horizontal accuracy22 meters horizontal accuracy 27.7 meters vertical accuracy27.7 meters vertical accuracy Designed for military useDesigned for military use
System PerformanceSystem Performance
Selective availabilitySelective availability Intentional degradation of signalIntentional degradation of signal Controls availability of system’s full capabilitiesControls availability of system’s full capabilities Set to zero May 2000Set to zero May 2000 ReasonsReasons
Enhanced 911 serviceEnhanced 911 service Car navigationCar navigation Adoption of GPS time standardAdoption of GPS time standard RecreationRecreation
System PerformanceSystem Performance
The earth's ionosphere and atmosphere The earth's ionosphere and atmosphere cause delays in the GPS signal that cause delays in the GPS signal that translate into position errors. translate into position errors.
Some errors can be factored out using Some errors can be factored out using mathematics and modeling. mathematics and modeling.
The configuration of the satellites in the The configuration of the satellites in the sky can magnify other errors. sky can magnify other errors.
Differential GPS Differential GPS can reduce errors.can reduce errors.
Application of GPS TechnologyApplication of GPS Technology
Location - determining a basic positionLocation - determining a basic positionNavigation - getting from one location to Navigation - getting from one location to
another another Tracking - monitoring the movement of Tracking - monitoring the movement of
people and things people and things Mapping - creating maps of the world Mapping - creating maps of the world Timing - bringing precise timing to the Timing - bringing precise timing to the
world world
Application of GPS TechnologyApplication of GPS Technology Private and recreationPrivate and recreation
Traveling by carTraveling by car Hiking, climbing, bikingHiking, climbing, biking Vehicle controlVehicle control
Mapping, survey, geologyMapping, survey, geology English Channel TunnelEnglish Channel Tunnel AgricultureAgriculture AviationAviation
General and commercialGeneral and commercial SpacecraftSpacecraft
MaritimeMaritime
GPS NavigationGPS Navigation
GPS NewsGPS News
http://www.gpseducationresource.com/gpshttp://www.gpseducationresource.com/gpsnews.htmnews.htm
One–page reading exerciseOne–page reading exerciseCenter of page—main topicCenter of page—main topicFour corners—questions & answers from Four corners—questions & answers from
readingreadingFour sides—specific facts from readingFour sides—specific facts from readingSpaces between—supporting ideas, Spaces between—supporting ideas,
diagrams, definitionsdiagrams, definitionsArticle citation on back of pageArticle citation on back of page
Military Uses for the GPSMilitary Uses for the GPS
Operation Desert StormOperation Desert Storm Featureless terrainFeatureless terrain Initial purchase of 1000 portable commercial Initial purchase of 1000 portable commercial
receiversreceivers More than 9000 receivers in use by end of the More than 9000 receivers in use by end of the
conflictconflict Foot soldiersFoot soldiers VehiclesVehicles AircraftAircraft Marine vesselsMarine vessels
GeocachingGeocaching
Cache of goodies Cache of goodies established by individualsestablished by individuals
Coordinates published on Coordinates published on WebWeb
Find cacheFind cache Leave a messageLeave a message Leave some treasureLeave some treasure Take some treasureTake some treasure
http://http://www.geocaching.comwww.geocaching.com//
Handheld GPS ReceiversHandheld GPS Receivers Garmin eTrexGarmin eTrex
~$100~$100
Garmin-12Garmin-12 ~$150~$150
Casio GPS Casio GPS wristwatchwristwatch ~$300~$300
The GPS StoreThe GPS Store
GPS Operation JargonGPS Operation Jargon
““Waypoint” or “Landmark”Waypoint” or “Landmark” ““Track” or “Heading”Track” or “Heading” ““Bearing”Bearing” CDICDI RouteRoute MarkMark GOTOGOTO
GPS/Digital GPS/Digital TelephoneTelephone
GPS WebsitesGPS WebsitesUSNO NAVSTAR HomepageUSNO NAVSTAR Homepage
Info on the GPS constellation How Stuff Works GPSHow Stuff Works GPS
Good everyday language explanationTrimble GPS tutorialTrimble GPS tutorial
Flash animationsGPS Waypoint registryGPS Waypoint registry
Database of coordinates
Classroom ApplicationsClassroom Applications PhysicsPhysics
Distance, velocity, timeDistance, velocity, time Orbital conceptsOrbital concepts
Earth ScienceEarth Science MappingMapping SpacecraftSpacecraft
Environmental ScienceEnvironmental Science Migratory patternsMigratory patterns Population distributionsPopulation distributions GLOBE ProgramGLOBE Program
MathematicsMathematics GeographyGeography TechnologyTechnology
Classroom ApplicationsClassroom Applications
CareersCareers AerospaceAerospace
Satellite vehiclesSatellite vehicles Launch vehiclesLaunch vehicles
Hardware engineeringHardware engineering Ground control systemsGround control systems User systemsUser systems
Software engineeringSoftware engineering Research careersResearch careers
In and Out of the ClassroomIn and Out of the Classroom
Problem SolvingProblem Solving
Sometimes the solution is over your Sometimes the solution is over your head . . .head . . .
Kansas Science Education Kansas Science Education StandardsStandards
Students will:Students will:demonstrate the fundamental abilities demonstrate the fundamental abilities
necessary to do scientific inquirynecessary to do scientific inquiryapply different kinds of investigations to apply different kinds of investigations to
different kinds of questionsdifferent kinds of questionsexpand their use and understanding of expand their use and understanding of
science and technologyscience and technology
National Science Education National Science Education Teaching StandardsTeaching Standards
Teachers of science Teachers of science Plan an inquiry-based science program for Plan an inquiry-based science program for
their studentstheir studentsGuide and facilitate learningGuide and facilitate learningDesign and manage learning Design and manage learning
environments that provide students with environments that provide students with the time, space, and resources needed for the time, space, and resources needed for learning sciencelearning science
National Science Education National Science Education Content StandardsContent Standards
. . . all students should develop. . . all students should develop Abilities necessary to do scientific inquiry Abilities necessary to do scientific inquiry Understandings about scientific inquiryUnderstandings about scientific inquiry Abilities of technological design Abilities of technological design Understandings about science and technologyUnderstandings about science and technology Understandings aboutUnderstandings about
Motions and forcesMotions and forces Population growth Population growth Natural resources Natural resources Environmental quality Environmental quality Science and technology in local, national, and global challengesScience and technology in local, national, and global challenges
““Where does he get those Where does he get those wonderful toys?”wonderful toys?”
Student-centeredStudent-centered High interest High interest Outdoors Outdoors High visibility High visibility Integrated curriculumIntegrated curriculum InquiryInquiry
Thanks for your interest in the Thanks for your interest in the Global Positioning SystemGlobal Positioning System
For more information or a copy of For more information or a copy of these slidesthese slides
[email protected]@cs.com