INSTITUTE OF TECHNOLOGY & MANAGEMENT PRESENTATION ON GPS PREPARED BY : KUNAL PRAKASH MISHRA ECE 4’th YR.
CONTENTS Introduction Working Different segments of GPS Primary function of GPS GPS position location principle PSEUDO RANDOM NOISE code Equations involved Sources of signal interference GPS receiver DGPS Applications of GPS
INTRODUCTIONIt is global positioning system used for positionlocation & navigation.It is a network of 24 NAVSTAR satellites orbitingaround earth at an altitude of approx. 20200 kms.In this system satellites are placed in MEOIt consists of satellites ,receivers & groundcontrol systems.It is operated on L –band frequency(1-2GHz).A GPS works in any weather condition
contd… It provides a direct readout of the presentposition of a GPS receiver with a typical accuracy of 30 m. The orbital period of a satellite is approx. one- half a sidereal day (11hr 58 min) LORAN is also used for position location There are three segments of a GPS & theyare:1. Control segment2. Space segment3. User segment
CONTROL SEGMENTA control segment is composed of :1.A master control station2.Four dedicated ground stations3.Six dedicated monitor stations
Three Segments of the GPS Space Segment User Segment Control Segment Ground AntennasMaster Station Monitor Stations
Control Segment US Space Command Cape Canaveral Hawaii Kwajalein Atoll Diego Garcia Ascension Is.Master Control Station Monitor Station Ground Antenna
User Segment Military. Search and rescue. Disaster relief. Surveying. Marine, aeronautical and terrestrial navigation. Remote controlled vehicle and robot guidance. Satellite positioning and tracking. Shipping. Geographic Information Systems (GIS). Recreation.
Four Primary Functions of GPS Position and coordinates. The distance and direction between any two waypoints, or a position and a waypoint. Travel progress reports. Accurate time measurement.
Position is Based on TimeRadio waves travel at the speedof light. If GPS signal leavessatellite at time “T”… T …and is picked up by the T+3 receiver at time “T + 3.” Then distance between satellite and receiver = “3 times the speed of light”
Pseudo Random Noise Code Time Difference Satellite PRNReceiver PRN
Sources of GPS ErrorStandard Positioning Service (SPS ): Civilian Users Source Amount of Error Satellite clocks: 1.5 to 3.6 meters Orbital errors: < 1 meter Ionosphere: 5.0 to 7.0 meters Troposphere: 0.5 to 0.7 meters Receiver noise: 0.3 to 1.5 meters Multipath: 0.6 to 1.2 meters User error: Up to a kilometer or moreErrors are cumulative
Sources of Signal InterferenceEarth’s Atmosphere Solid Structures Metal Electro-magnetic Fields
A visual example of the GPS constellation in motion with the Earth rotating. Notice how the number of satellites in view from a given point on the Earthssurface, in this example at 45°N, changes with time.
APPLICATIONGPS has become a widely used & useful tool forcommerce, scientific uses , tracking &surveillance.1.Surveying2.map-making3.Navigation4.Cellular telephony5.Tectonics( fault motion measurement inearthquakes)6.Geofencing (vehicle ,person trackingsystems)7. Military