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GNSS & Mapping. GNSS (Global Navigation Satellite System) GIS (Geographic Information System)
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GNSS GLOBAL NAVIGATION SATELLITE SYSTEM
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GNSS GPS GLONASS GALILEO BEIDOU IRNSS GPS (USA)- Global Positioning System GLONASS (Russia)- Global Navigation Satellite System GALILEO (Europe)- European Satellite Navigation system BEIDOU (China)- Beidou Satellite Navigation and Positioning System IRNSS (India)- Indian Regional Navigational Satellite System
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OUR GNSS (GPS) PRODUCTS Consumer Product High-end Product
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Product History 1993-1995 Magellan Nav 5200
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1995-1998
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1998-2002 Magellan Nav 1200
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2002-2004 Magellan Meridian Magellan Sport Trck
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2004-2008 explorist-gps-family
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2008-2010 Triton-gps-family
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Since 2010 Explirist x10-gps-family Explirist x10-GIS-family Novatel High-end GNSS -family
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History of the GPS Delta rocket launch
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Main Segments
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Space Techniques There are several satellite techniques Height above earth (km) Satellite types 150 - 1,500 Remote sensing 1,500 - 20,000 Geodetic (GNSS) >36,000 Communication
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(1) Space segment 24 satellite vehicles Six orbital planes – Inclined 55 o with respect to equator – Orbits separated by 60 o 20,200 km elevation above Earth Orbital period of 11 hr 55 min Five to eight satellites visible from any point on Earth Block I Satellite Vehicle
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GPS Satellite Vehicle Weight 2370 pounds Height 16.25 feet Width 38.025 feet including wing span Design life—10 years Block IIR satellite vehicle
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DELTA6000/7000 Launch Vehicle USA
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The GPS Constellation
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(2) Ground control segment Master control station AFB, Colorado Five monitor stations Three ground antennas Backup control system
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Ground control segment
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GPS antennas & receiver/processors Position Velocity Precise timing Used by Aircraft Ground vehicles Ships Individuals User segment
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How does GPS work? Satellite ranging – Satellite locations – Satellite to user distance – Need four satellites to determine position Distance measurement – Radio signal traveling at speed of light – Measure time from satellite to user
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The GPS Measurements PSEUDO-RANGES MEASUREMENT CARRIER PHASE MEASUREMENTS
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PSEUDO-RANGES MEASUREMENT Distance to a satellite is determined by measuring how long a radio signal takes to reach us from that satellite. To make the measurement we assume that both the satellite and our receiver are generating the same pseudo-random codes at exactly the same time. By comparing how late the satellite's pseudo-random code appears compared to our receiver's code, we determine how long it took to reach us. Multiply that travel time by the speed of light and you've got distance.
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GPS Signal GPS SIGNAL L1 1575.42 MHz C/A CodeP CodeNav. Data L2 1227.6 MHz C/A CodeNav. DataP Code
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Signals around 2015
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Satellite TX Model
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PRN - Calculating Position Speed of GPS signal = 3 x 10 8 ms -1 Distance from satellite = Speed x Time taken Distance = 3 x 10 8 ms -1 x t ‘t’ must be found.
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GPS Signal Structure
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L1 Signal
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Pseudo Ranging Noise
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The distance (x) from one satellite tells us we're located somewhere on the surface of an imaginary sphere centered on that satellite with a radius of x. x miles
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Distance measurements from two satellites limits our location to the intersection of two spheres, which is a circle.
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A third measurement narrows our location to just two points.
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GPS Position Determination
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Good GDOP Poor GDOP
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Differential GPS An Introduction
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How does it work
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Hardware Configuration
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GPS RTK System GNSS Base station GNSS ROVER Station
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GPS Error Sources – Ionospheric group delays – Tropospheric refraction delays – Ephemeris errors (e) – Satellite clock errors (d) – Receiver clock errors – Multipath signal – Satellite and receiver noises
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Application of GPS Technology Private and recreation – Traveling by car – Hiking, climbing, biking – Vehicle control Mapping, survey, geology English Channel Tunnel Agriculture Aviation – General and commercial – Spacecraft Maritime
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45 of 10 Agriculture GPS Type Comparison PerformanceLowMiddleHighVery High TechnologyLow cost DGPS DGPSTwo Frequency DGPS Real Time Kinematic RTK GPS Price $100 to 600 $600 to $3,000 $1,500 to 10000 $25,000 to $42,000 Differential Source WAASWAAS + C.G. Beacon + SBAS WAAS + C. G. Beacon + HP SBAS User Base Station HP SBAS Static Accuracy 5’-12’1’-3’4”-10”1” ApplicationScoutingMapping / Guidance Elevation mapping, Precision row operations
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GIS (Geographic Information System) “A system for capturing, storing, checking, integrating, manipulating, analysing and displaying data which are spatially referenced to the Earth. This is normally considered to involve a spatially referenced computer database and appropriate applications software”
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Globe Spherical Earth’s surface -radius 6371 km Meridians (lines of longitude) - passing through Greenwich, England as prime meridian or 0º longitude. Parallels (lines of latitude) - using equator as 0º latitude. degrees-minutes-seconds (DMS), decimal degrees (DD) True direction, shape, distance, and area
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Global Coordinate System
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Modeling The Earth Shape of the Earth (Equi-potential surface) Geoid – Undulated shape Modeled as a spheroid World standard spheroid – WGS84 Sri Lanka does not coincide with WGS84 Spheroid for Sri Lanka – Everest 1830 WGS84Everest
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Shape of the Earth
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MAP Datum
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The X,Y,Z coordinate system.
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Seven-parameter methods
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Geoid, Spheroid & Surface ELLIPSOID GEOID
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Transverse-secant Cylindrical (Mercator) Projection CM: central meridian AB: standard meridian DE: standard meridian -105 -108 -102 Most New Mexico in Zone 13
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CylindricalTransverse CylindricalOblique CylindricalSecant Cylindrical ConicalSecant ConicalPlanarSecant Planar
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Sri Lankan Local Grid ( 0, 0 ) North Coordinate East Coordinate Piduruthalagala ( 200000, 200000 ) 0, 0
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Geographic Latitude/Longitude on a flat surface (WGS 84 datum) Scale, distance, area, and shape are all distorted with the distortion increasing toward the poles.
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GIS Software ArcGIS GRASS IDRISI ILWIS Quantum GIS MapInfo
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Using GIS - Sectors Archeology Aviation Agriculture Defence Telecommunication Survey & Mapping Disaster Management Health Irrigation Construction Navigation Urban Development Etc..
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Map Scale Scale refers to the relationship or ratio between a distance on a map and the distance on the earth it represents. Maps should display accurate distances and locations, and should be in a convenient and usable size. Map scales can be expressed as - representative fraction or ration: 1:100,000 or 1/100,000 - graphical scale: - verbal-style scale: 1 inch in map equal to 2000 feet on the ground or 1 inch = 2000 feet
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Agriculture with GNSS receivers
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Application of GPS Technology
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Our Product Training
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Thanks for your interest in the Global Positioning System… Aruna Weerasinghe(Eng C&G) Retailit(pvt)ltd
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