GNSS & Mapping. GNSS (Global Navigation Satellite System) GIS (Geographic Information System)

GNSS GLOBAL NAVIGATION SATELLITE SYSTEM

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

OUR GNSS (GPS) PRODUCTS Consumer Product High-end Product

Product History Magellan Nav 5200

Magellan Nav 1200

Magellan Meridian Magellan Sport Trck

explorist-gps-family

Triton-gps-family

Since 2010 Explirist x10-gps-family Explirist x10-GIS-family Novatel High-end GNSS -family

History of the GPS Delta rocket launch

Main Segments

Space Techniques There are several satellite techniques Height above earth (km) Satellite types ,500 Remote sensing 1, ,000 Geodetic (GNSS) >36,000 Communication

(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

GPS Satellite Vehicle Weight 2370 pounds Height feet Width feet including wing span Design life—10 years Block IIR satellite vehicle

DELTA6000/7000 Launch Vehicle USA

The GPS Constellation

(2) Ground control segment Master control station AFB, Colorado Five monitor stations Three ground antennas Backup control system

Ground control segment

GPS antennas & receiver/processors Position Velocity Precise timing Used by Aircraft Ground vehicles Ships Individuals User segment

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

The GPS Measurements PSEUDO-RANGES MEASUREMENT CARRIER PHASE MEASUREMENTS

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.

GPS Signal GPS SIGNAL L MHz C/A CodeP CodeNav. Data L MHz C/A CodeNav. DataP Code

Signals around 2015

Satellite TX Model

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.

GPS Signal Structure

L1 Signal

Pseudo Ranging Noise

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

Distance measurements from two satellites limits our location to the intersection of two spheres, which is a circle.

A third measurement narrows our location to just two points.

GPS Position Determination

Good GDOP Poor GDOP

Differential GPS An Introduction

How does it work

Hardware Configuration

GPS RTK System GNSS Base station GNSS ROVER Station

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

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

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 $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

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”

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

Global Coordinate System

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

Shape of the Earth

MAP Datum

The X,Y,Z coordinate system.

Seven-parameter methods

Geoid, Spheroid & Surface ELLIPSOID GEOID

Transverse-secant Cylindrical (Mercator) Projection CM: central meridian AB: standard meridian DE: standard meridian Most New Mexico in Zone 13

CylindricalTransverse CylindricalOblique CylindricalSecant Cylindrical ConicalSecant ConicalPlanarSecant Planar

Sri Lankan Local Grid ( 0, 0 ) North Coordinate East Coordinate Piduruthalagala ( , ) 0, 0

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.

GIS Software ArcGIS GRASS IDRISI ILWIS Quantum GIS MapInfo

Using GIS - Sectors Archeology Aviation Agriculture Defence Telecommunication Survey & Mapping Disaster Management Health Irrigation Construction Navigation Urban Development Etc..

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

Agriculture with GNSS receivers

Application of GPS Technology

Our Product Training

Thanks for your interest in the Global Positioning System… Aruna Weerasinghe(Eng C&G) Retailit(pvt)ltd