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
Since 2010 Explirist x10-gps-family Explirist x10-GIS-family
Novatel High-end GNSS -family
Slide 12
History of the GPS Delta rocket launch
Slide 13
Main Segments
Slide 14
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
Slide 15
(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
(2) Ground control segment Master control station AFB, Colorado
Five monitor stations Three ground antennas Backup control
system
Slide 21
Ground control segment
Slide 22
GPS antennas & receiver/processors Position Velocity
Precise timing Used by Aircraft Ground vehicles Ships Individuals
User segment
Slide 23
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
Slide 24
The GPS Measurements PSEUDO-RANGES MEASUREMENT CARRIER PHASE
MEASUREMENTS
Slide 25
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.
Slide 26
GPS Signal GPS SIGNAL L1 1575.42 MHz C/A CodeP CodeNav. Data L2
1227.6 MHz C/A CodeNav. DataP Code
Slide 27
Signals around 2015
Slide 28
Satellite TX Model
Slide 29
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.
Slide 30
GPS Signal Structure
Slide 31
L1 Signal
Slide 32
Pseudo Ranging Noise
Slide 33
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
Slide 34
Distance measurements from two satellites limits our location
to the intersection of two spheres, which is a circle.
Slide 35
A third measurement narrows our location to just two
points.
Slide 36
GPS Position Determination
Slide 37
Slide 38
Good GDOP Poor GDOP
Slide 39
Differential GPS An Introduction
Slide 40
How does it work
Slide 41
Hardware Configuration
Slide 42
GPS RTK System GNSS Base station GNSS ROVER Station
Slide 43
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
Slide 44
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
Slide 45
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 5-121-34-101
ApplicationScoutingMapping / Guidance Elevation mapping, Precision
row operations
Slide 46
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
Slide 47
Globe Spherical Earths surface -radius 6371 km Meridians (lines
of longitude) - passing through Greenwich, England as prime
meridian or 0 longitude. Parallels (lines of latitude) - using
equator as 0 latitude. degrees-minutes-seconds (DMS), decimal
degrees (DD) True direction, shape, distance, and area
Slide 48
Global Coordinate System
Slide 49
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
Slide 50
Shape of the Earth
Slide 51
MAP Datum
Slide 52
The X,Y,Z coordinate system.
Slide 53
Seven-parameter methods
Slide 54
Geoid, Spheroid & Surface ELLIPSOID GEOID
Slide 55
Transverse-secant Cylindrical (Mercator) Projection CM: central
meridian AB: standard meridian DE: standard meridian -105 -108 -102
Most New Mexico in Zone 13
Sri Lankan Local Grid ( 0, 0 ) North Coordinate East Coordinate
Piduruthalagala ( 200000, 200000 ) 0, 0
Slide 59
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.
Using GIS - Sectors Archeology Aviation Agriculture Defence
Telecommunication Survey & Mapping Disaster Management Health
Irrigation Construction Navigation Urban Development Etc..
Slide 62
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
Slide 63
Agriculture with GNSS receivers
Slide 64
Application of GPS Technology
Slide 65
Our Product Training
Slide 66
Thanks for your interest in the Global Positioning System Aruna
Weerasinghe(Eng C&G) Retailit(pvt)ltd