INDEXINTRODUCTIONHISTORYSTRUCTUREAPPLICATIONSWORKING OF GPSBASIC
CONCEPTS OF GPSSYSTEM SEGMENTATIONERROR SOURCESANALYSISTHE
SIGNALCONCLUSION
INTRODUCTION GPS is a revolutionary navigation system24
satellites orbiting the earthProvide location within metres or less
anywhere on the globe.Now available in many cars as an
optionCreated and operated by the US Department of Defense
HISTORYConstellation of 27 satellites(24 active + 3 spare)Orbit
12,600 miles above earth(10,900 nautical miles)Satellites in 12
hour orbitFirst satellite launched in 1978, 24th became operational
in 1994Selective availability was removed in May, 2000Handheld
receivers are now much more accurate
STRUCTURE
Applications of GPSIn-vehicle Navigation (car, boat,
airplane)Asset ManagementConstructionGeologic Research &
MiningMilitary Navigation and OperationsMapping &
SurveyingPrecision AgriculturePublic Health Public SafetyWireless
Communications
WORKING OF GPSMeasuring distance by measuring time
Satellites send coded signals indicating their position in space
and the exact time the signals are being sent Receivers use the
time it takes signal to travel from satellite to receiver to
determine distance from satellite to receiverInformation from
multiple satellites is used to determine position through
triangulation
WORKING OF GPS
BASIC CONCEPTS OF GPSA GPS receiver's job is to locate four or
more satellites, figure out the distance to each, and use this
information to deduce its own location. Hand-held receivers for
recreational use with accuracy of 10-15 metresVehicle mounted
receivers for navigation or agricultural use with accuracy of <
1 metreBackpack or tripod mounted receivers for surveying use with
accuracy of 5 10 centimetres
BASIC CONCEPTS OF GPSReceivers require clear line-of-sight;
thus, they will not work indoors or where tall objects obscure the
sky
The total GPS configuration is comprised of three distinct
segments (1) The space segment-Satellites orbiting the Earth (2)
The control segment-Stations positioned on the Earths equator to
control the satellites. (3) The user segment Anybody that receives
and uses the GPS signal.SYSTEM SEGMENTATION
ERROR SOURCESIonospheric and atmospheric delaysSatellite and
Receiver clock errorsDilution of precisionMultipathBlenders
ANALYSISNumber of visible satellitesPosition dilution of
precisionSatellite elevationsMultipathDistance between space
station and rover receivers
A GPS Signal contains three different bits of information
(1).Pseudo random code
(2).Ephemeris data
(3).Almanac dataTHE SIGNAL
GPS was originally designed for military use at any time,
anywhere on the surface of the earth. The civilians may also use
GPS to marine navigation, car navigation and surveying.CON
CLUSION
