How gps works

How Does GPS How Does GPS Work?Work?

What does GPS stand for ?What does GPS stand for ?&&

What does GIS stand for ?What does GIS stand for ?

GGlobal lobal PPositioning ositioning SSystemystem

&&

GGeographic eographic IInformation nformation SSystemystem

What is GPS ?What is GPS ? Network of 24 satellitesNetwork of 24 satellites Operational 24 hours/dayOperational 24 hours/day Available worldwideAvailable worldwide Land, sea and airLand, sea and air It is FREE!!It is FREE!!

Software program and databaseSoftware program and database storing, analyzing and displaying storing, analyzing and displaying

informationinformation

What is GIS ?What is GIS ?

Satellite ConstellationSatellite Constellation

GPS SatelliteGPS Satellite Weighs about 1Weighs about 1 TonTon

orbit 20orbit 20000000 km km above the Earthabove the Earth

Travels 3000 m/sTravels 3000 m/s

Circle the Earth twice Circle the Earth twice a daya day

How Does GPS Work?How Does GPS Work?

How it worksHow it works

Satellite circles the Earth and transmits Satellite circles the Earth and transmits signalsignal

Signal contains time it was sent and its Signal contains time it was sent and its locationlocation

Signal travels at the speed of lightSignal travels at the speed of light

The time differenceThe time difference

it’s possible to calculate other informationit’s possible to calculate other information

Trilateration Trilateration

Process of measuring the distance Process of measuring the distance from at least three satellites from at least three satellites

Three satellites calculate 2D position Three satellites calculate 2D position (Latitude and Longitude)(Latitude and Longitude)

Four or more satellites calculate 3D Four or more satellites calculate 3D position (Latitude, Longitude, and position (Latitude, Longitude, and Altitude)Altitude)

ExampleExample

XX

YY

ZZ

3-D Trilateration3-D Trilateration1 Satellite 2 Satellites

3 Satellites

Now for the Now for the

fun part!fun part!

Example

Map Page

Compass Page

Trip Page Satellites Page

Thank You For ListeningThank You For Listening