Capturing data and use of GPS Capturing data GIS GPS Paper maps - PDF document

Capturing data and use of GPS

Capturing data GIS GPS Paper maps Coordinates Satellite images

What is a GPS? Global Positioning System A network of satellites that continuosly transmit informations Making possible to identify locations

How works a GPS

Possible sources of errors • Getting signals from 3-4 satellites GPS calculates its position by triangulation • The number of satellites “in view” depends on the time of day and where you are on earth • Unfortunately satellites are often hidden behind mountains, buildings and even forests • The more satellites that can be tracked the greater the chance of an accurate position fix.

Sources of Errors in GPS • Poor signal reception can be cause by – Blockage by buildings, hills, trees and even your own body – Weak batteries – Interference from other electronic equipment in use nearby

This is your GPS

Pages featured in your GPS

Menu button

Acquiring satellites

Acquiring satellites Latitude Horizontal position Longitude Latitude Altitude Longitude

Acquiring satellites Horizon 45° above the Horizon Overhead

Defining your position

Defining your position the average position

GPS use • The GPS gives you the possibility to define your position with coordinates: – Latitude – Longitude – Altitude

The two coordinates together do the earth’s grid Latitude and Longitude are expressed in: Degrees, Minutes, Seconds Long. W 73° 59’ 15 ’’

Latitude, longitude, decimal degrees • Latitude and Longitude can be also expressed in decimal degree Decimal degrees = Degrees + (Minutes/60) + (Seconds/3600) 73° 59´15 ´´ = 73,9875

Basics Latitude: 90 North 1 Equator 90 South Longitude: 180 West Null Meridian 180 East

To allow to pass from a curved Earth to a flat map

Mercator projection

Advantages of UTM • Square grid allows easy measurement • Cartesian coordinate system • Metric unit • No negative numbers

Connect your GPS with your computer using appropriate application, extensions or softwares