Gps, An Intoduction

Global Positioning System

By Sarath Babu

Global Positioning Systems • GPS is a revolutionary navigation system – 24 satellites orbiting the earth – Provide location within metres or less anywhere on the globe. – Now available in many cars as an option – Created and operated by the US Department of Defense

More about GPS satellites • Constellation of 27 satellites – (24 active + 3 spare) • Orbit 12,600 miles above earth – (10,900 nautical miles) • Satellites in 12 hour orbit • First satellite launched in 1978, 24th became operational in 1994 • Selective availability was removed in May, 2000 – Handheld receivers are now much more accurate

Global Positioning Systems • GPS is a revolutionary navigation system – 24 satellites orbiting the earth – Provide location within metres or less anywhere on the globe. – Now available in many cars as an option – Created and operated by the US Department of Defense

How does GPS work? • Measuring 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 receiver – Information from multiple satellites is used to determine position through ‘triangulation’

How does GPS work?

How does GPS work?

More about GPS receivers • A 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 metres – Vehicle mounted receivers for navigation or agricultural use with accuracy of < 1 metre – Backpack or tripod mounted receivers for surveying use with accuracy of 5 – 10 centimetres

More about GPS receivers • Receivers require clear line-of-sight; thus, they will not work indoors or where tall objects obscure the sky

What’s so cool about GPS? • GPS units – Can be used as a digital compass – Can be used to determine ground speed – Can store landmarks (locations) – Can be used for dynamic routing – Can be used for mapping applications

Applications of GPS • • • • • • • • • •

In-vehicle Navigation (car, boat, airplane) Asset Management Construction Geologic Research & Mining Military Navigation and Operations Mapping & Surveying Precision Agriculture Public Health Public Safety Wireless Communications

Integrating GIS and GPS • Collect a series of latitude and longitude points using GPS receivers – add them into an existing digital map

• Skills in – data collection/creation – GPS reading – observation

• Digital photos

Collecting data • Collect data in the field using GPS – Write down point coordinates and additional data observations - OR – Use tracking function of your unit to store points, lines, or polygons, and write down additional observations

Using the data you collect • Manually enter the coordinates and observations into a table (Excel, etc.) – Save as a .dbf file – Use “Add X,Y” or “Add Event Theme” to create points on your map - OR -

• Use your GPS unit cable to download the data from the unit to your computer

World Scenario • • • •

• • •

Developed by the United States Department of Defense, GPS is officially named NAVSTAR GPS Other satellite navigation systems in use or various states of development include: Beidou – China's regional system that China has proposed to expand into a global system named COMPASS. Galileo – a proposed global system being developed by the European Union, joined by China, Israel, India, Morocco, Saudi Arabia, South Korea, and Ukraine, planned to be operational by 2011–12. GLONASS – Russia's global system which is being restored to full availability in partnership with India. Indian Regional Navigational Satellite System (IRNSS) – India's proposed regional system. QZSS – Japanese proposed regional system, adding better coverage to the Japanese Islands.

Ind ian R egi ona l Na vi gati ona l S atel lite System • The Indian Regional Navigational Satellite System (IRNSS) is an autonomous regional satellite navigation system being developed by Indian Space Research Organisation which would be under total control of Indian government. • Development • The government approved the project in May 2006, with the intention it be implemented within six to seven years. The first satellite of the proposed constellation, developed at a cost of Rupee 1,600 crore (16 billion rupees), is expected to be launched in 2009.

For more information… • Garmin website – http://www.garmin.com/ • Trimble GPS – www.trimble.com/gps • Wikipedia - http://en.wikipedia.org/wiki/Gps • How stuff works – www.howstuffworks.com

Queries …………….

ThAnk yOU