Gps

Global Positioning System

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

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.

Indian Regional Navigational Satellite 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