1. Global Positioning System

2. 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

3. 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

4. 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’

5. How does GPS work?

6. How does GPS work?

7. 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

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

9. 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

10. 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

13. 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

14. 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

15. 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

16. 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.

17. 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.

18. 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

19. Queries …………….
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20. ThAnk yOU