The document discusses Global Positioning Systems (GPS). It describes that GPS uses 24 satellites orbiting Earth to provide location data anywhere on the globe within meters. It operates by measuring the time it takes signals from satellites to reach receivers to determine distance and use triangulation of multiple satellites to calculate a position. GPS has many applications including vehicle navigation, mapping, agriculture, and more.

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