The document summarizes the Global Positioning System (GPS), a satellite-based navigation system developed by the U.S. Department of Defense that uses 33 satellites to provide accurate positioning worldwide without subscription fees. GPS determines location by measuring the distance between a receiver and multiple satellites using the satellites' known locations and travel time of radio signals, with potential errors of 50-100 meters that can be reduced to sub-centimeters using dual-frequency receivers. Applications of GPS include aviation, marine navigation, railways, roadways, and electronic gadgets.

1. Global Positioning
System
Finding Location and Applications

2. GPS
“Provide accurate positioning anywhere in the world”
• Satellite based navigation system
• Based on a constellation of about 33 satellites
• Developed by the United States Department
of Defense (DOD)
No subscription fees or setup charges
to use GPS.

3. HOW GPS DETERMINES A LOCATION
• Current locations of GPS satellites
• The distance between Receiver’s Position
and the GPS satellites
• GPS satellites are orbiting the earth at an
altitude of 20,180 miles and orbits are
segmented
The orbits and locations of the satellites are
known in advance

4. …Location
• Distance is the amount of time taken by radio signal
(the GPS signal) to travel from the satellite to the
receiver
• Radio waves travel at the speed of light, i.e. about
186,000 miles per second
distance = speed x time

5. GPS Error
• Sometimes waves get distracted because of
atmosphere or bouncing of waves occur due to
reflecting path
Waves deviation is with in range of 50-100 m
• The solution comes with the Dual Frequency
receivers that provide position in sub-centimeters.

6. Applications
• Aviation
• Marine Timing
• Ballistic / Missile Attack
• Rail ways and Road ways
• NADRA
• Agencies
Electronic gadgets &