Group presentation done on GPS technology it covers 1.Introduction -History,Background 2.What is GPS - Technology, infrastructure 3.How GPS Works - Theory,Mathematical explanation 4.Applications of GPS 5.Drawbacks of GPS 6.Future Development #References are added to the note section of the slides.

1. Global Positioning System
(GPS)
WDN Presentation
CSN - SLIIT
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2. Team Members
1. Sachin Thishnika
2. Kusal Indika
3. Vidusha Rathnayaka
4. Nadeendra Yashaswin
5. Janaka Poddalgoda (Absent)
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3. Content
1. Introduction
2. What is GPS ?
3. How GPS Works
4. Applications of GPS
5. Drawbacks of GPS
6. Future Development
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4. Introduction
Navigation in early days
 North Star
 Compass
 LORAN & Decca Navigator
GPS project
 Developed under Department of Defense
GPS is not alone
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5. What is GPS ?
Global Navigation Satellite System (GNSS)
Provide
 Position
 Timing
 Navigation
Three segments
 Space
 Control
 User
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6. What is GPS ? Cont.
Space segment
 24 satellites
 At least six satellites on LOS
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7. What is GPS ? Cont.
Control Segment
 Operate by US Air force
 Consist of
•
•
•
•
Master Control Segment (MCS)
Alternative MCS
Dedicated ground antennas
Monitoring stations
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8. What is GPS ? Cont.
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9. What is GPS ? Cont.
User segment
 Consist of GPS receivers
 Calculate location using GPS signals
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10. How GPS Works
Satellite emit two signals




L1 (1575.42 MHz) UHF band – civil use
L2 – (1227.60 MHz) - Military use
Power 50w
CDMA
GPS signal
 Pseudo random code
 Almanac data
 Ephemeris data
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11. How GPS Works
• Beacon –Radio Signal
• Travel time(t)=Sync of receive time – Satellite Time
•
d=C*t
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12. How GPS Works Cont.
Triangulating
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13. Applications of GPS
GPS is an essential element of the global
information infrastructure
It’s
 Free
 Open
 Dependable
“New uses of GPS are invented every day and
are limited only by the human imagination.”
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14. Applications of GPS cont.
Aviation
 Cost effective solution
 Increase the safety and efficiency
 Three-dimensional positioning
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15. Applications of GPS cont.
Space
 Navigation solutions
 Altitude solutions
 Timing solutions & etc.
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16. Applications of GPS cont.
Survey & mapping
 Accuracy
 Reliability
 Interoperability
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17. Applications of GPS cont.
Differential GPS
 10 meters to 10 centimeters
 Base station in known location
 Real-time DGPS
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18. Drawbacks of GPS
Signal multipath
Atmospheric effect
No GPS signals in
 Indoor
 Under water
 Under ground
Attacks
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19. Future Development
GPS III




Enhanced signal reliability & accuracy
L1C signal
L2C signal
Schedule to launch in 2015
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20. Future Development Cont.
No Selective Availability (SA)
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21. Future Development Cont.
L5 “safety-of-life” signal
 Two times powerful as L2C
 Focus on aviation & transportation
 Resistant to jamming & interference
High gain directional antenna
 100 times more powerful than wide angle
antenna
 M-coded military signal
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22. Future Development Cont.
Cross platform receivers
 More accurate
 Fast convergence
GPS & GLONASS satellites
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23. GPS Technology
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24. GPS Technology
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