By :- Ankit Siddharth

1. Global Positioning System (GPS)
Submitted By:-
ANKIT SIDDHARTH
B.Sc. 1st Year

4. What Is GPS?
Satellite based navigation
system.
Based on a constellation of
about 24 satellites
Developed by United States,
Department of Defence (DOD)

5. What Is GPS?
Can provide accurate
positioning 24 hours a day,
anywhere in the world.
No subscription fees or setup
charges to use GPS.
GPS satellites also called
NAVSTAR, the official U. S.
DOD name for GPS.

6. Structure
Space Segment
Control Segment
User Segment

7. How GPS Determines A Location

8. How GPS Determines A Location
Things which need to be determined:
Current Locations of GPS Satellites
The Distance Between Receiver’s Position and The GPS Satellites

9. Current Locations of GPS Satellites
GPS Satellites are orbiting the earth at an altitude of 11,000 Miles
The orbits, and the locations of the satellites, are known in
advance.
GPS receivers store this orbit information for all of the GPS
satellites in an ALMANAC*.
*THE ALMANAC IS A FILE WHICH CONTAINS POSITIONAL INFORMATION FOR ALL OF THE GPS
SATELLITES.

10. All 24 satellites are divided into
6 parts.
There are 4 satellites in each
part.
A definite orbit is defined for
each part.
Each of these 3,000- to 4,000-
pound solar-powered satellites.

11. DISTANCE BETWEEM RECEIVER’S
POSITION & THE GPS SATELLITES
•By measuring 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.
•The distance from the satellite to the receiver can be
determined by the formula “distance = speed × time”.

12. GPS ERROR BUDGET
Different errors can cause a deviation of +/- 50 – 100
meters from the actual GPS receiver position which are :
ATMOSPHERIC CONDITIONS:
•Speed of GPS signal is affected by ionosphere and
troposphere.
•Which cause a deviation of 0 to 30 m. from the actual
position of receiver.

13. EPHEMERIS ERRORS:
•The predicted changes in the orbit of a satellite.
•Which cause a deviation of 0 to 5 m. from the actual
position of receiver.
CLOCK DRIFT:
•Due to different code generations in satellite and
receiver simultaneously.
•Which cause a deviation of 0 to 1.5 m. from the actual
position of receiver.

14. MULTIPATH:
•Bouncing of a GPS signal due to a reflecting surface
before reaching to receiver antenna.
•Which cause a deviation of 0 to 1 m. from the actual
position of receiver.

15. MEASURING GPS ACCURACY
The geometry of the constellation is evaluated by
Dilution Of Precision, DOP.
DOP

16. Applications
of GPS
AVIATION
MARINE
AGRICULTURE
TIMING
RAILWAYS
SPACE
ROADWAYS
DISASTER
RELIEF

17. Name Launch Date
NAVSTAR 64 (USA 206) August 17, 2009
NAVSTAR 63 (USA 203) March 24, 2009
NAVSTAR 62 (USA 201) March 15, 2008
NAVSTAR 61 (USA 199) December 20, 2007
NAVSTAR 60 (USA 196) October 17, 2007
NAVSTAR 59 (USA 192) November 17, 2006
NAVSTAR 58 (USA 190) September 25, 2006
NAVSTAR 57 (USA 183) September 26, 2006
NAVSTAR 56 (USA 180) November 6, 2004
NAVSTAR 55 (USA 178) June 23, 2004
NAVSTAR 54 (USA 177) March 20, 2004
NAVSTAR 53 (USA 175) December 21, 2003
NAVSTAR 52 (USA 168) March 31, 2003
GPSOperationalSatellites

18. GPSOperationalSatellites
Name Launch Date
NAVSTAR 51 (USA 166) January 29, 2003
NAVSTAR 50 (USA 156) January 30, 2001
NAVSTAR 49 (USA 154) November 10, 2000
NAVSTAR 48 (USA 151) July 16, 2000
NAVSTAR 47 (USA 150) May 11, 2000
NAVSTAR 46 (USA 145) October 7, 1999
NAVSTAR 44 (USA 134) November 6, 1997
NAVSTAR 43 (USA 132) July 23, 1997
NAVSTAR 39 (USA 128) September 12, 1996
NAVSTAR 38 (USA 126) July 16, 1996
NAVSTAR 37 (USA 117) March 28, 1996
NAVSTAR 36 (USA 100) March 10, 1994

19. THANK YOU