GLOBAL POSITIONING SYSTEM

By B.M.G.Prakash Rao

CONTENTS• What is G.P.S?• G.P.S SEGMENTS• HOW G.P.S DETERMINES A LOCATION?• G.P.S SIGNAL ERRORS• CONCLUSION

WHAT IS G.P.S??

• G.P.S stands for GLOBAL POSITIONING SYSTEM• A space based satellite Navigation system• It is developed by U.S.D.O.D

G.P.S SEGMENTS

• It comprises of three segments 1.Space segment 2.Control segment 3.User segment

How G.P.S determines a location??

Things which need to be determined:1. Current location of G.P.S satellites

2. Distance between receiver’s position and G.P.S satellites

Satellite B+

Satellite A+

• Distance measurements from 2 satellites limits our location to the intersection of 2 spheres,which is a Circle…

Satellite A

Satellite B+

+

Satellite C+

• Taking another measurement from a 3rd satellite narrows our position down even further to two points….

• So , by ranging from 3 satellites we can narrow our position to just two points in space

• G.P.S receivers use a 4th satellite to precisely locate our position

G.P.S SIGNAL ERRORS• Different errors can cause a deviation of +/- 50-100 meters from actual G.P.S receiver position which are:

1. Satellite clock: One nano-second of inaccuracy in a satellite clock results in about 30 cm of error…….2. Receiver clock : Any error in receiver clock causes inaccuracy in distance measurement…3. G.P.S Jamming: It limits the effectiveness of the G.P.S signal

CONCLUSION• G.P.S,A Satellite based navigation system can be used to determine the position of any object on earth• It’s application field is very large and

new applications will continue to becreated like GLONASS and GALILEO

as the technology evolves….

THANK YOU