1. Global Positioning System World’s most advanced communication system

2. Group Members Aishwaria Patil 70703 Hardik Vasa 70712 Gaurav Patil 70711 Prathik Mohan 70726

3. Introduction The Global Positioning System (GPS) is a Global Navigation Satellite System (GNSS) developed by the United States Department of Defense. It uses a constellation of between 24 and 32 Medium Earth Orbit satellites which transmits microwave signals. Its official name in Navstar GPS!!

4. How it all started After Korean Air Lines Flight 007 was shot down in 1983 after straying into the USSR's prohibited airspace. President Ronald Reagan issued a directive making GPS freely available for civilians like us. This is how we use GPS freely today.

5. First navigation system The first satellite navigation system, Transit, used by the United States Navy, was first successfully tested in 1960. Using a constellation of five satellites, it could provide a navigational fix approximately once per hour.

6. Concept of GPS GPS device sends data, GPS device receives data, Precise timing is done, Calculates its position, Again sends data in the next time period. This cycle continuously repeats 25000 times in a minute!

7. Four satellites Actually 3 satellites are enough for one GPS receiver because earth has only 3 dimensions. But the forth satellites is used to correct the error caused in the receiver’s clock.

8. Rotation System

9. Position of your receiver The position of your receiver is the point of intersection of these four spheres. These four spheres are for their functions of height, breath, length and time!

10. GPS clock One of the world’s fastest clock is used in the GPS navigator system. Errors are cause due to a very high intensity of light. Some of the very expensive clocks has the capability to minimize the errors.

11. Division of GPS system 1)Space segmentation: 24 GPS satellites and orbiting vehicles. 2)Control segmentation : The flight paths of the satellites are tracked by US Air Force monitoring stations in the world. 3)User segmentation : Consists of the GPS receivers which the user uses it.

12. Signal frequency All satellites broadcast at the same two frequencies, 1.57542 GHz (L1 signal) and 1.2276 GHz (L2 signal). Higher signal is superimposed on the low frequency signal. And this signal is received by the receiver.

13. GPS in your computer

14. How big is the receiver

15. Disadvantage of GPS

16. Unless it is safe

17. Other disadvantages Costly affair for maintenance Uses vary high power Not applied in rural areas Does not have a very high speed Congestion may occur in the satellites due to over use.

18. Atmospheric effects Inconsistencies of atmospheric conditions affect the speed of the GPS signals as they pass through the Earth's atmosphere (ionosphere ). These effects are smallest when the satellite is directly overhead and become greater for satellites nearer the horizon.

19. Multi path effect GPS signals can also be affected by multipath issues, where the radio signals reflect off surrounding terrain; buildings, canyon walls, hard ground, etc. These delayed signals can cause inaccuracy.

20. Applications Roads Space Aviation Agriculture Marine Rails Geo catching

21. World in your Hand World’s most fastest Communication GPS GPS