The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite systems (GNSS) that provides geolocation and time information to a GPS receiver anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites. Obstacles such as mountains and buildings block the relatively weak GPS signals.

1. Global Positioning System
(GPS)
Manju
M.Phil.(Geography)
NET,NFSC
Maharshi Dayanand University (Rohtak)

2. What is GPS?

3. • The Global Positioning System (GPS), originally Navstar GPS, is a
satellite-based radionavigation system owned by the United States
government and operated by the United States Space Force.
• It is one of the global navigation satellite systems (GNSS) that
provides geolocation and time information to a GPS receiver
anywhere on or near the Earth where there is an unobstructed line of
sight to four or more GPS satellites.
• Obstacles such as mountains and buildings block the relatively weak
GPS signals.

4. GPS:-
• Global Positioning System
• Network of 24 satellites (with spares)
• Developed by Department of Defense
• Operational 24 hours/day
• Available worldwide
• Land, sea and air
• Works in all weather conditions
• It is FREE!!

5. Characteristics of GPS satellite?
• Orbital Height – 20200 km
• Period - 12 hours
• Frequencies - 1575 MHz
• Navigation Data – 1228 MHz
• Availability - continually
• Accuracy - 15 km
• Satellite constellation – 21-24
• Geometry – Repeating
• Satellite Clocks – Rubidium Cesium Atomic

6. History of GPS?
• The GPS project was launched in the United States in 1973 to overcome the limitations of
previous navigation systems, integrating ideas from several predecessors, including classified
engineering design studies from the 1960s. The U.S. Department of Defense developed the
system, which originally used 24 satellites. It was initially developed for use by the United
States military and became fully operational in 1995. Civilian use was allowed from the
1980s. Roger L. Easton of the Naval Research Laboratory, Ivan A. Getting of The Aerospace
Corporation, and Bradford Parkinson of the Applied Physics Laboratory are credited with
inventing it. The work of Gladys West is credited as instrumental in the development of
computational techniques for detecting satellite positions with the precision needed for GPS.
• The design of GPS is based partly on similar ground-based radio-navigation systems, such as
LORAN and the Decca Navigator, developed in the early 1940s.
• In 1955, Friedwardt Winterberg proposed a test of general relativity – detecting time slowing
in a strong gravitational field using accurate atomic clocks placed in orbit inside artificial
satellites. Special and general relativity predict that the clocks on the GPS satellites would be
seen by the Earth's observers to run 38 microseconds faster per day than the clocks on the
Earth. The GPS calculated positions would quickly drift into error, accumulating to 10
kilometers per day (6 mi/d). This was corrected for in the design of GPS.

7. Segments of GPS
I. Space Segment – Satellite Constellation.
II. Control Segment– Monitoring Stations and Ground Antennas.
III. User Segment – Receivers.

8. Segments of GPS?

9. Space Segment – Satellite Constellation

10. Control Segment-Monitoring Stations and Ground Antennas

11. User Segment
GPS receiver equipment:-
Some examples are: Our
airplane receivers,
handheld devices (mobile
phone, iPads etc.)

12. Uses of GPS: -
Locating
Tracking
Navigating
Mapping
Timing

13. Using GPS continued:-
• Survey disaster areas, Map movement of
environmental disasters (Oil spills, wild fires, floods,
etc)
• Mapping fallout shelters, sidewalks, streets, trees,
trails, etc.
• Measuring the growth or decline of mountains

14. Conclusion
❑ GPS is an organization of satellites that ceaselessly send coded
data, which makes it conceivable to decisively distinguish areas on
earth by estimating distance from the satellites.
❑GPS despite the fact that was created for military purposes,
however the quantity of regular citizen clients of GPS effectively well
far surpasses than number of possible military .
❑As examined in past subject, its application field is huge and new
applications will keep on being made as the innovation advances.

15. Reference:-
• Sharma, R.(2010). Air Photo Interpretation Remote Sensing and
Geographical Information System. Udaipur: Himanshu Publication.
• Chaunihal, D.(2012). Remote Sensing & Geographical Information
System. Allahabad: Sharda Pushtak, Bhawan,

16. THANK YOU