Seminar presentation on Global Positioning System (GPS)

1. GLOBAL POSITIONING
SYSTEM
NAME-ANUJ PARMAR
ROLL NO.-16275

2. HISTORY
• NAVIGATING BY STARS, MOST WIDELY USED FOR CENTURIES
• GPS WAS ORIGINALLY CREATED AND REALIZED BY U.S DEPARTMENT OF DEFENSE AND
WAS ORIGINALLY RUN WITH 24 SATELLITES.
• IT BECAME FULLY OPERATIONAL IN 1995.

3. WHAT IS GPS
• gps stands for global positioning system.
• GPS is a satellite navigation system used to determine the ground position of an object.
• Maintained by u.s government and accessible by anyone with gps receiver.

4. OVERVIEW
• official name ; navigational satellite timing and ranging global positioning system.
• Consists of 30+ satellites in medium earth orbit.
• Made up of satellites working in harmony are known as satellite constellation.
• main;ly used for navigation, map making and surveying

5. STRUCTURE
• GPS consists of 3 segments ;
1. space segment
2. Control system
3. User segment

7. HOW GPS DETERMINES LOCATION
• things which need to be determined;
1. Current location of GPS satellites
2. Distance between receiver’s position and satellites.

8. CURRENT LOCATION OF SATELLITES
• GPS satellites are orbiting the earth at an altitude of 11,000 miles.
• The orbits and location of satellites are known in advance.
• GPS receivers store this orbit information for all of GPS satellites in almanac.

9. DISTANCE BETWEEN RECEIVER’S POSITION AND
SATELLITES
• By measuring the amount of time taken by radio signal to travel from satellite to receiver.
• Radio waves travel almost at the speed of light.
• The distance from satellite to receiver can be determined by formula-distance=speed*time

10. GPS ERROR
Different errors can cause a deviation of +/- 50 to 100 meters from actual GPS receiver position.
1. Atmospheric conditions
• Speed of GPS signal is affected by ionosphere and troposphere.
• Which cause a deviation of 30m from actual position of receiver.

11. EPHEMERIS ERRORS
• The predicted changes in the orbit of satellite.
• Which cause a deviation of 5m from actual position.

12. MULTIPATH
• Bouncing of GPS signal due to reflecting surfaces before reaching the receiver antenna.
• Which causes a deviation of 1m from actual position.

13. GEOMETRIC DILUTION OF PRECISION
• Satellite geometry can affect the accuracy of GPS positioning.
• Measure of quality of satellite configuration.
• Able to modify other GPS errors.
• Quality can be determined in terms of position dilution of precision.

14. POSITION DILUTION OF PRECISION
• Position dilution of precision are of 2 types:
1. Horizontal dilution of precision
2. Vertical dilution of precision
• A low DOP indicates higher probability of accuracy.
• A high DOP indicates lower probability of accuracy.
• Also known as time dilution of precision.

15. APPLICATIONS
• Surveying: surveyors use location to make maps and determine property boundaries.
• Can track movements of object for ex. Locating vehicle.

17. APPLICATIONS
• GPS satellite based navigation system is important tool for military.
• GPS is widely used in aviation.
• For example; you need to radio helicopter pilot the coordinates of your position so pilot can pick
you.
• To determine distance between 2 different points

18. THANK YOU