Introduction to global position system
Download as PPTX, PDF7 likes1,734 views
The document provides an overview of the Global Positioning System (GPS) in 3 segments: the space segment consists of 24+ satellites in orbit that broadcast timing and position data; the control segment includes 5 monitoring stations that track satellites and upload corrections; the user segment comprises over 3 billion GPS receivers used for navigation, mapping, and other purposes by both military and civilian users. GPS determines position by precisely measuring the time it takes signals from at least 4 satellites to reach a receiver.
Introduction to global position system
- 1. Introduction to Global Position System
- 2. Slide 2 What is GPS Space Segment Control Segment User Segment The Global Positioning System (GPS) is a Constellation of Earth-Orbiting Satellites Maintained by the United States Government for the Purpose of Defining Geographic Positions On and Above the Surface of the Earth. It consists of Three Segments:
- 4. Control Segment Space Segment User Segment Three Segments of the GPS Monitor Stations Ground Antennas Master Station
- 5. GPS Satellite Vehicle Four atomic clocks Three nickel-cadmium batteries Two solar panels Battery charging Power generation 1136 watts S band antenna—satellite control 12 element L band antenna—user communication Block IIF satellite vehicle (fourth generation)
- 6. Slide 6 Space Segment Description Very high orbit 20,200 km – 1 revolution in approximately 12 hrs For accuracy Survivability Coverage 24+ satellites 6 planes with 55° Inclination Each plane has 4 or 5 satellites Broadcasting position and time information on 2 frequencies Constellation has Spares
- 7. Slide 7 Control Segment Master Control Station Monitor Station Ground Antenna Colorado Springs Hawaii Ascension Islands Diego Garcia Kwajalein Monitor and Control
- 8. Slide 8 Control Segment (5) Monitor Stations • Correct Orbit and clock errors • Create new navigation message • Observe ephemeris and clock Falcon AFB Upload Station
- 9. Slide 9 User Segment Over $19 Billion invested by DoD Dual Use System Since 1985 (civil & military) Civilian community was quick to take advantage of the system Hundreds of receivers on the market 3 billion in sales, double in 2 years 95% of current users DoD/DoT Executive Board sets GPS policy PLGR
- 10. Military. Search and rescue. Disaster relief. Surveying. Marine, aeronautical and terrestrial navigation. Remote controlled vehicle and robot guidance. Satellite positioning and tracking. Shipping. Geographic Information Systems (GIS). Recreation. User Segment
- 11. ESSC 541-542 Lecture 4.14.0511 How the system works Space Segment 24+ Satellites The Current Ephemeris is Transmitted to Users Monitor Stations Diego Garcia Ascension Island Kwajalein Hawaii Colorado Springs GPS Control Colorado Springs End User
- 12. Slide 12 Distance Measuring The whole system revolves around time!!! Distance = Rate x Time • Rate = 186,000 miles per second (Speed of Light) • Time = time it takes signal to travel from the SV to GPS receiver
- 13. Signal From One Satellite The receiver is somewhere on this sphere.
- 14. Signals From Two Satellites
- 15. Three Satellites (2D Positioning)
- 16. Three Dimensional (3D) Positioning
- 17. Slide 17 Triangulation Satellite 1 Satellite 2 Satellite 3 Satellite 4
- 18. Slide 18 Measuring Travel Time SV Clocks 2 Cesium & 2 Rubidium in each SV $100,000-$500,000 each Receiver Clocks Clocks similar to quartz watch Always an error between satellite and receiver clocks ( t) Require 4 satellites to solve for x, y, z, and t
- 19. Slide 19 Common Problems - Errors GPS Antenna Hard Surface Satellite
- 20. Slide 20 GPS Multipath Errors Effects of Multipath on the GPS Signal •Avoid Reflective Surfaces •Use A Ground Plane Antenna •Use Multipath Rejection Receiver GPS Antenna Hard Surface Satellite