Global Positioning System

1
Global Positioning System

• Vamshi Linga
• Clint Reitsma

2
Outline

• Where it came from
• How it works
• Error Correction
• Galileo and Future Uses

3
Where it Came From

• Funded and Controlled by U.S. DOD
• Originally Designed for the Military
• 1978 First Block of Satellites launched
• 1989 Second Block of Satellites launched
• 1995 Fully Operational
• Korean Flight 007 Crashed President Ronald
  Regan guaranteed all GPS signals would be
  available to the world

4
How it works

• Space Segment
• Control Segment
• User Segment

5
Space Segment

• Five to Eight Satellites visible at any time
• Each satellite transmits data including both
  current location and time
• Signals move at the speed of light

6
Space Segment
7
Control Segment

• Five Control Stations, Master Control at
  Schriever Air Force Base in Colorado
• Monitor satellite health and exact positions
• Makes Corrections

8
Control Segment
9
User Segment

• Consists of Receivers

10
User Segment

• Triangulates by measuring distance using the
  travel time of radio signals
• (Velocity)(Time)Distance
• Very accurate time required (Atomic Clocks on
  Satellites)
• Along with distance, Satellite position is
  required
• Correction of errors

11
User Segment Time

• Star Spangled Banner Example
• Times are very short (0.06 s)
• .001 of second error 200 miles error
• Atomic clocks cost 75,000
• Use a forth Satellite Measurement
• Pseudo Random Code
• Complicated to make unique (not actually random)
• Each satellite has own unique code

12
User Segment Position

• Orbits of Satellites are exact and known by
  receivers (preprogrammed)
• DOD monitors and updates ephemeris errors (orbit
  errors)
• Pseudo Random Code includes navigation message
  with ephemeris error information

13
User Segment
Perfect Example
Real Example
Corrected Example
14
Error Correction

• Differential GPS
• Cooperation of two receivers
• One stationary
• One Mobile
• Stationary Receiver measures timing errors and
  provides correction
• Uses equation backwards
• Uses Known position to calculate time

15
An enabling technology

• Marine navigation
• Air Navigation
• Land navigation
• Surveying
• Military applications

16
Military applications

• Navigation
• Tracking
• Bomb and Missile guidance
• Rescue
• Facility Management

17
Navigation

• Used to reach and destroy vital enemy
  installations
• Provides the accurate positional data

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Tracking

• Track potential targets
• Smart Bombs
• Time space position information

19
Missile Guidance

• Cruise missiles
• Multiple launched Rocket system Vehicles
• Reduces the chances of detection and counter
  Bombardment

20
Rescue and Facility management

• Co-Opted with GIS
• Can help manage and operates large bases which
  cover extensive areas.

21
Galileo Project

• Inter-operable with GPS and GLONASS
• Under civilian control
• Four of the first operational satellites will be
  launched in 2005-2006
• Consists of 30 satellites
• 23616 km altitude above the Earth
• Coverage from 2008

22
Present developments

• Estimated 3.2 billion Euros
• Investment for the first quarter
• Around 1 billion
• India-350 million Euros
• China-300 million Euros
• More than 600 million by ESA

23
Why does Europe and Asia need Galileo

• Civilian uses?
• Geo-political implications?

24
Conclusion

• Website