Global Positioning System Presented by: Prateek Rastogi (05IT6013)

What is GPS?  Global Positioning System.  System to Identify the Position on Globe.  Network Of Satellites.

Segments Of GPS  The Space Segment  The Control Segment  The User Segment

The Space Segment  Consists of 24 satellites in 6 orbits.  Each satellites transmits low powered radio signals.  GPS Satellite  Name : NAVSTAR  Altitude : 11,000 miles  Inclination : 55 Deg to the Equator  Weight : 863 Kg(in orbit)  Orbital Period :12 hrs

The Control Segment  A Master Control Station  Unmanned Monitor Stations  Large Ground-antenna Stations

The User Segment  Users-Military and Civilians  GPS Receivers  Decodes the signals from Satellites.  Calculate the distance.

Modes of Operation  Standard Positioning System  Data Transmitted on L1 Frequency  For civil users  Accuracy is degraded  Precise Positioning System  Data Transmitted on L1 and L2 Frequencies  For Military users  Highly Accurate HA=100m VA=156m TA=340ns HA=22m VA=27.7m TA=200ns

Signals from GPS  Coarse/Acquisition- To determine Pseudo range  1023 bit long  1.023Mega-bits per sec  P Code  *10^14 bit long  Mega-bits per sec  Navigation Massage

Working Of GPS

How User Segment calculates the position?

Calculation of Position  Satellites Location  Almanac data  Ephemeris  Time is the essence  Velocity * Time=distance

Determination of Position Trilateration

Sources of Errors  Ionosphere Delays  Troposphere Delays  Clock Error  Multi-path Error  Relativity Error

Correction of Errors  Error Modeling  Mathematical Model  Data Frequency Measurement  Compare the Delays of L1 and L2

Applications  Industry  Agriculture  Mapping & GIS Data Collection  Public safety  Surveying  Telecommunication

Application Contd…..  Military  Intelligence & Target Location  Navigation  Weapon Aiming &Guidance  Transportation  Aviation  Fleet Tracking  Marine

Application Contd…  Science  Archaeology  Atmospheric Science  Environmental  Geology & Geophysics  Oceanography  Wildlife

References   GPS primer “A Student Guide”(Aerospace Corporation)  An Introduction – Global Positioning system S. K. Upadhyaya, G. S. Pettygrove, J.W. Oliveira, B. R. Jahn1  GPS Guide for Beginners(GARMIN Corporation)