GMAT9205 – Fundamentals of Geopositioning Gael Desliens

Table of contents Galileo GNSS Network Clocks Applications

Galileo Galilei Italian astronomer Support the heliocentric view of the universe Faced the Inquistition in 1615 and had to abandon his support

Global Navigation Satellite System (GNSS) Galileo is a GNSS An alternative to other GNSS Inter-operable with GPS and GLONASS Civilian control Accuracy at the meter level Real-time positioning

European GNSS Independence 1st satellite launched in 2005 Should be working in 2014/15

Key figures A constellation of 30 satellites 3 circular Medium Earth Orbits (MEO) Altitude: 23,222 km Inclination: 56° from the equatorial plane

Comparison table GalileoGPSGLONASSCOMPASS Number of satellites 30 (in preparation) (5 operationnal) Orbital height23,222 km20,200 km19,100 km21,150 km Orbital period14.1 h12.0 h11.3 h12.6 h

Network 30 satellites sensor stations 3 control centres 9 Mission Uplink stations 5 TT&C stations (Tracking, Telemetry and Command)

Improvements More satellites Greater inclination to the equatorial plane -> better coverage at high latitudes (useful for Northern Europe) More than 90% probability to be in sight of at least 4 satellites

Technical Satellites equipped with 4 atomic clocks (2 of each): Rubidium clock (6GHz) Hydrogen maser clock (1.4 GHz)

Technical (cont.) Clocks keep time to within a few hundred-millionths of a second per day Accuracy is better than one billionth second in one hour Find your position anywhere on the Earth’s surface within 45 cm

Applications The European Commission set 6 priority domains: Individual handsets and phones Road transport Aviation Maritime transport Agriculture and environment Civil protection and surveillance

Thank you for your attention!

References European Spatial Agency (ESA): European Commission: ex_en.htm ex_en.htm Space-Based Positioning Navigation and Timing: Federal Space Agency: