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ESA News
http://www.esa.int

9 May 2003

Communication satellites telling us where they are

Communication satellites will eventually be able to tell us where
they are using new on board GNSS (Global Navigation Satellite
System) receivers that are being developed in a project funded by
ESA.
 
The project is nearing completion of its first phase. It focuses on 
designing receivers to pick up the additional L2C (L2 Civilian) and
L5 frequencies that will come from the next generation of GPS
satellites in 2010. The development aims to make multi-frequency
receivers available for both Geo-Stationary and Low-Earth Orbit
satellites. 

The more frequencies available to a receiver the better it is for 
navigation accuracy. The receivers being developed will be used on 
communications satellites and will reduce the dependence on
ground-based stations for position determination. In fact, satellites
should eventually be able to self-determine their position using
GNSS. 

Presently, ground stations track communication satellites and send
radio signals to control centres. Reducing or eradicating the need
for ground stations in locating communications satellites lowers
overall costs and frees up resources.

The new receivers will also contribute to a wide variety of other 
applications, anything from altimeters and scatterometers (devices
used to measure surface parameters) to launchers and Earth
observation. 

The first phase comprised a review of: existing applications and 
technologies, especially important for a more cost-effective 
introduction of the L2C and L5 frequencies; a definition of
requirements for each receiver in order to derive the specifications;
architectural design and definition of the test plan which will lay
the ground work for the next phase. This work is expected to be
completed before the summer.

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