European GPS overlay infrastructure
From INVESaTWIKI
Technological trends - EGNOS and Galileo differentiators and benefits
Satellite navigation applications are currently
based on GPS performances, and great
technological effort is spent to integrate
satellite-derived information with a number of
other techniques, in order to reach better
positioning precision with improved reliability.
This scenario will significantly change in the
short-term future. EGNOS, the European
regional augmentation of GPS, will as from
2005 start to provide its services.The global
satellite navigation infrastructure will then
double with the advent of Galileo, with initial
service in the coming years.The availability of
two or more constellations, more than
doubling the total number of available
satellites in the sky, will enhance the quality of
the services and increase the number of
potential users and applications. (see Figure 1)
Galileo’s specific characteristics will bring
significant enhancements. Firstly, for urban
areas or indoor applications, the design of
Galileo signals will improve the availability of
the service (broadcast of dataless ranging
channels, in addition to the classical pseudo
random ranging codes). Secondly, the high-end
professional market will also benefit from
Galileo signals characteristics.Three carriers
phase measurements will be essential for the
development of specific “TCAR” algorithms,
leading to centimetre accuracy over large
regions.
With its full complement of satellites, GALILEO will allow positions to be determined more accurately even in high-rise cities, where buildings obscure signals from today's satellites. Galileo will also offer several signal enhancements making the signal more easy to track and acquire and more resistant against interference and reflections.[1]
Simulations demonstrate that availability of
positioning services in urban areas where
“canyons” occur (satellite visibility obstruction
by high buildings and skyscrapers) is increased
typically, from 50% to above 95% using both
Galileo and GPS.
Galileo is under civil control and has been
designed under civil requirements. It is
operated in a transparent way, allowing for full
service certification.
The need for service guarantee for safety-oflife
and commercial applications has been
taken into account in the design of the
systems. Legal implications of service level
commitment are driving the Galileo system
implementation. Accountability requirements
regarding service provision has led to clear
traceability requirements on detailed system
performance history (already implemented in
EGNOS).This approach significantly improves
navigation system safety, facilitates the
detection and investigation of any
malfunctioning and allows recording of service
level performance in case of claims. In this
context, the integrity information function
plays an important role.
Law enforcement in the road and maritime
domains, road charging and tolling, safety of life
navigation in all modes of transport will soon
rely on dedicated infrastructures with
reliability and guarantee characteristics that
are simply not available with current systems. [2]
GALILEO and EGNOS will make possible a whole new and virtually limitless range of ‘reliability-critical' services, applications and business opportunities.
EGNOS already delivering public and private benefits. Thanks to its increased reliability, EGNOS makes possible a number of efficiency gains and cost-savings across the industries where it is used: aviation, road, rail transport, SISNeT technology, agriculture (I), agriculture (II).
GALILEO and EGNOS now represent outstanding European flagship programmes, showing the way to an independent and state-of-the-art European GNSS, and representing a new cornerstone for the worldwide satellite radionavigation system of the future. [3]
References
[1] European GNSS Supervisory Authority
"Benefits of Galileo"
[2] Galileo Joint Undertaking
"Business in satellite navigation - An overview of market developments and emerging applications".
[3] European GNSS Supervisory Authority
"Benefits of EGNOS"
