TY - JOUR T1 - Multi-Constellation System as Augmentation to GPS Performance in Difficult Environment or Critical Applications JF - ATTI DELL'ISTITUTO ITALIANO DI NAVIGAZIONE Y1 - 2009 A1 - ANGRISANO, A A1 - GAGLIONE, S A1 - PACIFICO, A A1 - VULTAGGIO, M AB -
The GPS Standard Positioning Service (SPS) does 
not provide suitable performance in all environment
conditions or in every possible applications. In 
severely signal degraded environments, e.g. 
mountainous or urban areas, where a lot of GPS 
signals are blocked by buildings or natural 
obstacles, the positioning is inaccurate because of
bad satellite configuration or impossible owing to 
lack of minimum number of visible satellites. 
Otherwise GPS SPS is inadequate for critical safety
applications like aircraft take-off or landing, because 
does not satisfy the Required Navigation Parameters
(RNP) relative to these flight phases. 
To solve the GPS gap on regional scale, space-based
augmentations could be employed. In this study a 
simulation is carried out, considering GLONASS 
and EGNOS GEO constellations and a set of 3 
geosynchronous satellites (similar to QZSS space 
segment). A software for constellation analysis is 
developed in MATLABĀ® environment to evaluate 
the considered augmentations performances in 
critical conditions (urban canyon or critical phase of 
flight). The used indicators to evaluate coverage 
performance are the VSN (Visible Satellites 
Number), DOP (Dilution of Precision) and the 
probability that integrity is available to be computed 
in autonomous. 
 
VL - 190 N1 - Paper Selected from the ENC - 2009 Conference held in Naples on 4 - 6 May 2009 ER -