TABLE OF CONTENTS The GNSS applications are represented by old fundamental systems for Position, Velocity and Time (PVT) military determination systems such as GPS and GLONASS for US or former-USSR requirements, respectively. The GPS or GLONASS are old GNSS giving positions to about 30 metres and they therefore suffer from certain weaknesses, which make them impossible to use as the sole means of navigation for ships, particularly for civil aviation. In this way technically, GPS and GLONASS systems used autonomously are incapable of meeting civil aviation's very high requirements for integrity and position availability and precision in particular are insufficient for certain critical flight stages. Because these two systems are developed for military utilization, many countries and international organizations would never be dependent on or entrust people's safety to GNSS systems controlled by one country. Augmented GNSS solutions of GSAS were recently developed to improve the mentioned deficiencies of current military systems.
GNSS augmentations are available to enhance standalone GPS or GLONASS satellite PVT performances for maritime, land and aeronautical applications. Moreover, user devices can be configured to make use of internal sensors for added robustness in the presence of jamming, or to aid in vehicle navigation when the satellite signals are blocked in the "urban canyons" of tall city buildings. Some special applications, such as maritime and especially aeronautical, require far more accuracy than standalone GPS or GLONASS.
Accuracy can be improved by removing the correlated errors between two or more satellite receivers performing...
