Locata : a new constellation for high accuracy outdoor and indoor positioning
Rizos, Chris et al.
The Global Positioning System (GPS) is the best known, and only currently fully operational, Global Navigation Satellite System (GNSS) providing positioning capability anywhere in the globe, on a continuous 24/7 basis, with accuracies ranging from the dekametre-level to the sub-centimetre-level. Despite this versatility, GPS/GNSS cannot satisfy the high accuracy positioning requirements for many applications in engineering and mining surveying, machine guidance/control, structural monitoring, urban and indoor positioning. Russia has deployed its own GNSS called GLONASS which will be fully operational by the end of 2010. Fueling growth in precise positioning applications will be next generation GNSSs that are currently being developed and deployed, including the U.S..s modernised GPS-IIF and GPS-III, the revitalised GLONASS, Europees GALILEO system, and Chinaas COMPASS system. Furthermore, a number of Space Based Augmentation Systems (SBASs) and Regional Navigation Satellite Systems (RNSSs) will add extra satellites and signals to the multi-constellation GNSS/RNSS mixx. The main advantage that the multi-GNSS era will bring is more satellites. It is estimated that by 2015, if the planned deployments go ahead, there will be of the order of 150 with perhaps six times the number of broadcast signals on which measurements can be made, compared to todayys GNSS availability. However, despite these planned extra satellite constellations the fundamental challenge of space-based positioning remains to deliver high accuracy in areas where direct line-of-sight to four or more satellites is not available, as is the case in deep open-cut mines, heavily wooded, rugged terrain, urban and indoor environments.
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