GPS modernisation and GNSS development

Satellite navigation has enabled a large number of new applications among many groups of users, but a number of limitations have been observed, especially with respect to reliability and integrity of satellite navigation signals. The article deals with global navigation satellite systems (GNSS), analyzes benefits of satellite based systems, as well as problems with positioning accuracy, signal availability and system integrity. The current GPS signal structure was developed some 30 years ago, and the planned further modernization of the system meets the future requirements, improve positioning accuracy, signal availability, and system integrity. The new European Galileo system is a more efficient and reliable alternative to the GPS system. Galileo system offers superior and constant accuracy, reliability, and the very high level of continuity