While GPS is currently leading the pack in terms of satnav system implementation, at a recent UN International Committee on Global Navigation Satellite Systems conference it was clear that competing systems are getting closer and could overtake it during the next decade. Presentations from Europe, Russia and China described active developments of worldwide satnav constellations, while India and Japan are moving ahead with regional networks. Though their signals will be compatible with GPS, these aren’t simply clones, and Europe’s Galileo, Russia’s Glonass and China’s Compass will offer several capabilities and services not currently available from GPS.
With its first satellite launched in the late 1970s, GPS has certainly been a trailblazer and today supports more than 300 million land, sea and airborne users around the world. Furthermore, the USAF spends some $1 billion per year to ensure consistently improving global performance, replacing older satellites with updated units that have progressively increased its accuracy and reliability.
However, one perceived major shortcoming of the system is that it employs too few satellites. GPS is a 24-satellite system, and while the Air Force diligently works to maintain that number, the military needs only 21, and that’s a concern for civil aviation interests. Although spare satellites are in nearby “parking” orbits, it takes time to move them to replace failed units.
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