Other Global Navigation Satellite Systems
GPS is sometimes referred to as a global navigation satellite system (GNSS). At this time, it is the only fully operational GNSS. Russia operates a partially operational GNSS known as GLONASS. The European Community is currently developing a third GNSS called Galileo.
GLONASS
Russia has operated GLONASS since the 1980s. It is similar in design to GPS, but based on different technical standards. Like GPS, GLONASS offers a civilian service for peaceful worldwide use, free of direct user charges, and an encrypted military service. In the 1990s, the GLONASS constellation deteriorated, making the system less popular among users. Russia is currently rebuilding and modernizing GLONASS with the intent of restoring full operational capability by 2009. The United States is cooperating with Russia towards GPS-GLONASS interoperability, both for enhanced PNT and combined search and rescue capabilities.
Galileo
The European Commission announced its plans to develop an independent GNSS in 1999. Galileo is intended to be a primarily civilian system that will be operated by a commercial entity. It will offer at least one open service free of direct user fees and at least one commercial service on a subscription basis. Current plans are to achieve operational status around 2011. Europe is partnering with many nations around the world to promote Galileo use. Under a cooperative agreement signed in 2004, the United States and the European Community have designed common signals to be transmitted by both GPS and Galileo, enabling interoperability at the user level.