Satellite based Navigation systems from around the world.

GPS (Global Positioning System) launched by USA is the dominant satellite navigation system around, and also the most commercialized navigation system available as of today. Many other countries are building their own or competing systems for terrestrial navigation for their commercial and/or military needs.

System [External Links]	Status	Country of Origin	Notes
GLONASS	Fully Operational since Sep 2010	Russia	Started during Soviet Union in 1976, system was restored starting 2001. Now fully operational since Sept 2010.
GALILEO	Targeted to be operational by 2014	EU and European Space Agency	Intended to provide more accurate signals than GPS and GLONASS. Project jointly run by EU and European Space Agency
COMPASS /BEIDOU-2	To cover China and adjacent regions by 2010/Early 2011, to expand to rest of the world by 2020.	China	Not an extension, but an alternate to GPS and GALILEO systems.
IRNSS	Expected to be operational by 2014.	India	Regional Navigation System envisaged by India, to be developed by ISRO expected to be operational by 2014.

Among the projects, GPS and GLONASS are now fully operational. This link here provides a brief two page technical comparison between GPS and GLONASS [External Link, PDF].

Commercially for civilian applications, a lot of ready off-the-shelf modules are available.  GLONASS modules have just started to emerge for civilian/commercial use.

Advantage of GLONASS:
By design, in GLONASS three signals were added around 2007 where the carrier signal frequencies were placed nearby to GPS, COMPASS and GALILEO signals, however not to interfere with the other systems. This enables GLONASS modules to be easily compatible with GPS, GALILEO and COMPASS signals by design resulting in low-cost and easier design for Multi-Standard GNSS receivers based on GLONASS standard. (Source: Wikipedia).

This arrangement results in more accurate and precise positional information due to a Multi-standard receiver and also a more reliable service availability. Military applications are finding it attractive because of the availability of an Alternative in the event of a hostile situation.

Some of the GLONASS modules now becoming available commercially demonstrate higher accuracy using this scheme. In one of our future posts, we will analyze one such GLONASS/GPS Hybrid module.