About GLONASS

GLONASS is the Russian Federation’s GNSS—literally. The Russian acronym stands for GLObal'naya NAvigatsionnaya Sputnikovaya Sistema, or Global Navigation Satellite System.

Chronologically the world’s second GNSS system, both the program (established in 1976) and the first launch of a GLONASS satellite (October 12, 1982) followed the corresponding United States GPS milestones by a few years.

Although a full constellation was achieved in 1995, the economic collapse that followed the fall of the Soviet Union led to its underfunding and eventual decline to only seven operational satellites by 2001. That year, President Vladimir Putin initiated a program to revive and modernize GLONASS, with a definitive government degree issued on August 21, 2001.

As of December 26, 2007, GLONASS had 18 satellites in the system’s three orbital planes at an altitude of 19,100 kilometers); three spacecraft were temporarily switched off. Another three modernized GLONASS-M launched on December 25, 2007, are expected to begin broadcasting within five to six weeks. The current plan calls for initial operational capability (18 satellites on orbit) to be achieved in 2008 and 21 satellites plus three on-orbit spares, by 2009. Full operational capability (FOC) is expected in 2011 with the 24-satellite constellation comprising all modernized spacecraft (GLONASS-M) and next-generation spacecraft (GLONASS-K, to begin launching in 2009).

Since its inception, the Russian GNSS system has employed frequency division multiple access (FDMA) techniques in which the same code is used for the signals broadcast by the system, with individual spacecraft being distinguished from one another by a specific frequency allocation. Open signals are broadcast at L1 and L2, along with encrypted military signals.

The FDMA approach has left Russia as the exception to the use of CDMA signals by the U.S. Global Positioning System (GPS), Europe’s Galileo system and China’s Compass/Beidou. In CDMA systems, satellites are distinguished by different pseudorandom noise codes broadcast on the same frequencies.

As a result, GLONASS signals are not as easily incorporated into user equipment that exploit a combination of GNSS systems to provide positioning, navigation, and timing (PNT), although a growing number of GNSS receiver manufacturers are including GLONASS capability on their equipment. As of late 2007, Russian officials were evaluating whether to add a CDMA signal to GLONASS. No decision had been announced as of early 2008.