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.

More recently, the GLONASS program — after an allocation of more than
100 billion rubles (nearly $3 billion) in funding for its 2002–2011
modernization effort — has progressed most steadily of all of the GNSSes.

With the three newest satellites from a launch in December 2008 now in
operation, GLONASS has a 20-bird constellation — including 19
modernized space vehicles (SVs), the most in more than a decade. Some
17 of the spacecraft are broadcasting a second full civil signal on the
GLONASS L2 frequency, the only such GNSS system doing so.

Its signal-in-space user range error (URE) is down to 1.8 meters —
still high compared to GPS’s 1-meter URE, but within the 3.7 meters
called for in the GLONASS Interface Control Document (ICD) and several
times better than the UREs of just year ago. By the end of last year,
GLONASS was typically providing a standalone receiver with five-meter
positioning accuracy using pseudoranges.

Launches have taken place regularly as scheduled over the past few
years, and another six satellites are set to go up in triple launches
in October and December 2009. If successful, that should bring the
GLONASS constellation to full operational capability (FOC) with 24
satellites early in 2010.

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.

The next-generation GLONASS-K that will begin
launching in 2010 will include a CDMA (code division multiple access)
signal on L3, which will more closely align with other GNSS systems
that the system’s legacy design.

A decision about new GLONASS signals at the L1C and L5 frequencies
depends on negotiations by a U.S./Russia working group, but could lead
to additional CDMA signals, said Sergey Revnivykh, deputy director of
the Russian space agency’s Mission Control Center in early 2009.