Introduction to GNSS - GNSS Remote Sensing: Theory, Methods and Applications - page 9

Sputnikovaya Sistema, GLObal NAvigation Satellite System in English) is the
Russian-owned constellation of positioning satellites (GLONASS-ICD, 2008). It
reached full operational capability in 1995, after the efforts made by the collapsed
Soviet Union were continued by the Russian Federation. Unfortunately, due to
the inability to maintain the system, the constellation slowly reduced, reaching a
minimum of eight operational satellites in 2002. The turning of the century saw
a renewed interested in restoring the full capability by the Russian government
(Dvorkin and Karutin 2006 ), and the system is currently (2011) formed by 20
operational satellites. The GLONASS space segment is composed of 24 satellites
distributed over three orbital planes (separated by 120 right ascension of the
ascending node) with radius equal to 25,500 km and 65 -inclined. GLONASS
satellites broadcast signals in L1 and L2 bands, using Frequency Division Multiple
Access (FDMA) technique as channel access method technique. The GLONASS
ground control center in Moscow and the telemetry and tracking stations are all
within the Russian Federation borders.

1.1.3 GALILEO

The Galileo navigation system, named after the Italian astronomer and physicist
Galileo Galilei, was started following political reasoning that wanted European
countries to be independent, in the context of satellite navigation, from the US's
GPS and Russian GLONASS. GPS and GLONASS can theoretically be turned on
in any moment by their respective nations, making European countries particularly
vulnerable. Since its dawn, the Galileo system was intended to provide a more
precise navigation service than the one provided by either GPS or GLONASS
(Mendizabal et al. 2008 ). In March 2002, The European Union (EU) and European
Space Agency (ESA) agreed to develop the Galileo positioning system, which is
expected to be fully functional by 2020. Galileo is currently under development to
be completed within the decade 2011-2020, which is expected to be compatible
with the modernized GPS system. The receivers will be able to combine the signals
from both Galileo and GPS satellites to increase accuracy significantly. Compared to
US's GPS and Russian GLONASS, Galileo is designed specifically for civilian and
commercial purposes. Currently, a number of countries participated in the Galileo
project, e.g., China in 2003, Israel in 2004, and next 1 or 2 years the Ukraine, India,
Morocco, and Saudi Arabia as well as South Korea. In 2007, the 27 members of the
European Union collectively agreed to move forward with the project, with plans
for bases in Germany and Italy [EU-Galileo].
Two Galileo System Test Bed satellites (Giove A and B), dedicated to take the
first step of the In-Orbit Validation phase towards full deployment of Galileo, are
fully operational and broadcasting on L1, E5 and E6 bands. The full constellation
will consist of 30 satellites distributed over three orbital planes (56 inclinations),
at an altitude of approximately 29,600 km. Each satellite will revolve around the
Earth at a rate of one revolution every 14 h. The signals will be broadcast in the L1,