SATELLITE SYSTEMS - GPS Satellite Surveying - page 90

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The most recent launch of three satellites as of this writing (summer 2002) took
place on December 1, 2001. The GLONASS program is also undergoing a modern-
ization. The new series of satellites is called GLONASS-M. The interface control
documents provide some information on the new (planned) features. The interested
reader is advised to consult the current literature to learn about ongoing developments
and the status of the GLONASS constellation.
Finally, GLONASS satellites have been used successfully for accurate baseline
determination since the mid-1990s (Leick et al., 1995). The additional difficulties
encountered in baseline processing because of GLONASS satellites transmitting on
different carrier frequencies will be discussed in Chapter 7. GLONASS observations
have primarily been used to supplement and strengthen GPS solutions. The improved
productivity when including extra GLONASS satellites is clearly noticeable and has
heightened the expectations among practitioners for the not-to-distance future when
more GLONASS satellites are available again, Galileo becomes available, and, in
general, the modernization of the systems has progressed.

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3. 4 GALILEO

O n March 26, 2002, the European Council agreed on the launch of the European
Ci vil Satellite Navigation Program, called Galileo. Civilian European institutions
fu nd this program but complementary financing by public-private partnership is also
un der consideration. Some of Galileo's services might eventually be subject to a user
fe e. The space segment is expected to consist of a global constellation of about thirty
sa tellites, distributed over three planes. The nominal orbits are expected to be circular,
with semimajor axes being close to those of GPS and GLONASS. Consult Galileo
(2002) for up-to-date information on this satellite system, in particular, regarding the
details of signal structure and the definition of the various services. The status of
Galileo as of fall 2002 can be found in Hein et al. (2002).
As can be seen from Figure 3.14, the Galileo E5A signals share the frequency band
with GPS L5. The adjacent region is reserved for Galileo E5B. At the World Radio
Conference (WRC) 2000 at Istanbul, Turkey, several decisions were made that deal

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E3

E4 E2 E1

E5A

E5B E6

L2 G2

L1 G1

L5

1300 1559 1610

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Figure 3.14 Allocation of GPS, GLONASS, and Galileo frequency bands. GPS: L1, L2,
L5 ; GLONASS: G1, G2; Galileo: E1, E2, E3, E4, E5A, E5B, E6. The symbols E1, E2, E3, and
E4 indicate the location of very narrow bands.