Introduction - Understanding GPS: Principles and Applications - page 7

Figure 1.3 Block IIF satellite. ( Source: The Boeing Company. Reprinted with permission.)

It is anticipated that the SOL service will authenticate the received satellite sig-
nals to assure that they are truly broadcast by GALILEO. Furthermore, the SOL ser-
vice will include integrity monitoring and notification; that is, a timely warning will
be issued to the users when the safe use of the SOL signals cannot be guaranteed
according to specifications.
A 30-satellite constellation and full worldwide ground control segment is
planned. Figure 1.4 depicts a GALILEO satellite. One key goal is to be fully compat-
ible with the GPS system [12]. Measures are being taken to ensure interoperability
between the two systems. Primary interoperability factors being addressed are sig-
nal structure, geodetic coordinate reference frame, and time reference system.

Figure 1.4 GALILEO satellite. (Courtesy of ESA.)