Page 27 - Satellite Communications, Fourth Edition

Overview of Satellite Systems 7

Figure 1.2 (Continued).

The INTELSAT VII-VII/A series was launched over a period from
October 1993 to June 1996. The construction is similar to that for the
V and VA/VB series, shown in Fig. 1.1, in that the VII series has solar
sails rather than a cylindrical body. This type of construction is described
in more detail in Chap. 7. The VII series was planned for service in the
POR and also for some of the less demanding services in the AOR. The
antenna beam coverage is appropriate for that of the POR. Figure 1.3
shows the antenna beam footprints for the C-band hemispheric cover-
age and zone coverage, as well as the spot beam coverage possible with
the Ku-band antennas (Lilly, 1990; Sachdev et al., 1990). When used in
the AOR, the VII series satellite is inverted north for south (Lilly, 1990),
minor adjustments then being needed only to optimize the antenna pat-
terns for this region. The lifetime of these satellites ranges from 10 to
15 years depending on the launch vehicle. Recent figures from the
INTELSAT Web site give the capacity for the INTELSAT VII as 18,000
two-way telephone circuits and three TV channels; up to 90,000 two-way
telephone circuits can be achieved with the use of “digital circuit mul-
tiplication.” The INTELSAT VII/A has a capacity of 22,500 two-way
telephone circuits and three TV channels; up to 112,500 two-way tele-
phone circuits can be achieved with the use of digital circuit multipli-
cation. As of May 1999, four satellites were in service over the AOR, one
in the IOR, and two in the POR.