SUMMARY CHARACTERISTICS OF THE W SATELLITES

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The W Satellites
• Channels D1, D3, D1S and D3S can each receive from either the fixed coverage or the steerable coverage,
the choice of uplink coverage being made on a channel-by-channel basis.
• Channels D5, D7, D5S and D7S can each receive from either the fixed coverage or the steerable coverage,
or simultaneously from both coverages, the choice of operational mode being made on a channel-by-
channel basis.
The eight channels with cross-connection capability are identified in Figure 1. The following operational
possibilities are provided for all eight channels:
• A signal received from one coverage (fixed or steerable) can be transmitted to the other coverage. For
example, the channel pair D3 and D3S could be used to provide bi-directional communication between the
fixed coverage and the steerable coverage.
• A signal received from any given coverage can be simultaneously transmitted to both coverages. For
example, the channel pair D1 and D1S could be used to “broadcast” the same signal received from the
steerable coverage to both the fixed and steerable coverages.
In addition, Channels D5, D7, D5S and D7S each provide the possibility to receive signals from both coverages
and to transmit them to a single coverage or to both coverages. In this case, performance in terms of G/T takes
into account the wider uplink coverage and discrimination between uplink carriers must be ensured through
FDMA (i.e. the spectra of the carriers must not overlap).
For example, the lower half of the 54 MHz bandwidth occupied by the channel pair D5/D5S could be used to
receive traffic from the fixed coverage whilst the upper half could be used to receive traffic from the steerable
coverage. The combined traffic could then be transmitted to the fixed coverage via Channel D5 and
simultaneously to the steerable coverage via Channel D5S. This type of networking between two different
coverages can offer attractive mission features for certain types of services.