Q-Flex Satellite Modem Installation and Operating Handbook
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Figure 7-16 Q-Flex™ Modem Paired Carrier Processing
Paired Carrier™
can be added to existing systems as well as being incorporated into the
design of new systems. The signal cancellation techniques used guarantees at least
25dB (typically 30dB) cancellation of the unwanted signal meaning that the uplink and
downlink signals can share the same space segment. By doubling satellite throughput in
terms of spectral efficiency
Paired Carrier™
can be used to cut operational expenses
and/or free up satellite bandwidth for new applications and services. The savings can be
used to reduce bandwidth or increase throughput or convert to a higher coding gain to
decrease power.
Both symmetric and asymmetric point-to-point links are supported. Symmetric links
typically have similar antenna sizes and use similar power levels at each end of the link
whereas asymmetric links wil typically use a larger antenna at one end of the link and a
smaller antenna at the other end, with dissimilar power levels. In the asymmetric case,
the system can be designed to require signal cancellation at only one end of the link, with
the unwanted signal at the other end being reduced to a level comparable with system
noise.
Paired Carrier™
is designed for use in point-to-point links. For point-to-multipoint
operation, the Paradise PCMA-70 Satellite Bandwidth Extender can be used to overlay
several smaller carriers on top of a larger carrier. It then cancels the larger unwanted
carrier before feeding the output to the individual demodulators responsible for
processing each of the smaller carriers. The PCMA-70 works with any network topology
and any type of modem technology (so long as the outbound is an SCPC carrier)
including star topology (hub/spoke, one-to-many), FDMA mesh (single satellite hop,