Quantum and Evolution Series Installation and Operating Handbook
8-58
Quantum 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 (bits/s/Hz)
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 and then cancel the larger unwanted carrier
using a single PCMA-70, 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 including star topology (hub/spoke,
one-to-many), FDMA mesh (single satellite hop, many-to-many), hybrid star mesh, Single
