Table of Contents
Advertisement
Vision Series Installation and Operating Handbook
Modem Paired Carrier Processing
Paired Carrier can be added to existing systems as w ell as being incorporated into the
design of new systems. The signal cancellation techniques used guarantees at least
25dB (typically 30dB) cancellation of the unw anted signal meaning that the uplink and
dow nlink 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 bandw idth for new applications and services. The
savings can be used to reduce bandw idth or increase throughput or convert to a higher
coding gain to decrease pow er.
Both symmetric and asymmetric point-to-point links are supported. Symmetric links
typically have similar antenna sizes and use similar pow er levels at each end of the link
whereas asymmetric links w il typically use a larger antenna at one end of the link and a
smaller antenna at the other end, w ith dissimilar pow er levels. In the asymmetric case,
the system can be designed to require signal cancellation at only one end of the link, w ith
the unw anted signal at the other end being reduced to a level comparable w ith system
noise.
Paired Carrier is designed for use in point-to-point links. For point-to- multipoint operation,
the Paradise PCMA-70 Satellite Bandw idth Extender can be used to overlay several
smaller carriers on top of a larger carrier and then cancel the larger unw anted 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 w orks with any
netw ork 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
8-13
Advertisement
Table of Contents
