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Nowadays, when analogue TV distributing networks provide neither quantity
nor quality of programs, forming digital packages of TV programs is an
alternative solution. It allows to save frequency resource and to increase program
capacity and quality. Using MMDS (Multichannel Multipoint Distribution System)
technology it is possible to deliver up to 60 channels (QAM64 modulated) and
to cover ranges of up to 50 km. MMDS transmitter signal can be used by either
a subscriber or CATV operators. The fact that signals used in CATV network
and in MMDS transmitting system are of the same format considerably simplifies
interaction between them. Thus MMDS signal received by subscriber’s converter
can be fed into any CATV network without processing. At that Conditional
access system can be „end-to-end”, in other words signals scrambled by
MMDS transmitters remain encrypted when transmitting in CATV network
if they have been received by subscriber’s MMDS converter and have been
fed into a CATV network without processing. In order to feed a signal received
from “on-air” system into a CATV network, it’s enough to amplify received signal
and to combine it with CATV signals.
