What is in this article?: - Next-generation broadcast: more
bandwidth for the future - Audio compression The development of
new broadcast technologies that offer higher efficiencies and/or
performance is an ongoing quest, with researchers continuing to
push on methods to achieve a higher data throughput. The result
is that the hardware and software providing media delivery will
continue to evolve. On the broadcast side, modulation and
compression are key components of a next-generation broadcast
system. Digital modulation customarily takes the form of
transmitting symbols that are mapped from groups of bits. These
symbols can be sent using one of a variety of modulation
schemes, including VSB, QAM and COFDM. Because reception is
usually limited by channel noise, interference and distortion,
there is a certain carrier-to-noise (C/N) ratio that is required
for error-free reception. For this reason, the symbol rate is
usually limited in a channel, regardless of the number of
different symbols (or constellation p