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Re: HDTV on the "small" screen



Tom writes:


>The economics surrounding the design of receivers capable of multiple
>transport stream demodulation and multi-channel decoding present additional
>arguments favoring COFDM and layered encoding over 8VSB.
>
>With the newly available high-speed SiGe DSPs and COFDM, a single
>demodulator chip could perform the work of multiple tuners.  The unique
>aspect of CODFM is its use of thousands of separate carrier frequencies for
>each 6 MHz transport stream channel.

At last year's winter SMPTE Conference in Toronto, Canada, Wayne Luplow of
Zenith Electronics presented a detailed overview of the ATSC 8VSB
transmission system.  He mentioned that in its earlier investigations, the
committee examined COFDM in great detail.  They concluded that even with
advanced manufacturing techniques, the benefits of COFDM when restricted to
6 MHz TV broadcast channels (a mandatory imposition of the FCC in the United
States) did not outweigh the cost or complexity when compared to 8VSB.  Nor
is COFDM the best "fit" with the American TV broadcasting model, which tries
to maintain at least a semblance of regional diversity.  On the other hand,
COFDM on 8 MHz channels works a lot better to begin with, and it is a better
"fit" with the European situation, where single-frequency networks make a
lot of sense and where national borders need to be respected.


Best regards,
Christopher Bacon




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