RE: WMUR HDTV to start Nov 1

[Garrett Wollman <wollman>]

<<On Tue, 13 Oct 1998 11:55:26 +0000, Dan Strassberg <dan.strassberg@worldnet.att.net> said:

> The major reason that ATSC selected 8VSB (eight-level vestigial-sideband
> digital modulation) over, say, the Cable-TV implementation of 64QAM
> (64-level quadrature-amplitude modulation), which packs the same amount of
> digital information into a 6-MHz channel, 

What's interesting is that ATSC also defined, specifically for cable
TV systems, an additional modulation -- 16VSB -- which has less
immunity from noise, but twice the bit clock (so you get 60 Mbit/s out
of a 6-MHz channel rather than just 30 Mbit/s as in 8VSB).  This
obviously translates into 10 SDTV streams per multiplex, rather than 5
streams on an 8VSB multiplex.

This would seem an obvious choice for cable systems to implement --
particularly the ones which have not already converted to digital
(e.g., Cablevision).  Given the increased capacity, it also highlights
how weak the cable companies' arguments against digital must-carry
are.

(At this point I would point out that subscribers to EchoStar (``The
Dish Network'') already have flexible MPEG-2 decoders in their homes;
one vendor -- either JVC or Matsushita, I forget which -- is already
promising that their EchoStar-compatible digital VCRs will be
upgradeable to ATV.)

- -GAWollman

- --
Garrett A. Wollman   | O Siem / We are all family / O Siem / We're all the same
wollman@lcs.mit.edu  | O Siem / The fires of freedom 
Opinions not those of| Dance in the burning flame
MIT, LCS, CRS, or NSA|                     - Susan Aglukark and Chad Irschick

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