[opendtv] E-VSB Turkey (was Re: [opendtv])
- From: Eory Frank-p22212 <Frank.Eory@xxxxxxxxxxxxx>
- To: "'opendtv@xxxxxxxxxxxxx'" <opendtv@xxxxxxxxxxxxx>
- Date: Fri, 8 Jul 2005 03:12:19 -0700
Mark Aitken wrote:
>Based on a resent response (letter) from the FCC regarding a specific
>matter, the FCC has expressed that on a practical level, if a
>Broadcaster uses E-VSB (part of the current ATSC Standard A/53C with
>Amendment No. 1 and Corrigendum No. 1: ATSC Digital Television Standard,
>Rev. C.) the only concern they would have would be if there was no
>"normal" VSB available for minimum content reception. Otherwise, one can
>use E-VSB today without an STA (but notice would be appreciated). There are
>other promising methods being reviewed inside ATSC activities
>that may lend well to helping resolve concerns in some areas of ATSC
>performance. Join the ATSC process (or at least participate...you only
>need be a member to vote if you have direct and material interest in the
>activities.) if you want to know more...
It is unforgivably irresponsible of the FCC to allow broadcasters to use E-VSB
under such loose restrictions. This is completely unproven technology for which
there are very few transmitters or receivers deployed. Not to mention it will
stagnate rather than accelerate viewer acceptance of the HDTV-driven DTT
transition.
Manfredi, Albert E wrote:
>EVSB is meant to be a hierarchical
>modulation sort of service rather than a complete replacement of the
>19.3 Mb/s channel. And even then, the ATSC seems to think it's okay to
>cut the capacity down to 8.5 or 4.3 Mb/s total, off prime time.
>
All it was really meant to be was a delay tactic to buy more time to improve
8-VSB receivers and stymie the COFDM rabble-rousers.
>The nice thing about E8-VSB is the way it permits very
>narrow robust channels to be created, taking away as little
>as possible from the wide stream capacity. It gives a lot
>of granularity in that way.
It permits no such thing. Increased FEC power is useless if you don?t have
signal acquisition ? for example, due to multipath. There is no real-world
evidence that these E-VSB streams result in any real-world improvements in
receivability for urban or suburban viewers. Far-field rural viewers who are
more noise-limited than multipath-limited may benefit from the extra dB?s, but
that?s about it. ?taking away as little as possible from the wide stream
capacity? is a total joke. You know better, Bert. The bit rate penalty on the
wide stream is enormous, even for modest amounts of so-called ?robust? E-VSB
data.
> On the other hand, it does not allow for
>fine tuning of the robustness of the whole 6 MHz band. That could have
>been done by directly changing the FEC used in the band, but such a
>scheme would not have been backward compatible. EVSB had to be layered
>over the 8-VSB, 2/3 trellis, and RS[208,188] FEC that was already
>there.
It isn?t backward compatible anyway, so what?s the point?
>
>Anyway, it's still IMO well suited to the task you
>suggested. But here too, some field trials would be nice.
>
Field trials would reveal the truth, and nobody wants that. Just call it
?robust? and maybe people will believe it. Meanwhile, any broadcaster who uses
it will alienate his HDTV viewers by destroying the very thing that made them
interested in his DTT channel in the first place?all in the hopes of picking up
a handful of extra rural viewers in the far-field, where the lower Gaussian
noise threshold of E-VSB could actually result in a measurable improvement.
What the heck, the urban & suburban viewers all have cable & satellite anyway,
where there is plenty of non-broadcast high-def to watch. Broadcasters who
squander that high-def advantage on E-VSB snake oil will do so at their own
risk.
-- Frank
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