[opendtv] Re: China writes its own digital TV standard
- From: "Bob Miller" <robmxa@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Sat, 1 Jul 2006 00:33:47 -0400
On 6/30/06, Manfredi, Albert E <albert.e.manfredi@xxxxxxxxxx> wrote:
>
> Bob Miller wrote:
>
> > I have said in the past that if 8-VSB could be made to
> > work I would like to use it. The question is can it be
> > made to work with current receivers. Both E-VSB and A-VSB
> > do not work with current receivers IMO.
>
> They do. It's just that current receivers cannot make use of the new
> robustness. Just like DVB-H (when sent along with DVB-T in the same
> channel). Legacy receivers can't use that either, but at least DVB-H
> doesn't break the legacy receiver.
I will not and have not argued that DVB-T receivers are compatible with
DVB-H because they are not at least by my definition of compatible. It is
disengeneous, IMO, to argue that since DVB-H, E-VSB or A-VSB don't "break"
legacy receivers they are compatible. They are new modulations that are NOT
receivable by current receivers period and therefore, IMO, incompatible with
current receivers. If you were to dedicate all 6 MHz to E-VSB or A-VSB all
current receivers would not receive anything anymore than if you were using
COFDM. No only reason you would not do that is because the FCC does not
allow it. You have to have at least one SD program in MPEG2 and 8-VSB that
is receivable by all current receivers.
It is amazing how twisted logic can be when you want to get around the
obvious. E-VSB and A-VSB are not fixes for 8-VSB they are new modulations
that are incompatible with all current receivers.
> Any talk of any fix to 8-VSB that renders current
> > receivers obsolete partially or totally opens the door
> > to consideration and comparison to ALL other
> > modulations.
> >
> > That would include ADTB-T (VSB) IMO.
>
> For *us*, sure. For the Chinese, that's another matter. They are making
> changes to *both* COFDM and 8-VSB, and these changes might not be
> backward compatible at all. Or at least, they are likely to degrade
> legacy receivers. But they are making something new, so anything goes.
They are not backward compatible. They are new modulations. They don't work
with any legacy COFDM or 8-VSB receivers. They didn't change COFDM they are
using their own TDS-OFDM.
By the way, Brazil could have perhaps been enticed that way, to work on
> 8-VSB improvements. But I have a feeling they were looking for a lot of
> investment.
If memory serves me we were making major offerings years ago to entice
Brazil. I don't think anything was being seriously offered lately because
Brazil had probably made it very clear that they were not interested in
8-VSB period though they still did lip service to considering 8-VSB.
For us in the US, I agree that it's far more interesting to limit
> changes only to the receiver design, if possible.
As long as they are compatible with all current receivers. As soon as they
are not, as soon as we CHANGE the modulation, we should consider ALL current
modulations.
My argument is that both E-VSB and A-VSB are incompatible CHANGES of
modulation on an incremental basis. But while most assume that they will
occupy a small part of the 6 MHZ channel while HD occupies the main part I
disagree. I believe that market forces and common sense say that over time
and with competition broadcasters could/would/should/will make use of as
much of the 6 MHZ as they can for use by MPEG4 AVC with or without A-VSB.
If you can deliver an SD program in 3 Mbps or less with MPEG2 that would
leave 16.34 Mbps of bandwidth for such uses. 84.5% of the 6 MHz channel
being used to deliver content incompatible, by codec or modulation, with all
current receivers. Ah but we could fix that with an add on MPEG4 AVC unit
like USDTV and throw in A-VSB as well. That fix would probably cost twice as
much per "fixed" receiver as a COFDM HD receiver in US quantities would
cost. And you couldn't fix those as yet not invented converter boxes if they
are made to Congressional specs and have NO extra features.
The contortions and semantics to stay in bounds with 8-VSB are getting more
surreal as the years tick by.
So the plan now is to take a 6 MHz station and limit the SD MPEG2 content to
3 Mbps, deliver as much content as possible with A-VSB in the remaining
bandwidth using MPEG4 AVC. But we don't know the specs of A-VSB yet. Don't
know when it might be available. Don't know who will build the chips or the
receivers. To get manufacturers really on board we would have to have a good
majority of broadcasters really on board it seems to me.
So I say to investors, you know that great idea we had in 1998? Well it
looks like we might be able to do something like that, maybe, with half the
bits we planned on sometime by maybe 2010.
On the other hand I have talked to two manufacturers who believe that there
might be a market for A-VSB next year and are working on it in some fashion.
Neither was Samsung. Next week I am going to do my best to find out what the
real parameters of A-VSB are since mine are so far off the mark. Still think
it would be easier to go back to Congress and tell them that they made a
mistake.
Bob Miller
Bert
>
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