[opendtv] Re: Democrats Air Concerns About Analog Switchover

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Sun, 19 Nov 2006 18:57:35 -0500

Richard Hollandsworth wrote:

> 2. Only the latest and greatest "5th Gen" ATSC Decoder chips
> "meet" the A/74 Receiver Guidelines....and only the new
> Samsung DTB-H260F STB has a "5th Gen" chip.  Hence, all other
> "current" STBs can be expected to exhibit the same deficient
> performance documented in FCC-05-199.

One caveat: much of what's in A/74 is addressed by the tuner and not by
the demod. So in fact, you can have a good 5th gen demod that doesn't
give the performance you'd hope for.

Another point: "latest and greatest?" we're talking about technology
from 2003!! How is that "latest and greatest?" In fact, the mid-2005
Samsung Gemini measures much better than the LG. The question we should
ask is, HOW COME "all other 'current' STBs" aren't up to technology
demoed such a long time ago now? As to built-in receivers, I only have
anecdotal evidence that they perform much better, and I have no idea
which sets have the best ones. I see no test results anywhere. How come?

That's why I think all the talk about how great it would be to have
DVB-T receivers here in the US simply misses the point. Until we find
out precisely what it is that keeps innovative solutions away from the
DTT market in the US, any speculation about DVB-T in the US is idle

> 3. ATI submitted similliar test results for their "latest"
> ATSC Decoder chips:
> Note the HUGE improvement with the latest two ATI chips
> (Theater?? Xilleon??) compared to other (unidentified) STB's,
> including what they called a "Third Gen" Receiver:.  FYI:
> Xilleon 240H is used in the Samsung DTB-H-260F.

That's encouraging, but where are the test results of these ATI chips
from the CRC? How good is the tuner in the Samsung STB?

> 4. If you look at the CRC test results on the PROTOTYPE
> LG/Zenith "5th Gen" Receiver, you will see that it did not
> perform well with short delay, nearly equal strength multipath
> test conditions, including Brazil "C" and "E" test conditions
>...such as can occur with an indoor or attic mounted antenna.

First of all, it is instructive to note WHEN the CRC tested this
already-integrated-in-chip-form 5th gen demod. It was September 2003.
Isn't it funny that such a ready product still hasn't been able to be
incorporated in an STB at the end of 2006. That must be a record for a
company deliberately not wanting to compete.

But I don't agree that the 5th gen was poor at close echoes. Anything
that allows reception when close and loud echoes are withing fractions
of a dB is excellent. Yes, the LG showed a slight degradation inside of
0.1 usec, but that meant reception with echo 0.5 or 0.6 dB down rather
than 0.1 or 0.2 slightly further out. Hardly "poor." See Table 4a, Table

Brazil C showed reception at 14.4 dB of C/N, meaning that the demod made
use of echo energy. Not bad. Brazil E (3 equal strength paths, 1 usec
apart) showed reception at 23.8 dB, which puts it on a par with COFDM
receivers. Again, not bad. The CRC test of the Linx (from 2002!!)
included "with reacquisition," which I think is important, and that
managed reacquisition in Brazil E with 24.8 dB of C/N. The test of the
LG did not include this info.

> 7. I have severe multipath and my Sylvania 6900DTE's
> "deficient" ATI NXT2004 ATSC Decoder chip doesn't always
> provide flawless performance--despite help from a DTA-5000
> Smart Antenna.

I can only go by the customer reviews they have at the Circuit City and
Radio Shack web sites. It appears from these that the Accurian and
Digital Stream clones were the best performers of this 3rd generation
batch of STBs.

> And when it recovers, there is a HUGE SNAPPING GRUNCH noise that
> comes out of the Surround System....at which time my wife covers
> her ears and exits to find another TV....

That is the sort of experience any self-respecting CE magazine would
describe. But in the interest of complete disclosure, this has NOTHING
to do with ATSC. Surely, a poor design execution of one brand of STB
doesn't mean anything. I have no such problem with my STBs. The Accurian
does exhibit a bit of a loud pop, to the subwoofer, when it's initially
turned on or off, so I turn down the volume when first powering up. So
what? These are indictments of less than perfectly turned out products,
not the ATSC standard.

If things are to get better for DTT here, we need less idle speculation
from those with axes to grind, and more real information. Why are good
STBs so late in coming and so hard to find? The technlology does exist.

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