[opendtv] Re: Zoran, Thomson team on digital TV reference design

From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>
Date: Tue, 29 Nov 2005 16:32:07 -0500

Mark Schubin wrote:

> Richard Hollandsworth wrote:

> > [A/74] "suggests" some multipath performance profiles for
> > static pre-echo and post-echo with varying Desired to Echo
> > ratio. The text only "suggests" a "typical" performance
> > range of -10 to + 40 usec
>
> That's not far from what used to be called "2nd generation."
> First generation was -3 to +10.  Second was -10 to +30.  So
> were third & fourth.  Fifth is -50 to +50.

But not quite, according to the CRC numbers anyway, if you dig
into the actual numbers. Really they are all closer to that
Figure 4.3 of A/74 than one might think when reading the
press releases.

The short version is that the Linx is the best for echo
tolerance of really loud echoes, but the other two are better
than the Linx for max echo tolerance of weaker echoes. So
results will vary depending on your specific conditions, one
would think.

According to the CRC measurements, which I caution are a couple
of years old for the LG and Linx designs:

4th gen Linx is -38 to +38 usec for -10 dB echoes
-8.5 to 38.5 usec for -3 dB echoes
-17 to +17 usec for 0 dB echoes.

5th gen LG is -50 to +50 usec for -10 dB echoes
-12 to +12 usec for -2.5 dB echoes
-1 to +1 usec for echo strength within less than 1 dB (i.e.
loud, but not quite 0 dB). This is odd, because it does
do as well as Linx in the Brazil E test. So there's a slight
discrepancy in these results.

So as you can see, the 4th gen Linx is actually better than
the 5th gen LG in some respects. It's a mixed bag.

Samsung is -45 to +55 usec for -7 dB echoes (similar to LG)
-14 to +55 usec for -1 dB echoes (way better than LG or Linx)
-10 to +15 usec for 0 dB echoes, with a slight glitch in the
middle of that span, which is not quite as good as Linx, but
better than the LG.

So the devil is in the details. The Linx really rocks in some
respects, compared with the other two.

A/74 wants reception with -10 to +40 usec echoes at -5 and -6 dB
echo strength, for example, which the 4th gen Linx almost meets,
the LG does not meet, and the Samsung meets easily.

A/74 also wants reception with -25 to +50 usec echoes of -16 dB
strength, which the Linx does not meet, and the LG and Samsung
easily meet.

Bert

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[opendtv] Re: Zoran, Thomson team on digital TV reference design

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