[opendtv] Re: (No Date: Tue, 28 Sep 2004 10:30:37 -0400

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: "OpenDTV (E-mail)" <opendtv@xxxxxxxxxxxxx>
  • Date: Fri, 8 Oct 2004 14:18:19 -0400

Bob Miller wrote:

> If Germany and the UK chose a lower data rate for
> a more robust reception fine. They can with COFDM.
> But they could have chosen a higher data rate with
> COFDM than the 19.34 Mbps of 8-VSB and still be more
> robust than 8-VSB as was demonstrated in Congress in
> 2000

I agree that COFDM could be tuned to provide an even
higher bit rate. If you go to the max, in a 6 MHz
channel, you would be capable of 23.75 Mb/s (compared to
19.39 Mb/s for the non-E version of 8-VSB). In an
indoor environment, but not quite as bad as Brazil E
(two loud signal paths and many other weaker ones),
this 23.75 Mb/s should require 27.9 dB of C/N.

The open question is how the LG 5th gen tuner compares
with COFDM at equal bit rates today, and how that
comparison will change in years to come. Although I'm
not positive about this, because I never saw a very
thorough description of the LG, I doubt they have made
use of the training sequence yet. Likely this is still
blind equalization.

These are simply two different approaches to RF channel
design. One based on clever design of symbol trains,
the other based more on clever signal processing. Vive
la difference.

Bert
 
 
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