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

  • From: Bob Miller <bob@xxxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Sat, 09 Oct 2004 01:36:30 -0400

Manfredi, Albert E wrote:

>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
>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.

The point is not that COFDM can go to a higher bitrate but that at an 
equal or slightly higher bitrate it is still more robust than 8-VSB. And 
from there you can dial it down to whatever datarate and robustness 
combo you want.

If this was a horse race and COFDM and 8-VSB were nose to nose with a 
quarter to go yes Vive la difference but in this race COFDM won 
yesterday and 8-VSB is still at the starting gate. Why are we bothering 
with it at all?

8-VSB should be a hobby not a modulation for the US.

Talking to the FCC the other day went like this, "but COFDM was just so 
late arriving", what do you call 2004 December for the arrival of 
minimally acceptable 8-VSB was my answer.
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