[opendtv] Re: DVB-T HDTV demo using 19.7 Mbps in a 6 Mhz channel in costa rica
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Sun, 5 Mar 2006 19:22:56 -0500
Olivier Houot wrote:
http://www.dvb.org/documents/newsletters/DVB-SCENE%20Issue%2016%20Final.
pdf
>
> Perhaps you will have to replace %20 by space chars for
> the link to work :
>
http://www.dvb.org/documents/newsletters/DVB-SCENE Issue 16 Final.pdf
>
> Unfortunately, you won't find much more info on the
> subject in the document than what is in the title of
> this post...
>
> Well i guess this is not such a surprising news item,
> as the bitrate figure is already to be found in a
> Mark's Monday memo from April 2000.
Yes, that and a slightly lower coding were used in comparison tests in
the US, way back in 1999 and 2000. To achieve 19.7 Mb/s, the closest
rate to 19.39 Mb/s of 8-VSB, COFDM in a 6 MHz band uses 64-QAM, 1/16 GI,
and 3/4 FEC. Some of the comparison tests used 1/8 GI, so 18.6 Mb/s in
the 6 MHZ band. At that time, 1st generation receivers, this was robust
enough to beat 8-VSB in indoor tests and when close to the transmitter,
but the results far from the transmitter were not so different, or 8-VSB
had the edge (a 4 dB advantage).
http://www.tvtechnology.com/features/On-RF/dl_8VSB_vs_cofdm_part1.shtml
> However, it is interesting to see it used again in the
> context of a latin America demo, where people are not
> likely to try too dangerous parameter settings.
Well of course, to the two organizations, this is important. Both ATSC
and DVB have an interest in promoting their standard as much as
possible.
The broadcasters might have a preference for DVB-T, if they want to use
DVB-H to transmit to handheld devices on the same frequency allocation
they use for DTT. Even though this will likely not lead to very good
coverage. And also, that preference might be mitigated by the reduced
coverage area of their DTT signal, at equal power and spectral
efficiency.
But as far as I'm concerned, neither CE vendors nor consumers should
care. Except that, of course, a shift to DVB-T in the US now would be a
perfect excuse to either delay the end of the transition for another 10
years, or perhaps to scrap OTA TV altogether. Now that good solutions
exist for 8-VSB receiver designs, I just can't see why CE vendors or
consumers need to fight the battle for the standards organizations.
Bert
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