John, It's hard to make a comparison of bit rates without knowing whether apples are being compared with apples. The details you provide below are a good start, but for one thing, we don't have the equivalent for E-VSB. Anyway, what you provided agrees with ETSI EN 300 744. In order to achieve 13.6 Mb/s, the LP channel has to go to a short guard interval (1/32) and has to increase its C/N margin (Gaussian channel) to close to 20 dB, if you want to give the HP channel the 10 dB figure. If you recall, the non-HM 20 Mb/s channel was good for 18 dB of C/N margin, according to the same source. So what if you wanted the LP channel to remain as robust as it was before, in a non-HM channel? In other words, make the LP channel good for 18 dB of C/N margin (Gaussian), then see what kind of bit rate you're talking about? There are a zillion different possibilities with COFDM, but to give your HP channel the 10 dB margin, you'd have to reduce the bit rate of the LP channel to about 11.7 Mb/s. But again, we don't have the comparative numbers for E-VSB, so it's pointless to split hairs here. I don't think the difference in bit rates is valid as a comparison point, yet. They're close enough as to be a wash, at this point. Bert > -----Original Message----- > From: John Shutt [mailto:shuttj@xxxxxxxxx] > Sent: Monday, April 12, 2004 10:55 AM > To: opendtv@xxxxxxxxxxxxx > Subject: [opendtv] Re: PR: Enhanced AC-3 Audio Specifications Serve > Multiple Applications >=20 >=20 > Terry, >=20 > "Nebulous"? >=20 > Am I wrong about the HP to LP data ratio with E-VSB? Am I=20 > wrong about the > demos at the 2000 NAB? >=20 > For the modes used at the 2000 NAB demo, see: >=20 > <http://www.dvb.org/documents/white-papers/WP01%20(DVB-T%20Hie > rarchical).pdf > > >=20 > Modulation: 64 QAM/QPSK > Guard Interval 1/32 > LP code rate 3/4 > HP code rate 1/2 > LP bit rate 13.6 Mbps > HP bit rate 4.5 Mbps > LP Gaussian noise performance 19.6 dB > SD Gaussian noise performance 10 dB (this number is on the=20 > document I point > to on the link above, but was not on the original March 2000=20 > document which > I still have.) >=20 > However, it is a moot point, Terry, as E-VSB is as dead in=20 > the United States > as DVB-T is no matter how well it may perform. >=20 > Cheers, >=20 > John Shutt >=20 > ----- Original Message -----=20 > From: "Terry Harvey" <tjharvey@xxxxxxx> > To: <opendtv@xxxxxxxxxxxxx>; <opendtv@xxxxxxxxxxxxx> > Sent: Saturday, April 10, 2004 2:24 AM > Subject: [opendtv] Re: PR: Enhanced AC-3 Audio Specifications=20 > Serve Multiple > Applications >=20 >=20 > > John, > > > > Your comparison between DVB-hierarchal modulation and E-VSB=20 > is nebulous. > > You have no quantitative data to support your assertion. > > > > I recall the NAB demonstration. I was impressed but show me=20 > the direct C/N > > ratio, BERs and bandwidths employed for a direct=20 > comparison. I suspect > that > > you will find that E-VSB is more robust under the=20 > comparison you describe. > > > > Terry Harvey >=20 > =20 > =20 > ---------------------------------------------------------------------- > You can UNSUBSCRIBE from the OpenDTV list in two ways: >=20 > - Using the UNSUBSCRIBE command in your user configuration=20 > settings at FreeLists.org=20 >=20 > - By sending a message to: opendtv-request@xxxxxxxxxxxxx with=20 > the word unsubscribe in the subject line. >=20 >=20 ---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways: - Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word unsubscribe in the subject line.