John Shutt wrote: > One DVB paper I have claims a 3 dB difference between HM and > non-HM 64QAM, 3/4 FEC 1/16 GI in an 8 MHz channel. > > Another DVB paper of the same vintage claims 19.6 dB Gaussian > for the LP stream in a 6 MHz channel for the NAB 2000 HM-COFDM > demo. > > The link was to show that in the real world, 3 dB is not a > meaningful difference in reception in the far field. But I have seen the C/N margins at work with the Accurian's signal monitor, and a 3 dB difference is indeed huge. The difference in reception quality between a station squeaking in at around 15.x dB of C/N, ane one coming in just slightly higher than that, like 16 dB, is very pronounced. The monitor does bounce around, but only by fractions of a dB, when a station comes in solid. Which means, there are stations out there, like for example WMPT-DT, that are always under 19 dB of C/N, and yet I can receive them reliably. So for me, it does matter. As I showed you on numerous occasiuons, Sinclair showed a real-world difference of only 2 dB in reception in the far field, *and* speculated that possibly this was due to the other flaws in the design of those 1st gen receivers. > And again, for about the one thousanth time, it is a tradeoff, > but one that each individual broadcaster can make to best fit > their own business model, not one tradeoff made by an > engineering committee and thrust upon the world. And for the 1001st time, no one ever disputed the advantages of adjustability. But it would be nice to have that without paying a price that the FCC planning factors wouldn't accommodate, right? Bert ---------------------------------------------------------------------- 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.