*From*: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>*To*: <opendtv@xxxxxxxxxxxxx>*Date*: Thu, 9 Nov 2006 12:04:09 -0500

Tom Barry wrote: > That is, at a reasonable, typical, and equivalent (very bursty, > non-random) error rate, how many bits per second can be delivered > in how much channel bandwidth by the various methods? They are comparable, Tom. You can check for yourself, for example by comparing the A-VSB numbers in http://www.iptv.org/dtv/2006/media_pres.cfm?ses=5&id=7&Track=T (the presentation Craig pointed out yesterday) with the COFDM numbers in http://www.ttv.com.tw/TVaas/file/En300744.V1.4.1.pdf You should do this, really, otherwise you seem unable to be convinced. The short version is this: The most robust for of COFDM is QPSK, non-HM, which provides 3.7 to 4.5 Mb/s in a 6 MHz channel. (The range is caused by varying the GI.) This is 0.617 b/s/Hz to 0.75 b/s/Hz. The C/N margin needed for this varies from 3.1 to 5.4 dB (single antenna). The most robust form of A-VSB is 1/4 rate, which provides 4.85 Mb/s in a 6 MHz channel (actually 5.38 MHz channel). This is 0.808 b/s/Hz. The C/N margin needed for this is 4.5 dB C/N (single antenna) or 1.7 dB C/N (diversity antenna). Summary: in the most robust mode, COFDM provides slightly less spectral efficiency at potentially slightly higher robustness. The Shannon limit for 4.85 Mb/s in a 5.38 MHz channel is -0.615 dB of SNR. Which means that with diversity antenna, A-VSB is about 2 dB away from theoretical best. Which means, you won't get a whole lot better. I have no COFDM numbers to compare, but as I said, you won't get a whole lot better no matter what. Furthermore, if A-VSB is used in an HM-sort of situation, i.e. some A-VSB and some regular 8-VSB, then the A-VSB part of the signal is just as robust as it was in the non-HM case. This is not quite true in COFDM, though. The difference can be small in some modes, but in general, the robust channel becomes somewhat less robust when 16-QAM or 64-QAM is transmitted along with QPSK. So, please check the numbers out. They are comparable. 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.

**Follow-Ups**:**[opendtv] Re: Let the games begin***From:*Mark Schubin

**[opendtv] Re: Let the games begin***From:*Tom Barry

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