I think the FEC is part of the standard, so changing it probably will change the standard.
In any event the best FEC in the world won't deliver more than 100% of the channel capacity. Meanwhile the channel capacity is more or less the number of bits you send but adjusted downward for the error rate (before error correction). So if the (pre-FEC) error rate is very high under multipath conditions then there is a limit to how much you can fix things with FEC, even if it weren't hindered by the requirement to not error correct over very long sequences because nobody will tolerate the extra delay.
Certainly good FEC is essential but it alone is not a silver bullet. You have to start with a reasonably low error rate. And if you have bursts of high error rates that span longer than your error correction buffer size then you will still have dropouts during those periods.
- Tom Bob Miller wrote:
Do you mean not changing the transmission standard or not changing the receivers? Could this better FEC be made to work with all legacy receivers? The question always has been legacy receivers. If they are made obsolete by any change are we not in affect changing the transmission standard? And if so shouldn't we then vet all the latest and greatest modulations and codecs? If anyone wants to see such a combination we probably could arrange that in California at the moment. With enough interest such a demonstration could include DVB-T2 as well as CDMB-TH or DMB-TH or whatever they are calling it this week. http://www.itechnews.net/tag/cmmb/ Bob Miller On Tue, Sep 9, 2008 at 11:57 AM, Manfredi, Albert E <albert.e.manfredi@xxxxxxxxxx> wrote:----------------------------------------------------------------------John Shutt wrote:With the number of viewer complaints I've been fielding lately, and judging by the results of in-home visits, I agree.Shucks, John. Half full/half empty. As I read the article, it was describing a big non-event. They got 104 calls from those who rely on OTA TV, out of 13,000 to 15,000 households that had still been using analog OTA. And as stated, some of those merely had to do a channel scan (probably that accounts for many who "couldn't find a signal"?). Others didn't know how to plug in the set. Maybe some needed to pay attention to the antenna. (May some were just lonely so they had an excuse to talk to someone.) Not too much to complain about. It would be nice to see how those 41 percent who "couldn't find a signal" were accommodated. Did you say that in most cases of unavailable signal, the Zenith CECB fixed the problem, in your experience with trouble calls? Can you give us a feel for what the bulk of problems you're dealing with are? But sure, I too would favor more robustness. The effect that better FEC has, as shown by those DVB-T2 viewgraphs, is where I'd be looking first, especially because there's some gain to be had without changing the transmission standard. 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.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.
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