So, a little early, but to maybe draw this thread to some conclusion...Do NOT use the WRAL "tests" (NOT A TEST, a demo) to reflect on what bits will be used in the (near) future. The information initially provided (to WRAL) was less than accurate, not out of malice, just lack of paying attention to 'facts' by many who were/are more interested in the indicators of performance and press coverage and NOT the technical details.
This DEMO (WRAL) was based on MPH v1 gear, not 'tweaked' to take advantage of full benefits (now) available and implemented. (background - v2 gear such as that used in the OMVC IDOV activity are most reflective of expected/proven efficiencies, and those are the ~18% for 1/4 rate and ~36% for 1/2 rate I stated earlier)
In the v1 gear used in WRAL, the actual numbers would (on the surface) reflect numbers/efficiencies far different from current v2 (the system being documented in ATSC). On top of that, the numbers used (and the coding rates attributed) are not accurate, and without a whole, long, big, and for the most part fruitless discourse, should be paid little attention. Yes, the numbers were stated. Yes, the numbers are wrong. No, this was not a TEST. Yes, this was for the 'optics' of the parties involved.
If nothing else, this (WRAL demo) and other similar activities are more of a 'gut check' and 'marketing optics' activity than 'tests'. If one does not ask the right questions, look behind the curtain, and cut through the smoke, you end up with no understanding of what was really going on...
In closing, I have seen the efficiencies stated earlier, they have been demonstrated, and best reflect 'planning' numbers.
Mark still trying to keep the sail to the wind On 8/8/2008 3:54 PM, Manfredi, Albert E wrote:
Bob Miller wrote:OH!! Then there was that thing about DVB-T not being as efficient as 8-VSB. Something about DVB-T only being capable of 18.6 Mbps while 8-VSB could handle a whopping 19.34 mbps.The problem with comparing spectral efficiency, we should always remember, is that it makes no sense at all to compare it UNLESS you include the threshold C/N ratio required for solid reception. Without the *two* numbers, you can take any position you want and rant about it. So in this case, the comparison is that with a slight drop in b/s/Hz, you are also saddled with a 3 dB increase in the required signal margin. Yes, it looks like in some modes DVB-T2 may address that issue. I'm waiting for the results with baited breath. 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.
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