[opendtv] Re: 20060912 Twang's Tuesday Tribune (Mark's Monday Memo)
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Fri, 15 Sep 2006 16:56:19 -0400
John Shutt wrote:
>> And for plain old long range reception, where multipath is
>> usually too weak to be an issue, 8-VSB should do better by
>> several dB. Then again, this last part was even true with
>> 1st gen 8-VSB, as Sinclair found out. Should be better now.
>
> Bert,
>
> You are completely wrong on this account, and I have proven
> it to you several times over the years. Sinclair proved that
> there was NO PRACTICAL DIFFERENCE in the far field between
> COFDM and 8-VSB in the far field, in spite of the theoretical
> differences.
John we keep going around this same circle. Every time you claim I am
COMPLETEY WRONG, so every time I have to trot out the same quote.
Perhaps I should store it in my hard drive and have it ready for next
time.
http://www.fcc.gov/Bureaus/Engineering_Technology/Documents/reports/dtvr
eprt.doc
Page 12:
"Sinclair indicates that the purpose of its 'far field,' i.e., beyond 30
miles, testing was to try to determine if a meaningful difference in
performance could be observed due to the differences between 8-VAB [sic]
and COFDM in threshold carrier-to-noise (C/N) ratio needed for
acquisition of service. It states that while there is a 4 dB difference
in the theoretical C/N performance between of the two systems in favor
of 8-VSB, the average daily calibration threshold difference between the
8-VSB and COFDM receivers was 3.28 dB and that in the field this
difference shrank to 2 dB. Sinclair suggests that this may be due to
the effect of real world impairments that add to the theoretical
'gaussian' channel values."
So, to repeat, an 3.28 dB was supposed to have been the difference,
which is a significant figure. But this shrank to 2 dB, perhaps due to
the fact that these receivers were impaired to begin with. Sinclair's
own speculation, which I would agree with.
THIS is what Sinclair concluded. Nowhere in that paragraph does it say
there's no practical difference. And that is especially true when you
read the last sentence from Sinclair.
Bert
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