[opendtv] Re: Demand for free DTV rising in Australia
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Fri, 22 Jun 2007 17:04:47 -0400
John Shutt wrote:
> Margins for HM-COFDM: 19.6 dB and 10 dB.
> Margins for 8VSB vary with the amount of equalization requred,
> so without knowing how many eq taps are engaged, how can you
> measure S/N?.
You stated that you had 14 Mb/s of regular 8-VSB and 500 Kb/s of A-VSB.
That should give you all the information you need to tell us how the C/N
margins in the wide and narrow channels compare.
How do they compare? Only then can you see whether you are paying a
higher or lower penalty for A-VSB.
> I suppose the A-VSB busses couldn't get to highway speeds on
> the Strip.
So why imply that A-VSB is unable to reach highway speeds?
This is what I'm talking about when I say chronic pessimism.
> What we are comparing is the cost in bits lost from the main
> bitstream for each bit in the robust stream. E-VSB and A-VSB
> are horrible at that,
PROVE IT! What you say is simply false. But you have to prove it to
yourself by ferreting out the information on the C/N margin comparisons.
> And what I didn't mention is that the high bitrate stream all
> by itself is receivable in the mobile mode, even if HM-COFDM
> weren't used, as demonstrated by the infamous Bob Miller
> video.
Ditto for 8-VSB, when you design a receiver with decent dynamic echo
tolerance. Did you test out 8-VSB with something that measures well,
like the Samsung Gemini or (hopefully) newer ones? Didn't you hear Frank
Eory saying he could receive 8-VSB at 60 mph with a 2nd gen receiver
Motorola made?
So obviously, it's not impossible. CE vendors can make it happen if it
matters to them.
> I still have a copy if you want to watch it. Why you refused
> to watch it is beyond me.
Who cares? How is this an issue?
Bert
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