[opendtv] Re: Mobile TV: $2 Billion in Ad Buys
- From: Albert Manfredi <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Sat, 19 Apr 2008 17:43:36 -0400
John Shutt wrote:
> If I correctly understand DVB-H when applied to a DVB-T
> stream, DVB-H in and of itself doesn't incur a bitrate
> penalty to the DVB-T transport stream. It just provides a
> predictible time slice to offer related program data
> packets, so the receiver can turn on and off at regular
> intervals, saving battery power.
And in that mode, the DVB-H stream is no more robust than the main DVB-T stream.
But to do that with 8T-VSB is straightforward. Assuming anyone cared.
There are plenty of time marks in the 8T-VSB channel as is, which could be used
for this additional purpose. And they are modulated in 2-VSB. For a receiver to
use them for this on/off purpose would create almost no change to A/53. This
would be mostly an exercise in receiver design, first to switch on and off
according to some new rule (that would not affect existing receivers at all),
and next to implement a more elaborate training scheme, for example as
suggested by McDonald/Patel/Limberg.
> The DVB HM-COFDM demo at the 2000 NAB delivered
> 4.5 Mbps of robust mobile data, and about 13.5 Mbps for
> the main service, in a 6 MHz channel.
But the wide channel did not meet the FCC planning factors, i.e. 15.2 (or
thereabouts) dB of C/N for reception. You need to compare apples with apples
when making these comparisons, John.
I think that the fundamental difference between ATSC and DVB is that DVB can
afford to create any number of fancy tools, even if they end up never being
used. ATSC does not do this. ATSC worries about protecting IP and achieving ROI.
> HD radio is not going to take off until it is commonly
> offered in OEM car radios,
I think one could easily argue that point about radio in general. If radios
were not offered "automatically" in cars, as standard equipment, as of today,
IMO radio would fail here in the US.
Bert
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