[opendtv] Re: Mobile TV: $2 Billion in Ad Buys
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Mon, 21 Apr 2008 11:07:28 -0400
Craig Birkmaier wrote:
> Bert has long held that it is important to have long term
> certainty about the target receiver for any broadcast system.
> In this he has been supported by the ATSC and broadcast
> community. Bottom line:
>
> "We cannot have ANY receiver go black for any ATSC broadcast
> mode."
You continue to misunderstand.
Of course a broadcast system has to rely on the compatibility of
receivers, and of course it helps to have long term stability. But
enhancements can be introduced, and always have been, preferably
backward compatible with legacy receivers. Looking back always helps.
FM was introduced, was it not? And it was not compatible with AM. FM
stereo was introduced too, but it was backward compatible with FM mono
receivers. So it is, and always has been, a mixed bag.
Gratuitous ungrades, just for the sake of giving trade journalists
something to write about, are of course to be avoided. That's
self-evident.
> Imagine the public reaction when the millions of consumers,
> who have been forced to buy an ATSC receiver in their big new
> HD capable display, learn that they will need a new STB to
> receive the enhanced ATSC broadcasts...
If the new feature is something they want, they will go for it. If not,
they won't. You make a far bigger deal of this "forced to buy" than I'm
sure the vast majority of consumers makes. The cost to the consumer is
noise level, Craig. Consumers finally did accept FM, did they not?
Because broadcasters and the CE industry made it worth their while. Much
higher fidelity sound, stereo, and the price was right. When the time
came to upgrade, they naturally went for FM.
> But the DVB is moving on. DVB-T2 may be deployed in the U.K. by
> the time any meaningful MPH deployment takes place here in the U.S.
Again, you misunderstand. We don't know exactly what DVB-T2 consists of.
At least, I haven't seen anything explicit, other than the 32K mode and
MIMO scheme, which might be one of the candidates.
This is a separate discussion from MPH, or any high robustness scheme
for handheld devices. You seem to be confusing the two, even though you
have no information on what DVB-T2 will really be.
> And there there is MIMO and the possibility of allowing DVB-T2 to
> deliver upwards of 40 Mbps in an 8 MHz channel.
>
> So much for Bert's spectral efficiency arguments.
Yes, Craig, at close to 24 dB of C/N. You really do need to keep all
these facts together.
The MIMO scheme was measured to work, with certain problem areas, at
about 24 dB of C/N. The Shannon limit for 44 Mb/s in a 7.4 MHz channel
is 17.8 dB of C/N.
The Shannon limit for 8T-VSB is 10.47 dB of C/N, and actual results are
consistently in the 15.something dB range. So those are the important
points to keep in mind.
In order to ensure that the MIMO scheme can in fact provide twice the
bit rate, you are almost forced into an SFN configuration, for the
typical market. So that means greater costs for US broadcasters, who
already now seem happy to let the MVPDs do their heavy lifting for them.
So how exactly does this help? There is no free lunch, Craig.
Honestly, if you can maintain a more positive attitude with a new
microbrew, that would be great!
Bert
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