[opendtv] Re: Mobile TV: $2 Billion in Ad Buys
----- Original Message ----- From: "John Willkie" <johnwillkie@xxxxxxxxxxxxx> 



If I have been able to read through the interlineations, we are in general
agreement.

1) two-way is better that one way, and
2) mobile tv will work better if it's not just mobile video and
3) A-VSB seems to use a big overhead.


Yup, we are in violent agreement.


(my criticisms have ALWAYS been of mobile video, not mobile TV)
Judging by the number of DVD systems sold by OEM auto manufacturers, I'd say mobile video entertainment is the only segment of the mobile video market that has actually made money, since the profit is made at the time of sale.
Without doing a spreadsheet on it, devoting 11% of your transport stream to 
serve mobile audiences seems much better than the hit in going to DVB with
receiver/confusion issues (there being only one ATSC/DVB set on the market
-- at least that I've seen).
With the exception of occasionally messing with Bert, I fully appreciate it is long past the point where DVB-T is a viable alternative to ATSC in the US. The point of no return in my opinion was the FCC tuner mandate.
However, I'd rather have had the choice of sacrificing 11% of my transport stream to make the other 89% receivable by all devices mobile and fixed, rather than sacrificing 11% of my transport stream to make less than 5% of the total potential bitrate receivable by portable devices only, and not receivable at all by legacy home devices.
I believe Bob Miller's infamous demo was at around 17 Mbps. The demo is still up at www.viacel.com/bob.wmv. That reception, while far from perfect, was more than adequate for backseat viewing, and was receivable by all fixed receivers as well. No either/or choice of bitrate allocation.
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. DVB-H as implemented here in the US is slightly different, as the video resolutions are geared to handheld screens, and the carrier frequency is well outside of the US television band. (And I think the channel is narrower than 6 MHz as well.)
The other DVB-T solution for mobile reception was HM-COFDM, but that was fairly rigid in the amount of robust vs. high capacity bitrates available, but the bitrate hit vs. the number of robust bits transmitted is lower than any of the ATSC proposals I've seen.
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. If your baseline is 19.4 Mbps, That's about 1.4 Mbps of lost payload (7%) and in return you deliver 4.5 Mbps (23%) to mobile devices AND to legacy fixed devices. (All DVB-T chipsets support HM COFDM modes so legacy fixed receivers can tune the robust bits.)
However, all of that is a moot point for the US, so we're counting on your work on the ATSC committes to deliver us the best possible M/H standard.
While I was at the convention, I asked about HD Radio. As one example, the folks at C.Crane -- with two HD radio sets, none on display -- said they had 
sold very, very few.  This in the second year of a very aggressive push to
HD Radio units in advertising channels.
Strange. Our listener is very happy with his HD radio. Seriously, HD radio is at the same point that ATSC was 5 years ago. We're on a first name basis with our listeners.
HD radio is not going to take off until it is commonly offered in OEM car radios, which should happen in the next 1 to 2 years. (I'm sure availability in OEM radios was a big factor in the penetration of satellite radio.) After that, HD Radio will have all the success of AM Stereo... 

John







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