----- Original Message ----- From: "Albert Manfredi" <albert.e.manfredi@xxxxxxxxxx>
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.
I never claimed differently. However, a broadcaster gets handheld receivability with zero loss of bits. If the mobile market is important enough, they can combine DVB-H time slicing with HM COFDM or simply crank down the bitrate a bit. In every case, the overall bitrate hit is lower than with any ATSC proposal for mobile-portable that I have seen.
But to do that with 8T-VSB is straightforward. Assuming anyone cared.
And in that mode, ATSC would be no more robust than it is currently for mobile, which is to say almost no mobile reception at all (but you'd be saving battery power by time slicing the indecipherable bits.)
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.
The only thing that the 2000 demo didn't meet was the FCC mask. The robust stream far exceeded any FCC planning factor with a Gaussian noise figure of 10 dB, if it really mattered.
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.
ATSC has more than it's share of "fancy tools" that will never be used. Try broadcasting a program with an Music + Effects channel and a Dialog channel, then see how long it takes your phone to ring with angry viewers who can't hear the complete program audio.
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.
Or one could more easily aruge that radios in cars are in such high demand, that they are "automatically" included in cars because it is expected.
Do you seriously think that if car manufacturers stopped offering radios that people would shrug and say "oh well, didn't need the thing anyway"?
The advantage of the OEM radio is that the car maker can integrate it into the navigation system, or like in my vehicle, integrate volume and tuning buttons into the steering wheel. Aftermarket radios have a much harder time doing this.
John ---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways:- Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org
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