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Discussion Starter #1
Accoring to an article here , the ATSC has created its first draft of enhancements to the digital broadcast standard and is now looking for volunteers to test it. Among other things the article says:


"Earlier this year, T3/S9 received ten responses to its Request for Proposals (RFP) for enhancements to ATSC transmission specifications. Based upon the responses to the RFP, ATSC T3/S9 has developed a draft set of revisions to the A/53 Standard. "


It is my understanding the testing will take many months so I don't think a final proposal will be available for some time, but this is very signficant for HDTV advocates. Remember that somf of the proposals (such as the Zenith/NxtWave system recently in the press) would give broadcasters the option of carrying a more robust signal along with the basic signal thereby giving broadcasters the ability to broadcast to mobile receivers, but at the same time making it impossible for them to carry HDTV.


IMHO we need to stay on top of these developments and keep our representatives aware that HDTV is more important than mobile or other ideas broadcasters have.
 

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Rich:


I'm surprised you are still on this after the last thread. I can see that you really fear that these proposed enhancements are going to bring an end to high definition programming on DTV stations but I can't really figure out why. In all the literature you have sited (both in this thread and the last) the only place where this remotely came up was the TV Technology article. That was a technical journalist's interpretation of the Zenith/NxtWave press release. The fact is that no one, be it Zenith, NxtWave or the ATSC, has even inferred that these enhancements will make , "it impossible for them [broadcasters] to carry HDTV." These organizations are trying to enhance the delivery of the 8-vsb bitstream to the viewer because they want sell more products.


Ultimately, it is the broadcasters who will decide how the 19.38 Mb/s bitstream is allocated. Rather than running up the fear flag regarding the proceedings on enhancements to the ATSC standard, you should be hammering those broadcasters - Fox and Sinclair come to mind immediately - who have announced that their "HDTV" format will be 480p. No one on the professional side of standards, manufacturing or broadcasting considers 480p to be an HDTV format and everyone knows what a low bitrate is required for this format. These are the people who have decided not to bring HDTV to the public. Their business model calls for revenue generation by using a majority of the bitstream for datacasting. This is why Sinclair has, and continues to push COFDM. That type of modulation is less subject to multipath and more conducive to reception by mobile platforms operating in an urban environment. [BTW - some of those in Congress have talked about taxing broadcasters who use a part of their DTV channel for purposes that do not serve the general public]


- Peter Dennant
 

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i don't think he was so off base in the last thread.


Some of the proposals did look like they could limit the video bandwidth to a size small enough that hdtv as we know it would not be possible.


while currently it looks like broadcasters will have a choice on how to divid up the bandwidth. showing hdtv or not


future enhancements tho may make hdtv not an option, at current compression, because there won't be enough useable bandwidth even if boardcasters wanted to chose hdtv..


sure who knows what will happen but the one proposal did look like bad news to me. It does seems to be speculation at this point but possible.


And a good thing to keep an eye on.


As for fox the market place someday will cuase fox to go to hdtv too as it becomes more popular, so that problem will solve it's self.


-tony
 

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I don't think he was off base either.


I can interpret the press release too. If you allocate a large percentage of the channel to a format I can't receive with my current equipment then I don't understand how anyone could figure I could still get a full HDTV signal.


But if you keep a lot of it in a compatible format so I can still receive it then I don't understand how even newer receivers in the future can get a full HDTV signal.


So if I can't get HDTV and the new boxes can't get HDTV, then who can? So what will they transmit? DOWNREZ.


- Tom
 

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Discussion Starter #5
Quote:
In all the literature you have sited (both in this thread and the last) the only place where this remotely came up was the TV Technology article. That was a technical journalist's interpretation of the Zenith/NxtWave press release. The fact is that no one, be it Zenith, NxtWave or the ATSC, has even inferred that these enhancements will make , "it impossible for them [broadcasters] to carry HDTV."
I have drawn my conclusions from several sources I haven't posted here. This was discussed considerably in the OpenDTV forum at the end of September and I have read many other discussions I can't find now. For examle television Engineer Mark Schubin recently wrote:


START OF MARK'S TEXT (sorry about the bad table formatting):

"Here are the figures from NxtWave's Table 2 (Zenith's figures are very similar):


Robust Rate ---- Data Rate for the Normal Service (Mbps) ---- Data Rate for the Robust Service (Mbps)


0 ---- 19.4 ---- 0

2 ---- 19.176 ---- 0.054

14 ---- 18.434 ---- 0.378

27 ---- 17.63 ---- 0.7317

55 ---- 15.9 ---- 1.484

78 ---- 14.475 ---- 2.1

109 --- 12.55 ---- 2.94

156 --- 9.65 ---- 4.21

234 --- 4.825 ---- 6.31

312 --- 0 ---- 8.418


For video, I think we can safely ignore most of the table. If an MPEG-1-like data rate is allocated to the robust video, there's only 15.9 Mbps remaining for HD. If a more reasonable 2.94 Mbps is allocated to robust transmission, the main channel is down to just 12.55 Mbps. Is that enough for a basketball game with current coding? If a nice (and not greedy) 4.21 Mbps is allocated to the robust transmission, the main channel drops to under 10 Mbps. "

END OF MARK'S TEXT


My conclusion (not Mark's) is that there is no room for HDTV if a reasonable bitrate is assigned to the robust channel. I don't want to give broadcasters the flexibility to control their output bitrate (which is why I was against Sinclair's proposal).


I don't consider this "running up the fear flag " since I believe I know what I am talking about and this is a very real concern. You broadcasters may disagree.
 

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Gentlemen:


If I can, let me assure you that these enhancements ARE NOT going to render HDTV obsolete. Any enhancements or modifications to the ATSC standard must work with the toolbox of formats that it was originally defined to support. Otherwise, there was no reason to define standards in the first place. There is plenty of room to support the proposed enhancements within the 19.38 Mb/s bitstream. Adopting them for HDTV broadcasts may mean broadcasters will have to give something else up (my station would have to turn off the SDTV stream operating alongside the HDTV stream) but, as I have already mentioned, that will be the decision of the management/ownership of each station or group.


As Tony mentioned, the marketplace will ultimately drive what will happen. Broadcasters, who once had a lock on the American public's viewing habits, have been loosing market share consistently over the past twenty years as competition has increased. If there is enough demand and viewing levels start to increase again, I can assure you that no one will jeopardize HDTV broadcasts - enhancements or not. Of course if the competition gets their act together and those viewership levels decline again, then broadcasters will start looking for ways to generate the profit margins that Wall Street expects of them. That's the bottom line and, as I have said before, that is what will drive what services will be available on OTA DTV stations.


- Peter Dennant
 

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Quote:
Originally posted by Rich Peterson



I have drawn my conclusions from several sources I haven't posted here. This was discussed considerably in the OpenDTV forum at the end of September and I have read many other discussions I can't find now. For examle television Engineer Mark Schubin recently wrote:


START OF MARK'S TEXT (sorry about the bad table formatting):

"Here are the figures from NxtWave's Table 2 (Zenith's figures are very similar):


Robust Rate ---- Data Rate for the Normal Service (Mbps) ---- Data Rate for the Robust Service (Mbps)


0 ---- 19.4 ---- 0

2 ---- 19.176 ---- 0.054

14 ---- 18.434 ---- 0.378

27 ---- 17.63 ---- 0.7317

55 ---- 15.9 ---- 1.484

78 ---- 14.475 ---- 2.1

109 --- 12.55 ---- 2.94

156 --- 9.65 ---- 4.21

234 --- 4.825 ---- 6.31

312 --- 0 ---- 8.418


For video, I think we can safely ignore most of the table. If an MPEG-1-like data rate is allocated to the robust video, there's only 15.9 Mbps remaining for HD. If a more reasonable 2.94 Mbps is allocated to robust transmission, the main channel is down to just 12.55 Mbps. Is that enough for a basketball game with current coding? If a nice (and not greedy) 4.21 Mbps is allocated to the robust transmission, the main channel drops to under 10 Mbps. "

END OF MARK'S TEXT


My conclusion (not Mark's) is that there is no room for HDTV if a reasonable bitrate is assigned to the robust channel. I don't want to give broadcasters the flexibility to control their output bitrate (which is why I was against Sinclair's proposal).


I don't consider this "running up the fear flag " since I believe I know what I am talking about and this is a very real concern. You broadcasters may disagree.
If you are going to go this Zentith route the only logical tradeoffs are the ones where the robust channel has enough bandwith to do something. These might be #109 with 12.55 Mbps in the non robust and 2.94 Mbps in the robust channel. Add that up and you have 15.49 Mbps. What happened to the other 3.85 Mbps? They throw it away!!!


With #156 it is 9.65 Mbps in non robust(HDTV???) and 4.21 Mbps in robust channel. Add it up and you have 13.86 Mbps. What happened to the other 5.48 Mbps? They threw them away also!!


Look at the numbers and when you talk about enough bandwidth to do something with in the robust channel the total bandwidth takes a big whack.


Where they were incensed at adopting "the world standard" because of losing .5 Meg (which wasn't even true) they are now willing to whack off from 4 to 6 Mbps of bandwidth using 8-VSB for what?


For what is the big question. I warned last year that they were going to do this, had to do this but had no idea they would be so open about it. I thought they would spring this on us at the last minute like all the other BS and outright lies they are so willing to bombard us with. You know like when William Kennard put out the reaffirmation of 8-VSB in his last hour in office last January 19th only four days after the forced vote by the broadcasters and that only four days after the release of the faked test results.


The only reason for them doing any of this is so that they can do a form of crippled mobil and datacasting. Again the very things that they threatened the other standard was capable of. Well the other system is capable of mobile and datacasting but it can also do HDTV. According to their own numbers this truncated spectrum and robust channel will not allow for HDTV with 8-VSB.


Remember these are the same folks that told us in 1999 that they had solved both dynamic and static multipath and that 8-VSB worked both mobil and fixed with chips they had in hand. This turned out to have been totally fabricated. There was simply not a shred of truth to it.


Do you think that what they tell us now will have much to do with the reality in a year or two?


We have been duped. The one year anniversary of thier latest fraud is January 11th 2002. It will be an interesting anniversary.
 

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Push and push and push to get a broadcast system so poor, most people have a $200 antenna on their roof to receive it.


The broadcasters and manufacturers fought and fought and fought to keep their broadcast system rather than consider something possibly better (this'll close this thread, heh).


4 years into HDTV and now they're backpedaling and backpedaling and backpedaling on open HDTV with 8VSB and saying, hey, maybe we should make it easier to pick up digital signals, oh, and we should copy-protect em too.


Anyone here have any hair left? If I had an HDTV, I'd have ripped it all out by now.
 

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Discussion Starter #9
Everyone needs to remember that there are other proposals being considered that improve reception but either don't reduce the usable payload at all or reduce it only a small bit. We need to push for these proposals to be accepted. Broadcasters such as Sinclair will no-doubt push for this more flexible proposal, but hopefully the majority will be as sensible as pdennent.
 

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Quote:
The strongest argument that Zenith and NxtWave mustered against the other modulation sponsored by the courageous people at Sinclair was that it was only capable of 18.64 Mbps as compared to the 19.34 Mbps of 8-VSB. That difference was supposedly crucial to HDTV being broadcast. Never mind that Sinclair demonstrated HDTV at 19.76 Mbps an even higher datarate than 8-VSB could muster.
I don't want to open what is apparently an old wound anymore than I already have but it has to be remembered that that other modulation scheme requires 8 MHz of spectrum for the 18.64 to 19.34 Mb/s datastream and would require approximately double the transmit power to cover the same area as 8-vsb. Now you can argue that the current market structure is archaic and should have been tossed out years ago but that, again, ignores the ideal for the practical. On the practical side there was little or no way to integrate a new service requiring 8 MHz of spectrum into an existing one that was based on 6 MHz channels (if we could get 8 MHz of spectrum for 8-vsb, 1080p would be obtainable!). More importantly, though, if the market structure were dissolved, the broadcasters would have never agreed to build a new television transmission infrastructure with their money because it would have fundamentally altered the 50 year old business model of the industry.


Then there is that nagging power issue: I don't know if any of you are aware of how much energy is required to run one of these IOT (Inductive Output Tube) UHF transmitters but they are expensive. At my transmission plant, it takes about 190 amps (@ 480 VAC) to run the whole site including the 45 kW NTSC transmitter. When the DTV, IOT transmitter is turned on, that goes to 500 amps! At current power rates, that additional 310 amps will cost about $10,000 per month. Now, if you talk about having to double that for the other modulation scheme, you are talking about a real budget buster with no immediate ROI (Return On Investment). Add that to the already hefty investment required to build a new channel and you have a situation where the people who invest their money into broadcast companies would have started to get skittish.


This gets to be a political discourse as opposed to technical one but these factors were a part of the consideration as to which modulation method was adopted for this country. The 8-vsb modulation method has been adopted and is being built out. It will be improved upon but those improvements will have to work within the context of the ATSC "toolbox" so that the EA's who frequent this forum and have put their money on the counter (we broadcasters appreciate you guys even if you don't think we do) will not be left high and dry when they are implemented.


- Peter Dennant
 

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I want to thank both Bob Miller & Peter Dennant for summarizing their respective thinking. I also want to remind everyone that AVS has requested we not go down the 8VSB vs. CODFM road again. So, I'm asking that this particular part of the discussion end here. Otherwise, I'll have to edit or delete further comments.


Thanks,

Ken
 

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But at least one reasonable option, using the table above, is to use #14. That would give almost 400 kbs to a robust data service, and over 18 Mbps for video services - which is more than enough for HDTV and an SDTV service (most of the time).


And, the robust signal is able to itself be used to further enhance the receivability of the entire signal - thus more people receive HDTV.


There are plusses and minuses to both of the major sets of enhancements being proposed. Lets get the testing underway, make sure that it's comprehensive, and then figure out the best way to proceed.


Tom Weber
 

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Does this new standard do anything to improve multipath problems in the non-robust channels?


- Tom
 

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As I understand it, yes. If I have this right, under the Zenith/Nxtwave proposal, the robust signals can be used to enhance receivability of the non-robust signals. Under the Broadcomm (and I think others) proposal, the training signal would be enhanced, so that more severe multipath could be recognized and dealt with.


Tom
 

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Discussion Starter #15
Quote:
If I have this right, under the Zenith/Nxtwave proposal, the robust signals can be used to enhance receivability of the non-robust signals.
I believe you are incorrect. My impression based on what I have read was that the more robust channel cannot be used to enhance the receivability of the standard signal. What evidence do you have of this?

Quote:
But at least one reasonable option, using the table above, is to use #14. That would give almost 400 kbs to a robust data service, and over 18 Mbps for video services - which is more than enough for HDTV and an SDTV service (most of the time).
Since I don't believe the robust signals can enhance receivability of the non-robust signals, this is still an unacceptable solution in my eyes. I favor other proposals that DO improve reception of the main signal.
 

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This is what I understood from a panel discussion during the IEEE/BTS* seminar in Washington in early October. Representatives from Zenith and Nxtwave were on the panel; unfortunately, these were the only proponents on the panel, so we were unable to learn much about the Broadcomm proposal other than a very brief outline.


My understanding is that if one is able to receive and decode the robust signal, one can then go back and figure out what distortions are present, and then do some processing on the non-robust signal, counteracting those distortions, thus enhance their decodability.


Tom


* Institute of Electrical and Electronics Engineers/Broacast Technology Society
 

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Thanx for the verification Tom. It was also my understanding that this was how the enhancement was supposed to operate.


- Peter Dennant
 
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