Stephen W. Long wrote:
> Meanwhile, I will continue to have to pay a vendor to deliver digital OTA
> television signals to my house via fiber or satellite. A suspicious
person
> might begin to think this was the objective all along.
We have been discussing these points on this list and elsewhere for many
years, with probably few productive results. But let's imagine the
possible scenario. Imagine we really do shut off analog TV in early 2009.
And everybody, just for argument, imagine there really is a possibility
that eventually a consensus is mostly reached that it really does not
seem to be working very well. I know, I know, "ATSC WORKS"! But just
for a moment, let's consider what happens if it really doesn't.
I imagine there would be grumbling, some denial, delay, and maybe a half
hearted search for the guilty. But let's imagine what happens next.
What will we/they do? What would really happen then? Say Congress
actually seemed to finally agree that it did not seem to be working.
Does anyone really have a feel or picture of the probably outcome from
that point? I don't think I do.
Does everybody just continue to put up with it as a matter or
(oft-lampooned) national pride? Do we let OTA broadcasting fade and
just declare the entire concept obsolete? Or can we let broadcasters
keep the spectrum but start using it for something else, or sell it?
Would they make a profit that way?
Once everyone in the country has fixed 100 mbps broadband with IPV6
multicasting I'm not sure of the relative value for OTA anyway except
mobile reception. But the OTA spectrum will obviously be continued to
be used for something. Anybody know what?
So, let's explore what might happen. Anybody?
- Tom
Yes, the exact point. Digital is GREAT when it WORKS. This is why is it NOT (just) about signal strength. No one on this list has ever defended the native reception characteristics of 8VSB - it is and has always been a fragile modulation system. Since the whole point of the exercise is to receive pictures and sound, a system that digitally fades out because of multi-path echoes, is not a good choice for pictures and sound reception. A minor fade out may not affect some data types, if sufficient FEC is used, but MPEG-2 long GOPS appear to be very sensitive to these 8VSB signal drop outs - video freezes and audio drop outs do not make for a good TV viewing experience. I have had to just give up on watching ATSC signals in my house - the drop outs are just too damn annoying. Conversely, I can watch analog NTSC just fine. Low VHF sucks, but high VHF and UHF are received very well with my attic antenna, and I can get acceptable pictures using indoor antennas, even in the basement of my house.
This "new" modulation discussion threat started when I bought a new 32" HDTV LCD TV for my home office. It delivers great pictures from my satellite HDTV service. I can receive exactly ONE 8VSB station with this new receiver. I have tried the attic antenna and one of the latest and greatest indoor antennas. There appears to be adequate signal strength (according to the signal strength meter in the set), but the pictures will not lock up - freeze and blocks and just crap.
To add just a little more JP4 to the fire - one of the apparent reasons 8VSB was chosen was because of its theoretical high data rate. And just why was everyone so anxious about data rate - because of the very flawed assumption of the use of 1080/30i interlace HDTV. Interlace artifacts equate to noise which equate to poor coding efficiency, which means bits are wasted. If a more rational HDTV video format is chosen, such as 720/60p, better pictures, at a lower data rate are possible. The 720/60p pictures that ESPN releases when they do Monday night OTA football are STUNNING. The 1080/30i football pictures on another network are soft and full of motion artifacts. 1080i encoders are clearly throwing away the high frequency picture components to make the signal fit in the ATSC channel.
ATSC is nothing but a collection of poor engineering choices and poor compromises. If 720/60p is your transmission video format, it would have been possible to select data rates below 14Mbps for DTV, which means a much more robust modulation system could have been chosen, to include DVB-T. When DVB-T parameters are chosen to match the ATSC data rate, it is still more robust than 8VSB.
What is particularly illuminating to me at least as to the reason why COFDM was never seriously considered by the FCC engineering staff. Over drinks one evening an engineer told me COFDM was never considered because it would take them two to three years to re-compute the adjacent market interference and power allocations. When Sinclair started doing their public tests, the staff engineers would never consider a change to COFDM because the 8VSB decision that had already been made. It was never about COFDM not being a better choice, it was about it was too inconvenient to recalculate radiation patterns and interference.
In the aftermath of the anticipated melt down when analog shuts down, during the hearings trying to find someone to blame, maybe some of the true reasons why poor decisions were made will come out. That is, if the documents have not all been shredded by then.
Meanwhile, I will continue to have to pay a vendor to deliver digital OTA television signals to my house via fiber or satellite. A suspicious person might begin to think this was the objective all along.
Stephen
-----Original Message----- From: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of negrjp Sent: Sunday, September 24, 2006 5:46 AM To: opendtv Subject: [opendtv] Re: Which Modulation Would You Choose on a really bad day?
Dear Friends,
COFDM X VSB controversy started in the same time of the creation of these systems.
In 2000 Brazil it made RF covering tests with American 6 MHz ATSC's 8VSB, European 8 MHz COFDM's DVB and 6 Japanese MHz COFDM's ISDB-T in Sao Paulo megalopolis,using broadcast transmitters in the highest tower of the city.
The Japanese system was considered best. However, this version 6MHz COFDM failed in 8% of the analyzed localities. Brazilian Scientists are testing a "solution" to solve this problem with broadcasting diversity.
When I are little boy, somebody was said that the SSB would be the system of communication of the future. Nobody said in digital communications systems, however CW is digital...
It will be that the true controversy is digital x analog?
TTFN,
Jonas from Brazil
Ian Mackenzie wrote:
As you well know because of border issues Mexico and Canada had no choice in selecting a DTV modulation method.
I don't understand why this should be the case. Especially if Canada and Mexico had opted for a 6 MHz version of DVB-T, in which case the situation would be much as it is in Europe between PAL and SECAM countries with
common
borders.
Any settop HD in Australia will work in any other DVB country in HD and SD. (They have an SD downconverted output as well as the HD outputs) This is what is called a STANDARD.
Do the Aussie STBs support H.264 HDTV? If not, they won't work in the only other DVB-T HDTV country, which is France. As to SD outputs, that's true
for
all ATSC STBs as well. They *all* have composite and S-video outputs, as
far
as I have seen, in addition to the various analog and digital HD outputs.
But all of this is much ado about nothing. I showed that Philips, STMicroelectronics, and Micronas (at least those) already have global standard reference designs, and that at least one manufacturer in the UK already *sells* two models of global standard DTT integrated receivers,
for
what seems to be competitive prices. Why all the fuss? Who cares? If DTT STBs don't sell well in the US, it is caused primarily by three factors:
(1)
the vast majority prefer cable and DBS, (2) most TV sets now come with built-in ATSC anyway, (3) broadcasters have made it so procrastinators can be perfectly happy continuing to use NTSC. Probably because they're afraid of cable or DBS backlash if they worked to make their DTT offerings more fun.
The big joke is that DBS worldwide uses DVB including the USA systems. OK not COFDM but the DVB-S system used is all part of the integrated DVB solution of DVB-T, DVB-S, DVB-C and DVB-H.
I still think this is much ado about nothing. The only significant difference between ATSC and DVB-T that creates all the pointless yelling
is
the physical layer -- 8-VSB vs COFDM. Take that away, and the rest is just the sort of obtuse silliness that broadcast standards around the world
have
always created. Whether it was different versions of NTSC, PAL, and SECAM around the world, the industry has obviously cherished its quite
deliberate
incompatibilities.
Bert
_________________________________________________________________ Be seen and heard with Windows Live Messenger and Microsoft LifeCams
http://clk.atdmt.com/MSN/go/msnnkwme0020000001msn/direct/01/?href=http://www .microsoft.com/hardware/digitalcommunication/default.mspx?locale=en-us&sourc e=hmtagline
---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways:
- Using the UNSUBSCRIBE command in your user configuration settings at
FreeLists.org
- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
unsubscribe in the subject line.
---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways:
- Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org
- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word unsubscribe in the subject line.
----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:
- Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org
- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word unsubscribe in the subject line.
-- Tom Barry trbarry@xxxxxxxxxxx Find my resume and video filters at www.trbarry.com
---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways:
- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word unsubscribe in the subject line.