Archived from groups: alt.tv.tech.hdtv (
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John S. Dyson wrote:
> In article <suzXc.14613$3O3.337@newsread2.news.pas.earthlink.net>,
> Bob Miller <robmx@earthlink.net> writes:
>
>>This was from a personal trial of the receiver supplied by LG and which
>>was accompanied by the two top engineers who personally developed the
>>5th generation receiver. They admitted to studying COFDM to make this
>>happen.
>>
>
> Firstly, I know enough about 8VSB vs. COFDM to understand that the
> claim that 'studying COFDM' has almost nothing to do with the improvements
> to the 8VSB reception. The difficulties with 8VSB were/are/always were
> understood, and the solutions have little to do with COFDM techniques
> per se.
>
Well you can take that up with the LG engineers. They readily conceded
that COFDM was superior, that they relied on COFDM in working on the 5th
generation 8-VSB receiver and that there was no hope that 8-VSB would
ever match the reception of COFDM.
>
>>This is not " NEW & IMPROVED" blah blah blah." This is the real deal. It
>>is a MAJOR transforming difference. It is truly plug and play.
>>
>
> Of course, that is to be expected.
It wasn't to be expected. Without the constant irritation of COFDM LG
would have been content with 8-VSB as it is. The 5th generation
receivers would still be years away.
Nothing that I have seen about the
> new 8VSB receivers is outside of what should have been predicted.
Predicted? They flat out said all these problems including mobile
reception had been solved in 1999.
Frankly,
> I am NOT surprised, and I have told you all along that the new technology
> would help. For nay-saying, I'd seem to remember your own claims.
>
What is to be expected? That we chose a modulation that wasted six years
of time and cost many a lot of money and hassle only to arrive five
years later at a minimally acceptable receiver that still does not allow
what SHOULD HAVE BEEN EXPECTED, NO, DEMANDED of any DTV modulation,
mobile reception. Especially since it was KNOWN that such reception was
possible and indeed was being achieved by another modulation.
>
>>As I said before I was able to defeat this receiver with both dynamic
>>and static multipath, something you could not easily do with a COFDM
>>receiver, but that is not the test that I am interested in. That test is
>>simple.
>>
>
> Yes, COFDM and 8VSB (as the technologies are fully developed) will have
> different behaviors, but the differences result from tradeoffs.
There is NO TRADEOFF. Unless you mean that you give up mobile reception
for nothing or that you give up data rate for nothing or if you mean you
give up another "X" number of years while they try to get 8-VSB to work
as well at SFNs or on channel repeaters as COFDM. There is no trade off
except in the minds of those who have not seen the difference and cling
to fantasies about 8-VSB that do not exist and lies about COFDM that are
disproven daily in many countries which use COFDM at minuscule power
levels compared to 8-VSB in the US.
We are stuck with 8-VSB, it works for me and our business. But the
process and the result is something we should be ashamed of in the US.
For years foreign visitors will marvel at how backward we are in DTV as
they do now with our cell phone system. And they will cluck about how it
was done to us using our corrupt political process. They already do.
COFDM
> is a relatively old technique (and the FFT-concept schemes have been
> used in old telephone modems until the near-8VSB equivalents had taken
> over.) The COFDM-type schemes aren't really a panacea, but are very
> well developed over the years. COFDM is certainly very good for mobile.
> 8VSB has probably 10-15yrs less development than the semi-FFT type
> schemes. Even though 8VSB will eventually surpass COFDM in most-all ways
> (where it probably does better in many ways already), the mobile niche
> will be the domain of COFDM... Eventually, with infinite amounts of
> CPU, and a full development effort where there might be a more significant
> American interest, 8VSB might work out more of the mobile issues, but I
> suspect that the new 8VSB tuner will have done much of what is possible.
> With blind equalization techniques, more CPU can be helpful, there is
> probably alot of opportunity to better exploit the signal. Geesh, the
> original TV sets in general didn't receive as much of the video signal
> as they could have.
8-VSB will never surpass COFDM. 8-VSB is stuck in a relatively small
niche market called full power DTV in a few countries, the US, S. Korea,
Mexico and Canada. Very little development work will proceed on 8-VSB as
most of the world and most spectrum uses COFDM type modulation already.
Expect the broadcasters to try to change to a COFDM type modulation in a
few years after competition arises using COFDM.
(snipped)
> Mobile consumer DTV viewing really has few day-to-day real-world applications
> in the US, given probable US traffic laws and the probable criminal charges
> for driving while watching TV. (Mass transit Max Headroom blipverts and
> saturation advertising isn't a good application in the US either.) The
> only potentially useful applications in cars: entertaining children, are
> likely better implemented by DVD-type technology.
Mobile is coming in a big way. You can relegate it to the one small area
that it is dangerous in all you want, front seat in view of driver of
vehicle, but mobile DTV will be the killer application for cell phones,
PDAs, laptops, portable DTVs and a myriad of other devices in the next
few years. All of these devices can be carried into a vehicle and
misused by the driver just like a cell phone or an ice cream cone. But
mobile DTV will be pervasive very soon.
>
> Bob, I still KNOW that the killer app is bidirectional and last mile
> connectivity for true communications (not just push) (which would include
> all kinds of data, where TV would be one of the data types.) I wish that
> you would have concentrated on that, thereby avoiding the delays in
> the market caused by you and your ilk. Such a full bidirectional solution
> would have potentially justified your mobile application that would
> partially usurp HDTV. Unidirectional data in general has only one real
> killer app, and that is TV... We already have that and it works well.
You keep bringing up bi-directionality. Why? It has nothing to do with
the discussion. We are talking about DTV and reception problems of our
inferior 8-VSB modulation.
Blaming the messenger for the problem has been a timeless tradition.
Never worked. You have to fix the problem.
Your mantra of saying that pre 5th generation receivers already work and
work well can be and has been emphatically disproved by our recent test
of 5th generation receivers. When these receivers get on the market the
public will second my opinion. Many post here and elsewhere comparing
older 8-VSB receivers to 5th generation receivers will exclaim at JUST
HOW UGLY the performance of all older 8-VSB receivers are.
This would have been even more true if the public had ever been allowed
to chose between COFDM and 8-VSB receivers. Someday soon that will
happen and even 5th generation 8-VSB receivers will look ugly compared
to COFDM.
Bob Miller
>
> John
>