[opendtv] Re: (No Date: Tue, 28 Sep 2004 10:30:37 -0400

  • From: "John Willkie" <johnwillkie@xxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Mon, 11 Oct 2004 00:23:22 -0700

Alas, the choice is not being made now, and unlike you, all the people who
made it were in their right mind.

I say that advisedly: You seem to want to fight the effects of time.
Playing an old violin, off-key, without sheet music, teacher, or talent.

I have no issue with modulation:  it's just the transmission of transport.
I will be testing my transport packets within the next week or so.  Those
same transport packets will work with 188-byte COFDM transmission as well,
although some of the tables will be removed and DVB ones added.

Also, I am in the fun situation where dynamic metadata will be required of
all US DTV stations, and they have until February 2, 2005 to implement it.
Maybe I should use the long extension cord and run down the street to test
mobile reception of video?

Here's what I have found in my very limited testing of ATSC transmission.
At my apartment, with a B2C2 tuner card in my PC, attached to 24 inches of
300 ohm lead in (as an "antenna") I get KSWB-DT (channel 19) with a signal
to noise ratio between 22 and 27 dB.  I find that if I have at least 6 dB
SNR (from other stations that are more distant and not as strong with my
jury rig) the reception is in lock.  There are stations that I cannot
receive well.  Maybe I'll try it next time with an antenna.  By spending
$20, I expect to demodulate stations 120+ miles away.  That means that it
will have cost me $200 to receive DTV signals.

So, COFDM reaches points where no humans live, and 8-VSB does not reach
areas that lack humans yet have high EMI/RFI.  This will be the death of
broadcasting, no, since nobody wants to reach humans, and all humans live in
high RF environments.

Tilt on, Bob.  You are always entertaining in a "what the ..." pained kind
of way, trying to sell right-hand drive equipment in a left-hand drive
market.



-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx
[mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of Bob Miller
Sent: Sunday, October 10, 2004 6:27 PM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: (No Date: Tue, 28 Sep 2004 10:30:37 -0400


No one in there right mind would chose 8-VSB over COFDM now, in 2000, in
1999 or five years from now. Mexico, Canada S. Korea and the US were all
political decisions IMO. The best interest of the public were not and
are not being considered.

I have done all the testing I need to do to know which is the best for
our use. How many test have you done or do you plan on doing?

As far as going deeper into the building, the old AT&T HDQTs building at
32 Avenue of the America's is a brick s**thouse. I remember one incident
when we were only broadcasting from an apartment building above the
Lincoln Tunnel with a 100 Watt antenna I was in the bowels of that
building, AT&T, on the 24th floor with cages, servers and walls all
around in the middle of the building and wanted to demonstrate our COFDM
broadcast to the building manager. I simply turned to a cement pillar
and plugged into an outlet there then realized I had no antenna. My
finger touching the antenna connector did the job which amazed me. We
had perfect reception even when I waved the receiver around, took it
behind the pillar etc.

That same building with a 5th gen receiver on the 25th floor with a dual
bow tie antenna was easily defeated at far far greater power levels even
though that receiver and antenna were virtually a few feet and one wall
from perfect line of sight to the source, The Empire State Building.

COFDM worked and could not be made to fail MUCH deeper in that building
even though we were at FAR lower power levels and a slightly farther
distance away.

BTW Hisense says that as soon as their current stock of 4th gen
receivers runs out we will see 5th gen. I have no idea what that means
time wise. They had said that they made or were going to make 400,000
4th gen receivers. I don't know how many they actually made. Will know
more about LG's plans by Wednesday.

Bob Miller

Manfredi, Albert E wrote:

>Bob Miller wrote:
>
>
>
>>The point is not that COFDM can go to a higher bitrate
>>but that at an equal or slightly higher bitrate it is
>>still more robust than 8-VSB.
>>
>>
>
>The point is, Bob, that your statement is unsubstantiated
>and non-credible. I'll bet you that if you actually did
>a test, with a 5th gen Zenith vs a current model COFDM
>receiver, you would see what I suggested. Indoors, with
>simple antenna, better dynamic echo performance for COFDM,
>and better weak signal performance from 8-VSB.
>
>Meaning, you can continue to receive a solid signal with
>8-VSB even as you go away from windows or exterior walls,
>where COFDM (64-QAM, 3/4 convolutional FEC, 1/16th GI)
>will drop the signal sooner. When severe multipath exists
>but no one is dancing in the signal path.
>
>
>
>>And from there you can dial it down to whatever datarate
>>and robustness combo you want.
>>
>>
>
>True. With the way E8-VSB is defined now, that should also
>be an option, although not at more than 3.3 b/s/Hz.
>
>
>
>>If this was a horse race and COFDM and 8-VSB were nose
>>to nose with a quarter to go yes Vive la difference but
>>in this race COFDM won yesterday and 8-VSB is still at
>>the starting gate. Why are we bothering with it at all?
>>
>>
>
>You, and some others, continue to make these tired claims
>from yesterday's information. We are where we are, and
>that won't change. The good news is that the tired old
>comparisons with the 1999 ATSC receivers are invalid and
>obsolete. You carefully mentioned "in the 2000 test" last
>time. I don't think you have a valid direct comparison
>test for the here and now.
>
>Bert
>
>
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