[opendtv] Which Modulation Would You Choose on a really bad day?
- From: "Stephen W. Long" <longsw@xxxxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Sun, 17 Sep 2006 20:27:20 -0400
It might be useful to restate why, in my official capacity, I ever even
cared about DTV Modulation. For me and my organization it was simple - when
you need to get data bits to the American public in times of crisis, which
modulation system would yield the best balance of signal receivability,
commercial product viability, and data rate. The largest reason I became a
supporter of the DVB version of COFDM was the fact that all receivers had
the ability to accept all defined transmission modes. So for routine daily
business, markets could maximize data rate to deliver HDTV and one or two
sub channels. When the community (or Nation) was having a bad day, the
transmitter sites could seamlessly switch into the lower data rate, but very
robust transmission mode, allowing signals to punch through, even in the
face of poor reception conditions (like major weather events). This ability
to have a robust mode, to support mobile and emergency communications needs,
was never even considered by the 8VSB crowd.
So my question remains today, as it did nearly nine years ago now - will
8VSB support the communications needs of our citizens when they need it
most. If I can not receive 8VSB today, with a newest generation not so
miracle chip, when I live only 20 miles from the transmitters, what will
happen on a worst possible day, when people are hiding in their basements?
I had to hide in my basement when a tornado passed within 1 mile of my
house, and my wife and I watched the progress of the tornado on my local
news station, seeing the radar, using a battery capable TV set, using its
built in whip antenna. We got an acceptable analog picture, even in the
basement.
8VSB does NOT replicate the receivability of NTSC. Until it does, it
remains the wrong choice for the NTSC replacement. The only question
remaining in my mind is, who is going to have to clean up the mess after the
analog switch over, when everyone starts discovering the hard way that 8VSB
can not be received by simple indoor antennas in challenging but realistic
echo environments. God help the poor soles working on the TV station
switchboards in the days after switchover. I got started in the TV business
34 years ago when I manned the night switchboard at my home town NBC
affiliate station. If we went off the air, my evening was a living hell.
We actually would lock the doors at night because we had had irate viewers
drive by the station to cuss out out.
Here is the true best question to ask all of those on this list - if their
families lives depended on receiving information (or having their fire
department receive information) using DTV transmission facilities, which
modulation would you pick - 8VSB which works poorly when it works at all, or
a flexible modulation standard that can be tuned to punch through the worst
conditions to be received my moving vehicles moving at speed on a Las Vegas
highway (any of you remember that NAB experience)?
Enough for now. Justice will out when analog is cut off. Let's see who is
standing at the end of the game, not just in the middle of the game.
Stephen
-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx
[mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of Frank Eory
Sent: Sunday, September 17, 2006 4:04 PM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: 20060912 Twang's Tuesday Tribune (Mark's Monday
Memo)
>
>
>I have been quiet a long time on this list, but have to add a comment here.
>I just bought an integrated 32 LCDTV, HDTV, ATSC receiver. The digital
>reception at my house is AWFUL - I have tried using three different indoor
>antennas and I can only receive ONE digital TV channel. I live 20 miles
LOS
>from the transmitters in DC. I can reliably receive multiple analog
signals
>(no low band VHF, but the high band and UHF are fine). I have a roof
>mounted antenna, which significantly improves my analog reception, but does
>nothing to improve digital reception - the reflections kill effective
>digital reception. The new TV has power meters which helps one point the
>indoor antenna to get a signal. I can get reasonable (green) signal
>strength, but the tuner will not lock up the signal - too much echo for
this
>newest generation receiver chip to handle. This has been the case with
>EVERY 8VSB receiver tried in my house.
>
>8VSB remains crap. It has become clearer to me over the years that 8VSB
was
>chosen to let OTA TV die - the FCC wants people to move over to satellite
>and cable so that the OTA frequencies can be sold or used for ground mobile
>applications.
>
>It will be delicious to watch the powers that be melt down in the days
after
>the cut off of analog.
>
>We had a chance to do something right (select COFDM) for the nation, and
>vested interests blew it for the rest of us.
>
>When it all melts down and people start having hearings on what went wrong,
>I plan to be on the witness list, I will volunteer to head the committee
>that drafts a new set of specifications for advanced television for our
>nation.
>
>Stephen Long
>
By the time it all melts down it won't matter. OTA broadcasting gets
more marginalized every day, and as new forms of distribution gain
acceptance, OTA becomes increasingly irrelevant -- whether the
modulation works or not. "Wireless TV" will be something intended only
for portable devices. It won't be transmitted or received on the FCC's
allocated DTV frequencies and the modulation won't be 8-VSB. Of course,
it won't be free either.
-- Frank
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