The Masked Engineer: Mario Orazio
Definition's Not the D in DTV
You might not have noticed that, as time goes by, more and more
people are understanding DTV... less. There's plenty of blame to
go around, but – if I absolutely had to pick the greatest offender
– it would have to be the good old Consumer Electronics Association
– CEA – or, as I am wont to pronounce it, See-ya.
It's pretty easy to find the association’s Web site; it's
just ce.org. And I give them high marks for navigation, too. In
just a few clicks, you, too, can look up a press release that was
sent out on May 2 of this year. Here's the opener:
"Demonstrating the strong momentum in the transition to digital
television (DTV), the Consumer Electronics Association (CEA) announced
today the sale of the one-millionth DTV product sold."
Maybe the way it talks about "the sale of the... product sold"
suggests to you some double accounting. I'd be one whole heck of
a lot more willing to take them at their word if only I had some
inkling as to what the heck the association means by DTV. A few
more clicks brings you to this official definition in a See-ya press
release way back on Jan. 8, 1998 (the definition was reaffirmed
more recently):
"Digital television (DTV) — DTV is the umbrella term used
to describe the new digital television system adopted by the Federal
Communications Commission (FCC) in December 1996."
CLEAR AS MUD
That's about as clear as can be, eh? So, does that mean a million
FCC DTV receivers were sold by May 2? As they say in those (mega)
Hertz commercials, not exactly.
Here's a chunk of the opener of a press release See-ya sent out
on Halloween. It was about "... sales of digital television (DTV)
monitors and sets (monitors with integrated tuners)...."
What the heck is a DTV monitor? You can figure out easily enough
from just those words that it ain't got a tuner, but what does that
have to do with what Our Beloved Commish came up with in 1996?
My countless spies tell me that the numbers See-ya uses for DTV
monitors are based on TV displays – with or without tuners
– that can deal with H-rates of 31.5 kHz or more. That's it.
"But, Mario, first you said a monitor doesn't have a tuner, and
then you said it could!"
Obviously, you have yet to become fluent in See-ya speak. What
See-ya calls a DTV monitor could very well have what you or I or
even Aunt Eunice would call a tuner, but it doesn't have what See-ya
calls a tuner, which is an 8-VSB demodulator and MPEG-2 and AC-3
decoders.
DEFINING VISION
As for See-ya's definition of a DTV monitor, you can search all
you want to, but you will absolutely not find that 31.5 kHz figure
anywhere in any FCC rule or regulation. Ergo, it doesn't match See-ya's
own definition of DTV – but let's not let a little tidbit like
that get in the way of reporting high numbers, eh?
By the way, when See-ya adds in the numbers of what it calls "sets,"
not even the 31.5 kHz criterion holds. An ATSC-receiver/decoder-equipped
unit can do no more than 15.75 kHz and still meet See-ya's DTV definition.
"But, Mario, are you saying DTV doesn't have to be HDTV?"
Heck, yes! And that has nothing to do with See-ya. But why should
you believe me, when Our Beloved Commish put it so much better (FCC
Report MM 97-8, April 3, 1997, p.2, third paragraph)?
"The Commission will not require broadcasters to air 'high-definition'
programming...."
You don't like reports? Here's the law (Title 47, U.S. Code of
Federal Regulations, Part 73.624 Digital Television Broadcast Stations,
paragraph a):
"The DTV program service provided pursuant to this paragraph must
be at least comparable in resolution to the analog television station
programming transmitted to viewers...."
If I've taught you anything, I hope it's been not to trust ellipses
(those dots), so – if I were you – I'd look up the missing
parts. But, if I were you, I'd be too lazy – so, on account
of that, I'll just tell you they relate to simulcasting NTSC and
DTV. Believe me if you want to; spend the rest of your pitiable
life researching if you don't.
Is it time for a recap? I suppose so.
1. What See-ya calls DTV has nothing to do with what See-ya defines
as DTV.
2. What See-ya calls a DTV tuner has nothing to do with tuning.
3. DTV doesn't have to be HDTV.
VERBAL DROOL
Now try this one, from a DTV tutorial published on Nov. 18:
"Do I need a special television set?
"Not yet. Your standard TV will receive digital television provided
you have a set-top decoder and a satellite dish or a cable connection."
Does that sound to you like the verbal drool of someone whacked-out
on drugs? Methinks it's accurate enough. It was published in the
New Zealand Herald, in a country where DTV ain't yet terrestrially
broadcast.
Hey, why not? Our Beloved Commish's DTV uses MPEG-2 encoding.
DISH Network satellite signals use MPEG-2 encoding. Time Warner
Cable's DTV package uses MPEG-2 encoding. At home, what's the difference?
Well, now, Nellie the Neuron tells me there is a difference. If
you have a cable hookup, it's a pretty safe bet decodable signals
will come out of it. If you have line-of-sight to a satellite, likewise
from your downconverter. But terrestrial broadcast DTV reception's
still kind of hit-or-miss, and I ain't just talking about ATSC or
8-VSB.
In non-ATSC countries, the issue might just be power level. Here
in the good old U.S.A., the ATSC is chewing over how to modify that
standard Our Beloved Commish adopted so as to allow "enhanced" (pronounced
more-reliable) modes of transmission.
BITS IS BITS
"But, Mario, if the reception is reliable, then DTV is better
than analog, isn't it?"
I give up. What's the answer?
Oh – you didn't mean it to be a riddle? Well, I still can't
answer it.
Suppose all the bits make it to the MPEG-2 decoder. Just how many
bits is that?
Our Beloved Commish says a DTV channel carries 19.39 Mbps, but
nowhere do the rules say how many of those bits need to be devoted
to a video signal. I'd say SDTV at 18 Mbps should look pretty good.
Color bars at 0.5 Mbps should look pretty good, too. But a basketball
game at 0.5 Mbps won't.
In its infinite wisdom, Our Beloved Commish specified a minimum
resolution for broadcast DTV video: "at least comparable in resolution
to the analog television station programming transmitted to viewers."
There ain't any such spec for digital satellite or cable, and they
sometimes look it. Can you say 2:1:1?
Maybe that's one of the reasons not so many folks have been going
for digital cable. Maybe it's the price. Whatever it is, if you're
a cable-channel programmer, you'd sure as heck rather be analog
than digital.
Back in November, the Oxygen channel announced a deal. Time Warner
Cable of New York City – one cable operator, not even covering
the whole city – agreed to move Oxygen, which they were already
carrying, from its DTV tier down to an analog tier. It's not even
the system's lowest analog tier. But that one little move from digital
to analog on one cable system is giving Oxygen an extra million
homes.
"But, Mario, who cares about cable and satellite programming?
What about broadcast DTV?"
What about it? There ain't a country on earth where it's holding
its own against digital cable and satellite yet, and every time
someone tries to fix one problem with it, another pops up.
CORE VALUES
Here's one that's really rich. Our Beloved Commish wants to sell
off the non-core TV channels. They're the ones above 51 (which means
the core has a four-octave range, which is a story for another time).
So, Our Beloved Commish comes up with a deal. NTSC stations outside
the core with DTV allocations inside the core can vacate the NTSC
channel, but broadcast NTSC from the DTV channel? Get it?
You might, even if you don't want to. The reason so many DTV channels
got to be stuck into the already crowded TV spectrum is that they
were meant to carry – all together now – DTV. DTV-into-NTSC
interference ain't so bad. NTSC-into-NTSC interference is one whole
heck of a lot worse, but that's what we'll get if Our Befuddled
Commish allows NTSC operation on DTV allocations.
Digital means never having to think about quality.
Mario Orazio is the pseudonym of a well-known television engineer
who wishes to remain anonymous. Send your questions or comments
to him c/o TV Technology. Or drop him a note on e-mail Mario_Orazio@imaspub.com.
|
