From: "Eric Adler" <eaptech@gmail.com>
The view from my side, as both a broadcaster and a consumer of both
broadcast and 'webcast' content:
My own comments were, and are, from the outside, following along
cause I'll have to deal with it after they make the choices.
From what I've been led to understand in my time in broadcast*, the
decision wasn't made because of power costs but because they (the Grand
Alliance and the FCC) believed that 8VSB would work better over the US
both due to terrain and propagation differences and due to our markets of
television transmitters and need to place co-channel (same frequency)
transmitters relatively nearby with minimal interference.
Indeed.
The impression I acquired at the time was that that was the publicly promulgated
reason, but the real one was that the people who had to pay the power
bills were putting their foot down.
Some argue
the (C)OFDM would have been a better choice even taking those things into
account. Which should have been chosen based on what criteria is a
long discussion in and of itself but we've got 8VSB (at least for now).
As for the mobile thing, I don't know if anyone had thought that far
ahead.
Yup. There was a substantial amount of screaming from the engineering
community, *precisely on this point*: 8VSB was *substantially* harder to
receive, enough so that it wouldn't be practical to receive it mobil-ly at
all, while COFDM wasn't bad at on on mobile receivers.
As has been the case in nearly every such argument I can remember in the
last 40 years, the engineers lost to the money men, and now all we can
do is say "I toldja so". But they were, in fact, told so. TTBOMK.
It seems silly now since I had a 2" rear-projection portable NTSC
TV that was made in the mid-to-late 1980s (Sony Watchman) and now they
are trying to 'solve' the mobile delivery 'problem'. ATSC M/H adds a lot
of error correction as well as 'training data' to make the M/H stream
'easy' to detect and decode, even with Doppler and multipath effects (see
ATSC A/153 part 2 for detail) - this reduces the data rate available for
the 'main' (A/53) data significantly and does not create nearly as much
available for the M/H (A/153) data. This sounds even sillier when you
realize that ATSC standard A/49, first published in 1993, was a "Ghost
Canceling Reference Signal for NTSC" (ghosting on NTSC is a symptom of
multipath).
Yeah.
As for 'webcasting' replacing RF broadcasting, I think we're a ways out if
it will even ever happen in the general case yet alone every case. RF
broadcast is very efficient, as previously mentioned. As a broadcaster, I
push 19.393 Mbps of content 'into the air' for everyone around to receive
at once. As a consumer, I have four tuners attached to what amounts to
a few pieces of wire and I can receive roughly 80 Mbit of non-blocking
data 'through the air'. My ISP provides me a downlink speed of roughly 10
Mbps. If I were in a larger market, I'd be able to receive even more
data (non-blocking with more tuners or blocking from my POV if I didn't
have enough tuners for every channel); even if the ISP provided downlink
speeds scaled up similarly, there would be much more data available 'through
the air'. The people who live near me have the opportunity to receive that
same 80 Mbit of data without any transit costs.
Yupperoni.
Can CDNs replace some of what is now broadcast? Likely. By reducing data
rates (with better compression technologies as well as simply compressing
more) and providing content that viewers want, they could (Netflix and
others are already doing this with some content). There is, of course,
a lingering societal question about "shared viewing experiences" for
shows having set delivery schedules by broadcast.
And, quite aside from broadcast networks protecting the ad revenues
of their contracted affiliates -- the primary reason for most of the
(from an engineering standpoint) stupidity surrounding the intersection
of broadcasting and new technology -- social networking is beginning
to drive this aspect, to the point where the Golden Globes stopped
tape-delaying the west coast broadcast so those viewers didn't get
spoiled on twitter.
Live content and local
content, however, will still be (in my opinion) best served by RF broadcast
for some time to come due to both the inherent efficiencies in the
system and the ease of localization for end-users.
You bet.
* The ATSC Digital Television Standard (A/53) was developed, documented,
and formalized from the late 1980s through the mid 1990s (A/53 Part 1,
Annex A describes the history). I wasn't working in television until
2000 or so and I wasn't doing television broadcast-related work until 2008.
My production history started in 1983, though with a few years exception,
I didn't have much direct connection with the transport; I was merely an
(informed) observer.
Thanks for your views, Eric.
Cheers,
-- jra
