[opendtv] Re: Which Modulation Would You Choose on a really bad day?
- From: "Stephen W. Long" <longsw@xxxxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Sat, 23 Sep 2006 10:13:09 -0400
Ian,
From this description below, can I assume that organizations here in the USA
could purchase Australian DVB-T receivers, and enlightened broadcasters that
wanted to test COFDM receipt ion characteristics, doing real world tests,
with real world receivers, could perform such tests? As I understand the
exciter function in a digital transmitter, a broadcaster could change the
modulation type (8VSB or COFDM) with a simple component swap-out.
Back in 2001, when a coalition of the willing jointly sponsored some tests
for COFDM data transmissions in adverse environments, a difficult problem
was (at the time) getting consumer grade DVB-T receivers that would work
with 6MHz signals. We found early production models and raced them into
service, but they did not do HD.
It sounds like all of the species arguments about DVB-T receivers not doing
HD, not doing 6MHz could be laid to rest
One of the most enlightened compromises proposed at the height of the
earliest and ugliest days of 8VSB roll out, was to have dual modulation,
multi-format receivers. If a receiver was going to do 8VSB OTA and 16 VSB
(?) over cable, building an integrated receiver that added COFDM was
straight forward. Given the mass production scale of DVB-T receivers now,
such a design would have been an insurance policy for the Nation - we people
come to their senses and realize how difficult it is to receive 8VSB in
urban environments, a different modulation system could be switched on.
Does anyone know of a combo receiver that does 6, 7, 8 MHz, does ATSC and
DVB-T, does HD and down converted SD?
What would be fascinating is to see what such a receiver would cost in mass
numbers. Maybe the USA subsidized receivers should have such an ALL MODE
receiver capability - we buy a little insurance with our Tax dollars.
Stephen
-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx
[mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of Ian Mackenzie
Sent: Saturday, September 23, 2006 1:39 AM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: Which Modulation Would You Choose on a really bad
day?
As you well know because of border issues Mexico and Canada had no
choice
in selecting a DTV modulation method.
Any settop HD in Australia will work in any other DVB country in HD and
SD.
(They have an SD downconverted output as well as the HD outputs)
This is what is called a STANDARD. Boxes work on 6,7 and 8 Mhz as its
easier
for the chipmakers to include this function in their chipsets and with
DVB
systems it's basically only a clock frequency change anyway.
I don't know what you are on about relating to audio, Australian DTV
uses
MPEG-2 just like any other DVB-T system does. AC-3 is optional in
additional
To MPEG.
I can (and have) bought a dual tuner diversity mobile DTV mobile
receiver
on the internet from Germany. It works perfectly here in Australia.
The big joke is that DBS worldwide uses DVB including the USA systems.
OK not COFDM but the DVB-S system used is all part of the integrated
DVB solution of DVB-T, DVB-S, DVB-C and DVB-H.
-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx]
On Behalf Of John Willkie
Sent: Saturday, 23 September 2006 6:39 AM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: Which Modulation Would You Choose on a really bad
day?
So, you now have an excuse? a rationalization?
Why is it obvious that Mexico and Canada have to use the U.S. system?
Does Mexico have to have the same region coding for DVDs that the U.S.
has? (It doesn't)
Does Canada have to have the same DBS system that the U.S. uses? (They
don't, and have made it illegal for Canadian systems to be shipped to
the U.S. and vice-versa.)
Australia is definitely a COFDM outlyer. By the way, if I buy an
Australia HDTV system, will it receive HDTV when I move it to the U.K?
Will it be able to process MPEG-2 audio? Australia, to draw the
important distinction, is the only COFDM country where the government
doesn't distort the media marketplace, or where the privatization of
media happened in the recent past.
Yes, COFDM works in mobile environments. So will Super-8 film. It's
just unlikely to be a profitable service in the near or medium term
because eyeballs away from home are seldom free to watch a video screen
for more than a few minutes per day. This is not to dis mobile digital
media (audio and data services) just the stupid video-centric ones.
Ah, HDTV on satelite. That's the canard. There's more HDTV on
satellite on either of the U.S. DBS systems than in the rest of the
world. I haven't checked Sky Mexico recently, but they can't be far
behind. Nor StarExpress and ExpressVu in Canada.
If I'm not mistaken, there's more people in S. Korea watching HDTV via
IP networks than watch Japanese and European HDTV satellite services.
It's all about free media markets, not modulation. Nobody watches
modulation: they watch content, and the wider and deeper the selections,
the better. The menu isn't very deep or wide in countries with less
than free media environments.
So, to sum it up. Mexico, a third world country where only a single
city (Monterrey) arguably has drinkable water on tap, offers more
terrestrial HDTV services than all COFDM countries save Australia.
Combined.
COFDM -- at least for the moment -- equals the third world of
terrestrial digital media. Or worse.
John Willkie
P.S. I don't particularly care which modulation is used. I look for
deep and wide selections, and sustainable systems.
-----Original Message-----
>From: Ian Mackenzie <ian@xxxxxxxxxxxxxxxxx>
>Sent: Sep 22, 2006 2:45 AM
>To: opendtv@xxxxxxxxxxxxx
>Subject: [opendtv] Re: Which Modulation Would You Choose on a really
bad day?
>
>Obviously Mexico and Canada have to use whatever the US chooses.
>
>Basically the USA and S.Korea are the
>only takers for ATSC
>
>As to HD there are 5 networks with over 80 Stations transmitting full
>time HD in Australia.
>They have been for some time and more are coming On line all the time.
>(not counting translators, repeaters and gap-fillers).
>
>HD on satellite in Japan and Europe is also something That's been
>operating for some time.
>
>One doesn't have to give excuses as to whether COFDM will work in
>mobile or handheld, city, suburban or urban environments, it just does.
>
>-----Original Message-----
>From: opendtv-bounce@xxxxxxxxxxxxx
>[mailto:opendtv-bounce@xxxxxxxxxxxxx]
>On Behalf Of John Willkie
>Sent: Friday, 22 September 2006 2:28 PM
>To: opendtv@xxxxxxxxxxxxx
>Subject: [opendtv] Re: Which Modulation Would You Choose on a really
>bad day?
>
>falta: (WRONG)
>
>ATSC countries (actually transmitting, as we speak) U.S.A; Canada
>Mexico, S. Korea. NO COFDM. Taiwan (not exactly a country) is an ATSC
>country, but I don't think they're doing much 8-VSB there.
>
>That's -- depending on how you count -- four or five ATSC countries.
>With the exception of S. Korea and Taiwan, they're also countries where
>the government doesn't control most (or everything) in media.
>
>not a mere coincidence, I'd say.
>
>There are more commercial HDTV stations operating in Tijuana, Mexico
>today than there will be testing facilities in Paris in short order.
>More HDTV stations in Tijuana, Mexico than there are in all of Europe.
>That is, there are two, with a third in short order. And, they've only
>just begun on the 18 year transition to digital in Mexico. (There are
>other DTV stations in Mexico.)
>
>John Willkie
>
>-----Original Message-----
>>From: Ian Mackenzie <ian@xxxxxxxxxxxxxxxxx>
>>Sent: Sep 20, 2006 8:29 PM
>>To: opendtv@xxxxxxxxxxxxx
>>Subject: [opendtv] Re: Which Modulation Would You Choose on a really
>bad day?
>>
>>If I wasn't having a bad day before choosing ATSC I Certainly would be
>>afterwards.
>>
>>The whole world except 2 countries uses COFDM in one form or another
>>for DTT.
>>
>>Can't you see who's out of step Doug?
>>
>>-----Original Message-----
>>From: opendtv-bounce@xxxxxxxxxxxxx
>>[mailto:opendtv-bounce@xxxxxxxxxxxxx]
>>On Behalf Of Doug McDonald
>>Sent: Thursday, 21 September 2006 7:06 AM
>>To: opendtv@xxxxxxxxxxxxx
>>Subject: [opendtv] Re: Which Modulation Would You Choose on a really
>>bad day?
>>
>>To reply to the subject line,
>>
>>I would choose whichever system gave the most bits at with the least
>>problems with digital into digital co-channel and adjacent channel
>>interference.
>>
>>This chooses ATSC over DVB-T.
>>
>>The reason is simple. A really bad day is one in which tropo ducting
>>is
>
>>strong. This fairly frequently causes, where I live, bad adjacent
>>channel interference and more rarely co-channel. The 3 dB interference
>>advantage of ATSC can really help.
>>
>>Doug McDonald
>>
>>
>>
>>
>>
>>
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>
>
>
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