Re: Chinese choose both VSB and OFDM
- From: "David" <davey@xxxxxxxx>
- Date: Fri, 30 Jun 2006 07:15:51 -0400
"Bob Miller" <bob@xxxxxxxxxx> wrote in message
news:jwzog.11$vt2.7@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
There ADTB-T is a single carrier modulation. If it is an improvement over
8-VSB, which I think it is, that is fine by me. Anything is better than
what we have.
The US is stuck not only with 8-VSB but with MPEG2, both are inferior for
what we are trying to do in the US, broadcast HDTV. Both should be
changed. If either is changed all current receivers are obsolete so both
should be changed together.
If you are going to change codecs, say MPEG4 AVC for MPEG2, and thus make
all current receivers obsolete, you should consider ALL the improved
modulations that are now available including ISDB-T just chosen by Brazil
and therefore all of South and Central America, DMB-T/H and ADTB-T just
both chosen by China in a dual modulation or DVB-T/H used by most of the
rest of the world.
Or we can set back and wait for OTA to die in the US and the spectrum to
be auctioned off.
Oh! There is also A-VSB that is "backward" compatible with current 8-VSB
receivers with the emphasis on BACKWARD. It in truth makes all current
receivers obsolete also IMO since you can't receive the A-VSB part of the
broadcast on current receivers. That means that if a broadcaster uses
A-VSB they will have to pay 2 Mbps up front in overhead just for the
privilege. Then they have to decide how many bits to allocate from whats
left over, 17.34 Mbps, for A-VSB. If they decide on say 9 Mbps for A-VSB,
leaving 8.34 Mbps for 8-VSB, they would have a choice of delivering 1.8
Mbps, 2.25 Mbps or 3 Mbps of good video/data robustly in the A-VSB segment
depending on what mode they choose.
That is a colossal waste of either 9.2 Mbps, 8.75 Mbps or 8 Mbps out of
the 19.34 Mbps total. How are they going to deliver HD in the remainder?
And broadcasters are very excited about A-VSB. Nat Ostroff of Sinclair
says it is the only way to save OTA broadcasting. Will broadcasters use it
if it becomes available? You bet.
8-VSB/A-VSB both garbage IMO. The US should not be stuck with such.
As far as Mark Crispin talking of the need for 8-VSB for the far field.
First it is a BS. Second the Chinese version of VSB claims the same thing
and is being touted as being superior to the OFDM modulation adopted in
China.
But Chinese broadcasters have to make the choice. While receiver in China
may be built to receive both, broadcasters have to use ONE or the OTHER.
They will chose the OFDM version IMO just as I said US broadcasters would
chose COFDM if given the choice.
In fact they already are. There are 30 cities testing OFDM and only a few
testing VSB.
Bob Miller
"Do you persistently bear grudges and not forget insults or injuries?"
http://www.med.nyu.edu/psych/screens/personality.html
.
- References:
- Chinese choose both VSB and OFDM
- From: Bob Miller
- Re: Chinese choose both VSB and OFDM
- From: Mark Crispin
- Re: Chinese choose both VSB and OFDM
- From: G-squared
- Re: Chinese choose both VSB and OFDM
- From: Bob Miller
- Chinese choose both VSB and OFDM
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