[opendtv] Re: DVB Standard
- From: tsmith@xxxxxxxxxxxxx
- To: opendtv@xxxxxxxxxxxxx
- Date: Thu, 27 Oct 2005 12:43:18 +1100
Dan
"...adopted by the U.K. and Europe than North"
and Australia.
DVB and ATSC are similar in that both are based on MPEG-2 transport streams
and both standards address RF modulation scheme(s). Where they differ is
the DVB defined RF modulation schemes for terrestrial (DVB-T), cable
(DVB-C) and satellite (DVB-S) while ATSC principally addresses terrestrial
(there is no reason why you could not apply it to cable too). ATSC and DVB
define different modulation schemes, 8-VSB and COFDM respectively, for the
terrestrial transmission.
As far as the transport stream is concerned. DVB defined a set of tables
carrying Service Information which describe the services (DVB uses the term
"services", MPEG uses "progams" for the same thing) in the TS. The
information included data on how to tune to the TS, how services might be
grouped, whether or not services are scrambled, event data, etc. SI is a
form of metadata. While I don't know much about it, PSIP performs the same
basic function for ATSC.
"Anything difference between DVB-S and DBS?"
Well DVB-S defines the modulation for satellite transmission. Direct
Broadcasting Satellite (DBS) is more a generic term. DVB-S is a standard
widely used for DBS services.
"DirectTV and Dish Network are moving to DVB-S2 to take advantage of
H.264?"
Don't know. DVB-S2 is complete revision of the satellite modulation
standard. It opens up the standard for application to other than
transmitting pictures and sound over satellite. The major change is the
adoption of LDPC in place of convocational FEC coding. DVB-S2 is
independent of H.264. DVB-S2 makes more efficient use of the available
bandwidth while H.264 is supposed to reduce the bandwidth required for the
same picture quality. However, there is apparently some date about the
latter, H.264 may not result in the bandwidth reduction suggested by the
hype. Time will tell. Many operators seem to be developing STBs with both
DVB-S2 and H.264.
"Are cable providers using DVB-C or OpenCable, or something else? Will
there be a DVB-C2 (like the -S2)?"
Don't know what US cable operators are using DVB-C or OpenCable. DVB does
lend itself to transmodulation DVB-S to DVB-C fairly easily. AUSTAR does
just that for our Darwin cable network. Don't know if the DVB people are
contemplating a -C2 or not. Probably not much of a need. There is no FEC in
DVB-C that can be improved upon, and two-way is addressed elsewhere.
"What does DVB-T, DVB-H, DVB-C, and DVB-S have in common (other than MPEG-2
T.S. but certainly not modulation schemes)?"
The connection between DVB-T,-C and -S i explained before. DVB-H is an
application which uses the DVB-T transmission to piggy back services to
(H)and-held devices.
Hope this is of use.
Cheers
Terry
Senior Broadcast Engineer
AUSTAR Entertainment Pty Ltd
t. +612 9394 9888
f. +612 9295 0158
e. tsmith@xxxxxxxxxxxxx
w. http://www.austar.com.au/
dan.grimes@xxxxxx
du
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Subject
27/10/2005 09:58 [opendtv] DVB Standard
AM
Please respond to
opendtv@freelists
.org
I really don't know much about the DVB standard, other than it is an open
standard that appears to be more adopted by the U.K. and Europe than North
America.
Is there anything that DVB-T and ATSC have in common (other than purpose
and MPEG-2 transport scheme)?
Is ATSC an open standard like DVB-T?
I know that DVB-T is an open standard and one day I will read through it,
but what are the important points to know about?
Anything difference between DVB-S and DBS? Isn't much of the digital
traffic on satellites in the DVB-S format? And if I'm not mistaken,
DirectTV and Dish Network are moving to DVB-S2 to take advantage of H.264?
Are cable providers using DVB-C or OpenCable, or something else? Will
there be a DVB-C2 (like the -S2)?
What does DVB-T, DVB-H, DVB-C, and DVB-S have in common (other than MPEG-2
T.S. but certainly not modulation schemes)?
How are they being used here in North America, if they are being used?
Dan Grimes
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