[opendtv] Backward Compatibility of Robust DTV Transmissions

  • From: "Allen Le Roy Limberg" <allimberg@xxxxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Tue, 7 Nov 2006 08:25:31 -0500

Actually, backward compatibility has been given short shrift in proposals
for robust 8VSB.  These proposals time division multiplex robust
transmissions with ordinary 8VSB, but no portion of the robust transmission
is usefully received by legacy receivers.  In short, training wheels
approaches have been ignored.

The time division techniques are not 207-byte segment by segment either,
which makes transmitter design and station operating practice difficult.

Al Limberg
----- Original Message ----- 
From: "John Willkie" <johnwillkie@xxxxxxxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>
Sent: Monday, November 06, 2006 9:12 PM
Subject: [opendtv] Re: Mobile DTV Gets Its Road Test - 11/6/2006 -
Broadcasting & Cable

> The only issue I have with this is: (perhaps a trifle, perhaps not)
> "The idea behind A-VSB is that it is backwards-compatible"
> That is, unless a receiver (or PSIP generator) strictly followed the ATSC
specification provision that says -- in ATSC A/65 -- that PSIP packets will
not have adaptation field headers.   This system appears to require that
there be adaptation field headers in ALL packets, to provide some of the
training signals.
> Other than that paragraph, I don't see any backwards-compatible issues.
And, the funny thing is that I find that I'm much more foregiving about
backwards-compatible issues than other ATSC participants.
> I'm all in favor of A-VSB and other (non-ATSC) changes that are afoot.
They will sell many new PSIP generators.
> I pretty sure I said all of the above without tramping on any
non-disclosure agreements to which I am a party.
> John Willkie
> -----Original Message-----
> >From: Mark Aitken <maitken@xxxxxxxxxx>
> >Sent: Nov 6, 2006 9:02 AM
> >To: OpenDTV <opendtv@xxxxxxxxxxxxx>
> >Subject: [opendtv] Mobile DTV Gets Its Road Test - 11/6/2006 -
Broadcasting & Cable
> >
> >
> >MAA - Well, let us see if folks can begin to imagine more of a future
> >for OTA Broadcasting...
> >**********************************************************************
> >
> >Broadcastingcable.com <http://www.broadcastingcable.com/>
> >w w w . b r o a d c a s t i n g c a b l e . c o m
> ><http://www.broadcastingcable.com/>
> >------------------------------------------------------------------------
> >
> >
> >  Mobile DTV Gets Its Road Test
> >
> >
> >    By Glen Dickson -- Broadcasting & Cable, 11/6/2006
> >
> >If a test on the highways of Buffalo, N.Y., is any indication,
> >broadcasters may be able to use their digital television (DTV) spectrum
> >to reach mobile and portable devices. That's the word from Sinclair
> >Broadcast Group, Samsung Electronics and transmitter manufacturer Rohde
> >& Schwarz, which teamed up to put mobile reception to a tough test.
> >
> >The trio tried out a new transmission technology, called
> >Advanced-Vestigial Side-Band (A-VSB), that they'd like to see added to
> >the Advanced Television Systems Committee (ATSC) digital-TV standard.
> >The informal field tests demonstrated the successful reception of an
> >A-VSB broadcast at highway speed, as Samsung engineers drove a minivan
> >outfitted with special receive-and-display equipment.
> >
> >Broadcasters like Sinclair are eager to master mobile TV, as it
> >represents a way to reach viewers that cable cannot.
> >
> >A-VSB, shown in a simulated laboratory demonstration at the NAB show
> >last April, uses a forward-error-correction (FEC) technique called
> >"turbo-coding" that can dramatically improve reception in difficult
> >signal environments. Turbo-coding trades bits for signal robustness; a
> >turbo-coded stream of 1.5 megabits per second (Mbps) might deliver
> >usable video of only 375 kilobits per second.
> >
> >The idea behind A-VSB is that it is backwards-compatible with the
> >existing 8-VSB transmission system and thus would allow turbo-coded
> >streams of lower-resolution video, suitable for viewing on PDAs or
> >cellphones, to be delivered alongside an HD broadcast within a single TV
> >channel.
> >
> >Sinclair, which raised concerns in the late '90s over the ATSC
> >standard's inability to support mobile or portable reception, is bullish
> >on the technology.
> >
> >The broadcast group was also in a unique position to help A-VSB's cause.
> >Its Buffalo digital station, WUTV-DT, had been operating on a special
> >temporary FCC license as it finalized frequency coordination with
> >Canadian broadcasters. That gave Samsung and Rohde & Schwarz engineers a
> >chance to go to Buffalo in early September and test A-VSB in a
> >real-world environment.
> >
> >"What we did was prove what had been done in the laboratory in terms of
> >simulating an RF channel in a mobile environment," says Mark Aitken,
> >director of advanced technology. "That testing indicated the system
> >should hold together in speeds of up to 150 mph."
> >
> >While Samsung's engineers didn't go that fast, they were able to receive
> >turbo-coded pictures at up to 80 mph. Rohde & Schwarz had modified
> >WUTV's digital transmitter to emit two A-VSB turbo-coded streams, each
> >1.5 Mbps, alongside an 8-VSB high-def signal. Both signals were received
> >in a van outfitted with DTV antennas on the roof and a prototype Samsung
> >A-VSB receiver, about the size of a set-top box, in the backseat.
> >
> >A Samsung YEPP portable digital media player decoded and displayed the
> >MPEG-4 video in the turbo-coded streams, and an ATSC receiver and LCD
> >display demonstrated the limited mobile-reception capabilities of
> >standard 8-VSB broadcasts, compared with A-VSB. The high-def stream had
> >to be played off a server and fed into the transmitter, because existing
> >multiplexers can't combine a normal 8-VSB off-air stream with an A-VSB
> >
> >The tests were, more or less, a fair approximation of real-world
> >conditions. "The results were pretty encouraging," says Mike Simon,
> >manager of advanced technology for Rohde & Schwarz.
> >
> >Formal ATSC testing of A-VSB, being conducted at the Communications
> >Research Centre in Ottawa, began late last month. Field tests will
> >follow, and if all goes well, a draft standard of A-VSB could be
> >circulating within the ATSC by mid 2007. "Whether it's this technology
> >or another, we're very confident we're going to have the capability in
> >the ATSC standard to do mobile and handheld," says ATSC President Mark
> >Richer. "It will just take a bit of time."
> >
> >One thing that hasn't been tested is A-VSB reception on a small portable
> >device itself. C.B. Patel, a consultant on the project, says shrinking
> >the front-end receive technology to that size is feasible for cellphone
> >manufacturers like Samsung but such expensive chip development will
> >probably wait until A-VSB becomes standard. In the meantime, he hopes to
> >organize a broadcast demonstration of the system for the CES or NAB show
> >next year, which will obviously require local broadcasters' cooperation.
> >
> >While it was done as a test for mobile TV this time, receiving A-VSB in
> >a car-based device may have its own merits. Patel notes that General
> >Motors joined ATSC in September: "They didn't become a member just for
> >the heck of it."
> >
> >/E-mail comments to/ glen.dickson@xxxxxxxxxxxxxxxx
> ><mailto:glen.dickson@xxxxxxxxxxxxxxxx>
> >
> >
> > Back <javascript:history.go(-1)> | Print <javascript:window.print()>
> >   2006, Reed Business Information, a division of Reed Elsevier Inc.
> >All Rights Reserved.
> >
> >-- 
> >><>   ><>   ><>   ><>   ><>   ><>   ><>
> >Regards,
> >Mark A. Aitken
> >Director, Advanced Technology
> ><><   <><   <><   <><   <><   <><   <><
> >===================================
> >Sinclair Broadcast Group
> >10706 Beaver Dam Road
> >Hunt Valley, MD 21030
> >===================================
> >
> >"As far as the laws of mathematics
> >refer to reality, they are not certain,
> >and as far as they are certain,
> >they do not refer to reality."
> >
> >------- Albert Einstein-------
> >
> >===================================
> >
> >"I like nonsense---it wakes up the brain cells.
> >Fantasy is a necessary ingredient in living.
> >It's a way of looking at life through the
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> >
> >~ ~ Theodor S. Geisel, a.k.a. "Dr. Seuss" ~ ~
> >
> >===================================
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