I believe mobile reception is not the primary interest in Sinclair
Broadcasting pursuing DVB-T2, which uses uses concatenated BCH and LDPC
coding earlier used by DVB for satellite transmissions. If vehicular mobile
reception were of primary interest, the DVB-H standard that is being
abandoned in Europe for lack of commercial interest might be the better
choice. Although the code rate of DVB-H is appreciably lower than DVB-T2, it
appears to be substantially more rugged in regard to the burst noise and
signal drop-out conditions one expects for mobile reception in moving
vehicles.
One reason for looking more closely at COFDM is that its performance in
single-frequency networks can be appreciably better than single-carrier
broadcasting.
IMHO though, DVB-T2 is deeply flawed in its use of rotated QAM symbol
constellation techniques for its plural carriers. The gains noticed in such
practice are those attributable to transmitting the same information twice
with appreciable time-diversity. Rotation of QAM symbol constellations
reduces the size of data-slicing bins during QAM de-maping procedures,
however, which adversely affects performance at low carrier to AWGN ratios.
Single-time retransmission of non-rotated QAM symbol constellations is
preferable, since surprisingly it allows much larger digital payloads in
practice for given performance at low carrier to AWGN ratios. This is
because larger QAM symbol constellations are feasible for a given bin size
for data-slicing, and the two-dimensionality of QAM is exploited.
Hopefully Sinclair Broadcasting engineers will look into this probable
shortcoming of DVB-T2.
Al Limberg
----- Original Message -----
From: "Manfredi, Albert E"<albert.e.manfredi@xxxxxxxxxx>
To:<opendtv@xxxxxxxxxxxxx>
Sent: Tuesday, February 19, 2013 7:55 PM
Subject: [opendtv] Re: Sinclair to test OFDM-DTV2 signal
Gary Blievernicht posted:
http://www.broadcastingcable.com/article/491923-Exclusive_FCC_OKs_Test_of_New_TV_Transmission_Standard.php
-----------------------
excerpt:
WNUV has six months to test from Feb. 15, when the authorization was
granted, though it can seek a renewal. The FCC's Media Bureau, which granted
the experimental temporary authority, makes it clear that only a small
number of test devices can be used and no commercial application is allowed,
both of which WNUV itself offered up as conditions of the experimental
license.
-----------------------
Exciting stuff. And good choice, Sinclair. Maybe we'll finally get some
current comparison results. Although I have a feeling that Aitken and
company are going to be more interested in tuning the service for handheld
receivers, rather than to reach my antenna at ground level, 46.6 miles (74.6
Km) distant! Which now comes in very well indeed, unless we have high winds.
Strong wind is the biggest problem for my reception, even though both
antennas are indoors.
-----------------------
Excerpt:
Sinclair has been arguing that broadcasters should look at hanging on to
their spectrum rather than put it up for auction, suggesting they will need
it for advanced TV services and flexible delivery. It has also said
broadcasters could work with wireless carriers to help offload traffic at
peak periods.
At a Hudson Institute event Tuesday, former FCC chairman Dick Wiley, who
helped develop the HDTV transmission standard, said he thought a new
transmission standard accommodating ultra-HDTV and multiplatform delivery
was in broadcasting's future, but says it might take up to a decade because
it is not backward compatible-it will require new TV sets. Wiley opined that
perhaps if the standard could have been changed sooner, there might not have
been a need for the incentive auctions.
------------------------
Well, you don't need DVB-T2 for the UHDTV part. You need H.265. And
indeed, supporting UHDTV would work against any handheld reception ideas,
because you'd want the system tuned for spectral efficiency. Also, I'm not
sure why Wiley thought "that perhaps if the standard could have been changed
sooner, there might not have been a need for the incentive auctions." The
auctions are specifically to yank away spectrum dedicated to one-way
broadcast, in favor of adding to the two-way cellular service. More than
likely, Mark's comment about offloading wireless carrier traffic during peak
periods was misconstrued. I wouldn't be surprised. What traffic can be
offloaded is only one-way broadcast traffic. DVB-T2 is not a 2-way standard.
Bert
