[opendtv] Re: From Broadcast Engineering - WRAL tests mobile DTV

Hi Mark -

I'm sure you have much more accurate stated, theoretical, or target numbers than I have access to. But the reported results from WRAL seem to have come in quite a bit shy of those targets, so maybe there was some other overhead there not reported.

It's easy to see that if they got 300 kbps from the 1/4 FEC then they could equivalently instead gotten 600 from that channel using 1/2 FEC, just like the other channel they used. And apparently it would have worked ok since the 1/2 channel didn't have any reported problems in that one report.

But that would then have been a total of 2 600 kbps channels from a total budget of 4500, or only 26.7 percent. Thus the actual test results come in somewhat less than the 36% efficiency you stated for a 1/2 channel using turbo coding.

Maybe the turbo coding budget is also selectable?

- Tom

Mark Aitken wrote:
The numbers I stated earlier are totals for payload...

Mark
----- Original Message -----
From: "Bob Miller" <robmxa@xxxxxxxxx>
To: opendtv@xxxxxxxxxxxxx
Sent: Thursday, August 7, 2008 7:16:52 PM (GMT-0500) America/New_York
Subject: [opendtv] Re: From Broadcast Engineering - WRAL tests mobile DTV

Does the turbo coding overhead penalty remain the same whether you use
1/4 or 1/2?

There is another penalty as well. Will legacy receivers be able to
receive these channels and if they are multicast of the same content
why? If the wind is blowing and cutting out the 8-VSB, as I understand
it, legacy receivers would still not be able to take advantage of the
M/H stream if though they can technically receive it.

And no chance if it is in MPEG4.

Lots of redundant bits and programming.

If using DVB-T, DVB-H or CDMB-T all of the channel can be used for
mobile and fixed. How robust is the variable. In Europe where most
DVB-T broadcast are set up for fixed reception cell phones, lap tops,
vehicles with diversity antennas and portable DTV viewers all with
DVB-T receivers will become ubiquitous for the reception of FOTA and
later subscription and PPV .

In the US I still think it will happen using DVB-T2 and or CDMB-T.

Bob Miller

On Thu, Aug 7, 2008 at 6:15 PM, Tom Barry <trbarry@xxxxxxxxxxx> wrote:
 > The way I understood it the 300 kb stream was 'quarter rate' and the 600
> stream was half rate. The quarter rate then meant using 1/4 FEC or getting
 > only 1/4 of the data bits with the rest of it being redundant bits needed
 > for error correction.  Likewise with the 600 kb stream using 1/2 FEC.
 >
> But it looks like the turbo coding overhead (more FEC) is first subtracted
 > from the 4.5 mbps they allocated, apparently leaving 4*300+2*600 = 2400
 > kbps. So if I understand it and it was stated correctly then the turbo
 > coding cuts the payload bit rate (goodput) about in half again.
 >
> I have no idea if such large FEC overheads would also be needed for DVBx to > get similar quality of mobile/handheld reception. I hadn't thought so but
 > don't have the numbers.
 >
 > Anybody that really knows please feel free to jump in here.
 >
 > - Tom
 >
 > dan.grimes@xxxxxxxx wrote:
 >>
 >> What is the reason for only getting one 600 Kb/s and one 300Kb/s channel
>> out of 4.5 Mb/s? Are the rest of the bits required for overhead or did they
 >> just not fill all the M/H channels possible in the 4.5 Mb/s subchannel
 >> bandwidth?
 >>
 >> Dan
 >>
 >>
 >>
 >> *Tom Barry <trbarry@xxxxxxxxxxx>*
 >> Sent by: opendtv-bounce@xxxxxxxxxxxxx
 >>
 >> 08/06/2008 08:41 PM
 >> Please respond to
 >> opendtv@xxxxxxxxxxxxx
 >>
 >>
 >>
 >> To
 >>        opendtv <opendtv@xxxxxxxxxxxxx>
 >> cc
 >>
 >> Subject
 >>        [opendtv] From Broadcast Engineering - WRAL tests mobile DTV
 >>
 >>
 >>
 >>
 >>
 >>
 >>
 >>
 >> Supposedly from Broadcast Engineering though I copied it from AVS
 >> <http://www.avsforum.com/avs-vb/showthread.php?t=1056025>.  I'm not sure
 >>  I understand it correctly but it looks like they got a total of 900
 >> kbps  (2 channels, 300+600) after error correction overhead from using a
 >> total of 4.5 mbps of the channel bandwidth.
 >>
 >> - Tom
 >>
 >> ---------------------------------------------------
 >>  From Broadcast Engineering - WRAL tests mobile DTV
 >> Broadcast Engineering Mobile TV Update
 >>
 >> WRAL tests mobile DTV
 >>
 >> Users in Raleigh-Durham reported reliable signal reception in most parts
 >> of the station's existing coverage area.
 >>
 >> WRAL-DT, the CBS affiliate in Raleigh-Durham, NC, owned by Capitol
 >> Broadcasting Company (CBC), conducted a series of mobile DTV tests last
 >> week using the Mobile-Pedestrian-Handheld (MPH) system promoted by
 >> Harris Broadcast and others. Hosted by CBC's New Media Group, the tests
 >> featured seven handsets given to station executives living in different
 >> parts of the state. Users reported reliable signal reception in most
 >> parts of the station's existing coverage area.
 >>
 >> To kick off the July 21-25 trial, the station hosted a reception last
 >> Tuesday in which about 50 participants were driven in a bus around the
 >> area with prototype LG Electronics mobile handsets that featured
 >> MPH-compatible reception chips inside. Signal reception of two channels
 >> (half rate at 600kb/s and one-quarter rate at 300kb/s) using about
 >> 4.5Mb/s (including turbo coding) of the station's 19.4Mb/s on-air DTV
 >> stream was reportedly strong everywhere they went during the 10-minute
 >> ride — even at 70 miles per hour.
 >>
 >> The goal of the service, according to John Harris, WRAL's director of
 >> programming, is to extend the reach of the station's television channel,
 >> and make it available everywhere our viewers are. The initial plan is to
 >> simulcast the on-air DTV signal. WRAL-TV broadcasts CBS network and its
 >> own local programming in the 1080i HDTV format as well as in SD digital.
 >>
 >> "We're excited about the possibilities," John Harris, WRAL's director of
 >> programming, told Broadcast Engineering. "The priority is to offer
 >> WRAL's TV signal in another way, in another place. I took one [handset]
 >> east of the station and I just kept driving until the signal dropped
 >> out. I got pretty far before that happened, so I can see the potential
 >> of this service."
 >>
 >> LG Electronics, Zenith Electronics and Harris, all proponents of the MPH
 >> scheme, helped out with the field trials. WRAL-DT uses a Harris Sigma
 >> CVD UHF transmitter, with an MPH module, for the weeklong test.
 >>
 >> In a statement, James F. Goodmon, CEO of CBC, said "mobile DTV
 >> broadcasting enables WRAL to better serve our viewers, communities, and
 >> advertisers by providing a strong combination of anywhere access,
 >> two-way communication, and mobility."
 >>
 >> In 1996, Harris worked with WRAL-DT as one of the first DTV stations in
 >> the country. Two years later, when John Glenn made his historic return
 >> to space, Harris worked with WRAL to conduct the first live HDTV
 >> broadcast of a space shuttle launch to audiences nationwide. Now, the
 >> station is the first to promote mobile DTV service in the state of North
 >> Carolina. WRAL predicts that more than 200 million portable devices will
 >> be sold in 2008, although few if any will have the necessary MPH
 >> reception chips inside.
 >>
 >> WRAL-TV and Capitol Broadcasting Company are part of the Open Mobile
 >> Video Coalition (www.openmobilevideo.com), a nationwide group of
 >> broadcasters driving the deployment of mobile digital broadcast
 >> television. Commercial deployments are forecast for 2009. The group
 >> hopes to have an established standard available to broadcasters by the
 >> February 2009 analog shutoff date.
 >> --
 >> Tom Barry                  trbarry@xxxxxxxxxxx
 >>
 >>
 >>
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 > --
 > Tom Barry                  trbarry@xxxxxxxxxxx
 >
 >
 >
 >
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