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

I will have answers next week. I know what was stated from verified analysis, 
but no not what else may have been in the stream, or if (simply) 4.5 Mb/s were 
carved out for convenience . I ask folks to be patient. 

Mark 
----- Original Message ----- 
From: "Tom Barry" < trbarry @ trbarry .com> 
To: opendtv @ freelists .org 
Sent: Thursday, August 7, 2008 10:34:29 PM ( GMT-0500 ) America/ New_York 
Subject: [ 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 @ gmail .com> 
> To: opendtv @ freelists .org 
> 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 @ trbarry .com> 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@ unlv . edu 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 @ trbarry .com>* 
> >> Sent by: opendtv -bounce@ freelists .org 
> >> 
> >> 08/06/2008 08:41 PM 
> >> Please respond to 
> >> opendtv @ freelists .org 
> >> 
> >> 
> >> 
> >> To 
> >> opendtv < opendtv @ freelists .org> 
> >> 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 @ trbarry .com 
> >> 
> >> 
> >> 
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> > 
> > -- 
> > Tom Barry trbarry @ trbarry .com 
> > 
> > 
> > 
> > 
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-- 
Tom Barry trbarry @ trbarry .com 




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