P.S. - I will report back next week with measured numbers based on first hand analysis... Mark ----- Original Message ----- From: "Bob Miller" <robmxa@xxxxxxxxx> To: opendtv@xxxxxxxxxxxxx Sent: Friday, August 8, 2008 6:26:01 AM (GMT-0500) America/New_York Subject: [opendtv] Re: From Broadcast Engineering - WRAL tests mobile DTV This is getting more confusing. According to John you need 9 mb/s for two services regardless of whether you are using 1/2 on one and 1/4 on the other? The article says they are using a total of 4.5 mb/s with one service at 1/2 using .6 mb/s and the other service at 1/4 using .3 mb/s. Mark says the efficiencies are 18% for 1/4 and 36% for 1/2. If .3 mb/s is 18% efficient then 100% is 1.67 mb/s and if .6 mb/s is 36% efficient then 100% would be 1.67 mb/s for a total of 3.34 mb/s. 3.34 mb/s is 1.16 mb/s shy of 4.5 mb/s and if John is right and you need 9 mb/s for two services it is 5.66 mb/s shy. If John is right then for .9 mb/s of programming you need 9 mb/s of bandwidth. I don't think I ever thought it would be that bad. If Tom is right as to the article they needed or at least 4.5 mb/s to transmit .9 mbps or a 20% total efficiency. If John is right they would need 9 mb/s for the two services totaling .9 mb/s for an efficiency of 10%, What am I getting wrong? What don't I understand? Was I wildly optimistic last year? Bob Miller On Fri, Aug 8, 2008 at 2:10 AM, John Willkie <johnwillkie@xxxxxxxxxxxxx> wrote: > You cannot draw conclusions until the standard has been released. However, > I believe that public prints have put the o/h at close to 4.5 mb/seconds for > one service, and IIRC, 9 for 2 services. Maybe the term isn't exactly > services, but I can only refer to things which have been mentioned publicly. > > John Willkie > > -----Mensaje original----- > De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En > nombre de Bob Miller > Enviado el: Thursday, August 07, 2008 9:09 AM > Para: opendtv@xxxxxxxxxxxxx > Asunto: [opendtv] Re: From Broadcast Engineering - WRAL tests mobile DTV > > That is what I would like to know. How far was I off last year when in > technical ignorance but from a good source I put out numbers on what > one 8-VSB mobile modulation would cost in bits. What are the numbers? > What is the overhead and what is the % of bits that are real at what > robustness levels? > > Anybody care to compare to DVB-T or H or CDMB-T or is it a big secret > because it is so bad. > > Bob Miller > > On Thu, Aug 7, 2008 at 11:24 AM, <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 >> >> >> >> >> ---------------------------------------------------------------------- >> You can UNSUBSCRIBE from the OpenDTV list in two ways: >> >> - Using the UNSUBSCRIBE command in your user configuration settings at >> FreeLists.org >> >> - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word >> unsubscribe in the subject line. >> >> >> > > > ---------------------------------------------------------------------- > You can UNSUBSCRIBE from the OpenDTV list in two ways: > > - Using the UNSUBSCRIBE command in your user configuration settings at > FreeLists.org > > - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word > unsubscribe in the subject line. > > > > > ---------------------------------------------------------------------- > You can UNSUBSCRIBE from the OpenDTV list in two ways: > > - Using the UNSUBSCRIBE command in your user configuration settings at > FreeLists.org > > - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word > unsubscribe in the subject line. > > ---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways: - Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word unsubscribe in the subject line.