[opendtv] Re: From Broadcast Engineering - WRAL tests mobile DTV
- From: dan.grimes@xxxxxxxx
- To: opendtv@xxxxxxxxxxxxx
- Date: Thu, 7 Aug 2008 08:24:19 -0700
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>
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08/06/2008 08:41 PM
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[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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