Mobile DTV demo this spring
Only broadcasters can deliver this kind of TV
Published Jan. 25, 2010
By Steve Behrenshttp://www.current.org/dtv/dtv1002mobile.shtml
Another DTV transition is coming soon, and advocates think it will be a hit with Americans. If broadcasters are lucky, it'll also be a hit with the FCC.
With the commission's Broadband Plan brigade making noises about the rationality and economic payoff of moving TV to wired delivery systems and satellite--freeing up more spectrum for consumers' mobile devices--here's a kind of TV that only broadcasting can transmit: TV received in a moving car.
"You cannot overstate the importance of mobile to broadcasting," said Mark Richer, president of the Advanced Television Systems Committee, at the NETA Conference this month in Las Vegas. Richer's committee put together the DTV standard in 2006 and last October wrapped up the Mobile DTV standard. "The ramifications of going to Mobile are far greater than for the switch to digital."
Washington policymakers will get an eyeful in March or April when the Open Mobile Video Coalition stages a "consumer showcase" on eight stations, including two pubTV channels --Howard University's WHUT and MHz Networks' WNVT in suburban Virginia.
The coalition includes more than 20 commercial TV station groups, including Fox, NBC, Univision, Ion and Sinclair, plus PBS, CPB and APTS.
PBS Chief Engineer Jim Kutzner, active in the Open Mobile Video Coalition promoting the technology, noted at NETA that it's the first time in his career that a new TV standard will move to lower specs. The image is composed of just 416 pixels by 240 lines. But you don't need high-def for the kids in the back seat of a Dodge Caravan.
Participants in the Mobile DTV test in D.C. will try watching on an array of new receiving devices--many of which debuted this month at the Consumer Electronics Show--such as Dell Inspiron Mini 10 netbook computers, Samsung Moment phones, LG mobile TV sets and Valups' Tivit portable receivers that feed portable monitors via Wi-Fi.
Stations will use Harris and Rohde & Schwarz equipment to add the signal to their DTV transmissions.
The showcase isn't a test of the technology, Richer said, but a test of what consumers think of it.
What will viewers get? Public TV leaders at NETA predicted Mobile DTV will be used for simulcasts of live TV as well as weather alerts, datacasts of traffic maps and sports scores, radio with pictures and interactive brainstorms yet to come, CPB is backing a PBS experiment with a 24-hour children's TV service.
Though commercial broadcasters are mum about their business plans, said CPB Senior Vice President Mark Erstling, they agree that kidvid is Mobile DTV's "killer app."
There's even hope that Mobile DTV will seduce 18-to-24-year-old "millenials" to watch news and public affairs TV, said Lonna Thompson, general counsel of the Association of Public Television Stations, speaking at the NETA Conference. A survey indicated their level of interest would double, she said, because they'd no longer be "tethered" to a set in the living room.
Mobile DTV may be able to do a tolerable imitation of cable: Planners say broadcasters in D.C. will air at least 20 different Mobile channels during the tryout this spring.
It can also do a limited imitation of video-on-demand by "clipcasting"--constantly downloading, in advance, an array of popular videos to be stored in users' receivers--though it won't let users choose among every video on the Web.
Where it may shine is fulfilling past visions of interactive TV that cable has failed to realize. If the mobile receiver is a cell phone, it can provide a return path for ordering pizzas, voting on American Idol or whatever users want to click
"There will be great businesses built in Mobile DTV," predicted Andy Russell, senior v.p, PBS Ventures, at the NETA Conference. "We think the possibilities are enormous with this new platform." Researchers predict Mobile will generate $1 billion a year in ad sales, with interactivity sweetening the profitability. He anticipates commercial broadcasters' ad sales will rise further when they work out ways to hyperlocalize service, promoting services geographically close to viewers.
There are even revenue enticements for public TV. The FCC regards datacasting as an "ancillary and supplementary" nonbroadcast service, for which public TV stations can earn revenues, said Thompson. The commission would require that the station pay it a 5 percent fee on any such revenues, she said. The station also must maintain a broadcast signal using 4.7 mbps of its bitstream, Kutzner said.
One possibility is that cell carriers will lease capacity on broadcast signals to haul video. Compared to the way some phone companies transmit video, one circuit per viewer, it's an economic winner, said Kutzner. Some cell companies spend $4 an hour per video user for transmission while Mobile DTV in a large market, reaching many viewers at once, would spend 1 cent per viewer\\
Mobile DTV has been under discussion for a decade and OMVC was formed in 2007 and ATSC's standard-setting work began in June 2008. Mobile wasn't dreamt up to help broadcasters keep spectrum, but "it's fortunate we were so far down the road," Kutzner told Current. "It's a very good illustration" of broadcasting's capabilities.
"When [Mobile receivers are] in the consumers' hands, the government won't have the nerve to take them away," said Erstling.
No FCC action is required to approve Mobile DTV, advocates said, because it fits within the DTV standard defined by the Advanced Television Systems Committee.
While wired broadband may be the rational choice to deliver TV to the multitudes in their homes, broadcasting is a rational option for delivering it to receivers on the go.
"It is a great way to provide content that is widely used. It is inherently efficient," Richer said at NETA. "We need to . . . leverage those benefits inherent in broadcasting."
No go for low VHF channels
Mobile isn't an option for stations on the lower VHF channels, Kutzner said at NETA. The physics of broadcasting make it impractical because the antennas to receive Mobile on Channels 2 through 6 would be "so large that they wouldn't make any sense." Higher VHF channels through 13 would be less handicapped. But UHF stations generally can provide excellent coverage within 15 miles and good coverage within 40 miles, he said.
The technology has off-the-shelf aspects. It uses the Internet protocol for transmission, mpeg video and iPod audio. To make the Mobile signal receivable in a speeding vehicle, however, the signal must carry a ton of data for forward error correction. The extra data helps the receiver instantly reconstruct content if it doesn't catch all the bits accurately.
Ordinary DTV for fixed receivers already reserves a third of its bitrate for error correction (the whole broadcast DTV channel accommodates 27 mbps, Kutzner said, not the 19.4 mbps we usually hear about).
For Mobile DTV, the transmitter uses, in addition, 66 percent to 84 percent of the Mobile signal's capacity, for error correction, Kutzner told Current.
For broadcasters, Mobile DTV is an add-on to DTV transmissions.
A broadcaster's big commitment is a portion of the TV channel. Of the total 19.4 megabits per second payload in a standard broadcast channel, a Mobile channel would take about 3 mbps, Kutzner said.
Then there's the cost of accessorizing the transmitter--$75,000 to $200,000, Erstling said at NETA.
It's cheaper for stations with newer transmitters; they may need only a software upgrade. Older transmitters would need a new exciter, mobile multiplexer and a post-processor that cost, altogether, $75,000 to $150,000 for one standard-def channel and $10,000 to $20,000 per each additional channel, Kutzner told Current.
For broadcasters interested in learning more, ATSC will hold a day-long seminar on Mobile DTV Feb. 3, 9 a.m. to 4:30 p.m. in Washington, D.C. The committee's website is taking seat reservations at atsc.org/seminars/mobile10.php