Broadcasters hoping to use their digital-television (DTV) spectrum to deliver mobile services will have plenty to see at this week's NAB show in Las Vegas. Two competing mobile-DTV technologies will be on display on the show floor and in demonstration buses driving around the city.
Both systems are the result of partnerships between consumer-electronics companies and transmitter manufacturers, and each promises compatibility with the existing Advanced Television Systems Committee (ATSC) transmission standard and its 8-VSB (vestigial side band) modulation scheme.
“Mobile DTV”—not the same as “mobile TV”—uses the digital-TV spectrum and standard to support mobile video reception. MediaFLO and Modeo, in contrast, use other broadcast spectrum; MobiTV uses cellular networks.
A-VSB (Advanced-VSB), first shown at last year's NAB show, was developed by Samsung Electronics and German transmitter manufacturer Rohde & Schwarz. The new MPH (Mobile-Pedestrian-Handheld) system is being introduced at NAB 2007 by LG Electronics, whose subsidiary Zenith Electronics invented 8-VSB, and broadcast-technology giant Harris Corp.
If one or both mobile-DTV systems were to be standardized and commercially implemented, broadcasters could have a competitive advantage over cable and satellite delivery. Mobile DTV would also help broadcasters keep pace with new mobile services like Qualcomm's MediaFLO, which already uses UHF broadcast spectrum to provide live network programming to Verizon Wireless customers, and Backseat TV, an in-vehicle service being launched this summer by Sirius Satellite Radio.
Unique Link to Stations' Viewers
Additionally, mobile DTV would give stations a unique link with their viewers as broadcast networks increasingly distribute their content on a national basis to new-media platforms. The major networks now make most of their primetime programming available online, either for free or on a pay-per-download basis through Apple's iTunes. CBS and NBC are providing national feeds to MediaFLO that don't include local content; a New York trial by another mobile-TV proponent, Modeo, also featured national, not local, fare.
Del Parks, VP of operations and engineering for Sinclair Broadcast Group, has seen A-VSB and MPH in action and says both prove that “the reception of 8-VSB signals in mobile mode is not only possible but practical.” A longtime proponent of mobile DTV, Sinclair helped run informal field trials of A-VSB in Buffalo, N.Y., last fall and is providing transmission capacity for both NAB demonstrations through its Las Vegas stations, CW affiliate KVCW and MyNetworkTV outlet KVMY.
“I would encourage all broadcasters to look seriously at this,” says Parks. “Although they may not have a business plan in their back pocket today, the possibilities for the future are exciting.”
A-VSB, which was successfully demonstrated during bus rides at the Consumer Electronics Show in January, will be shown using a more efficient encoding scheme that allows multiple mobile-DTV streams to be transmitted alongside a hi-def program.
Single-Frequency Network
The A-VSB camp will also demonstrate reception via a single-frequency network (SFN), which uses multiple transmitter sites to improve reception in tough transmission environments, by placing low-power transmitters and antennas atop the Stratosphere and Paris hotels as well as the Las Vegas Convention Center. Station group Ion Media Networks aided the SFN demo by securing an experimental license from the FCC for Ch. 38 in Las Vegas, which the three transmitters will use to simultaneously broadcast the same A-VSB signal (Ch. 38, currently unoccupied, is to be eventually used for low-power DTV).
“What's being shown here is a small-scale SFN, something that could be used to provide coverage in urban areas,” says Mike Simon, manager of advanced technology for Rohde & Schwarz.
MPH will be publicly demonstrated for the first time, in the Harris booth, in the ATSC “Hot Spot,” and in private bus trips around Las Vegas, delivering multiple mobile streams. Harris and LG will also release results of high-power testing of MPH they conducted in Columbus, Ohio, with Dispatch Broadcast Group station WBNS. The companies measured the reception of MPH by a single 6-inch antenna in a variety of transmission environments and applications, says Zenith VP Wayne Luplow, from walking down the street to driving 70 mph on the highway.
“They were all very excellent results that we achieved,” he says.
Mobile-DTV Standard
Recognizing broadcasters' rising interest in mobile reception, ATSC announced last week that it has formally started the process to create a mobile-DTV standard, ATSC-M/H (Mobile/Handheld). Although the standards process is generally slow-moving, ATSC President Mark Richer says ATSC is “going to be pushed to be very efficient and effective in getting this work done” and could have a candidate standard by the end of the year.
“Most broadcasters I've talked to,” he adds, “feel very strongly that they want to be able to provide digital-TV service directly to mobile and handheld devices using their DTV signal. Many of them think it's extremely important to the future of the broadcasting business, and I happen to personally agree with that.”
Both the A-VSB and MPH camps say there is nothing to stop broadcasters from starting mobile-DTV transmissions now, because such “in-band” transmissions fall within stations' existing 6 megahertz DTV channels and won't impact existing hi-def reception. Harris, for example, is already working on developing an MPH-compliant exciter and encoder to be paired with its DTV transmitters.
“Right now, we're more interested in getting the technology developed and proving it works in the real world, and we'll [figure out] what to do about standardization at a later time,” says Harris Broadcast VP Jay Adrick.
However, standardization is vitally important to enable consumer-electronics manufacturers like Samsung and LG to build devices that can receive mobile-DTV signals. The A-VSB camp has already had lab testing of its system performed at the Communications Research Centre (CRC) in Ottawa and reported results to the ATSC. Field tests with several broadcasters are tentatively scheduled for this summer. Although no formal plan is in place, Samsung VP John Godfrey is hopeful that A-VSB could be considered for standardization by year-end.
“We want to make an open market out of this,” he says. “A-VSB was introduced as an open standard so all manufacturers will be able to build receivers and so all broadcasters will know what technology to transmit with so they can reach those receivers.”
Broadcasters like Parks and Ion President of Engineering David Glenn say they support mobile DTV in general and are agnostic as to which technology gets selected. They hope that a single standard will be selected and suggest that the A-VSB and MPH camps work together to create one robust solution. On that point, it is interesting to note that Samsung and LG already make cellphones that receive the MediaFLO mobile TV standard.
“I think it will be a tough play if there are two standards,” says Glenn, who heads a new Ion division called Omvion that is focused on mobile applications. “Ideally, we'd like to see Samsung and LG be able to work together and come up with one great standard as opposed to two competing ones. That may be a little optimistic, but that would be best for the industry.”
