Transmitter Makers Target Mobile TV

In the‘80s and ‘90s, as the U.S. solution for high-definition television broadcasting came together in the form of a digital television standard, it became obvious that HDTV itself would not use up all of the bits in a broadcast licensee’s 6 MHz television channel.

In the ‘80s and ‘90s, as the U.S. solution for high-definition television broadcasting came together in the form of a digital television standard, it became obvious that HDTV itself would not use up all of the bits in a broadcast licensee’s 6 MHz television channel.

Business plans aplenty have been proffered for the residual data within those channels, datacasting, additional channels and so forth. One possibility that was not much on the industry’s radar was broadcasting television to mobile devices. But fast-forward to the present, and in-band mobile television, providing mobile video within the DTV channel, is very much on many broadcaster’s minds.

Transmission vendors may be in disagreement about the details of a mobile television standard within the ATSC digital signal, but they are all bullish on the opportunity mobile TV presents to broadcasters.

“[In-band mobile TV] is a real opportunity for broadcasters to put themselves back in the wireless business,” said Jay Adrick, vice resident of broadcast technology for the Harris Broadcast Communications.


Though cellphone giants Verizon and AT&T may have a headstart toward offering mobile video to mobile devices through their cellular networks, Adrick noted that the content being offered is nationally based.

“Opportunity for broadcasters is really built around the fact that they’ve got a lot of local content available,” he said, noting studies showing potential mobile video customers’ interest in local traffic, weather, news and sports information, the stock-in-trade of a local broadcaster.

In shoehorning a mobile TV service into their DTV signal, broadcasters enjoy a second advantage, said Richard Fiore Jr., senior director of North American sales, transmission and mobility for Thomson Grass Valley. “There really is a low cost of entry for [broadcasters]. Their antenna, their transmission line, their transmitters should work for this. They’re just giving up a small part of their spectrum.”

Dave Benco, program manager for broadcast transmitters at Rohde & Schwarz, agreed. “[Broadcasters’] existing infrastructure for the antenna, transmission line and broadcast tower remains absolutely the same.”

Harris (along with LG Electronics), Rohde & Schwarz (teamed with Samsung), and Thomson Grass Valley are the three transmitter vendors vying for adoption of their mobile television broadcasting technology by the Advanced Television Systems Committee (ATSC).

“It’s really very encouraging to see how much energy the industry can put into something when it wants to,” said ATSC President Mark Richer.

Broadcasters are “pushing us to get a standard done in a timely manner,” he said. “They would like to announce a mobility intel service in the beginning of 2009, right around the time of the analog shutdown.”

The point on the spear poking the ATSC is the Open Mobile Video Coalition (OMVC), an alliance of commercial and public TV stations and groups with this stated mission: “To accelerate the development of mobile digital broadcast television, and capture the full potential of the digital television spectrum in the United States.”

OMVC received a boost from broadcasters last month when NAB announced that it was contributing $750,000 to the organization’s efforts.

David Glenn, a member of the OMVC’s technical team and president of engineering for Ion Media, said a number-one priority for broadcaster’s mobile TV is a single standard. “You would want to have a single standard rather than a division of ‘Beta versus VHS’ and let the market decide,” he said. As a personal aside, Glenn said the mobile viewing devices have to offer “a user friendly environment, a good user experience.”

Flexibility is also important. Richard Schwartz, vice president of marketing and product management for Axcera, suggested the European experience with its DVB system might shed some light on the need for flexibility.

“It’s designed so that you can actually make a decision on how much of the robust mobile information you want to broadcast compared to how much of the less-robust, fixed—if you want to call it fixed—standard broadcast bandwidth you want to use.” He suggested stations could vary this mix, some opting for more mobile, some for less.

Fiore said such flexibility could allow an individual station to vary the mobile versus fixed mix within its broadcast day. “I can see, from a broadcaster’s perspective, at different times during the broadcast day, the desire to put more bits out in terms of services to mobility, and less to their television stream, and then switch that, meaning that they’re going to dedicate a lot more to their television steam during primetime, but during rush hour they may want to put more mobility out there.”


Beyond these issues is a debate, boiling below the surface, about whether the standard adopted will involve open or proprietary technology.

Broadcasting to mobile users is very different from broadcasting to fixed TV sets in the home. For one thing, broad adoption of cable and satellite has meant that holes in a broadcaster’s terrestrial signal have been filled in by these services for the home viewer. That’s not so for mobile TV, and the success of the user experience may hinge on the uninterruptability of the signal reaching a moving mobile device.

“[The mobile user] doesn’t want it like a cellphone, where it has dropouts,” said Eddy Vanderkerken, director of sales at Rohde & Schwarz. “He wants a continuous experience.”

One factor much discussed is the difference in propagation between VHF and UHF signals. “VHF doesn’t really work well in [the mobile TV] world,” said Mark Polovick, vice president of sales and marketing at Acrodyne in Phoenixville, Pa. “UHF is definitely a better place to be, there’s no question about it.”

Polovick noted the particular challenge that mobile TV broadcasters face when the mobile device is trying to receive signals inside buildings with thick walls. Citing studies of cellular phones, he said “you lose 20 to 25 dB with the signal going through a wall.”

Harris’ Adrick agreed. While some stations plan to move their digital signal to their legacy VHF channels when full-power analog TV is shut down in 2009, “The reality is, if you are interested in mobile, the best channels are UHF channels. It’s all about propagation and the ability to penetrate walls.”

Benco drew a softer line between VHF and UHF. “I’d say the net difference between VHF and UHF is not a big one. For UHF and VHF versus higher-frequency modes, like L-band and 2 GHz and on up, then there are issues like shadow and building penetration, because those are almost line-of-sight services.”

One factor mentioned by several vendors is that there might be limitations on receiving mobile video from VHF channels because of the challenge mobile device makers will face placing large enough antennas for VHF frequencies in the tiny handsets.


While on the subject of antennas, broadcasters offering mobile TV service may want to rethink their antennas because of the nature of the handheld viewing devices. “I think mobile is similar to radio,” Schwartz said. “It’s something where you have to be more concerned about the orientation of your receive antenna, and I think there’s value in doing circular or elliptical polarization with mobile, because a handheld is not always going to be vertical or horizontal.”

In fact, where a radio listener can rotate a handheld radio to optimize reception, a mobile device viewer is not going to want to look at an upside-down screen, or try to view through the back of the device.

There’s another possibility on the horizon to enhance signal coverage for mobile TV. In the analog transmission world, two signals on the same frequency would interfere with one another. The DTV standard allows use of single-frequency networks (SFNs)—multiple transmitters on the same channel broadcasting the same information.

Deployment of SFNs could ring the cash registers of transmitter and antenna manufacturers, but “There hasn’t been a lot of capital planning [for SFN transmission],” said Polovick. “A lot of these guys are going to get caught, they’re definitely going to be in trouble covering the market.”

Deploying SFNs may also face the challenge of what is technically possible matched against what broadcasters have permission to do. And what’s the FCC’s position on SFNs?

Though demonstrations at NAB2007 and current tests taking place in New York City and Pennsylvania have been allowed through STA and experimental licenses, the commission has not granted a permanent SFN license to a broadcaster.

“Part of that issue is white space,” said Glenn. “Broadcasters believe the white space belongs to us because we can utilize it with SFNs to better serve the public by offering mobile services, and we should be able to do so. Microsoft has another viewpoint on that, though.” Microsoft is not alone on its side of the debate.

While mobile TV can certainly bring a live broadcast to handheld devices, another part of broadcasters’ mobile TV business model may be non-real-time video services.

“Thomson has actually deployed some solutions for DVB-H that could easily be deployed for 8-VSB, where users will subscribe to a service such as a sports update service or weather updates or financial updates,” said Howard Barouxis, senior director for North American sales to broadband and network operators at Thomson.

Subscription business models are certainly possible for mobile TV services, but Adrick pointed to studies that contend the U.S. media consumer may be feeling at the end of his media budget after paying for landline phone, cellular phone, broadband, cable, satellite, games and so forth. He said a good old free, over-the-air, advertiser-supported mobile TV service might come as a welcome relief and be an instant hit with viewers.

However, advertisers will want some proof that the viewers are actually out there, requiring audience measurement tools for mobile TV that have not yet been fully developed.

“The primary method to capture viewing is metering the handset itself, and so we have a metering platform that will actually capture the event and log information from devices, to give an appropriate grid for viewing at the local level,” said Jeff Herrmann, vice president of mobile media at Nielsen Mobile, a mobile services tracking service relaunched by The Nielsen Company last month.

The technology for getting that metered viewing information back to Nielsen is currently in development, but Herrmann spoke of using a backchannel in the device to retrieve it, perhaps via wireless Internet, and possibly via radio technology in the viewer’s home where a resident meter would query the handset when it came in the door.

Also undeveloped at this point are the handheld devices that will receive a broadcaster’s mobile TV service, though the general buzz in the industry is that the Consumer Electronics Show in Las Vegas next month will offer a cornucopia of such handheld and other such mobile TV receivers.