Five-year journey from ATSC mobile TV prototype to adopted standard
Nov 3, 2009 11:53 AM, By Carolyn Schuk
Now enhanced by the new ATSC-M/H standard, North America’s terrestrial DTV standard originally overlooked consumers’ 100 million portable, battery-powered TV sets, says Harris VP of broadcast technology Jay Adrick, who owns four of them.
Mobile TV really isn’t a new idea. Chances are there’s an old Sony Watchman collecting dust in your attic or garage. But when the ATSC began hammering out North American’s DTV standard, they overlooked the Watchman, says Harris VP of broadcast communications Jay Adrick, who played a central role in developing the new ATSC mobile/handheld standard to address the earlier oversight.
“In the NTSC/analog era, there were as many as 100 million portable battery-powered TV sets,” Adrick says. “I didn't even believe that number until I went home and counted — we had four in our house.” But this was overlooked in developing the ATSC DTV standard, he says. “It was all about HD, how many bits you can get down the pipe. The audience was the home.”
But while the ATSC was hammering out the new DTV standard, the entertainment landscape was changing. “The way people live has changed profoundly in the last 15 years,” Adrick says. “PDAs, cell phones, media players, Internet — all of those things happened pretty much as the DTV standard was being finished. Broadcasters suddenly found a lot of their audience was going off to watch television on the Internet. People were beginning to watch video clips on cell phones. Broadcasters suddenly felt they were at a disadvantage, so we began to hear broadcasters talk about the need for mobility about five yeas ago.”
However, the new DTV standard didn’t work for mobile TV, he continues. “It was demonstrated that if you put a receiver in a vehicle moving more than 2mph, the signal would break.* We demonstrated that the first time we showed our mobile system. Every time the bus got above 2mph to 3mph, the [standard ATSC] system stopped working,” he says.
In 2005, Zenith/LG approached Adrick about jointly developing a mobile DTV system. “They had this technology in mind that would be an overlay to the current ATSC standard that would support mobility. We went to Zenith headquarters and looked at a demo; it wasn't much more than a simulation of what could be done for mobility. We began development work and were able to kludge together a transmission system in early 2006.”
The team christened the system MPH, for “mobile pedestrian and handheld,” and demonstrated it at Columbus, OH, TV station WBNS in 2006, subsequently showing the system at the 2007 CES and NAB shows. That year, the OMVC solicited proposals for a mobile system with in-band compatibility with ATSC. After independent determination of viability tests in San Francisco and Las Vegas, the OMVC recommended to the ATSC that MPH be the basis for a standard in 2008.
As the working group for the new standard got down to business, Adrick says that one of the most important early decisions was to base the transport system needed on IP. “By 2009, just before NAB, we had a fairly good idea what the system was going to look like,” he says.
However, the ATSC-M/H working group isn’t just resting on its laurels, Adrick says. “We are already looking at several add-ons. For example, there are people with 700MHz spectrum who have proposed putting mobile TV services on the air, such as DISH Network. They have no requirement for terrestrial ATSC broadcast. Their plan is to launch mobile TV services for pay. So they asked ATSC for a standard to support full-channel [mobile TV] — all of the transport stream would be used for mobile.”
The committee is also working on ATSC-S13, non-real-time applications, to add capabilities for services such as targeted advertising and catch-up TV. Stay tuned, Adrick advises. “Over the next year, we're going to see a number of things that complement the basic standard.”
* Rapidly changing multipath and Doppler frequency shifts are both impairments that caused the system to crash.
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