NAB Convention Features Emerging Technology

The week-long National Association of Broadcasters Show in Las Vegasclosed on April 23 after showing three new approaches tocontent distribution using the Advanced Television Systems Committee (ATSC) digitaltelevision standard.

Delayed again and again since its inception in the mid1990s, the "this time we really mean it" date for final cut over to the ATSC8VSB DTV system is now set for June of this year. Broadcasters are ready tomove from the introduction phase to the profit enhancement phase, and to helpthem along engineers have come up with three emerging technologies. Unfortunatelythe first is an ode to gadget freaks and the second can't be implemented at allusing present technology, which leaves design engineers with only one that has areasonable chance of making it to the marketplace anytime soon.

Emerging technology number one is 3-D television. A surefirehit with early adopters and video game players, most of the remaining potentialviewers can't get past the need for special glasses to view the content. Couplethat with the need to transmit two images in the same bandwidth normally usedfor one and that means a loss of resolution − something that's unacceptable toviewers accustomed to HDTV.

The technology way out on the event horizon is Ultra HighDefinition Television. Developed by Japan's NHK network, UHDTV featuresperformance at least four times better than Sony's Blu-Ray® 1080p system and it'sstunning to see even in prototype form. The problem is the ATSC system only hasenough bandwidth for 1080i HDTV signals using its MPEG-2 video compression standard.NHK thinks these problems will be solved by 2020 but without changing thecurrent ATSC 8VSB primary compression methodology it's difficult to see howthis will happen. All of this brings usto the remaining emerging technology â€“ one that is ready now, albeit with somechallenges. The third technology is Digital Mobile Television and it's alreadyin the testing phase in several markets.

The standard DTV transport scheme uses MPEG-2 compressionand has Forward Error Correction (FEC) but can't be made to work reliably in amoving vehicle. Multi-path problems and Doppler shift causes signalcancellation and frequently results in reception at a stop light but not whileactually driving. Enter ATSC A/153 (ATSC-M/H), a new encoding subsystem addedto the main ATSC transport scheme.

ATSC-M/H is aimed squarely at the cell phone marketplace andother handheld media. Unlike the basic platform, it uses MPEG-4 compression, arobust FEC and a training sequence to negate signal cancellation problems up to100 mph velocity. ATSC-M/H requires just a 1-2 Mb/sec bit rate to transmit amodified ¼ VGA image of 416x240 pixels plus audio but that still may create aproblem. Regular HDTV signals require most of the available bandwidth andbroadcasters are already using the remainder for things like local weatherradar. How will viewers react if the radar disappears? And will users be ableto understand their cell phone is now receiving signals from both theservice provider and local TV stations? Who do they call when they haveproblems with the DTV? On the technical side, how do engineers and designerscope with TV stations using low VHF channels that require much more than aminiscule cell phone antenna for efficient reception and what aboutintermodulation issues in urban environments?

Still,ATSC-M/H offers a new revenue stream to an industry once thought of as alicense to print money. Broadcasters desperately want the revenue so you'll behearing more about this emerging technology in the near future.

NAB Convention Features Emerging Technology A