Brian's Brain

Continued from 'NAB 2008: Mobile Television Matures'...

Another NAB meant another public exhibition of Samsung, Rohde&Schwarz and (a new partner this year) Nokia's A-VSB technology. See my March article for the details of last year's bus-based demonstration. The specifics this time around were different, and were also reflective of the maturation of this particular ATSC-M/H candidate.

First and foremost, this year's bus didn't tote a diversity antenna array. Although the Rohde&Schwarz representative who acted as demo spokesperson said that diversity arrays continued to be a valid means of boosting reception quality, the point here was to point out that a lower-cost single-antenna setup also delivered perfectly adequate results. Also, this time around all of the A-VSB broadcasts were 1/4 rate Turbo streams, at QVGA resolutions and with 30 fps frame rates.

The A-VSB demonstrations tuned in two digital RF channels, 22 and 40, both broadcasting from antennas ~25 miles away on Black Mountain. The former, which you can see in the bottom left corner of the LCD mounted on the back wall of the bus, came from Sinclair and combined three feeds:

• A national live broadcast (<2 Mbps)
• A local live broadcast of KVMY (<2 Mbps), and
• pre-encoded interactive content (~2 Mbps)

controlled by a user-accessible program guide located along the right-edge border of the respective video feed. Also included was a SRS (supplemental reference sequence) stream of 1.44 Mbps, for a total bandwidth utilization of ~7 Mbps.

The top two mobile digital video presentations (local to the left, and national to the right), as well as the conventional ATSC-based one in the bottom right corner of the LCD, come from Telemundo affiliate KBLR. The two A-VSB signals each consume ~2 Mbps of bandwidth; after also subtracting out SRS usage, the remainder of the 19.2 Mbps stream is available for the legacy ATSC broadcast. As you can see from the images (captured using my new cost-effective digicam), the ATSC-delivered video dropped out whenever the bus was in motion.

Samsung showcased A-VSB reception on a diversity of hardware platforms, including a laptop computer:

UMPCs:

And cell phones and MP3 players:

The company proudly proclaimed that all of the demo platforms incorporated third-generation A-VSB receiver silicon. While a Samsung spokesperson admitted (while simultaneously deferring my request for spec specifics) that power consumption wasn't yet where the company wanted it to be, at this point the silicon design achieves full functionality, and now Samsung can focus on optimizing both the circuitry (via clock-gating and other techniques) and the process it's based on in order to extend resultant system battery life.

Granted, I'm not privy to the so-far results of the Open Mobile Video Coalition's testing, nor do I have insight into whatever ATSC back room politicking the backers of A-VSB (and its competitors) may be doing. As Blu-ray's recent victory showcased, technical superiority doesn't necessarily ensure standards (or, more importantly, market) success. However, don't discount the three consecutive years' worth of public NAB demonstrations put on by the A-VSB coalition (technically speaking, the technology was first shown behind closed doors at the January 2006 Consumer Electronics Show), or the robustness of the A-VSB ecosystem as demonstrated last week (particularly in light of ATSC spokespersons' repeated aspirations to have a standard up and running in less than 10 months' time!). Samsung and its partners have clearly made significant investments and are determined to achieve a profitable return on them. Although A-VSB won't necessarily capture the entire ATSC-M/H prize, I wouldn't be remotely surprised to see the majority of patent royalties being garnered by A-VSB backers in years to come.

Continue reading with 'NAB 2008: Alternative Mobile TV Services'...