08.06.2006 08:00 AM
OTA forever!

Many have heralded the death of terrestrial, over-the-air broadcasting. Although the number of viewers has been dropping, it is still here. From another perspective, with cable and DBS carriage, local OTA channels are available over every distribution channel.

By July 2007, all DTVs with screens larger that 13in must contain an ATSC tuner making it easier to receive OTA anywhere — in the backyard, in a car, at the beach or in a stadium. For those who carry a cell phone or PDA, efforts are underway to deliver broadcast TV to these and other handheld devices.

The multicast enigma
Many broadcasters have yet to figure out what to do with their 6MHz of DTV spectrum when broadcasting only one SD channel. An initial attempt in 2000 was the iBlast venture. Excess OT channel spectrum was going to be used for delivery of subscription data services. Many broadcast groups, such as Tribune, Meredith and Cox, got on board. To far ahead of technology and consumer needs, the remnants of the vision can be explored at the iBlast Web site.

In a recent attempt at maximizing OTA use, USDTV offered popular cable services, such as ESPN and Discovery, over the air to consumers. The first systems were deployed in Salt Lake City, Albuquerque, Dallas/Fort Worth and Las Vegas. Consumers purchased a USDTV decoder and paid a flat rate of $19.95. USDTV planned a network-wide conversion to MPEG-4 AVC compression. The vision ended in July with bankruptcy proceedings.

To date, no organization has discovered a viable business model for leasing unused, multicast spectrum from OTA broadcasters. Several companies are trying a different approach, using a full 6MHz channel to deliver DTV services to handheld devices.

The channel 55 approach
A venture by Qualcomm, MediaFLO is facilitated by the purchase of UHF channel 55 across the US for delivery of TV content to cell phones and other handheld devices. A proprietary media distribution system (MDS) has been designed to deliver high-quality video to handsets as a background transfer in an opportunistic manner. The technique is called clipcasting.

Video is delivered using MPEG-4 in QICF display resolution and occupies about 1MB of storage for each minute. Audio is AAC coded. The DRM implementation separates content from licensing and includes program expiration enforcement. Currently, 3G CDMA cellular packet networks are supported.

The Media Program Guide (MPG) presents what programming is available and when it can be watched. Hence, the MPG is both a status-reporting and content navigation interface. The viewing and delivery experiences are separated. There are no download progress bars.

The 700MHz approach
Aloha Partners is based in Providence, RI, and was the largest buyer of spectrum in the FCC auctions of 700MHz radio frequencies in 2001 and 2003. Aloha currently owns 12MHz of spectrum covering 60 percent of the United States, including all of the top 10 markets and 84 percent of the population in the top 40 markets.

Hiwire, a subsidiary company, will test its mobile TV offering in Las Vegas using UHF channels 54 and 59. DVB-H. H.264/MPEG-4 encoded content will be delivered to wireless devices at up to 30fps.

Mobile TV content will be aggregated, processed and prepared in MPEG-4 format and originate from SES AMERICOM's IP-PRIME IPTV Broadcast Center in Vernon Valley, NJ. The reformatted DVB-H content will then be delivered over the SES AMERICOM satellite-based distribution network to Hiwire's broadcast distribution towers.

But there’s a fly in the ointment. At this time, only about one in four of Aloha's licenses can be used for broadband because UHF broadcasters are currently transmitting on these frequencies.

The Windows Mobile approach
Modeo is the third entrant attempting to capitalize on delivery of digital television broadcast live to mobile phones. A Microsoft Windows Mobile 5.0 DVB-H Smartphone, manufactured by HTC, can receive Modeo's DVB-H mobile broadcasts. Windows Media Video, Digital Rights Management and Media Player 10 Mobile are used to playback video and music stored in multiple formats. Windows Media Audio (WMA), MP3 and AAC will be supported.

The Windows Mobile 5.0 platform also enables use of mobile versions of Microsoft Office programs such as Internet Explorer Mobile and Outlook Mobile. Users will be able to surf the Internet and synchronize calendars, contacts and email messages with an office or home computer, in real-time.

Modeo is also integrating mobile media into laptops, PDAs, personal AV players and handheld game systems.

Power levels on “10”
Returning to the OTA core distribution channel, a big question mark is uncertainty about what is going to happen after the analog shutdown and all DTV stations go to full power. Will the current 8-VSB demodulators be able to handle the increased signal power levels and the resultant increase in interference?

The ATSC and demodulator IC manufacturers have not been idle in addressing criticism of 8-VSB DTV transmission. At least partially due to the COFDM vs. 8-VSB battle in the early rollout of DTV, intense efforts have been underway for years to improve mutltipath rejection and improve receiver performance.

Sarnoff, a Grand Alliance member, continues to contribute to the DTV cause. Addressing the interference problems with mutipath echos, the ClearLoc demodulator takes a step forward to solve reception problems. The chip can also demodulate QAM signals and is compliant with ATSC Digital Television Standard (A/53) and ATSC Recommended Practice: Receiver Performance Guidelines (A/74) as well as digital cable ready (DCR), adhering to OpenCable ITU-T J.83 Annex B.

Not to be left behind, Zoran is leveraging its years of expertise in RF technology and has developed the Cascade2, a DTV demodulator IC. The chip is also both ATSC and OpenCable compliant.

What about 1080 60P?
Eventually 1080 60p will become practical to implement in production infrastructures. 1080 60p capable receivers are already available. At this moment, it is impossible to squeeze this highest resolution HD signal into 6MHz. Will this tip the hand in favor of cable or satellite delivery? 1080 60p is a natural fit for advanced codecs. Bit rates would have to be half of what they are now to make OTA 1080 60p feasible. Maybe the FCC shouldn’t be in such a hurry to have terrestrial broadcasters return their second channel…

Something to consider
Much to do has been made of late heralding the cutting edge brilliance of video to cell phones and other personal media consumption devices. Sure, if I were standing in a line, it would be nice to watch something to pass the time. Or if I’m on a train, I’d love to catch my favorite team live. But given a choice, I’d like my TV broadcast quality on a 13in or bigger HD screen.

Here’s a call to CE receiver manufacturers: Why not develop a 13in LCD mobile DTV receiver? Think about it, I’m in the backyard next Memorial Day and Cousin Jack, the family technophile is boasting about his amazing 3.5in screen and how he can watch his favorite show a few days after it has aired. You smile and walk him over to the barbecue pit where you’ve been flipping burgers, and his mouth drops open wide as he sees your beautiful 13in HDTV and the live broadcast of the Indy 500. Once again the broadcast industry will be back where it began. Good old over-the-air transmission will go where no one else is able to go, everywhere.



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