That Which Must Not Be Said
Broadcasters all over the world have either ceased or are preparing to cease analog TV transmissions. In the U.S., 105 million mobile phones were sold to dealers in 2005 alone. Is there a connection?
Off-air TV audiences have been shrinking for years. Digital channels offer options for multiple streams of video and audio programming and even datacasting, but, at the moment, neither cable nor satellite is required to carry those additional streams.
Thanks to a government mandate, 2006 sales to U.S. dealers of TV sets with digital off-air reception circuitry first exceeded those without in the week ending March 31. Unfortunately, there is no performance requirement for those digital receivers, and, as they’re not necessary yet, perhaps not even their owners know how well they’ll work.
A form of transmission called enhanced vestigial sideband (E-VSB) “significantly enhances DTV indoor reception in signal-challenged locations when relying on simple antennas,” according to a press release from Zenith issued at April’s NAB convention. Broadcasters have the option to transmit E-VSB instead of the original 8-VSB. Unfortunately, there are virtually no E-VSB receivers; they’re certainly not required by the mandate.
There has been much discussion of repurposing broadcast programming for viewing on mobile phones, but there are a number of problems with the idea. For one thing, few broadcasters own the rights to popular programming. For another, it’s tough to expect a mobile phone user to hold a unit in position in front of their face for an hour. There’s also the problem of seeing anything in a wide shot displayed on a one-inch screen.
A version of the popular TV series 24 sought to deal with some of those problems. Each one-minute episode was filled with close-ups, extra-large bullet holes, extra-loud sound effects and extra blood.
Even if not many mobile phone users are willing to watch ordinary TV programming on their tiny screens, some are. And the huge number of mobile phones suggests that a small percentage paying for video programming can generate significant revenue. Furthermore, mobile phones aren’t the only mobile devices with video-capable displays.
That’s why mobile TV was a hot topic at the NAB convention this year—at least among non-broadcasters. Not only do few broadcasters own popular programming, but in the U.S. at least, they also have no transmission mechanism capable of reaching those mobile devices.
Qualcomm’s MediaFLO uses what used to be a TV channel (55) but not TV transmission. Modeo’s DVB-H uses transmissions at frequencies above the UHF TV band. There have also been discussions of other systems, but none of them are particularly helpful to U.S. broadcasters.
Consider Japan’s One Seg, which was introduced on April 1. Like the other mobile-TV systems, it can transmit television programming directly to mobile phones and other devices. Unlike the others, it uses one segment of the 13 that are transmitted by Japan’s terrestrial television broadcasters using the digital TV broadcasting standard adopted there, ISDB-T.
The U.S.-adopted 8-VSB doesn’t lend itself well to mobile reception. E-VSB helps a little, but it wasn’t designed for mobile reception either. According to sources who were there at the time, mobile reception wasn’t considered an important characteristic for the U.S. system.
So, at the DTV Hot Spot at NAB2006, the word “mobile” did not appear on any large signs. At one exhibit, USDTV was showing how they created a tiny adaptor to allow their older set-top receivers to provide MPEG-4 pay-TV movies; the hard part, according to one of the project engineers, was getting it to work with the existing USB 1.1 ports. At another, HANA (the high-definition audio-video network alliance) was demonstrating IEEE-1394 over home coax. There was a tiny USB adaptor from Jensen for getting digital TV reception on a laptop. There was a scheme for downloading receiver updates.
The most technical-looking exhibit was from Rohde & Schwarz and Samsung. Like the others, it said nothing about mobile. It was for a different form of advanced VSB, this time called A-VSB.
It was only on close examination that certain words stood out, such as “dynamic reception” and “170 miles per hour.” “Mobile” may be a dirty word in ATSC standardization, but it has certainly captured the interest of broadcasters.
Maybe 170 mph isn’t enough for airborne reception. Otherwise, it’ll do.
Mark Schubin is an engineering consultant with a diverse range of clients, from the Metropolitan Opera to Sesame Workshop.
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