New digital technologies could put over-the-air TV back in vogue
Like most who grew up in the middle of the 20th century, I have fond memories of my family crowded around a snowy, rabbit-eared tube to watch Bonanza and The Ed Sullivan Show on weekend nights. Back then, broadcast television was king. It was all we had, and we were crazy about it.
By 1960, televisions had found a place in more than three-fourths of homes across the United States. This was just 35 years after Scottish inventor John Logie Baird transmitted the first picture broadcast ever—the moving image of a ventriloquist’s dummy—from his laboratory to a room next door. Throughout the 1970s, ’80s, and ’90s, the average viewer was watching about 3 hours of programming a day, most of it sent on airwaves.
Today, time spent watching TV is at an all-time high. But the 21st century has brought dramatic and permanent changes to the television landscape. And no other entertainment industry has been as deeply affected as broadcasting.
Although broadcast signals still reach almost every American home, fewer than 20 percent depend on them for entertainment. More households now have Internet connections and mobile phones than own HDTV sets. And most of us who do watch television aren’t satisfied with only the scheduled programs we get over the air. So we buy subscriptions to cable or satellite services, stream movies online, play Blu-ray discs, download games on tablets and smartphones, browse videos on YouTube, share them on Facebook, and talk about them on Twitter.
As the modern media cornucopia grows ever more bountiful, some people have inevitably begun to ask: Do we really need—or even want—broadcasting anymore?
It’s an increasingly urgent question. After all, thousands of broadcast stations worldwide collectively own the rights to vast and immensely valuable swaths of radio spectrum. As demand for mobile data skyrockets and interest in broadcast television merely plateaus, telecom companies have been arguing that they can put that spectrum to better use. They have been pressuring government regulators for years to reclaim some broadcast channels and auction off the corresponding spectrum.
The biggest such reallocation happened in the United States in 2009, when the switch to all-digital broadcasting freed up 18 television channels—about one-fourth of the frequencies previously occupied by broadcasters. But mobile operators are still hungry for spectrum, and the broadcast industry is again vulnerable. The United States’ spectrum regulatory agency, the Federal Communications Commission, is now making plans for a new strategy to wrest more spectrum from broadcasters’ hands. Through so-called incentive auctions, TV stations could choose to shut down, move to lower, less desirable frequencies, or share channels in exchange for some of the money the U.S. government makes from selling the rights to the spectrum they give up. If the process succeeds, countries in Europe and other spectrum-challenged regions may follow suit.
Television broadcasting will likely never again be the unrivaled entertainment giant it once was. But the technology isn’t poised for obsolescence, nor should it be. In many ways that we may have forgotten or simply now take for granted, broadcasting offers an attractive—even preferable—service. For one thing, it is the most direct, most reliable way to get information to massive numbers of people at once, whether that information is a hurricane update or the Olympic Games opening ceremony. Broadcast signals also have a broader reach than cable, broadband, or mobile. And best of all, after you’ve bought a television set and an antenna, basic programming is free.
To stay in the game, however, broadcast technology desperately needs an upgrade. Most broadcasters still use the same digital transmission standards first introduced in the 1990s, when watching television was still something people mostly did at a designated place and time. Meanwhile, consumer preferences have evolved: We want our news and entertainment to be versatile and available anytime, anywhere.
Happily, broadcast engineers are now completing a new generation of digital tools that could turn the industry on its head. Imagine watching the World Cup while sharing statistics on your favorite players in real time. Or traveling from Toronto to Mexico City and immediately picking up local news stations for free on your smartphone. To offer such features, broadcasters will have to adopt new standards, and there’s no time like the present. Only new standards can make television cheaper, more dependable, more dazzling, more interactive, and more personalized than it’s ever been.
Broadcast TV could be cool again.
Change has never come easily for television broadcasters. Compared with other big tech-based industries such as computing and cellular telephony, broadcasting has adopted new technologies at a notoriously snail-like pace. This is no fault of its engineers or its executives but rather an effect of the highly regulated environment in which broadcasters must operate.
In most parts of the world, radio spectrum is considered a public resource. Like aquifers and forests, this limited resource is regulated by government agencies to ensure that it is used in people’s best interest. In the early days of radio telecommunications, for example, the U.S. government made a deal with broadcasters: We will let you use some of our spectrum for free, and in return, you must meet certain “public service” obligations.
Among the traditional rules, which also include requirements such as censoring profanity and airing at least one program free of charge to all viewers, broadcasters must adhere to a single technical transmission standard. By making all broadcast stations use the same agreed-upon protocols for sending and receiving signals, regulators can assure anyone who buys a TV that it will work anywhere in the country, receive all channels, and won’t be obsolete anytime soon. The downside, of course, is that consensus takes time. Consequently, when innovations—color pictures, digital video, and now mobile and online services—grab consumers’ attention, the broadcast industry is slow to standardize and adopt them.
For example, the transition from an analog to digital broadcasting standard in the United States took 22 years. The challenge wasn’t just selecting and perfecting a single standard from among the more than 20 possible systems proposed in the late 1980s. That took nine years. The longer delay came about because old analog receivers weren’t compatible with the new digital transmissions. So for more than a decade, until 2009, broadcasters transmitted both analog and digital signals on separate radio-frequency (RF) channels, waiting for “the last granny” to replace her television set or buy a digital-to-analog converter.
The next evolution of broadcasting technology needs to happen much more quickly, and indeed it is already under way. Many standards groups around the world are developing new technologies that build upon today’s basic digital standards. These additions will make digital broadcasting more versatile without totally overhauling it. Old receivers and tuners will continue to read transmissions as they normally would. But broadcasters will also be able to add new features and services aimed at such modern appliances as smartphones and smart TVs.
The Advanced Television Systems Committee (ATSC) in the United States is heading one of the most ambitious initiatives. Following similar actions by groups in Asia and Europe, it released in 2009 an enhanced version of its original Digital Television (DTV) standard that permitted the transmission of broadcast-TV signals to moving receivers. Known as Mobile DTV, or MDTV, the technology is just now starting to take hold in the United States, enabling broadcast stations to deliver programming to some cellphones, laptops, and tablets and to television screens in cars, trains, and buses. But that’s just the beginning of the next tech-driven shake-up of broadcast TV.
Beyond MDTV, the ATSC is developing further enhancements to DTV, collectively called ATSC 2.0. The new standards will bring to broadcasting all the features modern media consumers have come to expect from their TVs, tablets, and pocketable media players—and maybe even some features they don’t yet know they want.
Among other perks, ATSC 2.0 will enable newer receivers to store programs, clips, and movies locally for playback on demand. It will also let viewers subscribe to additional free or paid broadcast channels and personalize the look of their displays as well as the programs and advertising they receive. And there’s at least one potential game changer: ATSC 2.0 will take advantage of Internet-connected TVs by enabling broadcasters to integrate online content, such as voting platforms or social networking services, into shows delivered over the air. For instance, viewers could pick, in real time, the winners of contestant game shows, such as “Dancing With the Stars.” Or, while watching a broadcast news program, they could read relevant hyperlocal updates on their TV screens, tablets, or phones.
To understand how ATSC 2.0 will make these features possible, you need to first understand the existing DTV standard.
When the ATSC completed the standard in 1995, most mobile phones still had tiny text-only screens and long antennas, and they weighed about as much as a full soft-drink can. The idea of watching television on such a gadget seemed as likely as surfing the Web on a personal computer that fit in your pocket. So the ATSC focused on maximizing benefits for large, stationary screens, which typically experience far less signal distortion and variability than a moving receiver. DTV therefore prioritizes high definition quality over robust signal-repairing schemes.
A DTV signal has a bandwidth of 6 megahertz and is capable of delivering slightly more than 19 megabits per second. Raw high definition video streams at about one gigabit per second, which means that before a high definition program is broadcast, its data must be compressed at a ratio of at least 50 to 1.
After compression, more algorithms at the broadcaster’s transmission facility bundle video, audio, and ancillary data (such as closed captioning and program ratings) into packets. Processing equipment at the transmitter then multiplexes the separate packets into a single stream, randomizes them, interleaves them by time, and applies error-correcting codes.
Adding error-correcting bits to the data stream helps assure good television reception. Broadcast signals are disturbed in all sorts of ways: Rain and foliage weaken them, atmospheric conditions distort them, and buildings reflect them, producing multiple delayed copies of the original signal. The resulting damage and interference make it difficult for a receiver to reconstruct the original data stream, causing a disrupted or frozen picture. Error correction increases the chances of recovering the corrupted data.
However, in order to deliver a good picture consistently, even to a stationary receiver, error correction alone isn’t sufficient. After the packet stream is error-corrected but before it’s broadcast, training sequences are added at distinct intervals. A training sequence is a short segment of pseudorandom data that a receiver already knows. By comparing this known sequence with the received signal, the receiver can estimate changing RF channel conditions and tune its algorithms to best correct for signal impairments, such as multipath, scattering, and power decay.
At this point, the broadcast is nearly ready for transmission. Finally, the digital bit stream is encoded in the RF waveform that will carry the broadcast through the air. The ATSC’s DTV system accomplishes the encoding through a modulation scheme known as 8-level vestigial sideband, or 8-VSB. This method maps the binary data onto the waveform by varying its amplitude among eight different levels.
It’s worth noting that 8-VSB works very differently from modulation methods employed by other dominant digital television standards, including China’s Digital Terrestrial Multimedia Broadcast (DTMB) standard, Japan’s Integrated Services Digital Broadcast (ISDB) standard, and the Digital Video Broadcasting (DVB) standard, which was pioneered in Europe. These standards use variations of a modulating technique called orthogonal frequency-division multiplexing (OFDM), which divvies up the bit stream among several thousand carrier waves at different, closely spaced frequencies, each supporting a low data rate. The multiple small-bandwidth carriers are more resistant to signal deterioration—a characteristic that makes OFDM well-suited to mobile television.
But 8-VSB, which uses a single wideband carrier, has the advantage of being able to carry more data. Remember, the ATSC optimized this system to deliver high data rates to fixed receivers. Now, advanced standards such as MDTV and ATSC 2.0 will add to that capacity many more desirable capabilities.
Perhaps the biggest technical challenge to enhancing a digital standard is working within a limited amount of spectrum. The enhanced features—mobile reception, on-demand shows, the integration of online content—require that broadcasters send more data than in a standard DTV-only transmission. Without the possibility of acquiring more spectrum, stations must send the augmented signals in-band—that is, within the RF channel they already use.
Part of the solution is better data-compression algorithms, which reduce the number of bits needed to send the main program. Broadcasters can then use the freed bit capacity to stow additional information in a broadcast signal. Newer receivers will be able to detect and exploit the supplementary data, while older ones will simply ignore those streams they don’t understand.
With mobile broadcast TV, the main challenge is overcoming poor reception conditions. In addition to typical disturbances, a signal traveling to a moving receiver is subject to Doppler shift and a constantly changing radio environment, which worsen degradation. The ATSC’s MDTV standard solves this problem by using more robust error-correcting codes. It also calls for additional, more closely spaced training sequences—those known data segments that help a receiver adapt to changing RF channel conditions. The extra, longer sequences fine-tune the signal repair process, ensuring a clear picture.
The keystone feature of ATSC 2.0 is its ability to support broadcaster-initiated interactivity between real-time programming and data saved locally at the receiver or retrieved online. The combined broadcast-broadband experience is the broadcasters’ ticket to staying competitive in today’s connected world. It can be as simple as a one-click product purchase or as stunning as a virtual tour of the winning race car in the Indianapolis 500.
According to the ATSC 2.0 protocol, broadcasters would create these elements by sticking many small bit sequences, called triggers, in the broadcast data stream. A trigger can do several things. For instance, it can announce the availability of interactive content, tell where that content is located locally or online, and signal when it should appear. A trigger can also mobilize more complex application-like objects, which are delivered in a broadcast stream or downloaded from the Internet. These scripted objects act like very simple computer programs in that they control the timing, display, and fetching of various data to produce a personalized, interactive scene.
Advanced digital standards like ATSC 2.0 may be just the key to revitalizing the broadcast industry within the next decade. But technology, like the modern television viewer, never sits still for long. To provide really transformative services in the future, broadcasters will need to completely overhaul digital systems. As receivers get smarter, display sizes grow and shrink, and techniques for packaging, labeling, and modulating data advance, existing digital standards won’t be able to sufficiently support them. In anticipation, the ATSC and other standards organizations have already begun work on third-generation standards, which, unlike MDTV and ATSC 2.0, won’t be compatible with today’s receivers.
Big challenges lie ahead, not just for engineers but also for lawyers, lobbyists, regulators, and policymakers. At the moment, the pitch for a radical change in broadcast standards raises questions we can’t yet answer. Perhaps most formidable is how broadcasters will plan the transition from an old standard to a new one without frustrating customers still using legacy systems. Simultaneous broadcasts using both old and new technologies may not be feasible, because broadcasters in the future will likely have even less wiggle room on the radio spectrum than they do today.
Despite the hurdles, work toward a totally fresh, ultramodern standard invites an alluring possibility. Broadcasters have long dreamed of a single digital standard that works on any television or mobile tablet anywhere in the world. Besides pleasing the world travelers who watch TV on their mobile gadgets, a universal standard could drastically improve economies of scale and drive down the prices of television sets and receivers even lower than they are today.
In the end, an agreement of such international scope may prove too ambitious, and the dream may never become reality. But many broadcast players around the globe are now seriously considering it.
This past April, 13 television organizations—from Europe, Brazil, Canada, the United States, China, Japan, and South Korea—formed the Future of Broadcast Television (FOBTV) initiative to collaborate on the next next generation of broadcast systems worldwide. Already, FOBTV has attracted more than 40 additional members, including production equipment suppliers and consumer electronics manufacturers.
The diverse group may not yet have a technical solution. But when its founders signed the inaugural memorandum of understanding, they at least agreed on one thing: “This is a defining moment for the terrestrial television broadcast industry.”
This article originally appeared in print as "The Broadcast Empire Strikes Back."
About the Author
Lynn Claudy has made a career out of entering industries during major technological shifts. He began engineering phonograph cartridges around the time compact discs emerged. When he joined the National Association of Broadcasters, television stations were preparing to go digital. Now NAB’s senior vice president for technology, he says, “I’m just waiting for the next transition.”