The cable industry's move into digital TV has suddenly become much more complicated than the first phase of that process was expected to be, thanks in large measure to how long it has taken to get started.

Through the four-plus years since Tele-Communications Inc. CEO John Malone spelled out plans for the 500-channel digital TV system, operators waited for the boxes to arrive at price points they could work with, anticipating that first-generation digital represented a means of offering the customer more choices without eating up a lot of bandwidth.

Enhancements like high definition TV, on-demand video and fully interactive services were viewed as components of a fairly distant and largely indecipherable future that would be addressed once the initial digital platform was in place.

But a growing number of MSOs are recognizing the initial platform is going to be what was once considered second-generation, encompassing support for interactive video and HDTV, as well as broadcast standard definition digital TV. The shift in thinking is fueled by developments on separate fronts, where the success of Internet protocol and high-speed data technologies is opening opportunities for two-way multimedia just as the government and broadcasters have gotten serious about HDTV.


"I think the industry, at the highest level especially, regards high definition as a top priority," says Richard Green, president of Cable Television Laboratories Inc. But, he acknowledges, the shift in focus is so new that engineers couldn't be blamed for declaring HDTV to be on a back burner, as some apparently did in recent discussions with a New York Times reporter about cable's digital TV agenda.

The article, which appeared May 5, asserted that "none of the major cable operators are making plans to provide high-definition programming." "The Times got it all wrong," Green says.

In fact, top-level attention is especially strong on the HDTV side at this point, given the industry's need to open a dialogue with broadcasters before it can formulate its own strategic approach to high definition. Cable CEOs, working through the executive committee of Cable Television Laboratories' board, have convened an ad hoc group under the leadership of Cox Communications CEO James Robbins to open a dialogue with broadcasters which they hope will help both industries to work cooperatively on bringing high definition and standard definition digital broadcast signals to cable customers.

"There are a lot of things we bring to the table that could benefit broadcasters as long as there's flexibility to do things in ways that aren't damaging to our interests," Green says. The crucial issue is how must-carry rules are applied in the digital domain, which is a major point of dispute between the National Association of Broadcasters and the National Cable Television Association as they lobby the FCC for an interpretation favorable to their interests.

Cable operators may want to transmit broadcasters' HDTV signals, Green notes, but they don't want to be forced, as they would be under a rigid interpretation of must-carry, to provide only one HDTV channel per 6 MHz channel if the digital modulation system they are operating can support two. Moreover, cable operators want some flexibility in instances where broadcasters choose to multiplex several digital channels into the 6 MHz over-the-air feed rather than using the spectrum for a single HDTV channel. "If one of the broadcaster's digital channels is a CNN feed, you don't want to have to consume capacity for that when you're already delivering CNN," Green says.

Cable leaders hope to reach a compromise on a business framework that recognizes the mutual benefits of cooperation rather than engaging in a protracted battle that could end up in the courts. "What we have is a digital box that can translate broadcasters' (standard definition) signals for viewing over conventional TV sets, which gives them a market base they wouldn't otherwise have if they waited for consumers to go out and buy digital TV receivers," says a senior cable executive, asking not to be named. "One of the things we'd like to explore is the possibility of them sending us their signals over a separate feed using our modulation scheme, which would allow a direct pass-through to the set-top without incurring the costs of modulation conversion."

At some point, cable also hopes to get a better idea of the actual HD format broadcasters will use, though, at this point, most cable engineers assume their broadcast brethren will stay with the entrenched and bandwidth-efficient interlace approach rather than going to the progressive scan favored by the computer industry. So far, CBS is the only network to announce its choice, which is the "1080-I" interlace option.

Fortunately for cable, it can win an advantage no matter who chooses which format by being flexible enough to accommodate both, notes a senior industry executive, asking not to be named. "If we play our cards right, we'll be the one outlet through which consumers can get access to programming in both formats," he says. "To the extent we support both sides in this religious war, we'll help persuade manufacturers to offer receivers that are dual-purpose, and that will be a win for everyone."

By fall of next year, HDTV receivers will be on the market and, if broadcasters live up to their commitments, the big four network owned-and-operated affiliates will be putting out HD programming over the newly-allocated digital broadcast spectrum. That doesn't give engineers much time to sort through their options, notes Bob Zitter, senior vice president of technology operations at HBO, which has committed to providing an HDTV feed of at least some of its programming in tandem with the earliest broadcast startups.

Much remains to be worked out in the company's plans for the HDTV feed, Zitter says, including a choice of formats and a decision on whether to include programming created in NTSC along with the high-resolution, widescreen film and video material that accounts for about 70 percent of the network's content. "My staff and I are going to be quite busy dealing with these issues over the next year," he notes.

HBO and Madison Square Garden Network are the only cable programmers to make known their HDTV plans, but industry CEOs clearly expect more suppliers to step up to the challenge of providing an early package of product that would give cable a strong position in HDTV. "Comcast (Corp.) is prepared to make the technological commitment" to HDTV, says Comcast President Brian Roberts, but he adds, "Of course, we would welcome more programmers to help fill the digital pipeline we're building."

Cablevision Systems Corp. subsidiary MSG plans to begin an HDTV feed in 1999, with occasional HDTV broadcasts of major events slated to get underway in an earlier, as yet unspecified timeframe. Cablevision executives believe the popularity of sports, especially regional sports, could drive HDTV acceptance in advance of its acceptance through broadcast networks.

"Because we have a bandwidth-rich distribution system, we can close the loop on getting high-appeal regional sports programming to customers no matter what the rest of the country is doing," says Marc Lustgarten, vice chairman of Cablevision. "By 1999, virtually all of our New York ADI will be served by 750 MHz capacity networks, which gives us the ability to support HDTV as well as a wide variety of discrete digital programming."

More than just programs

At this point it seems quite possible that cable engineers will be dealing with a larger cable networking dimension to HDTV than that represented by broadcasting alone, possibly even involving more cable programming feeds than broadcast. As Zitter notes, there's a fundamental business imperative behind HDTV that makes moving in this direction an obvious step for suppliers of premium and expanded basic programming. "The initial purchasers of HDTV sets will probably be HBO subscribers," he says.

"Cable guys have enough on their plates already, but it's really important that we as an industry have a strategy where HDTV is concerned," Green says. "As we study these issues, people are going to become more and more concerned. It's a real puzzle when you start to think about it."

No HDTV-related technical issue is more important to cable than figuring out what new functionalities broadcast standard and high definition as well as cable-programmer HDTV feeds will impose on set-top boxes. Initially, cable can expect to pass HD signals through on channel without decoding them at the set-top, given the fact that all HD receivers will be equipped with decoders. Cable interests hope to persuade television set manufacturers to include a QAM (quadrature amplitude demodulation) chip in the receiver, but might ultimately want to perform the demodulation function themselves so as to be able to mix different types of feeds at the set-top, such as might be used in providing a cable-derived data feed to enhance the value of a broadcast HDTV feed delivered in VSB (vestigial sideband) modulation.


Fortunately for operators, consumer electronics manufacturers appear open to cable's needs. "They're generally fairly receptive to having a QAM receiver in the cable-ready HDTV receiver," says Bill Wall, chief scientist for Scientific-Atlanta 's subscriber systems unit. Working with both the Society of Cable Telecommunications Engineers and the broadcast digital-oriented Advanced Television Systems Committee, Wall says he and his colleagues have been in regular contact with consumer electronics manufacturers.

"It's no great leap technically to build a single chip to do both VSB and QAM demodulation, because the two techniques are quite similar," Wall says. However, he adds, "I'm not aware of anybody building this part today."

But merely being able to pass the HDTV signal through to the receiver for decoding won't placate cable's needs for long, says Bob Van Orden, director of digital video systems for Scientific-Atlanta. "It's very hard to predict demand, but I'd venture that it will be the set-top, in our case a next-generation version of the Explorer, that does both HD and standard digital decompression," Van Orden says.

There are two primary reasons operators would want to do the decoding in the set-top rather than relying on the HDTV receiver, Wall notes. For one thing, he says, operators are likely to want to feed the HDTV formatted programming to analog TV sets to expand the market base for highly appealing programming that might not be simulcast by broadcasters in analog iterations.

In addition, he says, "There's an issue with reception of other services with HD programming, such as data content." Boxes like S-A's Explorer are built to support the combining of IP-based data with digital TV, which is seen as the basis for the new generation of interactive programming and gameplaying.

Fortunately, the headend changes needed to accommodate HDTV appear to be significantly less challenging than those involving the set-top and its interface with the TV receiver. "Getting HDTV into the headend and putting it into the QAM modulated channel doesn't present insurmountable obstacles," Van Orden notes. "It's relatively straightforward." In fact, he adds, most stations in large markets are already supplying their TV feeds via fiber and so will present no conversion problems at all for cable headends in their areas.

NextLevel Systems Inc. has begun development of an 8-VSB-to-QAM transcoder that's slated for shipment by the end of next year (see Figure 1). The modules will be compatible with existing headend products and will supply an add/drop multiplexing capability to support operator flexibility in packaging the different types of digital feeds from broadcast and other sources, says David Fritch, senior manager of marketing strategies for digital network systems at NextLevel.


This packaging capability is especially important as the action on the interactive side of the digital house gains momentum. The converging of the forces propelling interactivity, HDTV and standard digital TV has already brought high-speed data and set-top work groups together for frequent discussions at many MSOs and is certain to do likewise elsewhere as time goes by.

"We're all working very closely together to make sure we make the right decisions as we go forward," says Will Richmond, vice president of business development for MediaOne Express, MediaOne's high-speed data unit. "The delivery of video-enhanced types of applications is going to be a key differentiating factor for our services."

The technical components are in place to support a new class of service, typified by a news-on-demand site the MSO is preparing to introduce. Along with local news, the video-enhanced content will include local sports with streamed video clips and other "hometown" content running at up to 20 frames per second (fps) in three-quarter-screen resolution at the PC. This is a far cry beyond the postage-stamp sized, 1–10 fps streamed video clips now available over analog dialup links.

Time Warner's Excalibur group is another high-speed data unit staying in tune with activity on the digital TV side of the company's operations. In May, Time Warner officials and vendors responding to the MSO's request for information covering VOD and Internet protocol-enhanced applications met in Denver to get a better understanding of how the company can exploit the modem and VOD capabilities of its Pegasus set-top box (see Figure 2).

"There's a lot of cooperation going on between our group and theirs," says Excalibur Senior Vice President of Programming Carl Rogers. The focus within Rogers' group is on multicasting, where streaming technology is used to distribute live events, games or other content at specific times to customers, complementing the video-on-demand and HDTV features inherent to the design planning on the Pegasus project side.

"We're really focusing on the service strategy as the way to extend appeal of Road Runner beyond the early-adopter phase," Rogers says. Some unspecified pieces of these new services, with local as well as national content, will soon be tested over various Road Runner systems, with the intention that, by the second or third quarter of next year, the company will be in a position to re-release Road Runner, Rogers adds.

While Cablevision Systems Corp. hasn't announced the vendors for its newly-revised digital TV strategy, its approach is looking a lot like that of Time Warner and MediaOne, where the set-top is designed to handle IP-enabled content components as well as to support delivery of video-on-demand. After testing VOD in a 400-customer market trial over the past year, the company has decided to make movies-on-demand and other interactive services part of the venue as it moves to digital TV, says Wilt Hildenbrand, vice president of engineering at the MSO.

"We're migrating the online data side of the interactive technology into digital TV technology now," Hildenbrand says, declining to specify a rollout date. "With the capabilities that manufacturers are building into the digital set-tops, linking online elements across to the TV is almost root-level stuff."

Better tools for digital

Indeed, with network operators now getting serious about rolling out digital TV, vendors are scrambling to come up with means to add flexibility while reducing the costs of moving signals over networks and processing them at headends. Along with spurring activity among traditional suppliers of headend and set-top gear, the move to digital is drawing in new players, such as Lucent Technologies Inc., which has taken the extraordinary step of moving new digital TV encoding and decoding products into production under the direction of its Bell Labs R&D unit.

"There's still a lot of uncertainty about timing and strategies, but digital is an area we have to be prepared for, because it is an important part of the communications future," says Carl Hsu, vice president of advanced technologies at Bell Labs.

Lucent, like other vendors, sees opportunities for lower-cost, high-performance encoders, protocol convertors, media servers and many other products that are essential to widescale, efficient distribution of digital TV content. "We have to move cautiously because of all the uncertainty that's out there, but we're addressing the needs as they become clearly defined," Hsu says.

Harmonic Lightwaves Inc., too, has added MPEG and other digital video components to its product development activities, recognizing that integration of the pieces with the transmission gear at the headend is essential to lowering costs and making more efficient use of headend space. "We see integration of digital at the headend as a major need in the industry," says John Dahlquist, vice president of marketing at Harmonic.

The company's first product along these lines will be a QAM module that fits into Harmonic's optical transmission platforms, with initial units due for delivery by mid-summer, Dahlquist says. "The QAM modules will take up three rack units of height and be under software control for changing the QAM levels from four all the way to 256," he adds, noting the company thinks it can cut 30 percent off current QAM costs of $5,000–$7,000 per channel.

Similarly, Harmonic is working on integratable MPEG-2 encoder cards with software interfaces for direct management control. "We're designing the product so that 10 encoder cards fit in an eight-rack unit," Dahlquist says, again citing cost reductions over existing gear in the 30 percent range.

Harmonic encoders went into interoperability testing in June, with rollouts slated for later in the year. The initial versions, generating signals at two to 15 megabits per second, will operate at constant bit rates within any given speed domain, with variable bit rate and statistical multiplexing capabilities to be added later, Dahlquist says.

Statistical multiplexing, used in conjunction with variable bit rate encoders, has become a hot development in the push for ever more bandwidth efficiency in the MPEG domain. Now it's moving into the headend.

One of the companies in the vanguard of this effort is Imedia Corp., which has decoupled the stat mux from the encoding process so that operators can add a local MPEG programming or advertising insert into a stat-muxed satellite MPEG feed without having to decode and recode the local signal. "We can take a constant-bit-rate encoded as well as variable-encoded feed," says Adam Tom, vice president of business development for Imedia.

"We're able to separate the statistical multiplexing from the encoding location because we don't require any feedback between the two processes," Tom says. "The encoder can be in L.A., and the statistical multiplexer can be in Denver, which not only cuts encoding costs in managing and packaging content but also allows operators to purchase the most cost-efficient encoders without having to use that vendor's statistical multiplexing system."

Manufacturers remain hampered by indecision about digital strategies on the part of cable operators and broadcasters, notes Lucent's Hsu. But the market message is clear enough now to move things into high gear, he adds.

"All the action is in data and video, so, we as a communications systems supplier, have to go where the action is," he says. For example, he notes, it's logical to assume that Lucent, after working closely with Time Warner and Silicon Graphics Inc. on the now-defunct Interactive Digital Solutions venture, would be ready to respond to calls such as Time Warner's recent RFP for video-on-demand technology.

"I can't comment on specific projects, but you can draw your own conclusions," Hsu says.