DTV: A New Tool for Education?
Digital Television:
A New Tool for Education?

Andy Carvin
Corporation for Public Broadcasting
Tel-Ed '98, New Orleans, 30 October 1998

(slide presentation is also available)

Hello, thank you for coming. My name is Andy Carvin and I'm with the Corporation for Public Broadcasting. Today I'm going to talk about a new technology that's coming just around the corner - a technology known as digital television. There's a good chance you've heard of digital television by way of its many names: DTV, HDTV, Enhanced TV, and so on. For example: Until very recently you'd most commonly hear the term HDTV, or high definition television. Most of the talk around HDTV centered on its high resolution video and digital audio - such high quality that it would impress the pants off of anyone. But besides that, you probably don't have much of a sense of what the technology is all about. What's DTV, and why should I be interested?

In a nutshell, DTV is the first major change in television broadcast standards in 45 years - the first since 1953 when the US adopted the RCA color television standard. Unlike current broadcast television, digital TV - as the name suggests - will transmit and receive broadcast signals in digital. I know some of you are probably thinking, "So what?" How is this new DTV going to be different from my current TV? Well, let's start off by taking a quick look at the difference between the current analog television broadcast versus the digital TV broadcast:

Figure 1: Analog broadcasting

Here we've got a simplified picture of how broadcast television works nowadays. In step one, you've got to start with an audio/video signal you want to broadcast. In this case we've got a picture of Barney in the studio getting videotaped by a cameraman. There's no reason this first step has to be live in the studio, though - you could certainly take pre-recorded material on a video tape and broadcast the tape material instead. Either way, the audio/video signal is then broadcast through a large antenna tower, as seen here. Nowadays a lot of people receive TV by way of cable, but the principle is still the same - you have a signal to broadcast from one place to another. If you've got an antenna on your house you'll pick up the broadcast signal as a series of radio waves that your TV will convert into the audio/video broadcast. And with that, you end up with Barney appearing on your TV screen.

It's a simple process: broadcast TV has been around for 60 years but the basics of broacasting are still the same. Digital TV, on the other hand, is going to be just a little different, but different enough to revolutionize the way we use television. Let's take a look at our second example:

Figure 2: Digital broadcasting

Once again, we've got Barney in the studio, and once Barney has been taped and edited, the signal is then broadcast from an antenna tower. But if you notice the signal going through the airwaves from the antenna tower to your home, you'll see something has changed. We no longer have the traditional radio wave signal carrying the broadcast to your home. Instead, the digital television broadcast will transmit binary code: a series of 1's and 0's, just like the all the data you have on your computer, on the Internet, on a music CD. This signal of 1's and 0's is then received by your antenna and decoded by your television in order for you to view it.

So what's the difference between analog and digital TV? Well, as we migh say back in Washington DC, it's the 0's and 1's, Stupid. (laughter) Digital transmission completely changes the way people see and experience television. The most obvious difference is that you'll now be able to receive high-definition TV broadcasts. Just as digital encoding allows a music CD to sound clean and crisp compared to an audio tape or record, digital television broadcasts allow for a incredibly clean and crisp audiovisual reception. If you've ever seen HDTV, you know that the first thing you notice is the incredible image and sound quality. It's all because digital technology is designed to correct errors that may occur in the broadcast transmission process. So when you receive your DTV signal it will be just as clear, just as strong as the originating signal itself. It doesn't even matter if you're 50 miles away - if your antenna can pick up a DTV signal in the first place, it will still come through just like new.

Another difference you'll notice is that DTV uses a wide-screen format:

Figure 3: Traditional TV vs. Widescreen

If you look at the way TV appears today, you'll notice there's a certain rectangle used for each and every TV screen: a four by three ratio. In other words, for every four inches across your screen will also be three inches high. DTV, on the other hand, will use a wider format: 16 by 9. This ratio should look familiar because it's similar to the wide-screen aspect ratio used in movie theatres. So DTV's wider aspect ratio will make it more attractive for broadcasting cinematic content.

One of the main reasons DTV will have such a crisp image is because the screen resolution will increase significantly. Digital broadcasting is extremely efficient, much more so than current analog broadcasting, so you can pack in an increased number of pixels per screen. So unlike today's TVs, which broadcast at 525 horizontal lines per screen, DTV will allow for as many as 1080 horizontal lines. That's over twice the resolution of analog TV. So even if you stick your face right up to the TV you'll still get a high-res image because there are so many lines of data making up the full image.

DTV's high level of efficiency will also allow for what is known as multicasting. Multicasting is simply taking one transmission channel and squeezing multiple program signals into it all at the same time. For example, if you turn on your local PBS station on channel 11, you'll only get one option for content - whatever's being broadcast at that moment. But if channel 11 were to broadcast in digital they'd be able to transmit as many as four or five different programs at once, giving you multiple viewing choices. There's no hard and fast rule as to how many programs you could multicast over a channel - it could be two, it could be eight. It all depends on the bandwidth needed for each program: high-resolution programs take up more space than low resolution programs, so the broadcaster must figure out how they want to utilize the space they have available. No matter what, though, the technology will let you broadcast multiple signals if that's what you want to do.

The last - and perhaps most important - difference with digital and analog TV is that DTV will allow you to combine TV signals with other types of digital content. Conceivably, any kind of information you can crunch down into 1's and 0's can also be sent via DTV broadcasts. For example, you could broadcast computer software, database content, even Internet content. DTV signals could also be used to transmit webpages - literally thousands of pages if you wanted to.

But how much information can you send? A lot, to say the least. DTV signals will be broadcast at 18.3 megabits per second. Megabits. If you compare that to a 28.8 modem, that's 635 times faster. So conceivably if you were using all of your DTV spectrum for multimedia content, that data would be sent over the airways at 635 times the speed of a 28.8 modem. For all practical purposes, though, data transmission in its own right won't be that fast, since broadcasters have been mandated to use at least some of their DTV spectrum for television broadcasting. One possible example would be for a broadcaster using half of the spectrum for TV signals and the other half for data - that's still as much as 9 megabits for data transmission. It all boils down to what you want to squeeze through your channel and what you're trying to accomplish. So if you are solely interested in multicasting you could spend all of your bandwidth on four or five tv program streams. Or you could use all of your bandwidth for one high definition signal. Then again, you could transmit one or two standard definition signals and use the rest of the space for data. There's no one single rule for utilizing DTV spectrum - broadcasters will have to figure out for themselves what method is best for them. But there are so many options: if you can take content and convert it to 1's and 0's, you'll be able to send that content through the DTV signal. It's just a matter of figuring out what kinds of content you'd want to transmit.

So when is all of this coming? Tomorrow? Nope, but you're really, really close. The world of DTV is actually coming the day after tomorrow - November 1, 1998. Seriously. November 1 is the date on which the top 10 television markets must begin their transition to digital. By top 10 markets I mean the 10 largest viewing audiences in the US: New York, Chicago, Los Angeles, and so on. Starting this week they'll begin the process of switching to digital. Now this doesn't mean that you'll no longer be able to receive your current analog TV signal - analog signals will continue for many years to come. November 1 is simply the date when the transition begins. By May 1999, every commercial broadcaster in those top 10 markets will have to complete their digital transition. With each passing month, more and more markets will make the switch: first the top ten markets, then the top 20, top 30, and so on. By November '99 we'll be up to the top 30 markets. Smaller market stations will take longer to make the switch so they're given extra time. But by 2002, all commercial network stations will need to be finished with their digital conversion process.

Public broadcasters, on the other hand, will have even more time: they'll need to get the job done by 2003 (though many PBS stations are pioneering certain DTV efforts even today). Once the transition is complete, we'll be left with all of these analog TV channels that will then be considered obsolete. If all goes according to plan, in 2006 the commercial networks will return their analog TV spectrum back to the FCC, who will probably auction off the spectrum to the highest bidder. Public broadcasters, might be given a break and be allowed to keep their analog spectrum - the idea has been proposed by some the Gore Commission on DTV public interest obligations, but it's not official yet. If it were adopted, though, the extra spectrum would give them even more opportunities to experiment with broadcasting technologies.

Whenever I give these presentations on DTV one of the first questions out of the audience's mouth is "How much is this gonna cost me?" There's certainly be a lot of talk in the press about these giant high definition TVs costing upwards of $7000 or more. Unfortunately that's true: it's a brand new technology, it hasn't been adopted by many people yet, so for the time being HDTV is going to cost a lot. But $5000 or $6000 per TV shouldn't scare you because if you go back to the 1950s when the first color TVs were coming out, these TVs cost as much as $6000 in today's money if you factor in inflation. These boxes weren't cheap. But as more people invested in TVs, the prices dropped significantly. Price points drop in practically any item as that item becomes more common and more available. After a few years the color TV became more affordable to the average family. The same decrease in costs will probably occur with the advent of DTV as well. It may not happen overnight, but given enough time and interest, the prices will drop.

If HDTV's don't get cheaper, though, you've still got several options. First, you could buy an SDTV, or standard definition television set. The SDTV will be a TV similar to the one you have now, but it will be fully compatible with DTV signals. You won't get the high-resolution of HDTV but at least you'll get the DTV signals, including multimedia content. These SDTVs should start appearing on store shelves this holiday season, and they probably won't cost too much more than your current analog TV. If you want to get even cheaper you can purchase a set-top box. These are little tuner devices that sit on your analog TV just like a cable box. These boxes will probably start around $150-$200 and will undoubtedly get cheaper over time. The last major option would be to buy a DTV tuner card for your PC. The tuner card would make DTV signals accesible to your computer. Essentially, your computer will be your television - the technologies will begin to blur. Most people will probably start their DTV experience by buying either the set-top box or the tuner card. As HDTV prices drop they too will become more common but until that happens most consumers will have to accept a half-way solution.

So now that I've been blathering on for 20 minutes I can only imagine you're wondering, "What on earth does all of this have to do with eduction?" I'll be honest, though - I really don't know the precise answer. But then again, none of us really know how DTV will impact education. It's such a new medium, no one has it in their homes yet, few people are producing for it yet. We're just coming up with concepts, theories and ideas of what digital TV will look like and how it might be used in education. We've got some notions of where DTV is going to go, but it's gonna take some time for us to sort it out.

Just to get your minds thinking I'm going to play you a demo produced by WNET for its program, Great Performances. The demo will show off some of the possibilities of enhanced television. I should probably note that this demo was designed with a general audience in mind and not an education audience, but I think the demos will give you a sense of where DTV might take us.


So now you should have a sense of the types of DTV content people are beginning to think about. As you probably noticed, while the demos might serve as possible services for a general audience, it's hard to pin down exactly how they might be used in an educational context. But the demos should at least give you a sense of DTV's multimedia capacity. So what we need to do is explore these ideas a little further and expand on their possible application in education.

One possible use of DTV in education would be what is sometimes known as enhanced TV. The Henry V demo is a good example - you've got a television broadcast supplemented by multimedia content. The multimedia content could be webpages, quicktime movies, text scripts, etc. There are a lot of possibilities in terms of how enhanced TV could be applied in an educational context. On November 9 and 10, for instance, PBS will broadcast Ken Burns' latest documentary, Frank Lloyd Wright. Now all of you who can receive PBS at home either through cable or an antenna, you'll still be able to receive the documentary broadcast. But in six communities around the country, local PBS stations will broadcast multimedia content along with the documentary. The multimedia content will be downloaded to your DTV or your computer in real time, allowing you to access it either during the broadcast or after the broadcast. In this particular case, the multimedia content will include 3D fly-throughs of Wright's most famous buildings, including the Guggenheim Museum and Falling Water. You'll also be able to pick up film footage of an interview with Wright conducted by Mike Wallace in the 1950s. Finally, Wright's grandson has contributed video clips discussing what it was like growing up with his famous grandfather. Until now, there would be no way you could have received this multimedia content as part of the actual TV broadcast. Digital TV changes all that.

Frank Lloyd Wright is the first of many DTV experiments that will undoubtedly come around in the near future. Just to give you some more examples of the types of enhanced TV you might receive:

NOVA, PBS' science documentary series, is an excellent candidate for enhanced TV. They're already doing multimedia on the web, so DTV would be a natural step forward. For example, last season NOVA broadcast a series called Secrets of Lost Empires. The series focused on famous ancient engineering feats such as the building of the pyramids and Stonehenge, and explored the practicality of raising these monuments without the aid of modern equipment. If this series were broadcast in 1999 instead of 1997, they might include educational simulations that would allow users to attempt to raise their own virtual Stonehenge or construct a virtual pyramid. The software would allow the user to experiment with the number of people pulling on a particular rope, the weight of the rock, the angle of pulling, the size of the A-frame, and so on. By applying rudimentary physics principals, a student could hypothesize what would happen when a given set of variables were placed into the simulation. In one situation you might raise the lintel piece to its proper position, while in another case you might accidentally squash 50 of your men because you underestimated the manpower needed to raise the stone. Before DTV, you would have to purchase a companion CD or use the Web to conduct these experiments, but with arrival of digital broadcast you'll be able to receive this multimedia content directly through the airwaves.

Another good example of enhanced TV would be the program Great Performances. In the WNET demo you can see a simulation of a user selecting different angles from which they can view the performance. Imagine taking it several steps further: while you watch the broadcast you'd also receive a musical score in another browser window. With this score you'd be able to isolate the sound of different instruments, experiment with changes in the score, rearranging the music itself. A music student could use the enhanced TV program to learn more about how a symphony combines different instruments, the use of harmony and counterpoint, and so on.

A second use for digital TV would be what might be called Broadcast Web or datacasting. Because DTV gives you the ability to broadcast websites and other multimedia content, you could send an enormous amount of content through the airwaves without requiring the user to subscribe to an online service or to have a wired computer connected to a high-speed Internet connection. Schools that don't have high speed connectivity could easily purchase DTV tuner PC cards for their computers or set-top boxes for their televisions. With those technologies alone they'd be able to receive datacasts of Internet content. The same opportunity applies to the home: We've got millions of people online today but the majority of US citizens don't have Internet access at home. However, the majority of homes do have TV sets - over 95% of all households. So if a family were willing to invest in a set-top box they would then be able to receive Internet content at home. Broadcast-based web content opens the door to millions of families that previously were considered the have-nots of the information society.

Third, we have the issue of DTV and professional development. About six months ago I conducted a series of interviews with educators around the country, explaining what DTV was, how it's going to work, and so on. I then asked them, "Now that you see what DTV's all about, whaddya think? Does it have educational potential?" Invariably, almost every group of teachers responded by saying they wanted to have professional development services available over DTV. They wanted to be able to learn at home, on their own time, at their own pace, giving them the flexibility to improve their teaching skills as they needed it. It's certainly a possibility: A broadcaster could transmit professional development content over the airwaves, allowing the teacher to receive it at home.

And it doesn't have to be TV content only - a teacher could utilize professional development software, websites, and other services as well. For example, imagine you're a middle school math teacher and you're looking for some new ideas for teaching introductory algebra, you could turn on your DTV, look at the professional development program guide and select a relevant program by dialing a 1-800 number and submitting the appropriate code. Within a given amount of time the broadcaster would then find the content and broadcast it, allowing you to receive it and store it on your DTV for use at your convenience. And because DTV is broadcast like any other TV program, an entire school district could receive educational content as long as the district fell within the station's broadcast area.

Additionally, it would be possible for individual schools to contribute content to a professional development best practices database. If your school has a particular success story to share, you could videotape the story and transmit it to the broadcaster, who would then make it available in the professional development archive. From that point on, any other school that was interested in your best practices could then request a copy of the footage and receive it in a timely fashion. And the more schools can contribute their best practices the more powerful the database gets.

Again, we don't know exactly how this new DTV technology is going to work, but there's a solid possibility that some of these applications could be both feasible and desirable. We'll only know by trying and seeing what happens.

So what are the obstacles and limitations of DTV? Unfortunately there are a lot of issues we need to consider. The most obvious obstacle is cost. We keep hearing about the $6000 HDTV set - how on earth can I afford that? Well for now, you may not be able to afford it. We've got to hope that consumer demand will push the prices down, but it ain't gonna happen overnight. You also have cost issues with the set-top box and the PC tuner card. In the case of the set-top box, $150 may still be too much for the families who need the technology most. What are we going to do to lessen the gap? There are several options, including low-cost rent-to-own offers or giving students the boxes as part of their schooling or tuition. If a school district bought these boxes en masse and made them available to families at $5 a month, more people would be able to afford them. PC cards aren't an instant solution either, even though they cost only $100. If you're going to buy a card, you'll first need to have a Pentium II computer, and that will set you back at least $1500. Your PC card will be useless without it. For those families with computers, it's a cheap solution, but for those families without computers, it's a waste of money.

The next issue we need to consider is content availability. There are only so many producers out there who are currently producing for the digital market. A lot of people are taking analog TV programming and retooling it for digital, but they're not producing content specifically for the new technology. Are consumers really going to want to buy DTV technology when so few producers are creating content for it? Probably not. Certainly there are those early adopters out there who'll want to be the first kid on the block with the HDTV set, but the average family won't rush out to buy DTVs until they know there's programming available for it.

DTV is also a one-way information stream. Because DTV is broadcast similarly to tradition broadcast television, it's only going in one direction: from the station's antenna tower to the home. You won't be able to send content in the other direction - at least not in the exact same way, since DTV spectrum can only be used by licensed broadcasters, not consumers. So in order for DTV to be interactive we'll need to utilize some kind of back channel. A lot of people are now suggesting that the Internet will be the primary back channel, and I think that'll be the case for at least the near future. For example, a school may have a 56k ISDN line to the classroom. If that classroom has DTV as well, they might be able to receive Internet content at megabit speed and then respond to web content by way of that 56k line. Their upstream data won't be as fast at their DTV reception but at least they'll have some interactivity. Other back channel possibilities include wireless communication, spread spectrum, cable modems, etc. It's all going to depend on how the market responds to DTVs when they start appearing in peoples' homes. Until then, though, I would bet that the Internet will serve as the primary back channel for DTV communication.

The next obstacle we need to consider is the slow rollout to DTV broadcasting. As I noted earlier, DTV is literally going to start this weekend: Sunday is the day when stations in the top 10 markets will begin their transition to digital. But it's going to take a long time for every broadcaster in the US to make the transition. It's not cheap: conversion will cost anywhere from $2 million to $10 million depending on the size of the station. A lot of rural stations, a lot of smaller market stations will have some difficulty making the transition on time. The FCC has mandated a timetable for stations to convert from analog to digital, but in all honesty, what are they going to do if scores of stations simply can't do it on time? They'll probably have to postpone the deadline. Chances are there will be many stations that don't have the money, don't have the experience, and don't have the interest in changing to digital on time. What are we going to do about it?

We need to consider the issue of commercialization. It's happening right now, here on the Internet: as soon as a new telecommunications medium becomes accessible to a significant public market, you begin to see the signs of commericialization creep in. Every Internet company and their dog is trying to figure out how to make a buck off of this new technology, off of this new market. It's become a matter of course that people want to make money off of the growth of the Internet. The same thing will undoubtedly happen with DTV, especially with the major TV networks - ABC, NBC, CBS and Fox. The transition to digital isn't going to come cheaply, so the networks will do what they can to make that money back. So if you were a big network and were thinking about how to profit off of digital TV, would you focus your efforts on educational content? I highly doubt it. It's difficult to get a return on investment when it comes to educational programming. So does this mean that DTV will simply mimic commercial analog TV or the commercialization of the Internet? To a certain extent that's probably going to be the case, so how can noncommercial broadcasters and public broadcasters take up the slack?

Finally we have the issue of DTV shovelware. Shovelware is simply the notion of taking content developed for one medium and then dumping it into a new medium without really thinking through how your content really fits into that new medium. What's going to happen when DTV becomes available? Will producers sit back and think, "Here's this revolutionary new medium - let's invest in a lot of R&D and come up with brand-new techniques for utilizing it." Some producers hopefully will, but it's all to easy to take previously developed content and dumping it into DTV without making an effort to create something totally new. Shovelware saves producers a lot of money, a lot of effort. Unfortunately it's not very revolutionary, it's not very educational. Will producers be willing to invest in new prototypes or will they fall back on the same old stuff?

There's a lot of potential in digital television but there are also a lot of excuses for us to not take advantage of it. Considering the birth of the medium officially comes later this week, it's difficult to say exactly how the advent of DTV will play out over the long term. But because this is the moment of creation for this new medium, we've got the opportunity to start thinking outloud how DTV can be utilized best in education. Remember: November 1, 1998. Two days away, no turning back. This is our chance to get ahead of the game and explore DTV's possibilities before it's too late.

So what can we do to leverage the power of DTV in education? First, we need to spread the word about DTV. Most people aren't thinking about DTV yet, and if they are, all too often they've got HDTV on their minds and have no sense of its multimedia potential. As I've explained today there are clear-cut possibilities for utilizing DTV in education - we just need to begin to articulate what those possibilities are.

Second, I'd encourage you to get in touch with your local public broadcaster. All 348 PBS stations are getting ready to make the switch to digital. And as they make the switch they'll need to think hard about how they want to spend their bandwidth, how they want to utilize it in their communities. Stations need your input - they want educators to articulate the role they see DTV playing in their communities. It might be a professional development channel, it might be broadcasting kid-friendly webpages. Public broadcasters are already thinking about these issues but they need your input; they need to know there is a market in your town for such services.

Third, we need to find ways to encourage people to come up with revolutionary ideas. There are a lot of good ideas out there, maybe even a few great ideas; but so far, there aren't any truly revolutionary ideas in terms of how DTV can be exploited as a totally new medium. It's still too early because we've got so few people thinking about DTV content. So we need to get more people from more fields - education, community development, the arts, local businesses - involved in the content brainstorm process. If we don't think about the possibilities of digital, the commercial TV networks will. We could reach the point where DTV is history repeating itself: 35 years ago, FCC commissioner Newton Minow labeled television a "vast wasteland." Fortunately services like PBS have improved the face of television, but beyond that, little has changed. A lot of people also thought that the Internet would be a massive tool of democracy and learning. In certain ways it has, but in many other ways it's become just as commercial as any other medium. Once again, we're at the point where a new medium - DTV - will be the tool we use to create educational, noncommercial oases in a vast wasteland of commercial content. But if we don't take advantage of it, we'll soon be left with yet another medium overtaken by the urban sprawl of commercialization and mediocrity. It's up to us to make an effort and make the most out of it.