A New Partnership after a Long Separation

Public broadcasting and distance education have had a somewhat mixed relationship over the years. While most PTV stations started out with strong distance learning missions, the last two decades have seen a move away from formal "educational broadcasting."

This parting of public television and distance learning is about to end. Digital television, soon to be implemented in most of the nation's major cities, and across the country by 2006, will provide each station not only with an opportunity to deliver high-definition wide-screen pictures, but also multiple narrowcast channels, and a one-to-many digital data capacity equal to the best cable modem or ADSL circuit. This convergence of television and computing, broadcasting and the internet, will stimulate a demand for new programming genres - a demand that will encourage new partnerships between public television and university-based continuing and distance education organizations.

What is DTV? And how might educators use it?

* DTV sends a compressed digital signal in the same channel space as today's analog TV. The new digital broadcasting standard for North America provides for the replacement of our fifty-year plus analog broadcast channels with a new set of digitally-encoded 6 megahertz-wide allocations in the UHF band. Each channel will carry a combined data stream just under 20 megabits per second. This is equivalent to nearly 400 "56k" modem channels or a dozen T-1 lines. In order to fit immense amounts of digital information required to encode high-quality motion video, the signal is "compressed" for storage and broadcast. The compression scheme (MPEG-2) is the same one already being used for CDs, DVDs, high-end web streaming and most satellite broadcasts.

* DTV will deliver stunning images and sound in a wide-screen format. Video compression technology makes it possible to deliver much more picture and sound information than is possible over today's analog channels. DTV's "high-definition" specification provides for a video signal containing over 2 million pixels, six-times that of the best analog studio camera.

Standards Comparison Table

NTSC (analog) HDTV (digital)

Total lines 525 1125
Active lines 486 1080
Sound 2 channels (stereo) 5.1 channels (surround)
Aspect ratio 4 x 3 16 x 9
Max. resolution 720 x 486 1920 x 1080

* Wide-screen images will be displayed in a 16x9 ratio (at either 1080 interlaced scanning lines or 720 progressive lines). While the bulk of "HD" broadcasts will consist of sporting events, movies, nature programs and arts events, once HD sets and recorders drop in price and all stations have converted to DTV, educational programs requiring high resolution images (e.g., in the arts, medicine, engineering) will soon become economically possible. Satellite feeds of medical grand rounds, meteorological engineering courses containing complex 3D weather models, will find their way on to instructional DTV broadcasts.

* DTV will give each broadcaster multiple narrowcast channels. Because HD programs are so expensive to produce, and much content does not require a wide-screen display, most stations will use their DTV capacity to increase the number of program options being broadcast at the same time. While commercial television is worrying about the effects of "audience fragmentation" on advertising revenues, public broadcasters are talking about their ability to finally serve their multiple audiences with dedicated services. A full-time adult learning channel is clearly one option. Hybrid services, combining 1-way video with internet-based interaction opportunities will blossom as DTV receivers add more internet features and as PCs become more like TVs. Informational and instructional content will drive these new mini-channels.

* DTV provides a one-to-many, real-time, high-speed data-delivery channel. DTV is transmitted as digital packets; since not every packet in the channel is needed to carry television information, the extra capacity is always available for other digital services. The good news is that as far as DTV is concerned "a packet is a packet," whether it contains audio information, computer programs, email, web screens or commands to turn on the microwave oven! This means that any program created by educators for delivery over digital media CD-ROM, IP web stream, etc.) can be "streamed" over DTV's data channel to any individual receiver or all receivers in the coverage area. Even when carrying HD signals, at least 1 Mb/s will be open for datacasting; when stations are transmitting less demanding signals, greater capacity for datacasting becomes available - up to the full 19 Mb/s if no TV is being sent out. Imagine the ability to download fully-updated interactive educational materials to thousands of PCs (or tomorrow's next generation of TV/data recorders) simultaneously!

* DTV makes a new genre of "enhanced television" possible. The most exciting opportunity for bringing public television producers and university educators together, lies in DTV's capacity to bring together its television and its data signals in an integrated "enhanced video" program. PBS has already demonstrated how a broadcast program can carry an entire CD-ROM's worth of supporting pictures, text and audio to a DTV-capable multimedia PC. Last November's digital broadcast of Ken Burns' biography of Frank Lloyd Wright also carried a companion program, invisible to most viewers, but available immediately after the program at the click of a mouse. A number of enhanced programs are already being planned for PBS distribution during the DTV phase-in period: www.pbs.org/digitaltv/tune.html

While these national DTV efforts will be getting most of the publicity, enhanced TV provides an opportunity for continuing education partnerships to be developed at the local station level. Each local program will have its own "enhancement stream" - providing information, education and instructional content to meet the learning needs of different audience segments - from those that only want to order a companion book to the series, to those that want additional information and access to extended interviews and related visuals "left on the editing room floor"; to those that are seeking more serious interaction with the content - from joining a discussion group to registering for an online seminar. Instructional videos will all be able to carry a full multi-media enhancement package, delivered at high speeds to students across the nation.

Continuing and distance educators and instructional video developers need to think about the impact of digital TV convergence - for it will provide more than just new channels for transport. It will also provide opportunities and challenges in content development, production techniques and content marketing partnerships.

Suggested Links:

For a non-technical "crash course" on DTV, see Robert Cringley's DTV Intro: www.pbs.org/opb/crashcourse on PBS Online. For a discussion of possible PTV and Continuing Education partnership, see my "Beyond the Portal": www.cpb.org/library/infopackets/packet35.html; for review of current "enhanced TV" projects using WebTV for Windows, see also my "Looking for DTV Models" article for CPB" infop@ckets: www.cpb.org/library/infopackets/packet34.html. For a list of how DTV may change the PBS Adult Learning Service, see: www.pbs.org/digital/TV/teach2.html#adult.

(Steven Vedro - srvedro@facstaff.wisc.edu - is an independent Educational Telecommunications Policy and Planning consultant based in Madison, Wisconsin. A number of his writings appear on the Corporation for Public Broadcasting "info.p@ckets" www.cpb.org/library/infopackets/packet.home.html web site)