Chapter 1

DEFINING TELETEXT AND VIDEOTEX

Computing and communication technologies have joined together to produce a new hybrid technology for delivering home-based information services. The distinctive feature of the technology is not the individual technical elements but the assembly of a total system comprising information banks, indexing structures, computer and communications hardware and software, system management, and billing. Through such an integrated system or systems, millions of people will have access to a wide array of information services-services that can be provided inexpensively, rapidly, and in environments chosen by the user. Because this evolving technology has the potential to change how people use information and indirectly how they think, it may well have an impact on many aspects of daily life as well as on the services currently provided by society.

This assessment is intended to contribute to a fuller understanding of the technological, economic, and social consequences of a widespread implementation of the technology. While our prime focus is on public policy issues, considerable emphasis has also been given to the underlying technological components and to the range of services that could be provided.

There is no single accepted name for this new technology. When referring to two-way information services to the home, terms such as videotex, viewdata, videotext, and interactive videotex are commonly used, while broadcast videotex, teletex, and teletext are often used interchangeably to describe the provision of one-way information services. As if that is not sufficiently confusing, the brand names of various systems themselves have taken on a definitional meaning. For example, Prestel, Telidon, Teletel, Antiope, Viewtron, QUBE, Ceefax, and Oracle are often used to describe the technology itself.

As a result, we have decided to use two generic terms to denote the technology. Following the International Telegraph and Telephone Consultative Committee (CCITT), we use the term videotex as the generic name to describe the provision of two-way information services and teletext for one-way services. In addition, we also use the term videotex to refer broadly to the class of systems that provide electronic information to the home.

WHAT ARE TELETEXT AND VIDEOTEX?

Tyler (1979a) has defined teletext/videotex as follows: "Systems for the widespread dissemination of textual and graphic information by wholly electronic means, for display on low-cost terminals (often suitably equipped television receivers), under the selective control of the recipient, and using control procedures easily understood by untrained users." It is significant to note that with the exception of the term "electronic," the definition is medium free.

Drawing on Tyler's definition, as well as those proposed by Fedida and Malik (1979), Madden (1979), and Winsbury (1979), we can describe the technology as follows:

• It is a broad class of systems, not a single distinct technology. In fact, there is a continuum of sophistication in database information transmission including:

  --scrolling or recorded voice

  --teletext

--videotex-narrowband

--videotex-wideband

--personal computers

--personal computers with fully online database systems

• There is an orientation toward general use or widespread dissemination of textual and graphic information, which is remote from the user.Dissemination or transmission is by one or more electronic means, e.g., telecommunications links such as radio wave, TV signal, coaxial cable, copper wire, optical fiber, microwave, or satellite.

• The information is under user control. Although teletext and videotex have varying degrees of interactivity, neither is a passive medium. Information appears, and transactions are made or messages are sent (and even received) at the express command of the user.

• The system is easily understood by untrained users. That is, it is a system for noncomputing or nonelectronic specialists. This has implications for the way information is accessed, for the way information is packaged and for the way messages are sent and transactions are made.

• The array of services for users is limited only by the ingenuity of those providing them. Teletext and videotex are not just information-retrieval services. They provide an electronic window to a multitude of services in the information society. In subsequent chapters we identify five broad classes of videotex services.

• The system is "low" cost. The whole concept from the original "invention" by Fedida has been aimed at a mass (home and business) market, at widespread implementation. The information services will achieve this status only if they are relatively low cost.

-- information retrieval (e.g., news, weather, sports, advertising, directories, how-to guides)

-- transactions (e.g., reservations, teleshopping, telebanking)

-- messaging (e.g., electronic mail)

-- computing (e.g., interactive games, financial analysis) telemonitoring (e.g., home security)

• It is not a new technology. It is a product of the merging of communication systems and computing. It represents a new combination of hardware, such as computers, databases, communication networks, television sets and terminal devices, and software, including frame design graphics and text, gateways, retrieval mechanisms, and billing.

  These qualities do not, however, preclude videotex, or even teletext, from developing expensive infor-.-nation services for select user groups. While very few people may want to purchase a Mercedes-Benz on their videotex system or to have access to real-time information on the price of greasy wool at the Sydney stock exchange, these services can be made accessible via teletext and videotex. There will always be a market for specialized real-time information and for selective user-group databases, and videotex systems may provide suitable alternative means for accessing some or all of this information. The closed user-group facility on Prestel is recognition of this restricted market use.⁽¹⁾Teletext and videotex as a class of services compete with and could be said to replicate some existing computer-based timesharing services, word processing systems, electronic messaging, and even interactive games. A key element in the systems design is the focus on the household and the untrained user, not the professional computer person. Those services that require specialized training to execute are not included within the above definition, although a new software interface could put such systems into the videotex arena.

  Throughout this project we will refer to teletext and videotex systems as a spectrum from simple one-way transmission, dumb-terminal interaction to sophisticated two-way transmission involving external data networks, intelligent terminals, and the potential for enhanced services.
  
  HOW DO THEY WORK?
  
  Teletext

  Information, consisting of alphanumeric characters or graphic images, is edited on a keyboard or generated from a computer-stored database. It is encoded in a bit stream of digital data at a transmission rate that is compatible with the color-TV system in use (PAL with 625-line pictures in most of Europe, and NTSC with 525 lines in North America).

  The encoded data is multiplexed onto a video signal and transmitted with the TV signal on the unused lines in the vertical blanking interval -- the period during which the scanning of the TV picture begins again (Roizen, 1980). The data in the TV signal are detected by a decoder attached to the TV set as an accessory connected to the radio frequency (RF) antenna socket or directly wired into the RGB beam circuits-- the red, green, blue gun -- of a color TV. The decoder accepts the digital data, stores one or more pages in a buffer memory, and displays these pages on the screen as directed by the user. When the viewer punches the number of the desired page (or screenful of information) on a keypad or keyboard, the buffer memory containing the page is kept in a "hold" condition. The page is then transferred to the TV screen via a character and graphic generator that is part of the decoder. The page remains on the screen until a replacement page is requested by the user or the system is switched off. The information may or may not take up the entire TV display. For example, the information may appear as an overlay to an ongoing TV program.

  The information is "cycled" by the broadcast station. Access time, the delay between requesting a page and seeing it on the screen, depends on the number of pages being cycled, the rate of transmission (the bit rate), the number of TV lines dedicated to carrying the information to the viewer, the amount of memory in the decoder, and the "importance" of the information. (It is possible to make every fifth or tenth page identical so that the waiting time for the information is virtually zero. The pages are slipped into the cycle more often but still exist in the computer in only one place. Alternatively, less popular information may be broadcast only at certain times.)

  For example, using two lines of the vertical blanking interval, 100 pages of text with simple graphics may be cycled every 25 seconds. If a full TV channel were used for teletext transmission, more pages and quicker access could be achieved. In addition, other transmission media could be used to send large quantities of data to a dwelling or business for disc or tape storage. These could include cable TV, cellular radio, low-power TV, multipoint distribution systems, and direct broadcast satellites. These communication transmission networks are described in Chapter 7.
  

  Videotex
  

  As with teletext, pages of information are edited on a keyboard and stored in a computer database. The database design is such that it permits the accessing and rapid retrieval of specific items of information and the billing of customers using the system. The transmission lines between the user and the computer include the public telephone network (using appropriate modems to convert analog telephone signals into digital form for display) or a cable TV system with two-way capabilities.

  Again a modified TV receiver with a decoder translates the data and builds up the video image. As with teletext, the decoder may be plugged into the antenna socket or directly wired into the RGB beam circuits. Pages for transmission are selected by the user on a numeric keypad or an alphanumeric keyboard. As the system has full two-way capability, the user may also send a message to the computer, the database, or another terminal. In telephone systems, the transmission of data to the user is usually at a higher speed than the transmission from the user to the system (e.g., the British Prestel system uses 1,200 bits⁽²⁾ per second from computer to user and 75 bits per second from user to computer).

  The significant difference from teletext is that with a videotex system the data is not routinely cycled in a broadcast mode; instead, the individual users access the database as required. Thus, access time is now a function of the processing capacity of the host computer and the volume and pattern of usage.

  From the above system descriptions it is evident that there are four general actors in any teletext/videotex system: the users of the service, the communications network provider (e.g., a common carrier or a broadcast station), the teletext or videotex system operator (e.g., the broadcast station or a private corporation that operates the teletext or videotex system), and the information service provider (e.g., any private corporation or public agency).
  
  WHAT IS THE MARKET FOR THE TECHNOLOGY?
  

  The key research question of this study-- What are the public policy consequences of widespread implementation of teletext and videotex? -- presumes the existence of a consumer and/or business market.

  The potential consumer market is every household with a telephone or a television receiver-in excess of 98 percent of all U.S. households in 1980. As the technology utilizes existing home-based components, its "newness" has more to do with the way in which things may be done and the juxtaposition of the components than with the technology itself. Even so, American Telephone and Telegraph estimates that the market for telephone-driven videotex will not exceed 7 percent of U.S. households by 1990 (Sullivan, 1981). On the other hand, cable TV penetration (actual homes hooked to cable systems) is forecast to rise from the current 28 percent to more than 50 percent by 1990 and to "pass over" 75 percent of households. While virtually all existing cable systems are one-way only, most new franchise bidding includes provisions for two-way interactive services.

  There may be other incentives to market teletext and videotex terminals. economics of paper-based directories and manually operated switchboards, for example, have led the French Postal, Telegraph and Telecommunications Department to undertake a long-term project to replace paper directories with electronic directories. A cost/benefit exercise in the United States may lead to similar conclusions. The declining cost of microprocessors suggests that with large-scale production, equipping television sets with or without teletext and videotex decoders will be comparable to the price of other options. For example, a teletext-equipped 12-inch-screen color TV might cost the same as a 21-inch set without teletext. Advertising and marketing strategies may further "encourage" TV purchasers to switch to an enhanced set.

  One further possibility is the use of videotex systems for fire and burglar alarm services. While not a traditional information service, it is a natural application for the electronic link from the home to an external computer and database.

  At present the only commercial systems in operation in the United States provide teletext and videotex services directed at special groups such as captioning for the deaf, Dow Jones financial information, and home-based personal computer services (The Source, CompuServe). As teletext and videotex systems offering a variety of electronic services are introduced, and as user-friendly protocols are developed, the potential markets for the technology will expand. Our intention in this book is to examine the plausibility of widespread penetration within a 20-year time frame and to assess the public policy consequences of such developments.
  
  
  1. A closed user group is simply a number of users of a particular restrcted system. Membership in the club is esential to access rthe service (i.e., a stockholder investment service or a list of entertainment activitiues in Payboy Clubs). On Prestel the term "closed user group" refers to intracompany restrictions on access to data; "syndicated closed user group" is the more general term for restriucrted groups. Back

  2. A bit is a binary digit (one that takes a value of 0 or 1). An 8-bit unit is referred to as a byte. A kilobyte, kbyte, is 1,000 bytes and a megabyte, Mbyte, is 1 million bytes. Back

   

   

1/30/97