VIDEOTEX ALTERNATIVES IN CABLE Walter s. Ciciora William L. Thomas AMERICAN TELEVISION & COMMUNICATIONS CORPORATION ZENITH RADIO CORPORATION Introduction without increasing bandwidth. VBI teletext services are available on any The first videotex alternative systems that carry WTBS, NBC or CBS. determines whether the transmission is Both NBC and CBS are currently broad­ broadcast, telephone, or cable. The casting teletext according to the North concentration here is on cable. The American Broadcast Teletext Specifi­ reasons for this will be discussed in cation (NABTS). WTBS carries the Keyfax detail since they are fundamental to signal which follows the British understanding cable's substantial advan­ approach. Unfortunately, two different tages over competing media. In cable decoders would be required to receive there are a wide variety of alternatives all three signals. Full field teletext to consider. Should the videotex ser­ requires the dedication of a complete vice be vertical blanking interval or video channel to the teletext service. full field? Will financial support come In return for this commitment, full from advertising or from pay, or both? field teletext offers tremendous page If a pay structure is chosen will the capacity. Typical systems can carry 500 security be soft, firm or hard? Will or more pages per second. This is in the service be tiered and addressable or contrast to the 4 or 5 pages per second simply go no-go? Will it be one-way, possible in a VBI service. Thus, for a one-way upgradable, or two-way? Will given 10-second maximum wait time, full the display be RF or RGB? Are mosaic field teletext has a capacity of 5,000 graphics adequate, or must geometric pages. This contrasts with a 40 or 50 graphics be employeed from the very page capacity for a 10-second wait in a beginning? Plain or fancy? VBI system. Two examples of full field teletext systems are at the conven­ VBI vs. Full Field tion. The Time Videotex Information Service (TVIS), is a full featured, high Vertical Blanking Interval (VBI) resolution graphics service with the cable teletext is basically an ancillary emphasis on quality contents. Zenith service. Like its broadcast cousin, it has made available a full field tiered has limited capability. Unlike the addressable teletext set of equipment broadcast environment, however, cable with the emphasis on lower cost and more has multiple VBI's under the control of immediate availability. The TVIS system the same entity. Thus, tiering can be has been created by experts in publish­ accomplished by putting information on ing and information communications. The various subjects on different chan­ Zenith system has been created by nels. Cable will not have the multipath hardware experts. problems that broadcast does. The Keyfax service is a right-now example of Advertise or Pay VBI cable teletext nationally distri­ buted in the Vertical Blanking Interval Two mechanisms of financial support on Channel 17, WTBS, Atlanta. Keyfax is are proposed. Advertiser support is the on exhibit at the convention and equip­ more conventional method used in broad­ ment is available now on a limited cast television. Advertisements are basis. VBI teletext makes the most introduced either in a intrusive or non­ sense in older cable systems which have intrusive manner. The intrusive ads are 12 to 24 channels and cannot afford a unavoidable. They appear as messages on fully dedicated teletext channel. A 12 a page containing desired information. channel cable system which used its 12 The non-intrusive ads must be specifi­ VBI's for separate data services, could cally pursued. The advantage of a non­ offer significantly expanded service intrusive ad is that it serves a cus- 166 torner with a serious need. The advan­ configuration of services. This quickly tage of a intrusive ad is that it becomes economically untenable. Tiering attracts attention. is the process of dividing the service into segments. Tiering is merely the The alternate method of financial application of the market segmentation support, is a pay service. This is akin principle. It allows the subscriber to to the method of support employed in tailor the service to his individual premium cable services. In order for a tastes and needs. pay strategy to be successful, access must be restricted. There are at least The Graphics Choice three approaches to restricting access. Soft security relies on the scarcity of The TVIS full field teletext service equipment to restrict access. This and the NBC and CBS Vertical Blanking technique has been employed by Keyfax. Interval services are based on geometric The advantage is simplicity. The dis­ graphics. High resolution displays advantage is that if teletext becomes provide eye appeal which is felt neces­ successful in the broadcast environment, sary, particularly in advertiser sup­ teletext receivers connected to cable ported systems. The Keyfax and Zenith will obtain the Keyfax service for systems are mosaic graphics based. free. This will require a change in the Arguments over the relative costs and Keyfax support mechanism to an adver­ relative desirability of different tiser-based approach or a switch out to graphic systems, have been carried out different hardware. The Zenith system in the literature and at conferences uses a firm security mechanism which over the last several years. There is introduces a modest amount of scrambling no need to repeat any of that here. The of the data. A commercially purchased passage of time will determine which broadcast teletext decoder will not be approach survives. It is conceivable able to decode the Zenith scrambled that the marketplace has room for both. signal. The ultimate in security and cost is a hard scrambled system based on NTSC vs. RGB Display advanced digital techniques, such as the Digital Encryption Standard, created by Two mechanisms for displaying the the National Bureau of Standards. Soft teletext information are possible. One security has a limited lifetime. One of mechanism connects the decoder to the the principle disadvantages of soft antenna terminals of a television set. security in a pay system is the fact The other uses a specially modified that stealing the box is very rewarding. television set or a video monitor. The It provides free service for the length latter approach, while more expensive, of time the information provider avoids yields a better display because the red, Chapter 11. Firm security is an blue and green guns of the picture tube economic compromise which restricts can be driven directly. The quality of access but avoids the cost of true hard this RGB drive is limited only by the security. characteristics of the picture tube. Going through the antenna terminals of a Tiered Addressable television set enforces all of the corn­ promises made in creating the compatible The tiered addressable concept is a NTSC color television system. The fundamental lesson learned by the cable recent availability of video monitors industry in recent years. If a service with RGB inputs has been stimulated by is valuable, it must be controlled by an the personal computer. The rapid growth addressable product; that is, it must be of that market and the prolification of possible to reconfigure the service in RGB monitors, means that better teletext the customers horne via remote signaling service will be possible on cable with from the cable headend. A valuable leased equipment. Teletext modules service with a large number of options leased by cable companies will likely invites the subscriber to change his have both RF and RGB outputs. The sub­ mind and try different flavors. scriber with an RGB monitor will be able Eventually, the subscriber tailors the to enjoy higher quality displays without service to his specific needs. In the the need of buying a new television set meanwhile, considerable changes in the which has the teletext decoder built service configuration are required. With in. The limitations on the antenna an addressable product, this represents terminal connected display are funda­ only a modest operational burden. That mental to the NTSC color television burden is justified once the subscriber system. Improvements in future color finds the services that suit his television receivers will not result in needs. Without addressability, there is significantly better teletext displays, a need to visit the subscriber's horne as long as the connection is through the each time he wishes to change the antenna terminals. ~7 One-Way vs. Two-Way the cable company can send marketing messages to all subscribers of a given Nearly all cable systems in the category. Likewise electronic news­ United States are one-way. A small letters for specific groups of fraction of cable systems are capable of individuals can be transmitted. being converted to two-way and an even smaller fraction, less than one percent, Some Fundamentals are operational two-way systems. Fortunately, one-way teletext has a With all the enthusiasm over tremendous potential for providing a videotex, it is well to go back to useful and interesting service. This is fundamentals from time to time to re­ particularly true of full field teletext establish a sense of reality. Any where the numbers of pages are sub­ videotex service will require (a) an stantial. A bridge between one-way and interesting information base, (b) an two-way and a significant enhancement to information provider (c) a manufacturer teletext is telesoftware. With tele­ or origination and transmission software computer programs are down equipment, (d) a one-way or two-way loaded into resident personal transmission medium, (e) a manufacturer computers. The subscriber then of receiving equipment, (f) sales (or interacts with the computer program. A leasing) and service organizations for one-way system has thus been given the receiving equipment, (g) willing interactive capability. Of course, what buyers (or lessors) of the receiving is still missing is transactional equipment who are also interested in and capability1 that is, the potential for willing and able to pay for the placing orders and sending information information, (h) vast pools of capital back to the cable headend.