ALTERNATIVES IN CABLE

Walter s. Ciciora William L. Thomas

AMERICAN & COMMUNICATIONS CORPORATION ZENITH RADIO CORPORATION

Introduction without increasing bandwidth. VBI 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 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 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. Temporarily, held by knowledgeable and willing much of that need could be served by investors who are capable of evaluating touch tone telephone key pads. As the risks and potential rewards of this impulse pay-per-view becomes practial enterprise, (i) a business plan which from a technical standpoint, (and an convincingly demonstrates that it will economic standpoint), the same ten-key work (not just technically), and (j) pad used for impulse pay-per-view can leadership to make it happen. service the need to communicate numerical data to the headend. Thus, a While this list seems detailed, it two-way system can be assembled from a is in actuality cursory. For example, fundamentally one-way teletext service item (e) the receiving equipment manu­ and the hardware required for impulse facturer, is highly dependent on a pay-per-view. This will be an manufacturer of Integrated Circuits evolutionary process where the hardware (IC's). These plastic encapsulated, develops overtime and bridges are built quarter-inch-on-a-side wafers of highly between systems motivated by entirely processed silicon make it possible to do different needs. the eletronic magic which puts the "video" into "videotex." These IC's Plain vs. Fancy contain tens of thousands of transistors each. Depending on which videotex The telephone industry has an system is under consideration, the expression for its basic service - POTS, number of these IC's can vary from three which stands for Plain Old Telephone or four to dozens. Clearly, it takes Service. We can borrow that term and many person years to design circuits apply it to teletext. The issue then is involving tens of thousands of tran­ Plain Old Teletext vs. Fancy. Very sistors. The usual Alice-In-Wonderland little imagination is required to fancy assumption is that it will just happen. up the teletext system and obtain truly This is due to the phenomena of Digital attractive results. An example of such Mania. The mind infected with this interesting features is found in the malady believes that anything can be Zenith full field tiered addressable done digitally and in three years it system. Each decoder is capable of will be free. Furthermore, believing responding to a specific page number will make it so. Digital watches and that all other decoders ignore. This calculators are the usual "proof" permits the implementation of an elec­ offered for these beliefs. tronic mail system. Messages can be sent to an individual decoder carrying Entrepreneurial Factors subscribers specific information. Examples of information which serve the The entrepreneurial factors, (h), cable company's needs are billing status (i), and (j) are the most commonly reports and messages about new services. neglected in any analysis of videotex In addition to individually addressed scenarios. Yet, they influence every pages, group pages are possible. Thus, step along the way. The most important missing element is the confidence that directive antenna with VHF when compared the end user will perceive a value which to UHF reception. This lack of direc­ is commensurate with his costs. The tivity is most harmful in high multipath uncertainty in the estimates of these situations, such as large cities. The costs is a serious problem contributing average quality of antenna installation to a lack of confidence. The cost is lower in the u.s. This is due to the components include receiving equipment relatively low cost of television price or lease costs, media usage fees, receivers. An installed quality UHF/VHF and information prices. The value side antenna and downlead could easily exceed of the equation, that is, the benefit or half the cost of the color receiver. In utility offered by videotex is even Europe, where receivers have been harder to measure or estimate. The relatively more expensive the cost of a components of utility are the quality UHF antenna installation is a entertainment, the cost savings, and the modest percentage of the receiver price opportunities created by the information and a prudent investment at that. brought via videotex. Until the entrepreneurs are confident that this The most difficult signal parameter cost:perceived value equation is impairment to deal with is multipath or balanced, they will not proceed. They ghosting. Weak signals are relatively won't create the scenarios and exercise easily handled by the digital nature of the leadership which will tap the pools teletext. The second most serious of capital so necessary to provide the threat is impulse noise. U.S. standards required investments. Certainly, the for motor brush noise and ignition noise high cost of money (interest rates) adds are much less stringent than in Europe. to the risk. And motors and gas engines are in countless electric home and garden appliances. Anyone with a teenage Broadcast Teletext daughter who has a hair dryer can well appreciate this. World-wide, the most successful videotex service at the present time is Experience has shown that even the broadcast teletext. Specifically, the inherently more rugged defined format mullard chip set is employed in about teletext system used in most European two million teletext receivers. One teletext receivers experiences diffi­ could naturally assume that this means culty in the broadcast environment of that broadcast teletext will be most the u.s. This situation would be even likely to lead the videotex race in more difficult using the variable format U.S.A. There are several major schemes also proposed in the u.s. differences between the u.s. and the Proposals have been made for error European experience which may invalidate detection methods to patch over these this assumption. deficiencies. However, these proposals require the addition of more overhead Firstly, the signal environment in data bits which further reduce the the u.s. is much less hospitable than in information carrying capacity of an Europe. Rather than two or three already limited system. programs with a thousand repeaters, there are a thousand stations with The visibility of retrace lines on almost no repeaters. This translates color TV receiver models in current into a situation in the u.s. where production, limit the number of Vertical nearly everyone receives several low Blanking Interval (VBI) lines available quality signals and maybe one or in the broadcast teletext service to a possibly two quality signals. This is precious few. The consequence of this instead of the European situation where is a no-win choice between limited almost everyone is in a quality signal information presented with modest environment. The signal quality impair­ waiting times and adequate amounts of ments include low signal levels, co­ information with mind numbing delays. channel and strong adjacent channel High resolution graphics techniques such interference, multipath (or ghosting) as Picture Descriptor Instructions distortion and a wide range of trans­ (PDI's) aggravate the situation by in­ mitter and broadcast antenna quality and creasing the transmission time per page condition. Receiving antenna problems while increasing the vulnerability to still further complicate the issue. error. This was well demonstrated in Since much of the u.s. programming takes the Washington D.C. trials over station place on VHF, antennas must be much WETA. Error protection adds cost and larger for the same amount of direc­ transmission delay. It further presents tivity. Conversely, the same number of an unhappy choice: a) wait until all "pounds of iron" will yield a less data has been correctly received before

169 creating a picture, or b) paint the Switched Network (PSN} is rapidly going picture in steps with interspersed to Universal Measured Service (UMS}. delays until it is complete. The waits There is good reason to fear that the in a noisy or distorted signal environ­ usage cost will absorb most of the ment can be severe. A note here about available disposable consumer income. "microprocessor-based" systems is in This will leave little if anything for order. Since microprocessors have the receiving equipment lease fee, the limited speed, the data must be sent in information purchase, and the share of bursts so they can be digested before the originating equipment. Information display. Since POI's must be sequen­ providers believe they're going to get tially painted on the screen (i.e., the usual cable TV revenue split, the loaded into the bit plane memory} a cost of telephone interactive videotex missed segment causes a delay for a full will be prohibitive. Another difficulty transmission cycle until the missed is in the nature of the PSN itself. The segment can be correctly executed. The architecture of the PSN is statistically alternative is complete buffering of the designed based on certain assumptions as data. to number of calls and length of calls, i.e., hold times. The hold time The above discussion implies that statistics are likely to be signifi­ the broadcast teletext service in the cantly upset by interactive videotex. u.s. must be inherently limited -- much The success of interactive telephone more limited if extensive high resolu­ videotex may be self-limiting by the tion graphics are employed. The cost problems it can cause on the PSN. situation further unbalances the Longer times until dial tone, more "cost:perceived value equation". Even frequent busy signals, and less avail­ if the teletext decoder were free, the ability of the phone for its conven­ added cost of a quality antenna instal­ tional use are just some of the lation itself may exceed the perceived ramifications. value of such a limited service. And, of course, the teletext decoder is not Another serious concern with two-way free. Depending on the system chosen, videotex is that the cost of computer the decoder can be very expensive facilities on a per user basis may be a indeed. substantial percentage of the total cost. In sharp contrast to broadcast If this wasn't enough, the standards teletext where origination hardware cost issue is yet one more problem. The is the same for one user as millions, usual u.s. standards setting mechanism subscriber growth for telephone has failed. Customarily, the Electronic interactive videotex necessitates Industries Association (EIA} proposes a origination computer growth. standard to the Federal Communications Commission (FCC} which studies, modifies The two principal advantages of two­ and approves it as the law of the land. way interactive telephone-based videotex This failure is probably because the as compared to broadcast teletext are: standard questions involved are too a} access to a much larger data base, complex for committee decision. In and b) transactional services, such as fact, most of the controversy in th EIA shopping, banking, and electronic Teletext Committee has been over issues mail. As will be discussed below, a of marketplace desire. What are the much more cost effective means of trans­ relative tradeoffs between graphics porting larger volumes of information is resolution, cost and waiting time? It one-way, full field cable television. may be wiser in issues as complex as The second advantage listed above brings this to let the marketplace choose serious concerns about security, between several choices than to pick privacy, and the interface to other between just two choices: a} the computers. committee's guess, and b) rejection of the whole idea. In either case, it will One way Cable Teletext be a marketplace decision. In the first case the market has multiple choices, in Probably the most promising videotex the latter, just two: "yes" or "no". technology in the u.s.A. today is one­ way cable TV teletext. The reasons are: Telephone Interactive Videotex a} no multipath or ghost problems, The principal inhibiting factor with telephone-based, two-way interactive b) significantly better overall videotex is that the medium over which signal quality, the message itself travels has a usage cost associated with it. To use the c) spectrum availability for full­ telephone terminology, the Public field use,

170 d) the ability to limit access and financial, entertainment, etc. He can thus charge for the service, select and pay for only the services he desires. The addressable nature of the e) the ability to segment the product allows control of reception from market through tiered address­ the headend. Thus, even if the able services, subscriber frequently changes his mind, his receiving equipment can be f) one-way electronic mail with reconfigured to match his changing firm security thru tastes. addressability, The cable subscriber is already g) a preselected market of video­ accustomed to monthly bills for service oriented potential customers, and equipment leasing. The teletext service is thus incremental. It does h) a market already accustomed to not require the subscriber to adopt a receiving equipment leasing, new way of thinking about the service.

i) the relative unimportance of An interesting by-product of standards, addressability is being able to send individual pages to each subscriber. j) the future upgradeability to This is possible even though the cable two-way interactive services, system is not a switched network. Electronic mail distribution is thus k) the present ability to do a possible in even a one-way system. The hybrid two-way thru telephone first application is subscriber "ten-key" requests. notification of billing and account status. This can be extended to include More than half of television house­ "telegram" like service where the holds are passed by Cable TV in the messages are phoned into the cable U.S.A. More than half of these company and then sent to the individual subscribe. Thus, about 30% or 28 teletext receivers. million subscribers now have cable. And the growth rate is aggressive. Since each cable system is a universe unto itself, the need for The new modern cable systems provide national standards is obviated. The excellent signal quality on from thirty­ digital nature of videotex facilitates five to sixty channels. Currently, 440 translation of information between MHz dual cable systems are being in­ various protocols. stalled in major markets providing a total of 120 television channels. Both The one-way cable system can begin signal quality and spectrum availability to have some two-way capability through disappear as issues in these cases. the use of the touch tone telephone Thus, not only are the 120 VBI's at the keypad and appropriate computer cable operator's disposal, but he can interfacing at the cable headend. Thus, partition them according to his needs. an even larger data base can be In the broadcast arena this is not available with two kinds of pages: a) possible because of the difficulty of those that normally reside on the orchestrating the level of co-operation teletext repeating cycle, and b) those between the various owners of the VBI's that get requested individually. A in a given market and the anti-trust statistical tabulation can be used to legal questions. decide when to convert type "b" pages to type "a" pages and vice versa.

The most exciting cable opportunity Two-Way Interactive Videotex and Cable is a full field, tiered addressable service. Rather than just four to eight In addition to cable's advantages lines in the VBI, over 500 are listed above, cable has the promise of available. This yields a page rate of two-way. This promise is realized in over 500 per second. This can be less than 1% of u.s. cable systems at combined with cable's addressing present. Significant technical, opera­ techniques so that each box can be tional, and economic difficulties controlled from the cable headend. remain. However, true two-way is a Furthermore, the service can be promise broadcast can't even contem­ partitioned into separate services each plate. of which can have individual subscriptions. Thus, the subscriber can Cable's two-way is not a switched choose between various teletext system as is the telephone network. magazines covering general news, sports, However, electronic message switching

171 schemes accomplish the same result at present reality. It now exists only as much less hardware cost at the expense either a very limited non-videotex­ of bandwidth. But bandwidth is cable's compatible service or as a field trial. principle available resource. Because of the bandwidth, usage sensitive pricing will not be necessary for the Conclusion foreseeable future. The creator of a videotex system for The telephone disadvantages with cable has many alternatives to choose regard to origination computers apply to from. This makes the task interesting. cable as well with one important Several examples of cable videotex difference. Since cable videotex will systems exist now and the cable have an integral one-way teletext community should study the differences. service, the quantity of two-way pages Cable videotex is imminent and the time can be significantly less. These would to learn about the choices is now. be limited to only the less popular pages. The tens of thousands of more The good news this paper tries to popular pages would be delivered via convey to its audience is that videotex one-way. is most naturally a cable service. Cable has a number of significant It is important to keep a realistic advantages over rival media such as view of cable two-way. It is not a broadcast and telephone.

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