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.RCP Engineer Vol. 28No. 5 Sept./Oct.. 1983 -

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TONY: Sunny DIGITAL skies allday very hot. BROADCAST HIGH: 95 LOW: ?2 HUMIDITY: 75% NBC & NABTS AIR QUALITY: Good PRESENT TOMORROW. More TELETEXT sunshine and continued hiqh temperatures. Front cover graphics produced by Laurence Merritt and James Kimac (Art director: Annette Geyer) of NBC Teletext maEngineer A technical journal published by RCA Technical Excellence Center 13 Roszel Road P.O. Box 43:, Princeton, NJ 08540 TACNET: 226-3090 (609-734-3090)

RCA Engineer Staff

Tom King Editor Mike Sweeny Associate Editor Louise Carr Art Editor Frank Strobl Contributing Editor Betty Gutchigian Composition Phyllis Grimm Secretary

Editorial Advisory Board

Jay Brandinger Division Vice -President and General Manager, "SelectaVision" VideoDisc Operations John Christopher Vice -President, Technical Operations, RCA Americom Jim Feller Division Vice -President, Engineering, Government Systems Division Mahlon Fisher Division Vice -President, Engineering, Video Component & Display Division Hans Jenny Manager, Engineering Information NBC Teletext, based on exciting new digital broadcast technology, promises to be an entirely new Arch Luther Division Vice -President, Engineering medium for the exchange of information. Some and Product Assurance, Commercial Communications have called it an "electronic magazine," but it could Systems Division eventually offer much more. Graphics are one of the main concerns of teletext producers, and Howie Rosenthal Staff Vice -President, Engineering NBC-as our cover shows-is no exception. The Joe Steoger Division Vice -President, Engineering, front cover images were made at NBC with equip- RCA Service Company ment and software from Videographic Systems of Bill Underwood Director, Technical America. Thanks to Barbara Watson at NBC Tele- Excellence Center text, New York, we can show them to you. Bill Webster Vice -President, Laboratories NBC transmits teletext "pages," over -the -air, in the vertical blanking interval of the standard TV Consulting Editors picture. Today, few people own the decoders needed to see the images we've reproduced, but Ed Burke Administrator, Marketing they are in development. The system operates Information and Communications, according to the North American Broadcast Tele- Government Systems Division text Standard (NABTS) currently being refined by Walt Dennen Manager, Naval Systems Department standards -setters at RCA Laboratories and else- Communications and Information, where (see the article on page 15 by Brian Astle). Missile and Surface Radar NABTS partisans point to two key advantages of Charlie Foster Manager, Systems and Procedures, the variable coding that their system uses- RCA Laboratories superior graphics, and software compatibility with John Phillips Manager, Business Development videotex systems (videotex essentially operates as and Planning, RCA Service Company a two-way teletext transmitted over telephone and cable -TV lines). NABTS alpha -geometric graphics give reliable color and identifiable reproduction of company logos-a must for attracting advertiser To disseminate to RCA engineers technical information of professional value To publish support. in an appropriate manner important technical developments at RCA, and the role of the -MRS engineer To serve as a medium of interchange of technical information between various groups at RCA To create a community of engineering interest within the company by stressing the interrelated nature of all technical contributions To help publicize engineering achievements in a manner that will promote the interests and reputation of RCA in the engineering field To provide a convenient means by which the RCA engineer may review his professional work before associates and engineering management To announce outstanding and unusual achievements of RCA engineers in a manner most likely to enhance their prestige and professional status The changing environment for technical standards

Imagine moving into your newly con- Whereas U.S. television standards structed home and finding that your organizations are desperately trying electrical subcontractor has installed to head off a total collapse, the inter- the latest in improved technology for national environment for standards in the wiring, connectors, and control some ways has been greatly circuits. Very good so far, but sup- improved in recent years. The inter- pose also that the voltage and fre- national arena (especially in televi- quency are different from those of sion) has long been dominated by K.H. Powers your appliances and none of the old nationalistic pride and political con- plugs will fit the new sockets. siderations. The international stan- This extreme case illustrates mis- dards bodies such as the CCIR have placed marketplace standards, and had to be content with documenta- one finds it difficult to imagine that tion of existing national standards as any responsible industry could permit a thwart to the proliferation of un- such a chaotic situation by not set- necessary new ones. The historic ting specifications for compatibility event that occurred in 1982, when the across system interfaces. Yet, the CCIR Plenary Assembly adopted broadcast industry is facing just such unanimously a single specification a dilemma today in the wake of for the signal interface in the all -digi- landmark Federal Communications tal television studio, constituted a Commission (FCC) decisions on ste- new high in international technical reo AM, teletext, and, imminently, cooperation. multi -channel television sound. The euphoria of this unprece- Many de facto standards serving dented success will linger as groups us well today arose because a com- of nations are now busily reaching petitive shake -out in the market left a agreements rather than hotly debat- few products that, at the time of their ing such new possible standards as introduction, either stood alone or did analog component interfaces and not require interfacing with other sys- extended -definition television for new tems. The 3/4 -inch U-Matic videotape transmission systems such as the cassette is a good example. In the Direct Broadcast Satellite. absence of a shake -out, the market- RCA engineers have historically place fails, leading to multiple stan- contributed to television standards dards that are often detrimental to all development and are continuing to concerned, particularly when one do so in the interests of RCA and the standard has little to offer over television industry. Although this another. issue of the RCA Engineer highlights In response to the FCC's moves the applications of digital technology toward deregulation, the television in television, the thread of standardi- industry is forming the new zation issues permeates much of the Advanced Television Systems Com- work reported. mittee. The Committee will coordinate the development of voluntary U.S. national standards for the generation, distribution and reception of improved -quality television signals made possible through emerging new technologies. The intention of the Committee is to anticipate the Kerns H. Powers technology and to set specifications Staff Vice -President, for interfaces before new products Communications Research create incompatibilities. RCA Laboratories alMaiEngineer Vo . 28 I No. 5 Sept.Oct. 1983

history 4 RCA Automated Systems: Twenty-five years on America's Technology Highway A.J. Skavicus

standards setting 10 The development of international television standards R.N. Hurst 1K.H. Powers

15 Teletext standards in North America B. Astle

digital 26 Technology for digital television broadcast topics F.J. Marlowe

30 Component analog video recording for studio applications T.M. Gurley 1C.J. Haslett

38 Digital videotape recorders: Tape format and error -concealment considerations G.A. Reitmeier

44 Wideband picture detail restoration in a digital NTSC comb -filter system A. Acampora

48 Some power considerations for consumer -type high -definition -television displays W.E. Babcock 1W.E. RoddalW.F. Wedam

general interest 57 Post -molding processing is a unique requirement for VideoDisc D.F. Hakala

departments Patents, 601 Pen and Podium, 621 News and Highlights, 65

128 Skavicus: "We have over 100 military contracts and will continue to AMERICAS TECHNOLOGY expand our leadership role in all our systems areas." HIGHWAY

Hurst/Powers: "The document produced by the CCIR (Comit4 Con- 10 sultatif International des Radio Communications) . . . took a great step 13i MKT. toward the establishment of a true international television exchange (COMMON SAMPJNIG RATE) medium." Astle: "I believe that the ability to choose timely and attractively pres- 15 ented information without apparent cost will make teletext a popular NBC ',TELETEXT service . . . ."

gle 26 Marlowe: "RCA engineers will not merely witness the change from analog to digital TV-we will create much of it."

Gurley/Haslett: "Recently, the concept of a component analog stu- 38 dio, centered on a component analog VTR, has received much attention . . ." Reitmeier: "The appropriate use of tape format to distribute dropout errors in the television raster allows the use of two-dimensional signal processing to conceal errors."

SHIFT Acampora: "The digital filters presented in this article have wider REGISTER bandwidths than the analog filters currently used to extract vertical detail in pictures." 44

Babcock/Rodda/Wedam: ". . operation of the horizontal scan- 48 ning system at double the normal scan rate presents major problems due to stresses imposed on the horizontal output transistor and damper."

Hakala: "An improved understanding of disc -surface physics and chemistry, and their relation to formulation and molding process conditions, will result in a more efficient surface treatment and lubrication."

in future issues... software, manufacturing, automating the engineer's workplace technical excellence Automated Systems

410

Twenty-five Years on America's Technology Highway

By A.J. Skavicus

Forover a quarter of a century, Automated Systems (AS) Our early involvement in certain technologies, which has been in the forefront of America's high-technology only today are catching the public's attention, is depicted revolution. Route 128 (a beltway surrounding Boston, in the technology chart shown to the right. This chart- Massachusetts), was recently dedicated as America's Tech- presented in five-year incrementsdepicts some of the nology Highway because this area is recognized as the major technical advances, starting with the early space birthplace of high technology. programs and leading -to our current business areas. Like "Silicon Valley," the term "Electronics Row" is Inertial guidance systems, one of the advanced tech- often used to describe the hundreds of companies involved nologies of the fifties, was also one of the first projects at in high-tech work in our area. Automated Systems, geo- AS. To support this growing technology, a unique analog graphically located in the heart of "Electronics Row," computer was acquired. Archaic by present standards, it started and continues to be in the fast lane of America's was sophisticated for that era. The combination of knowl- Technology Highway. High -quality, low-cost manufactur- edgeable personnel and well-equipped facilities enabled us ing capabilities have allowed our engineers and scientists to to bid and win the SAINT System program (Satellite create superior systems and products. These have become Inspector). The successful effort on this program provided our trademark in military circles. The axiom that "success the basis for our early entry and long history of supporting breeds success" applies to Automated Systems. But, our subsequent space programs. success was no accident. During our first five years in Burlington, many other Careful corporate planning went into the formation advanced technologies were investigated and applied to of Automated Systems. Engineers were added in direct military programs. Extensive effort was applied to electro- response to program needs, and they were selected based optics, lasers for ranging applications, miniature computer on their outstanding technical ability. The Burlington plant developments, as well as unique mechanical design tech- was constructed in 1958, and a complement of 450 techniques using weldplate design. At RCA, lasers and mini- nical and support people were moved into the new facility. computers were not a product of the seventies, but of the This move marked the beginning of our first 25 years. fifties!

4 Technology Trend Chart

EARLY SPACE AUTOMATIC TEST C3I VEHICLE TEST PROGRAMS SYSTEMS " SYSTEMS SYSTEMS 1 Interial Guidance System 1 Multi Purpose 9 HELLFIRE 1 Infrared, LASERS, Mini- 8 DFAS 1 BITE 2 SAINT Test Equipment computer, Electro-optics 10 AH-64 9 EIFEL 2 ATSJEA 3 LEM (ATCA, DECA) 2 DIMATE Study Contracts 11 RPV 10 As 3 STE/ICE 4 Rendezvous Radar 3 APTE 2 ADA 12 NARF 11 Project E 4 STE-M1/FVS 4 LCSS 3 AN/TSW-7 13 AN/GSM-285 12 USAFE Terminal 5 STE-X 5 AMACS 4 TIPI 14 PLSS 13 LASER TRANS Modules 6 VMS 6 AEGIS/ORTS 5 AN/GVS-5 15 ATSS 14 Expendable Decoy 7 SPADE 7 EQUATE 6 REMBASS 15 Schottky Barrier Camera 8 Vetronics 8 USM/410 7 TCAC

EARLY SPACE AUTOMATIC TEST VEHICLE TEST PROGRAMS SYSTEMS C3I SYSTEMS 58 SYSTEMS ®

1 63

2 0 0 1 3 4 68 00 3 5 n. A

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1 4 6 9 @OD 10 11 12 8 At./INA/1 0)(7)(T) 13 14 15 1983 ,LAAZ\A r 128 AMERICA'S TECHNOLOGY HIGHWAY for the U.S. Signal Corps resulted in the development and production of Depot Installed Multi -Purpose Automated Test Equipment (DIMATE) in the Tobyhanna Depot, Pennsylvania. This equipment performed in an exemplary fashion. It established AS as the recognized leader in automatic test equipment. Additional study contracts were completed, solidifying our position with the Missile Command of the U.S. Army, Huntsville, Alabama. The technology developed by AS for the Army was also used, through technology transfer programs, in the development of equipment for the RCA Picture Tube Division. The Auto- matic Programmed Test Equipment (APTE) was developed to automatically test color kinescope tubes. A series of tests were programmed to evaluate these tubes on a "go, no-go" basis. The equipment was subsequently installed in the Marion, Indiana picture -tube plant. In 1968, the engineering team responsible for this project received the David Sarnoff Award for Outstanding Technical Achievement.

Automated Systems -1958. Seventies As AS entered the seventies, it was still in the fast lane on Amer- ica's Technology Highway. Automatic Test Equipment (ATE) was emerging as a very important product line. MICOMhad contracted for the Land Combat Support System (LCSS), and 48 systems were fielded. Again, the techniques developed for military applications were applied successfully to commercial ventures.Equipment was designed, developed, and built by AS for WaltDisney World, Florida. Overseeing the facilities, utilities, fire protection, security, is an integrated network of computers. These computers, interconnected in a multi -threaded manner, form the nucleus of an Automatic Monitoring andCon- trol System (AM&CS) that keeps its fingers on the pulse of the entire Walt Disney World complex. The system was designed such that failure of critical elements results in a gracefully degraded mode of operation without loss of critical information. Also during the 1968-1972 years, AS became heavily involved in airborne programs, the precursors of our Command, Control, Communications/Intelligence (OD business. The Post Attack Command and Control System-Airborne Data Auto- Automated Systems -1983 (Inset: Avionics Test Facility). mation (PACCS-ADA) was an automated system for the SAC Airborne Command Post facility that demonstrated the feasibil- ity of automating functions presently performed by the airborne Sixties battle staff. The system was built around an RCA -developed From 1963 to 1968, on America's Technology Highway, AS Variable Instruction Computer (VIC). The most significant sys- created and expanded new technologies used in such systems as tem -integration problems were in the selection of existing data- automatic test equipment, infrared fiber optics, electro-optical processing technology suitable for use in the airborne environ- signal processing, advanced airborne radar, and space systems. ment and the integration of PACCS-ADA into an existing AS was awarded contracts on the Lunar Excursion Module aircraft. In the latter case, the system required compatibility with (LEM). For that work, the David Sarnoff Award for Outstand- radiofrequency equipment operating over a 15 -kHz to 10-GHz ing Technical Achievement was received in 1970. The LEM frequency spectrum. AS, now moving at top speed, won one of contracts helped us secure an honored position in the space pro- the Tactical Information Processing and Interpretation (TIPI) gram. With the development and production of the Rendezvous contracts. Radar, the ATCA (Attitude and Translation Control Assembly), The TIPI System, still operational, is a land -based system and DECA (Descent Engine Control Assembly), we pulled into that is transported by mobilizer, truck, helicopter, aircraft or the passing lane. All 13 LEMs were outfitted with equipment ship. The system is designed to increase the capability, improve that was designed, developed, and produced by AS. the timeliness, and increase the accuracy of intelligence informa- During this time, AS also began developing one of its cur- tion by automating certain combat intelligence tasks. The Dis- rent major product lines-Automatic Test Systems. The initial play Control/Storage and Retrieval (DC/SR) segment of TIPI contract for Multi -Purpose Test Equipment (MTE) was started consists of shelter -mounted equipment, computer software, intel- in 1962 and completed in 1964. Follow-on work in this area ligence data, and facilities. This segment, designed for use by the

6 RCA Engineer 28-5 Sept./Oct. 1983 USMC and the USAF, interfaces with other segments of the maximum specified load conditions. In the test system, the dig- TIPI System and other existing field systems. ital stimulus/buffer was used to drive a Unit Under Test (UUT) The Air Traffic Control Central (AN/TSW-7,7A), devel- with signals whose high and low voltage levels were program- oped in the early 1970s under contracts with the U.S. Air Force mable over a range of -20 V to +20 V. The pulse width and and the U.S. Army, is a transportable, self-contained system that pulse -repetition rate were controllable from programmable provides the communication facilities and meteorological data switching signals. needed to control aircraft at or within the terminal area of a landing site. It can be deployed at an unprepared site to support Eighties tactical operations, and then be redeployed within a matter of hours. It can also be used at large bare -base tactical airfields. To The eighties have brought rapid growth in our three major prod- date, 45 production -models and 4 development -models have uct lines-Automatic Test Systems, Vehicle Test Systems and been produced at AS. C3I Systems. The competition for military business has heated From 1973 to 1978, AS added its skill in automatic test up and technology continues to push forward at an accelerating technology to the AEGIS program by joining the RCA rate. Moorestown team. The data acquisition, control and display for Some specific advanced technology areas of interest to AS the Navy's Operational Readiness Test System (ORTS) provides in the eighties are high -density fail-safe microprocessors; bubble on-line, real-time monitoring of the status of the AEGIS Naval memories; user-friendly display and control devices; fiber -optics Weapon System. It was designed to determine operational read- data buses; survivable external communications; ultra -rapid iness at system and equipment levels, to evaluate performance communications switching and reconstruction techniques; sys- degradation and recommend reconfiguration, and to provide tem -security methods; staring infrared imaging devices; image - centralization of maintenance functions for display and control pattern recognition; trackers; lighter -weight structures; extremely that can be operated with minimal personnel training. Specific effective environmental protection techniques; and, most impor- goals to be achieved were fault -detection coverage of 90 to 95 tant of all, efficient software, including new developments such percent with a false -alarm probability not greater than one as common English languages and artificial intelligence percent. techniques. The application of minicomputers started in 1968 when AS Our challenge in the eighties is to keep our ongoing prod- used a minicomputer for the APTE program. In 1974, the Wells ucts current and to evolve new products using the diverse Fargo building -management system was designed using many of advanced technologies to satisfy customer needs. In the follow- the devices developed for APTE. The Wells Fargo system man- ing paragraphs, the current status of our three major product ages a major San Francisco skyscraper, two other local buildings groups is discussed, along with some of the technical challenges and a building located forty miles away. In addition to providing we face in each group. security that set a new standard for the banking industry, the system optimized the mechanical systems operation in the conserva- Automatic Test Systems tion of energy. The minicomputers were configured with Our major Automatic Test System product, the AN/USM-410, redundant peripherals to preclude interruption of system opera- is in peak production with 132 systems ordered and 71 tion. The printed circuit boards required by this system used the delivered. Computer Automated Design System (Applicon) that was The AN/USM-410 is the Army's standard ATE for inter- installed at AS in 1972 and augmented in subsequent years. This mediate and depot levels. It is deployed worldwide in support of technology represented the early use of CAD/CAM and again every major Army combat and combat -support system. For kept us in the heavy traffic now found in the passing lane of the example, it supports the Abrams MI battle tank, the AH-64A highway. attack helicopter, the Sgt. York air defense gun, the Firefinder (a In the mid -seventies, Automated Systems became very mortar -locating radar), and tactical field radios. Many of these active in the development of simplified test equipment for inter- systems are only now being introduced to the field, and they will nal combustion engines (STE/ICE). However, simplicity of be part of the Army's arsenal into the 21st century. RCA and operation meant sophisticated hardware and software based on the Army will make the current AN/USM-410 a platform for ingenious testing techniques. AS developed the concepts and technology insertion by assuring test capability and ATE main- rationale behind these techniques: performance testing while at tainability with the systems it supports. engine idle speed, power testing, ignition -system analysis and In parallel with the AN/USM-410 production, work is starter -current waveform analysis. proceeding on a new -generation system to match future custo- The mid -seventies also marked the introduction of hybrid mer needs in Test Program Sets, hardware architecture, and technology at AS. Size, weight, performance, and volume are software. traditional hybrid -microcircuit driving requirements. Each of Improvement in Test Program Set (TPS) generation is these factors was important in developing circuits for the third- necessary. Test Program Sets are the software and interconnect- generation ATE, later to be called the AN/USM-410. ing devices that make it possible for a computer -controlled The introduction of hybrid technology represented a major automatic test system to evaluate and diagnose the condition of advancement in our manufacturing capability. This technology Units Under Test. Early TPS development, even for 1960s tech- put us ahead of the competition. Typical of our hybrid technol- nology, was engineering -manpower intensive, costly, and time- ogy was the digital stimulus buffer hybrid, made up of 10 beam - consuming. Currently, test -set designs are written in the high- lead diodes, 12 beam -lead transistors, 2 chip capacitors, and 18 level, English -like ATLAS language. Compilers perform thick -film resistors. The package had leads for edge -type connec- vocabulary and syntactical analysis of ATLAS programs, help- tion of a printed circuit board. The conformally-coated circuit ing the designer debug his program before trying it on the ATE. provided a heat sink to permit power dissipation of 2 W under To assist the engineer, an automated test library has been devel-

Skavicus: Twenty-five Years on America's Technology Highway 7 oped. Additionally, a family of automatic test generatorsis avail- Vehicle Test Systems able for testing complex, high -density digitalcircuits. To date, almost 7,000 Simplified Test Equipments(STE) have There is a strong demand for more -flexible automatic test been ordered. The concept of simplified test equipmentevolved system architectures. Users must have theability to meet chang- from a military requirement to solve complex diagnosticprob- ing requirements and support new technologies. This user lems as close to the front line as possible. The complexityof new demand is driving automatic -test -system design towardmodular, and emerging equipment and their associated technicalmanuals, reconfigurable architectures. coupled with the complex diagnostics they required, weremajor The reconfigurable architectures are being implemented problems. AS has developed four test sets: STE/ICE (STEfor through the use of distributed microprocessor networks. Each Internal Combustion Engines), STE-M1 (STE for the M1 function contains a processor that controls its operationand data Abrams Tank), STE-M 1 /FVS (STE for the M1 AbramsTank processing, with a central processor coordinating the system and M2/M3 Bradley Fighting Vehicle Systems), andSTE-X operation. Interconnecting the system through a bus network (STE that is expandable to new and existing combatvehicle sys- permits functions to be added, deleted, or relocatedwithout dis- tems and engines). STE-MI /FVS tests thewhole vehicle, that is, turbing system operation. all of its mechanical and electronic subsystems. In 1980the The software to control such a system is based on a mod- David Sarnoff Award for Outstanding Technical Achievement em, modularly structured operating system.Application software was presented to the AS team forwork on STE/ICE in recogni- is written in the latest version of ATLAS and compiled on a tion of this fact. As pioneers of this state-of-the-arttechnology, newly developed syntax -driver compiler. ADA is used asthe we have earned a worldwide reputationfor leadership in Vehicle program -design language for all of thesoftware being developed. Test Systems. In addition to the development of a new generation of Using the vehicle experience gained from our STE pro- automatic test system products, work has also started on the evo- grams, we have begun the evolutionof significant concepts in lution of Automated Systems Total Integrated LogisticsSupport the field of VETRONICS (Vehicle Electronics). The concepts that will use most of the advancedtechnologies pre- VETRONICS concepts involve the requirements for integrated viously discussed. operation of vehicles, with minimal or no crews, in a variety of missions. Conceivably, VETRONICS will involve every advanced technology area discussed earlier. C3/Systems Albert J. Skavicus graduated Summa Cum Laude from the Catholic University Our C3I Systems involve diverse products, suchas sophisticated of America, Washington, D.C., in 1943 surveillance and target -acquisition sensors, communications, dis- where he received a BSEE degree. tributed data-processing subsystems, and effectiveman -machine After Navy service, he joined RCA as an interface subsystems. Three of our current C3I Systemsprograms engineering trainee in 1946. He was are TCAC, REMBASS and AN/GVS-5. promoted to Design Leader in 1952 and Design Manager in 1955. From 1955 to Our largest C3I program is the Technical Control and 1969 Mr. Skavicus had management Analysis Center (TCAC) (AN/TSQ-130V). The system satisfies responsibility on numerous ATE pro- the primary mission of providing Army division andcorps grams. Currently, Mr. Skavicus is Man- commanders with Signals Intelligence processing/reporting and ager of Engineering Services at Auto- mated Systems. electronic warfare management support. A three -shelter configu- Contact him at ration can be deployed to support the Tactical Operations Cen- Automated Systems . ter (TOC). The shelter hardware, software, and communications Burlington, Mass. architectures necessary to fulfill the TCAC mission also provide TACNET: 326-3083 a flexibility that allows a single shelter or a group of shelters to multiple repeaters can be deployed to extend the satisfy the military requirements either for a mobile communica- range. The REMBASS program has completed its development phase and tions or analysis facility. Major components of each shelter are is about to go into limited production. the following: a Militarized Super Minicomputer, three dual - The AN/GVS-5 is a hand-held laser rangefinder that screen operator workstations, a line printer, radios, crypto gear, a was developed for the Army by AS. It is a lightweight (2.3 kg), magnetic tape unit, and a disk drive. This configuration provides inexpensive device that determines the range to considerable system flexibility. TCAC systems are operating a distant object. suc- The rangefinder has an emission wavelength of 1.06 microns, cessfully with the U.S. Army in Europe. a range of 200 to 9990 meters, and a range error of ±10 meters. The REMBASS program is an Army program started in It features built-in self -checking and is a highly reliablerange- the mid -seventies to provide a detection system for useon the finder with greater than 30,000 mean rangings between failures. battlefield. The REMBASS system consists of three main subsys- Since 1974, almost 7,000 rangefinders have been ordered and tems-the sensors, repeaters, and monitoring equipment. Infor- over 5,200 have been produced. The David Samoff Award was mation picked up by the various sensors is transmitted over a received for work on this project in 1978. VHF data link to manned monitoring sets, either directlyor via Building on our experience gained through programs like repeaters t -be on the ground or in aircraft. TCAC, REMBASS and AN/GVS-5, work has begun - e system can be deployed with only one or more sen- on system concepts to support all Tactical C3I missions and selected Stra- sors. The number is limited only by the available frequencies Nis tegic C3I missions. The scope of these C3I concepts involves all and the operator's capability to integrate the information. of the advanced technology areas discussed earlier. REMBASS is a passive system. It uses magnetic, infrared, seis- Automated Systems has been and continues to be in the mic/acoustic, analog, and strain -cable sensing devices. Trans- forefront of the high-tech field. Our accomplishments in the missions are in short bursts that provide a low electromagnetic early space program, Automatic Test Systems, Vehicle Test Sys- profile, and make detection difficult. Once emplaced, thesensors are unattended for long periods of time. tems, and C3I Systems, along with our long history of producing high -quality, low-cost products for the military, has resulted in Repeaters are required to overcome range limitations and the explosive growth we are experiencing today. line -of -sight obstacles between sensors and monitor; singleor We have over 100 military contracts and will continueto expand our leadership role in all of our systems areas. Oursea- soned professionals are blending their expertise with that of talented new people to assure an expansion of our techno gical expertise that will keep us in the fast lane of America's hnol- ogy Highway. R.N. Hurst K.H. Powers

The development of international televisionstandards

Thanks to a serendipitous shift in theAmerican color- subcarrier frequency 30 years ago, a compositedigital sampling frequency relating the American and Europeantelevision standards has been found today.

tee); the 625 -line, 25 -picture -per -second stan- Television isa surprisingly ancient tech- method, the receiver needed to have an dard originated in Europe (known as PAL, nology. Although many people firmly be- exactly matched disc with exactly the same lieve that TV began in the 1950s era of number of holes, spinning at exactly the for Phase -Alternate Line); and the French - conceived 625 -line system known as Kukla, Fran, and 011ie, the fundamental same speed. This need for identical scan- development of the technology actually ning at transmitter and receiver created a SECAM, from the French acronym de- took place in the nineteenth century. In "lock -and -key" arrangement; a receiver not scribing its unique method of transmitting fact, one of the more significant mile- constructed to be identical to the transmit- color signals. As satellite interconnections proliferated, and as the exchange of tapes stones-the invention of live scanning of a ter would be "blind" to the transmitted the picture-was conceived and patented by images. And, although television technol- among nations became commonplace, Paul Nipkow nearly 100 years ago, in ogy quickly moved from mechanical scan- industry developed large converter racks that could translate between standards, but 1884. ning with a disc to modern all -electronic these were very expensive and more than Nipkow's elegantly simple invention-a scanning, the "lock -and -key" situation re- rotating disc, filled with holes set in a spi- mained characteristic of television. a little inconvenient to use. ral, that caused a flying spot of light to Unfortunately, television's development Furthermore, the manufacturers of tele- probe the object to be televised-was the was not coordinated among thevarious vision equipment, most of whom addressed the worldwide market, found themselves key to practical television, and formed the countries during the industry's formative basis for the first actual transmission of years, and the "locks" and their corres- burdened with the expense of producing three different versions of their basic designs, pictures nearly 45 years later. However, to ponding "keys" were different in the var- reconstruct the pictures scanned by this ious countries. At first, this was not thought which raised the cost of all three versions. to be a serious problem, since everyone This sorry state of affairs seemed to be thought that both distances and language doomed to permanence, since the public's Abstract:The authors briefly review the barriers would preclude the exchange of billions of dollars worth of receivers could history of television standards as back- programs among nations, anyway. Butvideo- not be made obsolete by abruptly and ground for their history of digital television tape recording and satellite transmission arbitrarily changing to a common standard. standards on both sides of the Atlantic demonstrated that the inability to exchange That would be unreasonable. Ocean. Component encoding's advantages video signals among nations was indeed a over composite encoding are explained serious problem and was one destined to The authors describe the efforts of the get worse, not better. History of digital transmission European Broadcasting Union, the Society However, the seeds of an opportunity for of Motion Picture and Television Engi- Television transmission standards change had been sown in 1949 at Bell neers, and most recently, theComite Con- Telephone Laboratories. In that year, a sultatif International des Radiocommuni- For several decades, the television industry has tolerated the existence of three major researcher named W.M. Goodall transmit- cations, now on the road to a true ted television pictures using digital tech- international digital transmission standard standards of picture transmission-the 525 - line, 30 -picture -per -second standard devel- niques, and reported his results in a paper n1983 RCA Corporation oped in the United States (called NTSC, delivered at the National Convention of Final manuscript received July 25. 1983. the Institute of Radio Engineers (IRE) in Reprint RE -28-5-2 for National Television System Commit-

10 RCA Engineer 28-5 Sept./Oct. 1983 New York City, in March. The advan- ture rotations being the most -easily de- the new digital television systems did not tages of the system were clearly demon- scribed. sample and digitize the signals after they strated, but the high cost of digital trans- were in some national format, but instead mission did not, in 1949, justify the advan- did the digitization while the signal was Rise of digital standards tages gained. Mr. Goodall's work was pub- still a basic set of color signals-a form lished in the Bell System Technical Journal As television engineers continued to pursue that is common to all national standards. in January of 1951 (Vol. 30; p. 33), and this area, better and higher -speed digitizers All national standards generate three sig- the work was then quietly forgotten for soon made it possible to do conversion at nals within the camera-a luminance sig- nearly thirty years. four times the color subcarrier rate, and nal, which conveys the monochrome detail Then came the transistor, followed by new "black boxes" were built that could of the picture, and two color signals, which the integrated circuit, followed in turn by spew out 14.31818 megasamples per sec- provide the color information. These three large-scale integration, which gave rise to ond. These systems had many worthwhile signals are the basic components of the low-priced, high -capacity digital memories. advantages, and standardizing committees television signal. The national differences Suddenly, the television industry realized began writing tentative draft standards arise only when these components are en- that these new computer components would based on four-times-subcarrier digital sam- coded for transmission to receivers. The give low-cost ways to store and manipu- pling systems. encoding process places these three com- late the video signal-if it were converted Also, several groups began discussing ponents together into a composite signal; to digital form. The Bell Labs work of the "all -digital television studio," forecast- the exact make-up depends on the stan- 1949 was dusted off, and the move to dig- ing how these "black boxes" could all be dards of the country where the signal is to ital television was on. interconnected digitally to form a com- be transmitted. Initially, the conversion of a TV picture pletely digital television station. Other All the earlier "black boxes" had dig- to digits was done in a very straighforward groups were exploring the requirements of itized the composite signal; the question manner: the "composite" signal-so named digital videotape recorders for the all -digi- being asked from Europe was, "Shouldn't because it carried, on one wire, all the tal studio, while yet other organizations we, instead, digitize the basic components, luminance and color components of the were discussing the behavior of microwave so international exchange is possible?" signal-was fed into a high-speed digitizer, transmission links for the new digital tele- In addition, the Europeans pointed out, which converted the composite signal to vision signals. the quality of the pictures resulting from an 8 -bit parallel digital signal. Since the component encoding was basically super- TV signal (in the United States) has a ior to that from composite encoding. The bandwidth of 4.2 MHz, the well-known The European solution national standards -setters had years ago Nyquist criterion required that the conver- In the midst of all made some compromises, in order to sion be done at an 8.4 -MHz rate, or faster. quieting thoughts arose, chiefly from squeeze color service into existing mono- In fact, it was discovered very early that Europe. First, the Europeans noted that, chrome channels. Slavish adherence to com- the conversion rate should be a multiple of although the four -times subcarrier was in- posite digital coding carried all these compro- the color subcarrier frequency, which is deed technically very nice, four times their mises withit; component coding neatly embedded in the normal TV signal to subcarrier (which was 4.43 MHz, not 3.58 stepped around all these problems. carry the color signals. In the United States, MHz as in the U.S.) was a very large this frequency is 3.579545 MHz, so the number. The resulting torrent of digitized conversion rate of these early digital sys- television data might prove difficult to pro- The move to worldwide standards: tems was pegged at three times this fre- cess, and most certainly would be a burden Component coding quency, or 10.738635 MHz. to the data -storage capabilities of a future Thus, in early 1979, the major European Most, if not all, of these early systems digital videotape recorder. In addition, the standardizing group (the Technical Com- were "black boxes." They were self-con- microwave and satellite links would be mittee of the European Broadcasting Union, tained digital systems that received a nor- hard-pressed to handle the flood of data or EBU) and the major U.S. standardizing mal analog TV signal at their inputs, did representing a television picture sampled group (the Society of Motion Picture and all the conversion, manipulation, and recon- at this awesome rate. And the idea that an Television Engineers, or SMPTE) found version internally, and delivered a stand- all -digital television studio could be devel- themselves considering whether or not there ard analog signal at their outputs. The oped by simply expanding the boundaries might be a way to extend this concept of most common manipulation was time -base of all the black boxes till they touched, component digitizing not only to accom- correction, whereby a system receives a struck many as being uneconomical. plish European program exchange, but also "nervous," jittering signal from a video- Also, Europe viewed the advent of dig- to facilitate worldwide program exchange. tape recorder, storesit temporarily in a ital television as an opportunity to rectify The general technique used in compo- digital memory, and reclocks it from the the difficulties of program exchange be- nent coding is simple. The three compo- memory as a stabilized, nonjittering signal. tween France and neighboring countries. nents to be transmitted are Y, the wide - Later, black boxes using more digital mem- Although the basic 625 -line scanning sys- band luminance signal, and R -Y and B -Y, ory managed to eliminate the picture "roll" tem is used throughout Europe, the method the two narrowband color signals. Under seen on switching from, say, a studio sig- of transmitting color is not the same, with the Nyquist criterion, the sampling rates nal, to a signal from a sports stadium. Still the SECAM system being used in France, for each of these three components can be later developments of these systems per- Russia, and the Eastern Bloc nations, and adjusted to account for their differing band- mitted a whole new class of special effects, the PAL system being used elsewhere. Pro- widths. Since most European systems have with picture -size changes ("electronic gram exchange among these nations would a 5.5 -MHz luminance bandwidth, any sam- zoom"), left -or -right "slide -offs," and pic- be facilitated, argued several Europeans, if pling rate above 11 MHz is theoretically

Hurst/Powers: The development of international television standards 11 adequate for the Y signal, while the 1.3 - tem; the numbers would simply indicate and the frame rate of 30 Hz; the numbers MHz R -Y and WY signals can be sampled that the luminance in the proposed system were such that all critical frequencies were at any rate above 2.6 MHz. One of the would be sampled at four times the sam- interrelated. But, the field tests of the sys- earliest proposals to come from Europe pling rate of the two color signals. An tem showed that the color subcarrier and suggested that the three signals be sampled American -proposed system, which sampled the sound carrier, at 4.5 MHz, could inter- at 12 MHz for Y and 3 MHz for the two at 14.3 MHz luminance and 7.16 MHz for act noncoherently to produce an annoying color signals. This was called a 12:3:3 sys- the color signals, would be called a 4:2:2 disturbance in the signal. Spectral analysis tem, and the three numbers and their sepa- system. showed that the best way to cure the rating colons became the standard means The adoption of a neutral ratio for express- problem was to shift the sound carrier for describing all the subsequent proposals ing the luminance/color-sampling relation- slightly, or to shift the color subcarrier as well. ships aided in the determination of the slightly. Rather than risk tampering with In 1980, the SMPTE organized a Task need for a fairly high color -sampling rate the already -established sound carrier, the Force on Digital Component Coding, to for studio use, where special keying effects researchers opted to lower the color sub - act as liaison with the EBU and other are used, for example, to "cut in" a back- carrier to 3.579545 MHz. Since the scan- organizations searching for the best ap- ground behind a newscaster. Good color ning rates were tied to the subcarrier, this proach for digital television. Among the resolution is needed for this special effect, change lowered the line rate to 15,734.26 important tasks performed by this group or the fine detail of the foreground-the Hz, and dropped the frame rate to 29.97 was the issuance of a document on the hairdo of the female anchor, for exam- Hz. All this was done in the early 1950s; basic parameters of component coding. This ple-will vanish into the background. Tests no one could have possibly forecast what document became the U.S.'s submission to such as the ones performed in San Fran- a fortunate and serendipitous effect it would the CCIR (the Comite Consultatif Interna- cisco quickly established that 4:2:2 systems have thirty years later. tional des Radiocommunications), which were absolutely required for good studio In the 1980s, with Europe and America was another group, of world dimensions, work, especially where chroma keying is on the brink of losing a chance at interna- actively interested in the direction being used, while a 4:1:1 system might be per- tional digital standardization, researchers taken by developers of digital TV. In addi- fectly acceptable for common carrier trans- seeking a compromise sampling frequency tion, the SMPTE Task Force organized a mission or for field uses such as electronic between 12.0 MHz and 14.3 MHz discov- demonstration of picture quality as a func- newsgathering. ered that, thanks to the shift in color sub - tion of various types of component cod- The San Francisco tests did little, how- carrier frequency 30 years earlier, a com- ing; a well -attended demonstration that took ever, to resolve question (1)-the choice promise sampling frequency, precisely replace in San Francisco in February ofbetween the European 12 -MHz Y sam- lated to both European and American stan- 1981. pling and the U.S.-preferred 14.3 MHz. dards, existed at exactly 13.500000 MHz! There was, predictably, a slight increase in Figure 1 shows the beauty of this rela- picture quality whenever the sampling was tionship. Starting with a frequency of 13.5 Competing approaches raised from 12 to 14.3 MHz, but anyone MHz, all the frequencies of both the U.S. color system and the European PAL sys- By this time, there were many competing could question whether or not the increased approaches to component coding. The key data rate and increased system cost really tem may be derived with simple integral is even possible to derive the parameter of each proposal was the rate at resulted in enough of a picture improve- factors.It recommended audio sampling rate for an which the Y (luminance) signal was sam- ment to make it worthwhile. pled. In addition to the above 12:3:3 pro- At this point, it was entirely possible for accompanying digital audio system. posal, which sampled the luminance (Y) the worldwide standardization attempts to Tests showed that the 13.5 -MHz sys- at 12 MHz, there were other proposals founder, because the Europeans had no tem, realized as a 4:2:2 system (that means, that sampled the Y signal at the old Amer- desire to burden their systems with the of course, that the two color signals are sampled at a 6.75 -MHz rate) offers all the ican four-times-subcarrier rate of 14.3 MHz. extra bytes from the American sampling In addition, there was a variant of the rate, while the Americans had no wish to quality needed for a studio system. In the 12:3:3 system that offered better color reso- lose the added picture quality and at the fall of 1981, the system was presented to lution by sampling the color signals at 4 same time move to a sampling rate not the world communications standardizing body, the CCIR, and after much debate MHz, making a 12:4:4 system. related to the subcarrier of the American and discussion, a document was issued The contenders quickly realized that there standard. A compromise was needed, but were two separable problems under dis- the choice of compromise sampling fre- affirming the CCIR's recommendation that this system form the basis for a worldwide cussion: (1) Should the Y sampling rate be quency seemed doomed to be unrelated to the European -preferred 12 -MHz rate or either standard. digital television standard. The 158 nations the USA -preferred 14.3 -MHz rate-the lat- of the ITU (International Telecommunica- ter being based on the color subcarrier tions Union) unanimously adopted the 13.5 - Agreement on a sampling frequency frequency; and (2) What should the ratio MHz standard in a recommendation at the of the luminance sampling rate to the color It was then that serendipity came into CCIR Plenary Assembly at Geneva, in March of 1982. sampling rate(s) be? play. In the early 1950s, while American To facilitate discussion on question (2), color television standards were being devel- it was decided to express the ratioasa oped, the color subcarrier, after several The CCIR document ratio, without regard for the actual lumi- changes, had finally settled permanently (it and "Extensible Families" nance sampling rate, which could then be was thought) at 3.583125 MHz. This num- decided separately. For example, the 12:3:3 ber could be divided by appropriate num- This momentous document from the CCIR system would be referred to as a 4:1:1 sys- bers to derive the line rate of 15,750 Hz was issued under the unassuming title of

12 RCA Engineer 28-5 Sept./Oct. 1983 NTSC PAL sampling period of a 13.5 -MHz sampling SYSTEM SYSTEM signalis 0.074074... microseconds, the European scan line will have exactly 864 samples per line; the American scan line, sampled at the same rate, will contain 858 SAMPLES samples-a difference of six samples. PER LINE This difference is shown in Fig. 2. But HOR FREQUENCY the figure also shows that a period of time -15.73426 Hz HOR FREQUENCY is spent, during each line, in blanking the 15.625 Hz signal to allow for the transmission of syn- SUBCARRIER 1 135 SUBCARRIER FREQUENCY x chronizing information. These blanking pe- 2 .1 FREQUENCY -3 579545 MHz 4 433618 75 MHz riods are sufficiently different, between the LINES two standards, to permit the blanking peri- PER .111.. FRAME ods to absorballof the six -sample differ- FRAME FRAME ence between the two standards' scan lines,

FREQUENCY FREQUENCY thereby producing an identical number of 29 97 Hz 25 Hz samples during the active or picture -containing portions of the scan lines. There- fore, the CCIR Recommendation showed that each of the two systems should have exactly 720 samples during the active por- DIGITAL AUDIO SAMPLING DIGITAL AUDIO tions of the lines, with a 138 -sample blank- FREQUENCY SAMPLING FREQUENCY 48.000 Hz 48.000 Hz ing interval for the American System, and Fig.1. Thanks to the serendipitious choice of the American color subcarrier (in the a 14.4 -sample blanking interval for the Euro- 1950s), it was possible in the 1980s to choose a compromise digital sampling rate pean System. Since most of the digital sys- (13.5 MHz) that can be common to the critical frequencies of both NTSC (Ameri- tems operate and process only the active can) and PAL (European) TV systems. picture interval, making the samples per active line identical effectively produces an "Recommendation 601: Encoding Parame- change, the document went on to say, international standard on a line -for -line ters of Digital Television for Studios." The should be at the 4:2:2 level. basis. body of the recommendation called for The frequency relationships between the Since the CCIR Recommendation is de-

. . . digital coding based on the use of sampling rates and the scanning rates were scribing a digital signal, the quantizing as- one luminance and two color -difference required by the CCIR document to be pect of the system is also described in the signals. ..," and also allowed, parenthet- such that the sampling structure would not document. Basically, the document calls ically, for the encoding of the basic red, appear to move on the displayed picture. for an 8 -bit system, which makes 256 lev- green, and blue primary signals.It not The authors of the document wrote that els available for signal transmission. Sev- only called out specifically the use of a the ".. .Sampling structures should be eral of these levels must be reserved for 4:2:2 system for studio use, but also allowed spatially static." In addition, the sampling "head -room," to avoid the rather abrupt for other systems. For example, a lower - was required to be such that samples on clipping that takes place when a digital quality, lighter -weight system for field use successive scan lines should be one above transmission system runs out of dynamic could conceivably sample the color -differ- the other-a structure called orthogonal in range. Therefore, the document specifies ence signals half as often, and would, there- the document. One further requirement that only 220 of the possible 256 levels fore, be known as a 4:1:1 system. On the was laid on the sampling structure-the may be used, with level 16 corresponding other hand, a system that encoded the color samples and the luminance samples to black, and level 235, to white. primary signals directly would have to sam- should fall on top of each other spatially; In a 4:2:2 system, the two color signals ple each color signal at the maximum rate, that is, they should occur at the same time. would be sampled at half the luminance and would be a 4:4:4 system. Because of This arrangement is referred to as spatial rate, which is 6.75 MHz. This arrange- the simple relationship among the various co -siting of samples. ment produces 360 samples per line for sampling rates, the signals of one system each of the color signals, co -sited with the could easily be converted to the signal 720 luminance samples. Each color signal format of one of the other systems. For Solving the scan -time problem is also allocated 8 bits, but can use 224 of example, a 4:1:1 signal recorded in the All these provisions of the document estab- the 256 possible quantization levels, with field could be transcoded to a 4:2:2 system lished an excellent family of extensible cod- the zero level of these bidirectional signals when the field tape was brought to the ing standards at the component -sampling occurring at the 128th level. studio for airing. level. However, the recommendations de- The groups of standards thus related scribed thus far do not actually produce were called "Extensible Families," and the an international standard. The times taken Vertical rate CCIR document allowed for their "...es- to scan one TV line, from left to right Although the document provides many of tablishment and evolution," further speci- across a picture, are different in Europe the needed provisions for a true interna- fying that "It should be possible to inter- and America. In Europe, the scan time is tional standard,it cannot and does not face simply between any two members of exactly 64 microseconds; in America, it is address one of the remaining problems- the family." International program ex - 63.5555555. .. microseconds. Since the that of the vertical rate: the rate at which

Hurst/Powers: The development of international television standards 13 frequencies of the various countries. The standard as written does not expunge this historical difficulty directly. However, the tide of technology is defi- 625/50 nitely rolling in to wipe out this residual 720 samples 12 1321 systems 132 samples problem. Users of 25 -Hz frame -rate systems have long been annoyed by the residual flicker on the screens of these systems. Leading edge of line syncs, Digital actve-line half -amplitude reference period Just within the year, companies are exper- (coincident with imentally using inexpensive whole -picture first sample) stores (frame stores) in home receivers, and displaying the received picture at a different rate, in order to eliminate the 525/60 flicker. Eventually, the widespread use of systems 122 samples 720 samples 16 these frame stores in all receivers will make (Note 2) frame rates a thing of the past; the receiver will not know or care about the rate at which the picture arrives. In fact, receivers of the future will receive data only as often as necessary, and will update the Fig. 2. Relationship between the 720 digital active -line -luminance samples and the display only to show motion. analogue sync. references for 625 -line and 525 -line systems. Although American So the document produced by CCIR- and European TV lines are of different durations, the active (picture -containing) made possible by a little serendipity in the portions may both be expressed with 720 samples, and the six -sample difference 1950s-took a great step toward the estab- between the two standards is absorbed in the blanking intervals. lishment of a true international television exchange medium. Perhaps, through this whole pictures are presented to the ulti- second; in all other countries, where either medium, international understanding can mate receiver in the home. In the U.S. and SECAM orPALis used, the rate is 25 be increased, and the squabbles that have other NTSC countries (such as Mexico, pictures per second. These choices were plagued this planet can at least be dimin- Canada, Japan, and Chile), the whole -pic- made decades ago, and were originally ished through the medium of international ture rate, or frame rate, is 30 pictures per based on the 60 -Hz and 50 -Hz power line television.

Kerns Powers was appointed Staff Vice -President, Communica- tions Research, for RCA Laboratories in Princeton, N.J., in May 1977. Dr. Powers is responsible for advanced systems research in the areas of television broadcasting, data transmission and satellite communications, and he is responsible for microwave technology development for commercial and government applications. Dr. Powers joined RCA Laboratories as a Member of the Technical Staff in 1951, to perform research in color television and on a high -resolution radar system. Dr. Powers received both B.S. and M.S. degrees in Electrical Engineering from the University of Texas in 1951 and his Sc.D. degree from Massachusetts Institute of Technology in 1956. Contact him at RCA Laboratories Princeton, N.J. TACNET: 226-2746

Bob Hurst received his B.E.E. degree from the University of Louisville in 1951. He joined RCA's Broadcast Engineering activity that same year, and participated in the development of color television equipment. From 1956 until 1972 he worked in the videotape recorder activity, designing the first transistorized subsystems used in these products. He was involved in the design of the TR-22, the first totally transistorized VTR, and also partici- Authors Powers (left) and Hurst. pated in the development of the TR-70 and the TCR-100 Car- tridge Video Recorder. Before joining the RCA Technical Training Activity in 1976, Mr. Hurst directed a group of engineers in pioneering digital televi- He holds 18 patents in the fields of color television, video sion techniques. He has written and taught a transistor -design recording, and digital television. Since 1967, Mr. Hurst has served course, and has conducted courses in color television theory, on the SMPTE Video Recording Reproduction Committee, and is semiconductor theory, videotape fundamentals, and digital televi- presently Chairman of that group's Nomenclature Committee. sion theory. He has written and presented numerous papers, and Contact him at: was a 1977 recipient of the Jesse H. Neal Award (the Business RCA Broadcast Systems Press equivalent of the Pulitzer Prize) for a series of tutorial arti- Camden, N.J. cles on digital television. TACNET: 222-2612

14 RCA Engineer 28-5 Sept./Oct. 1983 B. Astle

Teletext standards in North America

Even though receivers are not yet available, CBS and NBC have started broadcasting sophisticated teletext services inan effort to foster the growth of the new technology.

Teletext isa digital data system for trans- In VBI teletext, the broadcasters will The user selects pages via an input to mission of textual, graphic and control in- typically provide a few hundred pages includ- the teletext controller. This input may be formation intended for display on screens ing such items as news, weather, sports by remote control or front -panel access. of suitably equipped receivers. Teletext is a and entertainment information, together The teletext controller usually provides feed- one-way service in which the receiver selects with TV -program -related material such as back to the user in the form of a row of the desired information from a continuous captioning. Fig. la shows the choices avail- text information outside the teletext dis- flow of information. It is distinguished from able on NBC teletext on July 7, 1983. play area. videotex, which is a two-way service often The user will be able to select the pages of transmitted over telephone lines. interest, and thus will have a wide choice In broadcast teletext, the information is of pages immediately available, as opposed Brief history of teletext transmitted within the horizontal lines of to the sequential presentation of informa- Teletext research was begun in 1970 in the TV signal. In Vertical Blanking Inter- tion in a normal TV program. It is expected the United Kingdom (U.K.) by the British val (VBI) teletext, the information is trans- that the service will be supported by adver- Broadcasting Corp. (BBC) and Indepen- mitted only during the vertical blanking tising, and thus will be free to the viewer dent Broadcasting Authority (IBA). The interval, and is designed not to interfere who owns a teletext receiver. U.K. teletext standard was defined in 1974. with current TV receivers. In full -field tele- A simplified schematic diagram of a It offered a basic text service together with text, all, or nearly all, of the lines in a TV broadcast teletext system is shown on page low -resolution graphics. Trials were con- field may contain teletext information. Trans- 17 in Fig. 2. ducted in 1976 and regular broadcasts commission of VBI teletext has recently been The TV station may receive teletext from menced in 1978. Those interested in further permitted by the Federal Communications its network and from other services, and details of the early history of the U.K. sys- Commission (FCC),' and is currently being may generate some locally. These are put tem are referred to the article by K. M. broadcast by the NBC and CBS television into a teletext page store. A teletext insert- McKee in an earlier issue of the RCA networks among others. Some examples er adds additional control information and Engineer.' of NBC teletext pages are shown in Fig. 1 inserts the pages into the VBI of the base- The French designed a slightly improved (see color versions on back cover). band TV video signal. The composite sig- but incompatible teletext service called nal is then filtered, modulated and trans- Antiope, which was announced in 1978. Abstract:Teletext is a new broadcast mitted. The Antiope system used asynchronous service in which digitally encoded pages of The teletext receiver demodulates the transmission, unlike the U.K. system which text and graphics are broadcast in the signal to baseband. A data processor exam- used a fixed -format synchronous transmis- vertical blanking interval of television ines each line of the baseband signal and sion in which each byte defined the char- signals and received by specially equipped reassembles the data into pages. If the acter at a fixed display location. It over- receivers. This article surveys the stan- page is wanted by the teletext controller, came one minor limitation of the U.K. dards for coding the information and dis- then it is stored in the page memory. Upon system and made itpossible to change cusses in some depth the North American command from the teletext controller, a colors between characters without using a Broadcast Teletext Specification. display processor reads the stored code space. Although trials of Antiope were from the page memory, processes it, and conducted it never became a regular service. C1983 RCA Corporation feeds the result to a mixer switch, which Final manuscript received July 27, 1983. Telidon, a teletext system having signif- Reprint RE -28-5-3 overlays it on the TV video. icantly greater graphic capability than either

RCA Engineer 28-5 Sept./Oct. 1983 15 TONY'S HIGH, 88 in Nagadoches, T e NBC -TELETEXT TOM'S LOW 32 in Duluth. Minn 30s 40s

NEhiSFROMT 2 50s WEATHER 9 SPORTS 10 MONEY 16 PLAYTIME 60s PEOPLE 25 -OUR BODY 31 FOR SPEC:_ LIVING 36 ?Os STARS 41 SEE PAGES -P ON DECODERS R; ".4E SOAPS 46 RCA 3 GAMES 50 TOs IORNER 55 80s JULY '983 411! *N3t :-:-IERS- 62 MIN 511011 April 7. 1983 _C'ITS 79

Fig.1a. The main NBC index page. The primary character Fig.1b.A national weather map. This map illustrates the set was used to produce the small text and numbers.The intermixing of text and graphics. The outline of the United larger "PLAYTIME" was constructed using the double -size States was drawn using a filled polygon. The borders be- control from the CO control set. The different font in "NBC tween the states were drawn with concatenated lines using TELETEXT" was constructed using lines with a larger logi- a small logical pel, whereas the temperature contours were cal pel. The colored shapes underneath the title were con- drawn with a larger logical pel to produce the thicker lines. structed using filled polygons (see color versions on back The rain area was drawn on top of the map using a filled cover). The text of the contents is presented on a light gray polygon with a vertical -hatch -texture pattern. rectangle drawn with highlight turned on to produce the blue border. Additional blue lines were drawn to give the appearance of overlapping rectangles.

Fun&EamQs 50 THE SUN WILL COME OUT Most of us give Clark 6able credit for having the last word as Rhett Butler in 6011E WITHTHE WIND. Who really had thelast AMER: words and what were 1.1IVIEM LEIGH they? AS SCARLETT YOU HAVE TEM O'HARA, 'AFTER SECONDS :00 ALL ,TOMORROW IS ANOTHER DAY.'NEXT: SOREHORSEF

E E _

Fig. 1c. Apage from the fun -and -games section. A series of Fig. 1d.An elaborate rendition of a "Return of the Jedi" one -second wait standards were used to produce aclock poster. It could be used to illustrate a movie reviews section. counting down from 10 to 0, at which point the answer was Several intensities of blue were used in the color map to automatically shown. produce the shading effect.

the U.K. orAntiope systems, was an-evaluate the different teletext systems for and Telegraph ( AT&T) announced the nounced by Canada in 1978. Telidon intro- use in the United States (U.S.). CBS con- Presentation Level Protocol (PLP),4 which duced the concept of Picture Drawing In- ducted field trials of the U.K. and Antiope combined the presentation levels of the structions (PDIs), which allowed cartoon - systems in 1979, and in 1980 petitioned U.K., Antiope, and Telidon systems. CBS like geometnc drawings to be transmitted the FCC to adopt an Antiope system for added some Antiope-like communication with reasonable efficiency. It also had much the U.S. Early in 1981 the U.K. petitioned protocols to the PLP and announced the greater color capability than the earlier the FCC to recognize an adaptation of result as the North American Broadcast Teletext Specification (NABTS) in June systems. their system for North America.' Field In 1979 an Electronic Industries Asso- trials of Telidon were conducted in Canada. 1981.5 In July of that year they petitioned ciation (EIA) committee was formed to In May of 1981, American Telephone the FCC to adopt the NABTS. In Canada

Sept./Oct. 1983 16 RCA Engineer 28-5 worked in conjunction with the Canadian Standards Association (CSA) to develop TV NETWORK NETWORK the PLP into the North American Presen- NETWORK TT PAGES VIDEO tation Level Protocol Syntax (NAPLPS). No similar U.S. standardization effort was being pushed for the U.K. system. In July

LOCAL BASEBAND LOCAL of 1982 the U.S. State Department's Study TT PAGES VIDEO VIDEO Groups A & B unanimously approved the TV STATION June draft of the NAPLPS as the official U.S. position to take before the Interna- TELETEXT TELETEXT RF TRANSMITTER tional Telegraph and Telephone Consulta- PAGE STORE INSERTER MODULATOR OUTPUT tive Committee (CCITT). In the same month the draft NAPLPS became a preliminary Canadian standard T500.7

TELETEXT DECODER The EIA established a Special Working Group to develop the NABTS as an EIA- TUNER recommended practice. This was done with & IF the understanding that the NABTS might be one of several possible EIA-recom- DATA FBASEBANDNTSC TELETEXT -111. mended practices, and that the purpose of AND TV PROCESSOR 8 the Group was not to make a decision RECEIVER VIDEO between the contending systems. In reality PROCESSOR this became the major EIA teletext activ-

ROB ity, and EIA consideration of the U.K. system came to a virtual halt. In October of TELETEXT PAGE DISPLAY RGB MIXER CONTROLLER MEMORY PROCESSOR SWITCH 1982, the EIA approved a subset of the f NAPLPS selected by the Special Working ROB Group as the display part of the the initial USER CRT INTERFACE teletext service. The EIA Special Working DISPLAY Group joined the ANSI and CSA Work- ing Groups and all reached unanimous agreement on a revised draft of the USER[ ACTION DECISION 1. COGITATION PERCEPTION NAPLPS in June 1983.8 In May 1983, the FCC released a Report and Order' authorizing teletext transmis- Fig. 2.Broadcast teletext system. Each television station may receive teletextpages sions by TV stations along the lines pro- from a TV network or other source, and may create or update some pages locally. posed in the NPRM. The delays that took These are transmitted to a teletext receiver. The teletext receiver shown here is a place before thisreport was released TV receiver with a built-in teletext decoder. An alternative teletext receiver would worked inexorably in favor of NABTS be a stand-alone unit that decodes the teletext pages and remodulates them to an since memory and processor costs continued NTSC signal as an input to a TV receiver. their relentless decline, and the NABTS specification moved further towards finali- the government officially adopted standard FCC. RCA filed comments recommend- zation and approval. The FCC did not BS -14,6 which defined a teletext service ing that the FCC adopt a single system specify the coding scheme of the teletext identical to that of the CBS NABTS. and, among single systems, supported the service, and thus permitted an open -market The FCC finally took action in Novem- NABTS. approach to coding standards. Teletext sig- ber 1981 and released a Notice of Pro- The proponents of the two systems hotly nals were permitted on lines 14 through posed Rule Making (NPRM) to consider argued the merits of their systems in all 18 and on line 20 immediately, and on authorizing TV stations to broadcast tele- available forums. The U.K.-system propo- lines 10 through 13 beginning in 1988. text services. The NPRM proposed, among nents argued that their system was cheaper, These lines are not reserved exclusively for other things, not to regulate the actual tele- more resistant to transmission errors, and teletext. Line 21 will be reserved for cap- text coding scheme and thus to allow both available immediately. The NABTS propo- tioning until 1988, at which time the use the U.K. and NABTS teletext systems to nents argued that their system offered of line 21 will be re-examined. The defini- be broadcast. The Commissioners argued greater performance and that the cost dif- tion of teletext was broadened from the that choosing one of the two contending ferential would eventually be negligible. proposed definition in the NPRM to include systems would delay the introduction of a The EIA, the logical forum for settling data "intended to enhance the use of tele- service for several years while the merits such debates, became completely dead- text information." The FCC requires that of each were debated, and that this would locked. But events were moving in favor there be no out -of -band signals and no not be in the best public interest. It thus of the NABTS on other fronts. AT&T interference with present television signals. opened the way for a free-market compe- submitted the PLP to the American Na- It specifies maximum amplitude. It requires tition between the two systems. A large tional Standards Institute (ANSI) for stan- precedence of emergency visual messages. number of comments were received by the dardization. ANSI set up a group that It defines teletext as an ancillary service,

Astle: Teletext standards in North America 17 NBC offers teletext NBC launched its Network Teletext service on May 16, 1983, at its Affiliate Meeting in Los Angeles, shortly after the FCC authorized the commercial broadcast of teletext on the vertical blanking interval (VBI). When it launched the service, NBC had in place the technology to support NABTS, the high - resolution standard that NBC believes is essential for a commercially viable teletext service.We are now broadcasting a 50 -page magazine nationally on lines 15 and 16 of the network VBI. NBC teletext is an over -the -air broadcast service, free to all viewers. Teletext will require that specially equipped TV sets receive the digital information carried on the broadcast signal and translate it into a video display in the form of graphics and text. Manufacturers are expected to provide set -top Artists generate NBC teletext graphics on terminals. adapters as well as new TV sets with built-in decoders. The NBC service will be totally advertising - provide rapidly changing information at a low cost. revenue supported. For others, it simply means low-cost, paperless dis- Consumer decoders are not now available, tribution. For marketers, it provides another, and although a number of manufacturers are planning lower cost, vehicle for presenting a message to the product introductions. In the absence of consumer home viewer. decoders, a basic question naturally arises: "Why Teletext will succeed by providing a product are we broadcasting a service when no oneis that will meet consumers' needs and that will attract watching?" In the industry, this has been referred to revenue. The packaging and promoting of teletext as the "Chicken and Egg" problem andhas occu- will be a major thrust for the industry over the next pied much print space in the past. The answer is few years. Developing consumer awareness of tele- fairly simple and has a parallel in the early days of text's potential will be essential both to create television. The market will be service driven-con- demand for decoders and to build the industry. Early sumers will "buy" teletext because it has aninforma- purchasers are likely to be those attracted by new tion and entertainment value for them. They won't gadgetry and those who make heavy use of cable buy equipment that will make teletext available to and print media. them unless they are aware of, and place value on, Quite quickly, however, the market should that service. achieve a broader base. Once the initial challenge of In the long-term, we expect teletext capability to creating consumer awareness is met-generating be built into all television sets, and to have become demand for initial purchase-the challenge for NBC an expected part of a household's daily life.We see will shift to building usage. teletext, in the future, as omnipresent as the TV set During the next few years, NBC will be develop- and the daily newspaper are today. The question ing its product concept and promoting teletext in the facing NBC and the industry as a whole is how to public arena. While it builds the demand for decod- develop this new marketplace. ers as well as new TV sets, it also will be developing Teletext fills a consumer need for timely, con- a product that will hold and expand consumer cise, and convenient information. It is more readily interest. updated than any print media. It is punchy and to the point. And it's there, in the home. Teletext can also be viewed as a new and alternative distribution -Barbara Watson mechanism for current providers of information and NBC Teletext entertainment. For many, it means the capability to New York, New York

18 RCA Engineer 28-5 Sept./Oct. 1983 thus allowing cable companies to strip tele- In 1982 RCA became an active partic- at the expense of transmission efficiency. text signals, but this definition is being ipant in, and a major contributor to, the Level 1is primarily a text -transmission appealed. development of the NAPLPS and NABTS system with a primary character set plus In May of 1983, the NBC and CBS tele- standards, working through ANSI, EIA, two mosaic sets. Each mosaic set contains vision networks began transmission of and CCIR committees. the 64 graphic shapes formed by dividing NABTS teletext services. In August the a character cell into an array of blocks, Special Working Group of EIA working two horizontal by three vertical. In one set with the Canadian Videotex Consultative Present status the blocks adjoin whereas in the other Committee (CVCC) completed the draft There are two major contending systems they are separated. A fixed text resolution NABTS. for the U.S. market: the U.K. system, re- of 23 rows of 40 characters plus a page Although this discussion has concentrated cently renamed the World System, and header row is provided. Using mosiacs, on the history of the standards activities the NABTS. graphic images of resolution 80 pixels hori- within ANSI and EIA, there was, and is, The NABTS is favored by the NBC zontal by 69 pixels vertical may be ob- considerable activity in other standards fo- and CBS broadcasting networks, some local tained. A fixed palette of eight colors is rums which affects teletext. The Interna- stations, and several manufacturers includ- provided. tional Standards Organization (ISO) issued ing RCA. The NBC and CBS television Level 2 includes the addition of accents ISO 20229 on which the code -extension networks are currently broadcasting for showing languages other than English, techniques of the NAPLPS are based, and NABTS teletext services. Norpak, Pana- smoothed mosaics for enhancing the appear- is actively revising the standard to include sonic, RCA, Sony, and VSA (Videographic ance of mosaic graphics, and the inclusion the added functional requirements of the Systems of America) have shown proto- of 16 pastel colors. NAPLPS. For example, ISO 2022 permits type NABTS receivers or decoders. Time Level 3 includes the addition of a Dynam- only sets of 94 characters whereas the PDI Inc. is currently conducting trials of an ically Redefinable Character Set (DRCS) character set in the NAPLPS requires 96 NABTS-compatible full -field teletext ser- that allows other character shapes to be characters. ISO has also defined the basic vice on two cable systems. The U.K. sys- downloaded by the broadcaster and inter- layered model upon which the NABTS is tem is favored by some local stations, mixed with the predefined characters. Level based.0 The International Radio Consul- Zenith Radio Corporation, and several 4 includes alphageometric coding that al- tative Committee (CCIR) is developing cable systems. Taft in Cincinnati is cur- lows geometric images consisting of lines, teletext standards.11 ,12 Further details on rently broadcasting the U.K. system level rectangles, polygons, circles and arcs to be the historyof the PLPS can be found in 1 (see the next section), and compatible drawn. Level 5, which is not yet com- Reference 13. decoders manufactured by Zenith can be pletely specified, will include alphaphoto- purchased for about $300. graphic coding to obtain high -resolution History of teletext atRCA The first three levels of the U.K. system full -color images. RCA explored the use of the VBI for are specified in Reference 11, together with analog transmission of information during an experimental version of level 4. Level 5 NorthAmerican Broadcast the 1960s with a system called Homefax." is not yet completely specified. Teletext Specification (NABTS) After that project ended, little work was The NABTS service is defined by the done at RCA until a corporate Teletext "North American Broadcast Television Spec- The NABTS is specified by the EIA. It is Committee was established in the Fall of ification" from the Electronic Industries primarily concerned with the interface be- 1980. This committee reported in March Association. The NABTS is in draft form tween the broadcaster and the TV receiver. 1981 recommending that teletext work be and has been approved by the joint But NABTS also specifies some receiver started and that an asynchronous system EIA/CVCC Special Working Group. Ap- processes, together with some features of be supported for the U.S. It stated that, of proval by the EIA as a recommended the interface between the receiver and the the existing system proposals, the Antiope practice is expected to be completed in the user. system came closest to meeting its criteria fall of 1983. The presentation layer of the Although the teletext service is a one- for an optimum system, but suggested that NABTS is defined by the NAPLPS.8 The way service, the NABTS contains func- some high -resolution graphics be included NAPLPS has completed its public com- tions to increase the interaction between in the initial decoders. ment period. It is expected that the ANSI the user and the broadcast teletext data RCA Laboratories researchers started tech- technical approval process will also be com- base, and to give the broadcaster control nical work in 1981, putting together simu- pleted in the fall of 1983. Some details of of the structuring of this data base. The lation systems for evaluation and demon- the U.K. and NABTS teletext systems are functions provided to the broadcaster are stration. They also evaluated hardware and given in the following sections. quite extensive and there are sometimes software designs for teletext receivers in several ways of achieving the same end order to contribute to the cost -performance result. These complexities are hidden from tradeoffs to be made in the development United Kingdom (U.K.) the user, whose perceptual model of the of standards. teletext system teletext service may be quite simple. At the end of 1981 RCA filed Com- The U.K. system, as modified for North The NABTS is divided into chapters ments to the FCC NPRM strongly recom- America, is specified in CCIR Report 957.11 that correspond approximately to the lay- mending the adoption of a single standard, It is divided into five levels. These corres- ers of the Open Systems Interconnection and favoring the NABTS as the basis for pond to performance levels, not to the (OSI) model.° In this model the layers such a standard. RCA has also evaluated Open System Interconnection (OSI) lev- are independent of one another. The dif- the ruggedness of the competing systems els. These levels are upwards compatible ferent layers of the NABTS are described for the EIA. with each other, a compatibility achieved in Table I.

Astle: Teletext standards in North America 19 Layers of theNABTS The data transmission layer specifies the physical format in which the bits of Table I.The seven functional layers of the teletext service. information are transmitted. This layer is also regulated by the FCC Report and Layer Teletext functions Order.' The FCC specifies the TV -data - Application Provides a teletext service to the user, line use and sets maximum amplitude lev- 7 allows the broadcaster to structure it, and allows the user to access it. els. The NABTS completes the description of this layer by specifying the bit rate Presentation Provides instructions for presenting (5.73 Mbits per second), the bit timing, 6 visual information, and conveys additional information to the application layer. and the pulse shape. Teletext record Provides a unit of presentation code (a The data line consists of a string of 288 5 record) together with identifying and descriptive information. bits transmitted within one TV line. The structure of the data line is shown in Fig. Data group Provides a data unit consisting of a 3. The first 24 bits of the data line consti- 4 number of data blocks. tute the synchronization sequence and the Data packet Provides blocks of error -corrected data remaining 264 bits constitute the data pack- 3 for a given packet address. et The first 16 bits of the synchronization Data line Provides packets consisting of 33 bytes. sequence are the clock synchronization se- 2 quence, which consists of an alternating Data sequence of ones and zeros. The remaining 1 transmission Provides a bit stream in a TV scan line. eight bits constitute the framing code, which defines the start of the byte sequence. For broadcast teletext this framing code is 11100111, which was chosen to allow detection even in the presence of a one -bit error.

The data packet is the group of 33 eight - REF IRE CLOCK bit bytes following the synchronization se- WHITE UNITS SYNC quence in the data line. One bit of each LEVEL IN-, FRAM NG byte is used to provide odd parity. Each CODE

TO data packet starts with a packet prefix consisting of five bytes. The remaining bytes 10.5'1 0.34 USEC are divided between a data block and a

20 suffix. BLANKING COLOR The packet prefix bytes are protected LEVEL 0 BURST by Hamming encoding. The first three bytes -20 of the packet prefix define the packet ad- SYNC. LEVEL 40 dress, which defines thedatachannel num- SYNC ber. The next byte is the continuity index, FRONT which increments each time a packet of PORCH the same address is transmitted and can be used by receivers to detect missing packets. The last byte of the packet prefix indicates how the remaining bytes are divided be- SUFFIX tween the data block and the suffix. The V suffix contains information that can be COLOR PREFIX DATA BLOCK BURST 5 BYTES used to detect and correct transmission errors in the data block.

1 1 1 1 1 LINE SYNC DATA PACKET The data group consists of an integral

DATA LINE number of data blocks as shown in Fig. 4. TV LINE The data group is divided into a data group headeranddata group data. The datagroup header contains eight bytes that define, among other things, the size of the Fig.3. Structure of the data line. The data line is that part of a TV scan line which contains digital data. The first part of the data line consists of alternating l's and O's data group and the size of the last block. for bit -timing synchronization. The next part is a framing code for byte synchronization. The remaining part is the data packet, which consists of a prefix, a data block, The teletext record is the data group data. and a suffix. Each record is divided into two parts: a

20 RCA Engineer 28-5 Sept./Oct. 1983 record header and record data. The record header consists of five fixed -format bytes followed by a variable number of exten- LAST BLOCK-.j sion bytes. The first fixed -format byte defines the record type, which conveys general DATA BLOCKS information about the record. Record type LAST BLOCK SIZE I- 0 is used in cyclic teletext where all the DATA CriOUP records are broadcast periodically with only occasional changes. Record type 1is used DATA- GROUP DATA GROUP DATA . in non -cyclic teletext such as captioning. HEADER Record type 2 is an application record that DATA GROUP contains control instructions for the receiver together with general information about the service. Application records do not Fig. 4. Data group. A data group consists of an integral number of data blocks. It is contain presentation information as do the divided into a data group header, data group data, and perhaps some unused other records. Record type 3 denotes an bytes in the last block. The data group header contains control information. The important record that must be examined data group data constitute a teletext record. by the receiver such as an alarm record The second fixed -format byte in the rec- flag in a data channel, the entire display complexity has been built into the NABTS, ord header indicates the presence of one bit map iscleared to transparent. This the complexity has been concealed from or more optional extension fields. allows the associated TV video to show the user as far as possible. Thus, when a The remaining three fixed -format bytes through the bit map. Code in the caption user invokes the next page, a number of in the record header define part of the record is then executed and the resulting structures will be examined by the receiver record address. An additional six bytes of caption message displayed. Captions may to determine the address of the next page. address may be present in the header exten- consist of graphics in addition to text. The exact method by which the receiver sion. Thus record addresses may take two The delay flag instructs the receiver not determines the next page is concealed from forms, a short form consisting of three to present the information immediately but the user. hexadecimal digits, and a long form con- to wait until a reveal record, also identi- In cyclic teletext the start of a cycle is sisting of nine hexadecimal digits. Each fied by flags, is received. This allows, for marked by a cyclic marker flag. This may short address has a long form obtained by example, several versions of a caption to be used by receivers to determine the ab- adding four leading zeros and two trailing be transmitted, perhaps more than once to sence of pages. For example, if a receiver zeros. Records are also identified by the aid error recovery, and then all versions to is searching for a user -requested page and packet address, which defines a data chan- be revealed at the same time in synchroni- two cyclic marker flags are found, then nel. Within each data channel there are zation with the TV program. the receiver can be reasonably certain that therefore over 68 billion different addresses. An index flag indicates that the record the page is not present in the cycle and Even if only decimal digits are used, there is an index record. A receiver will nor-can give an appropriate message to the are one -billion different addresses. This is mally keep a log of index records seen by user. considerably more space than is needed by the user, so when the user requests an The broadcaster can inform the receiver VBI teletext, and somewhat more than is index page he will be shown the last one to automatically acquire and show a num- needed by full -field teletext, but it allows he saw. There is provision for the broad- ber of records by using the auto acquire for future expansion to large data bases caster to specifically define an index page flag. If the auto acquire flag is high, then and gives the broadcaster considerable free- number for any page, and there is also a the receiver will acquire and show the dom in structuring his data base. default index structure. more record without user intervention. The Each record's length is limited to allow In addition to direct page access, the broadcaster can also inform the receiver of receivers to allocate a specific amount of user is provided with next and more func- the addresses of records that should be memory for the capture and storage of tions, which are two easy ways to advance precaptured since they are related to the records. Records may be linked together through the teletext data base. The next present record and may be needed by the to allow the broadcasters to compose pages function, activated by a single key, is in- user. that have lengths of more than this limit. tended to advance the user to the next To increase the transmission efficiency Information on this linking is contained in topic, whereas the more function is intend- of the service, a support record has been the record -header extension. Receivers will ed to give the user more information on included in the NABTS. This record, which automatically capture and present all rec- the same topic. The record header con- is identified by a flag, is executed prior to ords in a linked series, so that the user will tains provisions allowing the broadcaster the execution of any record that has a normally be unaware of the structure. to designate any other record in the ser- support needed flag set high. Particular types of record are marked in vice as the next or more page. The addresses Two flags, the alarmandpriority flags, the record header by a set of flags. The of the next and more records may also be are used in combination to mark records caption flag indicates that the record con- defined by some previous record giving that must be shown if the receiver is in the tains a caption message intended to be the broadcaster great flexibility in structur- teletext mode or in the television mode, shown over TV video. This instructs the ing the broadcast teletext data base. and records that are reveal records, that is, receiver to put black, white, and "trans- This illustrates a general principle that records that cause all delayed records to parent" colors into its color map. The first was followed in defining the NABTS. Al- be shown. time that a receiver encounters a caption though considerable power and inevitable An update flag is used to indicate that a

Astle: Teletext standards in North America 21 record is being frequently updated, as in ings and for changing the color. A mosaic are useful in achieving animation effects. captioning. The version number of a record set is based on that of the U.K. system and The teletext SRM specifies that a min- may also be contained in the record header. can be shown in both contiguous and sepa- imum of 16 simultaneous colors out of a This is a number from zero through 15 rated modes corresponding to the two U.K. palette of 512 colors must be supported by that is changed by the broadcaster whe- level -1 mosaic sets. A macro set allows the receivers.Itspecifies that the minimum never the contents of the record are defmition of self-contained units of PLPS display resolution of receivers must be ap- changed. If a record has an update flag set code and is very useful for increasing trans- proximately 256 pixels horizontal by 200 high, then the receiver will continually reac- mission efficiency. A Dynamically Redefin- pixels vertical. It is instructive to examine quire that record, and display it if the ver- able Character Set (DRCS) allows other the pages in Fig.1 (see color reproduc- sion number has changed. character shapes to be downloaded by the tions on the back cover of this issue) to broadcaster and intermixed with the prede- see how they are coded in NAPLPS. Those fined characters. Two control sets are pro- who wish to learn more about the NAPLPS Presentation code. The record data may vided. Control set CO contains cursor move- can read the excellent series of articles in provide a unit of presentation code identi- ment controls, code extension controls and Byte magazine.'8 fied by address, linkage, and version num- other miscellaneous controls. Control set ber. The coding of the presentation code CI contains macro -definition controls; text - The application layer of the NABTS follows that of the NAPLPS. size controls; cursor -style controls; word- specifies the teletext services provided to The NAPLPS defines the coding of the wrap, underline and scrolling controls; and the user, the structure of the service, and graphical and textual information seen by other controls. the method by which the user controls it. the user. The NAPLPS specifies the coor- The PDI set of the NAPLPS provides It uses functions provided by the lower dinate system used, the coding architecture instructions for drawing geometric figures, layers of the service. The user perceives and the detailed coding for both 7 -bit and and for controlling the attributes of these the service as consisting of a number of 8 -bit environments. In broadcast teletext, figures and of alphanumeric text. It uses a magazines each divided into pages. A maga- one bit of each byte is used for parity, thus mixture of commands (opcodes) and data zine is identical to a data channel that is the coding takes place in a 7 -bit environ- (operands). The geometric drawing primi- defined by the packet address. A page ment. The NAPLPS includes a confor- tives are line, point, arc (which includes may consist of a single record or several mance section, which specifies the require- circle as a special case), rectangle and poly- records linked together and shown to the ments that systems must meet if they are gon. These primitives are drawn by trac- user as a unit. to claim conformance with NAPLPS. It ing out an area called a logical pel. The The application layer specifies several contains a complete listing of the prede- width and height of the logical pel may be service functions, such as next, more and fined displayable characters called the gra- controlled by the broadcaster. The effect is index, that have already been described. It phic character repertoire. A teletext Ser- like having a selection of different -size specifies the option function, which allows vice Reference Model (SRM) is contained paintbrushes. The PDIs are controlled by a user to enter a key sequence to select in an appendix. This SRM specifies the the attribute -control functions and may be from a broadcaster -defined menu. Selec- minimum functions of receivers and the drawn in several ways. Lines may be drawn tion of the menu item may result in further maximum functions to be used by broad- solid, dotted, dashed, or dotted and dashed. code in the same page being executed, or casters. Geometric shapes may be drawn as out- in the acquisition of other pages. Thus, the The NAPLPS uses a coordinate system lines or may be filled with a solid color or option function can be used to build a based on a unit screen with x and y coor- with a texture of two colors. The textures tree -structured data base, or to give the dinates having values from 0 to1. The may be selected from a predefined set or user control over the display for such inter- display area is defined as the area within may be downloaded by the broadcaster. active purposes as playing games. which the broadcaster may write. Receiv- The filled shapes may be outlined (this is Video program enhancement allows broad- ers must make the entire display area vis- called highlighting). casters to instruct teletext receivers to dis- ible to the user. The display area is similar Text may be drawn in different orienta- play messages over TV video. It can be to the safe titlearea;15 broadcasters are tions, and the character path may be in used, for example, to provide local tele- guaranteed that all the display area will be different directions independent of the char- phone numbers for national advertisements. visible to the user. The receiver manufac- acter orientation. The spacing between char- Another function provided by the ser- turer will normally make the display area acters and between character rows can be vice is flash. This is used to present infor- smaller than the raster. The display area is controlled. The spacing can be set to one mation to a user upon request while the defined in the teletext SRM as having a of three predefined spacings or can be user is watching a regular TV program. width equal to that of the unit screen and made proportional in which the thinnest The information might consist of news a height approximately three quarters of letters occupy the least space. The horizon- headlines on a fast -breaking news story, or the unit screen. tal and vertical character sizes can be con- the latest sports scores as they are updated. The basic coding scheme employs char- trolled independently. The application layer defines in a general acter sets and control sets that are accessed The PDI set also contains instructions way the user interface to the service . The by code -extension techniques compatible for controlling the color. It allows multi- specification is deliberately incomplete since with ISO 2022.16,9 The primary character ple -blink processes to be established where- the service may interact with other ser- set is ASCII". A supplementary character by colors can be changed in a regular vices and devices at the receiver. set adds many useful symbols and charac- repeating manner. A wait command causes The coding of transmit macros, which ters from other Latin -based languages. The the PLPS drawing process to stop for a are defined at the presentation level,is Picture Description Instruction (PDI) set length of time determined by the broad- specified. Transmit macros define jumps to contains instructions for geometric draw- caster. Both the blink and wait commands other pages and define linkages from option

22 RCA Engineer 28-5 Sept./Oct. 1983 keys to macros. They may be combined include direct page access, and the nex4 an entry into the color map. The color so that the selection of a particular option more, index and caption functions. The map contains 16 colors that may be any instructs the receiver to acquire another ways in which the broadcaster may prompt 16 from a much larger palette, typically page. for these functions are defined. Some recom- 512 (29) or 4096 (2t2) colors obtained by The functions provided by the NABTS mendations for key labeling are also given. allocating three or four bits to each of the can be used to provide a class of interac- This will improve consistency between re- three primaries red, green, and blue. Thus, tive games. The ability to link arbitrary ceivers without restricting receiver manu- four bits of information from each pixel of macros to keys, coupled with the ability of facturers from following their own designs. the bit map are converted into 9 or 12 bits macros to invoke other macros, to execute of color information. The output of the PLPS code, to redefine the key linkages color map is fed to a mixer switch that and to jump to other pages, allows quite Comparison of NABTS overlays the output of the color map on complex games to be defined. For exam- and U.K. teletext systems the TV video upon command from the ple, a key linked to a macro that moves The NABTS teletext system, as specified teletext controller. the drawing point a relative distance and in the EIA NABTS," and the U.K. tele- In normal teletext mode the color -map then draws an object at the new position text system for North America, as speci- output completely overlays the TV video of the drawing point can be used to move fied in CCIR Report 957,3 are compared so that only teletext pages can be seen. an object around the screen. Note that the in Table II. Level 5 (alphaphotographic) The color map may, however, contain the NABTS cannot provide arcade -type games of the U.K. teletext system is not included color "transparent." When the bit map sinceitlacks such features as collision since it is not yet specified. The U.K. page references this color, the TV video is al- detection and conditional execution. header and the NABTS service row are lowed to pass through the mixer. Thus, by excluded from the display comparison. judicious use of colors, including transparent, the service can be used to overlay text Fundamental Service Specification and graphic images on TV video. This can Chapter 8 of the NABTS contains a defi- NABTSreceiver be used to provide teletext services such as nition of the Fundamental Service Specifi- The functions provided by the various lay- captioning, and to provide locally gener- cation (FSS), which defines the initial tele- ers of the NABTS can be better under- ated feedback messages when the receiver text service. It specifies limits on perfor- stood by examining the schematic diagram is in the television mode. mance of layers 1 through 7 for both the of a typical NABTS receiver shown in service provider and the receiver. It gives Fig. 5. The receiver is assumed to meet the recommendations and guidelines where lim- requirements of the FSS of the NABTS. Future prospects its are inappropriate. Some of the more A data slicer examines each line of the The NABTS is emerging as the major tele- important specifications of the FSS are the baseband signal, determines the signal level, text broadcast system for North America. interleaving of packets in full -field teletext, detects the clock synchronization sequence, The NABTS offers substantially greater the maximum size of a data group, and and produces an output consisting of a se- performance then the U.K. level 1 system, receiver -function requirements. ries of bits plus a regenerated clock. A and this is a major factor in an advertiser- Full -field teletext devotes all the TV prefix processor examines the bits from sponsored service where appearance of ad- scan lines to teletext data to the exclusion each line and looks for the framing code vertiser products and logos are important. of TV video. Only 32 of the lines in any and packet address. If the packet address The cost difference between the display field may be devoted to any given data is wanted by the teletext controller, then functions of the NABTS and U.K. level -1 channel. This restriction simplifies the hard- the packet is stored in a buffer for further receivers is projected to drop to less than ware design of teletext receivers by limit- processing. $10 by the end of this decade.19 Although ing the information flow in any data chan- The first packet in a record contains the the cost of receivers capable of decoding nel, which reduces the computational re- record address. If the record is wanted by both systems will also decrease, it is unlikely quirements. the teletext controller, then the remaining that broadcasters want to split the avail- The FSS restricts the maximum size of packets are acquired and the entire record able transmission bandwidth between them. a data group to 68 packets. This allows is stored in a record memory. Error detec- The NABTS does not completely spec- the receiver to set aside a fixed amount of tion and correction on the record may also ify all areas of the teletext service. For memory (two kilobytes) for a buffer to be performed at this point. example, it does not specify user -input meth- acquire data groups. From the receiver Upon command from the teletext con- ods. It is premature to standardize these at manufacturer's point of view this is the troller, a PLPS processor will read the present since, without extensive service ex- most logical restriction, but it does cross PLPS code from the stored record, per- perience, it is difficult to predict what forms OSI levels', since packets are at layer 3 form calculations and write into a display they can or should take. But, in a few and the data group is at layer 4. This bit map and also change a color map. The years it may be desirable to revise the inconsistency in the standard points both display bit map consists of RAM in which NABTS to include a more complete speci- to the difficulties of imposing the OSI four bits are allocated to each viewable fication of some areas. model on the real world, and to the histor- pixel.It has a resolution approximately I expect that the NABTS will be ex- ical and evolutionary nature of standards. 256 pixels horizontal by 200 pixels verti- tended to include downloading of compu- For the presentation layer, the FSS speci- cal by 4 bits deep for the broadcast image. ter programs. Although the FCC currently fies that receivers must meet the require- An additional area may be provided for prohibits this, the utility is so great that ments of the teletext Service Reference locally generated messages, giving a total there will be increasing pressures to permit Model. It also specifies the functions that bit map size of approximately 27 kilobytes. this extension. For example, the British are receivers must provide to the user. These The four bits defining each pixel indicate already transmitting computer programs as

Astle: Teletext standards in North America 23 Table II. Comparison of NABTS and U.K. teletext systems. Function NABTS U.K. Teletext System FSS level 1 level 2 level 3 level 4 Bits per line 288 290a IN - Framing code 11100111 11100100 ).- Magazines 1000b 8 )0 - Pages per magazine 1000b 100 ).- Extra pages 999999000b 3200 Version number yes no Normal text resolution` 40 X 20 40 X 23 yes ASCII yes yes yes yes Accented characters yes no yes yes yes Character sizes 47500 2 4 4 4 Character rotation yes no no no no Proportional spacing yes no no no no yes Mosaics yes yes yes yes Smooth mosaics no no yes yes yes yes DRCS yes no no yes Macros yes no no no yes yes PDIs yes no no no Graphical resolution` 256 X 200 80 X 69 80 X 69 undefined undefined yes Wait yes no no no 32 Colors 16 8 32 32 Color palette 512 8 32 4096 262144

User options 96 1 1 1 1 Key linking yes no no no no yes Next page yes yes yes yes More page yes no no no no Support record yes no no no no Application record yes no no no no

a Although specified as 290, it may be a misprint for 296. Additional hexa- b The numbers of NABTS magazines and pages are given for decimal numbering. decimal magazines and pages are available.

c Resolution is given as horizontal times vertical resolution. a supplement to educational and entertain- in purchasing a house in Middleton would the NAPLPS to add such desirable fea- ment services. Time Inc. has been devel- tell his receiver to capture and store all ads tures as font styles (for example, italics), oping software downloading protocols in containing the words "house" and different shapes for logical pel (for exam- a teletext cable environment. They may "Middleton." ple,circular), photographic capability, submit a protocol for ANSI standardiza- The captioning facility provided by the sound, and animation. In the long term, it tion. This could become a strong contender NABTS is more powerful than that pro- is possible that NAPLPS will replace ASCII for use in teletext and videotex services. A vided by the current line -21 closed -cap- as the standard coding scheme for exchang- software downloading capability will greatly tioning service.Itis expected thatthe ing information. enhance the functions of the teletext ser- NABTS captioning service will also be As memory costs continue to decline, I vice and will provide the basis for a new much less expensive to the user, and so expect more memory will be included in range of consumer and business products. will eventually replace the closed -caption- receivers allowing the storage of more pages The service may be expanded to peri- ing service. from the broadcast cycle. Pocket color TV pheral devices controlled by downloaded I believe that the ability to choose timely receivers will become cost effective and, software. For example, a printer may be and attractively presented information with- when given full teletext-including photo- used to print out discount coupons for out apparent cost will make teletext a graphic capability-could replace many of manufacturers' products. popular service, and almost all TV receiv- today's newspapers. Teletext will have a Itispossible to transmit a classified ers sold will contain NABTS decoders major impact on the performance of TV advertisement service. Such ads would be when the incremental cost becomes suffi- receivers. The ability to present digitally broadcast only a few times, perhaps only ciently low. generated information on a TV screen will once. Receivers could select among them I expect that the NAPLPS will be revised lead to improved convergence and resolu- by performing a key -word search and store to include new features in a compatible tion in receivers. It will also lead to better those that had been requested by the user. manner within the next few years. There is control of the raster position and size. Since For example, a person who was interested already pressure to expand and enhance the NAPLPS display area is rectangular, it

24 RCA Engineer 28-5 Sept./Oct. 1983 TELETEXT DECODER

TUNER

& IF BASEBAND NTSC DATA SLICER CLOCKj j BITS t PREFIX VIDEO PROCESSOR PROCESSOR

BYTES RGB Brian Astle joined the technical staff at RGB TELETEXT RECORD COLOR MIXER RCA Laboratories in 1974. Since then, he CONTROLLER MEMORY MAP SWITCH has worked on a variety of projects, and has received two RCA Laboratories Out- BYTES RGB standing Achievement Awards, one for USER PLPS DISPLAY CRT work on the TK-47 television studio INTERFACE PROCESSOR BIT MAP DISPLAY camera and the other for work on teletext standards. He is now a Fellow of the Technical Staff. Mr. Astle received a B.A. degree in physics, with honors, in 1960, and an M.A. degree in 1964, both from Cambridge University, England. He is chairman and editor of the EIA Drafting Fig. 5. NABTS teletext receiver. This shows a block diagram of a TV receiver with Group that produced the draft EIA NABTS. a built-in NABTS teletext decoder. The teletext decoder takes data from the He is also chairman of the EIA Special Working Group that has responsibility f6r demodulated baseband signal and constructs teletext pages. The signal from the the technical content of the NABTS. He is a teletext page has a wider chroma bandwidth than an NTSC signal, so it drives the member of ANSI committee X3L2 and of its CRT display directly. working group X3L2.1, which has NAPLPS responsibilities. He is also one of the to an increasein the squareness the Color TV Horizon," RCA Engineer, Vol. 24, editors of the NAPLPS. of the corners of TV receivers. No. 6, p. 55-63 (April/May 1979). Contact him at 3. "Petition for Rulemaking of the United Kingdom RCA Laboratories Teletext will also have an impact on Princeton, N.J. regular TV programming. Information re- Teletext Industry Group," FCC RM-3876 (March 1981). TACN ET: 226-2260 porting, where TV video is not required, 4. "Presentation Level Protocol," AT&T (May 1981). may be de-emphasized in regular TV pro- 5. "North American Broadcast Teletext Specification," gramming and made available in teletext. CBS Television Network (June 1981). After the NABTS and NAPLPS are 6. "Broadcast Specification BS -14: Television Broad- 13. J.D. Wetherington, "The Story of PLP," IEEE approved and issued later this year, manu- cast Videotex," Government of Canada, Department Journal on Selected Areas in Communications, Vol. facturers will commit the resources neces- of Communication (June 19, 1981). SAC -1, No. 2, pp. 267-277 (February 1983). 7. "Videotex/Teletext Presentation Level Protocol Syn- 14. W.D. Houghton, "Homefax-A Consumer Infor- sary to achieve an optimized decoder de- tax (North American PLPS)," CSA Preliminary sign. The first generation of decoders may mation System," RCA Engineer, Vol. 16, No. 5, pp. Standard T500, (August 1982). 59-63 (February 1971). be somewhat expensive, butLSI/VLSItech- 8. "Videotex/Teletext Presentation Level Protocol Syn- 15. "Specifications for Safe Action and Safe Title Areas nology should reduce the incremental cost tax (North American PLPS)," ANSI Draft Standard Test Pattern for Television Systems, RP 27.4-1972," of NABTS decoders in television receivers X3.110-982 (June 10, 1983). SMPTE (1972). in much the same way that calculator 9. "Information Procfssing ISO 7 -bit and 8 -bit Coded 16. "Code Extension Techniques for Use with the ISO Character Sets -Code Extension Techniques," ISO costs have declined. 7 -bit Coded Character Set," ISO Standard 2022 Standard 2022 (February 1982). (1973). 10. "Data Processing -Open Systems Interconnection 17. "American National Standard Code for Information Basic Reference Model," ISO Draft Standard 7498 Interchange (ASCII)," ANSI Standard X3.4 (1977). References (February 1982). 18. J. Fleming and W. Frezza, "NAPLPS: A New 1. "FCC Report and Order. Amendment of Parts 2, 11. "Characteristics of Teletext Systems," CCIR Report Standard for Text and Graphics," Byte Magazine, 73, and 76 of the Commission's Rules to Authorize 957 (1982). (February/March/April 1983). the Transmission of Teletext by TV Stations," FCC 12. "Additional Broadcasting Services Using a Televi- 19. L.D. Ryan, "Alphamosaics vs. NAPLPS: The 83-120 (May 1983). sion or Narrow Band Channel," CCIR Report 802- Cost/Performance Trade-off," Videotex '83 Confer- 2. K.M. McKee, "Data Television -A Bright Star on 1 (1982). ence Proceedings, pp. 375-383 (June 27-29, 1983).

Astle. Teletext standards in North America 25 F.J. Marlowe

Technology for digital television

"Every analog process in television will be replaced by a digital process as soon as digital technology for that process becomes economical." -Marlowe's Law of Digital Inevitability

001 1 1 01 1 1 1 00001 1 1 1 0001 1 001 01 1 01 001 1 '001000'000 111 1 000 001 1100 1 1 00. 1 1 000 001 1 1 01 1 1 1 00001 1 1

'11'0 0 '1;0 )111 311 001 141:Jllieb1-10,00 001 1 1 01 1 1 1 00001 1 1 1 0001 1 001 01 1 01 001

Abstract: After reviewing the reasons for Digital signal processing, which has pro- digital addressing of descramblers, and dig- the growth of digital technology's use in duced profound changes in our lives ital microcomputers controlling broadcast television transmission and reception, the through its uses in computers, is now being cameras and tape recorders. But, these are author gives the basic requirements for applied to television. In this article, we not digital TV. Digital TV refers to the resolution, data density, processing speed will review some of the things that are representation of the television waveform and bandwidth. The new areas driving dig- being done digitally in television, some as a series of discrete digital words (called ital TV development-A/D converters, that are likely to be done in the future, pixels) rather than as a continuous analog semiconductor memory, VLSI, magnetic and the technology developments that have waveform. recording and fiber optics-are described made and will continue to make digital The advantages of digital over analog Next, the author reviews the current status television a reality. processing in television are the same as of digital video processing and prognosti- Digital TV includes more than just the those that led to the use of digital process- cates the future of digital TV. use of digital circuitry in TV equipment. ing in other fields. For example, digital We already have digital large-scale inte- circuits have smaller parts counts because 983 RCA Corporation gration (LSI) in tuners, digital transmission they do not require passive resistors, capaci- Final manuscript received July 11. 1983 Reprint RE -28-5-4 and logic in remote controllers for TV, tors, and coils. Moreover, adjustments for

26 RCA Engineer 28-5 Sept./Oct. 1983 gain, level, bandwidth, and so on, can be eliminated, and performance does not grad- ually degrade as parts age. Software can be used to conveniently test subsystems during and after manufacture, and natural control of digital TV processors by other digital equipment is possible. In addition, computer -aided -design can be applied to digital integrated circuit design, and new functions can be done digitally that could not be done at all in analog. Indeed, the attractiveness of digital processing is so great that one could state a rule of digital inevitability: "Every analog process in television will be replaced by a digital process as soon as digital technology for that process becomes economical." We are currently in the early stages of this Fig.1. A typical 1976 analog -to -digital converter costing $15,000 is shown next to a 1980 converter, which is a fraction of the size and one -twentieth the price. replacement process. Until now, the still - Advanced development by several semiconductor companies, including RCA, is expensive new digital technology has been expected to produce price reductions by another factor of twenty. accepted only in the broadcast studio, where equipment ordinarily is costly. But some instances. There are no digital re- soon digital TV technology will spread to ple of 15 X 106 operations per second. ceivers in use yet, but they are expected to Such speeds are near the limits of today's other commercial and consumer equipment. employ at most eight bits per pixel, with technology, and therefore, require power - seven bits a strong possibility. consuming and expensive circuits. General technology requirements The character of the television signal im- Data density Bandwidth poses severe requirements for digital pro- mssing. Every TV frame contains a tre- The exact amount of data in a single frameThe high data rate of real-time digital tele- mendous amount of visual information and depends on the pixel rate of the digital vision implies a large channel bandwidth each frame is replaced by a new frame processor and on certain for transmission and distribution. Further thirty times per second. From basic televi- However, for estimation purposes, each of extending the above estimates, we find sion considerations certaina priorirequire- the nearly 500 lines in a frame can be that 15 Mbytes per second times 8 bits per ments can be derived for digital TV tech- considered to consist of 1000 pixels. With byte gives a bit rate of 120 Mbits per nology. eight -bit pixels, this corresponds to 0.5 mega- second. For this data rate, a channel band- bytes (Mbytes) of data for a single frame. width of approximately 60 MHz is required, For comparison, this is equal to the entire Resolution or ten times the bandwidth of a standard capacity of a double -sided dual -density TV broadcast channel. Methods exist to The human eye can perceive very subtle 51/4 -inch floppy disc, which is capable of reduce the data rate by sacrificing perfor- differences in brightness and color. A dig- storing a 200 -page novel. Thus, any digital mance (depending on processing complex- ital TV processor must represent each pixel TV process that involves temporary stor- ity), but thereis no way to avoid the with fine -enough resolution (determined by age of all or part of a frame (as many pro- inherently high data rate of live digital TV the number of bits per pixel) so that when cesses do) requires a tremendous amount signals. However, the high cost of channel the picture is displayed, brightness and color of storage capacity. bandwidth for digital TV is partially offset variations appear to be continuous. The because a digital channel requires a lower required number of bits per pixel depends signal-to-noise ratio than an analog chan- on the point, in the long TV distribution Processing speed nel, since the digital data is quantized. chain, where the digital processing occurs. The large amount of data in each TV After leaving the beginning of the chain frame and the rate at which frames are in the program -originating studio, a signal updated imply extremely high data rates. Technology status will be converted between analog and dig- Extending the above estimates, 0.5 Mbytes In spite of the severe requirements, many ital several times, and quantization errors per frame times 30 frames per second new technologies have emerged to permit accumulate along the way. On the other gives a data rate of 15 Mbytes per second. digital TV to be used for selected applica- hand, at the end of the chain (in the Thus, if an operation-such as averaging tions, and promise lo permit itsuse in receiver) where the signal will only be two pixels, or multiplying each pixel by a many more applications. Some of the main converted from analog to digital once, no constant-is to be done in real time, the examples are described here. further quantization errors will be intro- processor must be fast enough to complete duced. Consequently, higher resolution will an entire operation every 66 nanoseconds. be needed for digital TVproductionthan Since digital processors perform complex Analog -to -digital converters for digital TVreception.In studio equip- operations by building up simple basic oper- The first step in a digital processor is the ment, at least eight bits per pixel are em- ations, the required computational rates conversion of the continuous analog TV ployed, with nine or even ten used in for the basic operations could be a multi- waveform to a series of digital words. The

Marlowe: Technology for digital television 27 Several companies, including RCA, have demonstrated experimental recorders with 0.044 this capability. This technology is extremely expensive, and, therefore, its use in consumer TV is not yet foreseen. 003$

Fiber optics 0.024 During the past few years, interest in fiber optics for digital TV has grown. The dis- covery of graded -index fibers with low 1 dB per mile) at 0.014 attenuation (typically 1.2-µm wavelength, laser transmitters, and avalanche diode receivers all point toward 1111 eventual use of fiber for interconnection 1980 '81'82 '83 '84 '85 '86'87'88 between digital -TV components that are up to a few miles apart. An example of such an interconnection might be between Fig. 2.The price per bit of memory of dynamic RAMs has been driven down sharply by each fourfold increase in memory size. By mid -1985, the price per bit of a digital camera head at an outdoor loca- 256K RAMs is expected to drop below that of 64K RAMs(Fortune Magazine,May tion (for example, on a golf course) and a 26, 1983, page 154). remote base station. The lack of convenient mechanical hardware such as connectors, splicers, and taps first commercially available 8 -bit video volved a high -enough production volume has hindered the growth of fiber optics for A/D converter occupied an 8 -inch -high of special circuits to support custom VLSI. Consequently, the only LSI used in digital television use up to now. However, in by 19 -inch -wide rack of equipment. April, 1983, RCA also demonstrated an broadcast equipment has been that devel- Today a converter occupies a single 5 - experimental digital -TV transmission link oped for other purposes. The chief exam- inch by 5 -inch circuit card. Figure 1 shows over a kilometer of optical fiber at the a 1976 converter costing $15,000 along- ple is the 64K RAM mentioned above, which is mainly used in computers. For National Association of Broadcasters Con- side a 1980 converter costing $700. At vention. several hundred dollars each, A/D con- consumer products, however, with high verters are suitable today for commercial volume and required low cost, VLSI, specifically for digital TV, will be mandatory. TV equipment that may cost tens of thou- Status of digital video processing sands of dollars. However, for consumer In fact, some companies have already an- equipment, the cost of an A/D converter nounced experimental VLSI chips to do Digital TV has been in use in broadcast must fall to a few dollars or less. Such certain TV -receiver processes digitally. and teleproduction studios since 1975, per- low-cost devices for consumer products One VLSI that has just been introduced forming important and sometimes dramatic are expected soon, from RCA and from for broadcast TV is the charge -coupled functions. other semiconductor manufacturers. device (CCD) imager. This integrated cir- The first widespread application of dig- cuit is not strictly digital.It produces a ital TV was for time -base correction in waveform composed of a discrete series of helical tape recorders. The long helical track Semiconductor memory pixels that have analog amplitudes. How- length (10 inches), combined with the elas- The ability to store all or part of a TV ever, because the waveform is in the form ticity of the tape, resulted in a timing error frame was first economically achieved by of discrete pixels, the CCD imager is well of up to a few TV lines. A digital buffer of use of the 4K single -chip MOS dynamic suited as a video source for digital process- several TV lines (called a time -base cor- RAM in 1975. Since then, increases by ing. RCA demonstrated an experimental rector) was used to compensate for this factors of four in single -chip memory size CCD broadcast camera at the National timing error, thus making broadcasts using have occurred twice-to 16K and to to- Association of Broadcasters Convention in the helical recorder possible. In current day's 64K. Frame stores based on 4K Las Vegas in April of this year. tape recorders, such as the RCA TR800, dynamic RAMs in 1975 occupied twelve the time -base corrector also corrects drop- large circuit cards. Today, with 64K RAMs, outs by replacing lost signal segments with the same storage fits on a single card. The Magnetic recording information from adjacent lines. next -generation frame store based on 256K A digital tape recorder must handle both The next important digital -TV proces- RAMs will require only 16 memory chips. the enormous amount of data and the sor was the frame synchronizer, which was Figure 2 shows the trend memory cost has very high speed required by digital TV. and still is used to align vertical and hori- followed since 1980. If present trends con- Furthermore, a desirable goal would be zontal framing of incoming TV signals to tinue in the semiconductor density, a sin- that a digital tape recorder use no more a studio reference signal. Like the time - gle -chip frame store will not be far away. tape than the best analog recorder. To base corrector, the frame synchronizer con- achieve a tape usage equal to that of the sists of a digital delay, but the synchronizer industry -standard type -C helical recorder, capacity is an entire frame. The incoming Very large scale integration a digital recorder would need a data den- signal is delayed by up to a frame -time to Up to now, the use of digital processing in sity of 107 bits per square inch and a data align its vertical and horizontal sync with expensive broadcast equipment has not in- rate in excess of 100 Mbits per second. studio sync. Before the introduction of

28 RCA Engineer 28-5 Sept./Oct. 1983 frame synchronizers, the entire studio sync Pr received a Ph.D. in Electrical Engineering had to be adjusted to conform to which- from Rutger's University. In 1963, he joined ever incoming video signal was being broad- RCA Laboratories as a Member of Techni- cal Staff on the Research Training pro- cast. gram. From 1963 to 1978, he worked on a A related item isthe electronic slide variety of projects including liquid crystal store, which can hold one or more still displays, computer terminals, computer pictures. A high-speed frame memory is memories, storage tube displays, television sync generators, two-way cable television, used to buffer the picture being displayed. video disc mastering, and flat -panel televi- Other pictures can be stored on computer sion displays. discs, and transferred to the high-speed In 1978, Dr. Marlowe became Head of memory for real-time display. the Digital Video Research Group. From Still another processor that uses a video 1978 to the present, he has supervised projects in broadcast transmitters, televi- frame storeisthe digital noise reducer. sion cameras and tape recorders, digital This equipment adds the previous frame, video research, cable television and direct - or a combination of previous frames, to broadcast satellites. He currently has a the current frame. Since the picture is highly Frank Marlowe received his Bachelor's dozen U.S. patents. correlated from frame -to -frame and noise Degree in Electrical Engineering from Pratt Contact him at Institute in 1963. In 1965, he received a RCA Laboratories is uncorrelated, this addition increases the Master's Degree in Electrical Engineering Princeton, N.J. signal-to-noise ratio of the picture. from Princeton University, and in 1975, he TACNET: 226-3179 The most dramatic use of digital TV in studios is in real-time picture manipulation. A picture manipulator is essentially a frame store that can be addressed for read- out by a different raster than was used for available. Considerable work by interna- be linked together-that is, they will be write-in. The read raster can be of a dif- tional standardization organizations (dis- connected by digital links instead of by ferent size than the write raster, to produce cussed in detail in other articles in this analog links. The digital TV studio of the a picture compression or magnification, or issue) has been done to prepare for digital future will resemble a vast computer sys- it can be offset at an arbitrary angle to tip recording, which many in the broadcast tem with storage capacity and processing the picture. If the size change is a continu- industry consider likely within the next speeds in excess of those of today's most ously alternating vertical expan- five years. Much work is underway through- advanced computer systems. sion and compression, the picture appears out the world to develop digital TV for As a consumer product, digital TV has to tumble toward or away from the viewer. consumer products, but none has been of- not yet made its debut. The rule of digital If the angular offset varies continuously, fered commercially. inevitability will govern the timing of its the picture appears to rotate in the plane introduction. Soon we can expect digital of the display. Under software control, processing in TV receivers, in descramblers combinations of these operations can be Future directions for cable and direct -broadcasting satellite done together to produce zooming, rotat- Digital TV has established a foothold in receivers, in flat -panel displays, and in novel ing and/or tumbling images. In very sophis- broadcast and teleproduction, although the high -definition television systems. These ticated picture manipulators, a picture can major components of a studio-cameras, new digital products will be characterized be mapped onto cylindrical or spherical switchers, recorders, and distribution-are by levels of performance, compactness, and surfaces of arbitrary and variable dimen- still analog. Because most of the compo- reliability that are unknown today. sions, and multiple images can be super- nents and interfaces are still analog, digital RCA currently has digital research and imposed. Many of these manipulations are components in use today are sometimes development projects underway in every by now familiar to television viewers. called "digital islands in an analog sea." facet of television technology. RCA engi- Digital tape recording for television stu- As more studio components incorporate neers will not merely witness the change dios has been under development for sev- digital processing, the "islands" will become from analog to digital TV-we will create eral years, but so far none is commercially more numerous, and ultimately they will much of it.

Marlowe: Technology for digital television 29 T.M. Gurley 1C.J. Haslett

Component analog video recording for studio applications

Separate recording of the parameters, or "components," necessary to reconstruct a color picture offers significant advantages over "composite" recording, whereby signals representing those parameters simultaneously share the same frequency band.

Abstract:Many technical experts in the television industry view the component analog studio as a stepping stone between today's composite studio and the all -digital studio of tomorrow. A component video format offers advantages such as lower chroma noise in FM transmission and recording channels, ease of manipulation post -production applications, and free- dom from the well-known artifacts associated with composite encoding An industry effort is currently underway to develop video signal standards for the component analog studio. With a background in component analog recording for electronic news gathering (ENG), RCA engineers are now developing a component videotape recorder (VTR) for more demanding studio applications. Such a VTR satisfies the requirement for higher quality in today's increasingly sophisticated television pro- ductions and for emerging alternative Equipment for comparing NTSCand component analog recording. Two compo- forms of program delivery to the home. A nent analog VTRs are on the left, and an NTSC VTR is on the right. The center rack prototype system using a modified one -inch contains signal -generating, switching, and monitoring equipment. helical studio VTR product has been successfully demonstrated to the industry. In this system the luminance and two color - in the late 1970s,many in the television by the Society of Motion Picture and Tele- difference signals are time compressed and industry believed that the all -digital studio, vision Engineers (SMPTE). multiplexed into one active line time, with the digital videotape recorder (digital Many experts now believe that the dig- resulting in a signal that has twice the VTR) atitscenter, would be a reality ital VTR as a practical product is still five normal bandwidth. Recording and repro- within five to seven years. However, tech- to seven years away, and that the all -digi- duction of this signal require wider -band- nological progress has been slower than tal studio may not emerge in this decade. width video circuits and new parameters anticipated, and alternative means for satis- For the network broadcasters and major for the FM channel in the VTR. Through fying some of the user requirements for teleproduction houses who will most likely this effort RCA is maintaining a leader- the digital studio have emerged. Recently, pioneer the component digital studio, com- ship position in the field of component the concept of a component analog studio, ponent analog video is viewed as a step- analog video. centered on a component analog VTR, ping stone from today's composite analog has received much attention-for exam- plant. For smaller broadcasters, the com- alma RCA Corporation ple, a Working Group on Component Ana- ponent analog studio may serve adequately Final manuscript received July 28, 1983. Reprint RE -28-5-5 log Video Standards has been established for many years.

30 RCA Engineer 28-5 Sept/Oct. 1983 Recognizing the growing interest in com- video. All of the information necessary to signal does not contain a color subcarrier, ponent analog video, and convinced of the reconstruct a color picture may be con- the undesirable characteristics associated viability of the component analog VTR as veyed by specifying three parameters. A with subcarrier processing in composite a product, RCA Broadcast Video Systems "component" video system handles signals machines are mitigated. These characteris- has undertaken a program of Research in representing those parameters separately. tics fall into three categories-video perfor- Component Analog Video (RCAV). The In a "composite" system, those signals simul- mance, editing features, and time -base cor- primary goal of this program is the devel- taneously share the same frequency band. rector (TBC) performance. opment of a video recorder to serve the The primary components of a color tele- The video performance of an NTSC needs of the component analog studio. vision system are signals representing the VTR is impaired by differential gain and colors red (R), green (G), and blue (B). differential phase, moire, and color noise. Human vision does not require the full A component VTR cannot create differen- Amoving target for the digital VTR resolution for the color hue and saturation, tial gain and phase since these distortions The "Type C" one -inch helical videotape or chrominance, information that it does are subcarrier amplitude and phase shifts recording format has established a strong for the brightness, or luminance. So, in as a function of luminance level. Moire- foothold in the broadcasting and telepro- comparison with RGB transmission and visible as a wavy, interfering pattern of duction industries since its introduction a recording, a substantial amount of band- lines-is a less significant problem in a half -dozen years ago. It offers higher qual- width can be saved by specifying as com- component VTR. The primary contribu- ity, lower operating and maintenance costs, ponents a full -bandwidth luminance signal tors to moire in a composite machine are and more features than the two-inch quad- (Y) and two narrower -bandwidth color - the subcarrier-related modulation products ruplex format it displaced. Second -genera- difference signals. Each of the color -differ- appearing in playback of the FM signal tion Type C machines, such as the RCA ence signals may be synthesized by sub- that carries the video information on and TR-800,' and continuing improvements in tracting luminance from a color signal; for off tape. performance and features offered by all example, blue minus luminance (B -Y). Color noise is the most visible picture manufacturers, present a moving target to The color system adopted in the United impairment and the predominant limita- the digital VTR. States by the National Television System tion on multiple -generation performance. At the present time, user requirements Committee (NTSC) is a composite system Hence, the reduction in color noise over for digital VTRs cannot be met with the in which the color -difference signals (orange that generated by composite recording is available technology. In the key areas of minus Y, magenta minus Y) modulate two the most significant improvement achieved compatibility with existing systems, editing quadrature-related subcarriers having a fre- by a component VTR. The noise spec- capability, operational features such as pic- quency within the luminance band but trum of the baseband video after FM de- ture -in -shuttle, and cost, analog recording above most of the luminance energy? To modulation rises with frequency in the ap- is now superior. Better picture quality re- minimize crosstalk between luminance and proximate triangular shape shown in Fig. mains a primary advantage of digital record- chrominance, that frequency is further cho- 1. The NTSC color subcarrier and its side - ing. With the picture quality improvement sen such that the predominant energy of bands occupy the high -noise region of this realizable by recording components, how- the subcarrier and its sidebands interleaves spectrum above most of the luminance ever, the moving analog target may be with that of the luminance. energy. Decoding of the color information taking yet another stride ahead. impressed upon the subcarrier translates the higher level of noise to more -visible Why components? lower frequencies. Since, in a component The stepping stone to digital Early digital video standardization efforts recorder, the color information does not were directed toward coding of the com- reside on a subcarrier, it can be recovered Despite the technical advantage of composite video signal. After several years of without translation of the noise spectrum. ponent analog recording over composite in-depth study on a worldwide scale, inter- In the NTSC system, the frame rate and recording, economic considerations could est mounted in component coding. It was subcarrier frequency are related such that limit its acceptance among users recently recognized that separate digital coding of the phase relationship between them repeats upgraded to Type C and those likely to be the luminance and color parts of the video in a two -frame (four -field) sequence. This early converts to digital. The stepping -stone signal provides improved picture quality, requires the VTR to color frame when scenario is reasonable only if the compo- facilitates complex signal processing, and playback starts so that the off -tape sequence nent analog step is not a large one. Oth- eliminates subcarrier-related complications matches that of the studio reference. With erwise many users would prefer to wait in editing and other production operations. no subcarrier, and hence no two -frame for the digital VTR. Thus, the success of a Those same virtues apply to the han- sequence or color -framing requirement, a component analog VTR might well hinge dling of analog video in component form. component VTR can achieve a twofold upon the approach taken in its implemen- Indeed, several advantages over composite improvement in start-up time, which is tation. An approach based upon the Type analog recording sought by potential users important in editing situations. In addition, C format is particularly attractive and has of component digital machines are actu- edit points may be selected in single -frame been the primary thrust of the RCAV ally more a function of component versus increments since preservation of subcarrier effort. composite processing than of digital versus integrity is not a consideration. analog techniques. The elimination of subcarrier from the What are components? recorded signal simplifies the TBC design and improves its performance in several To appreciate the advantages of compo- Why component recording? respects. Residual time -base jitter does not nents, one should understand the distinc- Since a component analog video recorder appear as subcarrier phase fluctuations that tion between component and composite is, essentially, a monochrome VTR whose result in color streaks in the picture from

Gurley/Haslett Component analog video recording for studio applications 31 undesired hue modulation. Drop -out compensation is more effective. Replacement Ampl tude (d B) picture elements need not be selected from those of matching subcarrier phase; this allows elements with closer proximity to Luminance Noise Chrominance Passband Spectrum Passband the lost video to be used. Higher -quality still and slow-motion playback ("moviola") is possible. In such non -real-time modes, a composite TBC must invert the phase of the chrominance subcarrier periodically to restore the proper two -frame sequence. Chrominance bandwidth reduction is an undesired side -effect of the process. In a component TBC, the absence of subcarrier obviates the need for this chrominance inversion.

The NTSC window The band -sharing inherent in the NTSC composite encoding method results in a limitation on picture quality imposed upon signals in going through the "NTSC window." Once encoded, luminance and color cannot be separated cleanly. 3.58 4.20 The most noticeable impairments are (Subcarner) cross -luminance and cross -color. Cross-lu- Frequency (MHz) miriance results from contamination of the decoded luminance signal by high -frequency chrominance detail. It is visible as crawling Fig.1.Relationship between baseband NTSC video and triangular noise spectra, after FM demodulation, showing the high -noise environment of chrominance. dots at sharp color transitions. Cross -color is produced by high -frequency luminance energy that falls within the chrominance passband and is decoded as spurious color. Familiar as the "plaid jacket effect," it is sometimes also referred to as moire because trk of its wavy, rainbow -like appearance. Both of these artifacts can be minimized by the use of a comb filter in the decoder.3 Live Component Camera Analog VTR Undesirable consequences, though, are loss Production of diagonal resolution and an artifact aptly Post Production described as "hanging dots" along horizontal color boundaries.

Special Effects Breaking the window

Component Studio Output Traditionally, origination, assembly, record- Analog VTR ing, and transmission of programming employ NTSC video. In recent years, produc- Live Camera tion special effects, such as chroma key or color matting and picture squeezing and zooming, have come into increasingly wide use. These effects require that the video signal be manipulated in component form. For highest quality, the components should Component Component Analog VTR Analog VTR be obtained before encoding and not derived from composite video. Therefore, these effects cannot be performed well using recorded NTSC material.

The post -production scenario Fig.2.The post -production scenario. Using component video, special effects can be applied to prerecorded or live material with high -quality results notachievable A decrease in the production cost and an using NTSC video. increase in the quality of the end product

32 RCA Engineer 28-5 Sept./Oct. 1983 Film Post Production I Negative

Size Manipulation

Color Correction Fig. 3. The DBS scenario. With an end -to -end component system, high -quality program material could be delivered to the home without the effects of NTSC encoding.

may be achieved by configuring the entire aspect ratio of the home television screen. tured two channels, each having 15 -MHz studio to handle the signal in its compo- Use of a component analog VTR permits video bandwidth. A future broadcast appli- nent form. As Fig. 2 suggests, special effects any post -production work, such as addi- cation was conceived, whereby a wide - may then be applied at any point to either tion of titles or creation of trailers, to be band luminance signal would be recorded recorded or live material. The signal need done off -tape rather than by repeated han- on one channel, while two frequency -divi- pass through the NTSC window only once- dling of the delicate negative. sion -multiplexed color -difference signals, at the broadcast transmitter. Until recently, Transmission of the completed program of narrower bandwidth, were recorded on the non -availability of cost-effective com- may require conversion between a com- the other. ponent recorders and the efficiency of "single - ponent analog format optimized for studio A technique of time compression and wire" handling of the NTSC signal, over applications and a MAC -like transmission time -division multiplexing of components "three -wire" distribution of components, format, which could involve alternate -line was developed at RCA Laboratories in have precluded interest in such component chrominance. The NTSC window need early 1980., For demonstration, two com- studios. Both of these factors were consid- not be applied until the signal has reached pressed color -difference signals were sequen- erations in the development of the RCAV the indoor unit in the subscriber's home. tially multiplexed onto one channel of a signal format. A conventional television receiver will re- two -channel VTR, with luminance being quire NTSC video, either baseband or mod- recorded on the other channel. Extension ulated onto an unused rf channel. How- of this approach, to permit multiplexing of The DBS scenario ever, recently introduced models also can all three components on a single channel, New forms of program delivery to the accept RGB component video inputs that is the basis of the RCAV technique. home need not be constrained to NTSC bypass the set's NTSC decoder. Ultimately, In 1981, RCA Broadcast Video Sys- transmission. In particular, direct broadcast- then, the signal would never pass through tems introduced the Hawkeye recording ing by satellite (DBS) will probably use NTSC encoding and decoding from the camera system for Electronic News Gath- component transmission.In the United telecine to the home screen. ering (ENG) applications.6 Using a format Kingdom, a technique known as MAC, called Chroma Trak, Hawkeye records for Multiplexed Analog Components, has analog components on half -inch tape cas- RCA experience been adopted recently for DBS service. settes. Accessories developed for the Hawk - Companies planning such service in this in component recording eye system are now permitting users to country are looking favorably upon a MAC - Developments in component analog record- exploit fully the advantages of component like technique for use here. ing have been made by several groups at recording by implementing total compo- Figure 3 illustrates a possible DBS sce- RCA over the past decade. Individuals nent editing suites for their ENG opera- nario. For airing of feature film material, a involved with this previous work are among tions. high -quality negative is transferred to tape, the contributors to the RCAV program. via a telecine having component analog A wideband recording system called video (CAV) outputs and a processor for ADVISOR was produced by RCA Govern- Which components? color correction and geometric manipula- ment Communications Systems for airborne In the international deliberations that led tion to ensure that relevant scene action instrumentation applications.4 Using quad- to the 1982 adoption of CCIR Recom- from the wide-screen film is not lost to the ruplex recording, the ADVISOR 152B fea- mendation 601, "Encoding Parameters of

Gurley/ HaslettComponent analog video recording for studio applications 33 RCA demonstrates technical leadership

The RCAV component analog studio VTR was first shown to the broadcasting industry at the Na- tional Association of Broad- casters Convention, held in Las Vegas, Nevada in April 1983. Dur- ing a four -day period, some one - thousand people were invited to a private RCA suite to witness side - by -side comparisons of standard NTSC and component analog playbacks. A marked reduction in color noise and complete absence of the NTSC artifacts of moire and dot crawl in the com- Authors Haslett and Gurley point out differences between NTSC and component ponent video were pointed out in analog VTR playbacks of material recorded simultaneously from the same a variety of recorded scenes that sources. included high -resolution pictorial material, test charts, and the obli- potential users representing bility and not as a product intro- gatory plaid jacket. broadcasting, teleproduction, and duction, the developmental VTR International technical experts DBS interests viewed the RCAV was regarded by observers as currently involved in setting sig- demonstration. Presented as a proof of RCA leadership in this nal format standards as well as statement of technological feasi- emerging field.

Digital Television for Studios," Y, R -Y, The technique chosen for RCAV is sim- Y R -Y -v- B -Y andB -Y were chosen as the components ilar to the MAC concept in that compo- 100- to be encoded. With the digital video stan- nents are time -compressed and multiplexed dardization work as a precedent, and the into one TV line. The compression is great- 50- _r - goal of having the component analog stu- er, however, so that both color -difference dio maximally compatible with the future signals can be transmitted along with the 0- _r evolution of the digital studio, the decision luminance for each line. Since the band- was made to use Y/R-Y/B-Y components widths specified for Y, R -Y, and B -Y are -40- - for RCAV. It was further decided to main- in the ratio 4:2:2, the compression ratio is One TV Line tain the same bandwidth for each compo- 2:4:4. That is, the luminance signal is com- Fig. 4. The RCAV signal format. A 100 - nent as proposed by the CCIR. The lumi- pressed to occupy half the line, and each percent -saturated color -bar test signal nance channel is, thus, specified to be flat of the color -difference signals is compressed illustrates the time compression and to 5.5 MHz, and each of the two color -dif- to occupy one-fourth of the line. The re- multiplexing of Y, R -Y, and B -Y com- ference channels is to be flat to 2.75 MHz. quired channel bandwidth, then, is 11 MHz ponents within one TV line. for the specified luminance bandwidth of 5.5 MHz. R -Y andB -Y are scaled so that, with The RCAV format Figure 4 depicts the RCAV format. The allowance for headroom, their maximum The MAC satellite transmission system em- waveform shown represents a color -bar excursions are the same as the excursion ploys time compression of the components test signal of 100 -percent saturation. The of Y. Each of the color -difference signals in order to multiplex the luminance signal luminance signal occupies the first half of is preceded by an interval of 50 -percent - and one color -difference signal within the the TV line. The horizontal blanking inter- level pedestal to permit clamping to re- time of one TV line. The compression val is considered part of luminance for this store proper black balance upon demulti- ratio was chosen to be inverse to the band- format, so the horizontal sync pulse and its plexing of the RCAV signal. width ratio of the components to use most front and back porches (blanking levels To obviate the need for modification of efficiently the available channel bandwidth. that immediately precede and follow the vertical sync separation circuitry, the RCAV The two color -difference signals are trans- sync pulse) are all compressed two -to -one. signal retains standard equalizing and ser- mitted on alternate lines. Thus, the vertical Since the color -difference signals are bipo- rated vertical sync pulses. However, some resolution for chrominance is half that for lar, they are placed upon a 50 -percent - advantages can be seen in changing the luminance. This compromise for the sake level pedestal with respect to the black -to - vertical sync format. Current investigations of conserving transponder bandwidth is white range of the luminance signal. The into this, and other aspects of the RCAV subjectively acceptable for home viewing. R -Y component occupies the third quarter signal format, will lead to recommenda- For studio use, however, full vertical chro- of the line, while the WY component occu- tions for eventual standardization and incor- minance resolution is desirable. pies the fourth quarter. The amplitudes of poration into products.

34 RCA Engineer 28-5 Sept./Oct. 1983 RCAV recording considerations bing," noise. Scraping noise is induced in these unwanted frequencies fall within the For recording purposes, the RCAV signal the head winding by the magnetostrictive video passband. Raising the carrier fre- may be regarded as a standard mono- property of ferrite heads under deforma- quency moves the higher -amplitude spu- chrome TV signal that has a greater band- tion from tape contact. Development of rious components out of band. width and a narrower horizontal blanking tapes with smoother surfaces and smaller In a VTR that is recording a composite interval. It follows then that one approach magnetic domains of more uniform orien- video signal, the predominant cause of moire is the presence of the high-energy, to recording the signalisto modify a tation will reduce tape -related noise. Further standard VTR to cope with those signal improvements in noise performance will high -frequency subcarrier and its sidebands characteristics that are unique. Maintain- result from development of heads with in the modulating signal. Hence, in that ing the features of modern studio VTRs higher magnetic efficiency and lower sen- situation, subcarrier is an important con- suggests starting with a current Type C sitivity to rubbing effects. sideration in the selection of carrier fre- studio VTR product. Then, the primary Losses from physical properties of the quency and level of high -frequency pre - emphasis. Since the RCAV signal contains considerationisachieving the required tape and head -to -tape separation are the video channel bandwidth of 11 MHz with primary contributors to the degradation of no subcarrier, more flexibility in the selec- a machine designed for a 4.2 -MHz video SNR when the FM channel is widened tion of these parameters and an improved channel. and the head -to -tape writing speed is un- level of moire performance are possible. Recording a greater bandwidth video changed. The increase in carrier and side - signal mandates changes in the values of band frequencies means that shorter wave- certain VTR parameters. However, to facil- lengths are recorded on tape. This results An RCAV recorder implementation itate retention of features such as variable in fewer magnetic domains per wavelength Based on the foregoing considerations, the play speeds, picture -in -shuttle, and confi- and closer opposing magnetic fields within best approach for widebanding a VTR to dence playback during record, it is unde- the tape. These factors increase demagne- record the RCAV signal is to raise the car- sirable to alter scanner speed, tape speed, tization effects that decrease the signal level rier, to prevent "folded sidebands" and and head -to -tape writing speed from their preserved. The level of the signal that can minimize moire, and to increase carrier original specifications. Therefore, the burden be recovered is further reduced since head - deviation to improve SNR. However, lim- for change rests on the video/FM channel to -tape separation loss on playback is in- iting the SNR improvement is the dimin- itself. Since the video bandwidth has been versely proportional to recorded wave- ishing carrier -to -noise ratio at higher re- established, the optimum FM parameter length. These effects lower the carrier level corded frequencies. Following this ap- values depend largely on the required sig- and hence the carrier -to -noise ratio avail- proach, RCA engineers modified an RCA nal-to-noise ratio (SNR) and the tolerable able on playback. Reduction in SNR of TR-800 Type C studio recorder and a level of spurious signals the demodulated video follows directly. TBC-8000 digital time -base corrector to Current research into the various tradeoffs The FM demodulation process translates record and reproduce the RCAV signal. parallels the investigations done previously the relatively flat channel noise spectrum The FM modulator was adapted to oper- to develop the high -band quadruplex and into a baseband spectrum that has increas- ate with a higher carrier frequency and Type C FM standards.' In addition, other ing noise power with frequency. There- deviation range, and the FM channel elec- techniques are being employed, such as fore, rapidly decreasing SNR results from tronics were widebanded. Scaling of var- computer modeling of the FM channel the increasingly higher noise levels encoun- ious filters was necessary, primarily the using programs originally developed for tered as the video bandwidth is raised. linear roll -off filter that precedes the lim- the study of FM transmission via satellite. The most direct approach to combat iter and the demodulator output filter. Mag- The almost threefold increase in video SNR loss is to allow wider deviation of netic heads with narrower gaps were fab- bandwidth necessary to handle the RCAV the FM carrier with consequently higher ricated to resolve the shorter recorded wave- signal requires a commensurate increase in signal output from the demodulator. An lengthsduring playback. The playback the FM bandwidth. There is a direct in- effective approach to reduce demodulated equalizer was redesigned to, correct the crease in the bandwidth of the first -order high -frequency noise isto pre -emphasize frequency characteristics of the larger -band- FM sidebands resulting from the greater the higher frequencies in the video signal width playback channel. bandwidth of the modulating video signal. before modulation and attenuate all high In the video domain, evaluation and This, in turn, requires that the lowest car- frequencies after demodulation. Both lin- some redesign of amplifiers in the input, rier frequency be raised to prevent any first - ear and nonlinear techniques may be ap- output, and monitoring paths were neces- order lower sideband from extending below plied. sary to ensure flat frequency response to zero frequency and creating a "folded side - 11 MHzwithout significant distortion. All band" at the corresponding positive fre- video clamp circuits required adjustment quency. Moire to operate inside the narrower back -porch The limiting effects of the tape and the in- interval. Pulse -processing circuits required tentional limiting applied prior to demodu- adaptation to separate accurately the nar- Signal-to-noise ratio lation unavoidably create harmonics of the rower RCAV horizontal sync pulses and Widebanding the VTR, while maintaining carrier and its sidebands. Demodulation of thus maintain proper timing references for an acceptable SNR, is a formidable chal- the third -harmonic lower sidebands pro- various servo systems. lenge. The primary sources of noise in duces primary spurious frequency compo- The companion digital time -base cor- magnetic recording are the tape itself, the nents whose number and strength depend rector also required modifications to accom- magnetic heads, and the dynamics of head - upon the carrier location and the frequency modate the playback RCAV signal. As in to -tape contact. The dynamics resultin and amplitude of the modulating signal. the VTR, analog video circuits were altered separation losses and "scraping," or "rub- Moire is the visual effect created when for wider bandwidth and proper clamping

Gurley/Haslett: Component analog video recording for studio applications 35 taneous independent signals, Y, R -Y, and B -Y. A second matrix, the inverse of the first, develops RGB components that are TK-47 G Matrix R -Y then displayed on a standard RGB picture Camera B B -Y monitor.

Although not parts of the VTR proper, Record the compressor and expander are vital to the demonstration system as interface between existing RGB studio equipment and the RCAV signal. In the compressor, the incoming Y, R -Y, and B -Y components RCAV R -Y are low-pass filtered, digitized by A/D TBC Expander Matrix converters, and written into individual Y, B -Y B Monitor R -Y, and B -Y memories during one TV line time. Each memory is two TV lines Playback long to ensure enough data storage loca- Fig. 5. Major elements of the demonstration system for recording and playing back tions for the incoming line while the pre- the RCAV signal. vious line is being compressed. During the first half of the next TV line, Y is read out of its memory at twice the writing speed. This effectively compresses it to one-half line time and doubles its bandwidth. Dur- ing the third and fourth quarters of the line, R -Y and B -Y, respectively, are read out of their memories at four times the writing speed, effectively compressing them COMPONENT to one -quarter line time and quadrupling ANALOG VTR their bandwidths. The resulting data are converted to an analog signal by a single D/A converter, and filtered to eliminate the clock frequency. The expander performs the inverse function of restoring the compressed Y, R -Y, RGB TO and B -Y signals to their original real-time Y/R-Y/B-Y relationships. Since the expansion process MATRIX EXPANDER AND and the preceding time -hasp correction pro- Y/R-Y/B-Y TO cess are both digital, the RCAV signal is RGB MATRIX COMPRESSOR passed directly from the TBC to the expander in digital form. This, then, eliminates a D/A stage with filtering in the TBC TBC and an A/D stage with filtering in the expander. As the expander receives the RCAV data, the first half of each TV line is written into a Y memory, the third quarter of the line is written into an R -Y memory, Fig.6. RCAV demonstration hardware. Thekey pieces of equipment indicated are and the last quarter of the line is written interconnected as shown in Fig. 5. into a B -Y memory. As in the compressor, each memory is two TV lines long to pro- and sync separation. The analog -to -digital Fig. 5 and pictured in Fig. 6. An RCA vide sufficient storage for the next incom- (A/D) converter, memory, and digital -to - TK-47 studio color television camera is ing TV line while the present line is being analog (D/A) converter clocks were raised the source of video for the demonstration. expanded. During the next TV line, data in frequency, and the anti-aliasing and clock A simple matrix circuit transforms the RGB are read out of the luminance memory at rejection filters were scaled. The memory signals from the camera into Y, R -Y, and half the writing speed and out of the color - was reorganized to handle the higher clock B -Y. Horizontal and vertical sync are added difference memories at one-fourth the writ- frequency and a greater number of sam- to Y at this point. These signals are ap- ing speed. This expands each component ples per line. plied to a digital compressor that converts back to a length of one TV line. them into the RCAV format. This signal By starting the reading of all three memo- then becomes the VTR input. ries together, the correct registration of Y, A demonstration system The VTR plays back the RCAV signal R -Y, and B -Y for each line is obtained. The hardware assembled to demonstrate through the TBC to remove timing errors. These signals are then D/A converted and the recording and reproduction of the A digital expander then converts the out- low-pass filtered to provide analog wave- RCAV signal format is diagrammed in put RCAV signal back into the three simul- forms. A sharp cut-off ellipticalfilteris

36 RCA Engineer 28-5 Sept./Oct. 1983 used for Y. Slower roll -off Gaussian filters are used for R -Y and B -Y, since ringing is subjectively more disturbing on color transitions. To ensure black balance, R -Y and B -Y are clamped during their 50 -percent - pedestal intervals. Ideally, compression should be done by each video source, which would originate an RCAV, or similar, signal for distribution in the studio. Expansion would be required only for display purposes. All inter- vening elements of the system, including recorders, would accept and deliver the compressed signal. Availability of such a component VTR will spur development of compatible switchers, effects devices, and Tom Gurley is Unit Manager, Tape Carl Haslett is a Senior Member of the Advanced Development Engineering, Engineering Staff, Tape Advanced Devel- other system elements that will make pos- Broadcast Video Systems, and recently opment, Broadcast Video Systems. He sible the "single -wire" component analog has been associated with the TR-800, joined RCA in 1980 after receiving bache- studio. Hawkeye, Digital VTR, and RCAV pro- lor's and master's degrees in electrical grams. With RCA since 1970, he was engineering from Lehigh University in 1977 involved in television systems engineering, and 1980, respectively. Currently involved RCA's industry position studio automation, and digital video prod- in the RCAV project, he previously held uct development. His professional expe- assignments on the TR-800, Hawkeye, and RCA has been an active participant in the rience in the broadcasting industry spans Digital VTR programs. His association with digital video standardization effort during more than eighteen years. He has been the broadcasting industry spans nine the past nine years, playing a leading role active in digital video standardization and years, including college radio and televi- is currently Secretary of the SMPTE Work- sion activities as well as commercial in the discussions and demonstrations that ing Group on Component Analog Video broadcast engineering experience. He is a resulted in the adoption of worldwide stan- Standards and a member of its Sub -Group member of SMPTE, Eta Kappa Nu, and Tau dards embodied in CCIR Recommenda- on System Design. A Duke University Beta Pi. tion 601. That position of industry leader- graduate, he earned an MSE in EE from Contact him at ship is continuing as technical experts de- the University of Pennsylvania. He holds RCA Broadcast Video Systems two patents and memberships in SMPTE, Camden, N.J. bate the issues of component analog video IEEE, Eta Kappa Nu, and Tau Beta Pi. TACNET: 222-4742 standardization. RCA is a major contribu- Contact him at: tor to the efforts of the SMPTE Working RCA Broadcast Video Systems Group on Component Analog Video Stan- Camden, N.J. dards and its sub -groups. TACN ET: 2 2 2 -364 9 First to demonstrate a studio -quality component analog VTR, baced on the Type C format, at the 1983 National Association of Broadcasters Convention, RCA is con- veying an image of technical leadership to References the user community. Such demonstrations ing Systems,"RCA Engineer,Vol. 19, No. 4, p. 67 of progress and discussions with key poten- I.L. V. Hedlund, "RCA's TR-800 Helical VTR: A (December 1973/January 1974). tial users, concerning their requirements, Computer -Based Total System Design,"RCA Engi- 5. R. A. Dischert and R. E. Flory, "Transmission Sys- combine with ongoing engineering research neer,Vol. 26, No. 7, p. 53 (July/August 1981). tem with Sequential Time -Compressed Baseband Col- to provide direction to RCA's industry 2. D. H. Pritchard and J. J. Gibson, "Worldwide Color or," U. S. Patent No. 4, 376, 957 (March 15, 1983). participation. TV Standards-Similarities and Differences,"RCA 6. S. L. Bendell, L. J. Bazin, and J. J. Clarke, "The Engineer,Vol. 25, No. 5, p. 63 (February/March Hawkeye Camera,"RCA Engineer,Vol. 27, No. 4, The goal of all of these efforts is to 1980). ensure that RCA iswell positioned to p. 18 (July/August 1982). 3. D. H. Pritchard, "Color TV Picture Enhancement 7. K. Sadashige and J. B. Van Anda, "Spectrum Anal- manufacture and market a component with a CCD Comb Filter,"RCA Engineer,Vol. 25, ysis of Magnetic Video Recorder FM System,"RCA analog studio VTR whenever industry stan- No. 6, p. 6 (April/May/June 1980). Engineer,Vol. 13, No. 5, p. 42 (February/March dards are set. 4. J. S. Griffin, "Recent Advances in Wideband Record- 1968).

Gurley/Haslett: Component analog video recording for studio applications 37 G.A.Reitmeier

Digital videotape recorders: Tape format and error -concealment considerations

An appropriate combination of tape format and error - concealment techniques can provide a highly "transparent" digital videotape recorder (DVTR) without the need for complex error -correcting codes.

The potential advantages of digital videotaperecording present device. The only problems will be bit errors resulting from drop- some of the strongest incentives to implement and make wide- outs caused by surface imperfections in the tape, which can spread use of digital television standards in the broadcasting and result in burst errors affecting as much as one quarter of a televi- teleproduction industry. Analog recording of the NTSC (National sion line worth of data. The same problem occurs in analog Television System Committee) signal is currently the greatest VTRs, where the dropout is concealed by averaging the video limiting factor in achieving ultra -high -quality television pictures on adjacent scan lines, with the proper weighting to correctly in the studio, and is likely to remain so. accommodate the line -to -line subcarrier phase reversal of NTSC. Although much industry activity is devoted to (time-) multi- By selecting a tape format that has an appropriate error pattern plexed analog component (MAC) television signals,' 2 which in response to a dropout, it becomes possible to use much more slightly increase the chrominance bandwidth and eliminate NTSC sophisticated error concealment in a DVTR. artifacts, digital recording remains vastly superior. In any analog - Althoughitispossible to design complex error -correcting recording technique, each successive recording further degrades codes having long burst -error -correcting capability, there are sev- the quality of the television signal, introducing both nonlineari- eral problems in applying these techniques to DVTRs. First, the ties and noise. A television program typically goes through eight burst -error length that must be corrected is very long, demanding to ten re -recordings in the process of post -production and distri- a long code block that requires many computations at very high bution, and considerable time and effortis spent developing speed. Secondly, since this function is a record -side process, the judicious editing sequences to conserve the number of re -record- required coding hardware must be included even in a portable ings. Therefore, the transparency and quality of the videotape recorder, which places severe constraints on size, weight, and recorder is of great importance to the industry. power. On the other hand, error concealment is a replay -side Since a digital videotape recorder (DVTR) will record the process, which means that concealment hardware need only be 4:2:2 digital studio standard,3.4 it will have outstanding picture present in a studio recorder that plays back tapes made on a quality; and since digital information is highly insensitive to non- portable recorder. And finally, the probability notwithstanding, linearities and noise, the DVTR will be essentially a transparent any error -correcting code will occasionally fail, resulting in catas- trophic errors that must be concealed. Therefore, the purpose of this paper is to discuss DVTR recording formats and error -con- Abstract:Digital videotape recorders (DVTRs) could give cealment techniques that can provide the high performance greatly increased quality and "transparency." Burst errors result- required in a DVTR, without the use of complex coding tech- ing from tape dropouts are the biggest obstacle to a fully trans- niques. parent recorder. An appropriate tape format can shuffle the data, arranging it so that a burst error in the data results in a pattern of single -pixel errors in the television picture. Digital signal -pro- Tape formats cessing techniques can then provide error concealment with an The design of a recording format for a DVTR involves a com- extremely high level of quality. Thus, the proper combination of plex set of tradeoffs in both mechanical and electrical character- tape format and error concealment can provide a highly trans- istics, which greatly impact the performance of the machine.5 parent DVTR without the use of complex error -correcting codes. Although these issues are far too complex to fully address here, it is possible to isolate and discuss some of the electrical character- ©1983 RCA Corporation Final manuscript received July 29, 1983. istics that relate to error management. Itis certain that the Reprint RE -28-5-6 DVTR willuse helical -scan recording consisting of multiple

38 RCA Engineer 28-5 Sept./Oct. 1983 TWO PARALLEL TRACKS

Fig.1.Tapeformat for a digital videotape recorder consisting of two parallel tracks, with a two-line track offset delay, each track alternately recording odd and even pixels from each television line. parallel tracks (probably two) to record the 4:2:2 digital video standard. Indeed, the DVTR can eliminate the effects of tape YI 0 03 0 Y5 ® Y7 1C -i3) Y9 ® Oil ® YI3 dropouts by error -concealment techniques alone. This results 111 V1 0 0 U303 0 0 u5v, 0 ® from the fact that, unlike an analog recorder, a DVTR need not record data that is adjacent on the television raster on adjacent positions on the tape. The digital data may easily be rearranged, YI Y2 ® Y4 ® YR YK 0 Y10 ;2 or "shuffled," so that even a large burst error will not affect more than one pixel within a spatially adjacent "neighborhood" on the ® 0 u2 v2SON 04 SS06 vs 8 television raster. Furthermore, this shuffling may be accomplished with relatively simple circuitry consisting of delay lines and switches; no complex framestore is required. ; 0 Y3 ® Y5 0 07 0 Y9 ® ;3 Consider the arrangement shown in Fig. 1. The odd pixels (of 01 ® U3 V3 0 V5Vs ® U7 both luminance and color -difference signals) from the odd scan lines and the even pixels from the even scan lines are recorded Fig. 2. Error pattern resulting from the loss of an entire track on track 1, while the remaining pixels are recorded on track 2. in the tape format of Fig. 1. The circled samples are errone- Even if an entire track containing half the data is lost, this ar- ous. Note that each erroneous sample has valid pixels of rangement results in an error pattern that is a "checkerboard," the same component that are horizontally and vertically shown in Fig. 2, where an erroneous pixel is surrounded by adjacent. valid pixels from which it can be reconstructed. Furthermore, a two-line "track -offset delay" is inserted between tracks 1 and 2 The tape format shown in Fig. 1 (or one similar to it) is easily in Fig. 1, so that in the event of a short simultaneous loss of both implemented but, because of the data organization, transforms tracks, as would be caused by a longitudinal scratch on the tape, burst errors resulting from tape dropouts to checkerboard -pat- two different checkerboard error patterns occur, separated on the terned single -pixel errors in the television signal, which can be television raster by the amount of the delay. concealed with much better accuracy than a continuous error. The track -offset delay is a function of the maximum expected dropout length, which is typically one fourth of a line, and other data -blocking constraints (such as those required to achieve an Error detection acceptable range of variable -speed replay). Therefore, this delay Now that we have established an approach for the DVTR tape must be chosen so that neither an along -track nor a longitudinal format that produces acceptable error patterns, we might also defect results in the loss of horizontally or vertically adjacent briefly discuss how an error might be detected so that error con- information. This delay may be either electrical or mechanical cealment can be activated. Perhaps the simplest and oldest and is clearly a minor addition to the DVTR hardware, espe- method of error detection is to detect a loss of signal amplitude. cially considering that it makes possible the use of sophisticated In a DVTR, it is also likely that some form of channel coding error -concealment techniques under the most severe conditions. will be used, which transforms the serialized bit stream resulting

Reitmeier: Digital videotape recorders: Tape format and error -concealment considerations 39 P(x,y) = ( I / 16)p(x-I, .1-I) + (3/ 16)p(x0-1) DIGITAL VIDEO ± (1 / 16)p(x-F1, J-1) -1- (3/ 16)p(x-1, 1.)

(WITH8 ERRORS) + (3/ 16)p(x+1, y) + (1 / 16)p(x-1, y+1) + (3/ 16)p(xj+1) + (1 / 16)p(x+1, y+1) wherep(x,y)represents the pixel value at location (x,y) on the television raster. - DIGITAL This estimator can be implemented for the luminance channel VIDEO IWITH as shown in Fig. 3. Two1Hdelay lines provide access to three x ERRORS CONCEALED) adjacent scan lines on the television raster, while the two pixel delays on each tap of the vertical delay line provide access to three pixels. Thus, this delay -line structure provides access to the 3 X 3 spatial neighborhood required by the linear estimator. The line delays can be implemented with RAM and a line -length ERROR FLAG counter, while the pixel delays are simply latches. A network of three adders provides the sum of the four pixels, which are diag- Fig. 3. Linear estimator for the luminance channel. onally adjacent to the center pixel, and the output can be simply shifted to the right by four bits to multiply the result by the from the pulse -code -modulated (PCM) coding into a form more factor of1/16. suitable for recording on magnetic tape. A similar network adds the four pixels, which are horizontally Many such codes have been proposed, all having their own and vertically adjacent to the center pixel, and this output is used virtues.6 Some channel codes contain no dc component, and are to address a read-only memory (ROM), whose contents contain thus easily passed through the rotary transformer located in the the address times the factor3/16.One final adder produces the headwheel, while other codes contain certain invalid sequences estimate p(x,y), which is input to a multiplexor along with the of transitions, which can be used for error -detection purposes. By center pixelp(x,y).The multiplexor is controlled by an error flag this last method, even if some errors go undetected, certainly delayed by another bit plane to match the delay of the center enough errors could be detected to define the occurrence of a pixelp(x,y),so that when an error occurs, the estimate is substi- dropout and to activate concealment mechanisms. Finally, the tuted for the erroneous pixel. use of error -detecting source codes is well known, and these A similar system can be implemented to time -multiplex the codes can be relatively simple, since only error detection (and two chrominance signals and provide error concealment with not correction) is required. hardware operating at the same speed as that of the luminance In a high-performance DVTR, it is desirable to combine all of concealer, differing slightly in the delay -line structure, to account these detection techniques, to provide a high level of confidence for the multiplexing. that no error will slip through undetected and thus unconcealed. The use of two-dimensional linear estimators offers a substan- Perhaps the most powerful balance of error -management strate- tial improvement over the simple vertical estimators used in gies is to combine very simple error -correcting source codes, analog recorders, since they take advantage of redundancy in all which are intended to handle random bit -errors, with sophisti- directions of the image. Linear estimators, however, suffer from cated error -concealment techniques, which are intended to han- performance problems because of the Nyquist criterion and can dle tape dropouts. With this in mind, let us discuss the error - introduce artifacts on sharp edges and regions containing much concealment techniques themselves. high -frequency energy, which are subjectively very important to picture quality. Consider the use of the above estimator on a picture where Error concealment the top scan line is black, and the middle and bottom ones are Consider the error pattern shown in Fig. 2, where the circled white. The estimate for an erroneous pixel on the middle line samples represent erroneous pixels. Note that each erroneous would be5/16black and 11/16 white, resulting in a gray pixel pixel is surrounded by a pattern of spatially adjacent pixels of rather than a white one. In the case where both top and bottom the same component (Y, U or V). In the previously discussed lines are black and the middle one white, an estimate for an case of dropout compensation in analog VTRs, only information erroneous pixel would be10/16black and6/16white, resulting in from adjacent scan lines is available to form an estimate. a dark -gray pixel. In the presence of a dropout affecting a large The chief virtue of data shuffling in the DVTR recording portion of data there are many such artifacts, and they occur in a format is that the error pattern resulting from a dropout contains pattern, which makes them more noticeable and objectionable a pattern of horizontally, vertically, and diagonally adjacent pix- than that of a truly isolated single -pixel error, although it is con- els that can be used to conceal the erroneous pixel. A linear siderably better than the concentrated error that would result if estimate for the erroneous sample can be formed by computing no shuffling were used in the recording format. a linear combination of the spatially adjacent pixels, and the Figure 4 illustrates a picture containing a large number of erroneous pixel is concealed simply by substituting the estimate simulated dropouts, only one of which might occur every ten for the actual pixel when indicated by an error flag (derived by seconds in a poorly performing DVTR. The results of perform- the methods previously discussed). One example of a linear ing error concealment using the linear estimator are shown in estimator is a weighted average consisting of3/16times each of Fig. 5, and although most of the errors are removed, some arti- the four pixels that are horizontally and vertically adjacent and facts are clearly visible. Although most error concealment arti- 1/16times each of the four pixels that are diagonally adjacent facts happen "on the fly" in a continuous replay, and are not within a 3 X 3 cell centered at the erroneous pixel. The linear frozen for close scrutiny, DVTRs will often be called on to pro- estimate p(x,y) is thus vide "freeze-frame" replay as a special effect. More important,

40 RCA Engineer 28-5 Sept./Oct. 1983 Fig. 4. Picture containing simulated dropouts, as illustrated Fig. 5. The results of error concealment by use of the linear in Fig. 2. estimator. Artifacts are visible on edges, particularly in the high -frequency wedge. the cascading of dropout errors, when making multiple genera- tions of tape recordings, means that error concealment of extremely high quality is desired, and this level of quality cannot be provided by linear estimators. DIGITAL Perhaps one of the greatest potential advantages of digital sig- VIDEO L-PA 11,y (WITH nal processing is the ability of digital circuits to make decisions ERRORS) and perform appropriate actions, thus "adapting" themselves to the input signal. To address the edge -response limitation of linear DIGITAL estimators, consider the possibility of switching between horizon- 11 VIDEO ERRORS tal and vertical estimates based on some criterion supplied by the CONCEALED) spatially adjacent pixels.

One such technique is the so-called "minimum -difference" P (x,y) algorithm, which can be described as follows. First, the absolute IH value of the difference between the pixels to the left and right of the erroneous pixel is computed, and the same computation is performed for the pixels above and below the erroneous pixel. ERROR IH Then, whichever pair has the minimum difference will be aver- FLAG aged and used as the estimate. A block diagram of this system for the luminance channel is shown in Fig. 6. A delay line similar to that in Fig. 4 provides access to the required spatial Fig. 6. Minimum -difference adaptive estimator for the lumi- neighborhood. A subtractor computes the difference between the nance channeL pixels to the left and right of the erroneous pixel, and the absolute value of this difference is found. This may be achieved by plification is based on the reasonable assumption that the lumi- use of a ROM, or by performing a 2's complement inversion nance and chrominance resolution will be in the same direction. (invert and add one) if the difference is negative. Complement The minimum -difference technique works quite well on hori- inversion requires the rise of XNOR gates and an adder. The zontal and vertical edges. Consider the example of a vertical same network is used to compute the absolute difference of the edge consisting of a black -to -white transition, where the errone- pixels above and below the erroneous pixel, and both absolute ous pixel was originally white. The horizontal pair will have a differences are input to a digital comparator, whose output con- large difference (since one is white, and the other is black), while trols a multiplexor to select between a horizontal averagePH the vertical pair will have a small difference (since both are (x,y)and a vertical averagePv (x,y)provided by the respective white), and hence, the vertical pair will be averaged and used to adders. A final multiplexor is controlled by a delayed error flag replace the erroneous pixel, correctly resulting in a white esti- to substitute the minimum difference estimate p^A(x,y)for the mate. Had a similar situation existed for a horizontal edge, a center pixel,p(x,y)when an error occurs. horizontal estimate would have been correctly chosen. Thus, the As in the case of the linear estimator, a similar system can be minimum -difference technique has an important advantage over implemented for the chrominance signals by time -multiplexing linear estimators in that it has perfect response to horizontal or them and modifying the delay -line structure. However, a signifi- vertical edges. In addition, the increase in hardware complexity cant simplifcation can be achieved by obtaining the minimum - over linear estimators is really quite small. difference information from the luminance error -concealment The minimum -difference algorithm is not without its own channel, thus avoiding the replication of the minimum -difference problems, however, since it can sometimes be "fooled" into decision -making circuitry in the chrominance channel. This sim- estimating in the wrong direction by very -high -frequency picture

Reitmeier Digital videotape recorders: Tape format and error -concealment considerations 41 Fig.7. The results of error concealment by a more sophisticated adaptive estimator. Note the improvement over linear Glenn Reitmeier obtained his B.E.E. degree summa cum laude estimation. The remaining artifacts occur only in areas of from Villanova University in 1977, and received the Dean's Award high diagonal resolution. for Academic Excellence. He joined RCA Laboratories in 1977, and received his M.S.E. in Systems Engineering from the Univer- content or by diagonal edges. Slightly more sophisticated control sity of Pennsylvania in 1979. Since joining the Laboratories, Mr. Reitmeier has been performing research in the field of digital tele- over the selection of horizontal or vertical estimates can be vision, particularly in the areas of multidimensional signal pro- achieved by examining more of the spatially adjacent pixels, and cessing and the development of system concepts for digital video these techniques provide great improvements in the concealment tape recording and for digital television studios. He received two performance with only a minor increase in hardware complex- RCA Laboratories Outstanding Achievement Awards, one in ity. The results from the use of such an adaptive concealer are 1979, for the application of digital image processing techniques to broadcast television, and a second one in 1981, for contribu- shown in Fig. 7, and this level of high performance and reason- tions leading to the establishment of a worldwide sampling able complexity is very well suited to a practical DVTR. standard for digital television. Mr. Reitmeier served as the Secre- tary of the Working Group on Digital Video Standards in the Society of Motion Picture and Television Engineers during 1980 Conclusions and 1981, and is a member of Sigma Xi, Tau Beta Pi, Eta Kappa Nu, and Phi Kappa Phi. Many technical obstacles must be overcome before the DVTR Contact him at can become a commercial reality. For example, the conflicting RCA Laboratories design requirements for extremely high bit -packing density (need- Princeton, N.J. ed to provide reasonable tape consumption) and for tight mechan- TACNET: 226-2523 ical tolerances (required for tape interchangeability) must be resolved. This is only one of the many difficult questions that must be solved and agreed upon by standardization committees, such as those in the Society of Motion Picture and Television Engineers (SMPTE) and the European Broadcasting Union (EBU). However, the problem of managing errors must inevi- References tably be addressed in any digital recording or transmission sys- I.J.L.E. Baldwin, "Digital Component Equipment in an Analog Environment- tem, and the combination of simple error -detecting -and -correct- Will It Work?" Proceedings of the 13th International Television Symposium, ing codes with sophisticated error -concealment techniques is a Montreux, Switzerland (June 1983). very powerful approach. The appropriate use of tape format to 2. H. Schachlbauer, "Analogue Components-A Useful Complement for the Digital Studies Standard," Proceedings of the 13th International Television Symposium, distribute dropout errors in the television raster allows the use of Montreux, Switzerland (June 1983). two-dimensional signal processing to conceal errors. 3. R.N. Hurst and K.H. Powers, "The Development of International Television Linear estimators suffer from their poor response on edges Standards," RCA Engineer, Vol. 28, No. 5 (September/October 1983). and from high frequency patterns, which result in objectionable 4. F. Davidoff, "Digital Television Coding Standards," IEE Proceedings, Vol. 129, artifacts. Adaptive estimators can be designed to achieve excel- No. 7, pp. 403-12 (September 1982). lent performance without requiring excessive hardware complex- 5. H. Yoshida and T. Eguchi, "Considerations in the Choice of a Digital VTR For- mat," SMPTE JournaL Vol.91, No. 7, pp.622-6 (July 1982). ity, and can indeed provide broadcast -quality error concealment 6. J.L. Koslov and C.R. Thompson, "Channel Coding Strategies for Digital Televi- for digital videotape recorders and digital video transmission sys- sion Tape Recording Equipment," Proceedings of the 12th International Television tems, offering high quality at a low cost. Symposium, Montreux, Switzerland (June 1981).

42 RCA Engineer 28-5 Sept./Oct 1983 Somewhere in the world another engineer has done something

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RCA Engineer 28-5 Sept./Oct. 1983 43 A. Acampora

Wideband picture detail restoration in a digital NTSC comb -filter system

Digital filters used with the digital comb -filter provide chrominance-detail separation with wider bandwidth vertical detail placement.

The separation of NTSC video signals Spectrally, the comb filter actually con- to extract this luminance detail from the into their component parts, luminance (L) sists of two complementary sinusoidal fil- chrominance signal for reinsertion into the and chrominance (C), is an important step ters, one to pass only luminance spectral luminance channel. Conversely, a bandpass in the implementation of many video -pro- pickets and another to pass only chromi- filter can extract the chrominance informa- cessing systems. A comb filter, usually the nance spectral pickets and their respective tion from the combined chrominance-plus- first unit in a separation system, takes advan- sidebands. In a signal without sharp verti- luminance-detail signal. Note that some tage of the line -to -line correlation of lumi- cal transitions, the sidebands do not extend high -frequency vertical detail information nance and line -to -line phase reversal of far from the corresponding pickets and the might not be recovered, because itfalls chrominance to achieve separation.' In the comb filter adequately separates L and C. into the chrominance frequency range. How- case where each line is the same as the However, a vertical transition results in a ever, this high -frequency vertical detail is previous one, such as a vertical color bar widening of the sideband structure, caus- not generally observable and its loss does test signal, the comb filter provides excel- ing some luminance information to fall not significantly reduce picture quality. lent separation of L and C. However, if into the stopband of the L comb filter and, Figure 1is the block diagram of a sys- the signal contains dissimilarities from one consequently, into the passband of the C tem to separate luminance (L) and chro- line to the next, then these vertical transi- comb filter. Similarly, chrominance infor- minance (C) and also to restore the verti- tions become "smoothed" in the L and C mation appears at the output of the L cal detail. A one -line (1H) delay and two outputs. For example, a sharp black -to - comb filter during vertical transitions. The full adders comprise a comb filter, produc- white luminance transition results in a black - smoothing of luminance vertical edges is ing luminance minus vertical detail (L- to -gray -to -white transition in the L signal- called a loss of vertical detail. VD) and chrominance plus luminance ver- a loss of vertical definition. The chrominance signal has a much tical detail (C+VD). A bandpass filter ex- narrower bandwidth than the luminance tracts chrominance from the C+VD signal signal and, consequently, does not supply while a lowpass filter extracts vertical detail Abstract:There are many video signal much detail to the picture. Because of this from the same signal. The L-VD signal is processes where NTSC composite signals quality, the vertical smoothing effect of the delayed by an amount equaling the low- are separted into the luminance and comb filter on chrominance is not a great pass filter delay, and is summed with the chrominance components. The common concern. However, it is vital that separated vertical detail to produce restored lumi- method of accomplishing this is line comb- luminance have good vertical and horizon- nance. ing. In such cases, the separated signals tal resolution such that the smoothing of suffer noticeable loss of vertical resolution. luminance vertical edges is quite apparent. This image detail can be recovered using The signals necessary to restore the lumi- Filter specifications appropriate filters and re-insertion hard- nance vertical resolution exist along with It is difficult to define suitable bandwidths ware. This paper describes the mechanism the chrominance signal at the chrominance and cutoff frequencies for the filters men- for restoring vertical detail, over as wide a comb -filter output. Fortunately, chromi- tioned above. Although itis desirable to bandwidth as practical, by using digital fil- nance energy is centered at the 3.58 -MHz retrieve as much vertical detail as possible, ters to recover the missing picture detail. color subcarrier, extending at most 1.5 MHz chrominance bandwidth must not be severe- down from this point, while the misplaced ly compromised. Regardless of their cutoff C)1983 RCA Corporation Final manuscript received June 21. 1983. vertical detail is concentrated in the 0- to frequencies, the lowpass and bandpass fil- Reprint RE -28-5-7 2 -MHz range. This allows a lowpass filter ters of Fig. 1 must not introduce signifi-

44 RCA Engineer 28-5 Sept./Oct. 1983 Why wider bandwidth detail restoration? The digital filters presented in this article have wider bandwidths than the analog filters currently used to extract vertical detail in pictures. This wider response (by nearly a factor of two) improves the spatial frequency response over a larger range of spatial angles, especially those angles along the diagonals. As discussed in the article, CHROM IN ANCE - LUMINANCE widening the passband response SEPARATION requires sharper skirt selectivity to avoid inserting chrominance Fig. 1. By adding and subtracting a composite video signal from the same signal dots, along with the desired pic- delayed by one horizontal line (1H), luminance and chrominance can be separated. ture detail, into the luminance. However, vertical detail must be recovered by lowpass filtering the chrominance, This higher selectivity creates the and inserting those low frequency signals back into luminance. problems of delay equalization near the passband edges, and the threat that the filter step response will cause "ringing." T3 Both of these occurrences create SHIFT T2-0-1 noticeable artifacts in the picture. REGISTER The digital approach described overcomes both these design problems. First, a symmetrical digital filter design has linear C C1 co c, C2 C3 phase (and therefore no delay distortion) everywhere in its 12I 1 1 ACCUMUL ATOR OUTPUT response. Second, the choice of tap spacing and coefficients controls both the frequency and step Fig. 2. In the digital filter implementation, the data is clocked through shift register response so that a suitable com- stages. Selected register outputs are weighted and accumulated with other weight- promise can be made with regard ed taps to form the desired frequency response. to filter rejection, and "ringing" artifacts. cant phase distortion. This means the fil- General filter configuration ters must be of a linear phase type or have The form for the digital filter just described suitable phase compensation. is shown in Fig. 2. Here, the signal at the A filter with zero gain at 3.58 MHz and Linear -phase -response filters can be real- center of the filter is weighted byCOand unit gain at dc for the lowpass filter, and ized using a tapped -delay line. In a tapped - accumulated with other symmetrically - vice -versa for the bandpass filter. delay -line filter, a number of delay incre- placed pairs of taps-each respectively mul- A filter using binary coefficients, that is, ments are placed in series, and signal is tiplied by weighting factors by C1,C2, coefficients that are a power of 2 or a tapped off after each delay. Each of these C3, and so on. These taps are each dis- sum of powers of 2. signals is multipled by a weighting factor placed by delay increments T1, T2, T3, and, finally, all are summed together to The first criterion suggests that a maxi- and so on. The variables to be selected mum of four taps be used. The second produce the output. To obtain linear phase, include the tap weights, the tap spacings, and third criteria determine the tap spac- the weighting factors and delay increments and the total number of taps. ing and weights. In a digital implementa- must be symmetrical about the center point These variables go hand -in -hand with tion, the delay increments T, , T2, ... must of the delay line. This type of filter can be the characteristics of the filter to be de- readily implemented in a digital system, be integral multiples of the clock frequency. signed.In the case of vertical detail/ Further, the popular clock frequency for where exact delay increments (that is, the chrominance separation, some important digitizing an NTSC video signalis four duration of the clock period) are available properties are: through the use of shift registers. Because times that of the color carriers, or approx- of this, the remainder of this paper will A filter that is simply implemented. imately 14.32 MHz. Therefore, the small- focus on the development of digital filters A filter that preserves as much vertical est delay increment is about 70 ns.In used with a digital comb filter to provide detail without compromising the chro- addition, since the clock rate is related to chrominance-luminance separation with minance signal, that is, has a good shape color subcarrier,itis convenient to also wideband vertical detail placement. factor. relate the filter cut-off frequency to this

Acampora: Wideband picture detail restoration in a digital NTSC comb -filter system 45 subcarrier. Within the constraints of pass- any integer, is merely a bit shift ofnplac- highly desirable to choose coefficients that ing as much detail signal as possible up to es. Consequently, in a parallel -wired dig- can be expressed in this way. However, 2 MHz, a natural 6 dB cut-off of one-half ital system, multiplication by powers of 2 choosing coefficients in this manner may subcarrier (approximately 1.8 MHz) seems can be wired -in and, therefore, require no not always be consistent with the previous adequate. This, coupled with the second multipliers. Also, multiplication by a fac- considerations of filter shape. But, starting from and third criteria, yields tap spacings of Ti tor that is a sum of any number of these an initial choice of Fourier series coeffi- = 2 docks,T2 =6 docks, andT3 =10 docks. powers of 2 reduces to an addition pro- cients for Co, C1, C2, andC3,and massag- The final criterion is important from a cess. For instance, the factor 3/4 equals ing these coefficients towards the binary digital -implementation viewpoint because 1/2 plus 1/4 so multiplication by 3/4 can constraint seems practical. Some practical it eliminates the need for multipliers. Mul- be accomplished by adding 1/2 of the sig- considerations that also enter into the tiplication by a factor of r, where n is nal to 1/4 of the signal. As a result, it is choice of coefficients are: 1. To achieve unit gain in the passbands- Co + 2(C1 + C2 = C3) = 1; VIDEO IN 2. To provide about 5% of pre- and post - D D D D D D0 DD DDD shoot (prior to any nonlinear processing) on the vertical detail-I C2 + C3 I OUT -2 = 0.05; and 3. To avoid excessive ringing on these

+ =LPF edges, IC3 I 5_ 0.02. These constraints -=BPF lead to coefficients of Co =1/2,C1 = -16 5/16, C2 =-5/64, C3 =1 /64 .

The actual filter The final form of the filter is shown in Fig. 3. The tap spacings are set as de- +64 scribed earlier. Each delay block"D"corresponds to one stage of a shift register clocked at four times the color carrier. +16 Notice that the coefficients are derived by successive addition of fractional powers of LPF / HPF two. Also, since digital full adders are two - BLOCK DIAGRAM port devices, the actual accumulation is accomplished through a series of additions. Fig.3. In the final form of the filter, each delay block D corresponds to one stage An intrinsic property of the filter is that of a shift register clocked at 4 times the color subcarrier. The coefficients are both lowpass and bandpass versions are derived by successive additions of fractional powers of two, thereby avoiding costly obtained from the same hardware configu- multipliers. ration by either adding the accumulated

25 ES

O 0

.0-25 - 0

-I -i 50

75 LOWPASSRESPONSE - -75 - BANDPASS RESPONSE

100 -100 I I a 4 6 8 0 6 (a) (b) FREQUENCY MHz FREQUENCY MHz Fig.4. Theoretical lowpass and bandpass responses. (a) The lowpass response shows excellent passband flatness and selectivity for filtering the vertical detail. (b) The bandpass response is centered at 3.58 MHz, and filters the chrominance information.

46 RCA Engineer 28-5 Sept./Oct. 1983 Fig. 5.The measured responses closely match the theoretical ones given in Fig. 4. The scale in the photographs is 10 dB/division vertically, and0.5MHz/division horizontally. tap pairs to the center -tap (LPF) or sub- Acknowledgment Reference tracting them from the center -tap (BPF). Many thanks to Gary Saulnier, now at 1. D.H. Pritchard, "A CCD Comb Filter for Color TV MIT, who, as a summer student in the Receiver Picture Enhancement,"RCA Review,Vol. Rensselaer Polytechnic Institute co-op pro- 41, No. I, pp. 3-28 (March 1980). Results gram, provided invaluable help in the filter The analytical results of this filter are shown design and implementation. in Figs. 4a and 4b for the lowpass and bandpass cases, respectively. The measured Al Acampora joined RCA in 1959, at the responses of these filters are also shown in Advanced Communications Laboratories Fig. 5. These measurements, taken with a in New York. His work involved all phases spectrum analyzer, show the digital circuit of military and commercial communica- does indeed approximate the theoretical tions. In 1970, he joined RCA Global Com- munications, as Staff Engineer and, in case. 1973, he was awarded the David Sarnoff The response is down 6 dB at 1.8 MHz Outstanding Achievement Award for his and remains no less than 30 dB down work in narrowband video transmission. over the range of the color sidebands. No- Since joining RCA Laboratories, Princeton, tice that there is extremely high rejection New Jersey, as a Member of the Technical Staff in 1978, Al has continued his work in in the high -color -energy region around 3.58 communications systems. His initial pro- MHz. The response to a vertical step with grams involved video processing for tele- the chosen coefficients has a "ringing" term conferencing applications. He has been of about 1.5% and pre- and post -overshoots involved in digital implementation of video - of 6.25%. processing systems, especially for existing and next -generation satellite transmission, For an 8 -bit parallel input, satisfactory and he has contributed to the development operation was found by using 12 -bit accu- of digital television receivers. In 1982, he mulators within the internal summations was promoted to Senior Member of the of the filter. The final result was truncated Technical Staff. Contact him at to 10 bits. Additionally, care was taken to RCA Laboratories properly pipeline the digital filter to account Princeton, N.J. for internal path delays. TACNET: 226-2773

Acampora: Wideband picture detail restoration in a digital NTSC comb -filter system 47 W.E. BabcockW.E. RoddaW.F. Wedam

Some power considerations for consumer -typehigh -definition -television displays

Power dissipation in the display -related circuitry and components will have a decisive influence on television receiver design, as new technology and digital processing techniques lead the way to the high-performance television systems of the future.

Further improvement in the quality of ment in observed picture quality through kHz may be considered for some Euro- the picture displayed by commercial tele- the elimination of certain artifacts in the pean systems), but would not require any vision receivers is difficult to achieve within picture. change in the transmitted signal. There- the framework of existing display tech- Almost all techniques under evaluation fore, there would be no effect on repro- niques. Additional improvement could be for improvement of observed picture qual- duction of pictures by receivers already in obtained through improvements in color ity require a change in the horizontal scan- the field.Benefits of the non -interlaced picture tubes, better signal processing, and/ ning system from the current 525 -line inter- scanning system would be the almost com- or through modification of current NTSC laced system to a 525 -line non -interlaced plete elimination of such artifacts in the standards. Approaches are being explored (progressive -scan) system. This would in- picture as large -area flicker, interline flicker, that do not require a change in transmis- volve an increase in the horizontal scan- line breakup, and line crawl. sion standards, but provide an improve- ning rate from 15.75 kHz to 31.5 kHz (48 If standard deflection techniques are used and the ratio of trace time to retrace time is kept constant, operation of the horizon- Abstract:One technique under evalua- scanning switch. It also results in an tal scanning system at double the normal tion for improvement of observed picture increase in the high -frequency losses in the scan rate presents major problems due to quality is a change in the horizontal scan- deflection yoke. When the scan rate is stresses imposed on the horizontal output ning system in the receiver from the cur- doubled the bandwidth of kinescope driv- transistor and damper. It also results in rent 525 -line interlaced system to a 525 - ers also must be doubled to maintain reso- increased high -frequency losses in the deflec- line non -interlaced (progressive) system. lution, and in turn, this can affect power tion yoke. The bandwidth required for This would involve an increase in the dissipation. kine-drive circuitry is doubled for the same horizontal scanning rate from 15.75 kHz This paper was presented to the horizontal resolution in the picture. This to 31.5 kHz (48 kHz may be considered SMPTE Study Group for HDTV and is paper presents the results of an investiga- for some European systems), but would intended to familiarize engineers who are tion of switching device and deflection not require any changes in the transmitted not commonly involved in the design of yoke losses for horizontal scanning rates signal. Benefits of the non -interlaced scan- display systems with the issues of high - from 15.75 kHz through 63 kHz, covering ning system would be the almost complete definition displays for consumer products. the complete range under consideration elimination of such artifacts in the picture Some parts of this paper were rewritten for U.S. and European consumer televi- as large area flicker, interline flicker, line and new parts have been added Conven- sion as well as for high -resolution compu- breakup and line crawl tional power, deflection and kinescope ter displays. Kine driver design and dissi- Operation of the horizontal scanning drive circuitry and its limitations will be pation is discussed for bandwidth to 32 system at double the normal scan rate examined and some difficulties of apply- MHz. presents major problems in the stresses ing it to high -definition television will be shown. imposed on the active devices used in the Basic horizontal deflection circuit ©1983 RCA Corporation In its simplest embodiment, the horizontal Final manuscript received August 25. 1983. Reprint RE -28-5-8 deflection system of a conventional televi-

48 RCA Engineer 28-5 Sept/Oct. 1983 until the end of trace. Storage times of typical devices vary from 4µs to 10 As. The EDC transistor base drive must be off or re-

11 versed at a time that is 4 to 10 As before II ISOLATION L II(FLYBACK) the transistor turns off. 11 The turnoff time of the horizontal output transistor will increase slightly with higher collector currents and proper base drive will be difficult if storage times are high and on -times are reduced. Turnoff waveforms are dependent on the base drive HOR. YOKE as well as on the characteristics of the transistor, so the rms value of the transis- HOR. tor current during turnoff isdifficult to OUTPUT predict. For the calculations in this paper, the turnoff current of the transistor was assumed to follow a ramp.* Fall time, as Fig.1. Basic horizontal deflection circuit.The horizontal deflection system of a published by the transistor manufacturer, conventional television receiver consistsof a magnetic deflection coil, a power is measured between the 90 percent and source and one or more switches. 10 percent points on the curve and may vary from 0.4 µs to 1µs, depending on sion receiver consists of a magnetic deflec- yoke would be the same, regardless of the the manufacturer. Since the rate of change tion coil, a power source and one or more scanning rate. of current before the 10 percent point and switches. Figure 1 shows such a deflection The yoke current is not normally an after the 90 percent point is less than it is system while Fig. 2 shows its associated ideal sawtooth waveform. The S -shaping between these two points, the turnoff time current and voltage waveforms. capacitor in series with the yoke produces has been assumed to be approximately 1.3 The switch in this case is a combination a slight "flattening" of the waveform near times the fall time. Under improper drive of a transistor and a diode (damper). The the beginning and end of trace time, while conditions, a turnoff current may have a circuit includes a retrace capacitor CR that, the retrace capacitor in shunt with the long "tail" extending well into retrace time. together with the deflection coil L, and yoke produces a sinusoidal current wave- Although the magnitude of this tail may the flyback coil, determines the length of form during retrace. Measured be quite low and the dissipation associated the retrace interval. It also includes capaci- yoke current indicate that the actual rms with it quite low, it can be very destruc- tor C, which provides the dual function yoke current is tive, because the current during this inter- of dc -blocking and S -shaping. An actual val is carried by a tiny fraction of the tran- Irms = (2/3) /,,A,, peak deflection circuit used in a receiver would (I) sistor chip area. normally also include pincushion- and lin- This value is used for the calculations in For state-of-the-art horizontal output de- earity -correction circuitry plus a winding this paper. vices, the current gain may be 3 or less. on the flyback coil to provide a source of The peak voltage on the yoke and on Since it is imperative that the device remain high voltage for the picture tube. The cor- the deflection switch is inversely propor- saturated during trace time, a base drive of rection circuitry and the high -voltage gener- tional to retrace time. Therefore, for a 0.4 times the collector current is not out of ation can cause the delivery, by the deflec- given deflection yoke, if the scanning rate the question, and this value is used for the tion system, of 50 extra watts of power, is doubled and the retrace time is cut in calculations of dissipation resulting from and consequently can increase the current half, then the peak yoke voltage will dou- base drive. flowing in the switch devices. The effects ble and the peak switch voltage will nearly Tuning effects from the high -voltage fly- of this additional power on dissipation in double. If these components will not with- back transformer can also influence power the switching devices has been ignored in stand this high voltage or will not have an dissipation, especially during retrace. The this paper, but the probability of this added adequate safety factor, then yoke induc- analysis, on which this paper is based, dissipation should be kept in mind by the tance must be decreased and peak current does not include variations due to tuning circuit designer. must be increased to keep the peak vol- effects, but such effects can influence the tage within the desired limit and still have dissipations in the circuit, in some cases, sufficient scan. substantially. Factors affecting deflection A voltage of about 1000 volts is consid- Power dissipation as a result of leakage switch and yoke dissipations ered to be a safe design voltage for con- currents during retrace has been ignored For purposes of this investigation, it was ventional deflection yokes and switching because such effects are usually very low assumed that deflection -yoke materials and devices. Therefore, for the calculations and in silicon devices. The effects of the satura- geometries now being used in television measurements described in this paper, yoke tion voltage of the horizontal output tran- receivers would continue to be used at the inductance and peak currents were adjusted sistor during storage time depend on the higher scanning rates and that the ratio of to keep the peak switch voltage below trace time to retrace time would be a con- 1000 volts. * This assumption yields a dissipation thatisslightly higher than the actual value at 16 kHz. An assumption stant for all scanning rates. Therefore, for a The storage time of the horizontal out- of a parabolic waveform (see Reference I) yields a given deflection angle and high voltage, put transistor increases with peak collector dissipation value somewhat lower than the actual value, the peak stored energy in the deflection current if saturation is to be maintained although the calculations are rigorously correct.

Babcock/Rodda/Wedam: Some power considerations for consumer -type high -definition -television displays 49 output transistor should be operated at a junction temperature below 115°C in order RETRACE to avoid any lengthening of fall time that TD Trrs- rip- DIODE could lead to a thermal runaway condi- I CONDUCTION I tion. In the example just given, if the fall

I TIME ly time were to increase from 0.4 ps to 1µs, the transistor dissipation would increase by a factor of almost three to about 4.3 watts. TRANSISTOR The power dissipated by the damper is CONDUCTION TIME a function of the rms damper current and Tt I Wr the conducting voltage drop across the damper. If the damper is used with the vy horizontal output transistor in the previous example, the power dissipated by the damp- 0 er is 0.4 watts. It is assumed that there is no direct fre- EDC quency -related dissipation in the damper IC diode. Horizontal output transistor and damper dissipation at other scanning rates may be calculated in the same manner as for the example just given. Although transistor stor-

0 age time and turnoff time will increase slightly at higher scan rates, it is assumed ID that, with careful adjustment of the base drive and with a specially selected hori- DRIVE zontal output transistor, the previously -used ON DRIVE OFF turnoff values can be used. The results of these calculations are listedin Table I. B Other assumptions made are

0 1. Direct -current supply voltage is the same for all scan rates 2. Peak stored energy in the yoke is constant for all scan rates. j L....._STORAGE TIME 3. Ratio of trace time to retrace time is constant for all scan rates. 4. Transistor fall times liein the range lc from 0.4 to 1µs. 5. Peak retrace voltage is the same (990 volts) at all scan rates. 6. The waveform of the retrace voltage across the trace switch is a half sine wave. Fig. 2. The waveforms in a basic horizontal deflection system. Shown from top to 7. Dissipation due to leakage currents in bottom: yoke current, yoke voltage, transistor current, damper diode current, tran- the horizontal output transistor and damp- sistor base current, retrace capacitor (CR) current. er during retrace is negligibly small. design of the base -drive circuitry and on base drive, and the dissipation during re- Measurement of yoke dissipation the characteristics of the transistor. trace. The power during retrace represents the Calculation of dissipation in the deflection scan -frequency -dependent portion of the yoke is very difficult, so these losses were Trace switch power dissipation transistor dissipation. The total power dis- determined by actual measurement. Tests The power in the horizontal output switch sipation in a fast horizontal output transis- were run using approximately 4.7 mJ of stored can be separated into two parts: the power tor, at 16 kHz, was calculated to be 1.47 energy in the yoke. This approximates the dissipated in the transistor and the power watts (see Table I). This appears to be a stored energy required for horizontal deflec- dissipated in the damper diode. The power low dissipation for a device in a TO -3 tion using a 110° picture tube operating at dissipated in the transistor is the sum of package. However, since fall time of the a high voltage of 30 kV. The circuitry the power dissipation due to collector cur- collector current is temperature -dependent used for the dissipation measurements is rent during trace, the dissipation due to as well as drive -dependent, the horizontal shown in Fig. 3.

50 RCA Engineer 28-5 Sept./Oct. 1983 Table I. Horizontal output transistor and damper dissipation at different scan rates. Transistor dissipation rises almost exponentially while damper dissipation rises lin- early with scan rate. Scanning rate Retrace time Peak retrace DC supply Peak switch Peak base Transistor dissi- Damper dissi- (kHz) (Tr)in /,ts volts (Vs) volts (Eoc) current (A) current (A) pation* (W) pation (W) 15.75 12 990 128 3 1.2 1.4 to 4.3 0.4

31.5 6 990 128 6 2.4 7.6 to 28.7 0.83 48 3.94 990 128 9 3.6 19 to 84 1.3

63 3 990 128 12 4.8 35 to 165 1.8

* Lower value is for fall time of 0.4 1.1s. Higher value is for fall time of 1

The base -drive circuit shown in Fig. 3 was not intended to be an optimum drive 0 - 30V POS. DC SUPPLY DC SUPPLY circuit for a specific frequency. However, it provided a convenient method of sup- 0.33 plying adequate drive with good turnoff capability at all desired scanning rates with- 5000 µF (]- out the problem associated with optimiz- II 18 mH ing a base -drive transformer for each scan- II II FLYBACK COIL ning rate. The positive supply to the drive II (ISOLATION INDUCTOR) transistors was adjusted to provide the re- 2N6473 quired forward base drive, while the negative supply was adjusted to provide ample RETRACE turnoff drive with minimum turnoff "tail" 2N6754 !CAPACITOR 1.2 µF. DAMPER of the horizontal output transistor collector 0.0151 HOR. YOKE current. Since the power input at the higher 2N6109 COILS scanning rates was considerable, the horizontal output stage was cooled by direct- 0.43 ing a fan at the heat sink being used. 680 i.LF The diode unit of an ITR (selected to withstand 1000 volts) was used as a damper I and it was bolted directly to the heat sink in order to keep its temperature to a safe value. Although a conventional damper diode would have been satisfactory at the 15.75 -kHz scanning rate, its slow turn -on 0 - 30V characteristic made itunsatisfactory for NEG. DC SUPPLY either 31.5 -kHz or 63 -kHz operation. In Fig. 3. Test circuit for measuring yoke losses. This is similar to the basic deflection addition, the dissipation resulting from the circuit in Fig. 1. The push-pull drive circuit can be optimized for the different scan high forward current mandated a damper frequencies. The current and temperature of the horizontal yoke coils is monitored diode that, could be mounted with good during the test. thermal contact to the heat sink for adequate cooling. millihenries (mH) at 15.75 kHz to 65 AH power -dissipation curve is shown in Fig. A conventional horizontal output tran- at 63 kHz. Tests were run on a yoke using 4. This curve was used to convert core sistor has such slow turnoff that it invari- RCA 804 ferrite and on yokes using cores temperature rise, during the test, into yoke ably fails within a few seconds operation made by two other ferrite suppliers. Except dissipation. at 63 kHz. However, it was found that a for differences in the core material,all The vertical yoke winding did not carry device originally designed for high -fre- three yokes were identical in construction. any vertical deflection current during the quency inverter operation, turned off in tests. However, the vertical windings are about 200 ns, and performed quite well at A thermocouple was cemented to the normally shorted at the horizontal fre- 63 kHz (RCA 2N6754). Therefore, this core of each yoke in order to measure quency by the vertical circuit, so the verti- device was used as the horizontal output core temperature. The entire yoke was cal coils were shorted during the test by a transistor in all the tests. placed inside an insulated container and a large capacitor (0.33 µF). Deflection yokes used for the yoke dis- second thermocouple was suspended inside Power dissipation in the deflection yoke sipation measurements were made with the container approximately two inches results from three factors multiple horizontal windings. All the wind- above the yoke to measure ambient temper- 1. 12Rlosses in the windings. ings were used in each test, but they were ature. A curve showing core -temperature connected in the appropriate series, paral- rise above ambient versus total power dis- 2. Eddy current losses in the windings. lel, or series/parallel combination to pro- sipation was obtained for each yoke by 3. Hysteresis and eddy current losses in vide inductance values ranging from 1.04 applying dc power to the yoke. A typical the ferrite yoke core.

Babcock/Rodda/Wedam: Some power considerations for consumer -type high -definition -television displays 51 hours of operation, the inductance of the 100 winding dropped drastically and peak yoke current increased significantly. Attempts to run this yoke at 63 kHz were abandoned. Horizontal deflection yoke loss for the MMENEMINMIBEHM.M1Mff.= three yoke core materials tested at 15.75, r...... 50 MMIN 31.5, and 63 kHz are plotted as a function r- of frequency in Fig. 5. Although the yoke

...... using ferrite "A" core material could not

...... be tested at 63 kHz, an extrapolation of ...... the curve out to 63 kHz is shown dotted to provide an indication of the losses that might occur if some way (such as fan 20 cooling) could be found to keep the core temperature below the Curie point. The curves in Fig. 5 show that, at the 15.75 kHz scanning rate, the combined hysteresis and eddy current losses are about equal to the 12R losses in the windings. As the scanning rate is increased, and the retrace 4 time is shortened, core losses and eddy current losses in the copper become a large portion of the total loss. 5 One interesting observation, upon examining the curves of Figs. 5a and 5c, is the difference in core loss between RCA 804 material and ferrite "B" material. At 111 the 15.75 -kHz scanning rate, the two materials have essentially the same loss. At 31.5 kHz, the core loss for RCA 804 material is about 30 percent less than for ferrite "B" material. However, at 63 kHz, ferrite "B" material has a total loss about 20 percent less than RCA 804 material. This probably is due to the relative effects 2 5 10 20 50 100 of hysteresis and eddy currents on the total Temperature Rise Above Ambient - Degrees C core loss. At 15.75 kHz, the total loss is primarily Fig. 4. Calibration curve for yoke dissipation. A curve like this, showing core - due to hysteresis and at that scan rate, the temperature above ambient versus total power dissipation, was obtained for each two materials have similar losses. At 31.5 yoke by applying dc power to the yoke windings. kHz, hysteresis is still the dominant factor, but the 804 material shows lower hystere- /'R losses in the deflection coil are not At the higher scanning rates there will sis loss. However, at 63 kHz, eddy cur- a function of frequency. However, since be some increase in core loss and copper rents become a significant factor and, since the coil is heated by the ferrite core, which eddy current loss during trace time, but ferrite "B" material has much higher resis- does increase in temperature as frequency most of these losses will still occur during tivity than 804 material, it has lower eddy increases, the copper resistance will increase the retrace interval. An approximate value current loss. with frequency. for the loss occurring during the 6.1 -As Figure 6 shows a typical curve of yoke 12R losses in the windings can be cal- retrace interval at 31.5 kHz can be obtained dissipation as a function of retrace time. culated quite easily when the rms yoke by increasing the retrace capacitor to obtain At the very short retrace times used for current and winding resistance are mea- a retrace time of 12.3 As and noting the the higher scanning rates, the losses increase sured at the operating temperature. How- decrease in dc power to the deflection sys- rapidly. For example, if the retrace time at ever, there is no practical way to separate tem. Similarly, the decrease in dc power a scanning rate of 31.5 kHz is increased eddy current losses in the winding from to the deflection system at the 63 -kHz from 5µs to 7 As, the yoke losses are hysteresis and eddy current losses in the scanning rate when retrace time is increased reduced by about 1.8 watts, or about 12 ferrite. When the 121? losses at the 15.75 - from 3.1 to 6.1 µs can be used to obtain percent. This suggests that,if the yoke kHz scanning rate with a retrace time of an approximate value for the losses occur- temperature is close to the 105°C maxi- 12.3 As are subtracted from the yoke losses, ing during retrace at 63 kHz. mum rating or slightly above, it might be the sum of eddy current losses in the yoke One of the core materials tested (ferrite reduced and kept within the desired temper- windings and the losses in the ferriteis "A"), apparently had a rather low Curie ature rating by a slight increase in the about 3.6 watts. Practically all of this loss temperature and it was not possible to retrace time. If a large decrease in yoke occurs during the retrace interval. operate it at 63 kHz. Within less than two temperature is required, it may be neces-

52 RCA Engineer 28-5 Sept./Oct. 1983 100 too: 100 Scan Rate Retrace TYoke L Scan Rate Retrace TYoke L 7 Scan Rate Retrace TYoke L 15.75 kHz 12.2ps 1068 pH 15.75 kHz 12.3µs 1040pH=-- 15.75 kHz 12.2ps 1085 pH 31.5 kHz 6.05 ps 265 pH 31.5 kHz 6. ps 260pH-- -..= 31.5 kHz 6.08 ps 260 pH 63 kHz 3.03 ps 67.7 pH 63 kHz 3. ps 65pH - -- 63 kHz 3 ps 67.5 pH. 50 50 - 50 3E9 rasVrA ====MIA619EMEryj l. --...... ====M.aE.E.If.' 30 30 ======7Z',.,...... ,...... 13.1" 30 /-i .....e.mamassame=="'",:n ammo==.1. F.:17 , 20 20 20 ,-,--4- 4, r 0 .0,4';.:.f?,5!r .:: .. AN - - i.... MM. .0 , 3 111111111111M111 IOC sk MN RE Illiii PII W WINN io g 10 _____411111111/ Mme' H 10 =raw, imino ;ft _----_-i=-_-_-=-4 0 WAWA y Immo 3,--_-= F EM -0-== EMMEN 20 O IMMUNE O ==5.1 -TEE 0 -.....=-----7=7:2 _Atom a 3 5 1111111110.1 ...... '="===W...... 5 5 sseS C°99e( a. 7-,- oOPPe- I 7: - 4 4 t--- 8; Pper 4 mie 12R Lossesin r,...... 2ik EM = ...... 3 3 3 ------"=.w.EtEEMEI gylLI Mii:Coliiiiig 2 2 2 WriEepos ri inagen=MOINIsi NM= - MManH,I. , 1 , UJ-' 110 15 30 50 100 10 15 30 50 100 50 10 15 30 100 Scanning Rate - kHz Scanning Rate - kHz Scanning Rate - kHz

Fig. 5.Deflection yoke losses as a function of horizontal scanning rate and different ferrite materials. Material "A" is lowest in loss at 16 kHz, butcould not be operated above 32 kHz because of low Curie temperature. Dissipation ofall materials is excessive at 64 kHz. sary to use a lower -loss core material, to to 31.5 kHz can halve the active scan time a Vcc supply of typically +200 volts with use litz wire for the windings, or change and necessitate a video circuit bandwidth substantial current source capability. Typi- the flyback tuning to reduce the harmonic of approximately 8.4 MHz for equivalent cally, the V88 is +11 volts at low current content of the retrace pulse. horizontal resolution of the NTSC signal. requirements, and V EE is +3.4 volts with Successful implementation of higher scan- With regard to video -circuit power dis- substantial current sink capability. The ratio ning rate systems in television receivers sipation, greatest demands are imposed by of R L to R E typically ranges from 40 to will probably include new circuit ap- the output driver stages that must provide 80. The capacitance CL includes Q2's col- proaches as well as improvements in de- at least 100 volts peak -to -peak video atlector -base capacitance, stray wiring and vices and in deflection yokes. the picture -tube cathodes. Increased driver - picture tube socket capacitance in addition circuit bandwidth, to accommodate a high - to the picture tube electrode capacitance. definition system, generally entails increased Typically, CL z 12 pF. A peaking coilL Video circuits power dissipation and higher -performance is usually included in Q2's collector circuit National Television System Committee output transistors. An analysis has beento extend the circuit bandwidth by a fac- (NTSC) standards provide a maximum made of the power required by output - tor of approximately 1.7. video signal bandwidth of approximately driver circuits of the type used in conven- If the gain -bandwidth products of Q1 4.2 MHz with a 15.7 -kHz horizontal line tional receivers when redesigned to meetand Q2 are sufficiently large, the band- rate. Accordingly, the video circuit band- the needs of a high -definition receiver. width of the circuit in Fig. 7 can be ex- width in a conventional receiver need not pressed as be substantially greater than 4.2 MHz for BW ---- 1.7/2r RLCL. (2) maximum horizontal resolution of televi- Class A cascode transistor pair Using typical values for V cc, V88, V BEI a,, sion images. To preserve horizontal resolu- and a2, the maximum power dissipated by A widely -used output -driver circuit employ- tion capability in a progressive scan re- Q2 iS ing two transistors in a cascode connection ceiver, any decrease in active horizontal PQ2 MAX = 4.0 X 10 7 X BW scan time must be accompanied by a pro- with inductive shunt peaking is depicted in portional increase in video -circuit band- Fig. 7. Electrical drive and bias require-and the corresponding power dissipated width. Doubling the horizontal scan rate ments for TV picture -tube displays call for by Q1 is

Babcock/Rodda/Wedam: Some power considerations for consumer -type high -definition -television displays 53 Vcc 100 ...... ,__,..:::::-..-_-_*=:.=--4ii-_',...7'- , 1--Er 1-,-iii.:F...i=i'f:7:----t

.....______.. -.i.:F47.::: . , : 7-17iEl; fii --" ._-. .,L,_ .: . - 50 -

:::::::::,::::::.-4 :::.z....:-::=,.::::..i.,.:-:::-.F-4-L----:...ia....1 .7.:...-- _.. ..:_-_-._... 1 -t::.:-::.--,--- Y.- OUTPUT :=.----7.:":.=:--.. -..7.....:.:..7--1:::::.:::=-:...:. L.=.7--....--.-1-::, 4-7-r...-. =2--.717-:=-.-7_::::::-...... -:"..=.--=----:::::7.-.."--:.....:=4=1:=-t-'-...... - ---

-=--,

::_. =-_-1.: _- .- --':---E-17-'f--.='.iLE:if.r_r-.:-. --_-_7E-rii-ai_.-1-:-__;_:ff,.:Z= _ 11, rs-...,-, - 13.:. - ',.. 4 ,-,.. ::: ,;:-.:. ----±,,, , ...--,...,,,:-.= ri ... - = - --_-.--'==':::::::=-.._._--..-.-.---1:.:_:::.,.._---,-,- ::-:-...._.:-±:. __:...7":::::-..-4 .. .;--"-'.:;:'''.: - --=-=',--Z--- i

a) , (..)

---±-n ..------E 10 VEE .i Fig.7. Simplified cascode-driver circuit that has found widespread use in TV If3 receivers. Q2 is a common -base stage that provides a low impedance load on -.. ..--,14 ::.,.. :-/".---i.-,-:-.1==.-..:-E.F.F.F.- _-..-_.-= ..7,.....7 Qi, a common -emitter stage. h) g Tom_. - 0 ...... 1000 ohm is used along with transistors exhibiting gain -bandwidths 1 GHz or great-

...... er at collector currents as high as 100 mA. -"'" -" For example, a 40 -MHz data -display driver capable of 40 volts peak -to -peak - ,:-.--:.,_;..,,,.;---,:,..t.-1_-,F.,-..,z,,,._--;-_!...,T:i--,.-==-:___-._:_---._..=, _ can operate with Vcc = +60 volts and 2 VBB = +6 volts. With V° = 1 /2 ( Vcc VBB -V gg), maximum power dissipated ....:r:-..,..._-_,..,...,._ ...... by Q2 is 1.33 watts, and for the same Vc2, ...... ,:mrnr-..94.....,. .,._ -;_r_.....ol- ...... ,. - -,- ,-,-...... power supplied by the Vcc source is 2.92

. , watts per driver. The power compares favor- , ...... ably with that listed in Table II for a 4.2 - 2 3 5 10 20 MHz -bandwidth television application. Retrace Time - Microseconds However, both transistor costs and output - circuit complexity tend to increase with Fig. 6.Deflection yoke losses as a function of retrace time. At the very short wide -bandwidth data -display applications retrace times used for higher scanning rates, the losses increase rapidly. of the cascode-pair circuit.

Po = 2.44 X10-8X BW. bandwidths necessary for high -definition Active load with feedback Power that must be supplied to the cir- television, because most transistors cannot Calculated power in Table II for the class - cuit by the Vcc voltage source is P vcc = meet the requirements of power, voltage, A cascode circuit is a function of static or 8.43 X l0-7 X BW. high gain -bandwidth, and low collector - quiescent currents and voltages, where the As bandwidth increases, power increases base capacitance. Nevertheless, linear, high - static current depends upon the desired in direct proportion for transistors Q1 and resolution, color data display -tube applica- bandwidth. To reduce power dissipation Q2 and the supply source Vcc. Table II tions requiring less than half the peak -to - and yet maintain a constant bandwidth lists calculated power for multiples of the peak drive of high -definition television have and peak -to -peak output voltage, a reduc- maximuSNTSC video bandwidth of 4.2 used the cascode-pair circuit to achieve tion in quiescent current is required with- MHz. With three identical output driver bandwidths as wide as 40 MHz. To reduce out bandwidth penalty. The active load circuits operating from a common Vcc power, the data display driver circuits oper- driver circuit shown in Fig. 8 represents supply, the total power for Vcc is three ate with Vcc supply voltages less than one such design. times the aforementioned value, and this +100 volts, and output signals are capaci- Essentially, Qi operates like a class -A total power is included in Table II. tively coupled to display -tube cathodes amplifier with collector load resistance RL. With the cascode pair circuit configura- where dc -restoration circuits are employed However, unlike most class -A amplifiers, tion of Fig.7, power dissipated in Q2 to maintain proper cathode bias. To ensure "active load" devices Q2 and D2 are inter- becomes a critical problem at the larger wide bandwidths, RL resistance less than posed between the capacitive loadCLand

54 RCA Engineer 28-5 Sept./Oct 1983 Table II.Cascode-transistor pair output -circuit power requirements. (when w = 0 and Vp = 0), D2 is noncon- Circuit BW (MHz) Poi (W) Poe (W) Pvcc (W) 3 x Pvcc (W) ductive, collector -bias current for Q1is provided via RL and DI, and Q2's emitter 4.2 0.10 1.7 3.5 10.5 bias current flows through RF. The quies- 8.4 0.20 3.4 7.1 21.3 cent current of Q2 is not critical, and by 16.8 0.41 6.7 14.2 42.6 using a large feedback resistance RF, the current can be small. Quiescent current of 33.6 0.82 13.4 28.3 85.0 Q1 is determined by RL and bandwidth requirements. If QI's gain -bandwidth is Table III. Active load output circuit power requirements with V, = 0. large in comparison, circuit bandwidth may be expressed as Circuit BW (MHz) PQI (W) P(22 (W) Pvcc (W) 3 x Pvcc (W) BW = 1/27rRLCp 4.2 1.04 0.20 2.48 7.44 (3) where Cp includes stray wiring capacitance 8.4 2.07 0.20 4.57 13.7 at the collector of Qi and the base of Q2 16.8 4.15 0.20 8.73 26.2 along with collector -base capacitances of 33.6 8.30 0.20 17.1 51.2 Q, and Q2. Power dissipated as a function of bandwidth is calculated for an output voltage Table IV. Active load output circuit power requirements with Vp= 50 volts. vo = VF? Vp sin cut (4) Circuit BW (MHz) Poi (W) P02 (W) Pvcc (W) 3 x Pvcc (W) where V E2 = Q2's quiescent emitter vol- 4.2 1.40 0.68 3.49 10.5 tage, and Vp and w are the peak ampli- 8.4 2.79 1.19 6.58 19.7 tude and angular frequency of a sinusoidal 16.8 5.58 2.20 12.8 38.3 output signal. Power dissipated in Q1 consists of the 33.6 11.2 4.22 25.1 75.4 sum of static and dynamic power. With typical values, maximum static power is dissipated in Qi when V E2is approxi- V, mately equal to Vcc/2. Dynamic power tends to increase with output signal vol- Vcc tage Vp and signal frequency w. Represen- tative maximum total power in Q1 is calculated as a function of bandwidth and output signal voltage by setting V E-2 = Vcc/2 and w = 27rBW, which yields Po = BW X 2.47 X 10 -7r/ 20) 0 72w 37r2w X (1 Vp X 9.44 X 10-3 (5) OUTPUT v, - Vp2 X 5.05 X 10-'). Power dissipated in Q2 is the sum of static and dynamic power terms. Using typical circuit parameter values, total power in Q2 INPUT as a function of bandwidth and output signal voltage becomes P 02 = 1.99 X 10-1 (1 + Vp BW X 1.21 X 10-8 (6) - Vp2 X 5.04 X 10-6) Fig. 8. Low -power, active -load driver circuit with response limiting parasitic capac- when w = 27rBW and V E2 = Vcc/2. itance Cp. Power dissipation is calculated for a peak -to -peak sinusoidal output Similarly, power supplied by theVcc signal voltage of 2 Vp and signal frequency of w. source includes static and dynamic terms. With typical parameter values and when w = 27rBW and VE-2 = Vcc/2, Vcc power Q1's collector or RL. With fast, positive - w is large andt = 71-12.w, 37r/ 2w), the going output -voltage transitions (when a) diode threshold voltage of D2 introduces a is is large and -7r/ 2o) < t < 7r/ 2(»), D2 is small discontinuity that is minimized by Pvec = 3.97 X 10-1 ( I BW X non-conductive, and the load CL is charged the complementary diode threshold of DI. 1.25 X 10-6 + Vp BW (7) by Q2, which functions like an emitter fol- In addition, a large amount of negative X 1.21 X 1011) lower. With fast, negative -going output - feedback serves to eliminate any visible Results of power calculations for Q1, voltage transitions (when w is large and distortion of the output signal. Q2, and Vccin the active load circuit with 7r/ 20) < t < 37r/ 2a)), D2 is forward Relatively large bandwidths are possible bandwidths that are multiples of 4.2 MHz biased, andCLis discharged byQ. at low quiescent currents with the active are listed in Table III for Vp = 0 and in With each fast transition reversal (when load circuit. For the quiescent condition Table IV for Vp = 50 volts. Values in

Babcock/Rodda/Wedam: Some power considerations for consumer -type high -definition -television displays 55 Table III represent static power or the power required with a picture containing only low -frequency, low -amplitude signal components. Total power is listed in Table IV for a 100 -volt peak -to -peak output signal at the upper frequency limit of the circuit and represents the condition for a picture full of high -contrast, fine detail. Comparing the cascode-transistor pair (Table II) with the active load circuit (Ta- bles III and IV), it will be seen that Vcc power required for a picture containing very little detail is significantly less for the active load circuit. However, nearly the same power is required for a picture full of high -contrast detail. It will also be noted that both transistors in the active -load circuit dissipate substantial power for a highly detailed picture, but only one transistor, Q2, in the cascode-pair circuit must dissipate substantial power. Commonly, for bandwidths in excess of 12 MHz, Active Load Kine Drivers do Authors(leftto right) Babcock, Rodda, and Wedam. not consume less power than class -A amplifiers, but are more complex and expensive. William Babcockreceived his B.S. in Elec- in 1978. He is now the Head of Television Also, the unavoidable high-level feedback trical Engineering from Iowa State Univer- Receiver Systems Research at RCA circuit can degrade the transient behavior sity in 1948. After graduation, he joined the Laboratories. limiting their application to bandwidths Tube Division of RCA, where he worked on Contact him at below 15 MHz. circuit applications of receiving tubes. He RCA Laboratories was manager of the RCA Receiving Tube Princeton, N.J. Applications Laboratory from 1954 until TACNET: 226-2961 1965, when he transferred to the Solid Conclusion State Division. In 1975, he joined the RCA William Roddareceived his B.S. in Electri- The information presented in this paper is Laboratories as a Member of the Technical cal Engineering from Purdue University in Staff. At the Laboratories, he worked on intended to describe the extent and nature 1958 and M.S. in E.E. from the University of deflection and power -supply problems for Pennsylvania in 1965. He joined the Tech- of the problems to be solved on the road consumer -television applications until his nical Staff of RCA Laboratories in 1958 to high-performance TV displays. Itis retirement from RCA Laboratories in May, where his work dealt with acoustical and hoped that it will be helpful to develop 1983. electromechanical system and devices. new circuit approaches and components Since 1975, he has been involved in the to achieve this performance at reasonable Werner Wedam is a native of Austria and design of video circuitry for television received his diploma in Electrical Engi- applications. cost and acceptable reliability. neering from the University of Technology Contact him at Work is continuing in deflection sys- in Vienna. He came to the United States in RCA Laboratories tems, power supplies and video signal cir- 1967 and worked at several consumer Princeton, N.J. cuits, all areas outlined in this paper. The electronics companies before joining RCA TACNET: 226-2280 overall goal is to develop circuits for broad bandwidth and lower power consumption. For more detailed information on the formulas and derivationsused in this References paper, contact the authors. I. C.F. Wheatley, "Design Considerations for Trans', torized Deflection Circuits," IEEE Transactions on Broadcast and TV Receivers (July 1963). 2. Landee, Davis, Albrecht, Electronic Designers' Hand- book, McGraw Hill Book Company, Inc. (1957). 3. W. Hettersheid, N.V. Philips, "Horizontal Deflection Circuits with the BU105-Device Dissipation," Semi- conductor Application Laboratory, Report RNR-2, NN-I2AP-IX (September I%7).

56 RCA Engineer 28-5 Sept./Oct. 1983 D.F. Hakala

Post -molding processing is a unique requirement for VideoDisc

The "wash -tube" portion of VideoDisc manufacturing process is the final touch that protects the disc -stylus interface.

The processing requiredto manufacture a and protects it against aging and environ- mentally -caused failures (Fig. 1). CED VideoDisc does not end with the LOAD DISCS VideoDisc molding operation. Two addi- The disc surface is played with a dia- tional process steps-chemical surface treat- mond stylus and, if the disc surfaceis ment and lubrication-are required to make untreated, both the disc and the stylus will a highly reliable, long-lived product. suffer from wear. To prevent this, a thin The component additives (lubricants, sta- film of lubricant is applied to the disc in bilizers, plasticizers, and process aids) in the final process step before insertion into the disc -formulation compound provide the caddy and packaging (Fig. 2). good molding and release characteristics, but are also potential candidates, as are polyvinyl chloride (PVC) degradation prod- LOAD DISCS TURNOVER ucts, for migration to the surface of the 1 disc. A thin surface film and/or debris can accumulate under certain conditions. These imperfections will raise the stylus from the CHEMICAL TREATMENT SPRAY SIDE 2 surface, thus drastically reducing the signal level. When the carrier level drops enough, the video and audio signals cannot be recovered and extremely poor picture and sound results upon playback through a TV receiver. This phenomenon is known as UNLOAD DISCS carrier distress and occurs on an untreated L disc as an aging, moisture -sensitivity, or temperature -stress problem. A chemical surface treatment stabilizes the disc surface INSERT INTO CADDY

Abstract: The author reviews the VideoDisc chemical surface treatment and lubrication process steps. The chemical SHRINKWRAP CADDY reasons for the treatments are given, and the chemical solutions used are described Moreover, the author discusses the equipment considerations and environmental tests undertaken to prove out the process. UNLOAD DISCS PACKAGE INTO CARTONS

01983 RCA Corporation Final manuscript received June 13. 1983. Reprint RE -28-5-9 Fig. 1. Post -molding process. Fig. 2. Lubrication/packing.

RCA Engineer 28-5 Sept./Oct. 1983 57 - -1 Fig.3. Conveyorlo ading. The surface -treatment -line con- Fig. 4. Spray chamber. The discs are sprayed with hot de - veyor is loaded with VideoDiscs. ionized water to remove surface contaminants.

Chemical surface treatment the existence of a depletion layer of metal - can act as a particle trap as well as cause a ion salts that results from the treatment drop in signal level when the thickness The primary purpose of the treatment pro- process.'.2 Further, Fourier Transform Infra- becomes extreme. cess is the removal and near -surface deple- red Spectroscopy (FTIR) coupled with a The solution flow rate, atomization pres- tion of undesirable organic additives, deg- reflection sample device was used to mon- sure, nozzle geometry, and nozzle oscilla- radation by-products, and metal -salt impur- itor the surface enrichment of certain for- tion rate are optimized for a given line - ities that can migrate to the surface of the mulation additives relative to bulk concen- speed to provide for good oil distribution. disc. Discs are treated in a process sequence trations.3 Indications are that a "native" The solution is filtered directly before atom- as follows: lubricant layer is also removed in the treat- ization. The air used to atomize the solu- 1. Discs are loaded onto conveyor racks ment. Variations in spatial uniformity and tion is provided by a modified compressor (Fig. 3). thickness appear to depend on the press designed to give particle -free air. Commer- cial oil -free compressors, even those for 2. The discs are immersed in a chemical process. The amount of wetting and spread- hospital use, have proven far too dirty for treatment bath containing amine and ing of the lubricant on the surfaces of this application. surface-active components that provide untreated discs varies significantly!' The chemical treatment step has the side benefit The solvent is tested to specifications uniform chemical treatment. of making a more uniform surface that even more stringent than for a reagent - 3. The residual film is removed through a more readily accepts the subsequently ap- grade material. The lubricant consists of series of highly purified, filtered, de - plied lubricant. two species. A silicone of the type ionized water sprays and dip rinses (Fig. 4). CH3 4. A chemical vapor dryer removes the Disc lubrication water film by displacement drying. (CH3)3Si -0 SiI0 - Si (CH3)3 After the chemical treatment operation, 5. The discs are unloaded from the rack. the VideoDisc is loaded on a carrier mount- Because the video and audio signal ampli- ed on a conveyor belt. The disc is carried tudes are so minute (-850 angstroms and into a spray chamber. At this point, a sol- is used to provide the lubricating qualities, -90 angstroms respectively), the fluids com- vent containing a low concentration of while a modified silicone additive is used ing in contact with the disc surface must lubricant is atomized through a spray noz- to enhance uniform oil spreading, even in be particulate- and colloid -free. The water zle directed at the disc (Fig. 5). The disc moist environments. The lubricant mate- must not only be deionized, but also re- leaves the chamber and is automatically rial specifications are very demanding and quires submicron-filtration and colloid -re- turned over and repositioned on the con- the properties measured include the fol- moval steps. veyor. The other side of the disc is then lowing: Process control is achieved by monitor- lubricated in a second spray chamber. The ing the chemical bath concentrations, the conveyor then carries the disc to the next specific gravity; pH in the rinse tanks, the pH in the chem- station, where it is inserted into the caddy. surface tension; The thickness and uniformity of the oil ical vapor dryer (to monitor decomposi- viscosity; tion resulting in acid), and the organic and on the disc are the parameters of prime particulate contaminants in the rinse tanks. importance. Nominal oil thicknesses are in molecular -weight distribution; Surface analysis of plastics is difficult at the range of 200 to 400 angstroms. At trace organic impurities; and best. However, during the development of lower thicknesses, stylus wear can occur. trace inorganic impurities. the process, research based on Secondary At greater thicknesses, the oil does not Ion Mass Spectrometry (SIMS) confirmed conform as well to the disc surface and Control of the oil thickness is monitored

58 RCA Engineer 28-5 Sept./Oct. 1983 Summary The disc -lubricant layer increases stylus life by approximately two orders of magnitude. The incidence of carrier distress (under environmental stress) is reduced approximately two orders of magnitude as a result of the chemical surface treatment (20 to 30 seconds per side versus less than 0.2 seconds per side). Obviously, to make a quality product, both steps are critical. Much effort at VideoDisc Operations and the RCA Laboratories was expended in the development and successful implementation of the operations. Additional developments will bring technological rewards. An improved understanding of disc -surface physics and chemistry, and their relation to formulation and molding process conditions, will result in a more efficient surface treatment and lubrication.

References 1. D.L. Matthies, M.D. Coutts. J.A. LaPata to V.S. Ban. Internal Communication (January 27, 1983). 2. E.M. Botnick, J.A. LaPatai C.W. Magee, D.L. is sprayed on the Matthies, and E.S. Poleniak .to V.S. Ban. Internal Fig.5. Lubrication spray chamber. A dilute solution of lubricant Communication (January 9, 1981) discs. 3. L. Jacobsen, J.R. Preston, Battelle Cplumbus Labo- ratories Progress Reports, Contract on "Development by our use of X-ray fluorescence spectrome- Environmental tests of Defect -Free VideoDiscs,"' (September 1980 to try on a routine basis. January 1981). Post -molding processes are carried out for 4. C.C. Wang. Internal Communications. two major reasons: Equipment considerations 1. reduced dice/stylus frictional wear, and 2. improved stability to extremes of envi- In addition to critical process conditions ronment. and chemical requirements, equipment -design considerations are important to suc- The treatment process was developed to cessful operation of the surface treatment/ meet stringent criteria under a wide va- lubrication process. riety of environmental stresses. Examples Rack design is critical in both protect- include: ing a disc against damage in transport Hot condensation stress (1 hr) through the treatment operations while also High temperature and high humidity(48 allowing effective rinsing and drying. Con- hr) veyors must be constructed so tank contamination is minimized or eliminated. Mate- Low humidity (<15% relativehumidity) rials of construction are, in general, high- High temperature (130°F), andlow tem- grade stainless steel or Teflon to minimize perature (-40°F) contamination. New Orleans Worst Day tests(a 28 - The lubrication -line turnover demands times repeat of a 24 -hour cycle that in- that a delicate product be handled auto- cludes both a 85°F, 95% relative humid- David Hakala joined RCA Picture Tube matically at a high rate of speed. Nozzle Division,asa process development engi- ity environment and a 105°F, 55% rela- design and layout are important in pro- neer, after receiving his PhD in physical ducing a uniform lubricant layer over the tive humidity environment). chemistry from R.P.I. in 1976. After serving After they are stressed, the discs must meet as group leader of the Analytical Labora- disc surface. Safe handling of the solvent tory for two years, he joined VideoDisc necessitates strict grounding requirements all physical specifications (for example, warp Operations as Staff Scientist working on coupled with an automatic vapor -detection/ and acceleration) and playback criteria for material problems. Currently, he is Man- explosion -suppression system. Economics carrier distress, skipping, and video and ager of Chemical & Process Development. He holds one patent and is the author of of the process are assisted by a highly effi- audio signal/noise. These tests are used for process devel- several publications.. cient solvent -recovery system that not only Contact himat: prevents contamination of the environment, opment and periodic process/product au- "SelectaVision" VideoDisc Operations but permits reclamation of an expensive dits, and are not intended as routine quali- Indianapolis, Ind. raw material. ty -control tools. TACNET: 426-3433

Hakala: Post -molding processing is a unique requirement for VideoDisc 59 Pen and Podium Recent RCA technical papers and presentations

To obtain copies of papers, check your library or contact the author or his divisional Technical Publications Administrator (listed on back cover) for a reprint.

Advanced C. Reno Shaped Array Booms-Intl IEEE/APS Technology Laboratories Optical Disc Recording Techiques for Symp., Houston, Tex. (5/24/83) Data Rates Beyond 100 Mb/s-Presented G. Ammon at SPIE 2nd Intl. Symp. on Optical Mass C. ProferalE. Ngai Data Storage, Arlington, Va., and will be Application of Bivariate Interpolation to An Optical Disc Jukebox Mass Memory published in the Proceedings, (6/6-10/83) System-Presented at SPIE 2nd Intl. Antenna -Related Problems-IEEE Trans- actions on Antennas and Propagation Symp. on Optical Mass Data Storage, B. SiryjIA. Litwak Arlington, Va., and will be published in the Proceedings, (6/6-10/83) Evaluation of Erasable Recorder Mate- A. Sheffler rials-Presented at SPIE 2nd Intl. Symp. Beryllium Application for Spacecraft -De- G. Ammon1B. Siryj on Optical Mass Data Storage, Arlington, ployable Solar Array Booms -24th Va., and will be published in the Proceed- AIAA/ASCE/ASME/AHS Structures Conf., Automatic Handling Mechanisms for an ings, (6/6-10/83) Optical Disc Mass Memory System- Lake Tahoe, Nev. (5/2-4/83) Presented at SPIE '83 Technical Sympo- sium & Instrument Exhibit, Los Angeles, M. Stebnisky IA. Smith A. Weinrich Calif., and will be published in the Pro- F. Borgini IS. Sharma RCA Satcom Long Mission Life Space- ceedings, (1/17-21/83) Approaches & Tradeoffs in Optimal craft-NSIA Mission Assurance Confer- Standard Cell Design-Presented at Cus- ence, Los Angeles, Calif. (6/7/83) R. Cheng1B. Griffin1K. Katsumata tom Integrated Circuits Conf., Rochester, J. Welsh (Missile & Surface Radar) N.Y., and was published in the Proceed- Functional Simulation Shortens the Devel- ings, (5/23/83) opment Cycle of a New Computer-Pres- Automated Systems ented at ACM IEEE 20th Design Automa- J. Tower1B. McCarthy tion Conf., Miami, Fla., and published in the H. Elabd (Laboratories) R.E. Cullen1V.E. Furno Proceedings, (6/27/83) High Density Schottky Barrier IRCCD Sen- Multiplex Data Bus Protocol for Military sors for Remote Sensing Applications- Applications-Society of Automotive Engi- A. Feller Presented at CLEO '83, Baltimore, Md., and neers, SAE/AE-9B High Speed Data Bus Testing VLSI Devices-Presented at IEEE published in the Proceedings, Committee Meeting, Dayton, Ohio (7/83) Workshop on Testing, Atlantic City, N.J. (5/17-20/83) (3/30/83) A. EiranovalE. Velez J. Tower1B. McCarthy A Design and Development Standard for M. Levene H. Elabd (Laboratories) TPS-AUTOTESTCON '83, Fort Worth, Optical Disc Media Parameters and Their High Density Schottky Barrier IRCCD Sen- Tex. (11/83) Relationship to Equipment Design-Pre- sors for Remote Sensing Applications- sented at SPIE 2nd Intl. Symp. on Optical Presented at SPIE International Technical K.J. Fandel Mass Data Storage, Arlington, Va., and will Conference, Geneva, Switzerland, and will Involvement in Quality: An Employee Par- be published in Proceedings, (6/6-10/83) be published in the Proceedings, (4/18/83) ticipation Program to Improve Quality and Productivity-Industrial Engineering or H. Li Training and Development Journal, (8/83) A VLSI Modular Architecture Methodology for Realtime Signal Processing Applica- Astro-Electronics N. Meliones1R.P. Percoski tions-Presented at International Work- Mobile Military Automatic Test Equipment shop on Computer Systems Organization, C. An (Co-op) Using Off -the -Shelf Commercial Elec- New Orleans, La., and published in the Design of Lumped Element 20-GHz GaAs tronics-MITRE/ESD Symposium: Mobile Proceedings, (3/29/83) FED Amplifier, MS Thesis, MIT, Cam- Electronics Systems Packaging Sympo- bridge, Mass. (5/83) sium '83, Foxboro, Mass. (5/83) B. McCarthy1H. Elabd (Laboratories) Thin Film Pd2Si Schottky -Barrier IR Detec- R. Gounder tion for SWIR Wavelength-Presented at Advanced Composite Antenna Reflectors International Conference on Metallurgical for Communications Satellites-SAMPE Commercial Communications Coatings, San Diego, Calif. (4/18-22/83) Journal (7/83) Systems Division

R. McMahon 1H. Li J. Howard R.K. Baldock The Modeling and Simulation of a Pro- A Statistical Canting Angle Model Using TCR-10-A Cassette Sequencer for the grammable Signal Processor-Presented Horizontal Wind Energy Spectra- Hawkeye System-Society of Broadcast at 14th Pittsburgh Modeling & Simulation Melecon, Athens, Greece (5/83) Engineers, Louisville Chapter, (5/18/83) Conference, University of Pittsburgh, Pitts- burgh, Pa., and will be published in the C. ProferalE. Ngai F. Davenport Proceedings, (4/21-22/83) Antenna Range Parallax Correction for Hawkeye-The PAL Recording Camera

60 RCA Engineer 28-5 Sept./Oct. 1983 by Means of a UV Reflectometer-RCA System-IRECON International, Sydney, D. Herzog Review, Vol. 44 (3/83) Australia (9/83) Optical Disc Utilized as a Data Storage System for Reconnaissance Application- R.N. Hurst Presented National Aerospace Electronics P.G. Huggett1K. Frick1H.W. Lehmann Why I and Q?-NAB, RCA Literature Conference, Dayton, Ohio, published Development of Silver Sensitized Germa- Handouts (4/10/83) NAECON Conference Notes (5/17-19/83) nium Selenide Photoresist by Reactive Sputter Etching in SF6-Appl. Phys. Lett., E.H. Mayberry T.N. Nguyen1D.B. Wolfe Vol. 42, No. 7 (4/1/83) Expectations vs. Realities of Circularly Steady State NOdal Thermal Analysis for Polarized Panel Antennas for TV Broad- Printed Wiring Assemblies-Presented 8th L. Jastrzebski1A.C. Ipri1J.F. Corboy casting-IEEE Broadcast Symposium, Annual (Applicon) Users Group Meeting, Device Characterization on Monocrystal- Washington, D.C. (9/22/83) Dallas, Tex. (5/8-12/83) line Silicon Grown over Si02 by the ELO (Epitaxial Lateral Overgrowth) Process- J.F. Monahan IEEE Electron Device Letters, Vol. EDL-4, A Fully Automatic Portable Production Laboratories No. 2 (2/83) Camera-IRECON International, Sydney, W.E. Babcock1W.F. Wedam Australia (9/83) M. Kumar1S.N. Subbarao Practical Considerations in the Design of T.J. MennalHo-Chung Huang Horizontal Deflection Systems for High - C.R. Thompson Monolithic GaAs Interdigitated Couplers- Analog Component VTRs for 625 Line Definition Television Displays-Presented at the International Conference on Consu- IEEE Transactions on Microwave Theory Systems-Montreux Expo, Switzerland and Techniques, Vol. 31, No. 1 (1/83) (5/28/83) mer Electronics, Chicago, III. (6/8-10/83) D. Baeriswyl1G. Harbeke I. Ladany1A.N. Dholakia H. Kiess1E. Meier1W. Meyer Wedge Coupling of Lasers into Multimode Consumer Electronics Optical Transitions in Oriented Poly- Fibers-Reprinted from Applied Optics, acetylene-Physica 1178 & 1188 (1983) Vol. 22, p. 960 (4/1/83) B.B. Dasgupta Theory of Large Angle Deflection of Elec- D. Botez1J.C. Connolly I. Ladany1D.P. Marinelli trons in the Magnetic Field Inside a Tele- Crystal Growth of Mode -Stabilized Semi- Ohmic Contacts for Laser Diodes-RCA vision Tube-RCA Review, Vol. 43 (9/82) conductor Diode Lasers by Liquid:Phase Review, Vol. 44 (3/83) Epitaxy-RCA Review, Vol. 44 (3/83) B.B. Dasgupta J.S. Maa1J.J. O'Neill Calculation of Inductance of the Horizontal D.J. Channin, Sr.1D. Botez Reactive Ion Etching of Al and Al -Si Films Coil of a Magnetic Deflection Yoke-IEEE C.C. Neil1J.C. Connolly1D.W. Bechtle with CCI4, N2, and BCI3 Mixtures-J. Vac. Transactions on Con. Elec., Vol. CE28 Modulation Characteristics of Constricted Sci. Technol., A 1 (2) (4-6/83) (8/82) Double-Heterojunction AIGaAs Laser Diodes-Journal of Lightwave Technology, C.W. Magee Vol. LT -1, No. 1 (3/83) B.B. Dasgupta Analysis of Hydrogen and Deuterium by Effect of Finite Coil Thickness in a Mag- R.V. D'Aiello1P.H. Robinson1E.A. Miller Secondary Ion Mass Spectrometry as netic Delfection System-Journal of App- Applied to Fusion Technology-J. Vac. lied Physics, Vol. 54 (3/83) The Growth and Characterization of Epi- Sci, Technol., A 1 (2) (4-6/83) taxial Solar Cells on Resolidified Metallur- gical -Grade Silicon-RCA Review, Vol. 44 (3/83) C.W. Magee Government Sputtering of Organic Molecules-Interna- D.A. deWolf tional Journal of Mass Spectrometry and Communications Systems A Random -Motion Model of Fluctuations Ion Physics, Vol. 49 (1983) in a Nearly Transparent Medium-Radio R. McEachern Science, Vol. 18, No. 2 (3-4/83) G.H. Olsen IT.J. Zamerowski Intruder Detection by Means of Small N.J. DiGiuseppi Chirped Radars-Presented Fourth Sen- M.T. Duffy1J.F. Corboy1R.A. Soltis 1.3-µm InGaAsP Continuous -Wave Lasers sor Tech Symposium, Vicksburg, Mich. Reactive Sputter Etching of Dielectrics- Vapor Grown on (311) and (511) InP Sub- (4/25-29/83) RCA Review, Vol. 44 (3/83) strates-J. AppL Phys., Vol. 54, No. 6 (6/83)

D. O'Rourke1A. Bramble (ERADCOM) B.W. Faughnan1J.J. Hanak G.H. Olsen Agile Frequency Synthesizer-Presented Photovoltaically Active P Layers of Amor- Vapour -Phase Epitaxy of GalnAsP-Chap- at Frequency Control Symp., Ft. Mon- phous Silicon-Reprinted from Applied ter 1in GalnAsP Alloy Semiconductors, mouth, N.J., and will be published in the Physics Letters, Vol. 42, No. 8 (4/15/83) published by John Wiley & Sons Ltd. Proceedings, (5/31 /83) (1982) J.J. Hanak 1V. Korsun Optical Stability Studies of a Si:H Solar J.I. Pankove1J.E. Berkeyheiser Cells-Reprinted from Proceedings of the S.J. Kilpatrick1C.W. Magee Government Sixteenth IEEE Photovoltaic Specialists Passivation of GaAs Surfaces-Journal of Systems Division Conference (9/82) Electronic Materials, Vol. 12, No. 2 (1983) G. Harbeke1L. Krausbauer1E.F. Steigmeier H. Barton D. Redfield A.E. Widmer1H.F. Kappert1G. Neugebauer Design to Unit Production Cost-Pre- Incomplete Space -Charge Layers in High -Quality Polysilicon by Amorphous sented IEEE Reliability Group Rome -Utica, Semiconductors-J. Appl. Phys., Vol. 54, N.Y. Section Meeting (5/11/83) Low -Pressure Chemical -Vapor Deposi- tion-Appl. Phys. Lett., Vol. 42 (2/1 /83) No. 1 (5/83) C.D. Fisher Using the Xerox Star-Presented ADPA G. Harbeke1E. Meier1J.R. Sandercock K.S. Reid -Green Tech. Doc. Div., Hampton, Va., publication: M. Tgetgel1M.T. Duffy1R.A. Soltis Games Computers Play-Digital Press Meeting Minutes (5/25/-27/83) Rapid Characterization of Polysilicon Films (10/83)

RCA Engineer 28-5 Sept./Oct. 1983 61 Patents

Astro-Electronics roresonant transformer power supply syn- Berkman, S. I Corboy, J.F. chronized with horizontal Susceptor for rotary disc Strother, J A deflection -4385263 reactor -4386255 Low -distortion detection of pulses super- imposed on an unknown and variable Powell, J.P. Botez, D. Butler, J.K. background signal -4388646 Sensing focus of a color Positive index lateral waveguide semicon- kinescope -4387394 ductor laser -4383320

Commercial Communications Shanley, 2nd, R.L. I Parker, R.P. Botez, D Systems Division Compensated clamping circuit in a video Phase -locked CDH-LOC injection laser signal peaking system -4386369 array -4385389 Banks, A.J. Willis, D.H. Memory conservation method in a pro- Channin, D.J. Television receiver ferroresonant load Liquid crystal lens display grammable ROM sync generator power supply disabling circuit -4390820 system -4386368 system -4385805 Willis, D.H. Chin, D. Henderson, J.G. I Maturo, R.J. Banks, A.J. Remote responsive television receiver fer- Tuning display for a television TV sync generator system for PAL roresonant power supply protection standards -4390892 circuit -4387324 receiver -4390902 Clark, Jr., C.A. Datta, P.I Poliniak, E.S. I Ban, V.S. Self-starting transformer -coupled FET High density information record multivibrators-4390937 Government lubricants -4389441 Communications Systems Colgan, Jr., J J Datta, P. (Poliniak, E.S. Television camera tube assembly and Coyle, P.J. I Crouthamel, M.S. Doped polyphenylene ether lubricant for electrical contact for target Vacuum lamination fixture -4382833 high density information discs -4390579 electrode -4384233 Dieterich, C.B. Hedlund, L.V. I Herzog, D.G. I Putzrath, F.L. Disc record system employing signal Search -mode arrangement for Laboratories redundancy -4382299 VTR -4388657 Altman, T.N. Dischert, R.A. Reitmeier, G.A. Katagi, K. Video disc player with multiple signal re- De -emphasis for digitized composite color Apparatus for angularly scanning memory covery transducers -4386375 television signals -4388638 addresses -4387370 Amantea, R. I Wheatley, Jr., C.F. Ettenberg, M. Transistor with improved second break- Optical recording medium and information Consumer Electronics down capability -4388634 record with indented overcoat -4383311 Dodds, D.L. Angle, R.L. Gibson, W.G. I Christensen, R.M. Electron beam in influencing apparatus Digital control of number of effective rows incorporating vertical beam movement of two-dimensional charge -transfer imager Vertical and horizontal detail signal function -4388602 array -4382267 processor -4386434

George, J.B. I Testin, W.J. Angle, R.L. Harwood, R.E. Phase locked loop tuning control system CCD triple -split gate electrode transversal Method of forming reference flats on including a timed sync activated aft signal filter -4387354 styli -4387540 seeking arrangement -4385315 Arroyo, N.A. I Desai, N.V. I Buchanan, J.F. Henderson, J.G. Maturo, R.H. George, J.B. Method to determine carbon black Carrier detector apparatus useful in a mul- Wired remote control apparatus for a tele- content -4388410 tiband sweep type tuning vision receiver -4386371 system -4387401 Babcock, W.E. lWendt, F.S. Griffis, P.D. Television receiver ferroresonant power Hinn, W. Semiconductor apparatus with integral supply using a two -material magnetizable Automatic kinescope bias control system heat sink tab -4387413 core arrangement -4390819 with digital signal processing -4387405

Key, C.W. Christensen, 2nd, E.W. Barkow, W.H. Hollo, R.B. Appargtus for influencing electron beam Television deflection yoke -4383233 Static discharge device -4385824 movement -4390815 Bell, A.E. Keizer, E.O. Luz, D.W. Willis, D.H. Optical recording medium and information Technique for uniform stylus Television receiver, push-pull inverter, fer- record with tracking aid -4387381 configuration -4388714

62 RCA Engineer 28-5 Sept./Oct. 1983 Kocher, C.P. Abramovich, A. Wine, G.M. Dietz, W.F. Television remote control system for selec- Video disc player having auxiliary vertical Integrated circuit interface in a vertical tively controlling external apparatus synchronizing generator -4387407 sync circuit -4387397 through the ac power line -4386436 Harford, J.R. Leahy, M.F. AFT lockout prevention system -4388649 Calibration device and method for an optical defect scanner -4386850 Missile and Surface Radar Harwood, L.A. IWittmann, E.J. Filter and phase shift circuit for a television Lehmann, H.W. I Frick, K. I Widmer, R.W. Inacker, H.F. I Henderson, E.L. automatic flesh color correction Reactive sputter etching of Temperature compensation of a flux drive system -4385311 aluminum -4387013 gyromagnetic system -4382237 Harwood, L.A. Limberg, A.L. Martinson, L.W. Shanley, 2nd, R.L. Hettiger, J. Adjustable -gain current amplifier for tem- Multi -purpose retimer driver -4387341 Predictably biased dc coupled video sig- perature -independent trimming -4389619 nal peaking control system -4388647 Schelhorn, R.L. Liu, F.C. Structure for mounting a semiconductor Harwood, L.A. Variable peaking control circuit -4384306 chip to a metal core substrate -4383270 Shanley, 2nd, R.L. Hettiger, J. Frequency selective dc coupled video Liu, S. signal control system insensitive to video Method for enhancing electron mobility in signal dc components -4388648 GaAs -4383869 "SelectaVision" Harwood, L.A. Clamping arrangement for a video signal Lock, B.E. VideoDisc Operations peaking system -4386370 Method and apparatus for separating a stamper from a mold -4381964 Amery, J.G. I Wharton, J.H. Video disc systems with plural preempha- Kessler, Jr., S.W. I Reed, R.E. sis/deemphasis networks -4385326 Center gate semiconductor device having Makino, J. pipe cooling means -4386362 Video disc player with a freeze frame Hunter, Jr., R.E. feature -4383276 TV interface rf modulation Malchow, M.E. circuitry -4386377 Automatic gain control arrangement useful Martinelli, R.U. in an fm radio receiver -4385400 Brackelmanns, N.W. I Robinson, P.H. Kelleher, K C High -current, high -voltage semiconductor Video disc player with RFI reduction cir- Mendelson, R.M. devices having a, metallurgical -grade cuit including an AGC amplifier and dual Self -quenching circuit -4382192 substrate -4383268 function peak detector -4385374 Schade. Jr., O.H. O'Mara, K.D. McNeely, M.L. I Rees, H. Amplifier circuits -31263 Method of making a laminated recorded Method for producing injection molded disc -4390487 and centrally apertured disc Wacyk, I.T.I Stewart, R.G. records -31235 Pulse generating circuit using current Pampalone, T.R. source -4386284 Sulphur dioxide cured coatings -4389433 Mehrotra, G.N. Video disc player with selectively enabled Webb, P.P. Pollack, J.D. audio signal expander circuitry -4388654 Avalanche photodiode and method of Carriage translating mechanism for video making same -4383267 disc player -4390978 Nyman, F.R. (Stevens, B.N. I Ekstrom, L. Drying process for video discs -4383961 Rhodes, R N Color filter having vertical color stripes Prusak, J.J. Special Contract Inventors with a nonintegral relationship to CCD Cathode head -4385978 photosensors-4388640 McGinnuss, V.D. Taylor, B.K. ESR analysis of conductive video disc components -4386319 Rosen, A. Video disc player having stylus position Method for fabricating a low loss varactor sensing apparatus -4382292 diode -4381952 Schwarz, H.G. Composite video signal limiter -4384302 Russo, P.M. Double layer liquid crystal device for a dot matrix display -4384763 Solid State Division Video Component Swartz, G.A. Balaban, A.R. (Steckler, S.A. I Fernsler, R.E. and Display Division Electrolytic etch for eliminating shorts and Television receiver high voltage protection shunts in large area amorphous silicon circuit -4389676 Chen, H. solar cells -4385971 Color picture tube having an expanded Balaban, A.R. (Steckler, S.A. focus lens type inline electron gun with an Weber, D.M. I Alleman, R.A. Start-up circuit for a power imroved stigmator-4388553 Method of etching apertures into a contin- supply -4385264 uous moving metallic strip -4389279 Greninger, P.T. Bessolo, J.M. Gillberg, J.E. Color picture tube having an improved Wine, C.M. Watch circuit with oscillator gain expanded focus lens type inline electron Single button control -4385204 control -4387350 gun -4388552

RCA Engineer 28-5 Sept./Oct. 1983 63 J.P. Russell IA.M. Goodman L.K. White D. Meyerhofer Engineering Management Meeting, Phila- L.A. Goodman IJ.M. Neilson Positive -Resist Processing Considerations delphia, Pa. (4/83) The COMFET-A New High Conductance for VLSI Lithography-RCA Review, Vol. MOS-Gated Device-IEEE Electron Device 44 (3/83) N.R. Landry IE.J. Kent Letters, Vol. EDL-4, No. 3 (3/83) Precision Combiner Networks for Phased A.E. Widmer IR. Fehlmann IC.W. Magee Array Antennas-International IEEE/APS H. Schade E.F. Hockings The Post -Hydrogenation of Low -Pressure Symposium, Houston, Tex. (5/26/83) Measuring Intensity Distributions in Elec- Chemical Vapor Deposited Amorphous tron -Beams by Scanning Auger Micro - Silicon-Journal of Non -Crystalline Solids, H.D. Lewis graphing of a-Si:H-J. Vac. Sci. Technol., Vol. 54 (1983) Coordination of Extended Range Air A 1(2) (4-6/83) Defense with AEGIS S -Band Data Link- C.P. Wu F. Kolondra A. Hesser ADPA Fire Control Symposium, Colorado A.K. Sharma W.J.R.I Hoefer Electron -Flood Techniques to Neutralize Springs, Colo. (5/3-4/83) Empirical Expressions for Fin -Line De- Beam Charging During Ion Implantation- sign-IEEE Trans. Microwave Theory and RCA Review, Vol. 44 (3/83) J. Nesbit IV. Stachejko Tech., Vol. MTT-31, No. 4, pp. 350-356 Design of 6 -Bit Diode Phase Shifter Using (4/83) B.S. Yarman H.J. Carlin ANA-Symposium of Computer -Aided A Simplified "Real Frequency" Technique Microwave Engineering, RCA Labs, A.K. Sharma IW.' Hoefer Applied to Broad -Band Multistage Micro- Princeton, N.J. (4/15/83) Propagation in Coupled Unilateral and wave Amplifiers-IEEE Transactions on Bilateral Finlines-IEEE Trans. Microwave Microwave Theory and Techniques, Vol. A.K. McGee Theory and Techniques, Vol. MTT-31, pp. MTT-30, No. 12 (12/82) Beamforming Modeling for Rapid Design 498-502 (6/83) Adjustment-Symposium of Computer - J. Zelez Aided Microwave Engineering, RCA Labs, F. SAnchez Sinencio R. Williams Low -Stress Diamond -Like Carbon Films- Princeton, N.J. (4/15/83) Barrier at the Interface between Amor- J. Vac. Sci. Technol., A 1(2) (4-6/83) phous Silicon and Transparent Conduct- L.C. Pickus ing ()Ades and its Influence on Solar Cell Today's Displays in the Conference of Performance-J. AppL Phys., Vol. 54, No. 5 Tomorrow -30th International Technical (5/83) Missile and Surface Radar Communication Conference, St. Louis, Mo. 30th ITCC Proceedings (5/4/83) H.S. Sommers, Jr. A. Afrashteh Complete Experimental Evaluation of the F. Reifler Carrier Dependence of the Refractive Design and Testing of L -Band Solid State Index from the Frequency Modulation Amplifier-Symposium of Computer -Aided A Vector Wave Equation for Neutrinos- Spectra of Single Mode Injection Lasers- Microwave Engineering, RCA Labs, American Institute of Physics-Journal of Mathematical Physics Appl. Phys. Lett., Vol. 42, No. 11 (6/1/83) Princeton, N.J. (4/15/83)

E.F. Steigmeier H. Auderset J.A. Bauer IP. Bronecke P.S. Sawkar IT.J. Forquer R.P. Perry Optical Scanner for Dust and Defect R. Kolc A. Schelhorn Programmable Modular Signal Proces- Detection-RCA Review, Vol. 44 (3/83) Overview and Applications of Surface sor-A Data Flow Computer System for Mounted Technology-Surface Mounted Real Time Signal Processing -1983 Intl. C. Steinbrlichel Technology, Dallas, Tex. (5/16-17/83) Conference on Parallel Processing (IEEE), Langmuir Probe Measurements on CHF3 Bellaire, Mich. (8/23-26/83) and CF4 Plasmas: The Role of Ions in the F.J. Buckley Reactive Sputter Etching of SiO2 and Si- Software Quality Assurance-Panel Chair- A. Schwarzmann Reprinted from Journal Of The Electro- person, IEEE Second Software Engineer- High Power Diode Time Delay Switch- chemical Society, Vol. 130, No. 3 (3/83) ing Standards Application Workshop, San Symposium of Computer -Aided Microwave Francisco, Calif. (5/17-19/83) Engineering, RCA Labs, Princeton, N.J. J.H. Thomas III (4/15/83) The Use of Backscattered Electron Imag- F.J. Buckley ing with Auger Electron Spectroscopy-J. Software Quality Assurance-IEEE Soft- G.M. Sparks Vac. Sci. Technol., A 1 (2) (4-6/83) ware Quality Assurance, Williamsburg, Va. Ground Clutter Modeling and Detection of (4/18-20/83) Low Speed Targets in the Presence of J.H. Thomas III Ground Clutter Using a Ground Based X-ray Photoelectron Spectroscopy Study R. Clark Radar-U.S. Military Academy, 29th Annual of Hydrogen Plasma Interactions with a Computer Controlled Testing of the Tri-Service Radar Symposium Tin Oxide Surface-Appl. Phys. Lett., Vol. Column Beamformer Assemblies-Sympo- (6/14-15-16/83) 42, No. 9 (5/1/83) sium of Computer -Aided Microwave Engi- neering, RCA Labs, Princeton, N.J. S.A. Steele M. Toda IS Osaka (4/15/83) Fail -Safe System Architectures (Vu- Dual Triangular Bimorph-Driven Motor Graphs)-Data Processing Management with Bidirectional Capability-Reprinted D.C. Drumheller Association, Education Foundation, from 1982 Ultrasonics Symposium The History of the Applicon Users Group- (DPMAEF) Computers in Defense, Applicon User's Group Eighth Annual Torrance, Calif. (6/9-10/83) L.K. White Meeting, Dallas, Tex. (5/9/83) Planarizative Phenomena in Neultilayer T.O. Vinson IT.P. Speas Resist Processing -1983 International W.C. Grubb, Jr. AEGIS Logistics Analysis -18th Annual Symposium on Electron Ion and Pleoton Minicomputers and Microcomputers for Logistics Symposium, Atlanta, Ga. Beams, Los Angeles, Calif. (5/30-6/3/83) Non -Electrical Engineers-Drexel Univer- (8/ 10-11/83) sity, Philadelphia, Pa. (5/20/83) L.K. White A.W. Wainwright Plduarization Properties of Resist and L.E. Kitchen Expanded 10 8 BASIC Capabilities- Polyimide Coatings-J. Electrochem Soc., Application of Your Personal Computer to Applicon User's Group Eighth Annual Vol. 130, No. 7 (1983) Engineering Management Tasks-IEEE Meeting, Dallas, Tex. (5/9/83)

64 RCA Engineer 28-5 Sept./Oct. 1983 R.S.Wang From the Quality End of Software Engi- L.H. Yorinks Logic Analysis and The Tools-N CC neering-ASQC Meeting, Philadelphia, Pa. Automated Testing and Alignment of National Computer Conference, ACM (5/19/83) Modern Phased Array Antennas-Seminar Software Engineering Symposium, on Modern Phased Array Antenna Tech- Anaheim, Calif., NCC Proceedings L.H. Yorinks nology, UCLA, Calif. (5/17/83) Automatic Alignment of a Low Sidelobe Phased Array Antenna-Symposium of M.L. Weisbein Computer -Aided Microwave Engineering, I'd Rather Be Programming, or A View RCA Labs, Princeton, N.J. (4/15/83)

Engineering News and Highlights

Andrews is Director of ATL Terrano is Moss named Technical Education Administrator Information Systems Manager Dr. Ronald A. Andrews has been appointed Director of the Advanced Technology Labo- Bob Terrano recently joined RCA as an Gerry Moss recently joined RCA as Man- ratories of RCA's Government Systems Di- Administrator with the Corporate Engineer- ager of Technical Information Systems in vision. He is responsible for all activities of ing Education staff, located at the RCA Tech- the Engineering Information activity located the organization, which develops technol- nical Excellence Center in Princeton, N.J. at the RCA Technical Excellence Center in ogies in computer systems, applied phys- He will be a part of that activity's efforts to Princeton, N.J. She is responsible for pub- ics, solid-state circuits, electro-optics, sig- create and promote useful videotape -based lishing the RCA Technical Abstracts and nal processing and systems development. technical courses. He is an experienced maintaining the Technical Abstracts Data- Before joining RCA, Dr. Andrews served educator and engineer. Most recently, he base. Mrs. Moss will be working with mem- in systems engineering and technical engi- was Director, Technical Education, for the bers of the RCA library network to expand neering management positions at Xerox New Jersey Department of Education Di- interlibrary cooperation. She will draw on Corp.'s Webster, N.Y. facility. Earlier, he was vision of Vocational Education and Career her extensive experience as an information Branch Head for Optical Physics and Laser Preparation. Mr. Terrano received a B.S. in specialist with major corporations and uni- Interactions at the Naval Research Labora- Industrial Engineering from the New Jersey versities. Her education includes an M.L.S. tory, Washington, D.C. Institute of Technology in 1972, and an M.A. in Information Science, a B.S. in Chemistry, Author of about 30 articles in American in Education, Jersey City State College in and an A.A. in Computer Science. Physical Society and Institute of Electrical 1976. Contact her at: and Electronics (IEEE) Journals, Dr. Contact him at RCA Technical Information Systems Andrews is a fellow of the American Phys- RCA Corporate Engineering Education Princeton, N.J. ical Society and the Optical Society of Amer- Princeton, N.J. TACNET: 226-2410 ica, as well as senior member of the IEEE. TACNET: 226-2149 He also is a member of the Phi Beta Kappa and Sigma Xi honorary societies. Dr. Andrews received bachelor's and doc- RCA elects Gordon, to whom he will report. In this capacity, Mr. tor's degrees in physics from Wayne State Vice -President, Licensing Gordon will have overall responsibility for University, and a master's degree from the company's worldwide licensing activi- Massachusetts Institute of Technology as Election of Allan D. Gordon as Vice -Presi- ties. He succeeds Stephen S. Barone who a part of the Sloan Fellows Program. He dent, Licensing, for RCA Corporation, was plans to retire by year-end. holds several patents in laser physics and announced by William C. Hittinger, Execu- During the past 11 years, Mr. Gordon xerography. tive Vice -President, Corporate Technology, has held several key posts in RCA's Licens-

RCA Engineer 28-5 Sept./Oct. 1983 65 ing activity. Recently, he had been Staff Perry C. Olsen, Director, Project Engineer- Video Component Vice -President, Licensing, with responsibil- ing, announces his organization as follows: and Display Division ity for all of the company's domestic and Robert D. Altmanshofer, Manager, Engineer- international licensing activities. ing -Juarez; Eldon L. Batz, Manager, Resi- Charles A. Quinn, Division Vice -President Mr. Gordon joined RCA in 1950, and sub- dent Engineering; Elmer L. Cosgrove, Man- and General Manager, Video Component sequently served in a series of manage- ager, Engineering Services; Paul E. Crook - and Display Division, announces the appoint- ment assignments in patents and licensing shanks, Manager, Project Engineering; ment of John M. Ratay as Division Vice - in the United States and Japan. Mr. Gordon James C. Marsh, Jr., Manager, Project Engi- President, Manufacturing. was graduated from the University of Mich- neering; and Paul C. Wilmarth, Manager, igan in 1950 with a B.S. in Electrical Engi- Project Engineering. neering. Richard A. Sunshine, Director, Mechanical Promotions Design Engineering, announces his organization as follows: Melvin W. Garlotte, Man- Matthew A. Owen was promoted from Mem- ager, Mechanical Engineering -Instruments; ber, Technical Staff, to Section Manager, Roger D. Sandefer, Manager, Design Draft- Quality & Reliability Assurance, High Speed ing; James B. Waldron, Manager, Mechan- Bi-Polar IC at the Solid State Division. Staff announcements ical Engineering -Chassis and Sub -Assem- bly; and Richard A. Sunshine, Acting Man- Sheldon Gottesfeld was promoted from Mem- ager, Computer -Aided Design Systems. ber, Technical Staff, to Section Manager, Reliability Engineering. Gary A. Gerhold, Plant Manager, Indiana- Consumer Electronics polis Components Plant, announces his organization as follows: Elliott N. Fuldauer, James E. Carnes, Division Vice -President, Manager, Materials; James P. Gallagher, Engineering, announces hIs organization Manager, Plant Financial Operations; Aldo as follows: Tom W. Branton, Manager, Pro- R. Neyman, Manager, Operations -Compo- Professional activities jection Project Engineering; Larry A. Coch- nents; E. Rene Parks, Manager, Industrial ran, Director, Signal Systems and Monitor Relations, CED-Indianapolis; Henry L. Operations; Jack S. Puhrer, Director, New Slusher, Manager, Facilities Services-CED Products Laboratory; Eugene Lemke, Staff Indianapolis; JB Thomas, Manager, Opera- Inman receives Technical Coordinator; James A. McDonald, tions -Plastics; and Gary A. Gerhold, Acting ASNE Gold Medal Director, Display Systems Engineering; Manager, Plant Quality Control. Perry C. Olsen, Director, Project Engineer- ing; Richard A. Sunshine, Director, Mechan- Aldo R. Neyman, Manager, Manufacturing, ical Design Engineering; arid Willard M. announces his organization as follows: Paul Workman, Director, VideoDisc Player Engi- G. England, Superintendent, Manufacturing neering. Operations; John 0. Greene, Manager, Test Engineering and Construction; William E. Tom W. Branton, Manager, Projection Pro- Hall, Superintendent, Manufacturing Oper- ject Engineering, announces his organiza- ations; and Donald V. Temple, Manager, tion as follows: James J. Kopczynski, Man- Process Engineering. ager, Project Engineering. Henry L. Slusher, Manager, Facilities Ser- Larry A. Cochran, Director, Signal Systems vices-CED Indianapolis, announces his or- and Monitor Operations, announces his organization as follows: James C. Wood, Man- ganization as follows: Roger W. Fitch, Man- ager, Facilities Engineering Projects; and ager, Component Engineering; William A. Royal E. Secor, Manager, Facilities and Serv- Inman (lett) with Rear Admiral Wayne E. Meyer Lagoni, Manager, Signal Processing; Ron- ices. ald R. Norley, Manager, Taiwan Coordina- tion and Monitor Design; Robert P. Parker, JB Thomas, Manager, Operations -Plastics, Bryce D. Inman, Manager, Advanced Radar Manager, RE Systems; John F. Teskey, Man- announces his organization as follows: Wil- Development, Missile and Surface Radar, ager, Digital Tuning Systems; and Robert liam B. Craig, Superintendent, Manufactur- received the Gold Medal Award from the P. Parker, Acting Manager, Advanced Tuner ing Operations; Hank A. Hietberg, Manager, American Society of Naval Engineers at Development. Plant Maintenance; Douglas J. McGinnis, their annual national meeting held in Wash- Manager, Process Engineering; Addison E. ington, D.C. on May 6, 1983. Jack S. Fuhrer, Director, New Products Labo- Wilson, Administrator, Plastics Manufactur- The Gold Medal is given for a most sig- ratory, announces his organization as fol- ing Engineering; Richard E. Molyneux, Super- nificant engineering contribution in the field lows: Alfred L. Baker, Manager, Television intendent, Manufacturing Operations; and of Naval Engineering through personal ef- Digital Systems; Billy W. Beyers, Jr., Man- Keith A. Searcy, Manager, Process En- fort, or through direction of others, during ager, Digital Products Development; gineering. or culminating in the five year period end- Charles A. Brombaugh, Manager, Engi- ing in the current year. Mr. Inman was cited, neering Systems; David J. Carlson, Man- Gary A. Gerhold, Acting Manager, Plant in part, "For his visionary leadership in defin- ager, Signal Systems Development RF /IF; Quality Control, announces his organization ing and directing the Navy's first major pro- Aaron C. Cross, Jr., Manager, Advanced as follows: Dennis W. Campbell, Manager, gram in integrating the efforts of a Combat Mechanical Engineering; James L. New- Production Quality Control; John W. Roth - System Agent with ship designers and build- some, Manager, Technology Applications; fuss, Manager, Production Quality Control; ers, and in integrating the first AEGIS Com- and Donald H. Willis, Manager, Digital Sig- and Jill A. Lord, Administrator, Quality Engi- bat System into the first AEGIS guided mis- nal Processing. neering. sile cruiser, USS Ticonderoga (CG 47); for

66 RCA Engineer 28-5 Sept./Oct. 1983 Lancaster plant Technician of the Year Award recipients. From lett to Stewart E. Beshore, James E. Deardorff, Ivan Horning, Mark F. Trax, right: James R. Dowell, Mary Jane McPherson, Joseph J. Gorlaski, Bruce A. Breiner, H. Albert Walschburger, Nhu Van Dang, Ronald L. Dale R. Goodman, Clarence M. Weaver, Jr., John L. Leszczynski, Kennard, Robert G. Sheaffer, George F. Van Cleve. Recipients not in Roy A. Erdman, Stephen C. Forberger, Robert E. Kreider, Robert the picture include David E. Clark, John S. Gagliano, Lee W. Horn, Landis, Jr., David A. Landis, Donald C. Bachman, Denton L. Borry, and Richard L. Wagner.

his perceptive efforts in promulgating the concept of a combat system 'grooming site' to control and reduce the costs, time and risks of shipboard installation and integration of a complex combat system; and for his pioneering excellence in both systems engineering and management of AEGIS Com- bat System development." Mr. Inman, a retired Navy Captain, joined RCA in 1970. While in the Navy, he directed the concept formulation of the phased array radar, the guidance system computer, and the displays for the Advanced Surface Mis- sile System, forerunner of the AEGIS Wea- pon System. Upon his entry into industry, he assumed responsibility for integration of the AEGIS Weapon System intoits ship and development of enhanced capability versions of the AEGIS Weapon System and AN/SPY-1 phased array radar. Additional 1982 Technician of the Year Awardrecipients at the Lancaster plant. From lett to right: Andrew G. Kubala, Scott Stormfeltz, and Allen G. Shappell. Mercuri is elected

Rebecca T. Mercuri, RCA Laboratories, April, May/June and July/August 1982. Au- Pickus appointed Treasurer Princeton, N.J., was elected Vice -President thors from virtually all RCA businesses con- of IEEE Professional of the Delaware Valley Chapter, Acoustical tributed to these issues. Society of America. Communication Society

Milley appointed Associate Leon C. Pickus, Unit Manager, Technical RCA Engineer honored by Editor, PCS Transactions and Management Documentation, in the Na- Society for Technical val Systems Department of Missile and Sur- Communication David E. Milley, of Missile and Surface face Radar, was recently appointed Treas- Radar in Moorestown, has assumed the urer of the IEEE Professional Communica- The RCA Engineer Staff and Editorial Repre- position of Associate Editor of IEEE Trans- tion Society. Mr. Pickus has been a member sentatives received a Certificate of Merit actions on Professional Communication. of the PCS Administrative Committee for from the New York Chapter of the Society The journal, circulated to approximately the past three years and serves on their for Technical Communication "in recogni- 3000 engineers, is published quarterly. Mr. Education Committee as an instructor and tion of exceptional achievement in Techni- Milley is an Associate Member of the Engi- workshop lecturer for the Technically Write cal Communication." The STC recognized neering Staff in the Technical and Man- Program. He is also a Senior Member IEEE overall publications excellence in three con- agement Documentation activity in the Naval and a member of the Society for Technical secutive RCA Engineer issues-March/ Systems Department. Communication.

RCA Engineer 28-5 Sept./Oct. 1983 67 Technical excellence

Taylor receives "SelectaVision" VideoDisc Technical Excellence Award

Byron K. Taylor, Member Engineering Staff, tridge Manufacturing Engineering to meet received the "SelectaVision" VideoDisc Tech- the cost and performance goals of the nical Excellence Award May 23, 1983, by VDC-5 program. The simplification of three virtue of his outstanding creativity, resource- critical parts also offers future opportunity fulness, and proficiency in the development for competitive sourcing and assembly auto- and design of the VDC-5 cartridge. mation. The design of the VDC-5 cartridge Byron was challenged to design a car- brings to eleven the number of patents held tridge that would be rugged, tolerant of play- by Byron and vividly demonstrates his sig- er/arm misalignment, require no adjust- nificant and creative contributions to .the ments, contain a portion of the time -base - VideoDisc developments. correction transducer, use cost effective parts, and sacrifice no performance. Byron met the challenge and, in addition, increased the skipping range and improved the time -base correction. Byron used developments at RCA Labora- tories and many inputs and ideas from Car - J.J. Brandinger (left) with Byron Taylor.

Lysobey receives award The Government Communications Systems candidate coupler configurations. He con- Technical Excellence Award has been ceived and evaluated innovative solutions made to Morris Lysobey of Communica- to the difficult problems of implementing tions Equipment Engineering for his out- impedance matching, fast switching of high standing work in the development of tech- power rf signals, bias and control signals, niques for high -frequency (HF) antenna coup- and power supplies. His resolution of prob- lers. These units enable maximum power lems such as the generation and isolation transfer from a transmitter to antennas of biasing voltages up to 8,000 volts, and whose impedance varies widely with fre- isolation from rf power levels up to 1,000 quency. Anti -jam considerations dictate that watts while both are applied to the pin -di- HF transmitters and antenna systems oper- ode switching devices, exemplified highly ate in frequency -hopping modes at rates creative and professional engineering de- up to several thousand frequency changes sign. per second. Power levels of 1,000 watts GCS is currently mounting a large effort and antenna Q of up to 500 make achieve- to capitalize on the intense interest among ment of the required impedance match at the military services in the increased per- each frequency a formidable task. formance and use of HF communications. Morris has applied his engineering skills Mr. Lysobey's work on agile antenna coup- to this problem. He analyzed various match- lers has contributed substantially to plac- Jim Fayer (left) with Morris Lysobey. ing configurations for several antenna types, ing RCA in a favorable position to achieve evaluated potential switching devices, and our goals in the HF market modeled and analyzed the performance of

68 RCA Engineer 28-5 Sept./Oct. 1983 Editorial Representatives Contact your Editorial Representative at the TACNET numbers listed here to schedule technical papers and announce your professional activities.

Ca blevision Systems TACNET RCA Communications TACNET *John Ovnick Van Nuys, California534-3011 American Communications *Murray Rosenthal Princeton, New Jersey258-4192 Commercial Communications Carolyn Powell Princeton, New Jersey258-4194 Systems Division (CCSD) Global Communications *Dorothy Unger New York, New York323-7348 *Bill Sepich Camden, New Jersey222-2156 Clinton Glenn Meadowlands, Pennsylvania228-6231 RCA Inc. (Canada)

Consumer Electronics (CE) Bob McIntyre Ste Anne de Bellevue514-457-9000

*Eugene Janson Indianapolis, Indiana422-5208 Francis Holt Indianapolis, Indiana422-5217 RCA Laboratories Larry Olson Indianapolis, Indiana422-5117 Byron Taylor Indianapolis, Indiana426-3247 Eva Dukes Princeton, New Jersey226-2882 Don Willis Indianapolis, Indiana422-5883

Corporate Technology RCA Records *Greg Bogantz Indianapolis, Indiana424-6141 *Hans Jenny Princeton, New Jersey226-2111

Government Systems Division (GSD) RCA Service Company Advanced Technology Laboratories *Murray Kaminsky Cherry Hill, New Jersey222-6247 Dick Dombrosky Cherry Hill, New Jersey222-4414 *Merle Pietz Camden, New Jersey222-2161 Ray MacWilliams Cherry Hill, New Jersey222-5986 Ed Master Camden, New Jersey222-2731 Astro-Electronics *Frank Yannotti Princeton, New Jersey229-2544 "SelectaVision" VideoDisc Operations Carol Klarmann Princeton, New Jersey229-2919 *Nelson Crooks Indianapolis, Indiana426-3164 Automated Systems *Paul Seeley Burlington, Massachusetts326-3095 Dale Sherman Burlington, Massachusetts326-3403 Solid State Division (SSD) Government Communications Systems *John Schoen Somerville, New Jersey325-6467 *Dan Tannenbaum Camden, New Jersey 222-3081 Power Devices Thomas Altgilbers Camden, New Jersey222-3351 GSD Staff Harold Ronan Mountaintop, Pennsylvania327-1633 or 327-1827 *Peter Hahn Cherry Hill, New Jersey 222-5319 Integrated Circuits Missile and Surface Radar Dick Morey Palm Beach Gardens, Florida722-1262 *Don Higgs Moorestown, New Jersey224-2836 Sy Silverstein Somerville, New Jersey325-6168 Graham Boose Moorestown, New Jersey224-3680 John Young Findlay, Ohio425-1307 Jack Friedman Moorestown, New Jersey224-2112 Electro-Optics and Power Devices John Grosh Lancaster, Pennsylvania227-2077 National Broadcasting Company (NBC)

*Bob Mausler New York, New York324-4869 Video Component and Display Division

*Ed Madenford Lancaster, Pennsylvania227-3657 Patent Operations Nick Meena Circleville, Ohio432-1228 Jack Nubani Scranton, Pennsylvania329-1499 George Haas Princeton, New Jersey226-2491 J.R. Reece Marion, Indiana427-5566

*Technical Publications Administrators, responsible for review and approval of papers and presentations, are indicated here with asterisks before their names. Wa.thiar-12,_ TODAY'S 14I614 88 In Nagadoches. Tex NEE .TELETEXT TODAY'S LOW 32 in Out ut h. Rine. 50s04. 30s 40s ,50s MENSFRONT 2 WEATHER 9 SPORTS 10 60s MONEY 16 PEOPLE 25 PLRYTIfIE YOUR HOMY 31 FOR SPECIAL GRrE' LIVING 36 YOUR STARS 41 SEE PAGES 30 THE SOAPS 46 .1 DECODER: 70s FUM A GAMES 50 80s NID'S NORMER 55 "PARTNERS" 62 ULY 7.1983 RAIN SNOW April 7. 1983 CREDITS 79 AO INSERT SPACE

Fun&Gams .50 THE SUM WILL COME OUT Most of us give Clark Gable credit for having the last word as Rhett Butler in SOME WITH THE WIND. Who really had the last ANSWER, words and what were VIVIEN LEIGH they' RS SCARLETT YOU HOVE TEM Brian Astle's article on O'HRRA 'AFTER SECONDS :00 ALL, TOMORROW IS ANOTHER DRY NEXT SOME HORSEPLAY page 16 contains specific information about these

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