DOCUMENT RESUME ED 063 733 EM 009 851 AUTHOR Ward, John E. TITLE Present and Proba'lle CATV/Broidband-Communication Technology. INSTITUTION Alfred P. Sloan Foundation, New York, N.Y. REPORT NO ESL-R-449 PUB DATE 5 Jan 72 NOTE 119p.; Repo! of the Sloan Commission on Cable Communications EDRS PRICE MF-$0.65 HC-$6,56 DFSCPIPTORS *Cable Television; Community Antennas; Costs; Information Systems; Media Technology; Telecommunication; Telephone Communication Systems IDENTIFIERS CATV; *Sloan Commission on Cable Communications; Wired City; Wired Nation ABSTRACT The study reports on technlcal and cost factors affecting future growth of Cable TV (CATV) systems and the development of the ',wired nation. Comparisons are made between alternatives for distributing CATV signals and alter.lative prototypes for subscriber home terminals. Multi-cable, augment' channel (with converter), and switched CATV systems are reviewed 1 language aimed at informed laymen. It is concluded that within fi,'e years, a combination of 40 to 60 downstream to-the-subscr. program channels, certain video interconnect services, and slostantial two-way home digital data services can be provided itseveral ways at reasonable cost: from $200 to $500 per subscriber, dc:slding on the type of service,lkIvel of penetration, and costs of 'L;Istalling and maintaining the Appendices discuss interferenu,-: problems in frequency a.ultiplexe 0V transmission over CATV, aad th- characteriztics of two swithed CATV systems. (Author/Mc,' 1 U.S. DEPARTMENT OFHEALTH, EDUCATION Et WELFARE OFFICE OF EDUCATION THIS DOCUMENTHAS BEEN REPRO- DUCED EXACTLY ASRECEIVED FROM THE PERSON ORORGANIZATION OPIG- ((MATING IT POINTS OFVIEW OR OPIN IONS STATED DONOT NECESSARILY REPRESENT OFFICIAL OFtICEOF EDU- CATION POSITION ORPOLICY PRESENT AND PROBABLE C.:ATV/BROADBAND-COMMUNIZATIONTECHNOLOGY John E. Ward June 7, 1971 (Revised January 5, 1972) Report ESL-R-449 A Report Preparedfor the SLOAN COMMISSION ON CABLECOMMUNICATIONS The opinionsexpressed herein and do not reflect are the views ofthe author necessarily theopinions of the of the SloanCommission on Cable members Communications Alfred P. SloanFoundation. or of the ABSTRACT This report presents the results of a btu&%;rformed for the Sloan Commission on Cablo Communications, emphasis el- which v. e technical and eost factors affecting pc.ssible growth of presen;CATV system concepts over the nextseveral dee.ades to encompass addi- tional "wired nation" communicationsfunctions, up to and including point-to-point videophone service.Multi-cable, augmented-channel (converter), and switched CATV systems are reviewed,both from a total channel-count viewpoint, and on the basis oftwo-way capabilities for video and home digital data services. It is concluded that within the next five years, acombination of 40- 1)0 t!ownstream program channels, certain videointerconnect service, and substantial two-way, home digital data services canbe provided in several ways at reasonable cost:$200-$500 per subscriber, de- pendine on the type of service and the level ofpenetration. Switched videophone service would also be feasible, perhaps on a nationalbasi-. by the end of the century, but would escalateper-subscriber costs b-.? a factor of at least 20 or 30, andwould have to be based on a hub rather than a tree network at the subscriber level.. Appendices discuss the inter-channel interferenceproblems in frequency- multiplexed TV transmission, and the detailedcharacteristics of two recently developed switched CATV systems. 4 ACKNOWLEDGMLNTS The study reported herein was supported by two grants tothe Electronic Systems Laboratory, M.I. T.: one from the Sloan Commission on Cable Communications,and the other from the Alfred P. Sloan Foundation. This joint support is gratefully acknowledged. Thanks are also due the large number of people in various organizations who gave freely of their time in providing information: sometimes on more than one occasion. Such peopleandior organizations are credited as appropriate throughout the report. Finally, the contributieem of the others at the Electronic Systems Labs oratory and elsewhere at M.I. T. who participated inthe study are acknowledged. Professor S. Francis Reintjes, Director of ESL, partic. ipated in a number of visits and commission meetings and provided active counsel.Professor James K. Roberge and Mr. Robert G. Rausch of ESL plus Paul J. Fox (graduate student), contributed thebulk of the material on digital technology in Chapter IV anti Appendix D. Thanks are also due Professors Louis D.Smuilin, Wilbur Davenport, and Peter rlias for many stimulai: tag conversations and the reacEng of interim materidl. 4 CONTENTS ABSTRACT Etsa ILL ACKNOWLEDGMENTS iv CONTENTS FIGURES AND TABLES ix I. INTRODUCTION 1-1 SUMMARY AND CONCLUSIONS 2-1 COMPARLSON OF HIGH-CHANNEL-COUNT SYSTEM 3-1 A.Bac kg round 3-1 B.Technical Problems Relating to Channel Usage 3-2 C.Multi-Cable Systems 3-5 1. A Typical Dual.Cabie VHF System 3-5 2.Cost Data 3-5 3.Use of Converters in Multi-Channel Systems 3-7 4. A .1t1ern System Phn 3-8 D.Augmented-Channel Systems 3 -9 1.Characteristics of Present Augmented- Channel Converters 3-9 2.Converter Costs 3-12 3.Ultimate Single-Cable Capacity 3-12 E.Switched Systems 3 -11 1.Introduction 3-14 2.The R ediffus ion Dial -a-Program System 3-15 3.The Amoco DISCADE System 3-IS IV. TWO-WAY CONSIDERATIONS AND SYSTEMS 1 A.Introduction 4-1 11. Upstream Television Channels 4 -I 1.Present Capabilities 4-2 2.Tho Cloudy Future 4-3 CONTENTS (Contd.) C.Digital Channels for Control, Monitoring, and Data Services gm 4-5 I. An Approach to Upstream Communication 4-5 2.Vilma Incorporated 4-8 3.Electronic Industrial Engineering, Inc. 4-9 4. Vicom Industries, Inc. 4.10 5.Privacy Issues on the Cable 4-13 APPENDIX AINTER-CHANNEL INTF.RFERENCE AND THE CABLE-FREQUENCY ALLOCATION PROBLEM A-1 1. IrW.oduction A-I 2.The 6-MHz Television Channel A.3 3.The VHF Channel Alteration A-6 4.Inter-Channel Interference Problems A.11 a. Adjacent-Channel Interference A-10 b.Oscillator Radiation A-13 c. Image Interference A-I4 d.Intermeclulation A-16 e.IF Beats A-17 f .Application of Anti-Interference Rules in UHF-TV A-IS 5.Other Interference Problems Peculiar to Cable A-19 a.Co-Charesel Interference by Broadcast Signals A-19 b.'r:able Interference with Other Services 6. The Cable-Channel Allocation Question A 44 a. A Non-Contiguous Channel Scheme A45 b, A Contiguous Channel Scheme A48 c.Dual Service Class Considerations A-33 APPENDIX 11 REDIFFUSION SWITCHED TV SYSTEM It -I I. INTRODUCTION 11.2 H. BACKGROUND III. THE LIAL.A.PROGRAM SYSTEM 13.5 A. Distribution Cable 13-5 13, The Program Exchange 13.7 vi 4 CONTENTS (Contd.) C.Operational Features asz 13-11 D.Two-Way Capabilities and Potentialities 13- la IV. COST DATA B-I3 A.Exchange Equipment B. Cabling 13-I4 C.Per-Subscriber Distribution Costs B-18 V. ADDENI3VM (December 27, 1971) 1140 APPENDIX C TI1E AMECO DISCADE SWITCHEDTV DISTRIBUTION SYSTEM I. C-1 INTRODUCTION C4 TECHNICAL FEATURES A.Trunks C.3 B. Sub-Trunks C-3 C-4 C.Su'iscribor Switching C-4 D. SubscriberSelector C-6 D1SCADE INSTALLATIONS A.Daly City, California C-8 C.8 B.Disneyworld, Florida C-9 IV. 7WO-WAY CONSIDERATIONS C-9 V. COST DATA C-10 APPENDIX METER READINGVIA TELCO OR POWER LINES D-1 FIGURES 3.1Qwist'Ml Distribution Cable (Rediffusion International, Ltd.) 2122. 3 * 1 6 A-1The NTSC Color Television Channel A-5 A-2Characteristics of Television Systems in Use Throughout the World A-7 A-3Picture-IF Selectivity of Typical Television Receivers A-12 B-1Mechanical Configuration of a 336 x 36 Program Exchange B-11 3-2Signal Distribution in a 336 Subscriber Exchange 13..10 8-3Possible Exchange Layout in Meetum.Density Single Dwelling Area B-15 C-1Amoco DISCADE Distribution System C-5 t..-2Area Distribution Center (ADC) C-7 C-3Possible Amoco DISCADE Layout in same Unit Area used for Rediffusion Analysis C-11 TABLES 3-I Malden Cablevision Channel Selector Guide 3-6 3-11Characteristics of Available Converters 3-11 A-I1937-1940 Television Channel Allocations A-7 A-II Present VHF Television Allocations A-9 A-Ill Prezent VHF, Mid-Band and Super-Band Assignments A-26 A-IV Suggested New Mid- and Super-Band Assignments by M.F. Jeffers A-27 4 CHAPTER I INTRODUCTION The impetus for this report came from the Sloan Commission on Cable Commonications which felt that as part of its deliberations on the desirable future role of broadband cable networks, and how best to achieve that role, it needed a comprehensive review and evaluation of the state-of-the-art in CATY technolon, and expected future capabilities. Of particular interest to the Commission :n connection with sucha review and evaluation were questions such ae the following: 1) Should future broadband systems for home communica- tions services be organized in frequency multiplex tree networks, as in present CATV systems, cr in swited hub networks, as in the telephone system? (This ques- ttort it of course related to the following ones.) 2) What are the prospects for obtaining 40.60, or 80 pro- gram channels, and what are the respective cost expectations? 3) What home data services such as meter reading, push- button banking and/or shopping, and general computer access are (or will be) practical, and what are (or will be) the costs? 4) What is the relation of the future CATV network to the emerging Picturephone service of the Bell System, and would it make technical and economic sense to integrate them and/or replace the limited-resolution 1-MHz Picturephone service with full 4-MHz switched video serv.e? 5) Is nationwide standardization of CAIN systems in the near future a desirable or necessary condition if a oationwide broadband network is the goal? Not all of these questions can of course be answered definitively in a short six-month study, particularly when one is trying to peer 10 or 20 years into the future in an environment of fast-paced technological evolution, and when some of the alternativ a may represent a fair share of the gross national product in terms of required investment.