Antennas, Satellite Broadcasting, and Emergency Preparedness for the Voice of America [1 ed.] 9780309581837

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Antennas, Satellite Broadcasting, and Emergency Preparedness for theVoice of America

A Report Prepared by the Committee on Antennas, Satellite Broadcasting, and Emergency Preparedness for the Voice of America Board on Telecommunications and Computer Applications Commission on Engineering and Technical Systems National Research Council

NATIONAL ACADEMY PRESS Washington, D.C.

1988

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ii

NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance. This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Frank Press is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Robert M.White is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Samuel O. Thier is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy’s purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Frank Press and Dr. Robert M.White are chairman and vice chairman, respectively, of the National Research Council. The project is supported by Contract No. IA-21130-23 between the United States Information Agency and the National Academy of Sciences. Copies available from: Board on Telecommunications and Computer Applications Commission on Engineering and Technical Systems National Research Council 2101 Constitution Avenue, N.W. Washington, D.C. 20418 Printed in the United States of America

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COMMITTEE ON ANTENNAS, SATELLITE BROADCASTING, ANDEMERGENCY PREPAREDNESS FOR THE VOICE OF AMERICA ROBERT P.RAFUSE (Chairman) Senior Staff Lincoln Laboratory Massachusetts Institute of Technology LEWIS S.BILLIG Director for Communications and Theater Systems MITRE Corporation (Retired) BERT COWLAN Telecommunications Consultant DOUGLASS D.CROMBIE Senior Engineering Specialist Aerospace Corporation J.KEITH EDWARDS Assistant Chief Engineer, External Broadcasting British Broadcasting Corporation (Retired) ROBERT S.FORTNER Associate Professor and Director of Radio and Television The George Washington University RAYMOND A.GREENWALD Section Supervisor, Ionospheric PhysicsApplied Physics Laboratory The Johns Hopkins University ROBERT C.HANSEN Consulting Engineer R.C.Hansen, Inc. OTTO W.HOERNIG, JR. Vice President, Business Development Contel ASC JOHN E.KEIGLER Chief Scientist GE Astro-Space Division WILBUR L.PRITCHARD President and Chief Executive Officer SSE Telecom, Inc. THOMAS F.ROGERS President The Sophron Foundation WILLIAM F.UTLAUT Associate Administrator for Telecommunications and Director, Institute for Telecommunication Sciences National Telecommunications and Information Administration ERIC K.WALTON Research Scientist The Ohio State University DANIEL J.FINK (Ex-Officio)*President D.J.Fink Associates, Inc. STAFF Richard B.Marsten, Study Director** John M.Richardson, Study Director*** Lois A.Leak, Administrative Assistant

*Until June 1987, as Chairman, Board on Telecommunications and Computer Applications **Until January 1988 ***From January 1988

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BOARD ON TELECOMMUNICATIONS AND COMPUTER APPLICATIONS CHARLES W.STEPHENS (Chairman) President and Deputy General Manager TRW Electronics & Defense Sector (Retired) DANIEL BELL Henry Ford II Professor of Social Sciences Harvard University HERBERT D.BENINGTON Director of Planning UNISYS Defense Systems CARL J.CONTI Vice President and Group Executive Information Systems and Storage Group IBM Corporation ANTHONY J.DeMARIA Assistant Director of Research for Electronics and Electro-Optics Technology United Technologies Research Center DAVID J.FARBER Professor of Computer and Information Science and Electrical Engineering University of Pennsylvania DONALD M.KUYPER Group Vice President, Business Services GTE Telephone Operating Group JOHN C.McDONALD Vice President and Chief Scientist CONTEL, Inc. ALAN J.PERLIS Eugene Higgins Professor of Computer Science Yale University HENRY M.RIVERA Partner Dow, Lohnes and Albertson IVAN SELIN Chairman of the Board American Management Systems, Inc. ERIC E.SUMNER Vice President, Operations Systems and Network Planning AT&T Bell Laboratories GEORGE L.TURIN Professor of Electrical Engineering University of California, Berkeley KEITH W.UNCAPHER Executive Director, USC Information Sciences Institute and Associate Dean, School of Engineering University of Southern California STAFF John M.Richardson, Director* Richard B.Marsten, Executive Director** Anthony M.Forte, Senior Staff Officer Karen Laughlin, Administrative Coordinator Lois A.Leak, Administrative Assistant

*From January 1988 **Until January 1988

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PREFACE

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PREFACE

This is the interim report of the National Research Council’s (NRC’s) two-year study on antennas, satellite broadcasting, and emergency preparedness for the Voice of America (VOA). The committee conducting this study was established in September 1986 at the request of the Director, Engineering and Technical Operations, VOA, during the preparation of the final report of its predecessor, the Technical Operations Study Committee for the VOA, early in 1986. The objective of the current Committee on Antennas, Satellite Broadcasting, and Emergency Preparedness for the Voice of America (the Committee) is to provide advice, guidance, and recommendations on the VOA’s technical planning and management of its program to modernize, renovate, and expand its broadcast transmission and networking capabilities to support its overseas broadcasting requirements. To achieve this objective the Committee set out to review (1) technical aspects of distributed, electronically controlled antenna arrays and power amplifiers for their application to VOA transmission requirements; (2) backscatter monitoring techniques for assessment of the technical quality of high-frequency (HF) broadcast signals at foreign receiving sites; (3) satellite audio broadcasting as a supplement to, or possible eventual replacement for, high-power HF terrestrial broadcasting over the horizon; and (4) emergency preparedness telecommunications support for studio-to-transmitter links to broadcasting station sites. The Committee was also to review the VOA’s activities in advanced, experimental antenna techniques; planning for satellite broadcasting initiatives; and emergency preparedness telecommunications. The Committee was concerned with affordable, timely applications of advanced techniques appropriate to the VOA’s operating requirements and schedule and budgetary constraints. It was to suggest applications and initiatives consistent with forward planning to ensure continuing technical refreshment of the VOA’s broadcasting system to keep it current with evolving technology. The Committee’s inaugural meeting was held November 6 and 7, 1986. At that meeting the chairman reviewed the 11 principal points of the predecessor committee’s final report (National Research Council, 1986, referenced fully in Chapter 1), and the VOA’s Chief of Planning and Systems Analysis presented a summary of actions under way to respond.

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PREFACE

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Detailed presentations were given by VOA officials on their emergency preparedness program, current engineering activities in the modernization program, broadcast systems network analysis, and procurements for experimental antennas, radio-frequency subsystems, speech processing, and a satellite interconnect system. The Director, VOA Engineering and Technical Operations, addressed the Committee at length on VOA objectives for its engineering and technical operations programs and for the Committee’s work (see Statement of Task, below). A detailed presentation on VOA satellite broadcasting activities in 1986 concluded the presentations. The Committee formed three subcommittees—HF antennas and backscatter monitoring, satellite voice broadcasting, and emergency preparedness—to address the three major thrusts of its work. Five additional meetings of the full Committee were convened prior to preparation of this interim report. Numerous meetings on specific issues were also held by individual subcommittee members and the Director of the NRC’s Board on Telecommunications and Computer Applications (BOTCAP) with officials and members of the technical staffs of the VOA, the Institute for Telecommunication Sciences, the National Aeronautics and Space Administration, the National Communications System, and officials in the United Kingdom, the Federal Republic of Germany, and Finland. In addition to many continuing, detailed, technical presentations by VOA officials and technical staff, the Committee received briefings from MITRE Corporation; the National Communications System; the Federal Emergency Management Agency; Worth Research Associates; the Naval Research Laboratory; and Technology for Communications, International. We also wish to acknowledge the briefings on the new transmitters and the tour and explanation of the broadcasting site facilities and operations provided by the staff of the VOA’s Greenville, N.C. station. The committee concept of the NRC operates successfully and effectively in large part because of committee and staff members’ rapport with, and cooperation and support from, the agency the NRC is advising. From the VOA we appreciate sincerely the contributions and support of Dr. Robert Frese, Director, Engineering and Technical Operations, and Dr. Donald Messer, our VOA program manager, and we are particularly pleased to have had the sustained interest and attention of the Hon. Richard Carlson, Director, VOA, and Mr. Morton Smith, Deputy Director for Modernization. The Committee is particularly grateful to Dr. Richard B.Marsten, Director of BOTCAP, for his counsel, guidance, and contributions throughout this project, and for his continued support as Study Director. Dr. Marsten’s successor, Dr. John M.Richardson, completed the remaining work associated with publication of the report. A committee effort of this scope also imposes extraordinary requirements on the administrative staff. With pleasure, the Committee acknowledges Lois A.Leak for her expert administrative and secretarial support. Finally, as Committee chairman, I express my personal thanks to my colleagues, the Committee members, for their dedicated efforts. Robert P.Rafuse, Chairman Committee on Antennas, Satellite Broadcasting, and Emergency Preparedness for the Voice of America

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CONTENTS

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CONTENTS

STATEMENT OF TASK

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1

EXECUTIVE SUMMARY Some Background Research and Development at the Voice of America High-Frequency Antennas and Propagation Direct Broadcasting by Satellite Emergency Preparedness Telecommunications References

1 1 2 3 5 6 7

2

ANTENNA, PROPAGATION, AND MONITORING CONSIDERATIONS FOR HIGHFREQUENCY BROADCASTING SYSTEMS Systems Modernization Antenna Array System Propagation and Data Sources Monitoring Recommendations References

8 8 9 16 18 21 23

3

SATELLITE DIRECT AUDIO BROADCASTING AND RECEPTION The Context for Development Receiver Availability Effectiveness of High Frequency vs Direct Broadcast Satellite Forecasting Cost-Effectiveness of Services Impact of Large Space Platform Technology Worldwide Use Augmentation of Terrestrial High Frequency Conclusions Recommendations References

24 24 26 27 30 32 33 33 34 35 36

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EMERGENCY PREPAREDNESS TELECOMMUNICATIONS Missions Roles, Responsibilities, and Requirements Disasters and Priorities The Voice of America’s Emergency Preparedness Requirements The Voice of America’s Current Emergency Preparedness Plans Systems Approach to Emergency Planning Awareness of National Security Emergency Preparedness Planning Recommendations References

38 38 40 41 43 48 49 52 53 55

GLOSSARY

56

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STATEMENT OF TASK

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STATEMENT OF TASK

This study has three principal concerns: incorporating phased-array antennas into the Voice of America’s (VOA’s) transmitter sites; the future installation of direct-broadcast satellite (DBS) systems worldwide in the VOA’s broadcasting complex; and emergency preparedness of VOA communications. There are five tasks: 1. Technology and systems review of phased-array antennas at highfrequency (HF). Review modern phased-array antenna techniques and identify those most likely to be applicable in the HF (3 to 26 MHz) band. Consider techniques that can be coordinated among different transmitter site locations for each frequency, and for numbers of frequencies transmitted to audience areas simultaneously from different sites. Consider requirements for overcoming jamming and the possibility of using superpower arrays to counter jamming at particular audience locations. 2. Review techniques for monitoring phased-array and systemperformance. This review will include ground- and space-based techniques, including backscatter monitoring performance of phased arrays, transmitter-antenna combinations, and the ability of the VOA broadcast system to provide satisfactory-quality signals to listeners. It will identify effects of the parameters monitored on system performance, and possible reductions in numbers of frequencies and sites. 3. Review the developing situation in DBS systems. This review will include developments in satellite broadcasting, and in low-cost earth receivers for use in VOA audience countries. Advances in space techniques will be compared with those in terrestrial systems using phased arrays. The committee will attempt to forecast when performance and cost-effectiveness of satellite broadcasting are likely to overtake those of terrestrial HF and will comment on the likely effectiveness of operating the two types of systems in parallel. 4. Review emergency preparedness activities in the VOA. This review will cover the VOA’s activities in response to the President’s directives on emergency mobilization preparedness and national security telecommunications policies, National Security Decision Directives (NSDDs) 47 and 97. The committee will advise what technical operating capabilities the VOA could and could not rely on and how to use that information to meet the requirements of NSDDs 47 and 97. 5. Review applicability of satellite facilities in emergencies. The committee will review the applicability of satellite communications and domestic DBS facilities to provide alternate information sources in emergencies and will advise the VOA on emergency planning and exercising actions that could avoid service outages. Date: October 9, 1986

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EXECUTIVE SUMMARY

1

1 EXECUTIVE SUMMARY

This report is an interim report, scheduled approximately halfway through the Committee’s study. It will be followed by a final report, due in 1989. Some of the study tasks, such as those dealing with DBS-A and emergency preparedness, are essentially complete. Consequently, this constitutes a final report on those efforts. However, a major study effort directed at antenna and propagation considerations is not yet complete and what is reported here is thus, by necessity, somewhat preliminary. SOME BACKGROUND The predecessor committee’s final report (National Research Council, 1986) made several recommendations intended to improve the Voice of America’s (VOA’s) technical and managerial position and result in a more efficient operation. Some of them have been implemented; some have not. The reasons for non- (or partial) implementation of those former recommendations are varied and in many cases outside VOA control; they include lack of a suitable staff or resources, lack of a clear mission direction from outside the VOA, and internal preoccupation with a technical upgrade program made chaotic by recent geopolitical changes and by recent and severe budgetary constraints imposed from without. Considering the situation as it existed two or three years ago and the problems that now exist, it is important to recognize that what was said then was predicated on the continuation of a strong, well-financed upgrade with staffing commensurate with the needs. This Committee is concerned about some of the recent negative press articles that quote from several reports, including that of the predecessor committee, now nearly two years old with much of it history. The present environment in which the VOA must operate is quite different from that of two to four years ago. Consequently, much of the recent criticism appearing in the media is based on statements and conditions that are no longer valid. It is, therefore, either off the mark or unfair. The Committee notes that VOA Engineering has, in the past, attempted to cope with a large increase in procurement authority imposed suddenly on

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EXECUTIVE SUMMARY

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an agency with, at that time, negligible engineering resources. The predecessor committee watched the VOA engineering staff grow in size and competence, a process that does not happen in a day or a week, but over months and years. “Growing pains” are inevitable. Now, however, a relatively mature VOA Office of Engineering and Technical Operations has different problems and is trying to maintain its effectiveness in the midst of unforecast budgetary constraints. Therefore, some of the Committee’s conclusions and recommendations are, to varying degrees, outwardly directed—that is, directed towards other agencies and officials in a position to provide both knowledge and resources for the VOA to prepare for the future while conducting today’s business efficiently. The conclusions and recommendations presented here are abstracted or combined from those appearing in the detailed chapters that follow. Those that the Committee considers most important are summarized here; the others, treating problems of technical detail, are contained in the succeeding chapters. The interested reader should look there for more detail on technologically specific conclusions and recommendations. One recommendation, however, which was made in the predecessor committee’s report (National Research Council, 1986), is so important that the Committee believes it must be emphasized again. Even though it is not stated explicitly elsewhere in this report, it is unanimously arrived at from the Committee’s appreciation of the research and development (R&D) necessary to keep the VOA’s investment in new technlogy and systems current with the evolving state of the art. This matter is discussed in the following section, after which matters specific to this report are summarized. RESEARCH AND DEVELOPMENT AT THE VOICE OF AMERICA The VOA’s modernization program comprises a massive, capital replacement and new construction of terrestrial broadcasting facilities, and a first-time investment in modern systems networking of those facilities. Responsible management of such a massive investment in new technology carries with it a strong need for a continuing R&D program to ensure technical refreshment of the invested facilities so that they evolve with the technological state of the art and the need for another program like the current one is avoided. The predecessor committee’s report (National Research Council, 1986) made this recommendation in the form of an “analysis, experiment, and development (AED)” program; this Committee cannot emphasize strongly enough that such a program, whether it be called AED or R&D, is an essential part of any responsible, technical enterprise that has continuity. The VOA’s modernization program is just such an enterprise, and a very large one. Accordingly, the Committee arrives at the following recommendation: The research and development program of the Voice of Americashould be explicit and visible, not ad hoc.

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EXECUTIVE SUMMARY

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The VOA’s engineering staff does conduct some ad hoc research and development, both in-house and out, under the aegis of advanced planning. They are to be commended for doing so, particularly during the present budgetary chaos. Nevertheless, the Committee continues to be apprehensive about the strength and viability of what remains an ad hoc approach. Some years ago, when the modernization program began, a frenetic staff buildup took place essentially in an information vacuum. Decisions had to be made and commitments undertaken in an environment with little available technological expertise and minimal planning. It was natural to expect mistakes and fortunate that there were so few of them. If the VOA had had a small, dedicated R&D staff operating throughout the “lean years”, much of the chaos of the rapid buildup might have been avoided. Plans would have been made and the technological expertise would have been in place to meet a need for modernization that had been well recognized for many years. As a result, the “wakeup” of the VOA would have been less tumultuous than it was. The Committee reiterates that the VOA should have an organizationally recognized research and development entity. Such a function should be isolated from the day-to-day modernization-program management but be available for technological consultation. Thus is innovation born and the future provided for. There are several ways to create such a function; the Committee will suggest one it deems most efficient: An organization the size of the Voice of America could benefit byhaving not only a Chief Engineer but also a Chief Scientist.

A Chief Scientist’s position would not have direct line management, as does the Chief Engineer’s, but would have an advisory role and would report directly to the Director of the VOA. The staff to support such a person would not be large, but should support both high frequency (HF) and satellite broadcasting R&D. The Chief Scientist’s office would be concerned with the plannning and R&D necessary for the future missions of the VOA, including the currently primary topics of direct broadcasting by satellite and technology advances for HF broadcasting. In addition, that office might serve as the appropriate focus for activities related to World Administrative Radio Conferences. HIGH-FREQUENCY ANTENNAS AND PROPAGATION The topic of high-frequency antennas and propagation is a continuing one. Here, the Committee summarizes tentative and occasionally incomplete conclusions and recommendations, given in more detail in the second chapter of this report. Some of the recommendations of the predecessor committee have been implemented. Some have not. In some cases budgetary and programmatic changes beyond the control of VOA engineering were responsible for the lack of action. What is clear, however, is the growth that has taken place over the past three years—VOA Engineering is now a mature and relatively stable organization. The following paragraphs summarize the principal conclusions and recommendations bearing on HF antennas and propagation. Distributed antenna arrays, in which each sub-array (such as a row or

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EXECUTIVE SUMMARY

4

column of radiating elements), is driven by a separate power amplifier, need to be vigorously investigated, both theoretically and experimentally. In particular, the distributed transmitter, which might consist of a common modulator and power supply with multiple final amplifiers, needs to be developed. Thus the following recommendation is offered: The Voice of America should plan a program to investigatedistributed transmitting arrays and distributed final amplifiertransmitters.

The new, delay-steered, high-gain, experimental transmitting array being completed at Delano, California, presents the VOA with an especially useful laboratory tool. In the process of evaluating the Delano array’s performance, new techniques for acceptance testing and performance monitoring of the next generation of VOA transmitting antennas can be developed. This observation leads to the following recommendation: The Voice of America should use the Delano array as a researchand development tool.

One such use would be to support an advanced-technology measurement study to develop techniques for verifying or improving the theory used in design of new HF antenna systems and to improve acceptance testing techniques for new antennas. One of the outcomes should be the generation of lower-cost acceptance testing methodologies; for example, discovering potential correlations between measured sky-wave patterns and such “ground-truth” data as element-current magnitudes and ground-level field strengths. The Committee commends the VOA for increasing the sophistication of its propagation modeling efforts. Nevertheless, the Committee continues to recommend that the propagation prediction tools known as IONCAP, IONSUM, and VALSUM be used with care. In particular, averaging should be applied, if at all, as late in the model-making process as possible. Furthermore, if at all practicable, data to be averaged should be stored for further study rather than eliminated. In addition, if experimental validations of the predictions are undertaken, for example by using data generated by the Delano array, these should be carried out on a propagation model with minimal averaging. Otherwise, the reasons for agreement with the observations may not be identifiable. At present VOA Engineering has no objective method of determining the strength of its signals, signal-to(noise-plus-interference) ratios, or their correlation with signal quality in intended audience areas. The Committee urges that, together with the establishment of a backscatter monitoring program, the VOA undertake to develop such methods, and that they be automated. The committee offers the following recommendation: The Voice of America should establish a backscatter monitoringprogram. The program should include construction of a prototype

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EXECUTIVE SUMMARY

5

system derived from requirements that the agency develops for anoperational system. Construction should take place preferably ata readily available U.S. site such as Delano, California, wherethe agency has recently installed a new, high-performanceantenna.

DIRECT BROADCASTING BY SATELLITE Direct broadcasting by satellite, a technology first developed and demonstrated by the United States, is technically and operationally mature and within the financial reach of governments, as shown by operational systems established for their countries by the governments of Japan, India, and the Arab states. This technology can provide a reliable, high-quality signal to earth receivers more effectively and economically than does HF. The technology of direct audio broadcasting by satellite (DBS-A) is mature, but there are certain steps the VOA should take to ensure that it is not left behind. In India, the Arab nations, and Japan demonstration experiments in satellite voice broadcasting are already going on in frequency bands internationally authorized for the Broadcasting Satellite Service by the International Telecommunication Union (ITU). In its final report (National Research Council, 1986) the predecessor committee recommended that the VOA seize the initiative of launching a cooperative experiment in DBS-A with India leading, making use of the operational Indian National Satellite (INSAT) for the purpose. This Committee reiterates that recommendation: The Voice of America should initiate contact with India promptly,while it develops a U.S. program in DBS-A. Such a program shouldinclude active participation in developing the U.S. delegationposition for the forthcoming 1988 Space World AdministrativeRadio Conference of the International Telecommunication Union.The program should also include liaison with the receiverindustry, both U.S. and foreign, to define the characteristicsand economics of new DBS-A earth receivers.

To these ends, the Director of the VOA should identify a senior professional, provide that professional a small staff and a moderate budget for both in-house and consultant assistance, and make that person and staff a focus for DBS-A planning, demonstrations, necessary SpaceWARC activities, and receiver industry liaison. This group should be part of the VOA’s R&D entity. Most importantly, since the DBS-A technology and concepts for large-scale, multi-use systems are operationally mature and financially realizable, the Committee urges the VOA to inform the White House, Congress, and the Administrator of the National Aeronautics and Space Administration of the opportunities for the future that it presents.

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EXECUTIVE SUMMARY

6

EMERGENCY PREPAREDNESS TELECOMMUNICATIONS The VOA, operating on a mission statement promulgated over a decade ago by Executive Order 11490, is tasked with the requirement to broadcast in the six primary United Nations languages (namely, English, French, Russian, Chinese, Spanish, and Arabic) during and after a major national emergency. As presented to the Committee, the mission is vague and ill-defined, with many associated, unanswered questions such as: To where? At what time? For what purpose? For how long a period (endurance)? Equipment? Energy resources—fuel, standby power, power from the power grid? Personnel resources? As a designated member of the National Communications System (NCS) and its Committee of Principals the United States Information Agency (USIA) has failed to participate. Thus, emergency preparedness guidance that it should have provided to the VOA has been completely absent. The VOA has conducted an ad hoc, part-time planning operation for emergency preparedness which has had all of the difficulties one would expect from a sideline effort, in spite of the dedication of those who have taken part (in many cases, on their own time). There is a clear need for a decision from the USIA leadership. Either the USIA should formally withdraw from its national security emergency preparedness role and not participate officially, or the USIA should acknowledge the requirement and, if there are staffing problems within the USIA, delegate the job to the VOA. Along with that delegation should come the funding necessary to support the activity. VOA’s own stake in this important activity leads to the following recommendations: The Voice of America should seek designation in its own right asa member of the Committee of Principals of the NationalCommunications System, together with the authority to develop itsown emergency preparedness telecommunications program consistentwith national guidelines established by the NationalCommunications System. The Voice of America should seek approval from the NationalSecurity Council for an up-to-date and sufficiently detailedmission statement for its operations during a national emergency.

The mission and guidelines should provide for those steps necessary to achieve the endurability and survivability that do not currently exist within the VOA’s studio-to-transmitter link facilities or among VOA studios or in VOA provisions for staffing. It must be emphasized that, in real emergencies, power will be unavailable from the power grid. Furthermore, there should be an acknowledgment that endurability and survivability require budgetary decisions. The alternative of maintaining the status quo will result in inability to survive or operate through real emergencies because studio-to-transmitter links, and perhaps even studio capabilities themselves, would not have survived, and because emergency power will not be there to support VOA domestic telecommunications facilities.

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EXECUTIVE SUMMARY 7

REFERENCES

National Research Council. 1986. Modern Audio Broadcasting for the Voice of America 1986–2001. Washington: National Academy Press.

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2 ANTENNA, PROPAGATION, AND MONITORING CONSIDERATIONS FORHIGH-FREQUENCY BROADCASTING SYSTEMS After a brief reference to the systems modernization efforts of the Voice of America (VOA), this chapter addresses the more immediate aspects of the Committee’s Tasks 1 and 2. In particular, the chapter first considers the performance of vertical and horizontal phased antenna arrays in the context of the coverage requirements of the VOA. The chapter then discusses techniques of effective prediction of high-frequency (HF) radio propagation and monitoring of the results. The chapter ends with recommendations on these topics. Inasmuch as this is an interim report of the study, remaining aspects of Tasks 1 and 2 will be covered in the final report. SYSTEMS MODERNIZATION HF systems engineering is concerned principally with the determination and specification of the transmitting facilities required to achieve a designated quality of broadcasting service in a specified reception area. This quality of service will be characterized by certain requirements, such as signal strength, resistance to propagation disturbances, and resistance to jamming. There will also be certain constraints, such as frequency allocations, available transmitting sites, and cost. The task of the HF engineer is to meet the requirements within the constraints. For each service a number of simultaneous transmissions in different frequency bands from different transmitting sites may be necessary. The changes in operating conditions arising from the hourly, daily, seasonal and solar-cycle variations of ionospheric propagation give rise to the possibility that many different combinations of transmissions for each program service may be required to attain an optimum result. This needs to be taken into account in the development of plant specifications. In particular, it will be important to ensure that the flexibility necessary for the scheduling of optimum, operating-frequency bands and antenna configurations is incorporated in the design of new and modernized stations. The system design procedure developed by the VOA identifies the possible contributions from each existing or projected station capable of contributing to the audibility of each language service in its service

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area. Detailed specifications of antenna systems for the new relay stations have been adapted to take account of the results that work. The VOA modernization program recognized that in addition to replacing transmitters the antenna systems at existing sites need to be modernized. In considering the priorities under the existing financial stringencies, attention is drawn to the fact that some of these existing stations are equipped with extremely old-fashioned antennas, such as rhombics, intended for point-to-point communications rather than broadcasting. In other cases the antenna complement appears to lack the flexibility required to adapt to changes in priority that have occurred since the stations were constructed. The VOA is procuring new HF transmitters for its broadcasting stations, operating at 500 kW rather than 250 kW power levels. Although a doubling of station transmitter power from 250 to 500 kW achieves an increase of 3 dB in the received signal, this is only effective in the areas presently served by the (fixed) antennas available at that station. The provision of new types of antennas or the provision of improved steering capabilities for existing antennas is likely to provide larger gains in audibility than would merely replacing transmitters. It should therefore receive a correspondingly higher priority in the program. In this regard, the Committee urges the VOA to continue exploiting the best of the available antenna technology and pursuing the technological development of advanced antenna designs as a longer-term objective. Some of the possibilities available are discussed below. ANTENNA ARRAY SYSTEM The VOA has been acquiring relay station sites that are approximately one mile square on flat ground. Large, horizontal-dipole, curtain-array antennas are then erected, the vertical height of the arrays often being more than 400 feet. Typically, four horizontally polarized radiating elements are used in each “bay” (horizontal segment). Often, only two of the radiating elements at a time are active in a stack. Figures 2–1 and 2–2 show the arrangement of dipole radiating elements and the associated feeder system in a multiband, horizontal-dipole, curtain antenna, as used for high power operation in short-wave broadcasting. The nomenclature conventionally used to describe horizontal-dipole, curtain antennas has been standardized internationally, using the form HR m/n/h, with the following meaning (International Telecommunication Union, 1984): HR:

horizontal dipole curtain antenna with reflector curtain

m/:

number of dipole elements in each row

n/:

number of dipole elements in each stack (one above the other)

h/:

height above ground, in wavelengths, of the bottom row of radiating elements.

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FIGURE 2–1 Connection schematic for curtain array antenna.

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ANTENNA, PROPAGATION, AND MONITORING CONSIDERATIONS FORHIGH-FREQUENCY BROADCASTING SYSTEMS

FIGURE 2–2 Curtain array connections with reflector curtain and antenna mechanical assembly.

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The antenna illustrated is an HR 4/4/h, i.e., four dipoles in each row and four dipoles in each stack. The number of elements employed in each row or stack will be selected to form the required azimuthal and elevation radiation characteristics. The spacing of the folded-dipole radiating elements is about one quarter of a wavelength from the aperiodic reflecting screen and is usually half a wavelength between centers of the elements in each row and in each stack at the design frequency. The illustrations show an idealized feeder arrangement with all radiating elements being fed in phase. Maximum radiation will be in a plane normal to that of the elements. In the practical case the vertical feed lines will usually be constructed between the dipole radiators and the reflecting screen and include transforming and matching sections. Switching, which may well be quite complicated, is usually introduced in the feeders at ground level to slew the beam azimuthally or to change the radiation characteristics in the elevation plane by modifying the phase relationships between the various feed points. Since switching feeder line lengths in the switchyard provides control of the phase of feed to each array element, these arrays may be thought of as “phased” or “scanned.” Some typical examples of azimuth and elevation beamwidths based on the radiation patterns of horizontal dipole antennas over average ground are shown in Tables 2–1 and 2–2. TABLE 2–1 Directional Characteristics of Typical Curtain Arrays (Azimuthal) Type of Pattern

Beamwidth at −6 dB Point (degrees)

Slew Angle (degrees)

Very narrow

±8

±30

Narrow

±12

±3.0

Medium

±17

±30

Wide

±34

±15

NOTE: Any azimuthal pattern may be combined with any elevation pattern.

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TABLE 2–2 Directional Characteristics of Typical Curtain Arrays (Elevation) Broadcast Range

Elevation Angle (degrees) Maximum

Lower −6dB point

Upper −6dB point

Very Long

7

2

12

Long

9

3

15

Long

10

3

18

Medium

12

4

21

Medium/short

17

5

30

Short

21

7

38

Very short

27

8

51

NOTE: Any azimuthal pattern may be combined with any elevation pattern.

Distributed Arrays for the Voice of America At the present time the VOA’s modernization program includes developing a number of new relay sites. While the time schedule for the development of these sites has required the utilization of curtain arrays of conventional design, the VOA has determined that future needs will require transmitting antennas with greater gain, steerability and bandwidth. Currently Technology for Communications, International (TCI) is developing two very large curtain arrays for the VOA that are steerable in azimuth and elevation. These arrays, which are high-band and low-band HR/12/6/0.5 antennas, are being installed at the VOA site in Delano, California to improve the VOA services. All of the currently operating VOA antennas, including the experimental antenna at Delano, are driven by a single, high-power transmitter. Steering of these arrays requires high-power switchyards that are generally complex and costly. With this design approach it is difficult to maintain the highest possible gain while using the available flexibility of beam control. Also, only limited beam and gain configurations are possible. An alternative approach is to use a distributed antenna array in which a separate power amplifier is used to drive each row or column of radiating elements or even each radiating element, thus coupling a “distributed amplifier” with the distributed antenna array. Such arrays allow beam steering in azimuth and elevation to be accomplished electronically at low power levels, allow beamwidth changes, provide graceful degradation, permit on-line power-amplifier maintenance, and avoid losses and other problems of high-power switchyards. The following clear advantages of distributed arrays with electronic steering are realized:

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• Elimination of switchyard real estate, life cycle costs, and power loss • Higher gain for those cases where the entire distributed antenna can be used to produce gain instead of switching off part of a single transmitter antenna • More flexible beam control due to the ease of making rapid and fine beam-position changes, both in elevation and azimuth. In costing a distributed amplifier, it is essential that the concept of a combination modulator and power supply of high efficiency be employed, using, for example, switched-mode techniques, together with multiple final amplifiers located as close as possible to the antenna elements they drive.* For valid cost comparisons of systems using distributed versus monolithic amplifiers it will be important to ensure that the multiple applications and the wide frequency range and steering capabilities of distributed-amplifier arrays be compared with those of an equivalent conventional antenna fed from a single transmitter. The comparison should include the cost of associated feeders and feeder and beam-control switching. Horizontal Arrays An alternative to the curtain antenna is the planar, two-dimensional array horizontally deployed. This array achieves elevation directivity by virtue of its projected vertical aperture normal to the take-off angle. For example, at a 10 degree (from horizontal) direction of radiation (the angle to which the beam is steered) the equivalent vertical height of the array is about 17 percent of the depth of the array on level ground. This concept makes a tradeoff of the curtain antenna with a distribution of antenna elements along the ground. (The extra cost of any additional ground space needed must be balanced against the life-cycle costs of the curtain towers.) The utilization of sloping terrain in such a concept can reduce the amount of real estate required as well as improve the lowelevation-angle performance of the array. The relatively lower power required for each antenna element naturally leads to the concept of installing low-power transmitter units at each antenna element (a distributed amplifier-antenna array). The application of such concepts in the future may provide the VOA with increased performance and flexibility at lower system costs. The engineering evaluation of horizontal arrays depends on the specifics of a given application, inasmuch as tradeoffs are available between properties such as gain, scan angles, and site profiles.

*In modern high power broadcast technology for HF the modulator and power supply are one and the same.

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Wideband Radiating Elements VOA curtain arrays utilize broadband elements; array performance is limited both by element capabilities and by array effects. Wideband elements are essential to control the input impedance of the radiating elements over the two-to-one operating frequency range. By ensuring that the relatively complicated feeding system illustrated in much simplifiedform in Figure 2–1 remains reasonably matched over this range there is a greater probability that the power sharing between elements is maintained and that the specification for maximum allowable voltage standing wave ratio (VSWR) at the transmitter will not be exceeded. The maximum allowable VSWR at the transmitter is usually 2:1. The feeder and switching system introduce their own degradations, emphasizing the need for good impedance characteristics at the antenna over the frequency range. Broadband arrays have been used at higher frequencies in other applications, and some of this technology may be applicable to the VOA HF arrays. For example, it may be feasible to adapt ultra-high frequency (UHF), wideband-element technology to HF. The fundamental impedance and frequency characteristics of various types of radiating elements having the required bandwidths should be studied together with the modifications to those characteristics that occur when such elements are used in arrays. This effort should be oriented to computer modeling (e.g., moment methods) initially, as that allows faster and less expensive “experiments” and is adequate for most of the development process. .

Antenna Measurements The Committee considers it very important for the VOA to develop tests to measure the behavior of their antennas. Such tests fall into two categories: (1) comprehensive evaluation of radiation patterns, impedance, and gain on new types of antennas, such as those to be carried out on the antenna at Delano, and (2) the minimum practical tests to provide proof of performance of installed antennas at full power for acceptance testing. In testing the Delano antenna it is particularly important that the gain be considered. The tests on this antenna should be such that the design process is validated. That is, measurements of absolute gain as a function of azimuth and elevation should be compared with the design values for various slew angles. In particular, phase and amplitude measurements of the current distributions should also be made and compared with the expected distributions. Pattern sidelobe levels provide a sensitive indication of errors in the current distribution. In the event that the measured patterns do not agree with the design values, patterns calculated from the measured current distributions should be compared with the measured patterns. This work should simplify and improve the design of future antennas, especially when slewed. The acceptance testing of newly installed antennas must verify the design maximum gain, the azimuth of the maximum gain, design sidelobe level close to the main beam, and the back-to-front ratio. If the test results agree satisfactorily with the design values it can be concluded

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that the amplitudes and phases of the currents in the radiators conform with the antenna design. If not, antenna readjustment may be indicated. The Committee believes that such tests should be conducted using airborne receiving equipment to measure the radiation from the powered antenna. Airborne measurements have the unique advantage that they are the only method of determining the eventual radiation pattern. The radiation pattern of an HF antenna is formed as a result of reflection by the ground, and it may also be modified by currents flowing in the support structure. Data regarding the gain, accuracy of beam shape, and slew angle, as well as sidelobe level and the amplitude of the radiation both in the minima and to the rear of the antenna, should be available. None of these can be predicted from the amplitudes and phases of the current flowing in the radiating elements. If significant discrepancies between design and actual performance are found, such measurements could be an advantageous method of analysis. A calibrated, screened loop is considered to be a suitable, test antenna. The use of a helicopter with precise position finding would be the most suitable method of conducting these test measurements. A cheaper alternative might be to use a balloon as an airborne platform. PROPAGATION AND DATA SOURCES Propagation predictions form an essential tool in the management of an HF broadcasting system. The data from such predictions will be used to specify the types and operating frequency ranges of the antennas required to fulfill VOA objectives. Data will also be required for the operational scheduling of transmissions. In the first case the whole range of potential operating conditions needs to be reviewed and in the second case specific projections will be prepared for operations some months in advance. The service available to listeners is then compared with that predicted. The reception data obtained can be used to correct anomalies in the predictions or differences between the predicted and actual conditions by making corrective changes in scheduling. Such changes will normally be effected in a time scale of days or weeks, as appropriate. Improved corrective measures, to change the optimum grouping of frequency bands used or transmitting sites employed, can only be determined by having a diagnostic process which relates short-term observations to the long-term forecasts used to prepare schedules. The timing and extent of changes in scheduling to take account of mean daily and seasonal variation can then have a rational scientific basis. The listener reports used currently can only be retrospective and may not be representative of the whole reception area. The Ionospheric Communications Analysis and Prediction Program (IONCAP) is a computer program already used by the VOA. It is considered to be the best available method despite having limitations in its input and output routines. The VOA should consider the possibility of improving the utility of the program by improving those routines, avoiding any changes of substance.

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IONCAP, IONSUM, AND VALSUM IONSUM is a computer program using the output of the IONCAP prediction method to determine the most suitable frequency band and required antenna gain under specific averaged conditions. The acronym stands for IONCAP SUMmary. The analysis procedure in IONSUM, based on the output of the IONCAP prediction method, was developed by the VOA to determine which single-frequency band will be most suitable under “averaged” conditions for a particular service from one transmitter site to a target reception area. The report of the predecessor committee (National Research Council, 1986) criticized IONSUM for excessive averaging and a restriction to the use of a single frequency band for a service to the whole of a reception area. The results from this averaging procedure need to be compared with predictions for a selected range of typical conditions using IONCAP, since typical conditions are not average. It will be necessary to consider the most suitable parameters to be used for optimization. The Committee understands that the VOA recognizes the need to supplement the results from IONSUM with additional data from IONCAP regarding the extremes of ionospheric conditions (for example, at sunspot minimum and maximum) and their statistical distribution, and for individual hours rather than the time-block averages previously used in IONSUM. A newly created computer program known as VALSUM, now in use by VOA Engineering, does deal to some degree with earlier Committee concerns. VALSUM (acronym for VALidation SUMmary) takes results of IONSUM for a particular audience area, ionospheric conditions, and sunspot conditions and calculates required power gain, transmitting antenna gain, and beam illumination requirements for specified signal-to-noise ratios and fading margins. The Committee continues to caution, however, that if averaging is carried out at all, it should be done as late in the model-making process as possible. Effective, nearreal-time, experimental verification of the IONCAP, IONSUM, and VALSUM routines cannot be carried out on highly averaged models. Improved and Advanced Propagation Prediction Techniques The investment in capital plant by the VOA should be accompanied by a parallel investment in improving applications of the available prediction methods to VOA operational requirements. Whatever propagation monitoring methods may be developed, the scheduling of operations, particularly for new or inaccessible audience areas, relies heavily on propagation predictions. An organized and methodical program should be established to improve operational performance by analysis of predictions and measurement results. One potentially important input to verification of prediction methods is the measurement of vertical angle of arrival (AOA) signals in VOA reception zones and, when several propagation modes are present, their

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relative times of arrival. These measurements together provide the basis for unambiguous identification of the propagation mode (or modes) involved. Possible methods for making such measurements include the following: 1. The measurement of relative radio-frequency (RF) phase, averaged over several fading cycles, of the received signal on two or more vertically spaced, omnidirectional antennas, which should give the AOA of the signal when only one mode is present or when one mode is much stronger than all the others combined 2. Frequency modulation (FM) chirp transmissions within the assigned bandwidth 3. The use of normal modulation as a quasi-pseudo-noise (PN) probe. The first two techniques can be used, with suitable processing, to obtain the relative delay and strength of multimode signals at the receiving site. However, they alone cannot provide unambiguous mode identification, because the absolute delay of the dominant mode is not obtained. MONITORING Reception-Zone Monitoring Monitoring of the VOA’s HF signals in the intended audience area is highly desirable for determining the performance of the broadcasting system. To be effective, however, it requires the availability of accurate monitoring facilities, a process for analyzing the acquired data, and a method of comparing the monitoring results with the predicted performance. Comparisons need to be done relatively frequently and mechanisms must be in place to allow weekly corrections of the broadcasting system characteristics (e.g., power, antenna pointing, broadcasting site) if shown to be necessary. The current method of using mailed reports from volunteer listeners in the service area is not satisfactory from the viewpoints of objectivity, accuracy, timeliness, or effectiveness of the analysis and feedback mechanisms. Sophisticated, quantitative measuring and reporting techniques are available. Without the analysis and feedback mechanisms, however, they may be no more effective than the present, subjective system. Thus, it is imperative that the VOA recognize this before implementing more sophisticated monitoring techniques and be prepared to invest in the appropriate resources for using the monitoring data. Conventional signal strength monitors have relatively broad bandwidths, which makes them susceptible to noise and interference at frequencies near the frequency of the VOA transmission being monitored. To avoid this out-of-band contamination narrow-band monitoring of the RF carrier should be implemented to determine the signal strength of the desired signal alone. This information will constitute an important input to long-term predictions of ionospheric propagation. A more useful technique supplements signal-strength measurements with signal-to-noise or signal-to-(noiseplus-interference) ratio data. Even

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more useful is the measurement of received-signal quality. Typically, human monitors can assess signal quality with ease, but it is much more difficult to do this automatically. Automatic or machine assessment appears to be desirable for any large-scale monitoring system, because of the high cost and low availability of human observers as well as the need for automated reporting. By way of illustration, some possible signal-monitoring techniques can be mentioned. Signal-to-(noise-plusinterference) ratio measurements can be added readily to signal-strength measurements by inclusion of a narrowband filter centered on a frequency below the lowest modulation frequency, e.g., on the order of 40 Hz. The output of this filter will be a measure of the noise (or noise plus interference) present. After suitable processing the filter output can be combined with the signal-strength data to provide the required signal strength and signal-tonoise ratio information. Two possible techniques for estimating signal quality automatically are suggested. The first technique involves phase-modulating the carrier of a double-sideband transmission with a long, psuedo-noise (PN) sequence which is known at the receiver. The received sequence is compared with the expected sequence and the error rate is determined. Although this method requires calibration for conversion to subjective signal quality, it has the advantage over the use of a coded subcarrier that the full transmitter power is available for the monitoring measurements. The other method does not require additional modulation. Instead, it requires periodically, at known times, the transmission of a prerecorded voice announcement such as “This is the Voice of America.” At the monitoring receivers linear-predictive-coding (LPC) word-recognition programs in microcomputers determine the appropriate coefficients of the received message, compare them with the known coefficients of the transmitted message, and assess the differences between them. If the received signal is of high quality, the difference parameters will be small. As the quality of the received signal is degraded by noise or interference, the difference parameters increase. Thus, with calibration (which is probably easier to do than in the previous technique) the difference parameters can be used to assess the quality of reception. Word-recognition chips for use in microcomputers are readily available, and it is believed they could be adapted to the application suggested here. No doubt there are other techniques available. The important factors in selecting the technique to be used are (1) objective, automatic measurement without human involvement and (2) availability of output in abbreviated, numerical form that can be transmitted periodically to a central processing facility. These features are offered by both techniques described above. Finally, it would be useful but not essential, that the monitoring equipment be emplaced at U.S. embassies, consulates, or United States Information Agency libraries or other sites located in the intended reception areas. Arrangements then must be made to send data back to the VOA in a timely manner. The service must be available for a few seconds to minutes every day to transmit the data back to the United States. It is also essential, as discussed above, that timely analysis of the data be

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20

performed. Appropriate monitoring equipment should be deployed temporarily at sites separated initially by about 500 km, in order to estimate the area within which monitoring results at one site are representative of those throughout the area. Out-of-Country Monitoring of Voice of America Transmissions In addition to signal monitoring capability within each audience area, the VOA should consider some form of external monitoring. This is an alternative approach to providing information on the spatial footprint of a particular transmission as well as on the ionospheric transmission path through which the transmission reaches its destination. Monitoring of this type can be quite powerful since it provides near real-time information on both the spatial extent of the footprint and the azimuth and elevation angles for optimum transmission. This information can be used to increase the signal strength in the audience area as well as to improve VOA ionospheric prediction models. The disadvantage of external monitoring is that it cannot be used to determine the noise or interference levels within the audience area. Nor will external monitoring fully substitute for feedback from the resident population, which it is VOA’s real mission to reach. Without this feedback it is not possible to say whether a doubling of power or antenna gain will add even one more listener. External monitoring is based on the fact that some of the energy in a transmission is, in addition to being reflected onwards, backscattered toward the transmitting site at each ground hop. In general, the backscattered energy returns to the transmitter along the same propagation path. The returning signal can be analyzed to derive propagation delay as well as horizontal and vertical angles of arrival. It would also be possible to derive appreciable information on the propagation path as well as the spatial extent of the footprint at each ground hop. The approach is most useful for transmissions requiring a single hop. At single-hop ranges there is generally significant power in the backscatter returns as well as a small number of possible paths that can bring the transmission to any given range. The source of the backscatter at any ground hop is roughness in the terrain. Cities in the service area will produce stronger backscatter returns than the surrounding countryside, mountains will scatter more than grasslands, and disturbed water surfaces will scatter more than a calm lake. Consequently, the backscatter image will display appreciable surface variability due to cities, mountains, and other rough terrain features. This variability may be used to calibrate the propagation at any particular time. For each feature in the image as well as for the image as a whole it is possible to determine the range to the feature, its bearing, and the takeoff angle of the transmitted energy reaching that feature. By monitoring the bearing and takeoff angles that are required to bring a transmission into a particular service area, one can confirm or improve the predictions of VOA propagation models. Adjustments in the bearing and takeoff angle of VOA transmitting antennas will improve system performance.

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Ideally, an external monitoring facility should be set up within each country for which a new VOA relay facility is being developed. From this site the monitoring facility could monitor backscatter from each of the listener areas serviced by that relay facility. The monitoring facility could be designed to utilize the transmissions from the local VOA relay facility or it could utilize its own signal source. In the former case, some additional modulation would be required on the VOA signal, or some sophisticated pattern recognition software or hardware would be required at the monitoring site in order to provide range information on the backscatter source. In the latter case, the monitoring site would operate independently of the relay site at frequencies near, but not at, the frequencies transmitted by the relay site. In the event that the monitoring station were to utilize its own transmissions, an average power capability of 1 to 10 kW would probably be required. Any of a variety of designs could be incorporated into a monitoring station. One example is given in the report to the VOA by SRI International (Carpenter et al., 1985). The choice of design should be dependent on the ability of the monitoring system to discern the range, bearing, and elevation-angle footprints of the backscatter returns from each of the ground hops. RECOMMENDATIONS The preceeding material leads the Committee to the recommendations that follow. 1. The VOA should initiate a program to investigate the applicability of distributed amplifier-antenna arrays to VOA transmission requirements, considering the following items: a. Perform computer analyses of the relative merits in beam formation and slewing of individuallydriven radiating elements or groups of elements versus driving the array from a single transmitter. b. Evaluate the relative cost of large, vertical, curtain arrays with individually powered radiating elements or groups of elements on the one hand and with the entire array driven by a single transmitter on the other. c. Initiate development and procurement of a distributed-amplifier transmitter including power supply. Important objectives are the achievement of high efficiency and low cost. d. Design and construct experimental, distributed-array systems of modest transmission capability at some U.S. site. e. Evaluate the operational performance of this experimental configuration with regard to fulfilling VOA requirements and in comparison with existing operational requirements. 2. The VOA should plan and start a computer modeling effort on wideband array elements, with the objective of evaluating elements developed for higher frequencies for use in HF curtain arrays.

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3.

22

The VOA should study the horizontal-array concept for possible future applications. The study program should include the following items as appropriate:

a. Theoretical studies of array slew behavior and element driving-impedance behavior, including mutual coupling as a function of array layout and terrain slope b. Experimental tests of the theoretical results using inexpensive, low-power transmitters and antennas c. Cost tradeoff studies, based on the above results, that compare life-cycle costs of vertical curtain arrays and horizontal arrays. 4.

The VOA should perform an advanced-technology measurement study to develop techniques for verifying (or improving) the theory used in the design of their HF antenna systems, and for acceptance testing of newly installed antennas. 5. The VOA should take the following steps to make use of information available from backscatter observations: a. Develop a set of requirements for an operational backscatter monitoring system. b. Construct a prototype system, preferably at a readily available U.S. site such as Delano, California, where the VOA has recently installed as new, high-performance antenna. c. Implement a test program to evaluate VOA performance enhancements that may be achieved through the utilization of backscatter monitoring data. d. Develop methods for measuring vertical angle of arrival of HF signals from distant transmitters. 6. The VOA should undertake to develop the following capabilities for using the information available from signal-strength observations: a.

Objective, automatic methods for determining the strength of its signals, signal-to-(noise-plusinterference) ratios, and their correlation with the quality of its signals in intended audience areas b. Techniques for processing the measurements so that they can be transmitted regularly from the audience area to a VOA processing facility in a timely manner with little or no human intervention c. Operational methods for processing and analyzing the resulting data so that they can be used for operational decisions and as input data for evaluation and improvement of propagation-prediction techniques. Without the operational use called for in the last point any attempt at improved monitoring will be futile. Reception-zone monitoring to evaluate these methods and techniques could be undertaken at Caribbean sites in conjunction with the new antenna facility at Delano, California.

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REFERENCES Carpenter, G.B., R.P.Basler, E.J.Brackman, G.N.Hagn, J.F.McCarty, G.Smith, and H.E.Stuler. 1985. VOA Worldwide Monitoring Analysis: Task 2—Geographic Offset Monitoring. Final Report. Menlo Park, California: SRI International. International Telecommunication Union. 1984. Radio Regulations. Geneva. National Research Council. 1986. Modern Audio Broadcasting for the Voice of America 1986–2001. Washington: National Academy Press.

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SATELLITE DIRECT AUDIO BROADCASTING AND RECEPTION

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3 SATELLITE DIRECT AUDIO BROADCASTING AND RECEPTION This chapter presents the Voice of America (VOA) with a roadmap for introducing satellite audio broadcasting technology, and the improved services which it allows, into its operations to compensate for many of the transmission and reception limitations of its terrestrial, high-frequency (HF), relay network. The related question of television broadcasting must receive only passing mention at this point, although that medium is an increasingly effective one. There might be merit in assessing the relative emphasis on the two media, but that assessment lies outside the scope of this report for the following reasons. First, the VOA has elected to pursue its informational programs through the audio medium and has not formulated a role for itself in television. Secondly, the Television and Film Service of the United States Information Agency (USIA) is responsible for use of the television medium in the USIA mission. Therefore, analysis of the value of television broadcasting and the various technical opportunities for implementing it would be more properly addressed to units of USIA other than VOA. The topical sections that follow correspond closely to items described in the Statement of Task. A phased introduction of direct audio broadcasting by satellite (DBS-A) is shown to be technologically, economically, and politically feasible, within certain limits that the VOA should recognize in its planning for use of this transmission system. Even though a new generation of receivers for satellite reception is required, they can be produced on a short lead time, and this new transmission system can eventually complement the ongoing modernization of the terrestrial HF facilities. The long-term goal to be addressed is the provision of a global service that offers the promises of international political acceptability, lower cost per channel, excellent reliability and quality, and less vulnerability to interference. THE CONTEXT FOR DEVELOPMENT The development of DBS-A is not merely a question of exploiting technological possibility. HF is currently an accepted form of international broadcasting, with a long history of development and use.

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Introduction of a new satellite service by one or more major international broadcaster(s) will require not only that satellites be put into orbit and receivers designed, manufactured, and marketed, but also that parallel strategies be developed to overcome economic and political obstacles to effective deployment of the system. On the economic side, the development of DBS-A must contend with problems of international debt, trade restrictions, and manufacturer attitudes, which could delay introduction of receivers or keep their prices artificially high for an extended length of time. Deployment of DBS-A as a system directed primarily at developing countries, for instance, must contend with the attitude among Asian manufacturers that their profitability is best assured by concentrating on markets with high income elasticity of demand, which is not the case outside a few countries of the industrial West, Japan, the Pacific rim, and Australia and New Zealand. On the political front, achieving a dedicated DBS-A band allocation for regional and international broadcasting must be made a priority of U.S. delegations to the upcoming Orbit World Administrative Radio Conference (Orbit-WARC). This is essential to gain the cooperation of other countries to accept DBS-A signals into their territories, as they could broadcast their DBS-A programs in turn to yet other countries. This could best be done by pursuing the “common carrier” approach to using satellites, or by some variation of this approach, such as providing broadcast time on transponder capacity leased to the VOA for domestic or regional services. The attitude of the Soviet Union is perhaps most crucial, since the VOA has major audiences there and should continue to develop such audiences. But the opposition of the Soviet government to such a broadcasting system would slow the ability of its people significantly to acquire the necessary technology to receive such signals. Pursuing the opportunities provided by glasnost would seem to be in order. In any event, the VOA could use a space-based broadcasting service to reach most of the audiences of the world while continuing to use HF, as it does today, to reach those remaining, non-cooperative ones. Finally, the VOA should recognize, and adopt policies to address, the fact that both economic and political difficulties for this new system could be ameliorated by its own programming changes. People will seek ways to overcome obstacles to access to technology if they have an incentive to do so. As countries’ domestic services move toward higher-fidelity, very-high frequency (VHF) terrestrial systems and people invest in such technologies as audio-cassette players, portable personal radios, compact-disk players, and video-cassette recorders, their expectations of broadcast signal quality and reliability will increase. This seems to require that the VOA consider supplementing HF with other transmission systems, and DBS-A is an obvious choice. But merely providing news programming already available through other channels may not provide the incentive required for people to invest in the necessary reception technology. The programming must exploit the fidelity potential of the technology and compete well against the other options available. Otherwise, investment in such a system would be a waste of resources. For DBS-A to succeed, then, the context for its development must be

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seriously considered. This context requires that the VOA undertake planning not only on the technological questions of transmission but also on effective means to overcome economic and political obstacles and on programming developments that can create the demand necessary to spur production, purchase, and use of the required receivers. RECEIVER AVAILABILITY The recent study for the USIA by the Academy for Educational Development (Fortner, et al., 1986) addressed technological, economic, and political issues affecting radio receiver populations in various parts of the world, with projections through the turn of the century. In detailed and quantitative terms, the report showed that present receiver populations are very unevenly distributed around the globe because of different economic conditions and national, political regulation. Technically, the receiver characteristics in various regions depend directly on the types of signals locally available, medium wave (MW) and short wave (SW) being dominant, with a much lower quantity of VHF units. With no microwave signals (at the frequencies from 1 to 12 GHz that are efficient for DBS-A purposes) currently available, there are, of course, no microwave receivers. Such receivers are not currently produced because there is no consumer demand, and there is no demand because there are no satellite transmitters delivering quality programming. However, several manufacturers have observed that appropriate receivers could be delivered within only six months of a perceived demand. Thus, the introduction of DBS-A need not be hamstrung by unrealistic requirements that its transmissions be compatible with the existing medium-wave and short-wave receivers, although some countries, where the governments control their publics’ access to international broadcasting receivers, are special cases. The history of frequency-modulation (FM) radio and color television outside the developing world has shown that, when new classes of signals with desired program content are made available, user demand and receiver production expand rapidly to exploit the additional benefits of the new medium. Two possible strategies for the VOA to follow as part of an overall plan for development of DBS-A in spurring development and marketing of inexpensive converters or receivers are (1) to publicize its interest widely in development of prototypes that could then be copied by “low-end”manufacturers and (2) to spur development of such devices by placing an order itself—say, 10,000 to 100,000 units—which could be distributed initially to “prime” the market. These receivers could be used provided that some satellite audio broadcast services were made available in an introductory or auxiliary way, using existing satellites. If such receivers were to cost, say, $300 per unit, comparable to costs estimated by the Communications Satellite Corporation for its DBS-TV receivers, an initial market-priming order of 10,000 would cost $3 million. It could well result in establishing a viable manufacturing business in the U.S. economy in addition to opening the way for DBS-A services for the VOA.

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EFFECTIVENESS OF HIGH FREQUENCY VS DIRECT BROADCAST SATELLITE Rogers (1985, 1987) noted that the limitations of surface-based, HF (short-wave) transmissions are generally well known throughout the community of international, long-distance, audio broadcasters. The following is a partial list of these limitations: 1. Complexity in selecting useful operating frequencies and in reaching international agreements for their specific allocation and use 2. Distance constraints between transmitting and receiving areas because of the geometry of the Earth’s surface and its surrounding ionospheric layers 3. Interference from other short-wave signals, broadcast on the same or nearby frequencies, that are also reflected and scattered by the Earth’s surface and the ionosphere 4. Fading, distortion, and loss of the received signal because of variations in the altitude and charge density of the ionosphere brought about by solar-diurnal, seasonal, storm, and sunspot-cycle effects 5. Interference from commercial and industrial noise emanating from the machinery of expanding industrialization in the receiving areas 6. Intentional interference, i.e., “jamming” from unfriendly transmitters whose intent is deliberately to prevent reception of these signals in particular areas 7. Changes in the transmitter frequency and corresponding, required retuning of the receiver by the listening audience throughout the day, to offset the variations in ionospheric reflection or to counteract jamming 8. Technical complexity and high costs, both for initial acquisition and installation and for continuing operation and maintenance, of the many high-power transmitting stations distributed around the world to achieve the desired audience coverage 9. The utility of overseas repeater sites dependent upon the stability of agreements between the United States and host countries. For the VOA in particular, these general limitations of long-distance, HF broadcasting have several impacts on its modernization program. To increase audience coverage and improve probability of satisfactory reception, additional distant repeater sites located within foreign countries and operating with high-power transmitters are being constructed. The effectiveness of these stations depends upon the availability of many frequencies and upon audience willingness to retune to track VOA broadcasts. Even so, the VOA must accept significant degradations in service quality, reliability, and availability compared to commercial, over-the-air, AM and FM service in the United States. In contrast, a DBS-A service promises widespread and predictable surface-area (audience) coverage and excellent reliability and quality of reception. Offered as a large-capacity, common-carrier, common-user service it should find general acceptance among the countries of the world; also, it would confront any potential jammer with severe political repercussions. With little DBS-A experience to date, this technology’s

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relative effectiveness with respect to terrestrial HF broadcasting is subject to some debate. However, the relevant physical laws for radio-wave propagation, transmitter power, antenna gain, receiver sensitivity, and signal quality are well known; furthermore, there is extensive satellite communications experience at many frequencies from both low- and high-altitude orbits to guide the choice of system parameters for DBS-A service. This experience, together with the current state of space technology, provides a sound basis, both technically and economically, for the phased introduction of DBS-A, initially as a supplement and ultimately (i.e., over the next decade or later) as a replacement for the majority of long-distance, terrestrial HF, broadcasting transmitters. Numerous studies (Bachtell et al., 1985; Horstein, 1985; National Research Council, 1986) have shown that satellite broadcasting in the HF band to achieve compatibility with the existing, short-wave, receiver population would require satellite power levels and antenna diameters that are beyond the current state of the art, as illustrated in Figure 3–1. Similarly, at or near the FM band, 88 to 108 MHz, where millions of receivers already exist, spacesegment antennas of the directivity required for regional coverage need apertures beyond the state of the art for space structures. In addition, the required power density incident on earth would create unacceptable interference with the reuse of certain terrestrial FM and television frequencies and therefore contravene the Radio Regulations of the International Telecommunication Union (ITU). However, satellite system configurations become feasible for audio broadcasting channels at microwave frequencies above 1 GHz. Correspondingly, 2.5 GHz and 12 GHz bands have already been designated by the ITU for satellite broadcasting. At microwave frequencies, the characteristics of the transmission path from space to a receiver at or near the Earth’s surface are entirely determinate (although attenuation through foliage and building walls may have to be included as explained below). This advantage stands in contrast to the fading and interference of terrestrial, HF signals caused by the vagaries of the ionosphere. The only significant variable in the satellite-to-earth transmission path is a frequencydependent attenuation through foliage, building walls, and heavy precipitation, varying from nearly negligible at the end of the ultra-high frequency band (UHF) to high (10 to 20 dB) at 12 GHz. In general, a statistical base must be established to account for such excess attenuation values—values which can be expected to vary with receiver location (e.g., inside or outside of buildings, in desert or tropical regions), season, and climate. The straight-path loss from the satellite to all receivers within the line of sight limited by the Earth’s curvature and rough terrain is virtually constant, unlike the varying reflections of HF waves from an ionosphere whose properties change diurnally and seasonally and which can be seriously disrupted by solar storms. Therefore, a single, fixed frequency can provide continuous service to a given area, freeing the listener from retuning. The service area available for satellite broadcasting is a function of satellite altitude, orbit inclination, and antenna beamwidth. Studies of low- vs. high-altitude orbits (Bachtell et al., 1985; Horstein, 1985) illustrate that two of these orbit classes are the most attractive for

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SATELLITE DIRECT AUDIO BROADCASTING AND RECEPTION

FIGURE 3–1 Relationship between antenna aperture and frequency for various radiation beamwidths. NOTE: Examples of current and projected technology are shown. SOURCE: National Reasearch Council (1986).

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29

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practical communications from satellites because of their long (or continuous) visibility to the service area: the geostationary orbit and the so-called Molniya orbit. The Molniya orbit has been employed extensively by the Soviet Union because of its northern latitude coverage. The geostationary orbit has been found more advantageous in the Western world, including northern Canada and Alaska, because of its freedom from satellite tracking requirements by the earth stations. Lower orbits, such as the eight-hour, near-equatorial, and sun-synchronous orbits studied in these references, have the appeal of lower cost per pound of communications payload into orbit, but their short time in view and multiple frequency demands limit their utility for broadcast service. (The Committee understands that the VOA has further study of particular, eight-hour orbits under way but has not yet reviewed that work.) Accepting the higher cost of launching hardware to geostationary orbit and the greater demand on satellite effective antenna gain, the primary limitation of such orbits is the geometrical constraint in northern- and southern-latitude coverage. This latitude constraint is not significant for the VOA since all 15 of its service areas lie within ±70 degrees of latitude, which is within view of appropriately located geostationary satellite(s). Use of microwave frequencies for satellite broadcasting offers a degree of immunity from intentional interference, i.e., surface jamming. Line-of-sight properties of microwave propagation restrict the influence of interfering transmitters with a 1,000-foot antenna height to a radius of 40 to 50 miles, so that prevention of broadcast reception over large areas involves great cost. It is unlikely that jamming of the satellite uplink would be attempted because the uplink’s characteristics could be designed to be jam resistant. Antijam techniques already used on military satellites employ uplink receiving antennas of high directivity, spread-spectrum modulation, and multiple linear receivers. Furthermore, mutual self interest encourages international compliance with ITU conventions in the use of a large-capacity, common-carrier, common-user system. FORECASTING COST-EFFECTIVENESS OF SERVICES At this time, before any DBS-A system has been defined or procured, the accuracy of cost comparisons between terrestrial HF and satellite broadcasting operations is perforce limited. However, the relative magnitudes can be estimated based on the known history and projections of the VOA and the histories of satellite communications systems already inuse for domestic and international fixed service. Table 3–1 summarizes the capitalization and operating costs of one VOA relay site, one international satellite, and one domestic satellite over a ten-year period. Figures in the terrestrial HF column are based on the current VOA modernization program, ranging from $100 million to $150 million per site for local government fees, civil works architecture and engineering (A&E), and equipment added to the current operations and maintenance budget of $70 million per year, which covers the operation of the equivalent of

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8 1/2 relay sites. Each site contains several transmitters and antennas. Figures for the two satellite columns in the table are based on actual, commercial experiences of international and domestic owners and operators. TABLE 3–1 Communications Relay Cost Summaries (Millions of Dollars Except Where Noted) Item

Terrestrial HF

International Satellite

Domestic Satellite

Initial cost per relay site or satellite plus launch vehicle

100–150

105

95

Initial cost per satellite control station

---

21

10

Annual operation and maintenance per site or satellite

8

2

2

20

7a 20b

10a 20b

Equipment lifetime (years) Total equivalent annualized cost

13–15.5

18

12

Total equivalent annualized cost for global coverage

130–155c

72d

48d

aSpace segment bGround segment cTen stations dFour satellites

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This gross comparison illustrates that the annualized cost of one terrestrial, HF relay station is approximately equal to that of one satellite, taking into account their respective equipment lifetimes of 20 and 10 years. It is, of course, significant that a typical VOA relay site can transmit only on the order of five to eight signals simultaneously, all with the geographical and time-dependent coverage limitations discussed above. By contrast, a satellite can transmit hundreds of audio signals simultaneously, depending on its design, with no time constraints and potential coverage of 90 to 120 degrees of longitude and ±70 degrees of latitude. Thus for total VOA coverage comparisons, there would be a large, per-channel cost difference in favor of four geostationary satellites over a total of 10 to 15 terrestrial HF sites. Also, the useful lifetimes of in-orbit satellites continue to grow. IMPACT OF LARGE SPACE PLATFORM TECHNOLOGY Studies over the past several years have addressed the future implications of large space platforms, both in geostationary orbit (Edelson et al., 1987; Barberis and Brown, 1986) and with the planned Space Station in low orbit (Vinopal and Willenberg, 1984). Because of its brief time in view, from any location on the Earth’s surface, the Space Station is considered as either an experimental facility or a staging base for in-orbit assembly of large space structures rather than an operational platform itself for large-antenna, high-power, communications systems. The potential availability of such large-antenna, high-power platforms was the impetus for some of the HF systems described in the National Aeronautics and Space Administration (NASA) studies for VOA (Bachtell et al., 1985; Horstein, 1985). As emphasized by Rogers (1985, 1987) and the National Research Council (1986) the time scale for developing and demonstrating the technology for very large geostationary satellites is greater than 10 years. Neither antennas in the range of 100 m diameter nor power systems in the range of hundreds of kilowatts are likely to be available in space for the next several decades within the current and planned programs for large space station development and deployment. The recent schedule stretchout for the Space Station deployment following the loss of the Challenger probably will delay their availability further. The above considerations argue strongly that large geostationary platform technology will not affect DBS-A in the near term. For their own agency interests, the Directors of the VOA and USIA should inform the Administrator of the National Aeronautics and Space Administration that it would be in the interests of the VOA and USIA (and, presumably, in the interests of the United States space and communications industries) if NASA were to proceed with the development of fundamental space technology needed to engineer effective and economical DBS-A systems. Meanwhile, present communications satellites could be employed initially, with special earth receivers used to allow local rebroadcast of the received signals. Then, perhaps, the technologies now being applied to DBS-TV could be adapted for DBS-A, with initial introduction by means

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of add-on payloads as described in the later section, Augmentation of Terrestrial High Frequency. Finally, a true, large-capacity, DBS-A system and service could be introduced. WORLDWIDE USE Before speculating on the future applications of DBS-A by third-world nations, it is well to note that two satellites owned and operated by two third-world countries for the purpose of direct satellite broadcasting, both television and audio, are already in geostationary orbit. The multimission INSAT located at 95.3 degrees East longitude contains payloads for fixed-service communications at 4 and 6 GHz, broadcast service at 2.5 to 2.69 GHz, and meteorological remote sensing. Two Arabsats, located at 19 and 26 degrees east longitude, serving the seven nations of the Arabian Satellite Organization, are also multimission satellites with twelve fixed-satellite channels at C-band (4 and 6 GHz) and two DBS channels at 2.5 GHz. Those satellites are still young in their respective lifetimes, so the extent of DBS service and the number of receivers are constrained by their current experimental nature. As the technology, service, quality, and receiver affordability are demonstrated over the next several years, DBS-A will become attractive to other third-world countries that can neither afford their own satellites nor have the abundance of terrestrial broadcasting services available in the West and in Japan. Broadcast satellites are being vigorously developed by Japan, Europe and Australia, primarily for television. The feasibility and desirability of incorporating DBS-A into these television broadcast satellites are recognized, and plans are in place to utilize them accordingly (Miller, 1987; Treytl, 1987; Johnson, 1987). By contrast, the United States has no current DBS program commitment to such an international activity in broadcasting satellite development, deployment, and use. The VOA, NASA, and the broadcast industry have not yet coordinated nor focused their efforts to apply available technology to provide DBS-A. While not strictly a satellite broadcasting service in the sense of direct user reception, radio programs are regularly distributed by satellite communications circuits in the United States, for example, by public radio, to affiliated amplitude modulation (AM) and FM stations. Equatorial Communications employs spread-spectrum techniques to broadcast Muzak service directly to franchised users with small-antenna terminals (2 to 3 feet at Cband, 4 GHz). AUGMENTATION OF TERRESTRIAL HIGH FREQUENCY The predecessor committee’s report (National Research Council, 1986) clearly recognized that replacement of the VOA’s HF, terrestrial, broadcast facilities with direct-broadcast satellites transmitting at HF is neither technically nor economically feasible for the very near future. However, the state of the art of satellite technology does offer several options for introductory use of satellite transmitters by the VOA and others for limited broadcasting or auxiliary functions. In each case,

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the following excerpts from the cited report recommend the early use of satellite transmitters to augment, not to replace, terrestrial HF: • “…DBS-A initially to supplement the present VOA worldwide system.” (page 4) • “…explore the possibility of providing low-capacity, direct audio broadcast satellite services at a relatively early time.” (page 12) • “…added to one or more private communication satellites to make VOA programming available at very low cost and with high quality and reliability.” (page 13) • “The VOA should plan for phased introduction of satellite services: • • • •

Near-term experimental phase Relay of VOA terrestrial transmissions Possible first-generation system based on current technology Possible second generation: higher capacity and worldwide” (page 58)

• “Satellite augmentation of terrestrial facilities: • Provision of additional services at S-band • Closed-loop monitoring of HF transmissions • Jamming avoidance” (pages 71–72) • “Local distribution of programming material” (page 72). All these current technology options for supplementing terrestrial HF broadcasting with DBS-A, whether by joint demonstration experiments (e.g., with INSAT, as recommended in the predecessor committee’s report) or by add-on payloads, would employ frequencies authorized for satellite broadcasting in the UHF or super-high frequency (SHF) bands rather than at HF, for the reasons discussed in the earlier section, Effectiveness of High Frequency vs Direct Broadcast Satellite. Although receivers for these bands are not now available in quantity or at reasonable cost, the survey cited in the earlier section, Receiver Availability, showed that this lack is not due to technical factors but to lack of demand. Demand will motivate manufacturers readily when signals are available for reception. As noted in the survey, the manufacturers’ response time is measured in months, not years, and this is considerably shorter than the several years’ development and deployment cycle of the satellite equipment. CONCLUSIONS The potential advantages to the VOA (and to all the other international, audio broadcasters throughout the world) of DBS-A in terms of reliability, service-area coverage, signal quality, reduction of installation and operating costs, channel capacity, and reduction of the likelihood of jamming are compelling. Over a year has passed since the findings and recommendations of our predecessor committee urged the VOA to establish within its organization a group responsible for formulating and

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implementing a plan to introduce satellite broadcasting into its operations. Four elements of such a plan were defined for this new element of the VOA organization (National Research Council, 1986): • Long-range planning and development program • Study of 2.5 to 2.69 GHz DBS-A • Phased introduction of a worldwide, direct-satellite-broadcasting service (near-term experiments and demonstrations, satellite relay of terrestrial programming, first and second generation systems and service, and receiver development at appropriate frequencies) • Political, financial, and regulatory matters fundamental to worldwide acceptance of DBS-A. Indeed, the report states (at p. 11), “Direct audio broadcasting by satellite…could be available by the year 2000,” and “An institutional arrangement should be considered…for the possible provision of a common-carrier, common-user service.” As yet, there is no formal, organizational focus within the USIA or VOA to address DBSA. These recommendations are still valid. The Committee reiterates them as all the more urgent as they have to be incorporated into the VOA’s activities in time to allow the United States to be prepared satisfactorily for the 1988 World Administrative Radio Conference. RECOMMENDATIONS The VOA should now begin to position itself to enter the age in which satellites are used to supplement terrestrial, short-wave transmitters so as to improve direct-to-the-listener broadcasting of its programs. Technologically, the way is now clear for orbiting transmitters to broadcast audio programs directly to home receivers over nearly the entire globe (and in particular to all 15 of the VOA service areas), to do so with the excellent quality and reliability offered by satellite communications circuits today in the provision of radio and television distribution services and to do so at a lower unit cost than that of surface-based HF. The following four recommendations constitute the major milestones in a roadmap for the VOA’s introduction of satellite direct audio broadcasting. The Director of the VOA should take the following actions: 1. Assign a senior professional with ready access to the Director (perhaps in a new position of Chief Scientist) the responsibility and staff (of not more than two or three people) to develop the details of a phased plan for: a. Demonstrations with existing satellites b. Subsequent provision of early, modest, DBS-A capability via add-on payloads to host satellites c. The definition of a dedicated, high-capacity, common-carrier, world-wide, satellite DBS-A system. 2. Allocate a modest sum, say $500,000 annually, for this designated professional to engage the services of satellite technology and service experts to assist in defining such a multiyear VOA plan.

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3. Participate actively, with VOA in-house and contractor support personnel, in developing the U.S. delegation position in concert with the National Aeronautics and Space Administration and the Departments of Commerce and State for the forthcoming 1988 Space World Administrative Radio Conference concerning allocation of frequencies for direct satellite broadcasting of audio programming, and participate in the delegation’s activities at the Conference. 4. Engage in liaison with the receiver industry, both domestic and foreign, to define the characteristics and economics of a new generation of DBS-A receivers, enlisting industry participation in the initial demonstrations noted above. 5. The Directors of the VOA and USIA should inform the Administrator of the National Aeronautics and Space Administration that it would be in the interests of the VOA and USIA (and, presumably, in the interests of the United States space and communications industries) if NASA were to proceed with the development of fundamental space technology needed to engineer effective and economical DBS-A systems. In addition to these recommendations for USIA or VOA action, the concept of DBS-A is now sufficiently mature technically, financially, politically, and operationally for the Committee to recommend that VOA inform both the White House and the Congress of the opportunities that it presents. REFERENCES Bachtell, E.E., S.S.Bettadapur, J.U.Coyner, and C.E.Farrel. 1985. Satellite Voice Broadcast System Study. Final report by Martin Marietta Corporation to the NASA Lewis Research Center. NASA-CR-175017. Cleveland: National Aeronautics and Space Administration. Barberis, N.J. and J.V.Brown. 1986. Design Summary of a Geostationary Utilized as a Communications Platform. Paper presented at American Institute of Aeronautics and Astronuatics (AIAA) 11th Communication Satellite Systems Conference, March 17, 1986. AIAA Paper No. 86–0714. Edelson, B.I., R.R.Lovell, and C.L.Cuccia. 1987. The evolution of the geostationary platform concept. IEEE Journal on Selected Areas in Communications. Vol. SAC-5, No. 4, May. Fortner, Robert S., et al. 1986. A Worldwide Radio Receiver Population Analysis. Washington: The Academy for Educational Development. May. Horstein, M.1985. Satellite Voice Broadcast System Study. Final report by TRW, Incorporated to the NASA Lewis Research Center. NASACR-174905. Cleveland: National Aeronautics and Space Administration.

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Johnson, C.1987. DBS Systems Including Sound Broadcasting. Paper presented at the 15th International Television Symposium, Montreux, Switzerland . June 12, 1987. Miller, J.E.1987. Technical Possibilities of DBS Radio at Near 1 GHz. Paper presented at the 15th International Television Symposium, Montreux, Switzerland. June 12, 1987. National Research Council. 1986. Modern Audio Broadcasting Facilities for the Voice of America. Washington: National Academy Press. Rogers, T.F.1985. Spaced-Based Broadcasting: The Future of Worldwide Audio Broadcasting. Washington: National Academy Press. Rogers, T.F.1987. Worldwide direct audio broadcasting from space— promoting “glasnost” with DBA-A. Space Policy 3(August):232–238. Treytl, P.1987. Demonstrations of 16-Channel Sound Broadcasting by DBS. Paper presented at the 15th International Television Symposium, Montreux, Switzerland. June 12, 1987. Vinopal, T. and H.Willenberg. 1984. Space Station Impact on Communication Satellite Systems. Paper presented at American Institute of Aeronautics and Astronautics (AIAA) 10th Communications Satellite Systems Conference, March 21. AIAA Paper No. 84–0705.

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4 EMERGENCY PREPAREDNESS TELECOMMUNICATIONS This chapter surveys several aspects of emergency preparedness that affect Voice of America (VOA) planning and operations. The first two sections point out the importance of mission definition for an emergency and the interacting roles of VOA and emergency preparedness efforts of other government agencies. Once these functions are clearly prescribed, priorities and requirements for emergency preparedness can be addressed. The chapter finds that current emergency planning should be strengthened, particularly by attention to a systems approach and increased awareness of National Security Emergency Preparedness (NSEP) planning. Finally, the chapter recommends ten measures that should enhance the VOA’s ability to discharge its responsibilities in crisis. MISSIONS The VOA’s mission is to broadcast truthful, accurate information regarding the U.S. government’s policies and American cultural values to countries throughout the world. These broadcasts are currently transmitted in forty-two languages and represent a principal source of information about the United States to the indigenous populations of these countries. The VOA organization has extensive resources, including broadcast facilities and staff, and the operating policies and procedures necessary to conduct its day-to-day broadcast operations. Although the present VOA resources operate well under normal conditions, they may not do so under emergency conditions. The VOA’s mission becomes even more critical during emergency situations. Therefore, emergency preparedness plans must be formulated to position essential operational resources, to ensure availability of critical communications, and to guide operations during emergency conditions. The Committee reviewed the VOA’s emergency preparedness plans and the status of its emergency preparedness telecommunications. The Committee concluded that the VOA’s current emergency preparedness plans suffer from two flaws: (1) lack of a clear definition of what constitutes an emergency and (2) lack of a clearly defined mission to pursue in the event of an emergency. The current plans as written address rather trivial events which do not meet the most basic definition of an emergency: a sudden,

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urgent occurrence requiring immediate action. This may be the result of the failure of appropriate officers of the government to provide a reasonable mission for VOA to pursue in the event of a defined emergency. The extant mission statement for emergencies --to continue broadcasting in the official United Nations languages -- is so vague that it fails to provide the guidance necessary to distinguish an emergency from, say, a failure of the plumbing system. Planning VOA emergency preparedness procedures is difficult, then, since the VOA lacks tangible mission objectives for emergency situations. The result of this failure is that the VOA's current emergency preparedness plans are wholly inadequate. They have not yet progressed beyond consideration of trivial events that may affect the ability of the VOA Washington staff to continue operations at current levels. Although the logic of the current effort is understandable --to begin at the most basic levels of emergency and work up to the most complex -- the starting point established was so localized that it seems to confuse inconvenience with real necessity for action. This is demonstrated by the number of occasions in the plans in which the defined "emergency" requires no adjustment of current operations. In fact, these occasions would not be emergencies. Emergency preparedness should be approached from the perspective of the VOA's fundamental mission in the event of an emergency. This requires both that the mission be made explicit and that the emergencies of concern be defined. A number of potential emergency missions are implied for the VOA by National Security Decision Directive Number 47 (NSDD-47), National Security Decision Directive Number 97 (NSDD-97), and Executive Order 11490. The current starting point—to continue broadcasting in the official United Nations languages—should be expanded to indicate (a) to what regions each language should be broadcast; (b) at what specific intervals (in hours or minutes) authority to determine broadcast content in these languages would cascade down the levels of responsibility to the individual relay stations; (c) what priorities of content exist for broadcast in each language; and (d) what the sources of content are to be in each language, particularly in news broadcasts, which cannot be prepared in advance. Directives for response to these issues should serve as the starting point in determining the VOA's required response to emergencies and thus the necessary technical personnel, facilities, and operations procedures to carry out emergency preparedness and, eventually, emergency operations. In particular, such directives would provide the necessary guidance to plan reliable, redundant, and reconstructable communications links among the facilities housing the personnel and equipment to carry out an emergency mission. Relying on the current, overly broad mission statement fails to consider key issues which will have great significance during periods when resources are strained and priorities uncertain. The expanded mission statement must also be consistent with NSEP requirements and indicate where appropriate interfaces with NSEP procedures are appropriate.

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The VOA’s need for dissemination of critical broadcast information should be integrated into the NSEP process to assure planning for VOA communications connectivity. Information dissemination and facility requirements must be coordinated through the national NSEP program to ensure compatibility with facilities, national objectives, and priorities. ROLES, RESPONSIBILITIES, AND REQUIREMENTS At present, the VOA depends on other government agencies and organizations for emergency planning. Through NSDD-97 and Executive Order 12472, which define national security telecommunications policy and establish authorities and operating conditions, the United States Information Agency (USIA) was designated as one of the 22 member agencies of the Committee of Principals in the National Communications System. The Office of the Manager, National Communications System (OMNCS), is responsible for establishing NSEP telecommunications to support critical leadership functions of the federal government in times of emergency or national crisis. The Committee has learned from the OMNCS that the USIA has not addressed its NSEP responsibilities to participate in planning meetings, to identify appropriate emergency responses, and to ensure USIA and VOA participation in national emergency preparedness activities. So, while the VOA believes it should have an NSEP mission, a need to ensure continuity of operation, and a requirement for ensured communications connectivity in a national emergency, there is no evidence that current plans truly address an NSEP emergency. Effective NSEP planning requires, however, that the VOA have a mission as well-defined for emergencies as it does for its day-to-day operating mission. Only when the VOA has a well-defined NSEP mission and participates directly in emergency preparedness planning will it be able to plan for and exercise NSEP communications to support its national emergency obligations. In the Committee’s view, since the VOA has not received the support it perceives it needs from the USIA, the VOA should not continue to depend on the USIA for NSEP guidance. Rather, it should seek the agency representation authority and participate directly in NSEP planning. To support this action the VOA should prepare correspondence for the Director, USIA, nominating and designating a VOA principal as the representative to the Committee of Principals. The VOA’s emergency preparedness needs may be unique compared with those of other members of the Committee of Principals. For instance, one principal feature of the planning environment for emergency preparedness, articulated by the final report of the National Research Council’s Committee on National Security Telecommunications Policy Planning Environment (National Research Council, 1986), is that predesignated government executives may not be where they are needed in the aftermath of an emergency. Because of that, that committee recommended that all recovery and reconstitution efforts be planned and organized to start at bottom organization levels. But, given the VOA’s

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international role, it is imperative that quick response to reconstitute viable linkages among news sources, editorial offices, studio facilities, and broadcast relay sites be planned, organized, and exercised to include participation by all levels of the VOA structure. It is difficult for foreign relay stations to broadcast without central direction, and they may be outside the emergency zone itself. Accordingly, personnel at these sites must have direction in advance of an emergency that would allow them to continue operations. Simple, standard operating procedures posted in prominent positions at each installation for use in emergencies would help onsite personnel in such circumstances. While continuing, they should also seek central direction over pre-established emergency links utilizing the full range of technological capabilities, including satellite, undersea cable, and high-frequency (HF) (including amateur) links, as well as alternate service monitoring of such broadcasters as the British Broadcasting Corporation (BBC) and the Armed Forces Radio & Television Services (AFRTS). The VOA should make reciprocal arrangements with such organizations to attempt emergency links on preselected frequencies or to use their wired satellite links as necessary to re-establish service as quickly as possible. The VOA’s emergency preparedness requirements for facilities, personnel, and logistics arise directly from its mission requirements and objectives under Executive Order 11490. During a national disaster, the VOA must be able to continue to broadcast in the six United Nations languages (namely, English, French, Russian, Chinese, Spanish, and Arabic) from both domestic and foreign relay stations and to transmit wireless files to U.S. missions abroad. To do this, the VOA must have continued access to National Command Authority messages, capabilities to develop programming material, technical means to communicate messages to broadcast and relay sites, and technical means to broadcast the messages to target audiences. DISASTERS AND PRIORITIES Significant Problems in Disasters Local and regional disasters might strain communications and logistics within the impacted areas and present a challenge to the VOA’s ability to cope with their effects, but national disasters constitute the most critical emergencies, presenting severe problems related to massive and widespread destruction to which the VOA must respond. In all cases the most critical problems facing the VOA are (1) to reconstruct the vital studio-totransmitter links (STLs) to ensure continuity of broadcast operations and clear direction to remote relay stations regarding their roles in emergency responses and (2) to provide content for broadcast that will reassure world audiences of appropriate U.S. response to the emergency situation and continuity of government operations. The more severe and widespread the emergency situation, the more crucial the rapid reconstruction and programming activities are. The worst kind of

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national disaster would be a nuclear attack or exchange, in which a significant portion of the United States’ national communications and governmental operations could be disabled or destroyed. It is for such cases that the VOA must have a well-articulated mission and the emergency preparedness planning required to ensure that that mission can be implemented successfully. A nuclear exchange most likely will be preceded by a heightened period of tensions. The VOA’s mission during this period could become critically important to ensure that the U.S. message is received and understood throughout the world by both allies and adversaries. During and after the hostilities, the VOA must have the means to perform its mission to assure the world that U.S. governmental functions are continuing, thus providing public reassurance and preventing interdiction by third parties. A national disaster will strain all traditional communication and logistics resources severely, and it will present the VOA with a situation in which restoration will be particularly complex. A national disaster planning process with resources limited to those the VOA has currently in place cannot ensure continuity of operations. The VOA’s challenge is to search for innovative, cost-effective approaches to maximize the chances of mission success in the most difficult of situations. Dependence on “bottom-up” reconstitution and low-technology solutions will facilitate efforts to reconstitute studio-to-transmitter links (STLs) when main installations are damaged. Dependence on local authorities and radio facilities to reestablish broadcasting capability is more likely to allow a quick return to the air than would elaborate national plans dependent on reconstructing VOA’s main facilities (p. 10 in National Research Council, 1986). Mission Priorities While the VOA’s overall mission during disasters is to continue uninterrupted operations, limited resources dictate that certain priorities must be established. In preparing for a national disaster, the starting point should be the planning for critical backup communications for studio facilities and STLs to the highest-priority broadcast and relay facilities. In addition, chosen audience areas should be prioritized to use available resources most effectively. Language specialists, newswriters, and other specialists unique to the VOA mission should be identified, to be drawn on if a national emergency occurs. While the priority designation process should be predetermined, it may become necessary to carry it out in near-real time. This suggests the need for competent, well trained people in the field, where the reconstitution of mission capability can be effectively initiated. And, as stated earlier, it is here that clear directives for field operations and efforts to reestablish central direction from both field sites and central control are essential. Field operations directives

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must state simply and clearly the authority that may be assumed and the operating procedures to be followed, including those for restoring relay communications until STLs have been reconstituted. The VOA should also establish a system similar to that of the National Defense Executive Reserve, using personnel in diverse geographic areas where backup studio facilities are located who can provide programming for continuing VOA relay-site operations. THE VOICE OF AMERICA’S EMERGENCY PREPAREDNESS REQUIREMENTS The VOA’s emergency preparedness requirements for facilities, personnel, and logistics arise directly from modification of its mission during disasters. During a national disaster, the VOA must have the following capabilities: • • • •

Continued access to the National Command Authority’s message Ability to develop programming material Technical means to communicate messages to broadcast and relay sites Technical means to broadcast the messages to target audiences.

The VOA must ensure that it has the physical plant, communications links, trained personnel, and logistics to achieve these objectives. From this perspective, the Committee finds several attributes that the VOA system requires for NSEP: survivability, endurability, flexibility, ingenuity, and the ability to restore and reconstitute the system. Survivability To fulfill its mission during a national disaster, the VOA must ensure the survivability of its personnel, facilities, and communications links. Technical means to accomplish survivability range from “hardening” to protect against nuclear effects, including electromagnetic pulse, to creating backups. Good engineering practice for lightning protection may suffice to harden sites against electromagnetic radiation from atmospheric nuclear bursts. But the VOA should consider at least some minimum measures to protect against effects of high-altitude electromagnetic pulse (HEMP) on ground systems. Low-level, control, and signal circuits are likely to be vulnerable. The VOA should also consider some measures to protect against effects of high-altitude nuclear detonation on ionospheric propagation. However, the extent of protection depends on the nature of the requirements for mission performance and operational continuity. Such requirements have not been set forth by VOA in a form definite enough to allow decisions on the priorities and extent of HEMP protection. For example, the duration of allowable service outages during and after a nuclear attack and the extent of necessary

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geographical coverage all affect decisions on the nature of backup power provision and radio frequency circuit protection. The Committee on National Security Telecommunications stated in its annual report (National Research Council, 1985) that “adequate attention to lightning protection is quite likely to suffice in many cases for EMP [electromagnetic pulse] protection as well. For example, sensitive semiconductor devices must be isolated from the electromagnetic radiation pickup of long cables. This is well-known radio-wavelength radiation practice for lightning protection…CMOS [complementary metal oxide semiconductors], NMOS [n-type metal oxide semiconductors], and bipolar devices are not significantly different in basic vulnerability to radio-frequency radiation, while GaAs ICs [gallium arsenide integrated circuits] are likely to be slightly more vulnerable. Single, opto-electronic devices such as lasers and detectors are far less vulnerable because of their inherent design for high bias values: high, forward-biased current in lasers and high, reverse-bias voltage in the detectors. Conventional, vacuum, electronic devices are inherently rugged, and even the micro-integrated versions are likely to retain this capability.” (pp. 24–25)

Thus, the Committee concludes that good engineering practice for lightning protection, supplemented by protection against radiation pulses coming in on the power lines by zener diodes or gas-discharge tubes, will provide adequate survivability against HEMP. In addition to the coupling of HEMP through power lines, direct radiative coupling of HEMP also occurs, with possible destruction of semiconductor devices in VOA circuits. However, this is a less severe threat than in military electronic equipment because of the different nature of the circuits. Nevertheless, the threat should be considered and military penetration protection device technology should be fitted if warranted. Finally, the waveform and spectrum of HEMP differ from those of lightning in having faster rise times and consequently higher frequency components. Accordingly, if extensive digital multiplexing were to become a part of the VOA design, such circuits would be vulnerable to the HEMP “upset” phenomenon. Under “upset” the circuits components are not destroyed, but their logical and numerical operation is temporarily compromised until they can be reset to initial conditions. Power to operate relay and broadcast facilities, however, presents another survivability problem. Here, the Committee on National Security Telecommunications (p. 9 in National Research Council, 1985) concluded that “…power will be largely unavailable in the more highly stressed situations.” The VOA should prepare for this eventuality by providing its alternate sites with standby power generating facilities and the fuel to run them for extended periods. Protected power has been engineered as part of such military communications systems as the Ground Wave Emergency Network (GWEN). VOA might find GWEN backup power technology and design helpful in case of commercial power failure.

Antennas, Satellite Broadcasting, and Emergency Preparedness for the Voice of America, National Academies Press, 1999. ProQuest Ebook Central,

Copyright © 1999. National Academies Press. All rights reserved.

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Changes in the ionosphere following a nuclear detonation could cause disruptions preventing transmission of HF signals for extended periods of time, as long as 24 hours. Even at very-high frequency (VHF), satellite links will have outages under such conditions lasting from 30 minutes to a few hours, depending on frequency, with lower frequencies being affected for longer times than higher frequencies. At ultra-high frequency (UHF), ionospheric disturbances induced by nuclear blasts may impair transmission for days. At super-high frequency (SHF), impairment may last for a couple of hours. At extremely-high frequency (EHF), scintillation is not a major problem. Thus the VOA should maintain and use a flexible mix of communications means and interfaces, at different frequencies, to assure continued operation in the event that any single means of communications is interrupted by a range of possible disruptions due to physical or EMP disturbances. Multiple detonations may cause longer-lasting effects over greater geographical areas. The VOA’s options for coping with contingencies caused by ionospheric disturbances may be limited to broadcasting from the alternate transmitter site(s) outside the affected region. The VOA should consider alternative means of disseminating the broadcast message to these transmitter sites. The alternative means could be satellites and low-cost receive-only terminals at alternate transmitter sites. However, alternative transmitter sites will not help if the audience area is affected. Technologies such as direct audio broadcasting by satellite (DBS-A) could help solve this problem. DBS-A systems will operate at microwave frequencies and thus have greater immunity to the effects of atmospheric scintillation. In addition, the portion of the satellite signal propagation path through the atmosphere will be much smaller than that for terrestrial, HF transmissions. Even so, appreciable immunity will require appropriate processing of the satellite signals at both ends of the path. However, the regulatory, fiscal, and technical hurdles facing DBS-A make it unlikely that this solution can be available within the next decade. Geographic dispersion of facilities is a traditional engineering approach to promote the survivability of technical systems. This approach would work particularly well during local and regional disasters. It also may work during a national disaster if sufficient redundancy is provided. For STLs, that could be done through planned redundancy of commercial services, both terrestrial and satellite. The VOA should not assume it necessary to construct its own backup facilities, since this approach has disadvantages—primarily the high costs of building and maintaining the backups. System planners for VOA should consider the possibility of co-siting some VOA sites with GWEN sites. Land is already available, the sites are dispersed, and VOA personnel would not be as vulnerable as in Washington, D.C. Co-siting studios and studio-transmitter links with university and commercial broadcast sites are also good ideas. In addition, many hospitals have usable emergency power. The VOA should attempt to ensure survivability

Antennas, Satellite Broadcasting, and Emergency Preparedness for the Voice of America, National Academies Press, 1999. ProQuest Ebook Central,

Copyright © 1999. National Academies Press. All rights reserved.

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through innovative approaches to redundancy, such as use of mobile facilities and possibly commercial broadcast facilities and colocation of VOA-unique systems at existing commercial or public communications and broadcasting stations. For example, a mobile, news-gathering van could serve multiple purposes as a satellite relay station from or to emergency locations such as command centers, temporary studios, relay sites, or broadcasting sites. At the first warning of hostilities, the mobile facilities could be directed to proceed to their preassigned locations or to any other locations that might be dictated by the particular situation. In addition, the mobile, newsgathering unit could be used on a day-to-day basis to extend the quality and accuracy of news reporting by having live, on-scene coverage. Every major city in the United States has a number of commercial broadcast studios to serve the local markets. VOA’s needs for studios during emergencies could be met by commercial studios and broadcast facilities that could also serve as communications relay facilities to the VOA broadcasting sites. The Committee believes that the cost of connecting these studios to the broadcasting sites may be much less than the life-cycle cost of developing VOA’s own alternate studio and broadcasting sites. Interconnection could be either AM or FM, with rebroadcast at HF from the broadcasting sites. Commercial satellite terminals could also be used to provide critical, redundant, communications paths between studio facilities and broadcasting sites. Another attractive aspect of ensuring survivability through geographical dispersion lies in locating VOAunique systems on, or adjacent to, existing commercial or public communications terminals. These terminals are connected to the outside world through a variety of systems such as microwave, fiber-optic cable, and satellites. At the same time, they are technically equipped to service the VOA functions. VOA-unique equipment may have to be added, such as small, HF, relay antennas and transmitters or satellite earth-station transmitters and receivers, but the cost of these additions would be much less than that of developing a complete, new, facility complex. Such facilities are referred to as cooperative facilities. Endurability Endurability is the ability to continue to operate for a specified period when equipment and facilities fail sporadically. The length of time that a system may continue to operate is based on the degree of system redundancy and the availability of necessities such as food and fuel. The VOA’s communications system should be prepared to endure for up to several months before resupplying. This requirement will dictate the number of spares and the amounts of consumables and supplies that will be required. In a general nuclear war scenario it is unlikely that any of our major U.S. transmitter sites will endure without their own standby, emergency-power generation, since they depend on the national power grid, which is expected to be down. Lacking adequate standby power-generating capability at U.S. transmitter sites, the VOA’s operational endurability will depend on U.S. communications links to overseas transmitter sites.

Antennas, Satellite Broadcasting, and Emergency Preparedness for the Voice of America, National Academies Press, 1999. ProQuest Ebook Central,

Copyright © 1999. National Academies Press. All rights reserved.

About this PDF file: This new digital representation of the original work has been recomposed from XML files created from the original paper book, not from the original typesetting files. Page breaks are true to the original; line lengths, word breaks, heading styles, and other typesetting-specific formatting, however, cannot be retained, and some typographic errors may have been accidentally inserted. Please use the print version of this publication as the authoritative version for attribution.

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Flexibility Flexibility is the ability to use a variety of communications means and interfaces to respond promptly to emergency needs. It also implies the ability to use surviving facilities, whether fixed, mobile, or appropriated under emergency powers, to perform the mission under adverse circumstances. Planning for emergency communications will be critically important in establishing a capability to interconnect surviving VOA facilities. Flexibility and survivability are closely related. For example, a system with fixed primary and fixed backup facilities lacks flexibility compared to a system comprising both fixed and mobile facilities. Neither is the system with fixed primary and fixed backup as survivable as the system with both fixed and mobile facilities. The VOA should avoid the simplistic approach of relying solely on fixed, VOA-owned facilities. Ingenuity Ingenuity is difficult to translate into specific technical requirements. However, ingenuity implies system resiliency and is most evident in the technical level and proficiency of the work force. VOA should pay special attention to training and exercising its staff as part of its preparation for emergency situations. It should also understand that effective reconstitution of technical facilities usually is more effective when the whole organization approaches it from a “bottom-up,” as well as “top-down,” perspective. In that regard the development of effective and simple standard operating procedures that grass-roots personnel can use will call for a high level of ingenuity from the planners. Restoration and Reconstitution of Communications and Mission Capability Operational capability and communications interconnectivity cannot be easily reconstituted from a top-down approach. Top-down reconstitution is generally unworkable. Generally the top echelon has the least likelihood of survival, particularly if it is situated in the Washington, D.C. area. Also, the majority of the mission objectives can be carried out by the lower-echelon organizations provided well thought-out emergency plans and procedures are in place. Dispersed, lower-echelon, operating units are more likely to survive, and local leadership will emerge. With adequate emergency planning and well trained and well equipped operating personnel, the lowest-level, operational units can reconstitute operational capability rapidly. Consequently,

Antennas, Satellite Broadcasting, and Emergency Preparedness for the Voice of America, National Academies Press, 1999. ProQuest Ebook Central,

Copyright © 1999. National Academies Press. All rights reserved.

About this PDF file: This new digital representation of the original work has been recomposed from XML files created from the original paper book, not from the original typesetting files. Page breaks are true to the original; line lengths, word breaks, heading styles, and other typesetting-specific formatting, however, cannot be retained, and some typographic errors may have been accidentally inserted. Please use the print version of this publication as the authoritative version for attribution.

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plans and procedures should be developed for bottom-up reconstitution of operational VOA capabilities in the event of a national disaster. Furthermore, periodic exercising of plans and procedures will provide insight into their strengths and weaknesses and help identify additional capabilities and resources required for emergency preparedness. Such bottom-up reconstitution will require pre-positioning of programming material and critical logistic support items at backup studios, relay sites, and broadcast facilities. As operational control is restored, the VOA can envision the escalation of command or management authority until a full, top-down, communications capability is re-established. THE VOICE OF AMERICA’S CURRENT EMERGENCY PREPAREDNESS PLANS The VOA’s current emergency preparedness plans are designed to cope only with limited contingencies for facilities and people rather than with the VOA’s ability to perform its mission under conditions of national disaster. These plans do not address the important aspects of emergency preparedness. They have been created in a vacuum, in the absence of direction from the USIA or participation by that parent agency in NSEP telecommunications planning. Moreover, the current plans are deficient in their failure to address staffing and organizational requirements. The plans seem to assume that all the VOA people somehow will appear magically at the VOA’s backup facilities, that all communications will be available with no facilities impaired, and that day-to-day operations will be resumed easily once everyone is in place. Much more attention must be devoted to the people, communications facilities, electric power, organizational structure, operating procedures, and logistics to define how the facilities will be manned and operated. This approach will lead to the development of more acceptable emergency planning. Specifically, the Committee recommends the following steps: • Drafting a mission statement for the various levels of VOA facilities, including headquarters, backup news production and studio sites, and relay stations. The mission statement should assign specific responsibilities to each level, including operating authority and simple, standard, operating procedures to be followed in seeking both system reconstitution and alternative program content. • Consultation with telecommunications network designers to determine reasonable technical means to reconstitute STLs in the event of a national emergency • Consultation with private-sector news-gathering, broadcasting, and telecommunications service providers to establish procedures for emergency use of equipment such as mobile, news-gathering vans, alternative studios, and satellite transponders • Establishing an emergency preparedness office at each VOA backup site and relay station, and providing the authority to this office to locate sources of necessary fuel, food, supplies, and transportation for short-term operations.

Antennas, Satellite Broadcasting, and Emergency Preparedness for the Voice of America, National Academies Press, 1999. ProQuest Ebook Central,

Copyright © 1999. National Academies Press. All rights reserved.

About this PDF file: This new digital representation of the original work has been recomposed from XML files created from the original paper book, not from the original typesetting files. Page breaks are true to the original; line lengths, word breaks, heading styles, and other typesetting-specific formatting, however, cannot be retained, and some typographic errors may have been accidentally inserted. Please use the print version of this publication as the authoritative version for attribution.

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SYSTEMS APPROACH TO EMERGENCY PLANNING Planning Fundamentals Planning emergency preparedness is difficult for the VOA since it lacks a tangible mission objective during a national emergency. The requirement of simply being able to “broadcast in six primary languages” fails to take into consideration key issues which may have greater significance when resources are limited and priorities must be established. A definitive emergency mission statement should include a vision of how the VOA contributes to our national objectives and fulfills an NSEP requirement. The statement should also include why, what, when, and where messages should be broadcast and in what languages. Without a rationale consistent with NSEP it will be difficult to get support or funding for a viable VOA emergency preparedness program. Emergencies that require immediate action must be defined. These emergencies should include sudden, urgent events affecting the abilities of the Washington staff to deliver program content to relay sites and of the relay stations to deliver program content to audiences. Thus, both domestic and international emergencies must be addressed. Any events that do not affect one of these two abilities should not be included in emergency preparedness plans, but may be included in standard operating procedures governing day-to-day activities in the VOA. In this, it is essential that the VOA staff distinguish clearly between real emergency situations and localized, daily inadvertencies such as temporary loss of plumbing or air conditioning. The emergency plans outlined should be clear, direct, and simple. Although such plans should be complete, their effectiveness will be positively related to their brevity. Overly complex plans, excessive contingencies, and attention to trivia will compromise the effectiveness of the plans in two ways. First, efforts to become familiar with the plans prior to an emergency will be frustrated, thus resulting in minimal understanding by important personnel. Second, efforts to use the plans in the event of an emergency will be frustrated, thus resulting in personnel having to improvise responses during the emergency, with the inevitable loss of coordinated activity across the system. Because the emergency plans fail to define genuine emergencies or to address the emergency planning adequately, the Committee was not surprised to find that the VOA’s current emergency staffing plans had not considered the hurdles, such as the lack of transportation-facilities, that may impact manning and provisioning of the backup facilities. One possible solution to the need to relocate VOA expert staff from the Washington, D.C. area to the backup sites during emergencies might be to transfer some of the technical functions to the backup sites permanently.

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Responsibility for developing and implementing emergency preparedness plans should rest with a single authority, composed of a single office of two or three individuals in a clear chain of command. If there is to be an emergency preparedness office, that office should also be prepared and authorized to respond to an emergency by taking charge when it occurs and ensuring that the emergency mission of the VOA is executed. The personnel in the emergency preparedness office should be those most familiar with the plans for emergency response, and should take charge until the emergency situation stabilizes sufficiently to allow normal operational channels to function. In the Committee’s view, the head of that office should also be a member of the Committee of Principals of the National Communications System. Dispersed and Cooperative Facilities The weakest link in the VOA system is the vulnerability of the single most important element—the VOA infrastructure, in Washington, D.C., for generating and disseminating programming material. Therefore, it is apparent that the single most important VOA emergency preparedness recommendation is to provide for some program origination and distribution capabilities outside the Washington, D.C. area. Although relocation of the Washington, D.C. facilities may not be feasible, it may be possible to create some sort of ready reserve capability at a few less vulnerable locations, perhaps in the vicinity of VOA domestic relay sites. Relocating critical VOA facilities at less vulnerable, less urban, geographic areas would increase the possibility of continuous operation in a national disaster. Today’s modern communications systems are virtually insensitive to distance between broadcast studios and broadcast sites. Since the location of studios is irrelevant to the VOA’s day-to-day operations, it is reasonable to disperse critical facilities to areas that offer minimum vulnerability and high availability of essential operational support resources such as interpreters, food, fuel, water, standby power generation, and communications facilities. Studio facilities and other support resources needed for daily operations should be colocated at those broadcast facilities. Colocation will not increase the vulnerability of broadcast facilities, and relocation to less vulnerable sites will increase the possibility of VOA’s overall, operational survivability. The Committee’s recommendation to colocate studios with the broadcast facilities does not mandate that the studio and transmitter sites be the same; only that they be located in the same geographic area. Because of the VOA’s unique requirements for interpreters, it may be desirable to locate the studio near a university with large, foreign-language departments. One efficient approach to relocation of critical VOA facilities might be to install the studio on a university campus, particularly if the university has a media communications department and a radio station.

Antennas, Satellite Broadcasting, and Emergency Preparedness for the Voice of America, National Academies Press, 1999. ProQuest Ebook Central,

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Cooperation between the VOA and universities with language and media communications programs could give rise to a low-cost approach to providing redundant studio facilities and interpreters. Universities are also located in areas that can provide needed support facilities such as food, fuel, housing, and manpower. Arrangements could be made with local schools, law-enforcement agencies, fuel-distribution centers, local power authorities, and local National Guard units to provide a full range of support services, resources, and supplies to meet the VOA’s emergency operational requirements. Program Content Alternative sources of news content should be considered and defined, including such emergency measures as monitoring other broadcasters, such as the BBC World Service or AFRTS, to allow continuation of newscasts when U.S. VOA or other domestic sources may not be available. Normal VOA HF facilities can be used, or satellite connectivity can be established between these alternative news sources and backup studio, relay, or broadcast facilities. Programming material for day-to-day operations can be transmitted from Washington or any other desired location by satellite. Under emergency conditions, programming material could be transmitted directly from any site, such as a relocation center, through a mobile, news-gathering, satellite earth station. The mobile satellite earth station could be located at the National Command Authority fallback site. The mobile station also could be used for both daily and emergency operations to provide on-site news-gathering communications directly to the VOA studio. Permanent relocation of VOA studios also would reduce the amount of preparation needed for emergency operations under disaster conditions. Such relocation would not only provide a low-cost solution to emergency preparedness, but could also reduce the cost of daily operations considerably. Pretaped, “canned,” programming material should be created and a system established to update it in nearreal time. This can be implemented in our interactive data-base system and can even be digitally encrypted for transmission security. Procedures for the devolution of operational management and control functions should contain conditions and procedures for the use of this canned material. System Connectivity The key element to preparing the VOA for emergencies is providing the redundant communications capability to ensure connectivity between critically needed VOA facilities and key personnel. The proliferation of satellite communications capability, both domestic and international, provides a viable and relatively low-cost means for establishing critical communications links. The Committee recommends that the VOA develop a communications master plan that would include

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small, satellite earth stations to be located at primary and backup VOA facilities. While each major facility should have a two-way, satellite communications capability, it is also desirable to have multiple, receive-only capabilities at many of the sites. Low-cost, satellite, receive-only capability could be established with extremely low-cost connectivity from several different satellite sources. For example, a single VOA station could have receive-only equipment monitoring several different satellites, such as two domestic and two international satellites. The smaller stations could be tuned to preset frequencies on single-carrier-per-channel transponders; or could even be tuned to frequencies on video transponders where audio transmissions can be carried on one of the video subcarriers. This could serve a twofold purpose: (1) to receive video news broadcasts on any of the affiliate newsgathering and relay transponders and (2) to include an emergency preparedness procedure that would allow VOA audio to be carried on one of the transponder subcarriers in the event of a national emergency. The receive-only, audio, earth stations can be installed and placed into operation for as little as $2,500 per installation, with only a small, monthly, recurring charge for operation and maintenance and periodic testing, unless there is an intent to use these stations for day-to-day operations. In any event, the Committee recommends that a satellite architectural study be undertaken by the VOA that would support the implementation of this type of capability to provide its NSEP communications. AWARENESS OF NATIONAL SECURITY EMERGENCY PREPAREDNESS PLANNING Survivability of communications links poses another major challenge. The VOA is one of the 22 federal agencies designated to participate in NSEP telecommunications. NSEP telecommunications systems are designed specifically to be survivable. In addition, they are being designed to meet the critical, communications needs of leadership functions of the government, including post-nuclear-attack restoration. The VOA should monitor NSEP telecommunications plans actively to ensure that its needs are being considered and included. As part of its participation in the NSEP program, the VOA should take advantage of the emergency preparedness planning activities of the Department of Defense, especially those being initiated as a result of recommendations by the President’s National Security Telecommunications Advisory Committee (NSTAC). The NSTAC was established by the Reagan Administration to provide advice to the President on telecommunications matters related to our national security. Through NSTAC-initiated studies, recommendations are being provided regarding means to enhance NSEP telecommunications. One of the recommendations adopted was the formation of the National Coordinating Center (NCC), manned by representatives of the telecommunications industry and federal government agencies participating in the National Communications System. The NCC is a focal point for planning to address real-time crises and to provide a means to coordinate NSEP activities among the

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telecommunications carriers and the government agencies. While many independent initiatives are being undertaken by each of the participating federal agencies, cooperative initiatives and planning by the NCC provide a forum through which all participants can benefit from individual, emergency preparedness programs. The VOA’s participation in the NCC would provide an opportunity to take part in day-to-day emergency-preparedness planning, procedure preparation, and real-time exercises. This participation also would provide VOA access to representatives of the agencies, operating companies, and organizations primarily responsible for restoring communications during a national emergency or crisis. Developing a closer, working relationship with the Federal Emergency Management Agency (FEMA) would also be useful, since the VOA’s emergency preparedness plans must address the issues of logistics and the provision of facilities and consumables such as fuel, food, water, and supplies. The VOA could acquire useful information from FEMA plans and supplement them, where necessary, to meet its own specific needs. In the domestic situation, emergency preparedness plans for the VOA should interface with those of FEMA. It would be helpful to the VOA to use FEMA capabilities to establish emergency links to domestic relay stations from both Washington and alternative operations sites, or to earth stations that would link domestic VOA operations with those of foreign relay stations. But the VOA should not depend solely on the capabilities of FEMA. It should also have prepared backup links itself. The VOA is uniquely able to provide such links, in part by using its own HF capability. This capability should be provided at each domestic VOA site, with a set of frequencies selected in advance for emergency transmissions to relay stations, and for program feeds to these stations. RECOMMENDATIONS The VOA has a critical role in communicating the U.S. government’s policies to the outside world over a full range of crises. Therefore, its emergency preparedness plans must consider the survivability of facilities, people, communications links, and logistics—not simply the survivability of a single, backup, broadcast facility. The Committee recommends ten measures to help the VOA achieve this goal: 1. The VOA should have a clearly articulated, emergency mission statement based on a definition of emergency that will trigger appropriate responses. This statement should be applicable to all levels of VOA personnel and operations. 2. The VOA should not rely on the United States Information Agency for emergency-planning guidance; instead, it should seek the authority to designate a VOA principal as a representative to the Committee of Principals of the National Communications System. 3. The VOA should adopt a systems approach to developing its emergency preparedness plans. That approach considers the

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4.

5.

6.

7.

8.

9.

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interrelationship of facilities, people, communications links, electric power, organizational structure, and logistics and develops an emergency preparedness system in which these interrelationships may be optimized. The VOA system should be survivable, endurable, flexible, and ingenious. These attributes pertain to the total system and guide the design of the systems supporting day-to-day VOA operations. The VOA should develop emergency plans to meet these systemic requirements that are clear, direct, and simple and that can be implemented by a single authority. To ensure survivability of facilities, the VOA should plan for a mix of fixed, mobile, and cooperative facilities. Many cooperative facilities could be created with the installation of a small equipment complement to meet the VOA’s unique needs at existing studios and transmitter sites. Commercial broadcast studios or college campus studios could offer an alternative to implementing backup VOA studios. Alternative emergency news sources should also be identified. High-altitude nuclear detonation presents a special challenge for the protection of electronics systems and high-frequency (HF) propagation. Good engineering design and implementation practices may generally suffice to reduce high-altitude electromagnetic pulse (HEMP) vulnerability. The effect of HF propagation outages can be mitigated by equipping alternative transmitter sites, distributed so that some will presumably be outside the detonation area, with low-cost, receive-only satellite terminals to receive broadcast material relayed via satellites from VOA centers affected by HF propagation disturbances. But the VOA should guard against total inoperability, even of alternative sites, by providing them with standby power-generating facilities and the fuel to run them for extended periods. To ensure availability of communications links, the VOA should implement alternative satellite communications capabilities and directly participate as the United States Information Agency representative in the National Security Emergency Preparedness (NSEP) program to ensure that VOA telecommunications system requirements are included. The VOA should monitor the NSEP telecommunications systems implementation to ensure that its requirements are being met. To meet this recommendation the Committee believes that the VOA will have to become a member of the NSEP Committee of Principals and should seek USIA authority to do so. The VOA should consider partial relocation of its technical systems and technical staff from the Washington, D.C. area to more suitable sites, preferably with geographic dispersion. With the communications resources available today, colocation of policy and technical functions is no longer required. Relocation of technical functions, including translation to a remote site, will reduce expenses during peacetime and enhance survivability under disaster scenarios. The VOA should ensure continuing links between its technical centers and relay sites using developed HF capability or satellite links. Since multiple, large-scale, backup facilities would be prohibitively costly, serious consideration should be given to the

Antennas, Satellite Broadcasting, and Emergency Preparedness for the Voice of America, National Academies Press, 1999. ProQuest Ebook Central,

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relocation of primary VOA operational facilities in areas of minimum vulnerability. 10. The VOA’s emergency preparedness plans also should consider standby power, food, water, fuel, and other consumables so that operations can continue for extended periods without resupply. REFERENCES National Research Council. 1985. The Policy Planning Environment for National Security Telecommunications: Annual Report to the National Communications System. Washington: National Academy Press. National Research Council. 1986. The Policy Planning Environment for National Security Telecommunications: Final Report to the National Communications System. Washington: National Academy Press.

Antennas, Satellite Broadcasting, and Emergency Preparedness for the Voice of America, National Academies Press, 1999. ProQuest Ebook Central,

Copyright © 1999. National Academies Press. All rights reserved.

About this PDF file: This new digital representation of the original work has been recomposed from XML files created from the original paper book, not from the original typesetting files. Page breaks are true to the original; line lengths, word breaks, heading styles, and other typesetting-specific formatting, however, cannot be retained, and some typographic errors may have been accidentally inserted. Please use the print version of this publication as the authoritative version for attribution.

GLOSSARY

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GLOSSARY

AED: AFRTS: AM: AOA: BBC: dB: DBS: DBS-A: EHF: EMP: FEMA: FM: GHz: GWEN: HEMP: HF: INSAT: IONCAP: IONSUM: ITU: km: kW: LPC: MW:

Analysis, experiment, and development Armed Forces Radio and Television Services Amplitude modulation Angle of arrival British Broadcasting Corporation Decibel Direct broadcast satellite Direct audio broadcasting by satellite Extremely high frequency Electromagnetic pulse Federal Emergency Management Agency Frequency modulation Gigahertz Ground Wave Emergency Network High altitude electromagnetic pulse High frequency Indian National Satellite Ionospheric Communications Analysis and Prediction, a computer program Acronym standing for IONCAP SUMmary, a computer program International Telecommunication Union, an organization of the United Nations Kilometer Kilowatt Linear predictive coding Medium wave

Antennas, Satellite Broadcasting, and Emergency Preparedness for the Voice of America, National Academies Press, 1999. ProQuest Ebook Central,

Copyright © 1999. National Academies Press. All rights reserved.

About this PDF file: This new digital representation of the original work has been recomposed from XML files created from the original paper book, not from the original typesetting files. Page breaks are true to the original; line lengths, word breaks, heading styles, and other typesetting-specific formatting, however, cannot be retained, and some typographic errors may have been accidentally inserted. Please use the print version of this publication as the authoritative version for attribution.

GLOSSARY

NASA: NCC: NCS: NSDD: NSEP: NSTAC: OMNCS: PN: RF: SHF: STLs: SW: TCI: UHF: USIA: VALSUM: VHF: VSWR: WARC:

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National Aeronautics and Space Administration National Coordinating Center National Communications System National Security Decision Directive National Security Emergency Preparedness National Security Telecommunications Advisory Committee Office of the Manager, National Communications System Pseudo noise Radio frequency Super high frequency Studio to transmitter links Short wave Technology for Communications, International Ultra high frequency United States Information Agency VALidation SUMmary, a computer program Very high frequency Voltage standing wave ratio World Administrative Radio Conference

Antennas, Satellite Broadcasting, and Emergency Preparedness for the Voice of America, National Academies Press, 1999. ProQuest Ebook Central,

Copyright © 1999. National Academies Press. All rights reserved.

About this PDF file: This new digital representation of the original work has been recomposed from XML files created from the original paper book, not from the original typesetting files. Page breaks are true to the original; line lengths, word breaks, heading styles, and other typesetting-specific formatting, however, cannot be retained, and some typographic errors may have been accidentally inserted. Please use the print version of this publication as the authoritative version for attribution.

GLOSSARY

Antennas, Satellite Broadcasting, and Emergency Preparedness for the Voice of America, National Academies Press, 1999. ProQuest Ebook Central,

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