Volume 21 Number 1, Spring 1991 COMSAT TECHNICAL REVIEW Advisory Board Joel R
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COMSAT Technical Review Volume 21 Number 1, Spring 1991 COMSAT TECHNICAL REVIEW Advisory Board Joel R. Alper Joseph V. Charyk Volume 21 Number 1, Spring 1991 John V. Evans John. S. Hannon Editorial Board Richard A. Arndt, Chairman I EDITORIAL NOTE S. Joseph Campanella S. B. Bennett AND G. Hyde Dattakumar M . Chitre William L. Cook INTELSAT VI: Spacecraft Design Calvin B. Cotner Allen D. Dayton 5 INTELSAT VI SPACECRAFT BUS DESIGN Russell J. Fang L. R. Dest, J-P. Bouchez, V. R. Serafini , M. Schavietello AND Ramesh K. Gupta K. J. Volkert Michael A. Halley Edmund Jurkiewicz 7 ALTITUDE AND PAYLOAD CONTROL SYSTEM FOR INTELSAT VI Ivor N. Knight L. 1. Slafer AND V. L. Seidenstucker Alfred A. Norcott Hans J. Weiss 101 INTELSAT VI COMMUNICATIONS SUBSYSTEM DESIGN Amir I. Zaghloul G. N. Horvai, L. A. Argyle, T. L. Ellena , R. R. Persinger AND Past Editors Pier L. Bargellini, 1971-1983 C. E. Mahle Geoffrey Hyde, 1984-1988 Editorial Staff MANAGING EDITOR 149 THE INTELSAT VI ANTENNA SYSTEM Margaret B. Jacocks R. R. Persinger , S. O. Lane, M. F. Caulfield AND A. I. Zaghloul TECHNICAL EDITOR AND Barbara J. Wassell 191 INTELSAT VI ON-BOARD SS-TDMA SUBSYSTEM DESIGN PRODUCTION PERFORMANCE Barbara J. Wassell R. K. Gupta , J. N. Narayanan, A. M. Nakamura, F. T. Assal AND Virginia M. Ingram B. Gibson N . Kay Flesher Ladd Morse Non-INTELSAT V1 Papers CIRCULATION Merilee J . Worsey 227 HIGH-EFFICIENCY SINGLE RIDGED 16-WAY RADIAL POWER COMBINER M. Oz, B . D. Geller, P. K. Cline AND I. Yogev COMSAT TECHNICAL REVIEW is published by the Communications Satellite Corporation (COMSAT). Subscriptions, which include the two issues published for a 253 TRANSLATIONS OF ABSTRACTS calendar year, are: one year, $20 U.S.; two years, $35; three years, $50; single copies, FRENCH 253 SPANISH 256 $12; article reprints, $3. Overseas airmail delivery is available at an additional cost of $18 per year. Make checks payable to COMSAT and address to Records Department. 259 AUTHOR INDEX, CTR 1990 Communications Satellite Corporation, 22300 Comsat Drive, Clarksburg, MD 20871- 9475, U.S.A. 261 INDEX OF 1990 PUBLICATIONS BY COMSAT AUTHORS ISSN 0095-9669 267 PAPERS SCHEDULED FOR PUBLICATION IN TILE CTR INTELSAT VI © COMMUNICAT'IONS SATELLITE CORPORATION 1991 SERIES COMSAT IS A IRADE MARK AND SERVICE MARK OF THE COMMUNICATIONS SATELLITE CORPORATION 11 II Editorial Note S. B. BENNETT, Guest Editor, INTELSAT G. HYDE, Associate Guest Editor , COMSAT This is the second volume of the COMSAT Technical Review (CTR) dedi- cated to the INTELSAT VI satellite and system. Because of the importance and complexity of the INTELSAf VI satellite and its associated system operation, three volumes of CTR are needed to fully document the process leading to its very successful implementation. These volumes cover the subject from con- cept, through design and test, to in-orbit operation. Related fourth and fifth volumes will address system applications and the implementation of satellite- switched time-division multiple access (Ss-TDMA). Compilation of these vol- umes is a joint effort of COMSAT and INTELSAT, including co-editors from each organization. The first volume in the CTR INTEL AT VI series* described the overall development process, as well as system planning, specification of the space- craft bus and communications payload, and the design for SS-TDMA and FDMA services. This second volume focuses on the design of the INTELSAT VI spacecraft and its communications payload. The first paper deals with design of the spacecraft bus, including the spun and despun sections, structures, thermal control, mechanical design, deployment mechanisms, power subsystem. te- lemetry and command, propellant systems, and beacon tracker subsystem. The second paper covers the attitude and payload control system. including descriptions of the design and performance of the microprocessor-based con- trol system, despun platform pointing control, active notation stabilization, fault protection, and control autonomy. A design overview and description of the communications payload are provided in a third paper, with emphasis on the receivers, filters, switch networks, and power amplifiers. Paper four details the design, implementa- tion, and testing of the antenna system, including the C-band dual-polarized, hemi/zone transmit and receive antennas; the east and west steerable Ku- band spot beam antennas; the C-band dual-polarized global coverage horns; the antennas used for telemetry, command, and beacon on-station; and the omnidirectional antennas used for telemetry and command in transfer orbit. The last paper in this volume discusses the design and implementation of the *Refer to pages 267 through 271 of this issue for a listing of the papers scheduled for publication in this series. Papers on other topics are also included. 1 2 COMSAT TECHNICAL REVIEW VOLUME 21 NUMBER I, SPRING 1991 EDITORIAL NOTE 3 on-board SS-TDMA package, including the switching system, the digital con- Simon B. Bennett received a B.E.E. from City College trol unit, timing control, and operation. of New York in 1959 and an M.E.E. from New York Univer- The third volume in the INTELSAT VI series will cover a wide range of sity in /961 . His career, which spans the entire history of topics, including measures taken to ensure a reliable satellite; the launch, communications satellites, began with work on the first deployment, and in-orbit testing phases; and operation of the satellite in orbit. TELSTAR satellite program at Bell Telephone Laborato- Presented in a related fourth volume on the INTELSAT system and applica- ries from 1959 to 1963 . He continued in this field at tions will be papers on earth station considerations , as well as on digital, COMSAT from 1961 to 1974, where he contributed to the video, and other modulation coding techniques used in the INTELSAT vi era. success of satellite programs from Early Bird to The fifth volume will be devoted to describing all aspects of the SS-TDMA INTELSAT IV. Since 1974 he has been at INTELSAT, where he has been manager of spacecraft programs, directed sys- system, which was first used for commercial purposes on tNTELSAT VI. tems planning studies, and managed the operation of The editors trust that this comprehensive treatment of the INTELSAT VI INTELSAT's 15-satellite fleet (including the INTELSAT Vl series). He is currently system will prove useful to future system planners. The papers in this and Assistant to the Vice President for Engineering and Research. subsequent volumes are the result of a major effort by a large group of authors from COMSAT, INTELSAT, and Hughes Aircraft Corporation, and we con- gratulate them on their substantial achievement. Geoffrey Hyde received a B.A. Sc. in engineering physics and an M.A.Sc. in electrical engineering from the University of Toronto in 7953 and 1959, respectively, and a Ph.D. in electrical engineering from the University of Pennsylvania, Philadelphia, in 1967. Prior to joining COMSAT Laboratories in July 1968, he worked on anten- nas, microwaves, and propagation at RCA, Moorestown, NJ, and at Avro Aircraft Company and Sinclair Radio Labs in Canada. At COMSAT prior to 1974, Dr. Hyde was concerned with the development of the torus antenna, a general an- tenna analysis computer program (GAP), and related areas of endeavor. In February 7974 he became Manager of the Propagation Studies Department , where his work included a wide variety of efforts in propagation measurement and analysis . In 7980 he joined the .staff o/ the Director, COMSAT Laboratories, and in 1984 became Assistant to the Director. His duties included coordination of the COMSAT R&D programs, coordination of ITU activities at COMSAT Laboratories , and editorship of the COMSAT Technical Review. In June 1989 he retired, and is currently a consult- ant to COMSAT Laboratories. Dr. Hyde is a member of URSI Commissions B and F, and the AIAA, and is a Registered Professional Engineer in Ontario, Canada. His honors include David Sarnoff Fellowships (1965 and 1966), Fellow of the IEEE (1987), and the IEEE G-AP award for best paper, 1968 (jointly with Dr. Roy C. Spencer). Index: attitude control , communication satellites, INTELSAI. propulsion, thermal control INTELSAT VI spacecraft bus design L. R. DEST, J-P. BOUCHF7., V. R. SERAFINI, M. SCHAVIETELLO, AND K. J. VOLKERT (Manuscnpi received October 18, 1990) Abstract The spin-stabilized INTELSAT VI spacecraft bus is described, including overall design requirements and individual subsystems. The satellite weighs approximately 4,500 kg at launch, has a beginning-of-life mass of 2,570 kg, and an end-of-life dry mass of 1,905 kg. It is composed of spun and despun sections connected by a bearing and power transfer assembly. The despun section structure supports the communica- tions payload (repeater and antennas) and provides the command and telemetry and thermal control functions. The spun section includes the attitude control, power, pro- pulsion, and thermal subsystems. Deployable appendages, including antennas and a telescoping solar panel, are implemented by multiple mechanisms. Introduction The spacecraft design that evolved to meet the INTELSAT VI specifica- tions [I] was considerably different than the conceptual spacecraft designs INTELSAT (supported by COMSAT Laboratories) generated 121 prior to release of the request for proposals for INTELSAT VI in 1980. Because of the significant power necessary to support the defined INTELSAT VI payload, the stringent antenna pointing performance required to meet the hemi/zone an- tenna specifications, a 10-year design lifetime, and launch vehicle mass and volume constraints, it was assumed that only a contemporary three-axis- stabilized spacecraft would be suitable. Quite surprisingly, Hughes Aircraft Company (HAC) proposed a scaled-up version of a spin-stabilized spacecraft that combined concepts dating back to the early 1970s (which had been included in the TACSAT and INTELSAT IV/IV-A designs) with newer technology employed on the HAC LEASAT "widebody" Shuttle Transportation System 5 SPACECRAFT BUS DESIGN 7 6 COMSAT TECHNICAL REVIEW VOL UME 21 NUMBER I, SPRING 1991 (STS) optimized design and the telescoping solar array developed for the small HAC HS-376 domestic satellites.