SMALL SATELLITE APPLICATIONS OF COMMERCIAL OFF THE SHELF RADIO FREQUENCY INTEGRATED CIRCUITS A Thesis by JOHN THOMAS GRAVES Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE December 2011 Major Subject: Aerospace Engineering Small Satellite Applications of Commercial Off the Shelf Radio Frequency Integrated Circuits Copyright 2011 John Thomas Graves SMALL SATELLITE APPLICATIONS OF COMMERCIAL OFF THE SHELF RADIO FREQUENCY INTEGRATED CIRCUITS A Thesis by JOHN THOMAS GRAVES Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved by: Chair of Committee, Helen Reed Committee Members, Alan Palazzolo Ana Goulart Head of Department, Dimitris Lagoudas December 2011 Major Subject: Aerospace Engineering iii ABSTRACT Small Satellite Applications of Commercial Off the Shelf Radio Frequency Integrated Circuits. (December 2011) John Thomas Graves, B.S. Aerospace Engineering, Texas A&M University Chair of Advisory Committee: Dr. Helen Reed Within the first decade of the 21st century, the aerospace community has seen many more opportunities to launch small spacecraft in the 10 to 100 kg mass class. Coupled with this has been consistent interest from the government in developing small-spacecraft platforms to expand civil and military mission possibilities. Small spacecraft have also given small organizations such as universities an increased access to space. Because small satellites are limited in size, power, and mass, new and often nontraditional capabilities must be explored and developed to make them viable and attractive when compared with larger and more proven spacecraft. Moreover, small organizations that wish to contribute technically are often limited by the small size of their teams and available resources, and need creative solutions for meeting mission requirements. A key need is in space-to-ground communications. Complex missions typically require large amounts of data transfer to the ground and in a timely fashion. Available options trade hardware cost, available ground stations or networks, available operating-frequency range, data-rate performance, and ease of use. A system for small spacecraft will be presented based upon Radio Frequency Integrated Circuits (RFIC) that minimizes development effort and maximizes interface control to meet typical small- spacecraft communications requirements. RFICs are low-cost components that feature pre-built radio hardware on a chip that can be expanded easily by developers with little or no radio experience. These devices are widespread in domestic applications for short-range connectivity. iv A preliminary design and prototype is presented that meets basic spaceflight requirements, offers data rates in the 55 to 85 kbps range, and has completed basic proof-of-concept testing. While there are higher- data-rate alternatives in existence, the solution presented here strikes a useful balance among data rate, parts cost, and ease of use for non experts, and gives the user operational control necessary to make air-to- ground communications time effective. v DEDICATION To my parents for getting me to this point and to my wife who supported me through it all vi ACKNOWLEDGEMENTS I would like to thank the services and advice of my committee members Dr. Palazzolo and Dr. Goulart throughout the thesis development and defense process. I owe a great deal to Colleen Leatherman and Karen Knabe for support from within the Aerospace Department to navigate all matters of business and administration during this thesis process. They have always brought common sense, effort, and clever solutions to any difficulty I have had in the process. All engineering and practical matters relating to this thesis development could not have been completed without the help of Joseph Perez, who brought years of experience working on spacecraft of all shapes and sizes to bear. His mentorship taught me how to leap from paper development and into real hardware. I doubt very much I could have made any of my efforts and plans functional without his tutelage and focus on discipline, careful and deliberate methodology when working in the laboratory, and extensive advice on any practical matters I happened to be unfamiliar with. Finally, and most importantly, I would like to thank my committee chair, graduate advisor, colleague, and friend, Dr. Helen Reed. She has been the prime force behind my work since I was a sophomore working on my Bachelor’s degree. She came to Texas A&M in 2004, with a desire to establish a student satellite laboratory based upon her successful work at Arizona State University. I met her in December of 2004 asking how I could be involved, and she was able to take my interest at the time, and transform it into an amazing set of experiences, work, learning, and partnerships. During this time I have been allowed to contribute to help put Texas A&M at the forefront of space engineering through its own indigenous spacecraft programs, grow as a leader, take on a graduate education, and add amazing depth and dimension to my experiences at Texas A&M. She is a tireless champion and supporter of her student’s dreams and ideas, and none of what I have accomplished would have been possible without her. vii TABLE OF CONTENTS Page ABSTRACT ........................................................................................................................................ iii DEDICATION .................................................................................................................................... v ACKNOWLEDGEMENTS ................................................................................................................ vi TABLE OF CONTENTS .................................................................................................................... vii LIST OF FIGURES ............................................................................................................................. ix LIST OF TABLES .............................................................................................................................. xi I. INTRODUCTION ....................................................................................................................... 1 A. University Programs ................................................................................................... 2 B. AggieSat Lab .............................................................................................................. 2 C. The Goal: Improvement in Communications Subsystems ......................................... 4 D. Current Alternatives ................................................................................................... 5 E. The Proposed Solution: Radio Frequency Integrated Circuits ................................... 7 II. EXISTING SYSTEMS AND ALTERNATIVES ........................................................................ 10 A. Amateur Radio Systems ............................................................................................. 14 B. Custom Systems ......................................................................................................... 15 C. Commercial Wireless Modem Systems ..................................................................... 20 D. The RFIC Thesis Project ............................................................................................ 25 III. SYSTEM OBJECTIVES AND REQUIREMENTS DEFINITION ............................................. 26 A. System Objectives ...................................................................................................... 26 B. System Requirements ................................................................................................. 28 IV. SYSTEM CONCEPT DEFINITION ........................................................................................... 30 A. RFIC Device Trade Space and Selection ................................................................... 30 B. The Texas Instruments CC1101 Radio Frequency Integrated Circuit ........................ 34 C. System Concept .......................................................................................................... 37 D. Microcontroller Selection ........................................................................................... 44 V. PRELIMINARY DESIGN DESCRIPTION ................................................................................ 47 A. Hardware Design ........................................................................................................ 47 B. Software Design ......................................................................................................... 49 C. Development Summary .............................................................................................. 53 viii Page VI. VERIFICATION PLAN .............................................................................................................. 57 A. Link Budget Description ............................................................................................ 59 B. Data Rate Budget Description .................................................................................... 59 C. Frequency Error Analysis Description ....................................................................... 59 D. Basic Functional Testing Description .......................................................................