Satellite Communications Physics
BY MEMBERS OF THE STAFF OF BELL TELEPHONE LABORATORIES EDITOR: RONALD M. FOSTER, Jr.
How scientists and engineers use basic physical principles to solve some of the problems in communicating by means of man-made satellites
© 1963 Bell Telephone Laboratories, Incorporated
All rights reserved. Permission to reproduce any material contained in this book must be obtained, in writing, from the publisher.
Library of Congress Catalog Card Number 63-21667
Printed in U.S.A.
John R. Pierce Executive Director, Research, Communications Principles and Communications Systems Bell Telephone Laboratories
When I first talked about the possibilities and advantages of communications satellites to the Princeton Section of the Institute of Radio Engineers on the evening of October 14, 1954, I was diligent in my analysis and enthusiastic in my presentation but, I must confess, a little skeptical as to whether or not anything would come of the idea.
Still, others and I at Bell Laboratories remained interested, and, after the launching of Sputnik I on November 3, 1957, and of Explorer I on January 31, 1958, we worked actively toward satellite communications experiments. This led to our work with Echo I (launched August 12, 1960) and finally to the launching on July 10, 1962, of Telstar I—that satellite which became, in the words of Queen Elizabeth, “the invisible focus of a million eyes.”
This work on communications satellites has been a grand exploration and opening up of a hitherto dark continent of science and technology. My courageous friends at Bell Laboratories encountered therein surprising difficulties and perplexing problems which I had never dreamed of, and these intrepid and indefatigable adventurers grappled with them and mastered them all.
Now you, who have in your own homes seen pictures transmitted across the ocean by satellite, can learn first hand from the men who worked on hard and varied technical problems just what these problems were and how they were solved. And, by reading you can find out what sort of knowledge, training, and habits you yourself will need if you wish some day to adventure into those undiscovered or unexplored fields of technology which will be new and exciting when Telstar has become old hat.
Unknown
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Satellite Communications Physics
Foreword
Contents
Introduction
Why Do We Bother With Satellite Communications?
What a Communications Satellite Can Do
The Road to Successful Satellite Communications
What About the Future?
Project Telstar
What Project Telstar Was Designed To Do
The Telstar I Satellite—Outside
The Telstar I Satellite—Inside
Ground Stations for Satellite Communications
The Satellite Goes Into Orbit
The Second Telstar Satellite
How the Telstar Satellite Works
Some Big Problems in Satellite Communications
Types of Satellite Orbits
Six Typical Problems
At the Foundation: Basic Physical Principles
Problem-Solving Techniques
THE PROBLEM
How We Track Satellites
The Basic Physics of Satellite Motion
Calculating the Orbit of Echo I
Calculating the Orbit of Telstar I
THE PROBLEM
The Radiation of Heat
Absorptivity and Emissivity
How We Measure the Radiation of Heat
Finding the Right Surface for Telstar
THE PROBLEM
Why We Want to Know About the Spin Axis
Ways of Measuring the Spin Axis
Locating the Mirrors on the Satellite
How We Record Flashes from the Mirrors
Results
THE PROBLEM
Organizing the Work
Technical Background on Solar Cells
Finding Out About Radiation Damage
Designing and Making the Best Solar Cells
Mounting the Cells on the Satellite
THE PROBLEM
How a Synchronous Satellite Would Work
The Effects of Time Delay
The Echo Problem
Experimenting With Pure Delay
Designing the Experiment
What Should We Observe?
The Results and What They Mean
Length of Time Before Seven Pairs of Talkers Could Detect 1.2 Seconds of Delay
THE PROBLEM
The Telstar Command Circuit
The Fifteen Telstar Commands
What Went Wrong With Telstar I
Looking for the Trouble Spot
The Villain: Radiation
Fooling the Decoder
Removing the Ionization
Back to Normal—For a Time
A Final Note to the Reader
Suggested Reading
Satellite Communications
Project Telstar
Satellite Communications Case Histories
The Editor
Footnotes
Transcriber’s Notes