DIY Comms and Control for Amateur Space

157 Pages·2015·14.59 MB·English

by  Sandy Antunes

M
a
k Make:
e
Make:
: SPACE-READY
D SYSTEMS
DIY Comms and Control for
I
Y
Amateur Space C DIY Comms and
o
m
m Control for
The picosatellite field has exploded, going from fewer than 10
s
launched per year to over 100 launches halfway through 2015.
a
You no longer need access to a large university or lab to launch n Amateur Space
d
a satellite. Even a motivated high school group can build (and C
launch) one. o
n Talking and Listening
t
Radio spectrum for commanding (and receiving data from) satel- r
o to Your Satellite
lites is a shared resource with subtle hurdles. This book walks the l

f
path originally paved by AMSATs to discuss the steps and licens- o
r

ing needed to set up and operate both a command uplink and a A Sandy Antunes
m
data download station and network. Find out how playing nicely
a
with others maximizes your ability to get your data down. t
e
u
This book will help you:
r

S
p
a
■ Learn the basics of working with radio c
e
Plan out your ground station
■
Understand licensing regulation and requirements
■
Determine your data usage and “link budget”
■ A
n
Design the right antenna for your needs
■ t
u
Prepare to monitor communications and handle anomalies
■ n
e
s
The fourth part of Sandy Antunes’ series for aspiring satellite
builders. Be sure to check out DIY Satellite Platforms, Surviv-
ing Orbit the DIY Way, and DIY Instruments for Amateur Space
before you start sending things up into the skies!
US $9.99 CAN $11.99
ISBN: 978-1-449-31066-0 Make:
Project Book
makezine.com
M
a
k Make:
e
Make:
: SPACE-READY
D SYSTEMS
DIY Comms and Control for
I
Y
Amateur Space C DIY Comms and
o
m
m Control for
The picosatellite field has exploded, going from fewer than 10
s
launched per year to over 100 launches halfway through 2015.
a
You no longer need access to a large university or lab to launch n Amateur Space
d
a satellite. Even a motivated high school group can build (and C
launch) one. o
n Talking and Listening
t
Radio spectrum for commanding (and receiving data from) satel- r
o to Your Satellite
lites is a shared resource with subtle hurdles. This book walks the l

f
path originally paved by AMSATs to discuss the steps and licens- o
r

ing needed to set up and operate both a command uplink and a A Sandy Antunes
m
data download station and network. Find out how playing nicely
a
with others maximizes your ability to get your data down. t
e
u
This book will help you:
r

S
p
a
■ Learn the basics of working with radio c
e
Plan out your ground station
■
Understand licensing regulation and requirements
■
Determine your data usage and “link budget”
■ A
n
Design the right antenna for your needs
■ t
u
Prepare to monitor communications and handle anomalies
■ n
e
s
The fourth part of Sandy Antunes’ series for aspiring satellite
builders. Be sure to check out DIY Satellite Platforms, Surviv-
ing Orbit the DIY Way, and DIY Instruments for Amateur Space
before you start sending things up into the skies!
US $9.99 CAN $11.99
ISBN: 978-1-449-31066-0 Make:
Project Book
makezine.com
DIY Comms
and Control
for Amateur
Space
Sandy Antunes
DIY Comms and Control for Amateur Space
by Sandy Antunes
Copyright © 2015 Sandy Antunes. All rights reserved.
Printed in the United States of America.
Published by Maker Media, Inc., 1160 Battery Street East, Suite 125, San Francisco,
CA 94111.
Maker Media books may be purchased for educational, business, or sales promo-
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Editor: Patrick Di Justo
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Proofreader: Charles Roumeliotis
Interior Designer: David Futato
Cover Designer: Ellie Volkhausen
Illustrator: Rebecca Demarest
June 2015: First Edition
Revision History for the First Edition
2015-05-27: First Release
See http://oreilly.com/catalog/errata.csp?isbn=9781449310660 for release details.
The Make logo and Maker Media logo are registered trademarks of Maker Media,
Inc. DIY Comms and Control for Amateur Space, the cover image, and related trade
dress are trademarks of Maker Media, Inc.
While the publisher and the author have used good faith efforts to ensure that the
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ensure that your use thereof complies with such licenses and/or rights.
978-1-449-31066-0
[LSI]
Contents
Preface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
1/Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Talking to Machines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Parts of a Comm System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Comm for the Impatient. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Two Walkie-Talkies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Flatsat. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Bidirectional Bench Test Hardware. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Power, Range, and Licensing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Higher Power Licensing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Establishing a Ground Network. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Breaking International Law. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Housekeeping Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Housekeeping: Bus and Instrument Are Separate. . . . . . . . . . . . . . . . . . . . 13
Alerts and Pages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Limits Displays: Green, Yellow, Red. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Data Integrity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Requirements Checklist. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Performance Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Security & Anti-Jamming. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Spacecraft Orbits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Frequency Allocation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Physical Constraints. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Architecture Choices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Comparing a Space-Based Network to a Ground-Based Network. . . . . . . . . . 18
NASA’s Tracking and Data Relay Satellite System (TDRSS). . . . . . . . . . . . 18
NASA’s Deep Space Network (DSN). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Near Earth Network. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2/Radio. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Transceiver Concepts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Wavelength and Frequency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Dual Band and Modulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
iii
Doppler. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Interference. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
ADC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Packets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
APRS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Software-Defined Radio. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3/Full Ground Station. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Downlink Only. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Operations Choices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Start with the Mission Payload. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Comm Quantities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Ground Network. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Ranging and Orbit Determination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Ground System Design Products. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Mission Phases. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4/Licensing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Extended Case: Private Comm Sat. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Future Ideas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Regulatory Solutions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
IARU. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Smartphones. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
High-Altitude Ballooning and Guerrilla Radio. . . . . . . . . . . . . . . . . . . . . . . . 57
Demystifying the Basic Technology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Regulatory and Permissions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Ham Technician’s License. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Scenarios. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Safehold. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Ground Sim. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Software. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Compare and contrast. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Relays. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Line of Sight/Direct to Ground. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Relays. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Private Networks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
5/Orbits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Defining Orbits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
The Six Classic Orbital Elements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
TLEs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
iv Contents
Orbit Determination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Satellite Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Ground Tracks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Contact Passes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
6/Comm Budgets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Allocations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Data Priorities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Extended Example of Command via Text Messaging. . . . . . . . . . . . . . . . . 87
More Realistic Bandwidth Allocation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Encoding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Link Budget. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Units. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Link Budget Equation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Going Deeper. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Data Budget. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
7/Antenna Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Antenna Shape. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Common Spacecraft Antenna. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Common Ground Station Antenna. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Antenna Size and Frequency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Impedance and SWR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Antenna Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Power, ERP, and EIRP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
8/Performance Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Data, Error Rates, and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Security. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Historical Satellite Hacking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
9/Concept of Operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
ConOps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
High-Level ConOps Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Ops Center Network. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Trending. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Science Operations Center (SOC). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Science Monitoring. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
Handling Anomalies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
A/Resources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Contents v
Afterword. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
vi Contents
Preface
The picosatellite field has exploded, going from less than 10
launched per year (back in 2009-2011, when I did my Calliope
build) to over 100 launches this year alone. We have gone from
requiring a large university or lab to back a project, to a point
where even a motivated high school can build one. We are in a
Do-It-Yourself (DIY) space age, and I’m proud (maybe even a bit
smug) that Calliope has been part of that. In fact, I’m building
version 2 of my hardware, using advances designed by others
who were, in part, inspired by my Project Calliope!
While waiting for launch, I’ve written these four short DIY satel-
lite books for Make:, each of which has sold several thousand
copies. I get emails from DIY builders of CubeSats and TubeSats
and PocketQubes asking my advice. These emails often start off
with “I was inspired by your project and have a technical ques-
tion about,” followed by a technical question of such complexity
that it’s clear they are already pushing the picosatellite frontier
way past what I did with my little basement-build. There are
CubeSats flying this year that include my work as an inspiration.
I was hired by Capitol Technology University to teach college
students about satellites and systems engineering and physics.
They hired me, to a large degree, because attempting Calliope
impressed them. I am full-time faculty, starting my fifth year
there, and just got promoted to Associate Professor. Because I
haven’t launched yet, and I’m helping college students work
towards their own satellites, I donated the bulk of my ground
station hardware to the not-for-profit Capitol lab I run. This
donated hardware is jumpstarting students’ engagement in top-
ics like ham radio and payload commanding and stuff. My focus
is on what I can do for the next generation of space enthusiasts.
In addition, I’ve become an advocate for the so-called STEAM
movement, that adds an A for Art into the usual STEM curricula.
vii
Life is not a race because the only finishing line is the future, and
that is unknown. So why not be the people that create that
future? Read, think, build, interact, then repeat. As long as you
are moving forward, you are going somewhere.
Conventions Used in This Book
The following typographical conventions are used in this book:
Italic
Indicates new terms, URLs, email addresses, filenames, and
file extensions.
Constant width
Used for program listings, as well as within paragraphs to
refer to program elements such as variable or function
names, databases, data types, environment variables, state-
ments, and keywords.
Constant width bold
Shows commands or other text that should be typed literally
by the user.
Constant width italic
Shows text that should be replaced with user-supplied val-
ues or by values determined by context.
This element signifies a tip, suggestion, or general
note.
This element indicates a warning or caution.
viii Preface