RadSat
TEAM WORK
PHILLIP CROSBY, DAVID HARRISON, BRIAN
FRENCH, MAX PEREZ, DANIEL GALE
Theoretical Overview
 In recent years, scientist have come to a greater
understanding of the effects of carbon-dioxide
emissions, amongst other greenhouse gases, as it
pertains to climate change.
 There exists a theory in the scientific community that
a negative feedback cycle is being created that may
temper some of the effects of climate change.
Atmospheric Feedback
 As greenhouse gasses begin to raise the temperature
of our atmosphere more water vapor is driven into
the atmosphere. The increase in water vapor in turn
generates more clouds and cloud cover. This
increase in cloud cover may block, reflect, and
scatter incoming sunlight – thus slowing the rate of
climate change.
 Further inquiry into whether this phenomenon is
active, and the extent to which it is active, will help
our society to understand our climate and the
manner in which we interact with our climate.
Electromagnetic Absorption
 The primary mechanism that we will use to
investigate this feedback phenomenon will be
gathering atmospheric temperature data using a
radiometer to observe high-frequency spectral
absorptions to monitor and track the Earth’s
temperature from a geosynchronous orbit about the
Earth.
Microwave Sounding
 Due to quantum mechanical effects of airborne
compounds, primarily water vapor and diatomic
oxygen, the Earth’s atmosphere selectively passes
certain bandwidths of electromagnetic radiation
while significantly attenuating others.
Microwave Sounding:
Frequency vs. Zenith Opacity
118.75 GHz
 The atmospheric frequency response surrounding
118.75 GHz offers a unique opportunity to study
from space as it offers a number of advantages:
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Increased frequency resolution as compared to previously
studied absorption bands near 60 GHz
The emitted EM waves are less transparent to clouds
Componentery used to study wavelengths on this level is just
coming into it’s own and this band is largely untapped
Combining data sets with 60 GHz data sets is expected to yield
interesting observations
Vertical Temperature Sounding
Weighting Functions
Interpreting Weighting
Temperature Channels
ALL-STAR
RadSat
Functional Decomposition: Level 0
Antenna
Signal
Processing
ALLSTAR
Functional Decomposition: Level 1
Horn
LNA
Mixer
ANTENNA
Signal
Processing
Detector
Diode
LPF
ADC
BPFs
µC
Physical Design Constraints
 The RadSat will be designed by implementing the 3U
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CubeSat specifications to be connected to the
primary ALL-STAR system housing
The length of the RadSat must be 6.5’’ x 2.5’’ x 2.5’’
The volume of the RadSat must be 40.625 in3.
Must not exceed 2000 g
Center of gravity must be located at the center of the
RadSat.
ALL-STAR System
 ALL-STAR (Agile Low-Cost Laboratory for Space
Technology Acceleration Research)
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Master power and communications delivery platform
Compatible with all 3U CubeSat satellites (including RadSat)
 ALL-STAR Capabilities
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Power distribution to payload (RadSat)
A/D Converters
GPS accuracy within 100 m
Configuration memory 62.5 KB
Data memory 3276.8 MB
Attitude pointing accuracy: 1°
Downlink rate: 250 kbps
Uplink rate: 9.6 kbps
ALL-STAR System
 Communication Handshaking from RadSat to the
ALL-STAR bus
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Serial data will be exchanged using a pin-out connector
Bus capable of transmission rates of 20 mbps
ALL-STAR bus protocol will be used
Error checking bits
 Continuation bit
 Frame number
 Frame length
 Frame data (Timestamp, Response, Type, Opcode, Length,
Message, Checksum)

ALL-STAR Power Constraints
 ALL-STAR Electrical Power System (EPS)
 Delivers 4-5 W of power continuously
 Can deliver 25 W of power for 15 minutes of every orbit
 Voltages available
 Unregulated Battery
 12V
 3.3V
ALL-STAR Programming Concept
 ALL-STAR features will be programmed in C to
accept RadSat packets .
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Address memory management of raw data
Program weighting functions, send temperature data
 Interface between RadSat and MATLAB test surface
via UART to be implemented. MATLAB and C will
be used.
 RadSat’s command and data handling procedures
will be written in C and programmed on the Xmega
microprocessor
Hardware Requirements
 Trigger ADC to sample
 Upwards of 10 channels
 Simultaneous sampling
 16-bit resolution (pin-compatible to 24-bit resolution)
 Process data and pass samples to ALL-STAR
 Acquire a data point at no slower than 2 Hz to
maintain spatial resolution
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Determined by orbital velocity and antenna -3dB angle
 Interface with the ALL-STAR bus
Low Level Objectives
 Raw digital data is collected from RadSat where no
additional data processing will be done.
 The raw data is sent to the ALL-STAR, and no
additional data processing will be done.
Medium Level Objective
 Raw digital data is collected from RadSat where no
additional data processing will be made.
 The raw data is sent to the ALL-STAR where it is
stored and information can be processed to obtain
temperature data to transfer to ground station.
High Objective
 Raw digital data is collected from RadSat where data
will be processed and sent to the ALL-STAR in realtime.
 ALL-STAR receives already processed temperature
data and stores in memory until downlink can be
achieved
Division of Labor
 Brian French
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Matlab test code programming
RF test & assembly
 Maxwell Perez
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Operating system
Programming bus interface
 Phillip Crosby
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Filtering
RF assembly
Documentation
 David Harrison
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Filtering
Sensors: Temperature, Attitude
Power management
 Daniel Gale
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Digital hardware
PCB layouts
firmware
Schedule
Schedule
Milestone 1
Milestone 2
 RF assembly completed
 Calibration systems
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and testing in progress
Digital board nearing
completion
ALL-STAR interface
completed and tested
Firmware complete
First and Second PCB
layouts tested
development in progress
 Third PCB layout and
fabrication complete
 Miniaturization and
Power management
underway for RF
 Data acquisitioning and
conditioning complete
Budget
Provided for us by Space
Grant and Dr. Gasiewski
Component
Mixer
Price
$45,000
RadSat Will Provide
Components
$2000 x 10 $20,000
6
13
78.00
Microprocessor dev environment
1
40
40.00
20
15
300.00
5
12
60.00
ADC
Passives
PCBs
Amplifier
$15,000
Horn
$5,000
Misc. Parts
$10,000
Total
$95,000
Total Cost
Microprocessor
RF Diodes
Filter
Quantity Price
30.00
3
66
198.00
Wire and Connectors
50.00
RF Connectors
50.00
FTDI chips
6
12
72.00
Power regulators
6
5
30.00
Current sensors
6
1
6.00
Temperature sensor
6
1
6.00
30
1
30.00
MOSFETs
TOTAL =
$950.00
Risks & Contingencies
 High power draw
 Table top model will
 Spatial constraints
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exceeded
Finance
Insufficient data capture
High frequency is
difficult to test
Difficult to Demo
Lack of experience with
High Frequency RF
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have no power limit
Table top model will
have no space limit
Space Grant and Dr.
Gasiewski will provide
financial backing
Increase data capture as
much as possible
Use of test facilities at
NIST and possible CU
Labs
Questions?