Design and Implementation of LowCost Optical Telemetry to Support
Radiometric Analysis of the
Atmosphere
University of Colorado at Boulder
Alexandra Hickey, Evan Schomer, Rocky
Marcus, and Frank Erdesz
3/14/2013
Mission Overview
• Mini Cam Subsystem on Polar Cube
• Low Cost
• Data confirmation
– Through goe tagging
– Contextual image comparison
• Provides simplified means for post launch
recalibration
2
Design overview
• Three Subsystems
– Structures
– CDH
– Power
• Goal
– Compact
– Easy to interface
– Durable
This Semester
• Worked toward balloon launch
• Not met due to technical difficulties that will
be talked about later by the different
subsystems
Structures
Requirements/Overview
•
•
•
•
•
fit with in a 1.4in x 1.2in x 1.14in volume
Weigh under 200g
Easily integrate into Polar Cube
Withstand at least 20g’s with a factor of safety of two
Maintain all components within operating
temperatures
6
The Design
• PCB structural members
• Stand offs
• Nylon washers
– Prevent moment about the stand offs
• Reinforced holes for stand offs
Command and Data Handling
(CDH)
Overview/Requirements
• CDH is handled with an AVR ATmega1284P microcontroller.
• CDH shall be able to handle image data streaming up 1Mbps
from the image sensor as well as interfacing with memory and
temperature sensors.
• CDH shall write any event or peripheral settings data to nv
memory.
• CDH shall be able to locally store all data for an extended period.
• CDH shall be able to function as a satellite subsystem or
standalone system.
Microcontroller and Peripherals
NV Memory
Memory Interface
SPI
Microcontroller
ATmega1284P
OneWire Interface
Temperature Sensors
(x3)
JPEG Data
Stream
8-bit parallel
Command Interface
I2C
Camera Module
Aptina MT9T111
Image Capture Flow
Picture Trigger
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•
•
•
•
•
Check memory requirements
Prep buffer
Find address location of nv memory
Create image entry/start headers
Set camera settings if necessary
Gather timestamp and other data
Send Camera Capture Command
Receive camera data and store into vram buffer
Check Camera EOF
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•
•
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Load buffer into non-volatile memory
Finish EOF headers on nv memory
Set low power mode on camera/memory
Increment photo ID
Add flight log data (time,settings,name)
Return
Data Storage
Images with a maximum size of 1.0 MB per photo at full
color resolution will be collected. The camera may cycle
through various modes affecting data output size up to
1.0 MB throughout the mission.
Image Size JPG100
JPG90
3.1 MP
1.0MB
2048x1536
504.4KB
With a 256MB memory module, up to 254 images and
supporting mission log data can be stored locally until
uploaded to the main computer memory allowing for a
data transfer to be postponed for an extended period.
Learned
• Processor bus read optimization for large data
transfers.
• Find sufficient documentation for camera
before purchasing.
• Interfacing with a complex and micro sized
camera system and changing various settings
through a command interface.
Power
Power Subsystem Requirements
• Will provide 5V to the microcontroller.
• Will use 3.3V from PolarCube to power the
voltage regulator, DC-DC converter, and
memory module.
• Will provide 2.8V and 1.8V to the camera
module.
Functional Block Diagram
Schematics
Voltage Regulation
Microcontroller – Camera Interface
Lessons Learned
• Improvements on PCB design process
• Learned more circuit debugging strategies
Schedule
Mini Cam BurnDown List
Key
Test
The Whip Test
Drop Test
The Stair Pitch Test
Day in the Life/ Cooler Test
Day in the life/Cooler Test 2
Day in the Life/Vacuum Test
Mechanical
Item
Solid Works Model Finalized
Parts Order for Prototype ordered
Prototype built
Whip test
Drop Test
The Stair Pitch Test
Design Revisions
Retesting
Design Finalized
Final Balloon sat Structure constructed
Met
In Progress
Over Due
25-Feb
25-Feb
25-Feb
25-Feb
25-Feb
25-Feb
12-Mar CANCELED
2-Apr
2-Apr
Date
14-Feb
15-Feb
25-Feb
25-Feb
25-Feb
25-Feb
4-Mar
11-Mar
12-Mar
8-Apr
14-Feb
14-Feb
24-Feb
25-Feb
25-Feb
25-Feb
27-Feb
11-Mar
11-Mar
Electrical
Item
1st board & parts ordered
Date
Date met
Status
14-Feb
14-Feb
board and testing setup assembled
Testing: electrical, microcontroller,
camera
Board v2 designed
22-Feb
22-Feb
27-Feb
27-Mar
28-Feb
27-Mar
Board v2 ordered & parts ordered
Board v2 assembled
Board v2 electrical testing
27-Mar
8-Apr
9-Apr
27-Mar
23-Feb
23-Feb
Last Day to get camera interface board
for reasonable testing time
Camera Working
22-Feb
2-Apr
13-Feb
Last Software Revision for testing
Deadline for software revision
Data anlyzation
5-Apr
5-Apr
19-Apr
CDH
Item
SD Card/Temperature Working
Date
Conclusion
• Will provide a contextual image for geo
tagging and general data confirmation
• Allows for easier resolution of anomalous
readings
• Lowers overall Polar Cube mission risk