Design and Implementation of Low Cost Optical Telemetry

Design and Implementation of Low. Cost 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. 4 in x 1. 2 in x 1. 14 in volume Weigh under 200 g Easily integrate into Polar Cube Withstand at least 20 g’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 Data Handling (CDH)

Overview/Requirements • CDH is handled with an AVR ATmega 1284 P microcontroller. • CDH shall be able to handle image data streaming up 1 Mbps 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 Interface SPI Microcontroller ATmega 1284 P One. Wire Interface Temperature Sensors (x 3) JPEG Data Stream 8 -bit parallel Command Interface I 2 C Camera Module Aptina MT 9 T 111

Image Capture Flow Picture Trigger • • • 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 • • 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 JPG 100 JPG 90 3. 1 MP 1. 0 MB 2048 x 1536 504. 4 KB With a 256 MB 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 5 V to the microcontroller. • Will use 3. 3 V from Polar. Cube to power the voltage regulator, DC-DC converter, and memory module. • Will provide 2. 8 V and 1. 8 V 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 Burn. Down 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 12 -Mar CANCELED 2 -Apr Date 14 -Feb 15 -Feb 25 -Feb 4 -Mar 11 -Mar 12 -Mar 8 -Apr 14 -Feb 24 -Feb 25 -Feb 27 -Feb 11 -Mar

Electrical Item 1 st board & parts ordered Date met Status 14 -Feb board and testing setup assembled Testing: electrical, microcontroller, camera Board v 2 designed 22 -Feb 27 -Feb 27 -Mar 28 -Feb 27 -Mar Board v 2 ordered & parts ordered Board v 2 assembled Board v 2 electrical testing 27 -Mar 8 -Apr 9 -Apr 27 -Mar 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 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