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Beagle Bone Black and Flight Computer
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This page serves as a record of current and past research flying as DREAMS payloads.
High altitude balloons take a cross section of the thickest parts of the Earth's atmosphere until they degrade and burst. Temperatures get as cold as -60 deg C and pressure can get below 1% of normal atmospheric pressure. Maximum altitudes for DREAMS flights vary from 70,000 ft to 118,500 feet depending on type of balloon and ascent rate. Flight time is typically kept low to minimize range and recovery time where flights have varied from 1 hour 15 minutes to 2 hours 15 minutes.
Remote Sensing with D17 Images
A still camera can be flown aiming downward to take downward looking satellite type images. These images can be compared to images on Google Earth, and other satellite images like those from LandSat. These comparisons can show changes in land features to include water levels, plant growth, tree coverage, etc.
Temperature sensors can be placed inside or outside of the payload boxes. The current configuration can place up to 13 temperature sensors in the secondary payload box. Eleven of those temperature sensors are currently TMP36 solid state sensors that stop working at -50 deg C. If the box is not exposed to the outside with any gaping holes, it will remain up to 30 deg warmer.
Spec Sheets on Temp Sensors Flying
Calibration Data. Each sensor was dipped into an ice bath that was between 1.6C and 2.7C at the bottom but sensors were place in the top. Each sensors was then placed in hot water at varying temperatures. The temp of the hot water in order of sensor (0,1,2,3,4,5,6,7,10,11,12,13,14,15) was 67.4,65.2,64.2,63.7,63.1,62.1,61.6,61.0,60.2,59.3,58.6,58.0,57.5,57.0. All sensors were bundled together and put in the hot water together at 55.0C. The sensors were finally placed in the ice water together at 2.3C (at the bottom). The ambient temp of the air was 22.6C. The file below has the TMP36 data converted to Celsius, Three TMP36 sensors started well but maxed out which may have occurred if water got to the wires but this has not been tested yet. The platinum RTD's were limited in range but performed very well.
Channel 0,1,3,5,6,7,10,11,12,13,14,15 = TMP36
Channel 2,4 = RTD
Channel 7,8 = RH, Temp
Signal Conditioning for RTDs
Using a Zero Tempco
circuit for signal conditioning (with 1N457, 134 ohm, and 1340 ohm resistor)
Research Project: Dr. Madock's Temperature Altitude Experiment
Relative Humidity is recorded on the same set of channels recording the temperature.
Below is a screen shot of some of TMP36 data from the DREAMS-17 flight. The actual data with some plots are included.
Data Analysis was also done in Mathematica, just for a bit of experimentation with the software, testing its viability for future data analysis.
DataAnalysis of D17TempData.nb
A Geiger-Muller tube will fly pointing toward the sky for the D18 flight. As a calibration, three data points were collected to compare to a calibrated Geiger counter. More data points are needed and more data to improve the calibration, but it appears to be mostly linear between the source offset by a constant. Real counts per minute = 10.4 x Raw count with R^2 = 0.89. Calibration file is below.
Three OPT301 photo diodes are mounted to the top of the secondary payload box. They each have band pass filters that allow only certain wavelengths of light to pass through.
L1: 250nm - 400nm
L2: 400nm - 700nm
L3: 700nm - 1100nm
GPS Data Logger
There is a dedicated GPS data logger that will save multiple GPS NMEA sentences at 1 per second. This data will show the wind patterns in the upper atmosphere that the balloon travels. The recent Google Loon Project controls its altitude so it can ride these winds to hover over an area -- CSP/DREAMS alum and MIT undergrad Erin King has been working on this project as a Google intern. Here is more information:
An Op-Amp circuit with a voltage reference of voltage divide can be used to amplify a sensor output and shift its output by a certain amount. This is necessary if your data logger can only measure in a certain range, like 0-5V for an Arduino Uno.
The following program files are the Arduino code that runs on each data logger. Libraries are also included. The Arduino IDE is available from free
Arduino Code (Downloads - Right-click to save)
Generic Data Logger
Pressure and Light Sensors
Arduino Libraries (unzip to libraries folder)
Real Time Clock:
help on how to format text
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