Student Made Ultraviolet Radiation Detector

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StuMURD
Student Made Ultraviolet Radiation Detector
Presented for your approval by
THE LATE BALLOONERS
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Science Objectives
Through StuMURD, The Late Ballooners will attempt
to approximate the maximum level of UV-B
radiation incident on the earth before being
filtered by Earths ozone layer and other
destructive forces.
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DESIGN

• StuMURD has 4 main systems
• UV Detector System
• Internal Temperature Detector System
• Thermal System
• 4. Mechanical System

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UV Detector System

• Has six subsystems
• 1. Sensor Subsystem
• 2. Data Acquisition Subsystem
• 3. Controller Subsystem
• 4. Data Archive Subsystem
• 5. Switch Subsystem
• 6. Power Subsystem

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Architectural Diagram of UV Detector System
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UV Detector System Sensor Subsystem

• The sensor subsystem is made up of an array of
  four photodiodes calibrated to sense the UV-B
  band of the electromagnetic spectrum (280-320 nm)

SiC - Photodiode JEC 0.3S -spectral range 210 -
380 nm -active area 0.22 mm² -UV-responsivity
0.13 A/W
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UV Detector System Data Acquisition Subsystem
part 1

• Operational amplifiers will amplify the analog
  signal to an ADC that will digitize the analog
  data.

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UV Detector System Data Acquisition Subsystem
part 2

• There will be four separate op amp circuits
  interfacing with the photodiode circuits.

• They will interface to an four-channel
  multiplexing ADC with an 8-bit resolution

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UV Detector System Controller Subsystem

• The controller of the UV Detector system is the
  Basic Stamp. The Data Acquisition subsystem and
  switch subsystem will interface to the Basic
  Stamp through its I/O pins. Each switch will
  require one pin (3 total) and the ADC will
  require between 4-5 pins.

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UV Detector System Data Archive Subsystem

• To maximize the amount of data that can be
  stored, all data will be stored to a 256-kilobit
  EEPROM chip.
• The EEPROM socket is already on the Cansat board
  with a lower capacity EEPROM chip in it. To make
  use of the new 256-kilobit EEPROM chip, the old
  chip only needs to be replaced with the new one
  in the same socket.

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UV Detector System Switch Subsystem

• A series of three on/off switches will be used
  help with data storage and data recovery
• 1. Aquire Data Switch - will allow the
  electronics to begin acquiring and storing data
• 2. Indicator LED Switch - activates the Cansat
  LED and provides visual confirmation that the
  payload is in fact storing data (it will turn off
  to reduce power consumption during flight.)
• 3. Download Data Switch - causes the stamp to
  output all of its stored data to an external file.

The usefulness of these switches will be further
explained in the section dealing with software
implementation.
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UV Detector System Power Subsystem

• Number of batteries is TBD pending completion of
  an accurate power budget. They will interface to
  the power socket on the Cansat board.

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Internal Temperature Detector System

• System is comprised of a HOBO. It is completely
  self-contained and has no interfaces other than a
  dependence on a successful thermal system.
• Only considerations to make are the frequency
  with which to take readings and for how long.

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Thermal System part 1

• For our payload to function throughout the
  duration of the flight, we will need to maintain
  an internal temperature of above 20?C . Our
  main component to keep the payloads temperature
  within this range of operation will be a
  Themo-Pad heat pack. Within the pad is sodium
  acetate. In its liquid state, it be cooled past
  its freezing point which is 54C. However, when
  a metal disk located inside the pack is snapped,
  a crystal forms and starts a chain reaction
  causing the entire pack to jump in temperature up
  to its freezing point 54C (130 F.)

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Thermal System part 2

• Advantages of the Thermo-Pad heat pack
• -pack does not require oxygen which is scarce in
  the upper atmosphere
• -does not present any dangers to electronics
  that liquids do (once it is crystallized)
• -remains at maximum temperature for approximately
  one hour when well insulated and cools to room
  temperature within three to four hours
• -reusable, can be boiled and used again

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Thermal System part 3

• Other thermal considerations will be made with
  the mechanical system design of the payload.
  There will be insulating material on the interior
  of StuMURD to reduce heat loss. Also, there will
  be reflective tape on the exterior to prevent
  overheating due to direct sunlight.

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Mechanical Design part 1

• The mechanical design is in development and a
  finalized payload box will come with increased
  testing and research. Requirements that the box
  must fulfill are as follows
• 1. it must be as small as possible to minimize
  area exposed to the extreme cold temperatures
• 2. should have an inner chamber that is
  insulated, and must be canvassed in reflective
  tape
• 3. must be able to withstand the impact of
  landing
• 4. must be able to withstand very low pressures
  of the upper atmosphere
• 5. It would also be helpful, but not necessary,
  for the payload to be waterproof.

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Mechanical Design part 2 Orientation of Photo
detectors

• There will be four separate photodiodes placed at
  the four upper corners of the payload box. They
  will be angled upwards and placed behind
  protective transparent plates.

• This configuration will assure that at least one
  photodiode will be directly facing the sun,
  regardless of the balloons orientation to the
  sun.

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Software Implementation

• (before running main program, all memory
  locations have been set to zero)
• MAIN
• go to Boot_up subroutine begin infinite loop
• if (Collect_Data switch is ON) AND (Download_Data
  switch is OFF) then
• go to Collect_Data_Loop subroutineif
  (Download_Data switch is ON) AND (Collect_Data
  switch is OFF)then
• go to Download Data subroutine
• end
•  
• Boot_up (safeguards again data overwrite in case
  of power down and then power on again during
  flight)
• Find where data is zero set data_position equal
  to that location to begin writing there
• returnCollect_Data_Loop
• while data_position is less than
  data_position_max then
• Get data from detectors
• Save data to EEPROM memory and increment data
  location
• IF led_indicator switch is on then
• flash indicator LED
• endifpause/sleep loop for TIME_INTERVAL
• Endwhile
•  

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FABRICATION AND TESTING Calibrations

• A detailed plan for calibrations is TBD but will
  involve
• Use of UV-B diodes to test UV detector system at
  multiple intensity levels
• Development of curves of responsiveness for each
  detector circuit
• 3. Testing to determine whether decreased
  temperature will affect reading levels.

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Mission Operations / Data Analysis

• Before launch, StuMURD must be powered on and,
  once the switches are in appropriate positions,
  will begin to gather data. The heat sources must
  be activated and placed in the payload. The
  payload must then be sealed and prepared for
  launch.StuMURD's measurements are
  self-contained and will not need any action or
  input from us on the ground.Following recovery
  of the payload, StuMURD's data, saved in on-board
  memory, will be downloaded to PC using the serial
  cable connection on the Basic Stamp board. Also,
  the HOBO data will be downloaded to PC using its
  serial connection. These sets of data will be
  correlated with the telemetry data to yield all
  applicable analysis and extrapolations.

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Power Consumption
TBD, pending fabrication and testing of systems
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BUDGET
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Schedule / Milestones
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TASK ASSIGNMENTS