Student Made Ultraviolet Radiation Detector Presented for your approval by: THE LATE BALLOONERS StuMURD.

Student Made Ultraviolet Radiation Detector

Presented for your approval by:

THE LATE BALLOONERS

StuMURD

Through StuMURD, The Late Ballooners will attempt to approximate the maximum level of UV-B radiation incident on the earth before

being filtered by Earth’s ozone layer and

other destructive forces.

StuMURD has 4 main systems:

1. UV Detector System

2. Internal Temperature Detector System

3. Thermal System

4. Mechanical System

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

Architectural Diagram of UV Detector System

BASIC STAMP

ADC (8-bit)

Photo detector 1 Photo detector 4

Photo detector 3Photo detector 2

Op Amp

Op Amp Op Amp

Op Amp

EEPROMmemory

Power

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

UV Detector System – Data Acquisition Subsystem part 1

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

R1

R2

R3

C1C2

SENSOR

_

+

+

_

Non - InvertingAmplifier to

amplify signalagain

V+

V+

AmplifiyCurrent fromSensor to a

voltage.

CH14

CH25

6CH3

7DGND

SARS

DO

Vref

AGND

11

10

9

8

CH03

CLK12

CS2

DI13

V+1

Vcc14

AMP

AMP

4 Channel ADC0 to + 5 Volts

8 Bit Resoluton

V+

TOBASICSTAMP

+5V VrefChip

SINGLE SUPPLYOPAMPS

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

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.

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.

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.

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.

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.

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 –20C . Our main component to keep the payload’s 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 54°C. 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 54°C (130 °F.)

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

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.

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.

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 balloon’s orientation to the sun.

Software Implementation• (before running main program, all memory locations have been set to zero)

• MAIN:

• go to Boot_up subroutinebegin 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

• return

Collect_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

•  

• Download Data:

• Cycle through all data positions in EEPROM and read them to an external file or debug

• Window

• end

A detailed plan for calibrations is TBD but will involve:

1. Use of UV-B diodes to test UV detector system at multiple intensity levels

2. Development of curves of responsiveness for each detector circuit

3. Testing to determine whether decreased temperature will affect reading levels.

FABRICATION AND TESTING –

Calibrations

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.

WEIGHT BREAKDOWN

Item Mass (g)

Box 125

4 UV detectors 15

HOBO 29

Batteries 182

Additional Board w/components 75

Heater 60

Main Board (Basic Stamp) 43

Total 529

Power Consumption

TBD, pending fabrication and testing of systems

BUDGET

Item Part # Retailer Qty Each

OPAMP MCP601 - PDIP single supply op amps 8 $0.07ADC ADC0834BCN 1 $3.85Vref LM 336bz- 5.0 1 $1.71Caps .01 micro probably can find caps and resistors or buy at radio shack handfull

.1 micro handfullResistors 10 Meg Ohm 4Perf Board min of 4 x 8 inches Radio shack or find in physics building 1 to startWireSwitches ct2066 . 1 $1.09DIP sockets handfullUV Detectors JEC 0,3S lasercomponentsusa.com 4 $66.00HOBO H08-002-01 Onset 1 $65.00Battery TBDDiodes for Testing TBD, similar tolerance to the photodiodes in order for testingBasic Circuitry various minor parts TBD

Cost

$0.56$3.85$1.71

$1.09

$264.00$65.00

Total Cost$336.21

Schedule / Milestones

TaskMS - PDR approvalMS - CDR approvalMS - StuMURD testing hardware completeMS - StuMURD hardward completeMS - StuMURD calibration and testing completeMS - FRR approvalMS - StuMURD flight

TASK ASSIGNMENTS

ProjectManagement

Lane Johnson

Data AnalysisL. Johnson

ACES Panel

Team LeaderL. Johnson

PayloadDesign

M. Landry

MechanicalA. Verette

ThermalA. Verette

SoftwareL. Johnson

SystemD. Rodriguez-hart

ElectricalD. Rodriguez-hart

AccountingA. Verette

Work LoadL. Johnson

TimelineL. Johnson

DataAcquisitionD. Rodriguez-hart

Comparisonswhole team

Summarywhole team

ResultsL. Johnson