Tracking board design for the SHAGARE stratospheric balloon project Supervisor : René Beuchat Student : Joël Vallone
Motivation Send & track a gamma-ray sensor in the stratosphere with a meteorological balloon Extreme conditions: 30 Km altitude -60 C 0.001 atm 3 m free-fall when landing Weather balloon Payload : Gamma-rays sensor Tracker board : radio, GPS, SD card, controller, sensors Lithium-ion battery Thermal isolation parachute payload GPS + radio 2
Outline Project context Partners & task allocation Tracking board overview Hardware PCB Software Gamma-rays sensor Expectations VS reality First flight Conclusion 3
Project context HAGARE - High Altitude Gamma Rays Experiment Balloon mission launched with the ESA Monitor gamma-rays in the stratosphere Small HAGARE prototyping for HAGARE Tracking board Experimentation of the gamma-rays sensor Test flight with a stratospheric balloon 4
Partners Processor architecture Laboratory High Energy Physics Laboratory Controller & software design Gamma ray sensor design Technical support & Project follow-up 5
Final task allocation LAP Ma. student : Joël VALLONE LPHE Ma. student : Olivier GIRARD Tracker board design Components choice PCB layout μcontroller software Gamma-ray sensor design Sensor fine-tuning miniaturization Interface with tracker board Joined testing and interface definition + SHAGARE : First flight 6
Tracking board - specifications The tracker board must : Work under extreme conditions: -60 C, 0.001 atm Only industrial class hardware Testing under artificial conditions Handle ray events from the Gamma-ray sensor : 10 Hz max Sample data from the housekeeping components Temperature, battery voltage, pressure, GPS 1 Hz Magnetometer 5 Hz Store locally & transmit the data to the ground 2GB industrial SD-card 1.2 Kbps VHF 144.8 MHz amateur radio transmission 7
Tracking board - hardware Blue = tracker board DC/DC & LDO 7.2V battery 3.3V GPS 3.3V Enable {0,1, } UART An.0 3.3V Voltage monitor Radio transmitter FSK - 144.8 Mhz 5V An.{1,2} μ Controller + JTAG TX Enable I 2 C SPI An.3 An.4 Trigger Ack 3.3V 5V Temperature Temperature Magnetometer Pressure 3.3V SD card Gamma-ray sensor SPOT 2GBytes, FAT32 Battery system Autonomous web live GPS 8
Tracking board - PCB 4 layers PCB: 2 digital signal planes 1 analog signal plane 1 ground plane Plane fill with : 7.2V power 5 V power Board size: 10x16 cm Intentionally large Extension ease Stacking on gamma-rays sensor 9
Tracking board software(1/2) Before lift-off: Initialize & test Flight loop: Sampling 1Hz and 5Hz Store Transmit if enough battery RESET Power save mode N Initialize Self test OK? Y Flight Loop Landed: Radio heartbeats Power save mode Y Has landed? N 10
Tracking board software(2/2) Enforce an operating policy according to mission and system status. Use of operating modes: Flight: Sample, store locally and radio transmit sensing data Enabled modules: All Power: 670 mw => 24 hours autonomy Safe: Only sample sensing data and store locally Enabled modules: Controller, sensors, SD-card Power: 210 mw Power Save : Transmit the last position with radio heartbeats Enabled modules: Controller and Radio Power: 150 mw 11
Gamma-rays sensor- prototype Trigger logic Crystal + Photo-diode + Temperature sensor Dataloger: Arduino + SD card Battery system 12
Gamma-rays sensor- interface Vray threshold -> trigger -> lock -> sample Handshake by software Time Vray: gamma-ray energy level Trigger: event detection Lock: freeze the sensor sample 13
Tracking board: Expectation VS reality Expectations: 1. Analysis 2. PCB design 3. PCB testing 4. Software programing 5. Stratospheric testing 6. First flight with this tracking board Reality: 1. Analysis 2. PCB design 3. Partial PCB testing 4. Partial Software prog. 5. First flight without this tracking board use of Arduino 14
Implementation status PCB prototype designed and available Software and PCB verifications status: Component Coded PCB Verified Controller + JTAG - OK Main execution flow OK OK GPS + Comm. UART OK OK Housekeeping - ADC OK X Gamma events OK X Magnetometer + Comm. I2C X X SD-card + Comm. SPI X X Radio transmitter X X 15
First flight payload setup Meteosuisse payload Housekeeping sensors Temperature ext. Pressure Humidity GPS Periodic radio transmission 400Mhz, AFSK, 2200 bauds 600 g SHAGARE payload Housekeeping sensor: Temperature int. Gamma-rays sensor Local storage only 2GB SD-card 1200 g 16
First flight the story Launch: Payerne the 30.06.2013 at 12:30 Landing: Sainte-Croix the same day at 15:00 17
First flight discussion(1/4) Accurate trajectory predictions when the correct burst altitude and ascension speed are given. 18
First flight discussion (2/4) Altitude [km] 30 20 10 Temperature [ C] 20 0-20 -40 Inside Outside 0 50 100 150 Ascension and fall speed are comparable: 6 m/s 32 km burst altitude The polystyrene isolation and the electronics heating limit the temperature drop inside the payload. -60 C outside VS -6 C inside -60 Time [min.] 0 50 100 150 19
First flight discussion (3/4) Temperature and pressure profiles available for testing Fast decrease in time and altitude then stabilization 1000 20 Pressure - hpa 800 600 400 200 0 0 10000 20000 30000 Altitude - meters Temperature - C 0-20 -40-60 0 10000 20000 30000 Altitude - meters Application: simulate the balloon flight conditions The Space Center has a testing chamber for pressure and temperature reproduction. 20
Gamma-rays - THE mission histogram The gamma-rays events rate was lower than 3 Hz Electronics noise below 500 kev Histogram: aggregation of gamma events Events count # of event on same energy level 100 Energy spectrum 60 20 Electronics noise 1000 1500 Energy [kev] 21
Conclusion The SHAGARE mission is accomplished: Gathered data and experience for the HAGARE mission The stratospheric tracking board hardware platform is available in the LAP: The LPHE is interested : wants to order 9 tracking boards. Hardware: Fully designed Circuit Partially assembled and tested Software Main control loop coded Several modules implemented : GPS, ADC sampling, UART and gamma-rays events. 22
Further work HAGARE: Large scale gamma-rays detector Ethernet N*100 FPGA Data filtering USB Embedded computer Sensors 100 sensors, FPGA processing, embedded computer Tracking board: stratospheric balloon experiments finish the software finish the tests on the manufactured PCB 23
Questions?? http://wiki.epfl.ch/shagare 24
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Gamma-rays - signal noise histogram 26
Gamma-rays - flight histogram 27