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STORM

Stratospheric Observations and Radiation Monitoring

comments welcome: mrongen@halifax.rwth-aachen.de

Summary

  • Still under development (T.B.D. = “to be done” or “to be determined”), no flight experience yet,…
  • 4 AA Batteries, Latex Balloon
  • 434.xxx Mhz, Shift xxx, xxx Baud
  • Transmission every xx seconds

Payload

  • Five main modules clustered around central battery pack
  • (mainly) I2C as communication protocol between modules

Power Distribution Board (PDB)

  • Distributes 6V from 4 AA batteries to all modules
  • Mounted to back of standart battery pack
  • Monitors battery voltage and total current via INA219 IC and 200mOhm shunt resistor
  • Design Files: (Link)

Batteries

Flight Controle Unit (FCU)

MicroController and GPS

Inertial measurement unit (IMU) and Telemetrie Module

  • Integrated buck-converter power supply to 3.3V for itself and the uC
  • Design Files: (Link)
IMU
Telemetrie
Storage
  • not all data can be transmitted, but everything is stored for offline analyses
  • 1 GB micro SD-Card interfaced via SPI

Sensor Fusion Board (SFB)

  • distributes I2C to OTP, RD and PDB modules
  • UART to GSM module
  • +3V3 to OTP and PDB
  • Design files: (Link)

Data packet structure and integration into the HabHub

T.B.D.

Outside Temperature Probe (OTP)

GSM-Module

Radiation detector (RD)

Theory

for more information see for example: “Ionizing Radiation in Earth’s Atmosphere and in Space Near Earth / DOT/FAA/AM-11/9”

At earths surface about half of the natural ionising radiation originates from radioactive isotopes in the ground. The other half is a result of charged particles hitting the earths atmosphere (so called cosmic rays). As cosmics rays interact with nuclei in the atmosphere extensive air showers with hunderts of secondary particles are created (search for Heitler model to get a rough idea), which subsequently decay as they propagate towards the surface. Going up in the atmosphere the dose rate increases, as more and more secondary particles are present. At a height of around 20 kms, at the so called Pfotzer maximum, the combined dose rate of primary and secondary particles reaches its maximum. Above that height the amount of ionising radiation decreases again.

Detection Options

  • PMT (Photomultipler) with Scintillator:
    • + high sensitivity
    • + good energy resolution
    • - high voltage needed (~ 1kV)
    • - heavy
    • - suscaptible to temperature and magnetic field changes
    • - complex to setup
  • SIPM (Silicon photomultiplier) with Scintillator
    • + high sensitivity
    • + good energy resolution
    • + lightweight
    • - high voltage needed (~80V)
    • - VERY sucaptible to temperature changes
    • - complex to setup
  • Geiger Müller tube
    • + easy to setup
    • + lightweight
    • o average sensitivity
    • - high voltage needed (~500V)
    • - no energy information at all
  • Solid state detector (Teviso RD3024)
    • + trivial to setup
    • + low voltage (~5V)
    • + “some” energy resolution through the pulse with
    • + lightweight
    • - low sensitivity
    • - EMI sensitive

Teviso RD3024 Module

  • array of radiation soft PIN diodes
  • integrated bias-, amplification-, comperator-, and output-shaping circuit
  • ~6CPM/uSh/h, essentially stable from 3 - 6 V, -40 - 60 °C
  • pulse width is supposed to be slightly correlated to particle energy (to be tested further)
  • SMD package
  • Teviso sponsored one unit, otherwise ~120€

Breadboard test

  • ATTiny85 triggers on rising and falling edges of RD3024 TTL pulse
    • pulse width resolution: 1us
    • accuracy test with 130 us function generator pulses: 130.2 +- 2.3 us digitised
  • ATTiny acts as I2C slave against FCU

Flight module

  • Integrates buck-converter power supply to 3.3V
  • allows soldering a grounded aluminium EMI shield over the RD3024
  • Design Files: (Link)

Camera

  • FlyCamOne Eco V2
  • integrated power supply
  • Video, Timed Pictures
  • 720 x 480px @ 30 fps
  • max. 8 GB Micro SD card
  • 4-6 V input

Conformal coating

  • breakdown voltage of air is drastically reduced at low pressures (Paschen Law)
  • can lead to elevated discharge rates even at voltages below sparking
  • coat PCBs and plugged connectors with Plastik70

Environmental testing

Vaccum

  • T.B.D.: Test full electronics system with conformal coating for elevated discharge at Paschen minimum.

Temperature

  • T.B.D.: Battery temperature is not supposed to drop below -10°C when exposing powered payload to -50°C for 20 minutes

EMI

  • T.B.D.: Test GPS reception and RD noise during 70cm and GSM transmissions

Telemetries range

  • Possibly a test chasing a commercial hot air ballon with the payload on board

Boyancy

  • Should stay afloat on standing water for at least 10 minutes

Mechanical integration and isolation

T.B.D.

Balloon and Parachute

  • Balloon: Totex TA-1000
  • Parachute: Spherachute Balloon Parachute - 54in

both from www.randomengineering.co.uk

Radar reflector

300 mm wide, build from Balsa wood, coated with aluminium tape weighs in at around 250g, so a little on the heavy side

Chase car

  • Diamond MR-77S Mag Antenna
  • Custom QFH antenna - T.B.D.

Red Tape

  • in Germany I need a Flugverkehrskontrollfreigabe (liftoff permission) from the Deutsche Flugsicherung (German airspace control)
  • 2 weeks lead time
  • this includes the need for a 1 day aviation insurance (~60€))
projects/storm.txt · Last modified: 2015/03/10 20:45 by storm