Automatic DIflux Measurements with AUTODIF by

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Automatic DIflux Measurements with AUTODIFby
Focus on Absolutes

• Jean Rasson, Sébastien van Loo and Nabil Berrami

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Automatic absolute measurements

• Absolute measurements nowadays manually performed
  with the (DIflux Proton Mag) pair. Universally
  adopted method
• Success due to the combination of
• a theodolite (very precise 3D attitude meter)
• a fluxgate magnetometer (sensitive to the
  orientation of the field)
• A robust selfcorrecting measurement protocol(theo
  mech defects coincidence opt/mag axis)
• Task unattended measure of the orientation of
  the geomagnetic vector
• Automate the DIflux measurement protocol

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Hor Axis Enc
VC GUI
Vert Axis Enc
USB
Fluxg/level
8051 µC
C Flash
RS232
Photocells/laser
12 VDC Battery
Power drive
Motor drive
Optical isolation
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AUTODIF Validation target 0.1' 6" 0.0016
accuracy on all angular components
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AUTODIF Measurements in BoulderTarget pointings

• all datas 29.898
• no outliers 29.900

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AUTODIF 2008 Workshop Preliminary Results

• Differences with the BOU baselines (Obs Reference
  AUTODIF)
• D 0.4 0.6 '
• H 3.1 1.7 nT
• Z -1.5 0.8 nT

dH 1 nT -gt ?I -3.6" dZ 1 nT -gt ?I
1.5"

• Possible issues
• Corner cube (azimuth mark) motion (wind?)
• Magnetism of electronics console
• Slight diurnal baseline variation

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Future improvementson AUTODIF

• Improve software for motor drives (reliability,
  longevity)
• Remove cable stress on alidade (accuracy)
• Lower noise in laser and fluxgate electronics
  (accuracy, resolution, reliability)
• Implement sheduled measurement sessions
  (operation)
• Package device for robust and userfriendly
  operation and transport (dissemination operation)

Thanks for your attention