Processing

Fugro Airborne Surveys uses spectral component analysis or Spectra Plus^TM to reduce statistical noise in airborne gamma-ray spectrometer survey data. These techniques utilise the complete 256 or 512 channel spectrum and are considerable advances in the radiometric data processing technique. The results are a more accurate measure of radioelement ground concentration, which improves considerably the discrimination between different geologic units with similar radioelement concentrations. This processing also results in improved discrimination of man-made radioactive sources from background.

Fugro ternary presentation of the eU, eTh, K concentrations, Anti Atlas Region of Morocco.Data courtesy of the Ministry of Energy and Mines, Morocco.

Spectra Plus processing of the PGAM-1000 data also offers energy re-calibration on the individual spectra from each crystal.

We have considerable experience dealing with radiometric data measured in rugged terrain. Careful evaluation of the deviation from the assumed exponential altitude attenuation plus improved micro-leveling techniques has permitted us to extract useful radiometric maps at ground clearances that would otherwise render radiometric data useless.

Gridding airborne gamma-ray data presents certain challenges because of the inherent statistical fluctuations in the data. Either the data must be smoothed and interpolated, or an average surface must be generated. Fugro Airborne Surveys offers a radiometric gridding method that follows the Geological Survey of Canada approach and computes an average surface using an inverse distance weighting function. This process yields a smoothed and interpolated grid in one step.

Fugro Airborne Surveys has experience in reprocessing of older existing radiometric datasets, which may be recovered from magnetic tape archives or digitised from analog records. These data are then "back calibrated" to convert values to ground concentrations, enhanced, and image processed to provide additional information for the interpreter.

Products normally delivered for airborne gamma-ray spectrometer surveys include colour or contoured parameter maps reflecting the radioelements of interest, ratio maps, ternary maps and full spectrum and windowed digital data on a variety of media and formats.