ABEM Terrameter LS advanced pre-processing

This tool is for processing of data from ABEM Terrameter LS instruments only. The tool currently performs the following tasks:

  • Estimation and removal of harmonic (powerline) background noise
  • Spike removal
  • Drift removal with exponential drift model
  • Gating of recorded IP decays with gaussian window shape

The implemented signal processing workflow is described in the following publication: Olsson, P.-I., G. Fiandaca, J. J. Larsen, T. Dahlin, and E. Auken, 2016, Doubling the spectrum of time-domain induced polarization by harmonic de-noising, drift correction, spike removal, tapered gating, and data uncertainty estimation, Geophysical Journal International. pdf

Using the tool

To use the tool you need access to the project folder containing the project database (usually named project.db) as well as the raw measured files from the instrument (normally located in a subfolder named Rawdata). To import data using the tool go through the following steps

  • Select the “ABEM Terrameter LS advanced pre-processing” import type
  • Select “Add Abem Terrameter Database (.db) File” and select the project database
  • After selecting the database select which task from the project to process using the Task ID dropdown, serveral tasks from the same database can be processed at the same time by selecting the database several times with different task ID’s
  • If you want to locate the imported data at their correct geographical location select the “Add Elec Pos (.ewp) File” option to and an .ewp file (see the .dat file import guide for a description of the format), remember to also select a coordinate system
  • Select “Run”, when the log shows “All processing are done and data imported to workspace, you can now close this window.” The data have been imported to the workspace and the window can be closed.

Additional settings

  • Estimated frequency: the estimated frequency of the local powerline noise, it is possible to add a second frequency to account for things such as electric railways
  • Gates per decade: IP gates per decade after re-gating the IP decay
  • First gate: center time of the first IP gate
  • Number of processors: Number of CPU’s used for the signal processing