The EM Utilities extension provides a set of tools to inspect, filter and prepare your time domain electromagnetic (TDEM) data before performing a TDEM inversion using VOXI Earth Modelling. With EM Utilities, you can view TDEM arrays, perform Tau calculations, filtering and noise elimination.

Show selected EM array channel profiles

EM decays are recorded in upwards of 30 time gates. Showing the data of all gates at once can overwhelm the database profile pane and obstruct the data inspection This feature enables you to display a subset of gates of an EM array channel, allowing you to focus on a specific gate or set of gates of particular interest, for example you can inspect only the late times when investigating a deeper geophysical feature.

Calculate and remove EM array noise

Clean your electromagnetic (EM) dataset before performing an inversion by filtering out noise from your EM data. You can calculate the noise for each time gate of the EM decay array and optionally remove gate values outside the noise envelope.


The EM Utilities extension for Oasis montaj provides essential tools for inspecting TDEM arrays, performing Tau calculations, filtering and removing noise.

EM Tau calculation

The rate of decay of transient EM data is an indicator of conductance. To discriminate conductors from overburden, we look at the rate of decay of the transient EM data, Tau. Given and EM array you can calculate an array of Tau values. Gridded Tau values are useful for visualizing and interpreting the subsurface conductivity.

View coincident EM arrays

View coincident arrays along with their error envelopes. This is an excellent tool for inspecting EM array data in order to identify noise prior to the inversion process. You can also use it after the inversion to compare the observed data with the predicted results.

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