Electromagnetics: Description of Modules
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EM processing makes use of the SimPEG library.

TDEM 1D Inversion
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TDEM inversion makes use of the SimPEG library (see references below). The inversion is 1D, so it requires as input a single measurement. Line data is imported using the Import Line Data tool in the Vector menu.

Options are as follows:

* Line Number
* Fid/Station Name
* Bird Height – height of sensor.
* Data channel prefix – prefix in ASCII data file, indicating a data channel.
* Waveform Type – an option to select the waveform for a list of standard types.  This can be VTEM Waveform, Ramp Off Waveform, Trapezoid Waveform, Quarter Sine Ramp On Waveform, Triangular Waveform and HalfSineWaveform.
* Tx Peak time – time when the input VTEM waveform is at its maximum.
* Tx Ramp Off start time
* Tx Off Time – time when the waveform is completely off.
* Source Type – can be Circular Loop or  Mag Dipole.
* Tx Orientation – transmitter orientation, can be x, y or z.
* Tx Area  – transmitter area (only for circular loop source)
* Number of turns in loop (only for circular loop source)
* Current in loop (only for circular loop source)
* Permeability of the background
* Rx Orientation – receiver orientation, can be x, y or z.
* Mesh cell size
* Mesh number cells in x direction
* Mesh number cells in z direction
* Mesh number of cells to pad
* Pad cell multiplier
* Conductivity Air
* Conductivity Halfspace
* Data Relative Error (%)
* Data Noise Floor
* Optimization - maximum iterations
* Load window times – text file with the window times.

.. image:: _images/eminv.png