Evaluate the various freely available geophysical EM inversion software packages for a 'forward' calculation of signal amplitude. Identify a few alternatives and compare their features. If licensed software is required, evaluate the licensed software that you have access to.
The software should be able to perform the following calculation:
- Calculate the voltage induced by one coil in another coil. The source coil has an alternating current or equivalently can be represented as an alternating magnetic dipole moment.
- It is the 'forward' calculation, not the inversion calculation. Most software appears to do both.
- It is the voltage due to a steady AC current in the source. The transient response of the system is less important.
- The coils have variable relative locations in space.
- The source coil may be below the surface, while the sensor coil may be above the surface (there should be no restriction on the placement of the source or sensor in space). Programs that only allow for coils on the ground surface will not be suitable.
- It should be possible to calculate with both horizontal coils and vertical coils.
- Calculate over a broad range of frequencies.
- The ground may be modelled by one or more layers. (A 1D model is sufficient. But 2D or 3D models would be fine too.)
- The model should take into account the ground's magnetic permeability and electrical conductivity.
- The output should be the induced voltage in volts - i.e. not some other unit like apparent resistivity etc.