4.1.4.2. EM Data Manipulation

4.1.4.2.1. Extract data based on times or frequencies

To extract all the data associated with a certain time(s) or frequency(ies), click on the data item of interest and use the menu:

  • TEM data: Data manipulationTime-based extraction of data

  • FEM data: Data manipulationFrequency-based extraction of data

../../../../_images/emDataManMenu.png

NOTE: This will create a new data item.

4.1.4.2.2. View and/or edit the times or frequencies of a data set

To view (with the option to edit) the times or frequencies within a data set, click on the data item of interest and use the menu:

  • TEM data: Data manipulationChange or view times

  • FEM data: Data manipulationChange or view frequencies

../../../../_images/emDataManMenu.png

NOTE: Editing will NOT create a new dataset and will over-write the previous times/frequencies.

4.1.4.2.3. Compute Biot-Savart Primary Field (3D object only)

If the survey geometry has been defined, this functionality computes primary field assuming a current of 1 A using the Biot-Savart law in free-space. The user may choose to compute either the H-field or B-field. This functionality is accessed through:

Data manipulationCalculateCompute Biot-Savart Primary Field

For FEMdata and TEMdata objects, the user must have previously assigned the transmitters. This functionality will compute and create columns for the X, Y and Z components of the magnetic field as well as its magnitude.

For FEM3Dsounding and TEM3Dsounding objects, the user must have previously assigned both transmitters and receivers. In this case, the functionality will compute and create columns for the magnetic field along the receiver direction as well as the magnitude.

4.1.4.2.4. Set Data Normalization (FEM and TEMsounding Only)

Both the EM1DFM and EM1DTM inversion codes can interpret a variety of representations of EM data. To ensure the data are interpreted correctly by the EM1DFM and EM1DTM codes, the data normalization must be properly set. This functionality can be accessed through:

Data manipulationSet Data Normalization

4.1.4.2.4.1. FEM data

For FEM sounding data, the options for defining the type of data are as follows:

  • ppm: secondary field component as parts-per-million of the primary field

  • %: secondary field component as a fractional percent of the strength of the primary field

  • A/m: secondary field component in A/m

  • Total field: total field (primary + secondary) in A/m

4.1.4.2.4.2. TEM data

For TEM sounding data, the options for defining B-field data are as follows:

  • nano-Tesla

  • micro-Tesla

  • milli-Tesla

and the options for defining dB/dt data are as follows:

  • micro-Volts

  • milli-Volts

  • Volts

Note

If the dipole moment of the receiver is 1 Am \(\! ^2\), then the magnitude of the EMF induced in the receiver coil in Volts equals the time-derivative of the magnetic flux density in T/s.

4.1.4.2.5. Set Time Normalization (TEM1Dsounding Only)

The EM1DTM inversion code can use a variety of units for the time channel column. To ensure the data are interpreted correctly by the EM1DTM code, the time normalization must be properly set. This functionality can be accessed through:

Data manipulationSet Time Normalization

The options for defining the units of the time column are as follows:

  • micro-seconds

  • milli-seconds

  • seconds

4.1.4.2.6. Calculate Transmitter-Receiver seperation

This function computes the in-line, cross-line and vertical seperation between the transmitter and receiver for each datum.

4.1.4.2.7. Parse FEM/TEM 3D Sounding by Transmitter

This functionality is available for FEM3Dsounding and TEM3Dsounding data objects. When EM3Dsounding objects contain data at the same location for multiple transmitters (e.g. surface UTEM), the data viewer cannot be opened. This functionality parses the data object into a data object for each transmitter.

This functionality can be accessed through:

Data manipulationCreate new itemParse EM3Dsounding by transmitter

4.1.4.2.8. Merge Parsed FEM/TEM 3D Soundings

This functionality is available for FEM3Dsounding and TEM3Dsounding data objects. This functionality is primarily used for merging multiple EM3Dsounding objects to create a single data object that can be used to construct a mesh. The number of data locations and times/frequencies do not need to be the same. However, the columns in each object must be identical; i.e. number of columns, names, etc…

This functionality can be accessed through:

Data manipulationCreate new itemMerge parsed EM3Dsounding data