Calculate Size and Decay Channels

Use the Calculate Size and Decay Channels option (Geosoft.uxo.gxnet.dll(Geosoft.GX.UXO.UxaCalculateSizeDecay;Run)*) from the menu AGC Expert User > Static Data Inversion, for each of the sources, to calculate the size (total polarizability magnitude) and decay channels in a source or library database.

Calculate Size and Decay Channels dialog options

Database

Select the database.

Script Parameter: UXANALYZE.SIZE_DECAY_GDB

Gates

Select the Low and Decay gates from the list of available time gates.

  • The default value for the low gate is read from the “UXA_GateFirstValidTime” channel.

  • The default decay gate is determined from the pulse length. If the pulse length is less than 5 ms, the default decay gate is set to the gate closest to 1 ms after current turn-off. If the pulse length exceeds 5 ms, the default decay gate is set to the gate closest to 2 ms after turn-off.

Script Parameters:

  • UXANALYZE.LOGATE
  • UXANALYZE.THRESHOLDGATE

Size channel

Select the target size channel.

Defaults to 'UXA_SIZE'.

Script Parameter: UXANALYZE.TARGETSIZE

Decay channel

Select the target decay channel.

Defaults to 'UXA_DECAY'.

Script Parameter: UXANALYZE.TARGETDECAY

Application Notes

The Size (UXA_SIZE) and Decay (UXA_DECAY) array channels are calculated using:

Where are the primary, secondary, and tertiary polarizabilities, respectively.

  • For both size and decay calculations, if the polarizabilities are not dummy and less than 0.0001, the value 0.0001 will be used instead of the actual value.

    • In addition to the Size and Decay array channels, three additional channels are created:

    • The "low gate value" of the Size channel (UXA_SIZE##, where ## is the low gate value). The Script parameter used to create this channel is: UXANALYZE.TARGETSIZE_SINGLE

    • The "decay gate value" of the Decay channel (UXA_DECAY##, where ## is the decay gate value). The Script parameter used to create this channel is: UXANALYZE.TARGETDECAY_SINGLE

    • The "predicted size" channel (UXA_SIZE_PREDICTED). This channel is based on the low gate value (8, 15) of the Size channel and is categorized as follows:

      UXA_Size
      (default low gate)
      Category
      Approximate Diameter

      Less than 0.5

      		SmallLess than 40mm
      Less than 1.3Medium60 to 80 mm
      1.3 or greaterLargeGreater than 100mm

    Working with Scripts

    When working with scripts with the Calculate Size and Decay Channels dialog, it is recommended that you use the following minimized script files (saved in *.gs format), rather than recording a new script file.

    MetalMapper example:

    SETINI UXANALYZE.SIZE_DECAY_GDB=".\MM_Survey_Source.gdb"

    SETINI UXANALYZE.TARGETSIZE="UXA_SIZE"

    SETINI UXANALYZE.TARGETDECAY="UXA_DECAY"

    SETINI UXANALYZE.LOGATE="8"

    SETINI UXANALYZE.HIGATE="36"

    GX Geosoft.uxo.gxnet.dll(Geosoft.GX.UXO.UxaCalculateSizeDecay;Run)

    TEM2x2 example:

    SETINI UXANALYZE.SIZE_DECAY_GDB=".\\TEM_Survey_Source.gdb"

    SETINI UXANALYZE.TARGETSIZE="UXA_SIZE"

    SETINI UXANALYZE.TARGETDECAY="UXA_DECAY"

    SETINI UXANALYZE.LOGATE="15"

    SETINI UXANALYZE.THRESHOLDGATE="72"

    GX Geosoft.uxo.gxnet.dll(Geosoft.GX.UXO.UxaCalculateSizeDecay;Run)

    *The GX tool will search in the gx folder. The GX.Net tools, however, are embedded within the Geosoft.uxo.gxnet.dll located in the bin directory. If running this tool interactively, bypassing the menu, change the folder to point to the bin directory, then ensure the GX.Net tool is supplied in the correct format when called directly.

    See Also: