Apparent Density Calculation Filter

Use the Apparent Density Calculation option to apply a Fast-Fourier Transform Apparent Density filter to a channel.

The filter option is available with the following extensions and menus:

• Geophysics: 1D FFT > 1D Filtering
• Gravity and Terrain Correction: Moving Platform Gravity  > Apply Single FFT Filter

Apparent Density Calculation filter option

Depth to the top of model	Depth to the top of the model. Default = 1 Script Parameter: FFTDENS.DEPTH
Thickness of earth model	Thickness of earth model. Default = 1 Script Parameter: FFTDENS.THICK
Low-pass cutoff (in ground units)	Low-pass Butterworth filter cutoff wavelength. Default = 1 Script Parameter: FFTDENS.LP
Background Density (g/cm3)	Background density (g/cm3). Default = 0 Script Parameter: FFTDENS.DENS

Application Notes

In order to have correct density units, the input data fiducial base must be in metres. The low-pass filter can be used to remove noise in the data that would be amplified by the downward continuation. A low-pass cutoff of 1 to 1.5 times the depth is normally appropriate.

Apparent Density Filter

Parameters:

t Thickness, in ground_units, of the earth model.
d Background density in g/cm³
G Gravitational constant.