Butterworth Notch (BTWRN)

Use the Butterworth Notch option to apply a butterworth notch filter.

Butterworth Notch Filter dialog options

Wavelength cutoff	Central Wavelength to reject, in ground units.
Filter order	Degree n of the sharpness of the filter operator (default = 8.0).

Application Notes

The Butterworth Notch filter allows to reject the desired mid-wavenumber range while maintaining the low and high extremes of the wavenumber continuum. The Filter Order controls the degree of the sharpness of the cutoff wavenumbers.

Butterworth Notch Filter

Where:

kc	Wavenumber cutoff in cycles/ ground unit.
n	Positive integer value determining the degree of sharpness of the cutoff.

Wavenumber domain variable definition

k	Wavenumber domain increment, used to depict a radially symmetrical variable.	where: np is the number of points cs is the cell size
u	X component in the wavenumber domain.	k = 2π ( i μ+j ν )
v	Y component in the wavenumber domain.
r	Radial component in the wavenumber domain.	also 2πk
θ	Polar component in the wavenumber domain.

Ground_unit is the survey ground units as defined in your grid (e.g. metre or feet). Ground units may be left undefined.