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.