Cosine Roll-off Bandpass (COSNB)

Use the Cosine Roll-off Bandpass option to apply a cosine roll-off bandpass filter.

Cosine Roll-off Bandpass Filter dialog options

Long wavelength cutoff	Long Wavelength central cutoff, in ground units.
Short wavelength cutoff	Short Wavelength central cutoff, in ground units.
Degree of cosine function	Degree of sharpness of the filter operator (default = 2).

Application Notes

The Cosine bandpass filter allows to pass the desired mid- range wavelengths while attenuating the low and high extremes of the wavenumber continuum. The Filter Order controls the degree of the sharpness at the two cutoffs. The higher the number the closer the shape of the operator is to the ideal bandpass operator. However one is cautioned not to apply the ideal bandpass filter as it manifests a ringing artefact. A common alternative is the Cosine roll-off filter (COSN).

Cosine Bandpass Filter

Where:

k0	Low wavenumber cutoff in cycles/ ground unit.
k1	High wavenumber cutoff in cycles/ground unit.
inc	wavenumber width max(3,n/10).
n	Number of data points 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.