Bandpass (BPAS)

Use the Bandpass option to apply a bandpass filter.

Bandpass Filter dialog options

Long wavelength cutoff	The long wavelength cutoff in ground units. As shown in the illustration, this parameter corresponds to k0-1.
Short wavelength cutoff	The short wavelength cutoff in ground units. As shown in the illustration, this parameter is equivalent to k1-1.
Pass Reject	Choose whether to pass or reject the defined band. The default setting is Pass.

Application Notes

The bandpass filter (BPAS) can be used to pass or reject a selected range of wavelengths within the data. However, applying a simple cutoff filter to an energy spectrum almost invariably introduces a significant amount of oscillation (Gibbs’ Phenomenon). This filter is included for completeness, but we recommend using a tapered filter such as the Butterworth filter (BTWR).

Bandpass Filter

Where:

k0	Low wavenumber cutoff (cycles per ground unit).
k1	High wavenumber cutoff (cycles per ground unit).

Wavenumber Domain Variable Definitions

The following variables are used in the wavenumber domain:
k	Wavenumber increment, used to depict a radially symmetrical variable.	Where: np: number of points cs: cell size
μ	X-component of the wavenumber.
v	Y-component of the wavenumber.
r	Radial component of the wavenumber.
θ	Angular (polar) component of the wavenumber.

Ground unit refers to the survey ground units defined in your grid (e.g., metres or feet). Ground units may also be left unspecified.