Nyquist Spatial Frequency vs Wavelength

To determine the wavelength defaults in Oasis montaj, it is important to remember that if the cutoff entry is less than 1, the value is interpreted as a fraction of the Nyquist frequency, and if the cutoff entry is greater than 1, the value is interpreted as wavelength.

That is:

The Nyquist spatial frequency f = 1/(2*grid spacing). Multiply that by the cutoff fraction (e.g., 0.5), then divide 1 by that number to get the resulting wavelength.

More concisely, cutoff wavelength = (2*grid spacing)/(cutoff fraction)

Example

For a grid spacing of 3000 and a cutoff of 0.5, the Nyquist spatial frequency = 1/(2*grid spacing) or 1/6000 = 0.000167 and the cutoff Wavelength = (2*grid spacing)/(cutoff fraction) or 6,000/.5=12,000