https://doi.org/10.1351/goldbook.08297
Sampling less frequently than is required by the Nyquist criterion.
Note:
Undersampling occurs when an analogue signal is digitized with less than two data points per wavelength of the shortest wavelength (highest wavenumber) radiation that reaches the detector.
Undersampling occurs when an analogue signal is digitized with less than two data points per wavelength of the shortest wavelength (highest wavenumber) radiation that reaches the detector.