Sub-Nyquist artifacts and sampling moiré effects, Part 2: Spectral-domain analysis

Sampling moiré effects occur due to aliasing (foldover) when a continuous periodic signal g(x) is sampled using a sampling frequency that does not respect the Nyquist condition. However, visible beating artifacts may also occur when g(x) is sampled using sampling frequencies which fully respect the Nyquist condition. These moiré-like effects, that we call sub-Nyquist artifacts, are more difficult to analyze since they are not visible by our main moiré investigation tool, the Fourier theory. In a recent publication we have addressed this difficulty by bypassing spectral-domain considerations, and studying these phenomena using a signal-domain approach. In the present contribution we go further ahead, and show how, in spite of this difficulty, we can still interpret the phenomena in question from the spectral-domain point of view. This also leads us to new interesting connections between sampling-related phenomena in the discrete world and modulation (beating) phenomena which occur in the purely continuous world, known in acoustics as “beats of mistuned consonances”.