Translations:Dictionary:Alias/2/en

(ā’ lē ∂s) 1. Ambiguity resulting from the sampling process. Where there are fewer than two samples per cycle, an input signal at one frequency yields the same sample values as (and hence appears to be) another frequency (the sampling theorem). Half of the frequency of sampling is called the folding frequency or Nyquist frequency, f_N. The frequency f_N + Δf appears to be the smaller frequency, f_N – Δf. The two frequencies, f_N + Δf and f_N – Δf, are aliases of each other.

FIG. A-8. Aliasing of 200 Hz (dashed line) as 50 Hz (solid line). Both 50 and 200 Hz waves give the same sample values when sampled at 250 Hz (4 ms sampling).

See Figure A-8.