# What happens on signal during aliasing?

So I have signal with frequency of $15Hz$ and sample rate frequency is $20Hz$.

What happens if we sample the signal at a frequency that is lower that the Nyquist rate? We will have aliasing. Sample rate frequency should be at least bigger than $2*f_{max}$.

I understand that part but I'm confused how that will look like. Can someone help me with that?

• Hi! Um, yes, you probably have some slides and a textbook that say that aliasing will happen. It's very likely that these have illustrations. If you can, read these – it's easier to stay within a given didactic framework than getting to know a new notation for stuff for every question :) basically, it's just a fold-over en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampling_theorem Jan 20 '18 at 13:22
• Here is a sound illustration with aliasing ews.illinois.edu/~serwy/aliasing The assertion "I have signal with frequency of 15Hz" is not quite precise. Is that a mere sine, or the maximum frequency of a signal? Jan 20 '18 at 13:37
• Does this answer answer your question? Jan 20 '18 at 14:38