Hi Daniel Lalich,
Answer to your question "how to label time axis?"
Secondly, it is my understanding that you want to calculate sampling frequency.
According to Nyquist sampling theorem ,
- For a base band signal fs (sampling frequency) should be greater than the fmax(maximimum frequency ). Therefore the minimum sampling frequency is 2*fmax.
- On the other hand for band pass signals, the minimum sampling frequency is different .
Let f_H and f_L be the highest and lowest frequencies respectively in the band pass signal
where k= floor(f_H/(f_H-f_L))
There are many other possible sampling frequencies for band pass signals. You may have to understand Nyquist Band pass sampling theorem to know more.
To conclude, you need prior knowledge of sampling frequency to get the exact time axis labels. On the other hand , you can also use minimum sampling frequency.