the frequencies 10, 12, 23 and 45 Hz. (a) What is the minimum sampling rate required to avoid aliasing? (b) If you sample at 40 sps, which frequency components will be aliased?

Sampling rate = 90

23 and 45 Hz

Explanation:

The Nyquist criteria states that the sampling frequency must be at least twice of the highest frequency component.

(a) We have 10, 12, 13, 23, and 45 Hz signals

The highest frequency component in this list is 45 Hz

So minimum sampling frequency needed to avoid aliasing would be

Sampling rate = 2*45 = 90 sps

Hence a sampling rate of 90 samples per second would be required to avoid aliasing.

(b) if a sampling rate of 40 sps is used then

40 = 2*f

f = 40/2 = 20 Hz

Hence 23 and 45 Hz components will be aliased.