Frequency of a single sample in a digital signal and aliasing

1. What is the relationship between frequency and aliasing?
2. How is sampling rate and aliasing related?
3. What is the relation between sampling frequency and signal frequency to avoid aliasing effect?
4. How do you find aliasing frequency?

What is the relationship between frequency and aliasing?

Aliasing is the effect of new frequencies appearing in the sampled signal after reconstruction, that were not present in the original signal. It is caused by too low sample rate for sampling a particular signal or too high frequencies present in the signal for a particular sample rate.

How is sampling rate and aliasing related?

When the sampling rate is not large enough (not larger than 2B Hz), then interference among adjacent bands will occur, and this results in the phenomenon of aliasing. In this case, the original signal cannot be recovered from the sampled signal.

What is the relation between sampling frequency and signal frequency to avoid aliasing effect?

According to the Shannon Sampling Theorem, use a sampling frequency at least twice the maximum frequency component in the sampled signal to avoid aliasing.

How do you find aliasing frequency?

where f_N is the folding frequency, f_s is the signal frequency, and m is an integer such that f_a < f_N. For example, suppose that f_s = 65 Hz, f_N = 62.5 Hz, which corresponds to 8-ms sampling rate. The alias frequency then is f_a = |2 × 62.5 − 65| = 60 Hz.