Howtosignalprocessing
- What is frequency domain aliasing?
- How do you find aliasing frequency?
- How do you avoid aliasing effect in a sampled signal?
- What is the formula for folding frequency?
What is frequency domain 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 do you find aliasing frequency?
where fN is the folding frequency, fs is the signal frequency, and m is an integer such that fa < fN. For example, suppose that fs = 65 Hz, fN = 62.5 Hz, which corresponds to 8-ms sampling rate. The alias frequency then is fa = |2 × 62.5 − 65| = 60 Hz.
How do you avoid aliasing effect in a sampled signal?
The solution to prevent aliasing is to band limit the input signals—limiting all input signal components below one half of the analog to digital converter's (ADC's) sampling frequency. Band limiting is accomplished by using analog low-pass filters that are called anti-aliasing filters.
What is the formula for folding frequency?
(Also called Nyquist frequency.) The highest frequency that can be measured using discretely sampled data. It is given by nf (rad s-1) = π/Δt, where nf is the Nyquist frequency and t is the time increment between observations.
