Enter your Sampling Frequency (fs) and Signal Frequency (fin) to find the Nyquist Frequency, Aliased Frequency, and Nyquist Zone — plus an Aliasing Status flag so you know if your signal is folding back into the baseband. Set the Maximum Analysis Frequency and Maximum Harmonic Order to track how harmonics alias across your ADC's spectrum.
Nyquist Frequency
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Aliased Frequency
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Nyquist Zone
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Aliasing Status
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ADC aliasing occurs when the sampling frequency is insufficient to accurately represent high-frequency signal components. According to the Nyquist theorem, the sampling rate must be at least twice the highest frequency component to avoid aliasing.
The Nyquist frequency is calculated as half the sampling frequency (fNyq = fs/2). It represents the highest frequency that can be accurately sampled without aliasing.
Nyquist zones are frequency bands of width equal to the Nyquist frequency. Signals in odd-numbered zones (1st, 3rd, 5th) alias normally, while signals in even-numbered zones (2nd, 4th, 6th) alias with frequency inversion.
Even if the fundamental frequency is below the Nyquist limit, its harmonics may exceed it and fold back into the frequency band of interest, creating spurious signals that can interfere with the desired signal.
Oversampling occurs when fs > 2 × signal frequency, providing good signal reproduction. Undersampling occurs when fs < 2 × signal frequency, deliberately used in some applications but requiring careful alias management.
Use anti-aliasing filters to remove frequency components above the Nyquist frequency before sampling, increase the sampling rate, or design the system to tolerate controlled aliasing in undersampling applications.
When a high-frequency signal or harmonic aliases into the first Nyquist zone (0 to fNyq), it appears as a lower-frequency spurious signal that can interfere with your desired signal band.