PPolySim OS

Sampling & Aliasing

Why do wagon wheels spin backward in films? Sample a signal below the Nyquist rate and a high frequency disguises itself as a low one — the trap of aliasing.

Sampling & AliasingLive

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To capture a signal faithfully you must sample above twice its highest frequency — the Nyquist rate. Sample too slowly and a high frequency masquerades as a lower one: aliasing. Push the signal frequency above half the sample rate and watch the reconstructed wave collapse to a false, slower tone.

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Data Inspector

Nyquist frequency10.0 Hz
Statusproperly sampled
Apparent frequency3.0 Hz

Governing equation

Reading this result: Sampling at 20 Hz puts the Nyquist limit at 10.0 Hz. The 3 Hz signal sits below that, so it is captured faithfully and reconstructs at its true frequency.

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How it works

The Nyquist-Shannon sampling theorem says you must sample above twice a signal's highest frequency to reconstruct it faithfully. Sample too slowly and the reconstructed waveform folds down to a false, lower frequency — aliasing. Push the signal past half the sample rate here to watch the cyan reconstruction collapse. The foundation of all digital audio and imaging.

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Frequently asked questions

Is this sampling aliasing Nyquist tool really free?
Yes. Sampling & Aliasing runs entirely in your browser using your device's own compute, so local use is free forever. You only pay Compute Tokens if you scale a job to the cloud.
Do I need to install anything?
No. Everything runs client-side in a modern browser — no downloads, no license, no account required to start.
Can I save or share my simulation?
Create a free account to save projects, and use a shareable embed or minted DOI to publish a live, interactive version anywhere.
How accurate are the results?
The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.