PPolySim OS

Eye Diagram

See digital signal integrity the way engineers do. Overlay thousands of received symbol traces into the classic eye — and watch ISI, noise, and jitter close it.

Eye Diagram StudioLive

Controls

Overlay many received traces aligned to the symbol clock. A wide-open eye = easy detection; ISI, noise, and jitter close it.

Presets

▶ Run in Python

Data Inspector

Pulse shaperaised-cosine
Eye height1.67 / 2
Eye width52% of T
SNR margin24.4 dB
Roll-off β0.35

Raised-cosine spectrum

Nyquist ISI-free criterion

Reading this result: A wide-open eye means easy, low-error detection — the +1 and −1 levels are cleanly separated at the sampling instant. Here the eye height is 1.67 (of a possible 2) and the eye width is 52% of the symbol period. ISI, noise, and timing jitter all close the eye; raised-cosine shaping trades bandwidth (larger β) for less ISI, and a higher β widens the eye.

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How it works

An eye diagram overlays many two-symbol windows of a received waveform, aligned to the symbol clock. A random 2-PAM/NRZ bit stream is pulse-shaped — rectangular NRZ or a raised-cosine pulse with adjustable roll-off β — then passes through a bandlimited channel with additive noise and optional timing jitter. The vertical opening at the ideal sampling instant is the eye height (margin against noise); the horizontal opening is the eye width (margin against timing error). Raised-cosine shaping satisfies the Nyquist zero-intersymbol-interference condition p(kT)=δ[k]: raising β trades occupied bandwidth for a wider, more forgiving eye, while noise and jitter squeeze it shut.

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Frequently asked questions

Is this eye diagram ISI pulse shaping tool really free?
Yes. Eye Diagram 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.