Drag blocks. Watch signals. All in the browser.

Try it live or see it in a textbook

LIVEqpsk_demo

Bit SourceSRC

modQPSK

RRC FilterDSP

β · roll-off0.35

AWGN ChannelCHN

ConstellationSINK

EVM7.9%

01 · WHAT IT DOES

Build it, run it, learn from it.

One canvas takes you from a blank graph to a running instrument you can share — the same engine that powers the editor and every embed.

BUILD

Wire the whole chain

Drag PRBS, FIR, mixers, channel models, CFAR and beamformers onto the canvas and connect them into a graph. Every block exposes its real parameters.

SIMULATE

It runs as you tune

Your graph compiles to a WebAssembly worker and runs live. Scopes, spectra, constellations, MSO, range-Doppler, range-angle and polar PPI update in real time.

LEARN

Read, fork, embed

Start from curated read-only labs, fork them, and rewire. Drop any lab into a lesson or post as an embed — the reader turns a knob and the math responds.

02 · FEATURED DEMOS

Built for the whole signal chain.

Worked examples ship with the editor — fork, retune, rewire. Every demo is one URL away from a runnable lab.

3 live · 3 coming soon
new sim every two weeks

RADAR

Range-Doppler GPU tracker

pulsed LFM · 64 pulses · 2 targets

src → mixer → mf → fft²

COMMS

BPSK in noise

awgn channel · live constellation · EVM

src → mod → awgn → sink

TIMING

Sampler & timing recovery

symbol clock · sample instants on the eye

src → sampler → ted → loop

SPECTRUM

COMING SOON

Windowed FFT

hann · 4k bins · two-tone test

src → window → fft in progress

OFDM

COMING SOON

OFDM subcarriers

64-FFT · 4 pilots · DC null

bits → qam → ifft → cp in progress

CONTROL

COMING SOON

PID step response

Kp=2 · Ki=0.6 · Kd=0.18 · 18% OS

ref → pid → plant in progress

03 · EMBED

Drop a live lab into any page.

One line of markup turns any course note, textbook or blog post into an interactive station. The reader tunes a knob — the math responds.

Chapter 16 · Pulse Shaping & Inter-symbol Interference

16.4 The root-raised-cosine filter

A practical communications receiver must reject out-of-band noise without smearing energy across symbol boundaries. The root-raised-cosine pulse splits the matched-filter response symmetrically between transmitter and receiver, so the cascade satisfies the Nyquist no-ISI condition at the symbol instants.

h_RRC(t) = (1 / √T_s) · ƒ(t, β) (16.7)

The roll-off factor β trades excess bandwidth for time-domain sidelobe suppression. Try sweeping β below and observe the constellation tighten: at β → 0 the pulse approaches a sinc and the spectrum is brick-wall, but the time-domain ringing pays the price elsewhere in the chain.

POTIK QPSK RRC Overview v1 embed.potik.org/bpsk-noise

Fig. 16-4 · Live: QPSK source through AWGN with constellation readout. Resample by reload.

Choosing β = 0.35 is a common compromise in cellular and satellite links. As β rises toward unity the time response is more compact — easier on symbol timing — at the cost of doubled occupied bandwidth.

<iframe src="https://embed.potik.org/bpsk-noise" />