Signal generator & scope

Dual-channel waveforms, triggered scope, spectrum, measurements, and export for HIL-style offline work.

Waveforms

• Sine — single spectral line at f
• Square / pulse — odd harmonics; duty sets mark/space
• Triangle / saw — harmonics ~1/n² (triangle) or ~1/n (saw)
• White / pink noise — broadband; pink ≈ −3 dB/octave
• Chirp — linear sweep between start and end frequency
• AM / FM — amplitude or frequency modulation sidebands
• Arbitrary — looped sample table with linear interpolation

x(t) = A · w(φ(t)) + offset

Sampling & Nyquist

Δt = 1 / fₛ
content above fₛ/2 aliases

Keep tones well below half the sample rate. The scope timebase (ms/div) chooses how much history is drawn.

Triggering

Rising/falling edge on CH1 re-aligns the display buffer at a threshold crossing — similar in spirit to a real digital scope “auto/normal” capture, simplified for teaching.

FFT spectrum

When the window length is a power of two, a Cooley–Tukey FFT computes the magnitude spectrum. Hann windowing reduces leakage. Peak frequency and a rough THD estimate (harmonics 2…8 over fundamental) are shown.

X[k] = Σₙ x[n] e−j 2π k n / N
f_k = k · fₛ / N

Measurements

• Vpp — max − min in the window
• RMS — √(mean x²)
• Freq (est.) — zero-crossing rate (works best on clean periodic signals)

X-Y (Lissajous)

CH1 → X, CH2 → Y. Equal frequencies with 90° phase produce a circle/ellipse; frequency ratios draw classic Lissajous figures.

Export & audio

CSV columns t_s, ch1, ch2 for HIL/co-sim. WAV is a mono mix. Browser audio uses the Web Audio API (looped buffer) — watch levels.