Stochastic Resonance & Dithering

Noise enhances detection of subthreshold signals — dithering in analog-to-digital conversion

Signal Parameters

Signal amplitude A 0.60 Threshold θ 1.00 Signal frequency f 0.05 Noise σ 0.50

SNR at Output

SNR = —

Detections: —

Theory

Stochastic resonance: For A < θ (subthreshold), the signal alone never triggers the detector. Adding noise enables occasional threshold crossings — timed with signal peaks → detectable. Optimal noise level maximizes SNR.

Dithering: In ADC, adding controlled noise before quantization reduces systematic bit-pattern distortion. Used in audio (noise-shaping) and image processing since the 1960s.