Why Welch PSD Alone Often Misleads Tonal Detection in Noisy DSP Systems
Introduction Power spectral density estimation using Welch’s method is a standard tool in digital signal processing. It is widely taught, easy to compute, and effective for identifying stationary frequency content. However, engineers frequently encounter confusing behaviors when using Welch PSD for tonal noise detection in real systems: peaks appear and disappear between measurements ripple artifacts resemble narrowband interference drifting tones smear into broadband humps weak interference vanishes under averaging These effects often lead to incorrect notch placement, missed suppression, or unstable filter designs. ...