Low SNR

Introduction In low-SNR environments, PSD-based peak detection often becomes unstable. Spectral variance, leakage, and noise ripple cause dominant frequency bins to shift randomly between measurements. As discussed in Why PSD Peak Detection Fails in Low SNR Signals, the core issue is not mathematical correctness — it is the loss of determinism. Short-Time Fourier Transform (STFT) introduces temporal structure into spectral analysis, enabling engineers to separate true tonal interference from stochastic noise behavior. ...

Introduction Power Spectral Density (PSD) peak detection is one of the most common tools used in DSP pipelines to identify tonal interference. In high-SNR scenarios, it works well. In low-SNR signals, however, PSD peak detection often becomes unstable, misleading, or outright wrong. Engineers frequently encounter situations where: spectral peaks appear and disappear between measurements different averaging parameters produce different “dominant tones” automatic notch insertion removes non-existent interference weak real tones are missed entirely This article explains why PSD peak detection becomes unreliable at low SNR — not from a theoretical standpoint, but from an engineering systems perspective. ...