VectoraLab Lab

Spectrogram: Time-Frequency Map A spectrogram shows frequency content as a function of time. It is computed using Short-Time Fourier Transform (STFT). Computation: 1. Divide signal into overlapping short windows 2. Compute FFT for each window 3. Display as 2D map: time (X) vs frequency (Y) vs amplitude (color) Applications: • Run-up / coast-down: detect critical speeds, resonances • Variable-speed machines: track order frequencies • Intermittent faults: see when they appear • Non-stationary processes Time-Frequency Tradeoff (Heisenberg Uncertainty): You cannot have perfect time resolution AND perfect frequency resolution simultaneously: • Short windows → good time resolution, poor frequency resolution • Long windows → poor time resolution, good frequency resolution Use the Spectrogram Analyzer tool for interactive visualization.