The Digital Filter That Lagged a Perfect Step
Unity DC gain does not mean instant response. Step through a recursive digital filter and see why its output rises gradually.
Topic: Signal Processing
The 1 kHz Filter That Only Passed 70.7%
Cutoff does not mean fully passed. A first-order low-pass is already at 0.707 amplitude at fc.
The Vibration Sensor That Invented a 300 Hz Tone
A 900 Hz vibration can look like a clean 300 Hz signal when the ADC samples too slowly.