Description
Micro-Doppler signatures are the time-frequency patterns produced by sub-body parts (limbs, chest wall, fingers) on top of bulk body Doppler. The classic example is gait: torso fundamental at ~1 Hz Doppler, with arm and leg harmonics at multiples. They are the discriminative feature for gait, gesture, and fall classification in both WiFi-CSI and radar pipelines.
When it's used
- Identity / activity / gesture classification
- Vital-sign sensing (chest-wall micro-Doppler)
- Distinguishing fall from sit-down
Limitations
- Requires narrow-band Doppler resolution → longer windows
- Multi-person micro-Doppler interferes on the same bins
- Susceptible to clutter without spatial separation