Fig. 1

Operating Principle of the Home cage Activity Detection System. Movements of a small animal modulate and reflect the emitted 10.525 GHz radar waves via Doppler shift. This deviation from the emission frequency is sensed by the X-Band Motion Detector and an internal circuitry generates logic +5V signals according to the velocity of the animals motion. These multiple pulses of short and variable duration are transformed by the Motion Detector Shield to >1 s retriggerable pulses, and allows a downstream Arduino microcontroller board to reliably poll its I/O ports. Detected movement activity will be written to a SD card in *.csv* format with a timestamp from the realtime clock and Python scripts allow the analysis and generation of actograms