Extraction of Doppler signature of micro-to-macro rotations/motions using continuous wave radar-assisted measurement system

Mechanical-structural vibration and/or rotational parts of the targets will induce micro-Doppler frequency in addition to the main Doppler components. In the today's military era, detections, measurements and decision making have to be made after the thorough analysis of main and micro-Doppler signatures of the targets to get their full profile particularly for defence applications. In addition, few of the low radar cross-section targets can be detected only by extracting and processing the micro-Doppler signatures corresponding to the rotations of their propellant rotor blades. Therefore, experimental studies to measure the micro-to-macro rotation/motion generated Doppler frequency and performing its associated measurements become significant. The authors built a C-band (5.3 GHz) continuous wave radar and used it to measure the Doppler frequency generated by micro-to-macro rotations/motions. The detection and measurement accuracy of the developed radar is assessed by series of different open-environment experimental case studies: revolution per minute measurement of rotating blades, separation of multiple rotating blades, oscillation per minute measurement of a swinging pendulum, detection of approaching/receding motion and the Doppler signature extraction of walking/jogging/cycling person. All these measurement values are validated against the standard master instrument readings and theoretical calculations. Finally, the limitations of this system and required near-future research works to enhance its performance are listed.