Dual Interferometric-Doppler Measurements of the Radial and Angular Velocity of Humans

The first measurements of moving humans using a dual-mode millimeter-wave radar sensor are presented. The radar sensor is comprised of a Doppler detection mode for measuring the radial velocity of a moving object, as well as a recently developed interferometric mode for directly measuring the angular velocity. Combining the two detection modes, it is shown that the motion of a walking human can be detected and measured regardless of the direction of trajectory relative to the radar sensor. Such a capability has the potential to significantly improve the effectiveness of security radars, and may apply to a broad range of other motion detection radar applications. The frequency shifts imparted on the signal in both Doppler and interferometric detection modes are measured in the time-frequency domain, and show that as the trajectory moves from a completely radial motion to a completely angular motion, the Doppler frequency shift decreases while the interferometric frequency shift increases. The two detection modes therefore represent complementary measurements, improving the ability to measure the motion of randomly moving objects.