Simultaneous Measurement of Radial and Transversal Velocities Using Interferometric Radar

The linear velocity of an arbitrary moving object comprises two orthogonal components with reference to the observing radar, which are radial velocity and transversal velocity. Simultaneous measurement of both the radial and transversal velocities can provide a complete 2-D movement information for further target detection, tracking, and classification. The interferometric radar is capable of measuring the 2-D velocity of an arbitrary moving object simultaneously, regardless of the trajectory. However, the radial velocities and transversal velocities are coupled in the interferometric measurement due to the nonlinear processing when there are multiple moving objects in the radar field of view (FoV), thus the conventional time-frequency analysis fails to measure the transversal velocities. In this article, we first derive and analyze the signal distortion caused by the nonlinear interferometric operation. We then propose two new methods of combining the inverse Radon transform (IRT) and short-time Fourier transform (STFT), which can concentrate a sinusoidally frequency-modulated waveform from time-frequency domain into a point in the parameter domain, thus separating the transversal velocity measurements of different objects with rigid-body rotations. Simulation and experimental results are provided to validate the effectiveness of the proposed methods.