A Point Target Model for Interferometric Radar Angular Velocity Estimation

In this work, we derive the exact response of an interferometric correlation radar to an arbitrary scene containing
$N$
independent point scatterers. The response of an interferometric radar to multiple targets can be complicated by the nonlinear processing, which generates intermodulation responses in addition to the desired fundamental frequency responses. An accurate signal model is critical for predicting and mitigating these intermodulation products and allows for model-based parameter estimation methods to be used to estimate target angular velocity. We derive a general response to an arbitrary number of independent targets and validate both the exact model and a simpler approximate model via simulation and experimental measurement with a 38-GHz continuous-wave interferometric radar. The experiment contains two targets traveling perpendicular to the radar’s line-of-sight on linear stages at speeds of 0.36 and 0.5 m/s. We use an error metric to describe the similarity between the measured or simulated time–frequency response and the time–frequency response of a signal generated using the frequency estimates of either the exact or approximate models and show that in regimes where the small-angle approximation holds, both models provide an accurate representation of the measured or simulated interferometric response, demonstrating the feasibility of these models.