Millimeter-Wave Interferometric Radar for Speed-Over-Ground Estimation
In this work we present a V-band interferometric millimeter-wave continuous-wave (CW) radar operating at 42.875 GHz for vehicle speed-over-ground estimation. The system points normal to the road-surface providing a constant target range and radar cross-section (RCS), and thus a deterministic signal-to-noise ratio (SNR) compared to outward-looking systems. Interferometric processing is performed by correlating the received signal responses from a pair of antennas separated by a baseline of 8 lambda. The system is designed with three independent phase-quadrature receive channels to allow for a pair of orthogonal baselines. On-vehicle measurements were performed for a single baseline parallel to the direction of travel and velocity was estimated directly from the received radar spectrum. The estimator consists of a fully-connected feedforward neural network (NN) with smoothing which achieved a root-mean-squared error (RMSE) of 0.0204 m/s on a 2-minute data capture.