An Investigation of GPS-Denied Navigation Using Airborne Radar Telemetry

A supplementary sensor being explored in the field of GPS-denied navigation is Synthetic Aperture Radar (SAR) with its resulting images. In contrast to passive, camera-based methods, SAR provides illumination of a scene, direct measurement of range, and can operate day and night or through incliment weather. The research presented in this paper investigates the feasibility of using range and range-rate measurements from a SAR system to perform GPS-denied navigation. In support of this research, a 6DOF aircraft navigation and radar simulation is developed and presented. The core sensor used to propagate the navigation states is an inertial measurement unit, corrupted by bias and noise. An indirect extended Kalman filter (EKF) is developed and the covariance of estimation errors is validated via Monte Carlo analysis.