Cross-Range Velocity Estimation Accuracy in a Space-Based SAR-GMTI System

Analysis is performed to determine the best possible estimation accuracy, in the form of the Cramer-Rao Lower Bound (CRLB), of scatterer cross-range velocity from a single-aperture, space-based platform performing Synthetic Aperture Radar (SAR) and Ground Moving Target Indication (GMTI) functions, with the caveat of the radar signal processor being able to make such a measurement. Simulation results of the CRLB for a nominal space-based system show cross-range velocity estimation errors on the order of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1 ~\mathrm{m} / \mathrm{s}$</tex> are achievable with sufficient signal to noise ratio (SNR) and dwell time. Given radar systems do not inherently measure scatterer cross-range velocity, a modified back-projection algorithm is proposed and implemented to estimate scatterer cross-range velocity in a SAR operating mode. Monte Carlo simulation results for the nominal system show the algorithm nearly obtains the CRLB for cross-range velocity estimation.