Airborne GMTI radar position bias estimation using static-rotator targets of opportunity

In target tracking systems using GMTI (ground moving target indicator) rada rs on airborne platforms, the locations of these platforms are available fr om GPS-based estimates. However, these estimated locations are subject to e rrors that are, typically, stationary autocorrelated random processes, i.e, , slowly varying biases. In situations where there are no known-location ta rgets to estimate these biases, the next best recourse is to use targets of opportunity at fixed but unknown locations. Such targets can be, e.g., sta tic rotators (ground-based radars with rotating antenna), which yield detec tions in moving target indicator (MTI) radars. It is shown that these biase s can be estimated in such a scenario, i.e., they meet the complete observa bility condition. Following this, the achievable accuracy for a generic sce nario is evaluated. It is shown that accurate georegistration can be obtain ed even with a small number of measurements.