Non-linear techniques for estimating non-stationary spatial spectra

The problem of estimating the distribution of energy arriving at an array as a function of bearing is central to many array processing applications. To form such spatial spectral estimates, data is collected over an interval of time. If the geometry between the source and receiver varies over that interval then the spatial spectral estimator will lose resolution. This work describes a methodology for mitigating this loss based on employing higher order correlation matrices that are robust to such non-stationarities