Passive Source Localization Using an Airborne Sensor Array in the Presence of Manifold Perturbations

This paper studies localizing sources of electromagnetic energy using a passive sensor array whose manifold is only nominally known. The problem of source localization is studied in the context of an airborne array that is able to observe a ground-based source from multiple angles. External and self-calibration algorithms are developed as a means to obtain accurate source localization estimates when the sensor manifold is perturbed. External calibration establishes the expected difference between the actual and modeled array manifold using signals at known locations. Self-calibration assumes that this expected difference is known only approximately and relies on signals of opportunity in the environment to provide updates. Several novel calibration algorithms are proposed, and their performance is tested on experimental data. The results indicate that significant performance gains are achieved with the use of the proposed calibration algorithms