Single-Look Complex COSMO-SkyMed SAR Data to Observe Metallic Targets at Sea

In this paper, a physically based approach, which takes full benefits of speckle noise as source of information, is first applied over X-band full-resolution single-look complex slant (SCS) COSMO-SkyMed synthetic aperture radar (SAR) data to observe metallic targets at sea. A constant false alarm rate (CFAR) filter based on the coherent-to-incoherent field ratio is developed, which: 1) is very effective in terms of processing time, 2) is able to provide logical true-and-false outputs characterized by a very low false alarm rate; and 3) can operate in a wide range of incidence angles. Experimental results, obtained by processing a wide data set of full-resolution SCS X-band COSMO-SkyMed SAR data, show the effectiveness of the proposed approach. Part of this data set regards the challenging operational case related to the Air France Flight 447 accident occurred on June 1, 2009, off the Brazilian coasts. It is shown how COSMO-SkyMed SAR data can assist the search of aircraft debris at sea. Moreover, the proposed approach is of great applicative relevance even because of the high revisit time of COSMO-SkyMed constellation.