Noise analysis of the high resolution methods in ISAR

Commonly used technique for the inverse synthetic aperture radar (ISAR) signal analysis is a two dimensional Fourier transform. Short time intervals could be used in order to reduce nonstationarity effects. However, resolution of images obtained by using short intervals is highly limited. In this case superresolution techniques, such as Capon, ESPRIT and MUSIC, should be used. All high resolution methods are quite sensitive to the noise. The main topic of this paper is to find a relation between maximum SNR and resolution when 2D Capon method is used in ISAR. 2D Capon method´s sensitivity to the noise is analyzed and compared to the 2D Fourier transform application, in case of well separated scattering centers. In order to improve performance of the standard Capon method a modified version with the known number of components is considered.