Capon-LS for model order selection of interferometric SAR signals corrupted by multiplicative noise

The problem of estimating the number of components in a multibaseline interferometric synthetic aperture radar (InSAR) signal in the presence of layover is made very difficult and atypical due to the appearance of multiplicative noise, the speckle. In fact, all the approaches proposed in literature have been conceived to deal with constant amplitude signals. In particular, the information theoretic criteria (ITC) with signals embedded in additive white noise. As a consequence, in the presence of multiplicative noise, they operate under model mismatch. In a previous work, the ITC robustness to speckle and the possible improvement derived from the application of diagonal loading technique has been investigated. In this paper, a more powerful ad-hoc algorithm for model order selection, based on Capon and least squares method is developed. Its performance is analyzed via Monte Carlo simulation and compared with those of ITC, under different operational InSAR scenarios.