PERFORMANCE OF INTERPULSE SIGNAL CODING IN INTERLEAVED-PULSE POLARIMETRIC SAR

Fully polarimetric Synthetic Aperture Radars (SAR) provide a complete measurement of the scattering matrix of the imaged target by alternate ly transmitting two pulses at orthogonal polarizations, while processi ng echoes simultaneously received on two orthogonal polarization chann els. Due to this procedure of performing measurements, the problem of interference caused by range ambiguities is of greater concern than in conventional non-polarimetric SAR. Such interference is made up by si gnals of different nature, depending on the order (even or odd) of the range ambiguity. In particular, odd-order range ambiguities generate an interference on crosspolar terms of the matrix, proportional to one of the copolar terms, which have typically a much greater magnitude. This drawback, that never occurs in non-polarimetric SAR systems, is a major source of measurement contamination, in particular in the prese nce of range ambiguous echoes from areas which are illuminated at low incidence angles. In this paper, after discussing the influence of ran ge ambiguities on the accuracy of scattering matrix measurement as per formed by interleaved-pulse SAR, we examine the utility of appropriate interpulse phase coding strategies, to be devised and utilized with t he purpose to reduce the interference due to range ambiguities and aff ecting those target scattering matrix elements, whose measurement is e xpected to be most critical.