An interferometric SAR processor avoiding phase ambiguities

One of the key problems in SAR interferometry is the determination of the absolute phase of a scatterer by unwrapping the calculated phase difference of two SAR images. Since the phase difference is a function modulo 2π software algorithm are used to perform a phase unwrapping to obtain an unambiguous phase and thus the corresponding height information. This paper presents a procedure using two different transmit frequencies to enlarge the unambiguous range for height determination. Measurements performed in an anechoic chamber are used to test the processing. Using this procedure it is not only possible to resolve the height of a surface but also of single scatterers in space or in urban areas with steep slopes