Multi-chromatic analysis of a single SAR image for absolute ranging

The Multi-Chromatic Analysis (MCA) uses interferometric pairs of SAR images processed at range sub-bands located at different spectrum positions, and explores the phase trend of each pixel in the frequency domain. By exploring the linear phase trend along the sub-bands frequencies, both phase unwrapping as well as height computation can be performed on a pixel by pixel basis without spatial integration. This work is aimed at experimenting a further application of MCA consisting in processing a single SAR acquisition for measuring the optical path between the SAR sensor and the imaged scene. We used TerraSAR-X SAR data acquired in Spotlight mode over the Venice Lagoon, and took advantage of corner reflectors already deployed for other purposes which guarantee phase stability as well as precise geographical positioning. We computed the delay induced by the atmosphere on the SAR signal, then compared this measure with that derived by analytical models and in situ records.