A Joint Space-Time Approach to Persistent Scatterer Interferometry

Mario Costantini(1) , Massimo Guglielmi(1) , Fabio Malvarosa(1) , and Federico Minati(1)

(1) Telespazio S.p.A., Via Tiburtina, 965, 00156 Roma, Italy


The phase measurements obtained with differential synthetic aperture radar (SAR) interferometry contains valuable information on slow terrain movements. Unfortunately, the phase is affected by random noise (due to decorrelation between the signals of different acquisitions), and systematic terms (due to inaccurate orbital data and reference digital elevation model, and different atmospheric conditions at the various acquisition dates). The points characterized by too high random noise must be recognized by means of statistical estimations and discarded. The systematic terms can be recovered using statistical or deterministic models for the disturbances to be eliminated and the signals to be determined.

In the respect of the problem above, key advances were introduced by the persistent scatterer approach, in particular the ideas of minimizing the amplitude and phase dispersions in long series of SAR acquisitions. This approach exploits mainly the temporal properties of the signals, while the spatial characteristics are not optimally used. On the contrary, other approaches, more similar to classical differential interferometry, exploit first the spatial and then the temporal properties of the data.

In this work, we propose a technique that better exploits the spatial and temporal properties in order to select the points characterized by low random noise and determining the various components of the signal. Considering jointly the spatial and temporal structure of the data allows recognizing properties of the signals that help in recovering the correct solution. Tests performed on simulated and real ERS data show that the proposed approach is promising.


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