Permanent scatterers in space-surface bistatic SAR using Beidou-2/Compass-2 as illuminators: Preliminary experiment results and analysis

Beidou-2/Compass-2 inclined geosynchronous orbit satellites have short revisit time, which provides possibility for bistatic SAR differential interferometry application. But the orbit is not accurately repeated and the baseline grows with the time, which can result in deteriorating spatial coherence coefficient and may invalidate the tradition differential interferometry method. In order to implement accurate deformation monitoring, permanent scatterer technique could be utilized. However, the existence of permanent scatterers in this kind of system has not been demonstrated so far. In this paper, validation experiments are presented to validate the feasibility for SS-BiSAR differential interferometry using permanent scatterers. The echoes of urban region in 10 different days with time span of 12 days are collected and processed. The coherences coefficients between different days and the amplitude dispersion are analyzed. The result shows that under the amplitude dispersion threshold of 0.25 many pixels can be identified as permanent scatters. Thus the existence of permanent scatterers in this kind of system is demonstrated, showing its potential to implement local area deformation monitoring.