Estimating Signal-to-Clutter Ratio of InSAR Corner Reflectors From SAR Time Series

The estimation of Signal-to-Clutter Ratio (SCR) of a radar point target, such as a corner reflector, is an essential step for synthetic aperture radar (SAR) interferometry and positioning, as it influences the phase measurement variance as well as the absolute positioning precision. The standard method to estimate the SCR of a point target relies on the debatable assumption of spatial ergodicity, using the clutter of the surrounding as representative of the clutter at the point target. Here, we estimate the SCR of a corner reflector using a time series of SAR measurements, i.e.,\ assuming temporal ergodicity. This assumption is often more realistic, particularly in a complex environment, in the presence of other point scatterers, and for small-sized reflectors. Empirical results on a corner reflector network, using Sentinel-1 SAR measurements, show that the temporal method yields a less biased and more precise estimate of the average SCR. A second experiment shows that the InSAR phase variance as well as positioning precision, predicted using SCR estimated by the temporal estimation method, is closer to the truth.

Automated summary

In this study, the Signal-to-Clutter Ratio (SCR) of a radar point target, such as a corner reflector, was estimated using a time series of SAR measurements, assuming temporal ergodicity. The results showed that the temporal method provided a less biased and more precise estimate of the average SCR compared to the traditional method relying on spatial ergodicity assumption. Additionally, the use of SCR estimated by the temporal estimation method led to closer predictions of InSAR phase variance and positioning precision.