A Compensation Method for a Time–Space Variant Atmospheric Phase Applied to Time-Series GB-SAR Images

Abstract

An atmospheric effect is a main error source that affects interferometric measurements. When a ground-based multiple-input multiple-output (GB-MIMO) radar, i.e., a specific type of GBsynthetic aperture radar (GB-SAR), was utilized to continuously monitor an open-pit mine, the interferometric phases of some interferograms were complexly space-variant due to time-variant weather conditions. The conventional method of atmospheric phase (AP) compensation was no longer applicable. This paper proposes an improved compensation method of a time-space variant AP applied to time-series GB-SAR images. The permanent scatterers (PSs) were classified into three types based on their different spatial properties: The noise-dominant PS (NPS), the deformationdominant PS (DPS), and the atmospheric effect-dominant PS (APS). The NPSs were firstly rejected based on the differential phase analysis of neighboring PSs. The DPSs were then rejected based on the cluster partition and selection. With the APSs, the space-variant AP was estimated with a spatial interpolation. To validate the feasibility of the proposed method, short-term and long-term experimental datasets were processed. Comparisons with a conventional method proved that the proposed method can well reduce AP errors and avoid the misunderstanding of motional areas.

Temporal Coherence Estimators for GBSAR

“…Given the promising results obtained with simulations, authors of this paper aimed to validate Equation (16) for experimental data acquired in natural scenarios. That is, determining whether the simplified model introduced in Section 2, could effectively describe the scattering properties of different physical scenarios.…”

“…Other sources of de-coherence, such as the atmospheric condition, could be compensated during the signal analysis. Indeed, these contributions are not related with the quality of the signal and can be removed by using specific techniques [13][14][15][16][17][18] before coherence computing.…”

“…Remote Sens. 2022, 14, 3039 2 of 16 The amplitude dispersion index (D A ) [6,7] was introduced for the determination of the so-called permanent scatterers, i.e., targets whose signal amplitude remains stable over time, and it is a popular tool currently employed in interferometric analysis.…”

High-Quality Pixel Selection Applied for Natural Scenes in GB-SAR Interferometry

“…It should be noted that the complex phase exp(jϕ Clu ) rather than the wrapped phase ϕ Clu should be used for interpolation. Subtracting ϕ Spa from ϕ Int , the residual phase is ϕ noi [17].…”

“…ϕ should be used for interpolation. Subtracting S p a ϕ from Int ϕ , the residual phase is noi ϕ[17].…”