Intrinsic random functions for mitigation of atmospheric effects in terrestrial radar interferometry

Butt, Jemil Avers; Conzett, Stefan

doi:10.1515/jag-2016-0042

Cited by 8 publications

(3 citation statements)

References 9 publications

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“…If the location of an object relative to the radar instrument does not change and all other influences are constant, the phase value in the corresponding bins of the radar image remains the same for subsequent measurements. However, in most practical situations, drifts caused by changing environmental conditions (e.g., temperature and humidity [42,43]) as well as instrumental effects (e.g., stability of tripod and sensor chip temperature) are to be expected on top of noise. Figure 10a-d shows examples of time series of phase values acquired in the previously described indoor and outdoor experiments.…”

Section: Meteorological Impactsmentioning

confidence: 99%

MIMO-SAR Interferometric Measurements for Structural Monitoring: Accuracy and Limitations

2021

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Terrestrial Radar Interferometry (TRI) is a measurement technique capable of measuring displacements with high temporal resolution at high accuracy. Current implementations of TRI use large and/or movable antennas for generating two-dimensional displacement maps. Multiple Input Multiple Output Synthetic Aperture Radar (MIMO-SAR) systems are an emerging alternative. As they have no moving parts, they are more easily deployable and cost-effective. These features suggest the potential usage of MIMO-SAR interferometry for structural health monitoring (SHM) supplementing classical geodetic and mechanical measurement systems. The effects impacting the performance of MIMO-SAR systems are, however, not yet sufficiently well understood for practical applications. In this paper, we present an experimental investigation of a MIMO-SAR system originally devised for automotive sensing, and assess its capabilities for deformation monitoring. The acquisitions generated for these investigations feature a 180∘ Field-of-View (FOV), distances of up to 60 m and a temporal sampling rate of up to 400 Hz. Experiments include static and dynamic setups carried out in a lab-environment and under more challenging meteorological conditions featuring sunshine, fog, and cloud-cover. The experiments highlight the capabilities and limitations of the radar, while allowing quantification of the measurement uncertainties, whose sources and impacts we discuss. We demonstrate that, under sufficiently stable meteorological conditions with humidity variations smaller than 1%, displacements as low as 25m can be detected reliably. Detecting displacements occurring over longer time frames is limited by the uncertainty induced by changes in the refractive index.

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Section: Meteorological Impactsmentioning

confidence: 99%

MIMO-SAR Interferometric Measurements for Structural Monitoring: Accuracy and Limitations

2021

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“…Because the universal Kriging process falls into a circular problem where the drift form should be known in the Kriging system although the drift form should be estimated through the universal Kriging system, we herein apply the IRFk Kriging to predict res φ . The IRF-k Kriging is introduced for the simultaneous estimation of the drift model and the covariance function [28], [36]. In this method, the drift and the covariance are decomposed through increments of a sufficient order to filter out the drift and achieve stationarity [26].…”

Section: B Residual Aps Prediction In Spacementioning

confidence: 99%

“…Precise analysis of the structural characteristic by the geostatistical approach is thus appropriate for modeling of the short-scale APS component based on the elementary Kolmogorov turbulence theory [27]. Therefore, the analysis and inference of the structure-function and the covariance are essential to mitigate the fluctuated APS [15], [28]. Under the second-order stationarity assumption, the covariance function is inferred by a theoretical variogram to model the uncertain spatial variation [29].…”

Section: Introductionmentioning

confidence: 99%

Iterative Atmospheric Phase Screen Compensation for Near-Real-Time Ground-Based InSAR Measurements Over a Mountainous Slope

Izumi

Zou

Kikuta

et al. 2020

IEEE Trans. Geosci. Remote Sensing

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In this paper, an atmospheric phase screen (APS) compensation algorithm for a near real-time Ground-Based InSAR (GB-InSAR) over a mountainous area is investigated. A novel APS compensation scheme is proposed to compensate the fluctuated APS caused by a spatial 3D inhomogeneous refractivity index distribution without any a priori knowledge of moving location. The proposed method simultaneously addresses to identify moving pixels by a criterion of absolute velocity estimated by the Coherent Pixels Technique (CPT). The proposed method consists mainly of three steps; (1) the stratified APS compensation, (2) identification of moving pixel candidate, and (3) the residual APS (remained APS after (1)) compensation by Kriging interpolation. The steps mentioned above are iteratively applied in order to increase the accuracy of the whole process. In this framework, we develop the 2D quadratic polynomial model of the refractivity index with respect to slant range and topographic height for modeling the stratified APS. Furthermore, a prediction of the residual APS is achieved by applying the IRF-k Kriging interpolation, taking into account the non-stationarity of the residual APS. We evaluate the proposed method using zerobaseline GB-DInSAR data over a mountainous area located in Minami-Aso, Kumamoto, Japan through the near real-time postlandslide measurement campaign.

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On the impact of rockfall catch fences on ground-based radar interferometry

Frukacz

2017

Landslides

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Rockfalls are major natural hazards in mountainous regions and as such monitored if they pose a high risk to people or infrastructure. Ground-based radar interferometry is a relatively new technique suitable for such monitoring. It offers the potential for determining sub-mm-to mm-level displacements by remote measurements under various weather conditions. To avoid damage from smaller rocks and debris, critical surfaces are often protected by rockfall catch fences. We present an experimental investigation proving that the radar measurements are indeed significantly affected by a catch fence made of steel even if its mesh size is larger compared to that of the wavelength of the radar. A stable rock wall in a quarry was monitored by means of a ground-based synthetic aperture radar for 2 days. Different fences varying in shape, size, and density of mesh and in various geometrical configurations were erected at different locations for short periods of time during the experiment. We show that for surfaces observed through the fence, the reflected power can be reduced by 20 dB and thus the signal-to-noise ratio is significantly deteriorated. We also observed spurious interferometric phase shifts. Even parts of the rock wall not covered by the fences are affected. Side lobes and mixed pixels result, e.g., in severe loss of coherence and thus potentially mask actual displacements.

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Intrinsic random functions for mitigation of atmospheric effects in terrestrial radar interferometry

Cited by 8 publications

References 9 publications

MIMO-SAR Interferometric Measurements for Structural Monitoring: Accuracy and Limitations

MIMO-SAR Interferometric Measurements for Structural Monitoring: Accuracy and Limitations

Iterative Atmospheric Phase Screen Compensation for Near-Real-Time Ground-Based InSAR Measurements Over a Mountainous Slope

On the impact of rockfall catch fences on ground-based radar interferometry

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