Model order selection in multi-baseline interferometric radar systems

Synthetic aperture radar interferometry (InSAR) is a powerful technique to derive three-dimensional terrain images. Interest is growing in exploiting the advanced multi-baseline mode of InSAR to solve layover effects from complex orography, which generate reception of unexpected multicomponent signals that degrade imagery of both terrain radar reflectivity and height. This work addresses a few problems related to the implementation into interferometric processing of nonlinear algorithms for estimating the number of signal components, including a system trade-off analysis. Performance of various eigenvalues-based information-theoretic criteria (ITC) algorithms is numerically investigated under some realistic conditions. In particular, speckle effects from surface and volume scattering are taken into account as multiplicative noise in the signal model. Robustness to leakage of signal power into the noise eigenvalues and operation with a small number of looks are investigated. The issue of baseline optimization for detection is also addressed. The use of diagonally loaded ITC methods is then proposed as a tool for robust operation in the presence of speckle decorrelation. Finally, case studies of a nonuniform array are studied and recommendations for a proper combination of ITC methods and system configuration are given

Single-look light-burden superresolution differential SAR tomography

Research and application is spreading of techniques of coherent combination of complex-valued synthetic aperture radar (SAR) data to extract rich information even on complex observed scenes, fully exploiting existing SAR data archives, and new satellites. Among such techniques, SAR tomography stems from multibaseline interferometry to achieve full-3D imaging through elevation beamforming (spatial spectral estimation). The Tomo concept has been integrated with the mature differential interferometry, producing the new differential tomography (Diff-Tomo) processing mode, that allows `opening' the SAR cells in complex non-stationary scenes, resolving multiple heights and slow deformation velocities of layover scatterers. Consequently, the operational capability limit of differential interferometry to the single scatterer case is overcome. Diff-Tomo processing is cast in a 2D baseline-time spectral analysis framework, with sparse sampling. The use of adaptive 2D spectral estimation has demonstrated to allow joint baseline-time processing with reduced sidelobes and enhanced height-velocity resolution at low computational burden. However, this method requires coherent multilooking processing, thus does not produce full range-azimuth resolution products, as it would be desirable for urban applications. A new single-look adaptive Diff-Tomo processor is presented and tested with satellite data, allowing full range-azimuth resolution together with height-velocity sidelobe reduction and superresolution capabilities and the low computational burden

4D Characterization of Short- and Long-term Height-varying Decorrelated Forest SAR Backscattering

Pol-InSAR and 3D multibaseline SAR Tomography (Tomo-SAR) can extract rich information on complex scenarios with multiple scatterers mapped in the SAR cell, in particular for forest remote sensing. However, forest scenarios are characterized by a temporal decorrelating volume canopy scatterer, and a set of related open problems exists, in particular for Tomo-SAR techniques to be applied to spaceborne monitoring of biomass. Multipass 4D Differential Tomography (Diff-Tomo) is a promising advancement, furnishing space (height)-time signatures of multiple scatterer dynamics in the SAR cell, originally with urban applications. In this paper, to better characterize forest decorrelation phenomena impacting Tomo-SAR/Pol-InSAR, experimental results are presented of the extension of Diff-Tomo methods for analyzing vegetated scenes, to extract jointly geometric and dynamic information of forest layers, at both the long and short time scale. The Diff-Tomo enabled functionality of separation in the height dimension of different temporal coherence levels (“coherence profilingâ€) that are mixed (undiscriminated) in classical total coherence analyses is extensively applied to airborne P-band multipolarimetric data, and results of this investigation are shown. Also, first ground-based radar results are presented of an innovative profiling along the height dimension of the short-term coherence, in particular aiming to characterize the magnitudes of short-term coherence times. Their expected variability along the tree structures is confirmed for the first time

A phase-based technique for localization of uhf-rfid tags moving on a conveyor belt: Performance analysis and test-case measurements

A new phase-based technique for localization and tracking of items moving along a conveyor belt and equipped with ultrahigh frequency-radio frequency identification (UHF-RFID) tags is described and validated here. The technique is based on a synthetic-array approach that takes advantage of the fact that the tagged items move along a conveyor belt whose speed and path are known apriori. In this framework, a joint use is done of synthetic-array radar principles, knowledge-based processing, and efficient exploitation of the reader-tag communication signal. The technique can be easily implemented in any conventional reader based on an in-phase and quadrature receiver and it does not require any modification of the reader antenna configurations usually adopted in UHF-RFID portals. Numerical results are used to investigate the performance analysis of such methods, and also to furnish system design guidelines. Finally, the localization capability is also demonstrated through a measurement campaign in a real conveyor belt scenario, showing that a centimeter-order accuracy in the tag position estimation can be achieved even in a rich multipath environment

Complexity of patients with chronic obstructive pulmonary disease hospitalized in internal medicine: a survey by FADOI

Chronic obstructive pulmonary disease (COPD) is one of the most frequent pathologies among patients hospitalized in Internal Medicine (IM) Departments. COPD is frequently associated with concomitant diseases, which represent major causes of death, and affect disease management. Objectives of our study are to assess the prevalence of COPD patients in IM, to evaluate their comorbidity status, and to describe their complexity, by means of the validated multidimensional prognostic index (MPI) score. COMPLEXICO is an observational, prospective, multicenter study, enrolling consecutive patients hospitalized for any cause in IM, with diagnosis of COPD documented by spirometry. A total of 1002 patients in 43 IM Units in Italy were enrolled. The prevalence of COPD in IM was found to be 18.1%, and 72.8% of patients had at least three chronic diseases other than COPD. The mean MPI was 0.43±0.15, and according to a stratification algorithm 31.8% of patients were classified as having low-risk, 58.9% moderate-risk and 9.3% severe-risk of adverse outcome. More than two-thirds of COPD patients in our study present moderate to severe risk of poor outcome according to the MPI stratification

Polarimetric Differential-TomoSAR Imaging

Recently, in parallel to the maturation of the operative InSAR techniques based on phase-only data, much interest has grown in techniques based on the coherent combination of SAR images at the complex (amplitude and phase) data level, for the extraction of a more rich information on the observed scene. In particular Tomographic SAR techniques constitute the frontier of this research area. Recently, the Differential Tomography framework has also been introduced and experimented, producing ‘space-time’ signatures of multiple non stationary scatterers superimposed in a SAR cell. To further increase the amount of information which can be extracted, in this work we extend the Differential Tomography framework in a polarimetric sense, allowing the extraction of joint information about the heights, the deformation velocities and the scattering mechanisms characterizing the imaged scatterers. First real data samples are presented of the new Polarimetric Differential Tomography concept

Superresolution Differential Tomography: Experiments on Identification of Multiple Scatterers in Spaceborne SAR Data

Interest is growing in the application of coherent processing of synthetic aperture radar (SAR) data to the monitoring of complex urban or infrastructure areas. However, such scenarios are characterized by the layover phenomenon, in the presence of which conventional interferometric SAR techniques degrade or cannot operate. As a consequence, to monitor reliably a high number of ground structures, the identification, i.e., the detection and height and deformation velocity estimation, of both single and multiple scatterers interfering in the same SAR cell can be a key step. This issue is addressed here by means of differential tomography (Diff-Tomo), a recent multibaseline�multitemporal generalized interferometric framework which allows to resolve multiple moving scatterers at different heights in the same cell. In particular, superresolution adaptive Diff-Tomo is extensively tested and augmented with a new information extraction algorithm for the automated identification of the multiple scatterers. Experiments have been carried out with real C-band spaceborne data over urban areas; corresponding results are shown and discussed

On Extended Source Localization in Multibaseline and Multifrequency SAR Interferometry

Publication in the conference proceedings of EUSIPCO, Tampere, Finland, 200