Some results achieved from a reconfigurable stepped frequency GPR system will be presented. The aim is to show the possibilities of a reconfigurable architecture for a GPR system within the non-invasive prospecting of the Cultural Heritage. In particular, two sites (indoor and outdoor, respectively) have been chosen, in order to test the system in different situations that pose different problems. The same sites have been prospected also with a commercial pulsed system, in order i) to work out a comparative heuristic analysis and ii) to plan possible future advancements improving the reconfigurable system.

This contribution aims at assessing the imaging capabilities of a differential configuration for GPR prospecting. In particular, two receiving antennas are piled on each other at the same abscissa, and the transmitting antenna is at a fixed horizontal offset and at the intermediate height between the two receivers. The analysis is carried out with the aid of a microwave tomographic algorithm based on the Born approximation. The considered GPR configuration allows to reject the direct coupling between the antennas in air, but worsens the filtering properties of the relevant scattering operator.

Tricarico Cathedral, dating back to 11th century, nowadays presents widespread damage. The elements which are most damaged and at risk of collapse are the piers of the nave. They consist of a square core surrounded by pilaster strips. Integrated diagnostic investigations have been carried out in order to characterize the structural instability phenomenon which causes the damage, thus providing information useful for restoration interventions. In particular, endoscopic investigations permitted to ascertain the lack of connection between the pilaster strips and the core. The stone has good properties, as verified through ultrasonic tests. Sonic tests and GPR investigations highlighted that the cores of a number of piers present velocities and reflections, respectively, which can be referred to fractures or voids. Moreover, GPR investigations highlighted reflections in the pilaster strips which are typical of a severe and widespread decay, in agreement with visual inspection. Porosity measures were carried out on core samples apparently undamaged, and on an individual sample macroscopically damaged. Measures of ambient vibrations provided the fundamental frequency of structures by the HVSR technique (Horizontal to Vertical Spectral Ratio). The measures were carried out on the soil, the facade, the left aisle and the bell tower. The HVSR is interpreted comparing measures carried out in adjacent structures also with the aim to detect coupling phenomena (double resonance) between the eigenfrequencies of the structural macroelements and the soil.

A prototype of reconfigurable stepped frequency GPR system has been implemented in the framework of the research project AITECH, financed by the Puglia Region (http://www.aitechnet.com/home.html). The prototype has been realized in collaboration between the Institute for Archaeological and Monumental Heritage (IBAM-CNR), the IDS Corporation and the University of Florence, and is now part of the equipment of the Laboratory of applied geophysics to archaeology and monumental heritage (http://www.ibam.cnr.it/pdf/Persico%20in.pdf). The reconfigurability is a theoretically appealing possibility, under study thanks to the availability of this prototypal system. In particular, several case histories have been studied and other ones will be studied in the next years in order to test the reconfigurable system in several situations and under different conditions. The general aim of this work in progress is not only to assess the possibilities of the instrument but also to identify its main limits in order to plan, possibly, the implementation of suitable modifications for the enhancement of its performances. In this papers, some results in sites of cultural interests will be shown, in comparison with the results achieved from a commercial pulsed GPR system. The emphasis is on the benefits of gathering three bands at the same time, related to the kind of anomaly and environment met in the case history at hand.

We present the first application in the field of a reconfigurable stepped frequency system. The system has been designed in collaboration between the Institute for Archaeological and Monumental Heritage IBAM-CNR Lecce, the Department of. Electronics and Telecommuncations of the University of Florence and the Company Ingegneria dei Sistemi IDS S. p. A., Pisa. We show some results achieved in the chapel of the ex hospital of the Holy Spirit in Lecce and we compare them with the results obtained by using a commercial pulsed GPR system.

In this paper, we propose an automated detection algorithm for well-and ill-shaped ground-penetrating radar reflection hyperbolas for complex media, calibrated with human recognition principles. The algorithm detects the apex of the hyperbolas by fitting an analytical function of a hyperbola to the profile edge dots detected with a Canny filter. The existence of a hyperbola is determined using a set of carefully chosen criteria calibrated in order to fit the ambiguity zone for the human brain. The inherent misshapedness of field hyperbolas is further considered by defining a buffer zone around the theoretical hyperbola. First, the method was tested in the laboratory over tree roots and PVC pipes and on field images over tree root systems. Both time-and frequency-domain radars were used on-ground. After around 1-3 min of computation time for 10 000 edge dots in a MATLAB environment (single 1.96-GHz processor), the results showed rates of false alarm and nondetection of maximum 20% and 28%, respectively. In comparison with the semiautomated hyperbola detection provided by a commercial software, these rates were lower. Second, we conducted a sensitivity analysis to estimate the validity of the fitting of a hyperbola equation neglecting the object radius. The fitting was close, but the derivation of the relative permittivity from the analytical equation neglecting the radius led to high errors. In conclusion, owing to the low computational time and its good performances, the proposed algorithm is suitable for complex environments.

A crucial question in imaging problems from diffracted wavefields is the evaluation of the information content of data and the related reconstruction performance in terms of spatial resolution. It is well-known that full-view tomographic reconstructions are characterized by resolution limits of the order of one half propagated wavelength. These limits are further deteriorated when a truncated measurement domain is exploited for the imaging. In this Letter, we show that when the imaging system comprises a periodic layer located between a linear array of probes and the investigated domain, the resolution limits are substantially improved compared to the case of a homogenous scenario. This intriguing result is a consequence of the multiscattering effects arising from the periodicity of the structure. The study provides physical insight supported by mathematical arguments paving the way to the development of effective imaging systems requiring few radiating elements. (c) 2014 AIP Publishing LLC.

In this paper, we present the results of a diagnostics survey, based on the exploitation ofground penetrating radar (GPR) and sonic prospecting, to characterize the deterioration statusof the pillars of the cathedral of Tricarico, in the Basilicata region (Southern Italy). Theprospecting falls within the more general framework of investigating the structural conditionsof this monument, which is affected by heavy instability problems. This study case points outthe great effectiveness of the two employed diagnostic methods, when used in an integratedway, for detecting cracks and inhomogeneities in the inner structure of masonry buildingelements. With regard to GPR prospecting, a comparison is made between the results obtainedby a standard processing and those obtained by means of an inverse scattering algorithm. Forone of the investigated pillars, the results obtained from non-invasive tests are compared withthose of direct inspection. This is performed by coring the pillar and examining both the coreand the hole (the latter by means of an endoscope). The seismic investigation allowed us toprove the mediocre or bad state of conservation of the pillars.

In this paper, we show the results of three case histories where GPR prospecting has beeninterpreted also with the aid of a specific archive research on documents of the XVI and XVIIcentury. The case histories are related to three churches of the renaissance and baroqueperiod in Lecce, Lecce, Southern Italy. The aim is to deliver the usefulness of GPRprospecting in these kind of monuments and to show how the likelihood of the interpretationcan be increased when historical information is available.

The Romano-British site of Barcombe in East Sussex, England, has suffered heavy postdepositional attrition through reuse of the building materials for the effects of ploughing. A detailed GPR survey of the site was carried out in 2001, with results, achieved by usual radar data processing, published in 2002. The current paper reexamines the GPR data using microwave tomography approach, based on a linear inverse scattering model, and a 3D visualization that permits to improve the definition of the villa plan and reexamine the possibility of detecting earlier prehistoric remains.

In this contribution we show the results obtained in relationship with GPR and ultrasonic investigations carried out in the Crypt of the Holy Spirit in Monopoli. The exploitation of integrated techniques has allowed to have a meaningful insight of the presence of interesting buried anomalies under the floor and has provided important information about the state of preservation of the columns.

In this paper, we present a case study conducted in the archaeological park of Egnazia (Apulia, Southern Italy) based on the integrated use of two different ground-penetrating radar systems plus a magnetometer. The surveys were carried out using a pulsed ground-penetrating radar system, a prototypal reconfigurable stepped frequency ground-penetrating radar and a high-resolution magnetometer. The most important anomalies identified are ascribable to the presence of a massive building structure mainly consisting of masonry, probably dating from the Roman age. Emphasis is on the integration of the results, which has made it possible to produce enhanced images. In particular, two different approaches based on (i) algebraic and (ii) RGB combinations of the data gathered with the three sensors are illustrated and discussed.

Illegal excavations represent one of the main risks which affect the archaeological heritage all over the world. They cause a massive loss of artefacts but also, and above all, a loss of the cultural context, which makes the subsequent interpretation of archaeological remains very difficult. Remote sensing offers a suitable chance to quantify and analyze this phenomenon, especially in those countries, from Southern America to Middle East, where the surveillance on site is not much effective and time consuming or non practicable due to military or political restrictions. In this paper we focus on the use of Very High Resolution satel-lite imagery to quantitatively assess looting in Ventarron (Lam-bayeque, Peru) that is one of most important archaeological sites in Southern America. Multitemporal satellite images acquired for the study area have been processed by using both autocorrelation statis-tics and unsupervised classification to highlight and extract looting patterns. The mapping of areas affected by looting offered the op-portunity to investigate such areas not previously systematically documented. To this purpose georadar prospections were conducted in some looted test sites.

In this paper we present the results of a microwave tomography algorithm applied to the GPR data gathered at the archaeological site of North Ballachulish (Scotland). The GPR survey had the aim of mapping the contours of the peat basin and investigating the possibility of archaeological remains. A linear inverse scattering algorithm has been applied on the data, and the results are compared with those achieved by means of the Reflex code. The results of this work show the possibility of applying the linear inverse scattering approach to a massive amount of data for large-scale investigations, and also of showing the possibilities offered in some cases by pre-processing the data (interpolation procedure) so as to improve the result of the overall diagnostics procedure.

The crypt of St. Nicholas in Bari, Southern Italy, is a building of cultural worldwide importance. Inside the crypt a mosaic develops on the apsidal floor and along a parietal seat placed along the apsidal masonry, in the form of cladding. A surviving portion of the mosaic pavement is also preserved in the right lateral chapel. Integrated non-destructive survey and laboratory analyses were undertaken for the diagnostic study of the mosaic. GPR prospection was successfully applied to the study of its conservation state, that is strictly related to the condition of the subsoil, in particular to the presence and distribution of water. The presence of water, whose rise interests also some portions of the masonry and water content distribution were identified by the results of electromagnetic wave velocity analysis in GPR data. The decay visible on the tesserae evidenced widespread spalling and crumbling as typical forms that selectively affect the different materials of the tesserae of the mosaic. Samples taken from them were investigated by optical microscopy, X-ray diffraction, ion chromatography, infrared spectroscopy and thermogravimetric analyses, in order to identify the constituent materials and the products of their decay. The application of the integrated methodologies showed its effectiveness in order to acquire a quite complete knowledge for diagnostic purpose. Decay appeared to be due to the combined presence of water and soluble salts and it has different effects depending on the materials characteristics.

This communication is concerned with the performance achievable within a 3-D inverse scattering approach in relationship with the measurement configuration. The problem is undertaken under the Born approximation, and three configurations are considered, namely a multimonostatic, a single view/multistatic and a multiview/multistatic, all of them in the multifrequency framework. The analysis is worked out with the tools of the diffraction tomography and of the singular value decomposition of the relevant operator. Tomographic reconstructions based on full-wave synthetic data are shown.

We focus on the choice of the investigation domains for a 2-D linear inversion algorithm based on the Born approximation. The application of an inversion algorithm to a wide B-scan requires the subdivision of the data into several observation domains and the partition of the buried scenario into different investigation domains, and this can be done in many ways, which raises the problem of examining the well advisedness of the adopted choice. In particular, here, we will propose the possibility of a double sequence of investigation domains. The results will also be compared with a migration algorithm. © 2004-2012 IEEE.

In this paper three case histories of ground penetrating radar (GPR) for the monitoring of historical buildings are presented. They aim to present the specific valence of the GPR in the field of the diagnostic of historical buildings, which is a promising field of research, due to the increasing awareness of the relevance (even economic) of the cultural heritage. The presented GPR prospecting cases have been performed on three different constructive elements typical of historical buildings (a wall, a masonry pillar and a marble column) in order to be the answer to different problems such as the characterization of the masonry, the detection of cracks and the imaging of metallic reinforcement bars.

In the last few years the environment has constituted a themes of great interest in Europe and in the world, in the framework of the sustainable development of the territories. The relationship between humankind and environment is also essential in order to understand the history of the ancient civilizations. Nowadays, archaeology makes use of advanced methodologies and technologies aimed to the study, the knowledge and the reconstruction of the historical European and Mediterranean landscapes. In Italy, the great variety of different environmental conditions offers a meaningful opportunity for the study of the rural scenarios between the Late Antiquity and the Early Middle Ages. The settlement framework of the southern part of the Apulia region (Italy) results to be quite rich with regard to the Classical period, whereas it has been enhancing only during the last few years with regard to the Late Antiquity and the Medieval Age. In this region, that has been called Terra d'Otranto starting from the Middle Ages, some archaeological excavations in sample areas have revealed a more detailed and documented picture of the settlements in the territory and of its dynamic transformation. In this context, geophysics, archaeometry and virtual reality can found large application. In particular, with regard to the regional transformation dynamics of the settlements between Late Antiquity and Early Middle Ages, the archaeological site of Contrada Badia, placed north-west of today Cutrofiano (in the outskirts of Lecce) is of great interest. Here, an archaeological survey on an area of about 50 hectares has recorded the human frequentation of this area from Bronze Age to Middle Ages. More specifically, two interesting sites have been identified, placed on the two sides of a street leading to the modern town: the first one is deemed to be a rural settlement of the Imperial and Late Antiquity Age, whereas the second one seems to be the site of a medieval abbey. In order to characterize the expected buried structures (and partially already identified by means of aerial photography data) in both sites, a ground penetrating radar (GPR) prospecting has been scheduled and partially already done. The data have been gathered with a pulsed Ris-Hi mode system belonging to the Laboratory of Geophysics applied to Cultural Heritage of IBAM-CNR equipped with a double antenna at 200 and 600 MHz, and have been processed by means of the GPR-Slice software. The present work was carried out within the research project PRIN 2010-2011 (prot.2010H8WPKL-001), UR (CNR-IBAM ) "Innovative Methods for the Reconstruction of the Landscape of Terra d'Otranto between Late Antiquity and Middle Ages".

The crypt of St. Nicholas in Bari, Southern Italy, is a building of cultural worldwide importance. Inside the crypt a mosaic develops on the apsidal floor and along a parietal seat placed along the apsidal masonry, in the form of cladding. A surviving portion of the mosaic pavement is also preserved in the right lateral chapel. Integrated non-destructive survey and laboratory analyses were undertaken for the diagnostic study of the mosaic. GPR prospection was successfully applied to the study of its conservation state, that is strictly related to the condition of the subsoil, in particular to the presence and distribution of water. The presence of water, whose rise interests also some portions of the masonry and water content distribution were identified by the results of electromagnetic wave velocity analysis in GPR data.The decay visible on the tesserae evidenced widespread spalling and crumbling as typical forms that selectively affect the different materials of the tesserae of the mosaic. Samples taken from them were investigated by optical microscopy, X-ray diffraction, ion chromatography, infrared spectroscopy and thermogravimetric analyses, in order to identify the constituent materials and the products of their decay.The application of the integrated methodologies showed its effectiveness in order to acquire a quite complete knowledge for diagnostic purpose. Decay appeared to be due to the combined presence of water and soluble salts and it has different effects depending on the materials characteristics.

In this work, three different techniques, namely time domain reflectometry (TDR), ground penetrating radar (GPR) and electrical resistivity tomography (ERT) were experimentally tested for water leak detection in underground pipes. Each technique was employed in three experimental conditions (one laboratory or two field experiments), thus covering a limited but significant set of possible practical scenarios. Results show that each of these techniques may represent a useful alternative/addition to the others. Starting from considerations on the obtained experimental results, a thorough analysis on the advantages and drawbacks of the possible adoption of these techniques for leak detection in underground pipes is provided. (C) 2013 Elsevier Ltd. All rights reserved.

This paper is focused on the presentation and discussion of an object oriented approach, applied to the Hierapolis (Turkey) site, to automatically detect the subtle features linked to buried archaeological remains. The data processing is applied twice: (i) first, globally at the whole image and, (ii) second, at the significant subsets identified by global analysis, in order to refine the previously obtained categorization. Object oriented approaches are usually based on two main steps: i) first the segmentation, ii) then the classification. Herein, we first performed the unsupervised classification step and, then, the segmentation. This choice is given by the specificity of archaeological issue, in particular: (i) the subtle features/targets to be identified are partially or totally unknown and characterized by a very small spectral separability from the background, and therefore (ii) the discrimination between archaeological class and substrates likely suffers significant confusion. To cope with these issues, the first step is based on an unsupervised classification, which provides a first 'rough' categorization of pixels; the second step, based on the segmentation, enables us to extract the geometric shape, and, in turn, to only categorize as archaeological class those pixels belonging to geometrically (rectangular and linear) shaped clusters. Outputs from this classification identify rectangular and linear features of archaeological interest whose size suggested that they may be a farm and some sectors of an aqueduct, respectively. Results from satellite based analysis were successfully evaluated by georadar and geomagnetic prospection along with field survey. From georadar and geomagnetic prospection we were able i) to confirm the presence of buried remains and ii) to detail and characterize these archaeological features at the subsoil level as well as to define the local stratigraphy. From field survey we dated the detected buried remains to a period spanning from Imperial Roman to early Byzantine historical times.

In this paper, we deal with the problem of two-dimensional electromagnetic linear inverse scattering from dielectric and magnetic anomalies buried in a half-space. First, the formulation of the exact model of the electromagnetic scattering is given. Then, the problem is faced under a simplified model thus arising a linear inverse problem that is solved by resorting to the well assessed singular value decomposition tool. The reliability of the solution procedure is tested with synthetic data achieved by a finite-difference time-domain code. While the presented linear inverse scattering algorithm is able to detect and localize the targets with a good accuracy, it is not able to identify the electromagnetic nature of the targets in terms or dielectric or magnetic properties. © 2010 European Association of Geoscientists & Engineers.

Il Ground Penetrating Radar (GPR) è uno strumento basato sull'impiego di onde elettromagnetiche atto a sondare in maniera non invasiva il sottosuolo oppure l'interno di murature o manufatti di estese dimensioni, alla -ricerca di sottoservizi, reperti archeologici, mine inesplose o anche semplicemente fratture, stratificazioni,- depositi d'acqua. Le applicazioni sono quindi'. molte !ici e si è sviluppata negli anni una vasta letteratura scientifica sia sulle possibilità d'uso, che sull'elaborazione dei dati e sull'implementazione di nuovi sistemi GPR ed antenne [1-5]. In tale ambito, il brevetto riguarda l'ambito dei sistemi GPR Stepped Frequency (SF­GPR), che, differentemente dagli usuali sistemi "impulsati", trasmettono una sequenza di toni sinusoidali invece di un impulso; pertanto l'impulso irradiato viene sintetizzato numericamente come una sovrapposizione dei toni sinusoidali irradiati. I vantaggi -dei sistemi Stepped Frequency rispetto ai più classici GPR "impulsati", sono ampiamente descritti in letteratura [6-8].