signal processing of GPR

In recent years, geophysical methods have been increasingly applied as a preliminary mapping tool to guide archaeological excavations. Despite the reported growing case histories of geophysical prospections for archaeological purposes, direct comparison between expectations arising from the geophysical results and actual findings is not always systematically performed. A critical comparison between preexcavation geophysical-guided hypotheses and post-excavation archeological evidences is proposed in this work. A test site within the archaeological area of Locri Epizephyrii (Calabria, southern Italy) was chosen for this purpose. An unsurveyed rectangular area (31 × 26 m) was investigated with high-density ground-penetrating radar (GPR) and magnetic profiles. Several anomalous alignments, both compatible and oblique with respect to the orientation of the Greek-Roman city plan, were preliminarly observed in the geophysical results. The use of two different techniques allowed for comparison of anomalous areas, enhancing the likelihood of finding features of significance. Two archaeological soundings were later carried out in the areas showing the most peculiar geophysical anomalies. Several structures revealing the same orientation of the ancient city plan and belonging to at least two different building phases were unearthed from a depth of 15-25 cm below the ground surface. A systematic comparison between geophysical and archeological results was then carried out. In general, walls showing different construction typologies (opus testaceum, opus incertum or opus caementicium) were found to generate similar radar anomalies. Artifacts made with materials similar to the background sandy alluvial deposits were not identified by both geophysical techniques, as in the case of an unearthed channel bank, made of local sandstone blocks. GPR was globally observed to detect buried structures better than the magnetic method, probably due to background geological variables linked to the presence of Fe-rich minerals within the background sediments, generating noisier and scattered magnetic gradient maps.

Ancient buildings in historical town centers can be protected by Cultural Heritage legislation, thus implying that any rehabilitation must respect their main architectural features. These concerns also apply to Modern and Contemporary buildings, in particular if they are important examples of architectural styles from those periods. These extra problems, or motivations, add to the inherent structural delicacy of ancient building restoration that requires detailed knowledge of the building foundations, characteristics and materials, modification history, infrastructure mapping, current pathologies, etc., all relevant information for an informed rehabilitation project. Such knowledge is seldom available before the actual rehabilitation works begin, and the usual invasive preliminary surveys are frequently expensive, time-consuming and likely significantly alter/damage the building's main features or structural integrity. Hence, the current demand for indirect, non-invasive, reliable and high resolution imagery techniques able to produce relevant information at the early stages of a rehabilitation project. The present work demonstrates that Ground Penetrating Radar (GPR or Georadar) surveys can provide a priori knowledge on the structure, construction techniques, materials, history and pathologies in a classified Modern Age building. It is also shown that the use of GPR on these projects requires carefully designed surveys, taking into account the known information, spatial constraints, environmental noise, nature and dimensions of the expected targets and suitable data processing sequences. Thus, if properly applied, GPR produces high-resolution results crucial for sound engineering/architectural interventions aiming to restore and renovate Modern and Contemporary buildings, with (1) focus on the overall quality of the end-result, (2) no damage inflicted to the existing structure, (3) respect of the building's historical coherence and architectural elements and characteristics, that is, its Cultural Heritage value. Most of the findings and applications discussed in this work can be seen as an approximation to model studies, so that, relevant information can be drawn from the different investigated situations. Therefore, owing to the nature and the range of the problems encountered in this case study, it is also expected that the presented GPR data and interpretation will provide important clues and guidance in the planning and investigation of similar projects and problems.

Hidden linear ancient cultural relics were discovered in the alluvial plain of Eastern Henan province (China) using historical archive of aerial photographs and further confirmed by regional features, historical documents and recent archaeological progress. The discovered relics included large-scale man-made ditches, canals and dock relics in Shangqiu and circular moat relics in Luyi. According to historical documents and archaeological researches, we discussed the cultural types and natures of the relics discovered by remote sensing images. On this basis, more pertinent and operable interpretation marks were proposed focusing on hidden linear ancient cultural relics in the alluvial plain. To improve the interpretation of the traditional crop, soil and shadow marks, we also included indexes of scale, continuity, shape and clustering. Our research highlights the macroscopic and spectrographic observation capability of remote sensing in discovering large-scale, massive, surface distribution of ancient cultural relics. In the test area, the solution of image interpretation was proposed through a combined feature identification of scale, continuity, shape and clustering. The derived thematic map demonstrated that the proposed solution is effective for discovering ancient remains in the alluvial plain of eastern Henan, China.

Existing ground penetrating radars (GPR) arc limitcd in their 3-D resolution. For the detection of buried land-mines, their performancc is also seriously rcstrictcd by 'cluttcr'. Rcccnt work by the authors has conccntrated on removing these limitations by employing multi-static synthetic focusing from a 2-D real aperture. This contribution presents this novel concept, describes the proposed implementation, examines the influence of clutter and of various ground features on the system's performance, and discusses such practicalities as digitisation and timesharing of a single transmitter and receiver. Experimental results from a variety of scenarios are presented.

The existence of hidden chambers and corridors adjacent to Tutankhamun's tomb (code name KV62) has been long debated. In 2015 it was suggested that these chambers may host the as yet undiscovered burial of Nefertiti. In order to test this hypothesis, two Ground Penetrating Radar (GPR) surveys, conducted in 2015 and 2016 from inside KV62, were carried out, but gave contradictory results. To solve these uncertainties and obtain a more confident and conclusive response, a third GPR survey was conducted by our team in February 2018. The results of this third radar scan are reported in this article. Three GPR systems with multiple frequency bands (from 150 MHz to 3000 MHz) and very dense spatial sampling were adopted. After careful data processing, no evidence of marked discontinuities due to the passage from natural rock to artificial blocking walls were found in the radargrams. It is therefore concluded that there are no hidden chambers immediately adjacent to the Tomb of Tutankhamun.

A regression model is developed in order to estimate in real time the signal to clutter ratio (SCR) for landmine detection using ground penetrating radar (GPR). Artificial neural networks (ANN) are employed in order to express SCR with respect to the soil's properties, the depth of the target and the central frequency of the pulse. The SCR is

Existing ground penetrating radars (GPR) are limited in their 3-D resolution. For the detection of buried land-mines, their performance is also seriously restricted by `clutter'. Previous work by the authors has concentrated on removing these limitations by employing multi-static synthetic focusing from a 2-D real aperture. This contribution presents this novel concept, describes the proposed implementation, examines the influence of clutter and of various ground features on the system's performance, and discusses such practicalities as digitisation and time-sharing of a single transmitter and receiver. Experimental results from a variety of scenarios are presented

This paper describes the technology of impulse radar and provides examples of how this class of radar system is finding use in a wide variety of civil and military applications. With the reduction in the defence budgets of many governments there has been a shift in the emphasis on radar development to dual-use technology systems that can offer improved performance, in terms of range resolution, imaging and target identification. Impulse radar technology offers a special capability and terms of the ideal radar ambiguity function the impulse radar can exhibit a near optimum response.

The emphasis of this paper is on the applications of high resolution, impulse radar such as airborne terrain profiling, law enforcement, forensic applications, ground probing applications as well as some military applications such as non-co-operative target detection, mine detection, vehicles concealed in vegetation canopy and high resolution detection of targets in high clutter environments.

This paper is structured into three main subject areas.  The first covers the principles that are relevant to the transient waveforms.  The second introduces suitable radar components such as antennas, signal sources, receivers and algorithms for the processing of impulse waveforms.  The third describes some of the variety of applications of impulse radar technology.
IMPULSE RADAR

Iraq is one of the countries that contain many important archaeological sites and manifestations of varied cultural heritage belonging to ancient civilizations. Several archaeological sites and cultural heritage are disappeared as a result of neglect, climate influences and manufactured interventions. In this study, two different radar data were used to image the subsurface with different scales, namely synthetic aperture radar (SAR) image and ground penetrating radar (GPR) data. SAR image was used to extract information regarding potential archaeological remains in Ukhaidir site, southwest of Karbala city. ALOS PALSAR (L-band) image was used to identify and detect the ground anomalies due to the presence of near-surface archaeological structures. Advanced image processing and classification were applied depending on the intensity bands (HH and HV) including texture analysis by application of the Gray Level Co-occurrence Matrices (GLCM) and Principal Component Analysis (PCA) to nominate potential archaeological sites. The results led to identifying 15 sites, eight of them were excluded because they were not covered and clearly visible in the recent high-resolution image and in the field observation, which appears as hills containing scattered stone remains and brick walls. Seven sites (namely P1 to P7) nominated as potential archaeological remains, which were completely covered with loose sand, and its areas are ranging between 873-3774 km2 approximately. Potentially, they might be represented remains of structures for dwelling house or rooms were used by communities living near the fortress.
2D GPR survey were conducted at two sites (sites A and B) near the fortress using a 250 MHz shielded antenna to verify the results of ALOS imagery and historical information, and to characterize and depict the potential subsurface of the buried objects. Site A was in front of the fortress by a few meters included two parallel profiles with a distance of five meters separates between the profiles and 100 m length of each profile. While site B (Site P2) located about 155 m northeast, the fortress included nine parallel GPR profiles with 42.5 m length of each profile and one-meter distance between the profiles, which already covered an area of 8 x 42.5 m (340 m2).
The results of 2D GPR profiles in site A showed four anomalies in the shallow part caused by energy attenuation. Three of them are probably associated with demolished walls of archaeological structures. While the greater anomalies probably associated with Karez (water canal). The results of 2D GPR profiles in site B revealed a number of anomalies interpreted as demolished walls appeared on shallow depths begin approximately 0.15 to 0.3 m below surface, continue down to various depths, and have a width ranging from 0.5-5 m. One of the important anomalies that have been distinguished is the fence (external wall) at a depth of about 0.2 m and around 7 m width.
GPR attribute analysis were used including the instantaneous phase, RMS amplitude, and sweetness attributes to improve the interpretation and achieve the best results. The results led to the identification of a number of anomalies; six were interpreted to be ancient walls, while the others were associated with Karez and fence. RMS amplitude and sweetness attributes successfully determined the boundaries and the horizontal continuity of the ancient walls, but RMS amplitude was more accurate. While the instantaneous phase highlighted the high contrast features of the buried structures and failed to specify the targets that have an angle equal or close to the soil phase angle. The anomalies in the site A appeared with high amplitudes than the anomalies of site B. This is due to the expected archaeological structures in the site A probably constructed from stone, while the structures of site B was built with clay brick.

ABSTRACT This paper reports on a research programme, started recently under DERA sponsorship, on applying synthetic focusing to an oblong horizontal stand-off array, where all the voxels in a vertical slice underneath the centre-line of the array are synthesised electronically, with the third dimension provided by the search vehicle's forward movement. This should permit a very high search rate for buried mines, in a wide range of ground conditions

Existing ground penetrating radars (GPR) arc limitcd in their 3-D resolution. For the detection of buried land-mines, their performancc is also seriously rcstrictcd by 'cluttcr'. Rcccnt work by the authors has conccntrated on removing these limitations by employing multi-static synthetic focusing from a 2-D real aperture. This contribution presents this novel concept, describes the proposed implementation, examines the influence of clutter and of various ground features on the system's performance, and discusses such practicalities as digitisation and timesharing of a single transmitter and receiver. Experimental results from a variety of scenarios are presented.

ABSTRACT Sequential transmission from the elements of a 2D array, with parallel reception and recording by all, permits major economies in transmitted and irradiating power, and provides significant novel processing options for much improved performance in the face of noise or clutter