Ground Penetrating Radar
Pulsed and stepped-frequency systems are the two most widely used categories of ground penetrating radar (GPR) systems. They are based on ideas and principles dating back to the first half of the twentieth century . According to , the first GPR technology patent was registered in 1910 and regarded a system working in the frequency domain, whereas the first pulsed system was patented in 1926, only. Nonetheless, the commercial development of GPR systems started after the Second World War (which gave a substantial input to the development of radar technology) and regarded pulsed systems, first; subsequently, stepped-frequency systems were commercialised, too. In particular, while pulsed systems were already commercialised in the sixties , the first experiments with commercial stepped-frequency systems date back to the seventies .
The debate on which system is best is still going on today [4, 5]. Stepped frequency systems are claimed to be more performant in terms of dynamic range and signal-to-noise ratio . On the other hand, they present the problem that the receiver needs to have the same dynamic range as the transmitted signal, in order not to saturate when receiving the direct wave. Consequently, stepped-frequency technology is more complex, and this easily drives towards more expensive systems. However, the realization costs of pulsed and stepped frequency systems become similar for GPR systems with antenna arrays . Probably, this is one of the main reasons why most commercial stepped-frequency systems are nowadays equipped with an array of antennas .
Although the majority of GPR systems currently are pulsed systems, we do not yet know in an absolute sense what is the best technology between pulsed and stepped frequency. Probably the answer to this question depends on the application. For example, according to  stepped-frequency systems are more promising for some high-frequency applications, such as demining.
The possibility to reconfigure hardware and software parameters during prospecting has been lately introduced for stepped-frequency systems . In particular, an innovative reconfigurable stepped-frequency GPR prototype [10, 11] was implemented within the A.I.Te.C.H. research project . To the best of my knowledge, pulsed system with analogous reconfigurable features do not yet exist. Until recently, the data recorded by the reconfigurable stepped-frequency GPR prototype were not visible in real time: they could be viewed during post-processing, only. Real-time data visualization is obviously an essential feature, which allows, e.g., immediately identifying the presence of anomalies in the area under test, so that a localized excavation can be executed, or further measurements can be made; it also allows checking the correct functioning of the system in the field.
This paper summarizes the work carried out during my Master thesis in Computer Engineering, at the International Telematic University Uninettuno (Rome, Italy), in 2018, under the supervision of Dr Raffaele Persico (National Research Council of Italy, CNR, Lecce, Italy). My thesis was focused on developing new procedures to be integrated in the acquisition software of the above-mentioned reconfigurable stepped-frequency GPR prototype, in order to allow real-time data visualization. In Section 2, the prototypal reconfigurable GPR system and its original acquisition software are shortly described. In Section 3, the implementation of an improved version of the software is presented, with a main focus on the procedures for real-time data visualization. Conclusions are drawn in Section 4.
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Unrestricted use, distribution, and reproduction in any medium of this article is permitted, provided the original article is properly cited. Please cite this article as follows: F. Brigatti, "Real-time visualization of the data gathered by a reconfigurable stepped-frequency GPR system," Ground Penetrating Radar, Volume 2, Issue 1, Article ID GPR-2-1-3, March 2019, pp. 51-66, doi.org/10.26376/GPR2019003.
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