Real-time visualization of the data gathered by a reconfigurable stepped-frequency GPR system

Filippo Brigatti
2019 Ground Penetrating Radar  
This paper describes recent improvements made to the acquisition software of a reconfigurable stepped-frequency ground penetrating radar (GPR) prototype, to allow real-time data visualization. In particular, real-time data visualization was not yet implemented in the previous version of the acquisition software, although this is a common feature available in all commercial systems. This was a bad problem for the GPR prototype: the possibility to visualize data in real time is obviously of vital
more » ... importance, because it makes it possible for the user to easily identify promising areas in the field, or to recognize an anomalous functioning of the system without wasting a day of work. So far, real-time data visualization was not yet possible because the prototype at hand is equipped with three equivalent couples of antennas that can transmit and receive data simultaneously, which implies a quite large amount of data recorded per second. Nonetheless, by implementing suitable procedures for a more efficient data handling, the problem has been successfully solved and now the prototype is not anymore "blind" in the field. 52 were already commercialised in the sixties [1], the first experiments with commercial stepped-frequency systems date back to the seventies [3] . 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 [4] . 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 [6] . Probably, this is one of the main reasons why most commercial stepped-frequency systems are nowadays equipped with an array of antennas [7] . Although the majority of GPR systems currently are pulsed systems, we do not know in an absolute sense what is the best one between the pulsed and the stepped frequency technology. Probably, the answer to such a question also depends on the application. For example, according to [8] stepped-frequency systems are more promising for some high frequency applications such as demining. The possibility to reconfigure some hardware and software parameters during prospecting has been lately introduced for stepped-frequency systems [9] . In particular, a reconfigurable stepped-frequency system [10, 11] has been implemented within a research project called Aitech [12] . To the best of my knowledge, analogous reconfigurable pulsed systems do not yet exist. Until recently, this reconfigurable stepped-frequency prototype had the problem that data were not visible in real time in the field. They were recorded in the field and could be viewed only during the post-processing. Real time data visualization is obviously an essential feature, which allows, e.g., checking the correct functioning of the system in the field and immediately identifying the presence of anomalies of interest in the area under test, so that a localized excavation can be carried out or further geophysical measurements can be made.
doi:10.26376/gpr2019003 fatcat:rffsi3evzndrtbfhpp2kpebr2u