Evaluation of GPR Waveforms for a Custom RFSoM-Based Tomography System

Applied Sciences, vol. 16, pp. 6179

Abstract

High-resolution soil moisture monitoring in a lysimeter requires precise Ground-Penetrating Radar (GPR) systems that can provide clean time-domain data for a Full-Waveform Inversion (FWI) algorithm. Using high-speed Radio Frequency System-on-Module (RFSoM) devices provides flexibility in signal generation. To optimize such a system, an appropriate transmit waveform and processing pipeline need to be selected. This paper presents a performance evaluation of three GPR waveforms—impulse, Stepped-Frequency Continuous Wave (SFCW) and non-linear Frequency-Modulated Continuous Wave (FMCW/chirp)—on the same hardware setup. To ensure a fair comparison, all waveforms were tested under an identical total measurement time. Numerical simulations were performed using an electromagnetic model of the system. Physical validation was conducted in an anechoic chamber using a 4 GS/s RFSoM setup and planar elliptical dipole antennas. Simulations showed that both sinewave-based methods provide better signal-to-noise ratios (SNRs) than the impulse GPR, with the non-linear chirp achieving the best results (20.7 dB improvement compared to impulse). Experimental measurements supported these results, showing better SNR across the frequency band for the SFCW and chirp waveforms. Because of its high SNR and simple hardware implementation, the non-linear chirp was identified as the most suitable waveform for this RFSoM-based GPR system.

Authors 6

1. Rati Chkhetia

   Forschungszentrum Jülich · Agricultural University of Georgia

   Affiliation as printed

   Institute for Technology and Engineering (ITE), Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428 Jülich, Germany

   School of Engineering Technology, Agricultural University of Georgia, 240 Davit Aghmashenebeli Alley, 0159 Tbilisi, Georgia

2. Achim Mester

   Forschungszentrum Jülich

   Affiliation as printed

   Institute for Technology and Engineering (ITE), Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428 Jülich, Germany

3. Mathias Bachner

   Forschungszentrum Jülich

   Affiliation as printed

   Institute for Technology and Engineering (ITE), Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428 Jülich, Germany

4. Egon Zimmermann

   Forschungszentrum Jülich

   Affiliation as printed

   Institute for Technology and Engineering (ITE), Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428 Jülich, Germany

5. Zaza Metreveli

   Agricultural University of Georgia

   Affiliation as printed

   School of Engineering Technology, Agricultural University of Georgia, 240 Davit Aghmashenebeli Alley, 0159 Tbilisi, Georgia

6. Ghaleb Natour Aachen Faculty of Mechanical Engineering

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Faculty of Mechanical Engineering (ISF), RWTH Aachen University, Templergraben 55, 52062 Aachen, Germany

   Institute for Technology and Engineering (ITE), Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428 Jülich, Germany