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@ARTICLE{Steinbeck:1008407,
      author       = {Steinbeck, Leon and Mester, Achim and Zimmermann, Egon and
                      Klotzsche, Anja and Van Waasen, Stefan},
      title        = {{C}alibration of a {S}tationary {M}ultichannel {GPR}
                      {M}onitoring {S}ystem {U}sing {I}nternal {R}eflection
                      {M}easurements},
      journal      = {IEEE transactions on geoscience and remote sensing},
      volume       = {61},
      issn         = {0018-9413},
      address      = {New York, NY},
      publisher    = {IEEE},
      reportid     = {FZJ-2023-02332},
      pages        = {1 - 10},
      year         = {2023},
      abstract     = {Advanced and extensive processing of ground-penetrating
                      radar (GPR) data, for example, needed for full-waveform
                      inversion approaches, requires a reliable temporal
                      calibration of the system. Usually, the calibration of GPR
                      systems is performed with a known medium between the
                      transmitting and receiving antennas. Thereby, the observed
                      time difference between the expected and measured signal
                      arrival times, termed as time-zero, can be accounted for as
                      a system-specific time delay. For measurement configurations
                      where the antennas are permanently positioned around an
                      object for monitoring purposes, time-consuming additional
                      measurements where parts of the system need to be
                      deinstalled would be required. This is not feasible for the
                      proposed system. Therefore, novel calibration methods for
                      such stationary monitoring systems are required to capture
                      the temporal drift of time-zero. In this article, we present
                      a novel calibration approach that uses internal signal
                      reflections in the measurement system to derive the
                      system-specific time delay without the necessity of knowing
                      the medium between the antennas. We demonstrate that
                      parasitic reflection and coupling signals can be used for
                      accurate in situ calibrations. The presented approach is
                      capable of identifying and correcting for the differences in
                      hardware fabrication, while also correcting the temporal
                      changes in time-zero during experiments. The presented
                      approach is able to reduce the error in time-zero to below
                      25 ps, enabling high-resolution soil research. The presented
                      approach is characterized by requiring no additional
                      calibration setups or measurements since all the necessary
                      data can be acquired during the original soil measurement.},
      cin          = {ZEA-2 / IBG-3},
      ddc          = {550},
      cid          = {I:(DE-Juel1)ZEA-2-20090406 / I:(DE-Juel1)IBG-3-20101118},
      pnm          = {2173 - Agro-biogeosystems: controls, feedbacks and impact
                      (POF4-217)},
      pid          = {G:(DE-HGF)POF4-2173},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:001022035900022},
      doi          = {10.1109/TGRS.2023.3275191},
      url          = {https://juser.fz-juelich.de/record/1008407},
}