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As a unique technique for the seafloor positioning with centimeter-level precision within the global reference frame, GNSS-A has extended the field of geodesy to the seafloor. Achieving precise positioning with GNSS-A requires mitigating or correcting various errors arising from environmental and instrumental uncertainties. Decades of effort in developing the GNSS-A system have successfully reduced those effects. To address environmental errors, appropriate sound speed field models have been introduced. For instrumental errors—specifically those related to (1) acoustic travel time measurements, (2) the reference sound speed profile, (3) GNSS positioning of the surface platform, (4) attitude measurements using a gyroscope, (5) the premeasured local tie between the GNSS antenna and the transducer (ATD offset), and (6) time synchronization among the loggers—we have quantitatively assessed their impacts and developed correction methods. In particular, errors in the ATD offset (5) can be directly estimated from GNSS-A data. We applied an estimation method for the ATD offset and compared them with the premeasured values. The results suggested the existence of significant biases in the premeasured values for several onboard systems.

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Understanding Biases Due to the Instrumental Errors in GNSS-A Seafloor Positioning

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  • 出版模式：

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  • 发表日期：

    2026年

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  • Shun-ichi Watanabe,
  • Tadashi Ishikawa,
  • Yusuke Yokota,
  • Yuto Nakamura,
  • Koya Nagae

摘要

As a unique technique for the seafloor positioning with centimeter-level precision within the global reference frame, GNSS-A has extended the field of geodesy to the seafloor. Achieving precise positioning with GNSS-A requires mitigating or correcting various errors arising from environmental and instrumental uncertainties. Decades of effort in developing the GNSS-A system have successfully reduced those effects. To address environmental errors, appropriate sound speed field models have been introduced. For instrumental errors—specifically those related to (1) acoustic travel time measurements, (2) the reference sound speed profile, (3) GNSS positioning of the surface platform, (4) attitude measurements using a gyroscope, (5) the premeasured local tie between the GNSS antenna and the transducer (ATD offset), and (6) time synchronization among the loggers—we have quantitatively assessed their impacts and developed correction methods. In particular, errors in the ATD offset (5) can be directly estimated from GNSS-A data. We applied an estimation method for the ATD offset and compared them with the premeasured values. The results suggested the existence of significant biases in the premeasured values for several onboard systems.