3:30 PM - 5:00 PM
[SGD01-P11] Correction method for instrument- and angle-dependent errors in GNSS-A observations
Keywords:GNSS-A, Seafloor geodesy, Marine Acoustics
In GNSS-A data, particularly data from SGO-A operated by the Japan Coast Guard, we have found that the vertical position determination accuracy was larger than the predicted variability from the analysis results and errors. There have been many discussions about the cause, such as environmental disturbances and equipment problems, but recent data analysis has revealed that the main cause is bias caused by reading errors of the communication signal depending on the equipment (sea surface station and seafloor station) and observation timing. This bias has an angular dependence on the equipment. and there is analogy with GNSS (e.g., multipath and PCV correction). The scale of the error is about 7-8 cm in one-way in an environment where 10kHz sound waves propagate at about 1500m/s.
To accurately analyze this problem and develop correction methods, communication and positioning experiments were conducted in a water tank. In an experiment conducted at the Tokyo University Kashiwa IIS Ocean Engineering Basin in October 2022, the tendency of reading errors that were estimated to occur at the actual observation was reproduced. For some of the results, please refer to Ishikawa et al. in the "S-SS12" session and Nagae et al. in the "S-CG52" session.
Although the tendency of reading errors was reproduced in the experiment, it was not certain why reading errors occurred. To correct each acoustic data, it is necessary to separate and identify the cause of the reading error from parts of the transmission and reception.
In this presentation, we will analyze the cause of this reading error from the waveform of hydrophone data measured in the middle of transmission and reception, for the occurrence of reading errors. Hydrophones were mounted on onboard and seafloor stations, and were observing signals immediately before and after transmission from the onshore station and immediately before and after transmission from the seafloor station. In this presentation, we consider the analysis of these hydrophone data and the causes of differences between the equipment, taking into account the sonar structure and elements.
Achnowledgement: This study was supported by ERI JURP 2022-Y-KOBO25 in Earthquake Research Institute, the University of Tokyo, by the University of Tokyo Excellent Young Researcher project, by SECOM science and technology foundation, and by JSPS KAKENHI Grant Number JP21H05200 in Grant-in-Aid for Transformative Research Areas (A) “Science of Slow-to-Fast Earthquakes.”
To accurately analyze this problem and develop correction methods, communication and positioning experiments were conducted in a water tank. In an experiment conducted at the Tokyo University Kashiwa IIS Ocean Engineering Basin in October 2022, the tendency of reading errors that were estimated to occur at the actual observation was reproduced. For some of the results, please refer to Ishikawa et al. in the "S-SS12" session and Nagae et al. in the "S-CG52" session.
Although the tendency of reading errors was reproduced in the experiment, it was not certain why reading errors occurred. To correct each acoustic data, it is necessary to separate and identify the cause of the reading error from parts of the transmission and reception.
In this presentation, we will analyze the cause of this reading error from the waveform of hydrophone data measured in the middle of transmission and reception, for the occurrence of reading errors. Hydrophones were mounted on onboard and seafloor stations, and were observing signals immediately before and after transmission from the onshore station and immediately before and after transmission from the seafloor station. In this presentation, we consider the analysis of these hydrophone data and the causes of differences between the equipment, taking into account the sonar structure and elements.
Achnowledgement: This study was supported by ERI JURP 2022-Y-KOBO25 in Earthquake Research Institute, the University of Tokyo, by the University of Tokyo Excellent Young Researcher project, by SECOM science and technology foundation, and by JSPS KAKENHI Grant Number JP21H05200 in Grant-in-Aid for Transformative Research Areas (A) “Science of Slow-to-Fast Earthquakes.”