11:00 AM - 1:00 PM
[SVC34-P05] A feasibility study for a pillar-coupled seabed GNSS station
Keywords:GNSS, Volcanic ground deformations, Aira Caldera
Positioning tests of the moving and tilting antenna array will be reported. The purposes of the tests are that considering feasibility of kinematic method of GNSS location for a pillar-coupled seabed GNSS station. A pillar-coupled GNSS station has been planned to install in the Kagoshima bay for the purpose of measuring ground deformation in a closer place of known deformation sources in Aira caldera. the structure of the station has to endure exerted forces from environmental penomena, such as tide, wave and winds, through tilting itself. Operation of the station requires a method for reducing tilt of the structure.
Several problems have to be considered for feasible design of the station. the first is stability of the kinematic method through a long period, such as for a year, the second is that confirm velocity response of the GNSS processing method, the third is how to measure and to reduce the tilt of the pillar.
A long period test of the kinematic method was performed with using permanent stations and provided compatible accuracy with that by the static method. Antenna pair method and tiltmeter method were compared in an early phase of the tests. Although tiltmeter method provides over-estimated tilt, the antenna pair method provides more accurate tilt of the antenna pillar under 1D motion on the single axis platform. The confirmation of velocity responsewas tested in the next phase. The kinematic analysis provides flat response over the velocity up to 2 m/s. The third phase of the tests performed on a bi-axis platform with the quad-antennas array in order to confirm tilt-reduction processing created. Quad-antennas array provides stable location, which comprises two antenna pair system. Quad-antennas array is adopted in the final design of the seabed GNSS station. This research is supported by the safety research fund from Nuclear Regulation Authority.
Several problems have to be considered for feasible design of the station. the first is stability of the kinematic method through a long period, such as for a year, the second is that confirm velocity response of the GNSS processing method, the third is how to measure and to reduce the tilt of the pillar.
A long period test of the kinematic method was performed with using permanent stations and provided compatible accuracy with that by the static method. Antenna pair method and tiltmeter method were compared in an early phase of the tests. Although tiltmeter method provides over-estimated tilt, the antenna pair method provides more accurate tilt of the antenna pillar under 1D motion on the single axis platform. The confirmation of velocity responsewas tested in the next phase. The kinematic analysis provides flat response over the velocity up to 2 m/s. The third phase of the tests performed on a bi-axis platform with the quad-antennas array in order to confirm tilt-reduction processing created. Quad-antennas array provides stable location, which comprises two antenna pair system. Quad-antennas array is adopted in the final design of the seabed GNSS station. This research is supported by the safety research fund from Nuclear Regulation Authority.