The purpose in this study is automatic indication on unstable position data from huge data that is observed information received at Advanced Navigation System (The system is operating at Tokyo University of Marine Science and Technology : TUMSAT). In this study, an unstable AIS position is judged by estimated position that is calculated by AIS position. Unstable AIS information of Shioji-Maru are clear by comparison with observed LAN data at Shioji-Maru. The estimated position with the Karman filter using observed AIS information are obtained at every 1 second. If AIS position is include an inferior position, the estimated position will show the meandered trajectory. An observer can judge that there is the inferior position near the meandered trajectory. And the section of meandered trajectory can be indicated automatically by components after Fourier transform on the change of this moving direction of estimated position. The inferior position defined by the observed value on board and estimated position by AIS were compared, and a Fourier components to assess of inferior information were confirmed.
As a result, an inferior AIS information Shioji-Maru observed by Advanced Navigation System was almost indicated automatically by this method.
