Improved ship´s navigation accuracy through precise data reconstruction

A high-accuracy post-time navigation data reconstruction technique has been developed for bathymetric survey ships. The ship´s navigation system integrates satellite Loran-C, inertial navigation, Doppler and electromagnetic logs and gyrocompass data. It has been necessary, for some areas, to develop post-time processing algorithms to alleviate position and velocity accuracy degradation arising from infrequent satellite fixes and limited availability of Loran-C coverage. Enhancement was achieved utilizing log velocity data to detect high-frequency inertial navigation Schuler errors. Implementation was achieved by expanding an operational 15-state Kalman smoothing algorithm, incorporating position error measurements only, to a 23-state system which included log velocity measurements