Low-cost orientation and positioning method for ocean communication experiments

A low-cost experimental procedure is proposed for measuring the orientation and positioning of an underwater platform with respect to surface platforms using an Inertial Measurement Unit (IMU), a depth sensor, and one or two Global Positioning System (GPS) receivers. The underwater platform is equipped with the IMU and depth sensor, while the surface platform is equipped with a GPS receiver as a rover. The second GPS receiver is mounted on a fixed location as a base station within 10 km of the mobile rover. The IMU and GPS measurements are fused after the experiment to compute the surface platform locations relative to the underwater platform. Four GPS location estimation methods are considered, including the Post-Processing Kinematic, Canadian Spatial Reference System (CSRS) Precision Point Positioning (PPP), Satellite-Based Augmentation System (SBAS), and standalone non-correction method. Errors of the IMU sensor and four GPS methods are analyzed and tested in field experiments. The field test results show that the PPK method is required to achieve azimuth and elevation errors within 1°–2°.