The rise and fall movement of a vessel correlates directly to the returning sonar data in marine mapping applications, leading to errors in depth measurement. To compensate for these errors, select SPAN receivers feature the robust heave output option.
The images below show the ocean floor mapped with and without heave compensation. With wave motion eliminated from the data, a much more accurate and coherent image is generated.
Two SPAN Heave Solutions Available
NovAtel® offers real-time and post-processing options for marine application developers.
Real-Time Measurements: SPAN receivers provide accurate, instantaneous and delayed measurements of wave motion under the most difficult marine conditions and vessel dynamics. They offer a full six degrees-of-freedom position and orientation, measuring position, velocity and attitude. The heave filter provides an asynchronous log available at 10 Hz, a synchronous log available up to the IMU data rate and a delayed log up to 10 Hz.
Post-Processed Solution: Inertial Explorer® software from NovAtel's Waypoint® Product Group, post-processes data forward and backward, ensuring the most accurate heave solution.
SPAN (Synchronous Position, Attitude and Navigation) technology brings together two different but complementary technologies: Global Navigation Satellite System (GNSS) positioning and inertial navigation. The absolute accuracy of GNSS positioning and the stability of Inertial Measurement Unit (IMU) gyro and accelerometer measurements, combine to provide an exceptional 3D navigation solution delivering full attitude and orientation.
The SPAN Heave algorithm estimates the short term, vertical displacement of a vessel, relative to the mean sea state caused by waves or swells. This allows a sonar system to compensate for the range errors caused by these effects.