Study on the fusion of GPS height and heave

摘要

The accuracy of instantaneous height at the reference point (RP) in multibeam surveying has a direct influence on the final results' accuracy. In conventional multibeam surveying, an estimate of the height at the RP provided by the combination of tidal level, squat and heave can not present accurately the actual vertical motion of RP. The conventional approach to vertical referencing is liable to suffer degradation due to both longer period ( > 10 seconds) heave anomalies, and short period motions ( < 15 minutes) not adequately captured by a tide gauge such as dynamic draft variations. An alternate method that can both identify the false heave anomalies and capture the missing part of the vertical motion spectrum would be much better. Since GPS alone lacks the ability to capture the higher frequencies, a blended combination of GPS height and heave would be ideal. A new method is presented in this paper, which blends the high frequency characteristics of a heave sensor with the stable longer period characteristics of a GPS vertical solution. To fuse the two signals effectively, particular attention should be paid to time latency, proper lever arm application and the appropriate choice of filters, etc. Applying this new method, experiments have been done under high dynamic conditions indicating that the new method significantly reduces the vertical error associated with typical inshore multibeam operations.