Design of optimum filter for blend of GPS height and heave

Precise determination of transducer instantaneous height of multibeam bathymetric system (MBS) is a very important work in fulfilling the transformation from the MBS sounding data to the underwater topographic height. The blend of GPS height and heave can get accurately the solution. But it is a key to design an optimum filter for implementing the blend. In this paper, we study in detail the method of designing optimum filter for the blend. Firstly, we analyze the frequency-spectrum characters of GPS height signal, heave signal and tidal level. Secondly, we choose fast Fourier transform (FFT) as an optimization filter design method for the extraction and blend of the valid signals. Thirdly, by analyzing the frequency-band distributions of GPS height signal and heave signal, we give out the appropriate cut-off frequency as 1/10 Hz in the signal blend. Based on above research, we blend the low-frequency signal from GPS height and the high-frequency signal from heave. Finally, the research was tested and proved by an actual project. An underwater topographic accuracy better than 10 centimeters was achieved by the research with MBS.