Modelling of real-time precision point positioning wave measurements

In order to meet the high-precision wave measurement requirements of missing base stations in sea areas, this paper proposes a wave measurement algorithm based on GNSS Real Time Precision Point Positioning（RT-PPP） and conducts on-site testing on Xiaomai Island, Qingdao. First, the instantaneous sea surface height information of the buoy is obtained based on the real-time precision ephemeris and GNSS observations; then, a high-pass filter is used to separate the low-frequency tide information from the high-frequency signal, and the high-frequency Sea Surface Elevations（SSE） sequence is analyzed spectrally; finally, the effective wave height and wave peak period are counted. In order to analyze the reliability of the algorithm, the obtained wave parameter values are compared with Post Processing Kinematic（PPK） and Precise Point Positioning（PPP）wave measurement algorithms. The results can be obtained that although the RT-PPP positioning accuracy is relatively low and there is a large error in the tide observation, with an average error of 15.8 cm, it hardly affects its accuracy in high frequency wave measurement. the power spectrum obtained by RT-PPP and PPK, PPP is basically the same in the high frequency part and has the same peak value. In the significant wave height calculation, the correlation coefficients of RT-PPP results with PPK and PPP are 0.994 and 0.998, respectively, and the accuracy can reach 3.1 cm; The correlation coefficients of peak period obtained are 0.807 and 0.962, respectively. Therefore, RT-PPP wave measurement model can effectively achieve the wave parameters observation in the ocean far from the base station.