Research On Wave Measurement Technology Based On The GNSS Buoy Doppler Velocity

As a modern ocean observation instrument,ocean buoy can realize the automatic collection and safe transmission of observation data through remote radio control.It has the ability to collect marine environment data in a stable and reliable manner all day and all time,which provides an important reference to the multi-source stereo monitoring network of key sea areas such as the key sea passage,etc.With the rapid development of GNSS satellite navigation and positioning technology,GNSS buoys have emerged as a new type of low-cost marine measuring instruments.Therefore,a method of obtaining wave parameters based on the ocean wave spectrum by using the GNSS velocity was put forward.And the effectiveness of GNSS buoy wave measurement was proved through the marine experiments.The main content and results are as follows:(1)Based on the effects of various errors in GNSS velocity measurement,the measurement accuracy and applicable conditions of three GNSS velocity models:position difference,original Doppler,out Doppler velocity were compared.In the low dynamic condition,the measurement accuracy of PPK position difference and the single-point out Doppler velocity are higher,and which is better than 1cm/s,while the single-point original Doppler velocity measurement accuracy is poor due to the U-direction velocity error Up to 1dm/s.The accuracy of position differential velocity measurement is more affected by position accuracy than the other two methods,while the original Doppler is easily affected by the noise of the GNSS receiver.The out Doppler is essentially derived by the difference of carrier phase between adjacent epochs,so the observation accuracy is affected by the sampling frequency.(2)An adaptive robust Kalman filter velocity measurement algorithm is proposed.The algorithm uses PDOP and the number of epoch satellite observations as judgment conditions,and divides the velocity calculation scheme into three situations to discuss.Among them,the robust equivalent weight model selects the IGGIII robust model,and the adaptive weight selects the single-factor three-stage adaptive model.The filtering method is evaluated from both static and dynamic measurements.When the state of the moving target changes,the Kalman filter solution result has a smaller trajectory deviation than the least squares solution result,which has a better effect in controlling the abnormal disturbance of the carrier and improving the filtering accuracy.(3)On the basis of the existing research,the current commonly used methods of wave power spectrum estimation and direction spectrum estimation were compared from the aspects of spectrum reproducibility and effectiveness.For the wave power spectrum,the estimation results of classic spectrum analysis and modern spectrum analysis are affected by the parameters of the spectrum estimation method itself,the selection of parameters such as the length and frequency of the sampling process.For the estimation of the wave direction spectrum,the Baycsian method has the best accuracy at present,and the extended maximum entropy buoy algorithm is better than the Bayesian buoy algorithm,but the calculation efficiency is much better than the Bayesian method.(4)A method for observing ocean waves based on GNSS buoy Doppler velocity analysis of ocean wave direction spectrum and power spectrum was improved.A Burg algorithm based on the Autoregressive model is used to analyze the wave power spectrum to obtain the average wave height,average period and other parameters.For ocean wave direction spectrum analysis,the extended maximum entropy buoy algorithm is used to perform direction spectrum analysis on the velocity sequences.The co-testing experiment between the GNSS buoy with the Datawell buoy proved that GNSS not only has high-precision navigation and positioning functions,but also could be used for wave observation and ocean forecasting,which provides a certain reference for the development of low-cost and high-precision GNSS buoys.