title: Wave measurements using GPS velocity signals.
abstract: This study presents the idea of using GPS-output velocity signals to obtain wave measurement data. The application of the transformation from a velocity spectrum to a displacement spectrum in conjunction with the directional wave spectral theory are the core concepts in this study. Laboratory experiments were conducted to verify the accuracy of the inversed displacement of the surface of the sea. A GPS device was installed on a moored accelerometer buoy to verify the GPS-derived wave parameters. It was determined that loss or drifting of the GPS signal, as well as energy spikes occurring in the low frequency band led to erroneous measurements. Through the application of moving average skill and a process of frequency cut-off to the GPS output velocity, correlations between GPS-derived, and accelerometer buoy-measured significant wave heights and periods were both improved to 0.95. The GPS-derived one-dimensional and directional wave spectra were in agreement with the measurements. Despite the direction verification showing a 10° bias, this exercise still provided useful information with sufficient accuracy for a number of specific purposes. The results presented in this study indicate that using GPS output velocity is a reasonable alternative for the measurement of ocean waves.
authors.affiliation: Department of Marine Environmental Informatics, National Taiwan Ocean University, 2, Beining Rd., Keelung 20224, Taiwan. doong@mail.ntou.edu.tw
authors.forename: Dong-Jiing
authors.initials: DJ
authors.lastname: Doong
authors.forename: Beng-Chun
authors.initials: BC
authors.lastname: Lee
authors.forename: Chia Chuen
authors.initials: CC
authors.lastname: Kao