A Low-Cost GPS-Based Wave Height and Direction Sensor for Marine Safety

Masatoshi Harigae, Isao Yamaguchi, Tokio Kasai, Hirotaka Igawa, Hiroto Nakanishi, Takahiro Murayama, Yasunori Iwanaka and Hirotaka Suko

Abstract:	Predicting the development, decay and propagation of ocean waves is essential to allow maritime operations to be carried out safely and economically. A low cost wave height and direction sensor that can be deployed in the open sea is expected to improve the accuracy of wave prediction. We propose a new method for measuring wave height and direction by installing a point-positioning GPS receiver on a buoy placed in the open sea. The essential idea of measuring wave height with centimeter accuracy depends on the fact that the most of the spectrum of GPS point-positioning error exists in the frequency domain below 0.01 Hz, but the frequency spectrum of ocean waves is in a separate band at around 0.1 Hz. Therefore, a sophisticated high-pass filter can extract the movements of a GPS equipped buoy excited by ocean waves with minimum effect of GPS point-positioning error. The three-dimensional GPS positioning data also enables us to measure wave direction. Our proposed system has been already adopted by the Japan Meteorological Agency as the world’s first GPS-based wave height and direction measuring system. This paper presents the concept of the point-positioning GPS-based wave sensor, the algorithms for filtering and extracting wave data, and the results of field trials carried out in the open sea.
Published in:	Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004) September 21 - 24, 2004 Long Beach Convention Center Long Beach, CA
Pages:	1234 - 1245
Cite this article:	Harigae, Masatoshi, Yamaguchi, Isao, Kasai, Tokio, Igawa, Hirotaka, Nakanishi, Hiroto, Murayama, Takahiro, Iwanaka, Yasunori, Suko, Hirotaka, "A Low-Cost GPS-Based Wave Height and Direction Sensor for Marine Safety," Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004), Long Beach, CA, September 2004, pp. 1234-1245.
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