Wave measurements using GPS velocity signals.

Area of Science:

• Oceanography
• Geophysics
• Signal Processing

Background:

• Traditional wave measurement relies on buoys and sensors.
• Accurate ocean wave data is crucial for maritime safety and research.
• Existing methods can be costly and limited in scope.

Purpose of the Study:

• To investigate the feasibility of using Global Positioning System (GPS) velocity signals for ocean wave measurement.
• To validate GPS-derived wave data against accelerometer buoy measurements.
• To assess the accuracy and limitations of GPS-based wave sensing.

Main Methods:

• Utilized GPS-output velocity signals and transformed them into displacement spectra.
• Applied directional wave spectral theory.
• Conducted laboratory experiments and field tests with a GPS-equipped accelerometer buoy.
• Implemented signal processing techniques like moving average and frequency cut-off.

Main Results:

• GPS-derived significant wave heights and periods showed strong correlation (0.95) with buoy measurements after signal processing.
• One-dimensional and directional wave spectra derived from GPS data agreed with measurements.
• Identified signal loss, drifting, and low-frequency energy spikes as sources of error.
• Observed a 10° bias in directional wave verification.

Conclusions:

• GPS velocity signals offer a reasonable and accurate alternative for specific ocean wave measurement applications.
• Signal processing is essential to mitigate errors and improve the reliability of GPS-derived wave data.
• Further refinement could enhance the accuracy of directional wave measurements using GPS.