Sea surface wind speed estimation based on GNSS signal measurements

In this paper we investigate near sea surface wind speed estimation using GNSS (Global Navigation Satellite System) signals. A low-altitude airborne experiment was conducted recently using a UNSW-owned light aircraft over the coast of Sydney. Both direct and reflected signals were captured via a zenith-looking antenna and a nadir-looking antenna respectively. The logged IF data bits were processed to generate delay waveforms and delay-Doppler waveforms. Using the measured waveforms and the theoretical ones, the wind speed can be estimated through waveform fitting. The processed waveforms associated with eight satellites were employed to estimate the wind speed. A four-step method is proposed to perform the waveform fitting. The results show that similar estimation accuracy can be achieved using signals transmitted from satellites with low or high elevation angles. It is demonstrated that the estimation accuracy of the wind speed is around 1 m/s. Further the incorrect encoding of some quantized data bits in a software receiver is investigated.