Performance of the Polar Fourier transform for ocean wave spectrum estimation from marine radar

Scan conversion, as a re-sampling process, is expected to add non-wave components to the wave spectrum. Resampling processes involve applying a low-pass filter to retrieve the original image followed by sampling on the new Cartesian grid. Scan conversion is necessary for ocean wave spectrum estimation using the Cartesian Fourier Transform (CFT). The Polar Fourier Transform (PFT) was originally proposed to avoid this intermediate stage and apply the transformation directly on the radar native form. In this paper, which incorporates field data, the PFT performance in estimating the wave spectrum is tested and compared to results from the CFT. Results show that the PFT outperforms the CFT at lower threshold values. This may imply that part of the noise added to the spectrum is due to the scan conversion process.