Generalised noise cancellation method for wave estimation by HF surface wave radar

High frequency (HF) surface wave radar (HFSWR) has been demonstrated, in many experiments and papers, to be a powerful tool for sea-state detection. However, the availability and accuracy of the HFSWR measurements are limited by various unwanted clutter and interferences (collectively called `noise´) that contaminate the radar received signals, especially for wave estimation. This study extends the image recognition, segmentation and subspace projection method for removing the radio frequency interference developed in the previous study, to the mitigation of more general types of noise. Applications of this generalised method are presented. The results show that the noise can be largely removed regardless of their correlation in Doppler or range, their size in the range-Doppler domain and whether they are homogeneous or inhomogeneous. The effectiveness of all these approaches is validated by using data obtained with the Pisces HF radar, which is a high-performance radar developed for long-range wave measurement, operating in the lower half of the HF band (5-10-MHz).