Oceanographic model based azimuth estimator for HF Surface Wave Radar

To resolve the azimuth of a target conventional HF Surface Wave Radars (SWR) either use beamformer or direction finding and suffer from the problem of coarse resolution and inability to resolve small target, respectively. A new approach of combining both of them to achieve higher precision in azimuth estimation for large and small targets is presented. Making use of recently invented detector the presence of a target in a given RD cell is detected by observing the correlation of power along the azimuth axis across neighbouring RD cells. Then using the pre knowledge that target exists in the RD cell a more precise bearing estimation is achieved by oceanographic knowledge based Minimum Mean Square Error (MMSE) Estimator. Since HF SWR signal is dominated by sea clutter which has a non Gaussian probability distribution that changes along the RD map present MMSE Estimators are less suitable. Moreover distribution of received power along Doppler and azimuth depends on velocity of wind. Nearly 250 AIS contacts are compared to the proposed MMSE azimuth estimator and an encouraging agreement is shown. It is also demonstrated that the proposed estimator outperforms the conventional Hamming beamformer.