A doppler frequency calibration method by ionosphere for skywave OTHR

The RD (Range-Doppler) spectrum of signal received from high frequency OTHR (over-the-horizon radar) consists of two Bragg peaks. However, contaminated by ionosphere, both two Bragg peaks will be shifted. A method based on Kullback-Leibler (KL) divergence and centroid, named Mode-Kullback-Leibler-Centroid (MKLC), is proposed to get a better estimate of the center frequency of RD spectrum. In the real data experiments, the proposed method is capable of achieving better performance with lower RMSE.