Ocean surface current measurements by HF radar under external radio frequency interference

High-frequency (HF) radar systems located at the coast are well-known as a measurement tool for synoptic on-line mapping of ocean surface current fields. Nevertheless, HF radar performance suffers from external radio frequency interference signals generated by other HF-band users. This paper describes a modified signal processing technique in order to reduce the interference impact on radar power spectra. It allows obtaining the Bragg resonant frequencies masked by interference signals and thus to measure the ocean surface current velocities. The measured HF radar data are used to demonstrate the performance of the developed signal processing technique for different operating radar frequencies.