High-frequency (HF) surface wave radar systems located at the coast are well-known as a measurement tool for coastal monitoring. Nevertheless, HF radar performance suffers from external radio frequency interference (RFI) signals generated by other HF-band users. This paper describes a way of signal processing in order to reduce the interference impact on radar power spectra and to estimate the Doppler frequencies generated by the resonant backscatter from ocean surface and by moving maritime targets. The measured HF radar data are used to demonstrate the performance of the developed signal processing technique for different radar applications. (4 pages)