A frequency averaging method to improve sea-state measurements with a HF skywave radar

A frequency averaging method which can improve the quality of averaged spectra of HF signals scattered by the sea is described. The method is compared to the classical single frequency pulse-radar. Using the skywave radar of Valensole, the statistical independence of signals scattered by the sea at close frequencies is experimentally verified. Spectra of signals reflected by an ionospheric layer are presented to illustrate the method. The possibility of further reducing interference by introducing the method in frequency modulated continuous wave (FMCW) systems is discussed.