Short-term forecasting method of maximum usable frequency for HF communication based on oblique sounder

Based on oblique sounding system, a short-term forecasting method of maximum usable frequency for HF communication was presented. The method include four steps: firstly, maximum usable frequency of oblique sounding circuit was forecasted based on its sounding data; secondly, the critical frequency of sounding path midpoint was determined from the oblique sounding data and its forecast data by using ray-path theory; thirdly, the critical frequency was reconstructed for forecast circuit; in the end, maximum usable frequency for HF communication circuit was given. Using the oblique sounding data during March 2012, the accuracy and practicability of the method was validated. The root-mean-square error of the short-term forecast is 1.56 MHz, and is reduced 0.40MHz contrast to that of the long-term prediction. The research provides the important reference for frequency selection and frequency management of HF communication.