Ionospheric modelling based on oblique chirp-sounders

Classical ionospheric HF propagation forecasts seem to result in significant differences compared with oblique chirp-plots. The Belgian Ministry of Foreign Affairs uses a centralized HF radio communications system for diplomatic purposes. Chirp-sounders are used to evaluate different main radiopaths before the radio transmissions take place and to correct (and improve) the maximum frequency forecast. The result for the path Brussels-Athens was analyzed during the months of June, July, August and September 1986 from the chirp-sounder-receiver. The results of the first test-month were used to adapt, from a popular algorithm, some parameters giving the MUF value.<>