Frequency selection for HF long-haul radiocommunication in emergency situations

Combined use of satellite communications and HF radiocommunication is realized often, where HF radio is applied mostly and only in special cases is expensive satellite communication used. The deficiency in HF radio is that it has limited capacity of operating frequencies. It is shown that approximate values of HF operating long-haul HF radio frequencies can be chosen with use of prognosis of least applicable frequencies.