Real-Time Update of Two Well-Known Models of the Maximum Usable Frequency

For years, models of the high frequency (HF) radiowave propagation environment have been used to provide system design and strategic planning information for various military and civilian systems. However, since most models are based upon averages of a large data base, they are of little value to the user who requires highly accurate tactical HF propagation information in real-time. The lack of this highly accurate real-time tactical capability is an important remaining problem. This paper discusses a simple technique that draws upon currently available models of the MUF which might be made to perform more accurately in real-time after being updated by MOFs from an oblique sounder network. The models discussed are the well known and widely used codes MINIMUF 3.5, resident in the NOSC PROPHET System, and IONCAP. In the limited data shown, both models show reasonable improvement in their estimates of MUF after receiving an update using the MOF obtained from a reference oblique sounder circuit. The verification of this real-time update technique has important implications to many users of the HF band.