Are the methods that predict HPF, FOT or LUF in VOACAP reliable to use?
You have hit one of the problems of software development. We only benchmarked Methods 13, 14, 15, 20, 21, 22,and 25. When we first started debugging IONCAP we found that changing the Method could result in different predictions. So we concentrated on the above methods and did extensive testing to assure consistency in the predictions. There are some real logic problems when using terms such as HPF, MUF, FOT and LUF and the IONCAP/VOACAP prediction program. Because IONCAP has an above-the-MUF model, it is possible to have sufficient system power gain to have reliabilities of 90% or higher at frequencies above the MUF. Thus, the FOT may be above the MUF. Also since IONCAP is a quasi-ray trace model, there may be frequencies that just plain won’t propagate between points A and B. For example, one can have a frequency gap between the LUF of the 1F2 and the MUF of the 2F2. Higher frequencies work just fine via the 1F2 mode and lower frequencies are good via the 2F2 mode. But in that frequen
