How does VOACAP differ from IONCAP?
Minor changes were made to the logic to correct for errors which could occur if only one mode was found, the mode was above-the-MUF and the path had 3 or more hops. Signal power values in the working bands predicted by VOACAP differ from IONCAP by more than 3 dB in only 1.5% of the cases. Very large differences can be found at frequencies above-the-MUF and below the LUF. The LUF and the MUF are the limiting frequencies which define the coverage footprint. The changes made to VOACAP are believed to improve its ability to predict area coverage. No changes were made to the subroutine in IONCAP that computes the actual value of the maximum usable frequency for the lowest order mode. The values of the system parameters (i.e. signal power, reliability, etc.) may be different. A math error in the formula that is used to calculate Reliability and Required Power Gain was corrected. This change makes VOACAP less optimistic than IONCAP by about 2 to 4 dB. A smoothing function was added as a trans
