Empirical Models Representing the Error in the Predicted MUF (Maximum Usable Frequencies) and Field Strength from HFBC84

摘要

Models of the probability distribution representing the residuals between the observed MOF (Maximum Observed Frequencies) and field strength and the corresponding predicted values from HFBC84, and inosopheric prediction program developed for the broadcast WARC, are presented. A data base of 13,054 hours of oblique sounder MOFs modifiedversion of CCIR Data Base C was used to obtain the residuals in predicted field strength; only the 81 paths for short path propagation were retained. The residuals for these models were fit to the Johnson system of frequency curves. This system of curves consists of three distributions: (1) data that is unbound, called the SU distribution; (2) data that is bound on one end called the SL distribution; and (3) data that is bound on both ends, called SB distribution. Overall for the MUF residuals, it was determined that the data could be represented by a S distribution. Overall for the field strength residuals, a SU distribution fit the data for frequencies below or equal the predicted MUF, and a SB distribution fit the data for frequencies greater than MUF.