An empirical model for the probability distribution of the lowest observed frequency
Abstract
A model of the distribution of the lowest observed frequency (LOF) is presented. The frequency spectrum of recorded minutebyminute LOF data was bounded on its lower end by radio noise and ionospheric absorption during the daytime and by lowest sounded frequency at night, and at its upper end by the highest observed frequency path. The Johnson S(B) system of frequency curves was fitted to LOF data using the method of moments. This system was chosen because (1) it represents all bounded distribution systems; (2) its simplicity of calculation makes it adaptable to minicomputer type applications; and (3) the transformation of the variables to the normal system allows use of normal probability algorithms. The four parameters of the distribution were determined as a function of path local time. The results for one path, France to Iceland, for October 1975 are presented. It was found for this data that the model was most accurate during the daytime, where the lowest observed LOF during an hour was above the lowest sounded frequency.
 Publication:

In: Symposium on the Effect of the Ionosphere on Radiowave Systems
 Pub Date:
 1981
 Bibcode:
 1981eirs.sympU....S
 Keywords:

 Atmospheric Models;
 Extremely Low Frequencies;
 Ionospheric Propagation;
 Probability Distribution Functions;
 Radio Signals;
 Computerized Simulation;
 Data Smoothing;
 Minicomputers;
 Noise Intensity;
 Remote Sensing;
 Communications and Radar