Digital recording and short-term prediction of oblique ionospheric propagation

Synchronized oblique step-frequency ionosphere sounding are electrically recorded on punched paper tape without the intervening medium of photographic film. The resulting data are then automatically analyzed to yield statistics on the MOF, LOF, and MPF (a frequency below which multipath exceeds a pre-set limit). The MOF time autocorrelation decays smoothly to 0.87 in 9 minutes and to 0.5 in 65 minutes with minor maxima during the day-night transition periods. The MOF standard deviation between data observed on different days is higher daring the day than at night, and is approximately equal to 0.17 times the corresponding MOF mean value. The electrically analyzed innograms are processed in a manner simulating real time prediction of the above quantities, and their variances. The observed reduction of MOF variance is 0.54 at a prediction lead of 10 minutes, rising to 0.89 at 60 minutes, and is within 5 percent of the limiting values determined by the autocorrelation of the data. A technique for applying the basic propagation predictions to real time frequency management is simulated on a large computer, and reduced to practice on a small sounder accessory computer, with encouraging results.