Forecasting and updating HF channel parameters on the basis of oblique chirp sounding

Lowest observed frequency (LOF) and maximum observed frequency (MOF) spatial‐temporal correlation data for midlatitude long‐distance paths are presented. The possibility of improving LOF and MOF forecasting accuracy for links without diagnostic systems by means of linear regression methods and a semiempincal ionospheric model is investigated, and a comparison is made of the effectiveness of providing HF communication frequencies on the basis of long‐term forecasting and real‐time channel evaluation.