STUDY OF MEASURED AND PREDICTED RELIABILITY OF THE IONOSPHERIC HF COMMUNICATION CHANNEL AT HIGH-LATITUDES

This paper describes observations of the reliability of the ionospheri c HF communication channel within and close to the northern auroral zo ne. Automatic equipment has been developed to measure reliability and virtual reflection height as a function of frequency in an hourly cycl e. Measurements have been made over two propagation paths within Norwa y. The data show diurnal and seasonal variations as well as dependence of the measured parameters on geomagnetic conditions. The observation s have been compared with predictions obtained from the Ionospheric Co mmunication Enhanced Profile Analysis and Circuit Prediction Program ( ICEPAC) prediction code. This code includes a model of the high-latitu de and polar ionospheres and their dependence upon geomagnetic disturb ances. The results of the comparison show that ICEPAC represents an im provement over previous codes but that transmission losses are not pro perly included.