Correlation Measurements on an HF Transmission Link

In data transmission over long-haul HF circuits, the signal is subjected to the vagaries of a turbulent ionospheric medium. To permit accurate performance predictions it is necessary to obtain a comprehensive channel description. This paper describes a program designed to achieve two goals. 1) To determine the feasibility of performing an experiment with sufficient accuracy to determine the time-variant medium transfer characteristic. 2) To obtain sample descriptions of these characteristics. The statistical medium descriptions obtained included first-order probability distribution functions of phase and amplitude and the secondorder time-frequency correlation functions. Records of the above medium descriptors obtained over a more extensive testing period will aid in the determination of optimum signaling techniques and in reliable data performance predictions.