Some measured properties of the ionosphere reflection channel at high frequencies

An HF sounder capable of continuous wave (CW) operation at 800 equally spaced discrete frequencies from 5 to 15 MHz, the hardware of which also allows ranging measurements to be performed, is described. Ranging data that possess periodic spikes which can be used to determine the propagation delay with resolution of up to 10 μs are presented. Based on these data, the dispersive bandwidth is estimated. In some cases the data clearly show the existence of multiple propagation modes. In CW operation the complex channel transfer function of up to six different frequencies was measured, from which a variety of statistics helpful to characterize the channel determined. Some cases are presented. The measured channel characteristics are discussed