HF spectral occupancy and frequency planning

The paper gives measurements of spectral occupancy for each ITU-defined user allocation, across the whole HF spectrum. Such measurements are being made currently during stable ionospheric conditions about midday and midnight, at the times of the winter and summer solstice, over a range of sunspot numbers. An application is given in which the occupancy results for a particular service (fixed in this case), are plotted as contours for direct comparison with the conventional OWF predictions. Thus it is possible to choose a frequency based on expected occupancy, as well as on predicted signal/atmospheric noise. The frequency choice for a particular 1500 km link is considered, when it appears beneficial to operate below the predicted OWF during daytime.