Spectral occupancy-measurement system and mathematical models

Systematic measurements of HF spectral occupancy have been made since 1982, and mathematical models are being developed and updated as new results become available. The experimental data base has been improved by the establishment of an automatic system for spectral occupancy measurement. In particular, congestion over the entire HF spectrum is measured at least monthly, rather than only at the times of the solstices. It is important to include other parameters in the occupancy model, for example, bandwidth, geographical location and possibly antenna directivity. These problems are under consideration