A practical method of calculating delay spread from voacap predictions

In this paper, a Monte Carlo method has been applied to calculating the multipath spread of HF signals from VOACAP predictions. This method uses the predicted SNR probability distribution functions rather than just taking the median SNR to provide a probability distribution of multipath spread values. Predictions are compared with measurements over two paths, one at mid-latitudes and the second at sub- auroral latitudes. At mid-latitudes, the predictions are generally consistent with observation at higher frequencies, but underestimate the spread at lower frequencies during the day. For the sub-auroral path, the predicted spreads are higher than those observed at all times of day. The new method will be useful to those planning or operating digitally modulated radio systems in the HF band since these can be adversely affected by multipath spread.