6. LSU HF radiolocation

Single Site Location (SSL) enables the geographic coordinates of an HF transmitter to be determined with a single direction-finding station, using the reflection of waves off the ionospheric layers to provide an estimate of the direction finder-transmitter distance. In addition to azimuth, the direction finder must therefore be able to provide a measurement of the elevation angle Δ (figure 27 ).

Knowledge of the elevation angle enables us to estimate the distance based on known or measured ionospheric parameters along the signal propagation path. The distribution of ionospheric layers, variable in time, place and altitude between 100 and 400 km, is a function of relatively well-controlled parameters such as...