Measurement capabilities of an HF channel evaluation system

The main characteristics of an HF channel evaluation system (CES) are described. The basic experimental capabilities of the CES are considered. Each mode of operation of the CES is illustrated by examples of the system output obtained on a midlatitude path. The measurements are furthermore interpreted with the help of vertical soundings performed near the midpoint of the path. The modes of operation described comprise: vertical and oblique soundings (measurements of the channel impulse response and the main propagation parameters) and polarization diversity (space diversity can be performed as well). In another mode of operation, the output of the HF receiver is digitized before any signal processing takes place, and recorded for further analysis