Performance of a 400 Mbit/s System over a Line-of-Sight Path

During November 1971, a 400 Mbit/s quadriphase-shift-keyed system was operated at 13.3 and 14.9 GHz over a 22.8-km line-of-sight path. This path was chosen because of its high incidence of meteorological conditions favorable to anomalous propagation. Performance of the system during fading periods is reported here. Additional information from extensive meteorological measurements near midpath is presented to identify the source of the fading. The dual frequency measurements for spaced receiving antennas indicate that diversity reception, properly implemented, would have provided an effective fading remedy.