Summary of propagation conditions and digital radio performance across the English Channel

The transmission of digital information in microwave line-of-sight circuits can be easily degraded by multipath effects, particularly in long overwater paths such as the English Channel. The results of a test program designed to investigate the propagation conditions, the multipath parameters, and the performance of a new digital radio over this link are presented. It is shown that the performance of the radio is improved by adaptive equalization techniques used in its design. However, the performance was below expectations at times, and these specific problems are treated. It is concluded that a dynamic aspect, namely, the rate of change of the multipath delay, is one cause for the unexpected degradation