Robert W. Hubbard

Abstract: This report describes an experiment conducted over a LOS microwave link off the coast of southern California. The objective was to determine the effect of known anomalous propagating conditions, caused by persistent temperature inversions in the atmosphere, on a wideband digital:communications system. A channel probe was used to measure the effective impulse response of the transmission channel, and bit–error–rate (BER) measurements were made on the same probe test signal. In addition, a dual receiver was used to investigate the application of angle diversity on the reception of signals in this propagation environment. The results of the experiment indicate that the test link should, if properly configured, support digital transmission at a mission rate on the order of 50 Mb/s. Recommendations for implementing a digital system for the specific link are given in the conclusions.

Keywords: channel characterization; impulse response; angle diversity; digital microwave communications

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