Experimental results from a 70 Mbit/s-16 QAM 229 km oversea radio link in Italy

The paper reports the experimental results obtained during a first trial period, September 1992 to July 1993, for a digital radio-relay link over the Mediterranean sea between Sardinia and the Continent in Italy. In order to achieve the required level of performance the system configuration was designed to use space (with in-phase maximum power combiners, IPMAP) and frequency diversities with three operating frequencies per direction (early warning driven hitless switching). During the first trial period a new optimized IF combiner prototype was also tested on one channel in order to verify the improving on the space diversity performance. The new combiner uses a new strategy optimized for error probability reduction