PRELIMINARY ITALIAN EXPERIMENTS ON DIGITAL LAND MOBILE RADIO.

Results are presented of research activities in the framework of the European cooperation for a fast definition of a pan-European public land mobile system, operating in the 900 MHz frequency band. Propagation, base-band processing and modulation methods are investigated. As far as propagation is concerned, field strength measurements are presented, showing the impact of local building densities on signal levels, together with man-made noise measurements, performed in different traffic conditions. The characteristics of an experimental modem, capable of operating with any modulation method of the 12PM3 class, at different bit rates, are described and its laboratory and field performance is analyzed. The main characteristics of the speech coders are presented and some considerations are made on the choice of the possible cellular structure.