Transmission techniques for terrestrial flight telephone systems

A preliminary evaluation of the radio transmission performance of an aeronautical digital telephone system with possible application to the terrestrial flight telephone system (TFTS), is presented. Transmission and signaling will be digital within the 1.6 GHz band, using time-division multiple access (TDMA) and time-division multiplexing (TDM) in the air-to-ground and in ground-to-air links, respectively. Many topics must be studied in order to design a spectrum-efficient and toll-quality system. Some of these are addressed, such as propagation and modulation. In particular, first results are provided on the application of the GMSK (Gaussian minimum-shift keying) modulation with coherent demodulation to the aeronautical telephone system, considering the main propagation impairments and the burst-like transmission due to TDMA. As a preliminary result, GMSK turns out to be feasible solution