Abstract: Each station comprises a cavity oscillator microwave transmitter/receiver employed both as transmitter and local oscillator, each secondary station being characterized by the value of its own intermediate frequency. The main station separately receives each of the intermediate frequencies and is modulated by a multiplexed signal formed by the information intended for each of the secondary stations.

Abstract: A demodulation signal results from the sum or difference of two output signals, respectively from two demodulators applied in parallel with the signal for demodulation and in quadrature by a local carrier generator having the same frequency that the one of the received modulated signal.

Abstract: Stations allowing the use of directional antennas for multiple connections between a master station and each one of subordinate stations. The antenna of a master station M rotates uniformly. When it is directed towards a subordinate station S, the informations to be transmitted, compressed to this end, are transmitted bilaterally. The expansion of the compressed information received takes place regularly. If the stations are mobile, the antennas of the stations S are equipped with an acquisition and servosystem keeping it directed towards the station M.