RADIO TRANSMITTER-RECEIVED INCLUDING MEANS FOR AUTOMATICALLY ADJUSTING THE TRANSMISSION LEVEL

A radio transmitter-receiver including means for automatically adjusting the transmission level so as to bring the reception level in an associated transmitter-receiver receiving such transmission into a range limited at a lower end by a reference reception level by means of an attenuator providing a stepped variable attenuation level and controlled by a signal frequency received from the associated transmitter-receiver; and means for transmitting a signal frequency selected from a set of such frequencies in accordance with the level at which a transmission from the associated transmitter-receiver is received by means of a selector device comprising a set of threshold circuits corresponding to thresholds between said reference reception level and a saturation level limiting the range at an upper end.