Simultaneous Sending and Receiving

A system of simultaneous reception and transmission for radio telephony is described, together with the reasons for its use. It involves transferring the received speech (from a separate receiving antenna at some distance from the transmitting antenna) to the subscriber's line, and transferring speech originating at the subscriber's station to the radiophone transmitter. Another type of duplex radio communication is considered, this being based on nearby receiving and transmitting antennas so arranged with their associated apparatus that the receiver and transmitter are in conjugate branches of a Wheatstone bridge. The wiring of the bridge receiver is given and the apparatus shown. A so-called "barrage receiver" is then described. This is a highly directional combination of aperiodic antennas, with unilateral directional characteristic. When two aperiodic antennas are used, the phase difference of the received currents produced in them depends on the direction of the incoming signals. By phase shifting devices and differential coupling to a common receiver, the signals from any given direction can be balanced out. The wiring and apparatus and its functioning are described.