A Radio Method for Synchronizing Recording Apparatus

A method is described for running two radio fading recorders at the same speed when it is necessary to have one of the recorders portable so that it can be moved to various distances from the other. In the work reported each of the recorder drums was propelled by a synchronous motor of the type used for clocks. Since wire connections were not practicable the portable recorder was controlled by a radio transmitter placed at the fixed station. The same 60-cycle source of power used to drive the synchronous motor at the fixed station was used to modulate the transmitter, the signal of which was received at the portable station and amplified sufficiently to drive the synchronous motor there. With the transmitter working on low power it was possible to drive the recorders at the same speed when separated by a distance of 16 km. A method is described for marking the two records simultaneously so that they can be superposed.