A radio method for synchronizing recording apparatus
T. Parkinson, T.R. Gilliland · Bureau of Standards Journal of Research · 1931
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.