Radio Communication with Moving Trains

The radiotelegraphic researches carried on under the auspices of the Union Pacific Railroad are described. A radio "danger" signaling system was first worked; and while operative, did not give the extreme reliability required by such systems. A radio controlled car is then described. A series of experiments with arc radiophone equipment are considered. Their applications to inter-car wire telephone communication and train-to-station radiophone communication are given in detail. The necessary fixed stations are also described. The experimental radiotelegraphic car laboratory is then described, together with the antennas, ground, engine, and transmitter thereof. Finally, receiving sets and a telephone relay amplifier (intended to facilitate telegraphone or dictaphone recording of signals) are considered.