Methods of Reducing the Effect of Atmospheric Disturbances

The transmitter sends the dots and dashes on one frequency and the spaces on a slightly different frequency. At the receiver a local frequency is superimposed producing two audio frequencies. The paths of the two audio frequencies are combined differentially so they would oppose if they occurred at the same time; also, they would pull the marking pen in the opposite direction if they occurred at the same time. Since one audio frequency is due to the dots and dashes while the other is due to the spaces, they do not occur at the same time. Since static hasn´t a definite frequency it may produce about the same amount of audio-frequency current in each path, thereby more or less neutralizing its own effects. The tape records made with this system and an ordinary system show marked advantage in this system for reducing the effects of static and for increasing speed of recording.