GB264186A - Process for indirect telephonic transmission - Google Patents

Abstract

264,186. Campos, G. Jan. 9,1926, [Convention date]. Void [Published under Sect. 91 of the Acts]. Telephone systems; diplex systems.-Messages to be transmitted by wire, wireless or wiredwireless telephony are first recorded on a device F of phonograph &c. type from which they are reproduced at any desired faster or slower speed to control a transmitting microphone M. At the receiving end, the signals actuating the receiver T are recorded on a second recording-device F<1> and are reproduced therefrom at the original speed. Transmission over a line L at a high speed ensures the use of the line for a minimum time and by the use of filter circuits high-speed and ordinary telephony can be carried on simultaneously. On the other hand, transmission at a low speed is useful for transmission over very long lines in which the distortion except for very low frequencies would be prohibitive. Messages transmitted at such high or low speeds are difficult to understand but additional secrecy can be obtained by reversing the direction of the record when reproducing from the device F and subsequently reversing the received message at the recording device F<1>.