GB288636A - Improvements in electrical signal transmission systems - Google Patents

Abstract

288,636. Lovejoy Development Corporation, (Assignees of Lovejoy, D. R.). April 15, 1927. [Convention date]. Modulating systems; diplex signalling.-The positive and negative halfcycles of a carrier wave are modulated independently so as to provide two channels of communication which can be used separately or simultaneously. The transmitter, Fig. 1, comprises an aerial 12 energized by an oscllator 10 through two oppositely - connected rectifying-valves 13, 14, the positive half-cycle passing through one valve, and the negative through the other. Modulation arising from separate microphones 23 is applied to the grids of the valves. At the receiving-station, Fig. 5, the aerial 59 is coupled to a tuned circuit across which are connected separate phones 50, 51 in series with oppositely-arranged crystal or other rectifiers 52, 53. It is stated that the phones thus receive simultaneously and independently the messages transmitted by the microphones 23. In an alternative arrangement for consecutive reception of the messages, a. single pair of phones is used and a switch is arranged to reverse the connections of a single crystal. Separate aerials may be used.