GB275595A - Improvements in or relating to high frequency telephony - Google Patents

Abstract

275,595. Telefunken Ges. f³r Drahtlose Telegraphie. Aug. 6, 1926, [Convention date]. Duplex signalling; wired-wireless systems.-In a high-frequency telephone system only a single carrier frequency is produced at one of the stations and is employed for speaking in both directions, and each station is provided with a selectively-connectable oscillation generator Z which serves for calling and for speaking in both directions. At the called station the carrier frequency received in the pauses of the speech is utilized for the transmitting modulator. A differential transformer B and a balancing network N, Fig. 3, may be employed to separate the modulator M and demodulator D. In a modification, Fig. 2, the separation is effected by a compensating circuit E. In the application to power lines L1, L2, chokes Sp1, Sp2 and condensers C1, C2 are pro. vided to separate the power and signalling circuits. In a further modification, Fig. 4, separate lines L1, L2 are employed for each way indicated by the arrow. The Specification as open to inspection under Sect. 91 (3) (a) comprises also a system in which a single generator is provided and is arranged at a central station, while at the sub-stations harmonics of the carrier frequency generated may be utilized for signalling. This subject-matter does not appear in the Specification as accepted.