Patent GB-364704-A (GB)
Title: Improvements in submarine cable signal tranmission systems
IPC: H04M11/06
Filed: 1930-10-16
Abstract: 364,704. Multiplex typeprinting telegraphy. STANDARD TELEPHONES & CABLES, Ltd., SANDEMAN, E. K., GRACE, B. B., ROCHE, A. H., and SKILLMAN, T. S., Columbia House, Aldwych, London. Oct. 16, 1930, No. 30976. Addition to 342,370. [Class 40 (iii).] In the system described in the parent Specification each code element is represented by a different frequency, the signals comprising combinations of these frequencies taken one or more at a time and being sent simultaneously over a combined telegraph and telephone submarine cable and the signals themselves controlling the receiving apparatus to receive successive signals. The apparatus at the transmitting end is modified so that the telegraph signals in the cable when a telephone transmission is commenced from the distant or receiving end, are discarded, and are retransmitted when the telegraph transmission is. resumed. The contacts corresponding to the letters set up on the transmitters 1 .. 5 are selectively connected through the contacts of a distributer bank to the appropriate relays A .. E associated with the five frequencies by the brush of a distributer DA rotated by a step-by-step magnet SM intermittently energized through a relay M, m from impulse springs I. At the same time the springs I energize through normal contact l<2> a stepping magnet SM<1> controlling a counting switch DB which on its fifth contact energizes a relay L opening at l<2> the circuit of the magnet SM<1>. At operated contact l<3> earth is applied to the brush passing over the upper row of the contact bank by which the magnets DM of the transmitters are operated to step the tape for the next letter from the corresponding transmitter. On the change over to telephony at the distant end a relay G at the transmitting station is energized. At contact g<4> the circuit through the springs I is broken, and at g<3> the magnet SM is placed in a self-interrupting circuit. At g<5>, g<6> the line is switched through to the telephone apparatus, and at contact g2 the earthing circuit for the upper contact row is opened. With the operation of contact g<4>, a slow-to-release relay J, associated with and individual to each set of contacts, operates, and at its contact connects earth to a terminal in another row of the contact bank and four letters previous to the operating contacts A relay H, operated when the brush has been stepped round to this earthed contact, opens at h<1> the circuit of the stepping magnet SM and locks up over h<2>. Over contact g<1> a magnet R is energized to operate a pawl releasing the switch DB to return to its initial position. When telegraph transmission is to be resumed, the relay G is released and the circuit through the impulse springs I and the magnet M operating the stepping magnet SM is again closed. According to the Figure, if the changeover occurs as a signal has been sent from transmitter 5, the brush will be automatically stepped to the first set of contacts, and the letters set up on the five transmitters 1 .. 5 will be repeated to the line L. Specification 335,935, [Class 40 (iv), Telephones &c.], is referred to.