GB641572A - Improvements in or relating to telegraph transmitters - Google Patents

Abstract

641,572. Type-printing telegraphy. STANDARD TELEPHONES & CABLES, Ltd. Dec. 17, 1947, No. 33288. [Class 40 (iii)] In a five-unit telegraph or like code transmitter each code combination is represented by a chain of electronic discharge devices which are fired sequentially, those representing marks and those representing spaces operating transmitting means to transmit a marking or spacing condition respectively, and the number of such devices for the first element of said code combinations is equal to the number of such combinations but for at least some of the succeeding elements the number of devices is progressively halved. In Fig. 1 each black circle represents a cold-cathode tube with three electrodes, the anodes of which are each connected to battery through a common mark winding of a telegraph transmitting relay. Each white circle similarly represents a tube connected to the space winding of the relay. The tubes are connected in thirty-two chains as shown, each combination representing a different character and each associated with an individual contact 1. When any particular contact, say 8, is closed as by a key of a keyboard a common start contact 11 is also closed and a normally conducting stop tube 9 sends a priming pulse to the cathode of a start tube 10 which conducts when it receives the next pulse from a square-pulse generator connected in parallel to all control electrodes. The five tubes of the particular code chain to which the start tube is now connected then conduct in turn as described in Specification 613,137 under control of the timing pulses from the common generator, and as each tube conducts the corresponding telegraph relay winding is energized to transmit to line the required combination of marks and spaces. Finally the common stop tube 9 conducts. If the contacts 11 and 8 remain closed because the character key is still depressed the character will be retransmitted. In Fig. 4 (not shown) this difficulty is avoided by arranging for the depression of a key to energize a relay whose start contacts connect the start tube in circuit over further relay contacts which are opened when the start tube has fired. The common start tube may be replaced by an individual start tube in each character chain (Fig. 3, not shown) and the final code tubes of Fig. 1 may be duplicated so that each serves only eight character combinations.