Patent GB-434190-A (GB)
Title: Improvements in electric telegraph message transmission systems
IPC: H04L12/54
Filed: 1933-11-20
Abstract: 434,190. Telegraph exchange systems. KLEINSCHMIDT, E. E., 333, North Michigan Avenue, Chicago, U.S.A. Nov. 20, 1933, No. 21336/35. Convention date, Jan. 5, 1933. Divided out of 433,862. [Class 40 (iii)] A telegraph system having a number of subscriber stations provided with teleprinters incorporates one or more " answerback" devices operating so that after the transmission of a message from one subscriber to another the sending subscriber is automatically notified that the message has been received. The " answerback" device, which is provided at the exchange when the connection between the subscribers is automatically effected, is brought into action by the combination of characters " Shift " and " H " which are prefixed before the repeated signature of the sending subscriber. At the end of the transmission of his telegram the originating subscriber receives a return message incorporating his number or designation in duplicate together with that of the called subscriber. When, as described in Specification 433,862, the connection has been established through the line selector to the called subscriber, relay 622 energizes and operates relay 672 which allows the arm 671 of a distributer 670 to move to a second stop position in which it is held by the short arm 678 of the armature 673. On completion of the message transmission circuit of the called subscriber, relay 623 operates and responds to the transmitted impulses which are passed to a distributer 700 forming part of the "answer back" device. These impulses are transmitted over the lower contacts of a relay 706 to magnets 721 ... 725 whose top and middle armature are connected in code manner according to the characters " shift " and " H " respectively to form operating circuits for a slowrelease relay 726 and a relay 727. When the characters " shift and " H are received in succession relays 726, 727 operate and complete the circuit of the relay 706 which moves its armatures 736 to upper contacts connected to perforator magnets 712. Relay 706 also operates the magnet 416 of the message indicator described in Specification 433,862. and over segments 681 connected by the brush 675 of arm 671 energizes a relay 624 which is associated with the called line and whose armatures are selectively connected according to the code combination of the last letter of the designation of the called subscriber. The address of the calling subscriber is perforated in duplicate in the tape 720 and a message end signal disconnects the distributer 700 from the relay 623. When the connection has been broken, relay 622 releases and de-energizes magnet 672 which frees the arm 671. During its rotation over the segment 685, impulses are passed to the distributer 700 and to the perforator magnets 712 which record "lettershift on the tape. As the arm 671 continues its rotation impulses according to the letters permanently set up on the segments 691, 694 are passed by distributer 700 to the perforator magnets, followed by the impulses corresponding to the last letter of the address of the called subscriber which have been prepared at the contacts of the "letter" relay 624. The passage of the arm 671 over a set of contacts 683 transmits impulses directly to the magnet 707 stepping the tape to the transmitter which effects the connection to the originating subscriber as described in Specification 433,862, and transmits to him the notification containing his designation in duplicate and that of the subscriber to whom the message has been transmitted. When the arm 671 passes off the segments 681, 682 the operated relays are released and the "answerback" device is returned to normal in preparation for use with a subsequent connection.