Patent GB-433862-A (GB)
Title: An improved method of transmitting telegrams through the medium of one or more exchanges
IPC: H04L12/54
Filed: 1933-11-20
Abstract: 433,862. Telegraph exchange systems. KLEINSCHMIDT, E. E., 333, North Michigan Avenue, Chicago, U.S.A. Nov. 20, 1933, No. 32317. Convention date, Jan. 5. Drawings to Specification. [Class 40 (iii)] In an automatic printing telegraph exchange system the calling subscriber produces at the exchange, after the automatic connection of his telegraph instrument, a perforated tape which bears the code address of the called subscriber and the text of the message and which takes the place of the calling subscriber for establishing the connection and performing the message transmission without a direct connection existing between the calling and called subscribers. On making a call the subscriber is initially connected to two perforators, one of which is automatically disconnected if the message is of an urgent nature determined by the first letter of the code address of the wanted subscriber. The tape is perforated according to the address of the called line in duplicate, the text of the message, a special combination of signals to effect the operation of an " answer-back " device when the message has been transmitted to the called subscriber and the code address of the calling subscriber in duplicate followed by a " message-end " signal which disconnects the calling line from the exchange. When the calling subscriber has been disconnected the perforator brings into operation a transmitter provided with separate arrangements for establishing the connection and for the transmission of the message. The first arrangement is controlled by the address in duplicate and operates so that if the duplication of the address has not been correctlv performed or if the coded address is not served by the automatic selector system, a warning signal is provided. The exchange operator connects his receiving apparatus to the transmitting arrangement which returns the tape to its initial position and repeats the address and, if necessary, the text of the message which are received on the exchange receiver. If necessary a correction is effected or the message is transmitted to the nearest station served by the automatic system. The coded address effects the extension of the connection through selectors having character bars falling into aligned notches of code bars selectively set in accordance with the five-unit code. The character bar selected closes contacts for extending the selecting, transmission and testing circuits to a subsequent selector and through a final selector to the wanted line. Associated with a final selector is an " answerback " arrangement forming the subject matter of Specification 434,190, which is brought into effective operation by the special " answer back " signal combination and which transmits the coded address of the calling subscriber in duplicate together with the code address of the called subscriber to a perforator controlling a transmitter arrangement which automatically effects connection through selectors to the originating station where the printer is operated to record an answer-back message comprising the code address of the originating station in duplicate together with the address of the called subscriber station. Each subscriber station is provided with mechanism for counting the number of words transmitted or received, and the numbers set up by the mechanism are printed on a tape at the end of a message transmission. The teleprinters at the subscriber stations operate so that message transmission is prevented until a connection to the exchange has been established and until the motor has reached its normal running speed.