Patent GB-529345-A (GB)
Title: Improvements in or relating to telegraph transmitting mechanism
IPC: H04L12/06
Filed: 1939-05-30
Abstract: 529,345. Telegraphy. STEVENS, A. H. (Western Union Telegraph Co.). May 30, 1939. No. 15894. [Class 40 (iii)] An automatic transmitter comprises means for transmitting groups of code combinations and means for automatically varying the code transmitted in a predetermined manner. The transmitter described is designed for sending before each message, sent by a perforated tape transmitter, predetermined signals designating, e.g. the originating point of the message, the number of the message, and, in the case of multiplex working, the channel used. The signals denoting the origin of the message are invariable but the signals indicating the number of the message vary with each message so as to send consecutive numbers. The signals are sent on the 5-unit system to control a typeprinting receiver, and the invariable signals may include " letter-shift and " figure-shift " signals to ensure the necessary change of case at the receiver. In one system described, the following signals are sent-(1) the "letter-shift" signal, (2) the letter F, (3) the letter W, (4) the letter D, these letters F, W, D constituting the fixed part of the signals, (5) the "figures-shift" signal, (6) a tens digit, (7) a units digit, these constituting the variable signal, and (8) a " letters-shift " signal. The signals are set up by pins on rotating drums, the pins influencing sets of contact springs which are associated in turn with contacts closed in sequence by a series of cams or with the segments of a distributer. The " invariable " signals are set up on one drum, separate drums being used for the tens and units signals. After each complete set of signals has been sent, the units drum is moved one step, so as to increase the units digit sent with the next message, and after a complete rotation of the units drum, the tens drum is moved one step to vary the tens digit next transmitted. (1) In the first modification described (Figs. 1 to 10, not shown) the several sets of contact springs controlled by the "letter," "tens" and "unit" drums are associated in turn with contacts closed in sequence by a series of cams. The perforated-tape transmitter terminates in a plug, the insertion of which in the jack associated with the auxiliary transmitter initiates the operation of the latter. When the complete set of signals has been sent, a transfer relay disconnects the auxiliary transmitter and connects up the tape transmitter. (2) In a second modification (Figs. 11 to 15, not shown), no invariable signals are sent except the letter and figure shift signals, and hundreds, tens and units drums are all mounted on a common shaft, the contacts controlled thereby being associated in turn with the contacts of a multiplex distributer by cams on a further drum on the same shaft. The transmission is initiated by the depression of a key and when it is completed a transfer relay disconnects the auxiliary transmitter and connects the tape transmitter to the distributer contacts. (3) In a third modification, the auxiliary transmitter is connected to the distributer contacts by a relay operable by two or more predetermined code combinations punched in the perforated tape and preceding each telegraph message. The contacts 1 ... 5 of the tape transmitter TR<SP>11</SP> are connected to relays 181a ... 181e and over the contacts of relay CR<SP>11</SP> to the distributer segments. When, and only when, the particular combination of relays 181a ... 181e corresponding to the predetermined code is energized, a circuit is closed by the distributer for magnet 185 which moves the ratchet 184 one step. If the same combination is set up by the next set of perforations, magnet 185 moves the ratchet 184 a second step, thereby closing at contact 195 a circuit for the control relay CR<SP>11</SP> which connects the distributer segments to the auxiliary transmitter instead of to the tape transmitter. If any other combination had been set up on relays 181a ... 181e, relay 182 or 183 is energized and causes magnet 187 to release the ratchet 184. (4) In a fourth modification (Figs. 17 to 20, not shown), resembling the first, the contacts of the auxiliary transmitter controlled by the letters, units and tens drums are associated in turn with the contacts of the distributer by relays. The operation of the auxiliary transmitter is initiated by the insertion of a multi-spring plug associated with the tape transmitter in a jack connected to the auxiliary transmitter. When the auxiliary transmitter has finished sending, the distributer contacts are connected to the tape transmitter, and when this has completed the: transmission of the message a succession of predetermined code perforations stops the tape, the circuits closely resembling those in Fig. 16.