Patent GB-670762-A (GB)
Title: Electrical multiplex to start-stop telegraph signal converters
IPC: H04L5/24
Filed: 1949-09-30
Abstract: 670,762. Multiplex telegraphy; thermionic distributers. TELETYPE CORPORATION. Sept. 30, 1949 [Oct. 15, 1948], No. 25190/49. Class 40 (iii). Apparatus for associating a multiplex channel with a start-stop receiver comprises means for storing the signals received from the multiplex distributer, and a start-stop thermionic distributer controlled by a start-stop oscillator for controlling the retransmission of two stored signals with the addition of start and stop signals. In the system shown, five-unit code signals received from the multiplex distributer over plug 11 are stored on tubes 13 ... 17, each of which is fired if the corresponding code element is a mark. The firing of any one of these tubes transmits positive potential over lead 19, switch 21 (in the position shown) and lead 22 to operate the left-hand section of double-triode 23, thereby releasing, through the common anode resistor 27, a normallyconducting gas tube 26. When a signal is completely stored, an operating pulse is sent back over plug 11 to lead 29, e.g. in the manner described in Specification 670,759. This refires tube 26, causing a positive pulse to be transmitted through the left-hand section of double-triode 34 to fire the distributer start tube 37. The common anode connection 38 to tube 37 and to distributer tubes 40 ... 44 is also connected to the grid of the normallyconducting right-hand section of valve 48 which thereby becomes non-conducting as soon as tube 37 is fired and removes positive potential from lead 49 causing the start-stop oscillator 51 to start. The sine-wave output on lead 53 is squared in amplifier 54 and applied through a condenser to the grid of the left-hand section of valve 57 producing positive pulses in the cathode output lead 59 connected to the control grids of the distributer tubes 40 ... 44. Each of the tubes 37, 40 ... 44 primes the next over circuits 63 so that tubes 40 ... 44 will be fired in succession. A marking signal normally exists on the line 69 to the start-stop receiver 68, relay 72 being operated in the anode circuit of the normallyconducting right-hand section of valve 23. During the operating period of start tube 37, the right-hand section of valve 34 conducts, lowering the potential on anode lead 73 and causing valve 23 and relay 72 to release to transmit the spacing start signal. During the operating period of distributer tube 40, the grid of the left-hand section of valve 66 is conditioned and if tube 13 is fired indicating a mark, positive potential on lead 64 prevents valve 66 operating, the full potential on anode lead 73 is available for valve 23 and relay 72 re-operates to transmit a mark. Similar operations occur for the remaining stored elements and after the transmission of the fifth the lefthand section of valve 48 is momentarily operated by the next pulse on lead 59. The righthand section of valve 48 operates again and stops the oscillator. Each of the distributer tubes 41 ... 44 when fired sends a pulse to operate the right-hand section of the tube 66 ... 77 corresponding to the preceding element to release the corresponding storage tube 13 ... 16 if operated. Storage tube 17, if operated, is similarly released by full battery potential on lead 88 when the distributer has stopped. With switch 21 in its alternative position, the starting of the distributer chain is effected by the firing of a sixth storage tube 91 over a lead 92. This is employed when it is necessary for a blank signal to be recorded in the start-stop receiver 68 since the distributer would not be started over lead 19 if no marks are received. Specification 670,758 also is referred to.