Patent GB-535587-A (GB)
Title: Improvements in or relating to signaling system
IPC: H04J3/04
Filed: 1939-10-17
Abstract: 535,587. Type-printing telegraphy; thermionic distributors. INTERNATIONAL BUSINESS MACHINES CORPORATION. Oct. 17, 1939, No. 28068. Convention date, Nov. 10, 1938. [Classes 40 (iii) and 40 (v)] In a signalling system using thermionic distributers at each station, synchronism is ensured by a series of synchronizing impulses at regular intervals. In the system described, the transmitter A, Fig. 1, comprises a phase-splitting transformer 10, similar to that described in Specification 469,761, but producing two sets of four waves, each of the four waves being 45 degrees out of phase with the next but in phase with the corresponding one of the second set. To each of these eight outputs is connected a double-diode-triode valve, as in Specification 497,865, with the condenser 24 connected to one diode anode for one set of waves and to the other diode anode for the other set. By this means there are produced at the outputs of the double-diodetriodes TI ... T8 a recurring series of impulses each 22¢ degrees out of phase with the preceding one. In Fig. 1 valves T1 ... T6 produce the first six impulses and are used for signalling combinations, T7 is not shown but is intended to be used for any monitoring or other function, and T8 is used for producing synchronizing impulses and initiating the operation. Closing of the main contact 41 at the transmitter passes current to T8 which thereupon produces a pulse which passes in parallel through an amplifier 39 to line 42 and to the grid of a triode 11. This triode 11 immediately oscillates at the frequency of the circuit 33, 34 and the alternating output passes to the phase-splitting device 10 which thereupon tends to produce spaced impulses in the valves T1 ... T6. However only if the signal combination contacts 12 connected in the output leads of the valves are closed are impulses actually produced, in which case they are passed by a lead 26 to the amplifier 39 and line 42. At the receiver B the synchronizing or start impulse is received on a transformer 45 and amplifier 44 whereupon a momentary current passes through a lead 46 to triode R8 which produces a momentary impulse and causes oscillation of a triode 11a whose oscillatory circuit 53, 54 is tuned to the same frequency as that at the transmitter. The output from this valve passes to a phase-splitting device 10a identical with that at the transmitter and thereby tends to produce tuned impulses in the output circuits of the triodes R1 ... R6 at the same instants as impulses are being produced in corresponding valves at the transmitter. The output circuit of any particular valve R1 ... R6 is not however completed unless the grid potential of the amplifying triode 44 is raised above cut-off by an incoming impulse at the appropriate instant. A current then flows from the H.T. supply F through triode 44, valve R1 ... R6, corresponding impedance L1 ... L6 to the negative of the supply. This causes a charge to be applied to a condenser Cl ... C6 and if the corresponding transmitting contact 12 is retained closed for a short time the cumulative charge on the particular condenser C1 ... C6 is sufficient to raise its potential to a point at which the grid of the corresponding triode A1 ... A6 is no longer cut-off. A current then flows through the appropriate electromagnetic control device 13. For signal code combinations a number of the transmitting contacts 12 are closed simultaneously whereupon the corresponding devices 13 at the receiver are operated.