Patent GB-375857-A (GB)
Title: Improvements in or relating to telegraph distributor systems
IPC: H04L5/24
Filed: 1931-04-01
Abstract: 375,857. Multiplex telegraphy; thermionic distributers. STANDARD TELEPHONES & CABLES, Ltd., DUNHAM, C. R., and ROCHE, A. H., Connaught House, Aldwych, London. April 1, 1931, No. 9865. [Classes 40 (iii) and 40 (v).] A number of independent start-stop telegraph transmitters are associated with a high-speed distributer in constant rotation or cyclic operation by an arrangement such that the transmission to the high-speed distributer of the impulses from the various transmitters is effected irrespective of the position of the distributer in its cycle and the impulses are then transmitted in correct sequence to a line. The invention is adapted to overcome the difficulty which may arise if an impulse from any of the transmitters is changing sign during the short interval in which the corresponding segment of the high-speed distributer is effectively connected to the transmission line. The arrangement is such that if an initial impulse of a signal combination is initiated from a transmitter when the distributer is scanning, or is within predetermined limits of scanning, the corresponding segment of the high speed distributer, the impulse from the distributer is delayed until the segment is connected to the line during its subsequent revolution. On depression of a key of a start-stop transmitter A, the start impulse, which consists of a period of no current, releases a magnet 16 of a switch member 22 permitting an arm 17 to pass over a continuous segment 18 in synchronism with the start-stop transmitter shaft. The impulses from the segments 1 .. 5 and the stop segment are applied in parallel to relays 11, 12, the relay 12 being arranged to be retarded by a time interval corresponding to half the period of revolution of the high-speed distributer 25. The segments xl, x2 .. are individual to the transmitters, and the distributer is arranged to connect all the segments x1 .. x12 to the line during the time allotted to a single impulse from a transmitter. A relay 14 individual to a channel (transmitter) is associated with the distributer so that it is energized once during each revolution of the distributer, and when the arm 17 is in its latched position, as shown, the armature of a relay 13, controlled by the relay 14, is vibrated in synchronism. The relay 13 is locked in the position it occupies (or to which it is moving if it is in motion) at the instant when the arm 17 moves on to the continuous segment 18 and the setting of relay 13 is determined by the position of the high-speed distributer in its cycle with respect to the segment x1, x2 .. individual to the transmitter under consideration. If the relay 13 is in the operated position, the impulses from the distributer during its successive revolutions will pass to the line or to earth over the operated or unoperated contacts respectively of relay 11, which will be energized or de-energized in accordance with the impulses from the associated start-stop transmitter. If the relay 13 is locked in its unoperated position, the impulses will similarly pass from the distributer over the contacts of relay 12 in accordance with its retarded energization or de-energization by the impulses from the associated start-stop transmitter. At the receiving end the impulses are applied over the appropriate segments of a high-speed distributer to corresponding trigger devices 24 which are operated on marking impulses and repeat the corresponding impulses to the associated receiver, shown diagrammatically at D. The trigger device 24 is arranged to be operated only when a signal impulse is superimposed on the impulse received from the distributer. The high-speed distributer 25, shown as a mechanical distributer in Fig. 1, is normally replaced by a valve distributer, Fig. 3 (not shown), whose arrangement and operation are described in Specification 357,532. In the system shown schematically in Fig. 4, the segments of the mechanical distributer or their analogue are conditioned for simultaneous transmission and reception. The elements X1, X2 .. X12 represent segments of a distributer from which impulses are sequentially produced and which pass via condensers C1 .. C12 to the line in accordance with the setting of signal contacts S1, S2 .. S12 which may be directly controlled by transmitters or may correspond to the relay arrangement 11 .. 14 of Fig. 1. The signal impulses are passed to a transmitting corrector device T.C. by which the signals are shaped so that overlapping is avoided. Simultaneously with the application of an impulse to the condenser C1, an impulse passes from the distributer segment to a trigger device T1. Associated with the incoming line are a line trigger device LT, and a receiving corrector RC through which the incoming signal is made of a length to prevent overlapping. The trigger devices T1, T2 .. , which may be of the type described in Specification 352,401, are arranged to be operated only when a line signal impulse is received simultaneously with the impression of the impulse from the associated segment X1, X2 .. of the distributer and are associated with separate telegraph receivers. Fig. 5 shows diagrammatically a complete system for associated transmitting and receiving stations incorporating the arrangements shown in Figs. 1 and 4, and with arrangements for synchronization and for starting the system into operation. The transmitting and receiving instruments are associated with relays R1, and trigger relays TR which co-operate simultaneously with a distributer D to which are fed controlling waves from an oscillator O for the operation of the distributer through a phase-shifter PH from which the output is fed in parallel to a squaring device SD, and to the transmitting and receiving correctors TC1, RC1. The controlling wave is also fed to the line L3 and through a filter F1, which accepts the synchronizing frequency, to a controlled oscillator 02 whose output is fed to a squaring device SD2 and is utilized to control the distributer D2 and the transmitting and receiving correctors TC2, RC2 of the distant station. A part of the output of the oscillator 02 is fed through an amplifier A8 and a phase shifter PH4 to neutralize, at the input of the line trigger device LT2, the part of the synchronizing frequency which passes through A4. To start the system into operation, the contacts of the relay SR at the receiving end are closed manually and a start key SK at the transmitting station is operated to energize a neon-tube relay NK which sets into operation the distributer D1 and at the same time passes an impulse over the line L3 and operated contact of relay SR to the distributer D2. The impulse also operates relay LT2 causing the start relay SR to fall off, thus opening its circuit at its upper contact. The telegraph signals may be converted to high frequency before transmission over the line, and rectified before being applied to the trigger devices LT1, LT2.