Patent GB-348565-A (GB)
Title: Improvements in or relating to electric signalling systems
IPC: H04L25/40
Filed: 1930-02-07
Abstract: 348,565. Code telegraphy. WESTERN UNION TELEGRAPH CO., 195, Broadway, New York, U.S.A. Feb. 7, 1930, No. 4217. Convention date, Feb. 27, 1929. [Classes 40 (iii) and 40 (v).] Thermionic receivers for line telegraphy. An electric telegraph receiving system includes a gas-filled thermionic valve comprising an anode, a cathode and a starting electrode or grid such that when the potential of the grid is made positive, and the plate circuit is closed, current continues to flow irrespective of grid changes until the plate circuit is opened. The received impulses are applied to the valve by a brush rotating over solid and segmented rings and the output circuit of the valve is completed through a second brush and segments connected to printer magnets or storing relays. The output of an amplifier A. Fig. 1, is applied through a solid receiving ring 1 and segments 9 to the grid G of a valve 2. The plate filament circuit of the valve 2 is completed by a ring 3 and brush 6 to printer magnets and a battery 4. If a positive impulse is received the valve is " started " and current flows through a printer magnet, the circuit being broken by a " dead " segment 7. A stabilizing battery C1 applies a normal negative potential to the grid G. Restoring lost impulses.-Ineffective or missing signal impulses are interpolated by the arrangement shown in Fig. 2. The impulses received are applied through the brush BR1 to segments alternately connected to the grids of two thermionic valves 2a, 2b of the type described. One side of the amplifier is connected through a resistance R to the filaments of the valves. The plate circuits of the valves include solid rings " A," " B," connected to overlapping segmented rings " A," " B," the printer magnets, a battery 4 and resistance R to the filaments. A battery C3 applies to each grid a small positive potential somewhat greater thar. the negative potential, applied individually by the small stabilizing batteries C1, C2. When no effective signal is received through the amplifier, the battery C overrides the battery C1 or C2, and on the operation of the valve, current flows through the printer magnets. Should the succeeding signal be ineffective, the battery C3 again tends to override one of the batteries C1, C2, but on account of the overlapping arrangement of the " A " and " B " segments, current will still be flowing through the resistance R to impose an effective negative voltage on the grid of the corresponding valve. In this case, the valve will not be operated, and current will not flow through the printer magnets. Duplex telegraphs ; artificial lines.-The system adapted for duplex working, Fig. 3 (not shown), is similar to that shown in Fig. 1 except that the received impulse is applied from the conjugate arm of a receiving bridge. An alternative arrangement for duplex working, Fig. 4 (not shown), is similar to that shown in Fig. 1, the secondary winding of a transformer corresponding to the amplifier A. The primary of the transformer is connected through segmented rings to the receiving arm of an artificial line bridge, and a ring, similar to the ring 1, of Fig. 1, is arranged so that the first portion only of a received impulse is applied to the grid. Repeating systems using contact - making relays.-Fig. 5 shows duplex arrangement by which signals received from a line EL are regenerated and transmitted to a line WL. Alternate segments of the printer ring are connected to the coils of relays R, R<1> in the plate circuit. A synchronous brush 7 connects to the windings r, r<1> of the relays R, R<1> negative battery, which operates the armatures to their negative contact when the valve is not operated by a positive signal. When a positive signal is received to operate the valve 2 the current flowing in the plate circuit is arranged to be greater than that in the coils r, r<1> and the corresponding armature is moved to its positive contact. Synchronous movements. In Fig. 6 a system is shown in which one valve is employed to receive signals and a second valve controls an electromechanical arrangement for applying a phase correction to the rotary distributor. The receiving lines are connected through a resistance R to the filaments of the valves A, B, and through a brush BR1 to segments 20, 21 connected to the grids of the valves. The plate of the valve A is connected through a brush BR2 to printer magnets, a battery B1, a resistance R and the filament of the valve A. The plate-filament circuit of valve B is completed through contact 25, corrector magnet CM, and battery B2. The segments 20 are arranged to select the approximate centre of the received signals of unit length, and when a positive signal has been received, current is still flowing in the plate circuit of the valve A as the brush BR1 passes on to a segment 21. The negative potential applied by current flowing through the resistance R overcomes the positive potential of the signal and the valve B will not be operated. The valve B can therefore only be operated at the beginning of a positive signal and if the brush BR1 has been displaced relative to the incoming signals so that a positive signal has reached an effective amplitude as the brush engages a segment 21, the valve B will be operated. Current flowing in the plate circuit energizes the corrector electromagnet CM, and a pawl 29 operates a ratchet wheel 30 connected by a clutch (or its equivalent) to a shaft carrying the brushes. Small stabilizing batteries C1, C2 apply a normal negative voltage to the grids of the valves A, B. Specification 346,478 is referred to.