Patent GB-556340-A (GB)
Title: Regenerative telegraph repeater
IPC: H04L25/04
Filed: 1942-06-04
Abstract: 556,340. Code telegraphy. STANDARD TELEPHONES & CABLES, Ltd. June 4, 1942, No. 7600. Convention date, Feb. 25, 1941. [Class 40 (iii)] In a regenerative telegraph repeater, particularly for teleprinter start-stop signals, the duration and timing of the outgoing signals is controlled by a condenser-resistance combination associated with a valve. Fig. 1 shows a transmitter A connected to a receiver B through an exchange repeater comprising a receiving relay C, a sending relay E, a locking relay H, and auxiliary relays D, F, G. The locking relay H is in the anode circuit of a valve T2, the grid of which is connected to a condenser 12 which is negatively charged by battery 17 when the armature of relay H is on its marking contacts; the relay H is thus energized for short periods at, say, 22 milli-second intervals, and controls a locking-circuit for relays D, E. The relay G is similarly associated with a condenser 10 and valve T1, the relay G being locked by current through the valve for, say, one-sixth of a second, the period of transmission of one character. With marking current on the line L1, the armatures of the relays are normally in the positions shown. The start impulse moves the armature of relay C to its spacing position, in which current from battery passes through the upper windings of relays D, E and tends to move their armatures to spacing position but is prevented from so doing by current through their lower windings from battery 17. Current from battery also passes through relays G, F, moving their armatures to spacing position in which they are held for one-sixth of a second (the period of a character) by current from battery 9 through resistance X. Relay F disconnects potentiometer 11 from condenser 12, which discharges through resistance 36 and after 11 milliseconds permits current to flow through valve T2 to cause relay H to move its armature to marking position, thereby connecting the higherpotential battery 17 to condenser 12, which is thus charged negatively and interrupts the current through valve T2 and relay H. This operation is repeated so that relay H is momentarily energized at intervals of 22 milli-seconds. When armature of relay H moves back into its spacing position, and only then, the circuit through lower windings of relays D, E isopened, so that the armatures of these relays can be moved by the current in their upper windings to a position determined by the armature of relay C, thus repeating the signals to station B. When the armature of relay M moves back into its spacing position, a holding circuit is re-established through the lower windings of relays D, E in a direction determined by the position of the armature of relay D. After one-sixth of a second, i.e. at the end of a character, condenser 11 has discharged sufficiently to allow current to pass through valve T1 and the lower winding of relay G, thereby moving its armature to marking position so that relay F also moves its armature to marking position as soon as the armature of relay C moves to marking position. Relay F thus connects potentiometer 11 to condenser 12, thereby arresting the intermittent operation of the relay H. A two-way repeater is also described, Fig. 2 (not shown), operating on the same principle but provided with a " pre-erupting " relay which gives control of the repeater to that station which starts transmitting first. This control, however, only lasts until the end of the character, whereupon the other station may break-in and start signalling.