Patent GB-255801-A (GB)
Title: Automatic telegraph receiving apparatus
IPC: H04L15/32
Filed: 1925-08-31
Abstract: 255,801. Western Union Telegraph Co., (Assignees of Angel, H.). July 21, 1925. Restoring or modifying imperfect signals; perforated-strip recorders; synchronous movements. -Block signals received over a submarine cable are separated into tneir compartment impulses which are applied to operate a motor-driven stripperforating recorder and to control the speed of the motor for maintaining the recorder in synchronism with the signals. The cable relay 50 controls a dot relay 52 and a dash relay 53 of which the tongues, when on their marking contacts, connect - and + battery respectively to earth through conductor 57 and a relay 58 controlling a fork or reed 63, and to earth also througn relays 76. 78, and contacts 79 periodically closed by a cam 80 on the shaft 26 of a directcurrent motor 10 driving the perforator P. The motor is adjusted to rotate the shaft 26 approximately once per unit signal period, and is provided with a winding and slip rings for supplying alternating current through the secondary of a transformer 71, and the transformer primary is connected at its ends to contacts 72, 73 engaged alternately by the fork 63 and at its mid-point to - battery. The resulting currents, passing through the two halves of the primary alternately produce in the secondary an alternating current which brings the motor into exact synchronism with the fork. The rate of free vibration of the fork is adjusted to approximate synchronism with the transmitter and the vibration is maintained and brought into unison with the received signals by impulses through a magnet 61 in circuit with a condenser 60 and the tongue and marking contact of the relay 58, the condenser being subsequently discharged through a resistance 67 and the spacing contact of the relay. The shaft 9 of the perforator tape-feed wheel 8 is driven from the shaft 26 of the motor 10 through gears 11, 12, shaft 12<1>, worm 13, and worm wheel 14 the wheel 14 being held by a spring 16 in frictional engagement with a collar 15 on the shaft 9. The punches 18, 19 are actuated by a hammer 20 carried by a member 21 reciprocated by a cam groove 24 in a shaft 25. This shaft is driven through a friction clutch from the shaft 26, and is normally held against rotation by the engagement of a rod 31, with a stop 32 on the shaft. Upon receipt of a signal, the tongue of one or other of the relays 76, 78 closes a circuit through a relay 87 which in turn closes the circuit of a magnet 90 to move the arm 31 and thus to release the shaft 25. The hammer 20 is moved over the punch 18 or the punch 19, according as the signal is a dot or a dash. by a rod 41 operated by the armature of a polarized magnet 40 energized by the operation of one or other of the relays 76, 78. To hold the tape stationary during the punching operation a toothed wheel 38 on the shaft 9 is engaged by a wedge member 37, reciprocated by a cam groove 35 in the shaft 25, and to advance the shaft 9 subsequently by a corresponding amount to compensate for the loss of rotation during such holding action, a second wedge member 45 operated alternately with the member 37 engages inclined teeth of a second wheel 46 on the shaft 9. The signal impulses may alternatively be regenerated by the methods described in Specifications 196,879 and 196,980.