Patent GB-213302-A (GB)
Title: Improvements in electric telegraph apparatus
IPC: H04L7/00
Filed: 1922-10-28
Abstract: 213,302. Pernot, F. E. Oct. 28, 1922. Synchronous movements; repeating systems using contact-making relays; restoring or modifying imperfect signals. - In the utilization of impulses corresponding to either end or both ends of electric signals for maintaining synchronous operation of apparatus, e.g. in a telegraph system, (a) a thermionic valve may be provided for eliminating impulses in one direction, (b) one or more relays may be provided for suppressing half of the impulses corresponding to each signal, and (c) the arrangement may be such that phase correction in either direction is effected without sensibly affecting speed. (a) Fig. 1 shows an arangement for running a shunt-wound motor M in synchronism with unit signals of the Morse code. Square-topped signals are available at terminals A, connected in circuit with the primary winding T<1> of a transformer or coupled circuit associated with a resistance R<1> and a condenser C<1>. The secondary winding T<2> with its condenser C<2> is connected to the filament F and grid G of a thermionic valve in circuit with a battery e. The plate circuit of the valve includes a battery B and leads g<1>, g<2> to a reversing switch S continuously operated by the motor M. Leads h<1>, h<2> from the switch S pass to a resistance R<3> and an auxiliary field winding F<2> of the motor with an associated condenser C<3>. Fig. 2 represents the electrical conditions as functions of time at different parts of the system. The sudden changes of E.M.F. represented in the line a. showing the Morse signals, act on the transformer primary T<1> to produce transient voltage impulses in the secondary T<2> represented by line b. Of these the valve G suppresses the negative impulses, leaving only the positive impulses in the plate circuit as represented by line c. When the synchronizing action is operative, the switch S is rotated at a rate corresponding to two reversals within the time duration of a dot, and the impulses impressed on the field winding F<2> are as represented by the line d. If the motor speed is increased slightly, these impulses are of the type represented by the line e and the resultant field of the motor is modified to cause a slower running of the motor. A correction in the opposite sense is effected when the motor is running too slowly. (b) Figs. 5 and 6 show arrangements applicable to the production from attenuated double-current Morse signals received at terminals A of impulses at terminals C corresponding to those of line c, Fig. 2. In the arrangement of Fig. 5, the tongue 9 of relay 8 connected to terminals A has a marking oias and moves between contacts 10, 11 in the circuit of a battery 12, of which the middle point is connected to one terminal B while the tongue is connected through a condenser 15 to the other terminal B. Impulses .corresponding to those of line b, Fig 2, are thus available at terminals B. These terminals are .connected to the coil of a relay 16 of which the tongue 17 is given a spacing bias and moves between a blank contact 19 and a contact 18 con- .nected to one terminal C while the tongue 17 is connected through a battery 22 to the other terminal C. The relay 16 thus serves to suppress the impulses in one direction. In the arrangement of Fig. 6, the tongue 24 of relay 23 has a ,marking bias and moves between a blank contact 25 and a contact 26 connected through a battery 27 and lead 28 to a relay tongue 30, of which the back contact 32 is connected to one terminal C. The tongue 24 is connected to the other terminal C by a lead 29, and the leads 28, 29 are crossconnected through a resistance 35 and the coil of a magnet 31 controlling the tongue 30, and a condenser 36 is connected around the magnet. When the tongue 24 comes against contact 26, the magnet 31 is energized slowly so that unidirectional impulses corresponding e.g. to the beginnings of signals become available at terminals C. (c) Fig. 7 shows means for correcting phase without sensibly affecting speed, for utilizing the integral of the phase corrections to correct the speed of the motor permanently, and for reconstituting deformed cable code signals for retransmission. The tongue 43 of the relay 42 at the receiving end of the cable 37 moves between contacts 44, 45 in the circuit of a battery 46, 47, of which the middle point is connected through - coils of relays 52, 51 to the tongue 43. The tongue 53 of relay 52 moves between contacts 54, 55, which are connected together and are in circuit with a battery 57<1> connected to the tongue 53 and with apparatus 57 comprising the arrangement of Fig. 6. One-way impulses corresponding to the beginnings of line signals are thus available at the ends of leads 58, 59 which are each connected to one half of a divided slip ring 60 on a shaft 64 driven from the shaft 64<1> of a phonic motor 66 through the differential gearing shown. Adjustable brushes 61, 62 bearing on the ring 60 are arranged in circuit with a relay 63, of which the tongue 80 moves between contacts 79, 79<1> to complete circuits for effecting the actuation of one or other of two oppositely disposed ratchet wheels 72, 73 on a shaft 71. A gear 70 on this shaft serves to rotate the idler gear 69 of the differential gearing to apply a phase correction in the connection of the motor 66 to the slip ring 60. The motor 66 is driven by a reed 91, and the integral of the phase corrections made may be utilized to vary the rate of vibration of the reed to correct the speed of the motor permanently. For this purpose, a spring 90 on the end of the reed is engage'd between pins 89 on a sliding block 87, the position of which is controlled by a screwed shaft 86 operated from the shaft 71 through gearing 84, 85. Alternatively the phase correction may be effected through a reversing clutch controlling motion derived from a continuously rotating shaft, or the differential gearing may be omitted, the shaft 64 being driven directly by a phonic motor, and phase being corrected by controlling the phase of the impulses driving this motor. These impulses are derived from a battery in circuit with contacts which are opened and closed by a cam on the shaft of a second phonic motor, and the member carrying the contacts is rotatable by the gear 70 to correct phase. For reconstituting and retransmitting the deformed signals, the tongue 106 of the relay 51 moves between contacts 107, 108 connected respectively through the coils of magnets 114, 115 with a battery 109 connected to the tongue 106. The armatures 116, 119 of these magnets serve to move selector pieces 117, 120 respectively into positions in which, when acted on by cams 130, 131 on the shaft 64, they actuate keys 122, 126 for transmission of the signals in cable code over a second cable 136. Specification 196,971 is referred to.