Patent GB-208196-A (GB)
Title: Improvements in telegraph systems
Filed: 1922-08-16
Abstract: 208,196. Western Electric Co., Ltd., (Western Electric Co., Inc.). Aug. 16, 1922. Systems using code elements distinguished by polarity of current; type-printing telegraphs.-In a telegraph-receiving system employing a vibrating relay, the frequency of vibration of the armature is automatically maintained in synchronism with the transmitting mechanism. The receiving distributor is employed for this purpose, and in the arrangement shown in Fig. 1, it has three banks of contacts E, F. G. The main winding 14 of the relay 13 is connected in the output circuit of a vacuum tube or other amplifier V. The continuous ring 22 of the first bank E of the distributor is connected to earth through a resistance 34 and the vibrating winding 15 of the relay 13. The armature of the relay 13 is connected to the continuous rings 24, 26 of the banks F, G. Odd numbered segments of ring 23 and segments 4, 8, 12 of ring 25 are connected to condenser 36; even-numbered segments of ring 23 and segments 2, 6, 10 of ring 25 are connected to condenser 35; whilst the segments of ring 27 are connected to the selecting magnets 29 - - 33 of a printing receiver. When no current is flowing through the main winding 14 of the relay 13, the passage of the brush 20 over the segment 40 of the ring 25 charges condenser 36 negatively from the battery 16, and the vibrating winding 15 of the relay 13 is then connected to the condenser 36 by the passage of brush 19 over segment 1 of the ring 23. The armature of the relay 13 reverses its .position and condenser 35 is charged positively and discharged through the vibrating winding 15 in a similar manner. If the curve O, Fig. 2, represents the form of the received signals in the main winding of relay 13, produced by distortion in the cable from transmitted signals as at A, and H is the form of current in the vibrating winding, the sum of the two, as at C is the form of current actuating the relay, and if the lines M, N indicate the strength of current needed to reverse the armature, the signals actuating the magnets 29 - - 33 will be as at D. This may be made an exact copy of the transmitted signals A by shaping the current curve H by means of suitable values for the condensers 35, 36 and resistance 34, by a condenser shunted about the vibrating winding, and by adjusting its phase relation to curve O by orienting the brushes of the distributor. When a long signal consisting of two successive impulses of the same polarity is received, the resultant' current curve, as shown at d<2>, rises nearly to the value required to reverse the armature, and in order to overcome this defect a portion only of the received signal may be utilized. As shown in Fig. 3, the main winding 55 of the vibrating relay 70 is connected to the middle one of each three segments of the divided ring 69, three segments being equal in length to one segment of the transmitter distributor. The brush arm 61 is shifted with respect to the brush of the transmitting distributor so that the brush 63 passes over the middle segment of each set of three and current passes through the main winding 55 in the centre part of a long signal. For signal elements of ordinary length, the brush 63 causes the main winding 55 of the relay 70 to be energized only by the first portion of each element, but the correct succession of signals continues to be relayed into the receiving mechanism 60 by the current in the winding 56 controlled by the successive discharges of opposite polarity of the condenser 65. Modifications are also described in one of which electromagnetic relays and in another the combination of a condenser and electromagnetic relays, are used in conjunction with the receiving distributor to control the current in the vibrating winding of the relay. The vibrating relay may be a moving coil instrument.