Patent GB-196980-A (GB)
Title: Improvements in or relating to synchronous telegraphic systems
IPC: H04L25/42
Filed: 1922-01-27
Abstract: 196,980. Western Union Telegraph Co., and Foll, J. V. Jan. 27, 1922. Repeating systems using contactmaking relays; restoring or modifying imperfect signals.-In systems -of cable or wireless telegraphy employing synchronous transmitters and receivers, the signal impulses at the receiving or retransmitting station are reproduced in a strengthened and correctly-defined form, and are made of predetermined adjustable length, by means of a distributor and arrangements of relays. Signal impulses received alternately or successively from two or more cables may be retransmitted into a single cable, and vice versa. In the arrangement shown in Fig. 1, impulses received over the positive dot relay F, and the negative or dash relay F<1> are retransmitted into a cable X, or are recorded. The distributor may be fitted with a receiving ring C, a sending or locking ring D, and a clearing ring E, with their respective collecting rings and brushes c, c<1>, d, d<1>, and e, e<1>. Two sets of relays G, G', and G<2>, G<3> between the distributor and the sending on or regenerating relays H, H<1> are shown, and are supplied with signal impulses alternately; but only one set, or more than two sets, of intermediate relays may be used. The distributor rings C, D are fitted with ten, and the ring E with five segments for each signalling time unit. Pairs of segments on the ring C at intervals of a time unit are connected up alternately at c<2>, c<3> to the respective relays G, G<1> and G<2>, G<3>. The locking ring D is shown with eight segments for each time unit alternately connected up at d<2>, d<3>; the eight segments correspond to a retransmitted signal impulse having a length 80 per cent of that of the received impulse, but a different number of segments may be so employed to give a different proportional length. On the ring E, the alternate fifth segments are connected up together, the other segments being idle. Each of the relays G, G<1> and G<2>, G<3> has biasing or spacing coils g, through which a comparatively weak constant current passes, self-locking coils g<1>, pick-up coils g<2>, and clearing coils g<3>. When the relay F is closed by a positive or dot impulse, a circuit is completed from the positive side of battery K, through ring c, brush c<1> and connection c<2>, or c<3> to coils g<2> of relay G, G<1> or G<2>, G<3>. The positive contact G or G<2> is thereby closed, completing a circuit through the self-locking coils g<1> and battery K, and making another circuit whereby the operating coils h<1> of the sending-on relays H, H<1> are connected to the battery K through the eight interconnected segments of the locking ring D. A positive impulse is thus sent into the cable X or the recorder so long as the brush d<1> is passing over the eight segments. The parts are returned to normal position by the brush e<1> closing the circuit of the clearing coils g<3>. Similarly, when the relay F<1> is closed by a negative or dash impulse, a negative impulse is sent into the cable X or the recorder. The clearing ring E may be adjustable relatively to the locking ring D to give a fine adjustment of the lergth of the transmitted signal impulse. Fig. 2 shows an arrangement for retransmitting signal impulses received over relays F<2>, F<3> respectively from two separate cables A and B to a single cable X. The combined selecting and locking rings C' and C<2> for the cables A and B respectively are connected through relays G, G<1> and G<2>, G<3> to the sending ring M, which transmits an impulse from each cable alternately to the sending relays H, H'. No clearing ring is employed. When, say, a positive or dot impulse is received by the drum relay F<2> over cable A, the contact f<1> is closed and the coils g<4> of the relay G, G<1> are energized over the connection c<2> and spaced pairs of segments on ring C<1>, the circuit remaining closed while the brush c<1> passes oversuch of the intermediate or locking segments asare. connected at c<4>. The positive contact G isthus closed, and a positive impulse is sent to cable X by the energization of the operating coils h<1> of the sending-on relays H, H<1> through the sending ring M. In an arrangement for transmitting signals received from a single cable alternately to one or other of a pair of cables, the distributor is fitted onlv with two combined selecting and locking rings, by which the received' impulses are directed alternately, over relays corresponding to G, G' and G<2>, G<3>, to one or other cable through one or other of two pairs of sending-on relays. According to the Provisional Specification, one group of segments of the locking ring may be connected up to a transmitterswitch to give synchronising impulses when signals are not being sent.