Patent GB-239253-A (GB)
Title: Telegraph repeater
IPC: H04L25/46
Filed: 1924-04-30
Abstract: 239,253. Angel, H., and Western Union Telegraph Co. April 30, 1924. Restoring or modifying imperfect signals; repeating systems using contact-making relays; synchronous movements.-In a synchronized telegraph retransmitting system with means for regenerating the received signals prior to their retransmission, a single member maintained in vibration by the direct action of the received signal impulses controls the retransmission. Fig. 1 shows an arrangement suitable for a land line repeater station. Signal impulses from the receiving relay ML of either a simplex line SL or a duplex line DL, according to the position of a switch 5, pass to earth through the coils of a relay FCR and through one of a pair of coils of a relay OR. A fork F controlling the retransmission by a relay RR over the outgoing line RL is maintained in vibration by impulses through an electromagnet FM connected to - battery and to the marking contact of the relay FCR of which the tongue a<1> is connected to + battery with the interposition of a condenser K, and the spacing contact is connected to + battery through a resistance R. The natural frequency of the fork is adjusted by mean of weights w or a spring t so that each tine completes its movements in both directions during a signal impulse period. Thus the tine f during this period makes contact at c and at c<1>. The mid-point of a potentiometer P is connected to the fork with the interposition of a condenser K<1> and to the contact c<1> through the second coil of the relay OR of which the spacing and marking contacts, are connected to + and - battery respectively, and the tongue is connected to the contact c through the coil of the relay RR. The arrangement is such that the discharge of the condenser K<1> through the second coil of the relay OR occurs at a time and in a direction to assist the movement of the armature upon a reversal of the signal current. The phase of the fork's vibration may be varied by adjustment of the condenser K. A recorder DW may be arranged in the circuit of the relay RR to produce a local record of the regenerated signals. Fig. 2 shows a modification suitable for a cable system using code elements of +, -, and zero potential. The movements of the tongue N of the receiving relay control in the usual manner the energizing of the dot relay R' and the dash relay R<2>, and these control respectively relays FCR<1> and FCR<2> controlling the fork F'. The fork is connected to the mid-point of a potentiometer P<2>, and the tine f<1> engages a contact c<2> connected to the marking contacts of the relays R' and R<2> through the main coils in series of relays RR<1> and RR<2> for repeating dots and dashes respectively into the outgoing line L<2>. The armatures of the relays RR<1>, RR<2> remain on their marking contacts until a signal of opposite polarity or a code element of zero potential is received. In the latter case a circuit is closed through the spacing contacts of the relays R<1> and R<2>, and auxiliary coils SC<1>, SO<2> in series of the relays RR<1> and RR<2> upon engagement of a contact c<3> by a contact c<4> carried by and insulated from the tine f<2> of the fork.