Patent GB-346434-A (GB)
Title: Improvements in or relating to electric telegraph systems
IPC: H04L5/18
Filed: 1930-01-09
Abstract: 346,434. Multiple type-printing telegraphy. ELECTRICAL RESEARCH PRODUCTS, Inc., 195, Broadway, New York, U.S.A.-(Assignees of Clokey, A. A.; 27, Sunderland Avenue, Rutherford, New Jersey, U.S.A.) Jan. 9, 1930, No. 853. Convention date, March 7, 1929. [Class 40 (iii).] In a 5-unit code distributer system with periodic reversal of the direction of traffic, the west terminal WT has 8-channel land-line communication with a west repeating station WR, Fig. 1, which repeats through a cable of a mid-cable repeating station CR. The latter repeats to an east repeating station ER, Fig. 2, where the messages are recorded on perforated tape and retransmitted over two duplex 4-channel land-lines through an cast intermediate repeating station EIR to east terminal ET. In the high-speed section, WT to ER, the traffic is simplex and is reversed at intervals by separate timing cams located at WT, CR, ER. In the low-speed section, ER to ET, the line is provided with duplex circuits but transmitters and receivers are cut in alternately, in accordance with the direction of the traffic under the control at ER of a timing-cam 1922 which effects reversal throughout the section by applying d.c. potential to a pilot-line 1936. The high-speed section is synchronized by the message impulses with a master fork at the sending end. The low-speed terminals are synchronized with an independent fork at ER by synchronizing impulses sent over the pilot-line 1936, tape checks being provided to stop the retransmitters momentarily when they overtake the supply of tape from their associated receivers. The intermediate repeating stations WR and E1R operate bv relays without distributors. The mid-cable station CR has a monitoring printer which takes a local record of the messages, and a floating transmitter by means of which a local " out " message can be sent over a selected channel, the " through " message of that channel being suppressed. The system includes signal-shaping networks, thermionic amplifiers and impulse-lengthening systems, and arrangements for synchronizing, for phasing, and for reinserting impulses lost in transmission. Distributer systems. The 8- channel west-to-east signals received at station ER are distributed to two perforators, one of which deals with the odd and the other with the even channels. The "in" signals, after being shaped and amplified, are passed to vibrator relays (1616, 1617, Fig. 16, not shown), which reinsert lost impulses and control a receiver relay (1618, Fig. 16, not shown) which has its contacts so connected that it converts + and - impulses intc + and zero impulses respectively in the odd channels, and into zero and + impulses respectively in the even channels Since the polarities of marking and spacing impulses are re versed in alternate channels ir the incoming 8-channel circuit the + and O impulses produced as above conform to the normal code. To this end, the rocking armature of the said receiver relay is connected to +, while its back and front contacts are connected through wires 1618a, 1618b, Fig. 17, to alternate segments of ring 1712, each segment being devoted to a different channel. The impulses pass to impulse-lengthening valves 1715 whose grids are insulated by condensers, so that anode currents continue to flow through perforator magnets 1727 until cancelled by the application of negative grid-potential from ring 1713 through the lagging auxiliary brush 1756. The tapes thus perforated are passed through tape checks 1732, one for each channel, to transmitters controlled by two 4- channel distributers (Fig. 18, not shown) and so to the apices of two duplex bridges 2112, 2113, Fig. 2. In each of these 4-channel lines the polarities of marking signals alternate in successive channels, the printing magnets in the receivers being connected to battery terminals of correspondingly alternating polarity. The distributers earth the line between impulses. Further circuit details are described below. Synchronous movements: circuits. The distributers at stations WT, CR, ER in the high-speed section are synchronized by corrector mechanism of the kind shown at 521, 532, Fig. 5, which is controlled by the insignal impulses. The distributors at ER, ET in the low-speed section are synchronized from an independent fork 1933, Fig. 2 (Fig. 19, not shown), which is located at ER and drives the local low-speed motor 1932 and also transmits synchronizing impulses over the pilot line 1936 to the motor 2218, Fig. 22A, at station ET, the latter impulses being passed through a transformer 2225 and relay 2229 to alternate pairs of magnets 2230, 2231, Fig. 22A. The distributer shaft at WT runs fast, and the corrector mechanism at each station is set for forward or backward correction as required. Synchronous movements: corrector mechanism. " In " signal impulses at WT are, during eastwest traffic, applied to the synchronizing relay 519, Fig. 5, via a thermionic amplifier and an electro-magnetic relay (619, 629, Fig. 6, not shown) and the wires 629a, Fig. 5. The armature 518a rocks at each change of polarity of the signals, so that condenser 529 discharges periodically over wire 518b and correcting-distributer 812, 813, Fig. 8. If synchronism obtains, the discharge passes through one of the earthed segments of the distributor, but in the absence of synchronism the discharge passes via wire 813a to right - hand winding of magnet 519, whose armature thereupon gives earth to the corrector magnet 523 if the switch 531 be set as shown, this switch serving to bring in one or other of the corrector magnets 523, 524, according as backward or forward correction is desired. During the change-over in the direction of traffic, correcting impulses are applied by a cam to the corrector magnet 523 or 524. Similar correctors are provided at stations CR, ER. Phasing arrangements. To enable the distributers at station CR to be correctly phased, phasing-lamps 1001, Fig. 10, at that station are substituted, by means of switch 1026, for the magnets of the local monitoring printers 1018. In the absence of tape, the signals emitted, Fig. 7, by the transmitter at WT, are positive and negative in alternate channels, the polarities of the marking and of the spacing currents being reversed in adjacent channels. The lamps 1001 consequently light up in groups of five, indicating the phase of the receiving distributer ; and to enable the channels to be identified, the first two channels have their middle transmitter-contacts connected to reversed polarities at contacts 747 of phasing-switch 745, Fig. 7. Phasing-lamps are provided at stations WT, ER, ET also, and phasing transmitterswitches, similar to 745, are provided at ER, ET. The phases are adjusted by hand during a series of trial reversals of the direction of traffic, synchronism being controlled from the sending end; and the synchronism-correcting distributer-rings and brushes are adjusted to allow for line-lag. Reversing direction of traffic: circuit system. The direction of transmission is reversed from time to time under the control of timing cams which are driven independently from the distributer shafts at stations WT, CR, ER, and bring about the necessary circuit changes, partly by direct operation of contacts and partly through transfer relays. The transfer cam system is indicated at 314, 319, 1214, 1224, 1922, Figs. 1 and 2, and the transfer relays at 614, 620, 1518, 1620, 2216, 2219 .. 2222, 2217 ; details of the circuits are illustrated in other Figures not shown. The transfer relay 614 at station WR is controlled from station WT by d.c. over the pilot line 330 and those at E1R and ET are controlled from station ER by d.c. over the pilot line 1936. Reversing direction of traffic ; timing-cam system. At station WT, the transfer is effected when cams 815, 816, 817 all close their contacts together; of these, 817 makes a brief contact four times a minute and 816 a longer contact once a minute, while 815 is a selected member of a group of cams each capable of determining a duration of a given number of minutes. In effecting a reversal of traffic, these cams co-operate to connect earth via wire 826a to motor 324, which tends to drive the transfer-cam-shaft 323 through the friction clutch 325; and cams 815, 816, 817 also momentarily connect earth via wire 826b to the point y, Fig. 3, and so to the escapement magnet 327 via contacts of cam 316 and either the receiving distributer (433, Fig. 4, not shown) or the transmitting distributer 724, Fig. 7, according as cam 316 is set for east-west or west-east traffic. (These distributers are connected to wire 327a in parallel. The escapement magnet 327 allows the shaft 323 to turn through one step, whereupon the cam 321 connects point y to earth as an alternative to the momentary earth on line 826b. Thereafter the magnet 327 is intermittently earthed from 321 via the point y and the receiving or the sending distributer and wire 327a ; it thus turns the transfer-cam-shaft through half a revolution and the contacts controlled by transfer cams 314 .. 319 effect the necessary circuit changes for reversing the traffic. During the rotation of the cams, the impulse-sender 320 applies a predetermined number of impulses via wire 320a, Figs. 3 and 5, to the synchronism-correcting magnet 523, so as to compensate approximately for any loss of synchronism which would otherwise occur during the process of transfer. Tape-feed circuits. When station WT is changing over from sending to receiving, the tape-feed magnets 737 .. are operated and locked through the differentially wound relays 729 .. The right-and left-hand windings of relay 729 are connected in parallel to magnet 737 and earthed battery on one side and via segments 722 and switch 745 to earth on the other, the path for the left-hand winding being direct while that for the righthand winding passes via wire 722b, cam switc