Patent GB-309388-A (GB)
Title: Improvements in or relating to electric telegraphic receiving and retransmitting or reproducing apparatus
IPC: H04L25/04
Filed: 1927-12-24
Abstract: 309,388. Creed & Co., Ltd., Creed, F. G., and Salmon, R. D. Dec. 24, 1927. Repeating-systems using contact-making relays; restoring imperfect signals; perforated strip recorders; duplex telegraphs.- Relates to regenerative telegraph receivers or retransmitters in which the wave form of the outgoing signals (for recording or for retransmission) is independent of the incoming signals, while the character of the outgoing signals is determined by the character of the middle or least distorted portions of the incoming signals: and consists in devices for reducing the determinative portion of each incoming signal to a minimum fraction of its duration. In the forms shown in the drawings, the invention is embodied with the synchronizing apparatus described in Specification 308,672. Regenerative receiver or retransmitter for use with a multiunit code or land-line morse. The polarized line magnet 15<a>, Fig. 4, controls an escapement and friction clutch 21a, 19, of the kind described in Specification 308,672 in connection with the synchronism control lever 60. The arrangement is such that the plate 19 makes half a revolution when the polarity of the incoming current changes from positive to negative, and the other half of its revolution when the opposite change takes place. An eccentric 18 carried by the plate positions the eccentric-rod 17 accordingly, so that the link 6 occupies an upper or lower position according to the polarity of the incoming current. The output movable contact 9<a> is set against the upper or lower fixed contact 10 or 11 by the abutment member 7 which is moved to the right once per signal period and acts upon the upper or lower bevel 8 if its position (as determined through the rod 17 by the polarity of the incoming current) does not agree with that of the lever. In order that the active period of the member 7 may be brief, (so that only a small middle fraction of the incoming current may determine the sign of the outgoing current) the member 7 is moved, through the lever 5, by a cam 4 on the receiver shaft A, the cam having the form shown in Fig. 2. In a modification (Fig. 1, not shown) the member 7 may be positioned by the magnet armature 14a directly, without the intervention of the escapement mechanism 18, 19. Further (Fig. 3, not shown) the abutment members 7, 8, may both be V-shaped points. Regenerative receivers or retransmitters for use with cable code. In the modification shown in Fig. 10 the polarity of the signals outgoing over line L and earth E from battery 36 through movable contacts 30, 33, is selected by the input positive magnet 40 or negative magnet 41. Thus the magnet 40 when energized acts through the rod 50 to release the clutch and escapement device 49, 44 (which also forms part of the synchronizing mechanism shown at the top of Fig. 10 and described in Specification 308,672) so that the eccentric 53 performs half a revolution, the other half-revolution being completed at the end of the signal. The eccentric-rod 37 thus moves the abutment device 7a downwards, during the signal, so that when this abutment device is moved momentarily to the left by the bell-crank lever 26 (which is actuated at the middle of each signal period by the cam 4 through the double-armed lever 5, 5a, pivoted at 5<x>, it engages the opposite abutment device 8a and turns the bell-crank lever 28 so as to set the contact 30 for a positive outgoing signal. At the end of the signal the contact blade 30 is restored to its upper position by the action of the rod 53<x> on the arm 28<b>, the rod 53<x> being actuated by the cam 4. In this way blocks of signals of like polarity are broken up into individual signals. Negative incoming signals received by the magnet 41 act similarly on the apparatus shown at the right of Fig. 10. Strip-perforating receivers. A land-line morse perforator is shown in Fig. 14. The head 70 is positioned vertically by the rod 17 which is actuated under the control of the received signals as described above. Once during each signal period the head 70 is moved to the right by the lever 5 as already described and so actuates the marking punch 71 or spacing punch 72 to perforate the tape 76. The Specification also describes a modification (Fig. 15, not shown) for use with cable code in which the punches are respectively selected by the dot and dash magnets simultaneously with setting of contacts for the electrical reproduction of the signals. Synchronization of duplex retransmitting systems. Fig. 18 (not shown) indicates a differential duplex system comprising two terminal stations with an intermediate retransmitting station working both ways. The speed is set by one of the terminal stations and the transmitter and receiver are operated from a common shalt at each terminal. At the intermediate station the two retransmitters working in opposite directions are operated from a common shaft whose speed is controlled by one of the retransmitters only, the other being displaced in phase relatively thereto. The construction of an instrument for use with multiple-unit or land-line morse code and comprising a pair of retransmitters working with an adjustable phase difference between them is indicated in Figs. 16, 17 (not shown) and one for use with cable code is indicated Figs. 12 (not shown) and 10.