Patent GB-292281-A (GB)
Title: Improvements in and relating to electric telegraphic systems
IPC: H04L25/04
Filed: 1927-03-31
Abstract: 292,281. Higgitt, H. V., Wood, K. L., Hubble, W. C., and Eastern Telegraph. Co., Ltd. March 31, 1927. Paper-feed for receivers, automatically controlling; perforated strip transmitters; multiplex telegraphs; restoring imperfect signals; repeating- systems using contact-making relays.-Relates to multiplex systems such as that described in Specification 287,229 wherein the speed of signalling is different in different channels, and consists in moving the tape or like record for each channel in an irregular manner so that the signal elements in any one channel, which are unevenly distributed in time, may produce a record comprising signal elements which are evenly distributed in space. Each receiver is cut off from the line except when the tape is moving, and the sending apparatus can at pleasure be put under the control of either a local perforated tape or the signals received from a distant station. In the example illustrated “ of the line time is allotted to a slow channel while ¥ is allotted to a fast channel in which 3 signal elements are sent for every 1 in the slow channel. Receiver. The tape 11 of a siphon recorder 13, Fig. 1, in the faster channel is drawn off by a roller 3 which is carried by an intermittently driven shaft 50. The shaft tends to be driven by a continuously running motor 1 but is held stationary by the armature 7 engaging the notched wheel 5 except when this armature is withdrawn on energization of the magnet 10 through contacts 51 carried by the shaft 6. This shaft rotates synchronously with the signals, so that the circuit 9, 10, 51 is closed by the three contacts 51, and the tape is therefore in motion, during only three signal elements out of four, the remaining element being allotted to the slower channel. Signals from the line 52 are delivered to the recorder 13 only when circuit is made, through the commutator 12, in the non- stationary positions of shaft 50. A stripperforating receiver such as that described in Specification 28952/13 may be similarly adapted for the purpose described. In a modification the required irregular movement may be imparted by means of a Geneva-stop mechanism. Transmitter. At the transmitter the tape 23, Fig. 2, in the faster channel is fed forward by a star-wheel 20 on a shaft 21<a> driven by a spur wheel 21 which is positioned by a jockey 24 and is driven intermittently by the spur wheel 22 which lacks one out of every four teeth 53 and is carried by the uniformly rotating shaft 54. Thus the tape 23 rests for one out of every four signal elements. The cam 25 has three humps 55 which operate simultaneously with the teeth 53 to render effective the signals in the faster channel, as described in Specification 234,179. Thus the humps 55 drive forward the dot and dash hammers 26, 27, which engage or miss the selectors 32, 33 according as the magnets 30, 31, are energized or not when the peckers 28. 29, rise or rest under control of the tape. Re-transmission. The magnets 30, 31, may be associated with switches (not shown) whereby they can be connected either to the local peckers as shown or to the line from a distant station, when the signals received unevenly and retransmitted will alike be distributed in time. Single battery for two channels. Fig. 3 shows an arrangement whereby a single battery 44 can be used for the dot and dash contacts 40, 42 and 41, 43, which send on the regenerated outgoing signals for the faster and slower channels respectively. The tongues 40, 41, 42 in the spacing position are in series with the back stops a so that when any one of them is moved to its front stop b the battery 44 is connected between the line wires 56, 57, through the remaining contacts.