Patent GB-190511685-A (GB)
Title: Improvements in Multiplex Telegraph Systems.
Inventor: GIARA TULLIO
Filed: 1905-06-03
Granted: 1906-07-03
Abstract: 11,685. Giara, T. June 3. Wireless telegraphy. - Relates to multiplex telegraph systems in which several messages may be sent either by wireless telegraphy or over a single line, in both directions at the same time. Methods of synchronizing the distributors and of locking the keyboards of the several stations are described, together with a relay adapted to receive very rapidly following impulses. It is possible further to multiply the number of messages sent at a time by employing harmonic currents with tuned vibrators. Fig. 1 represents two stations A, B with sending-disks 10, 51, and receiving-disks 11, 50. On the disk 10 are a number of sets of sections a, b, c, d, e, f, each set of sections being allotted to a separate keyboard of a typewriting- machine. Two keyboards are indicated at 14, 15, with one key 16,17 drawn in each case. Each key when depressed connects through a battery to ground the corresponding section of its set on the disk, and if the rotating arm 27 is then over the section an impulse is sent through the contact-brush 28, brush 29, and line-wire 30 to the relay 32 at the receiving-station. A local circuit is then closed through the arm 38, contact 39, and the corresponding printing-key 20 of the receiving-instrument 18. The relays 31, 32 are of differential type to permit of duplex telegraphy. In order to prevent an operator from depressing a key except when the revolving arm is within the limits of his set of sections, the keys are normally locked by a detent 40 and released only when the magnet 41 is energized, which occurs when the contact 431 on the revolving arm is over a corresponding segment 43. To secure synchronism, the following arrangements are made : The sending and receiving arms 27, 64 at each station are fast to the same axle 80, driven preferably by an electric motor. Between each set of sections occur contacts 90, engaged by the rotating contact-brush 28, and connected in multiple to the ground through the battery 26. On the receiving- disk 11, instead of a single contact there are two contacts 92, 93 between each set of sections, connected respectively to the magnets 951, 941 and thence to ground. If the rotation of the arm 39 is not exactly synchronous with that of the arm 27, the normal balance due to the simultaneous excitation of the magnets 951, 941 is disturbed, the impulse being received only through one of the contacts 92, 93. The corresponding magnet, acting alone, effects a variation of the resistance 106 of the motor circuit. In this motor circuit is a switch 104 which is closed by the electro-magnet 107 energized by the impulses sent over the line 30. In normal working, these impulses succeed one another with such rapidity that the residual magnetism of the core keeps the switch closed continuously. Provision is made for adjusting the distributors so that they are in the same phase. In the modification for wireless telegraphy, the conductor 291, instead of branching round a duplex relay, enables a simple electro-magnet to be energized and thereby closes the primary circuit of an induction coil, in the secondary of which is included the usual sparkgap. Each time that a transmitting-key is depressed, a signal is emitted by the antenna. Receiving-apparatus of the usual type is associated with the above-described receiving-disk and motor, without, of course, the duplexing-relay. The inner ring x of sets of sections on the transmitting- ring 10 together with the second brush contact 400 on the revolving arm and fixed brush 402, enables this single sending-apparatus to be employed for a second main line (not shown). The receiving-disk 11 is similarly provided with a second ring of contacts. Fig. 6 illustrates a station M with a full complement of sections on its sending and receiving disks, and a substation N having only one section d on its disks. Station M can only transmit to N when the arms 27, 38 are over the sections d, the course of the current being ground, disk 10 (section d), arm 27, duplex relay 31, line 30, switch 601, wire 600, duplex relay 32, ground. The switch 601 is closed by the magnet 607, which is energized as long as the arm 58 is sweeping over the section d. The duplex relay operates the printing-key 20 through the arm 38. A branch circuit 602 enables messages to be sent from N to M at all times, and also provides for synchronizing the various arms. Several diagrams are given showing various ways of connecting " total" stations with "partial" stations by one wire. Fig. 9 shows a number of "partial" stations, three of which can communicate with two stations and four of which are only in communication with one station. Some of the stations may be wireless stations, and use may be made of differently tuned electric waves. Further multiplication may be obtained by the use of vibrating wires as tongues for the duplex relays. These wires will only vibrate for alternating-currents of definite frequencies, and in vibrating each wire 802 opens a fork as shown in Fig. 14, closing contacts 808. Fig. 5 shows a special relay adapted to deal with rapidly succeeding signals. When two impulses follow each other very rapidly, the interval may be insufficient to allow an ordinary relay to reassume the inactive position. The multiple relay shown in Fig. 5 consists of a number of similar elements or relays interposed between the main line 30 and the ground 701. Each element consists of polarized magnets 300 and the armature 301. If an impulse arrives through the contact 305, wire 302, electro-magnet 300, and ground 701, it closes the contacts 308 of the local circuit 307 and at the same time energizes the magnet 309 in a branch circuit, drawing back the armature 303. The contact 305 is in this way broken, but at the same time the armature, now locked, has made the contact 310, and, if this relay element has not restored itself before the next impulse arrives, that impulse will pass through the contact 310, armature 301, contacts 311, 3051, and thence into the second element, which is similar to the first. If necessary, four such elements may be combined.