Patent GB-126498-A (GB)
Title: Improvements in or relating to Multiplex Telegraphy.
Inventor: MACKENZIE FRANCIS JAMES
IPC: H04L5/22
Filed: 1918-05-24
Abstract: 126,498. McKenzie, F. J. May 24, 1918. Multiplex telegraphs; synchronous movements; type-printing telegrophs.-The distributor at each station of a multiplex type-printing telegraph system comprises a series of relays which are successively energized, the energization of one relay serving to prepare the circuit of the succeeding relay and to de-energize the preceding relay, while the prepared circuit is closed by a vibrating reed forming part of a switch. Synchronism between the vibrating reeds at the transmitting and receiving stations is obtained by supplying correcting impulses to the reed at the receiving station, these impulses controlling a polarized relay in the line circuit and positive and negative impulses are sent during the non-signalling periods to ensure synchronism during these periods. Distributor. The distributor D at the transmitting station A comprises a series of relays 8 provided with operating windings 13, 14, 15, and 16 and resetting windings 17, 18, 19, and 20. The operating windings are connected alternately to leads 6 and 7, and the resetting winding of a preceding relay is connected in series with the operating winding of a succeeding relay by the operation of the intermediate relay. The operating and resetting windings are earthed through contact blocks 27, brushes 28, and relay windings 25 having armatures 26 adapted to engage contacts 29 to earth the leads 31 connected to the keys 30. The relays 25 may be dispensed with and the armatures 26 operated by the relays 8. The leads 6 and 7 are adapted to be connected alternately to an earthed battery B' by means of a vibrating reed 1 engaging contacts 4 and 5. The first and fourth keys 30 of the transmitters T, T', &c. are connected, when not depressed, to the negative side of the battery B<2>, and the remaining keys are connected, when not depressed, to the positive side of the battery B<3>, in order that synchronizing currents may be transmitted during the non- signalling periods. The distributor at the receiving station is similar in construction to that at the transmitting station and the receiving station is provided with a polarized relay 43, the armature 44 of which is adapted to connect an earthed battery B<4> to the terminal leads of the setting magnets P, P<1>, &c The receiving station is also provided with a vibrating reed 50 controlling the circuits of the distributor relays and a polarized correcting relay 55, the armature 56 of which controls a circuit containing a battery, the operating windings 53 and 54 of the reed 50, and a condenser 61. Synchronizing. The contacts 57 and 58 of the reed 50 are arranged so that, as soon ais the reed leaves its middle position, it engages one or the other of these contacts which move with the reed, which is adjusted to vibrate at approximately the same rate as that of the reed 1 at the transmitting station. When the reeds 1 and 50 are in synchronism, the reed 50 should attain its remotest position from its middle position at the moment when the armature 56 of the relay 55 changes the circuit connexions of the windings 53 and 54. If the reed 50 be losing and moving upwards after engaging the contact 58, when the armature 56 leaves its contact 60 and engages its contact 59, the condenser 61 is charged through the winding 54 and the reed 50 is accelerated. If the reed 50 be gaining and moving downwards when the armature 50 engages its contact 59, the winding 54 is energized to attract the reed 50 and retard its downward movement. A similar correction is obtained when the reed 50 is moving downwards, the energy being obtained from the discharge of the condenser 61. To ensure synchronism between the reeds 1 and 50 during the non-signalling periods, positive and negative impulses are sent during these periods to operate the relay 55.