Patent GB-221556-A (GB)
Title: Improvements in or relating to apparatus for use in quadruplex telegraphy
IPC: H04L5/04
Filed: 1923-06-11
Abstract: 221,556. Creed & Co., Ltd., Creed, F. G., and Willson, E. A. June 11, 1923. Diplex and quadruplex telegraphs.-In a diplex or quadruplex system based on simultaneous single-current and double-current transmissions, the current-reversing key mechanism at the A side of a transmission station and the current increment and decrement key mechanism at the side of the same station and the corresponding receiving device at the B side of the other station are so constructed and arranged to operate together under the control of Wheatetone or other transmitters as to eliminate the " B kick " and allow of transmission to the B side of the receiving station as rapidly as to the A side, thus enabling the signals received on the B side of the receiving station to operate an automatic receiver similarly to those on the A side. Fig. 1 shows the arrangement at one station for quadruplex working. The A side or reversing key mechanism comprises a lever 1 mounted to work between a stationary contact a and a movable contact b carried by the tongue e of a relay E operated from an automatic transmitter H, a spring d tending to hold the lever 1 against the contact a. The B side or increment key mechanism comprises two levers 2, 3 each mounted to work between a stationary contact o or r and a movable contact p or s, the contacts p and s, insulated from each other, being carried by the tongue u of a relay F operated from a second automatic transmitter I, springs w, x tending to hold the levers 2, 3 against the contacts o, r 'respectively. The contacts a, b are connected as shown to the levers 3, 2 respectively, the contact p is connected through a resistance p<2> to the negative pole m<3> of a battery m, and the contact r is connected through a resistance r<2> to the positive pole! n<1> of a battery n, the other poles of these batteries being earthed at t. The contacts o and s are connected through resistances o<2>, s<2> to points m<1>, n<3> in the batteriesm, n respectively, such that one-third of the battery is included in each case between this point and the earthed terminal. The lever 1 is connected to the line f and artificial line f<1> through the leads g and through the coils of a non- polarized relay D and a polarized relay C for controlling the B side and A side receivers 9, 13 respectively at the same station. The arrangement is such that a pole of either battery isconnected to the line f at the moment when a. pole of the other battery is disconnected therefrom, thus reducing to a minimum the time during which no current flows to line. This results in a considerable reduction of the B kick, and complete elimination is effected by arranging the tongue h of the relay D at the other station to work between contacts i, j to control a high-speed polarized relay G which operates the receiver 9 through the connections shown. The relays E, F, G may be of the kind described in Specification 172,717*, [Class 38 (v), Electric switches &c.]. Perforated-strip transmitters.-In a modified transmitting arrangement, Fig. 2, the relays E,. F are eliminated and the tongues e, u each replaced by a lever 32 pivoted at 32<a> and operated mechanically from the transmitter. The lever 32 is connected by a rod 31 to an eccentric 30 on a shaft 27 driven through a friction clutch and controlled through an escapement device with a tooth 26<a> engaged by the forked end of an arm 25 carried by a lever 20 corresponding to the usual contact lever in a Wheatstone transmitter. The transmitters H, I are driven at the samespeed or at suitable relative speeds. Specification 235,300, [Class 38 (v) Electric switches &c.], also is referred to.