Patent GB-443986-A (GB)
Title: Improvements in or relating to manual exchanges for use with teleprinting systems
IPC: H04L12/04
Filed: 1935-01-01
Abstract: 443,986. Telegraph exchange systems. SIEMENS & HALSKE AKT.-GES., Siemensstadt, Berlin. Jan. 1, 1935, No. 82. Convention date, Jan. 31, 1934. [Class 40 (iii)] Supervisory signals are given by sending impulse combinations corresponding to predetermined pairs of characters, particularly in a system in which a trunk line is allocated by a manualexchange operator or in which audio - frequency lines have to be connected to directcurrent lines. Relays in the one-way cord circuits at the exchange control means for indicating the origin of the supervisory signals. Lay-out of exchange system.-The invention is described as applied to a system, Fig. 1 (not shown), in which a manual exchange is connected to an automatic telegraph exchange for subscribers using D.C. signals and to a telephone exchange for subscribers using both telephonic and audio-frequency telegraphic communication. The Figure shows a connection at the manual exchange between a telephonic and audio-frequency telegraphic trunk FSL and a D.C. trunk FTL. Audio-frequency signals arriving at the jack FKL are converted to D.C. signals by the repeater US located in the operators cord circuit, and the converse operation is effected by the repeater US for signals travelling in the opposite direction. The operator has a receiving relay C, D, in each direction of traffic, and the corresponding contacts c, d, operate his printer relay EM. He also has a transmitting contact a, b, in each direction of traffic, and these contacts are controlled by his transmitter contact sk. Supervisory signals. These are given by lamp LW for signals travelling in the direction of the arrow W and by lamp LO for signals in the direction O. When the clearing signal is given, signals denoting a particular pair of characters are sent and are passed on by relay C or relay D, as the case may be, to the magnet EM of the operator's printer. The type-bars corresponding to the pair of characters in question are modified, Fig. 3 (not shown), so that they may operate the pair of contacts K1, K3, besides typing the characters which they bear. Through contact Kl the sluggish relay Z is energized and prepares at z a circuit through contact K3. Meanwhile slow-release relay W has pulled up through contact c, and consequently relay SW pulls up through contact w2, holding on through its winding II and contact sw2, while it lights the clearing lamp LW through sw1. Similarly if a clearing signal is given in the O channel the contacts K1, K3 are again closed, but the lamp is lighted by means of hold-on relay SO. The origin of the signal can be detected by opening the distinguishing- key LTO or LTW to break the circuit of the energized relay SW or SO. A flicker signal is similarly sent by a different pair of impulsecombinations which select the key contacts K1, K2 and cause the relay FLW or FLO to pull up and hold on. Windings I, II and corresponding contacts 1, 2, are so arranged that when this occurs the circuit of the lamp LW or LO is intermittently interrupted. The arrangement may be such that the impulse combination has to be repeated a number of times before the indicator circuits respond. The signals may be received from a startstop repeater.