Patent GB-869878-A (GB)
Title: Improvements in or relating to electric gating circuits
Inventor: PEDDLE EDWARD ARTHUR RICHARD
IPC: H04Q11/04
Filed: 1956-11-15
Abstract: 869,878. Automatic exchange systems. GENERAL ELECTRIC CO. Ltd. Nov. 1, 1957 [Nov. 15, 1956], No. 34937/56. Class 40 (4). [Also in Group XL (c)] In an arrangement for detecting the simultaneous presence of pulses on a selected combination of a number of leads, less than the total number of leads, each pulse lead has a control lead associated therewith, and the associated combination of control leads are first selectively marked to produce a change in potential of an output lead, which lead is then only restored to its previous potential if pulses are received simultaneously on the selected combination of leads. In one embodiment, Fig. 2, positive control signals are applied to combinations of leads 2121/1 . . . 2121/16 and these cause the appropriate combination of rectifiers W1 . . . W16 to conduct. Conduction of any one of these rectifiers causes the potential of output lead 2124 to rise to a positive value. Points B1 . . . B16 are connected to positive potential so that rectifiers Z1 . . . Z16 are normally back-biased. A pulse on a lead such as T1 produces a negative pulse in the secondary winding SX1 thereby reducing the potential of point F1. If pulses are applied simultaneously to all of the leads T1 . . . T16 whose associated leads 2121/1 . . . 2121/16 are marked then the potentials of the corresponding points F1 . . . F16 are caused to fall from their previous positive potential to zero and the potential of output lead 2124 likewise falls to zero for the duration of the pulse. In a second embodiment, Fig. 3, the leads 2121/1 . . . 2121/16 are normally at positive potential and with point BX permanently biased positively lead 2124 takes on a positive potential. In the event of a control lead 2121/1 . . . 2121/16 taking on earth potential the associated rectifier W1 . . . W16 conducts and lead 2124 takes on earth potential, at which it remains whilst any of the rectifiers W1 . . . W16 is conducting. A positive pulse on T1, say, backbiases Y1 and raises the potential of point F1 so that W1 no longer conducts. Thus if simultaneous pulses are applied to all of those leads T1 . . . T16 whose associated leads 2121/1 . . . 2121/16 are at zero potential, all the previously conducting rectifiers W1 . . . W16 now fail to conduct and a positive pulse appears on output lead 2124. The invention is applicable to the automatic exchange system described in Specification 856,732 in which leads T1 . . . T16 are connected to the outputs of circulating pulse stores which may carry 100 spaced ¢ Ás.pulses having a repetition time of 100 Ás.,and in which it is desired to determine whether a particular combination of three of these stores contains simultaneous pulses. The particular combination of three of the leads 2121/1 . . . 2121/16 is marked as described above for a duration of 233 Ás. and lead 2124 is examined for a pulse output. To ensure that spurious results are not obtained when no combination of leads 2121/1 . . . 2121/16 is marked the lead 2124 is connected to the pulse detector via a gate which is opened only for a period of 102 Ás. occurring within the 233 Ás. duration of application of the marking combination.