Patent GB-759684-A (GB)
Title: Improvements in and relating to switching devices
Inventor: LEVY MAURICE MOISE
IPC: H04J3/00
Filed: 1950-09-22
Abstract: 759,684. Automatic exchange systems. GENERAL ELECTRIC CO., Ltd. Aug. 31, 1951 [Sept. 22, 1950], No. 23343/50. Class 40 (4). [Also in Group XL (c)] A system for connecting an input to one of m x n x . . . outlets in accordance with a corresponding set of m+ n + . . . characteristic control voltages applied to the input comprises a first bank of m gates one of which is opened by one of the m control voltages to pass the remaining voltages to a second bank of n gates one of which is opened by one of the n control voltages and so on. In one embodiment, Fig. 10, the voltages consist of pulses in a recurring cycle of pulse positions the first 10 pulse positions MP0 . . . MP9 corresponding to the 10 thousands digits of the wanted outlets the next 10 positions CP0 . . . CP1 to the 10 hundreds digits and so on. After the 40 pulse positions thus used a further pulse position CLP is used for a restoring pulse. If the digit switches S1 . . . S4 are set respectively to positions 4, 6, 3, 7, the pulses MP4, CP6, DP3 and UP7 are fed in succession to the gates M0 . . . M9. The pulse MP4 is accepted only by the gate M4 whose terminal MP4 is connected to the corresponding terminal of the pulse generator 56. The gate M4 is thereby opened and passes the pulses CP6, DP3, UP7, to the gates C0 . . . C9. Gate C6 is opened by pulse CP6 and similarly gates D3 and U7 are opened by pulses DP3, UP7 thereby establishing a connection between the input terminal IT and the outlet OTU7. Pulse CLP restores all the gates to normal at the end of the pulse cycle. Alternatively once the gates are open they may be kept open to pass speech. It may be necessary as described in Specification 759,682 for the device to be shared by several sets of selector switches. In that application the gating device is a router serving several sets of register switches and a mechanical switch is arranged to associate the routes with a register for a comparatively long time. Alternatively the router could be associated at regularly recurring intervals with each register in turn by gates opened successively for a period sufficient to allow the transmission of one complete set of M, C, D and U pulses, Figs. 12, 13, 14 (not shown). In a modification of this arrangement, Figs. 15, 16, two sets of selectors (register switches) are provided from pulse generators. No. 1 and No. 2 arranged to provide M, C, D and U pulses distributed in time as shown in Figs. 16a and 16b, respectively. Sets of M, C, D and U pulses from pulse generator No. 1 are admitted in turn through gates SG1 . . . SG2 to the M, C, D, No. 1 gates and similarly pulse sets from generator No. 2 are applied to the M, C, D, No. 2 gates. The outputs of both M, C, D, Nos. 1 and 2 gates are then applied to a common set of U gates fed by U pulses from both pulse generators Nos. 1 and 2. Fig. 16c, 16d, 16e, illustrate the restoring pulses used for the M, C, D, No. 2 gates, the U gates and the M, C, D, No. 1 gates respectively. In an alternative embodiment the control voltages are characterized by frequency rather than by pulse position, each gate being arranged to be opened by a current of a particular frequency whereafter it passes currents of any other frequency, (see Group XL (c)). Specification 759,686 also is referred to in the Provisional Specification.