GB1179079A - Improvements in or relating to Telephone Exchange Systems - Google Patents

Abstract

1,179,079. Automatic exchange systems. SIEMENS A.G. 28 June, 1968 [29 June, 1967], No. 31100/68. Heading H4K. In a telephone exchange circuit comprising a plurality of stores each adapted to store a coded representation of a digit dialled by a different subscriber and a counter or other cyclic circuit driven by an impulse generator, dialling pulse trains taken from the impulse generator are individually interrupted when the output of the stepping circuit coincides with a corresponding stored coded representation. As shown each dialling store Wsp1, Wsp2 &c. is individually seizable by a different subscriber having coded dialling facilities and can store one dialled digit by the simultaneous closing of two out of 5 contacts such as a11 to a15. As an example of operation it is assumed that the stores Wsp1 and Wsp2 are seized by different subscribers during the same cycle. Seizure of a store energizes a relay (not shown) closing a contact such as 1b1 or 2b2. The first of these to close energizes a relay AZ1 in the common equipment ZE. The resulting changeover of contact 3az1 of this relay enables relay AN1 and AN2 in the seized stores and enables a relay AZ2 which in turn enables a relay AZ3. Relay AZ3 disables relay AZ1 allowing the contact 3a Z1 to return to its former condition. The relays AN1 and AN2 have closed contacts 13an1 and an2 and each hold over the corresponding closed pair of two out of five contacts a11 to a15 and a21 to a25 and contacts I to V. Other stores seized after this point have no effect until the following cycle. A pulse generator JG is enabled by closure of a contact 8az 3 of the relay AZ3 and a counter KE commences to cycle from zero count. The counter enables two out of five relays I to V for each count in accordance with the two out of five code. Each relay I to V when enabled opens its contact I to V. As the counter passes through a count corresponding to one of the digits stored in the stores Wsp1 or Wsp2 the corresponding relay AN1 or AN2 in that store is released as none of the paths through a11 to a15 or a21 to a25 and corresponding contacts I to V is complete for that store. Each store has an individual relay J which up to this point repeats the pulses from the generator JG. Thus the relays J in the stores seized during a cycle repeat different numbers of the pulses from the generator JG during that cycle in accordance with the digits entered in those stores. When the last of the energized relays AN1 to ANn releases the relay AZ3 is released re-setting the common equipment and immediately commencing the next cycle.