GB345787A - Improvements relating to telephone systems - Google Patents

Abstract

345,787. Automatic exchange systems. SIEMENS BROS. & CO., Ltd., Caxton House, Tothill Street, and ESCOTT, A. J., 51, Redbridge Lane, Wanstead, both in London. Feb. 27, 1930, No. 6542. [Class 40 (iv).] A system in which the number of metering impulses varies with the time of day is so arranged that a change in tariff has no effect on metering operations which are taking place at the instant of change. If metering is also dependent on the zone of the wanted party, the same impulse transmitter which transmits, say, three impulses for calls to one zone at one time of day is used also to transmit the same number of impulses for calls to a different zone at a different time of day. The Figure shows common metering apparatus associated with a first code selector at which the zone of the wanted party is determined by an additional vertical wiper VM. When the called party replies relay D (not shown) connects up the left-hand winding of relay DA to cam S. Relay DA operates at the next connection of battery at cam S and locks up temporarily over its centre winding. Shortly afterwards, relay DB operates over cam Z and locks until the end of the connection but relay DA is only held for the period of closure of cam Z and during this period one or more metering impulses are transmitted over wiper VM and lead M. For local calls (levels 1-4, 7-10) one impulse only is sent at all times of day. For calls to zone 1 (level 3) two, three, or four impulses from interrupter 11, 12, or 13, are sent according to the condition of relays X, Y which are controlled through relays A, B by a clock-arm W. Similarly for calls to zone 2 (level 6) three, four, or five impulses are transmitted by interrupters 12, 13, 14. A relay SP operated temporarily over cam S at the beginning of each metering cycle so controls the circuits of relays X, Y that they are only able to change their condition at the times when SP is operated.