Patent GB-612921-A (GB)
Title: Improvements relating to telephone systems
IPC: H04Q3/58
Filed: 1946-06-06
Abstract: 612,921. Automatic exchange systems. SIEMENS BROS. & CO., Ltd., and LONG, D. P. June 6, 1946, No. 17229. [Class 40 (iv)] A common control circuit registers as many digits as are necessary to determine the fee area of a call and transmits signals to apparatus in an outgoing junction circuit taken into use by the selector associated with it, to effect a registration therein appropriate to the fee. The common control circuit is released as soon as this has been done and the junction apparatus subsequently controls the operation of the calling party's meter in accordance with the fee area of the called party. The control circuit shown in Figs. 1-2 is designed for use with the type of selector disclosed in Specification 596,752 and the leads extending from the top of the figures connect with those extending to the control circuit from the selector shown in Figs. 1-2 of that Specification. The selector is for use at a satellite exchange and discrimination takes place in the manner described in Specification 596,752, but connection is made to terminal g only for junction calls which do not require metering and for local calls in the X-section. For all other main exchange calls the strapping is to one of the terminals F1-F5, and relay G is then operated after fee-determining pulses have been transmitted to the outgoing relay set. In the case of an outlet group common to two digits a differentiating signal is sent forward as in Specification 596,752. The fee-determining pulses transmitted to the outgoing relay set are complementary in nature, 5 pulses being transmitted for unit rate calls, and 1 pulse for 5 unit rate calls. Contacts in the discriminating arcs ma4, mb5, 6, and mc5, 6 are connected to F1-F5 according to the number of pulses to be transmitted. At the end of the digit which determines the fee area F is operated and brings up the pulse generating relay P which operates as described in Specification 462,773 to transmit positive battery pulses over wire gp1 and the selector test wiper to the outgoing relay set, Fig. 3. The pulses are repeated by a condensercontrolled relay PX to counting relays W, X, Y which operate in the order W; X; Y; Y, W; Y, X and release F to terminate pulse transmission after an appropriate number of pulses according to the terminal over which it was operated. Although a junction to the main exchange is normally seized for every call, local calls may be completed even if all main exchange junctions are busy as described in Specification 596,752. Forced release and statistical metering are also provided. Outgoing junction relay set, Fig. 3. On seizure AA pulls up in the calling loop in series with AX in the control circuit, and is followed by AB, BB, HH and J. The junction is thus busied and the feed bridge is connected up. The impulses transmitted by the caller are received by AA and repeated over the junction by AB, CC coming up for the duration of each digit. The fee-determining pulses over the p wire are received by relay PR and repeated by a condenser-controlled relay XP to counting relays WW, XX, YY, which operate like those in the control circuit to register the pulses. When the selector switches through, AA comes under direct control of the caller's dial and any further impulse trains are repeated over the junction. On the reply of the called party back-bridge relay D operates, followed by M. Relay JA operates intermittently by interaction with J and sends positive metering pulses over the p-wire, further pulses being sent concurrently to the counting relays WW, XX, YY until the chain is saturated, all the relays being operated when the total number of pulses registered is 6, and the operating circuit of JA being opened. Should the called party clear first, D releases but M holds so that an alarm circuit is closed and lamp JL is lit until the incoming loop is opened, whereupon releases takes place as above. Specifications 378,585 and 471,987 also are referred to.