GB680625A - Improvements in arrangements in metering circuits of remote signalling systems - Google Patents

Abstract

680,625. Automatic exchange systems. TELEFON FABRIK AUTOMATIC AKTIESELSKAB, and UNGAR, E. April 20, 1949 [April 21, 1948], No. 10528/49. Class 40 (iv). In a system in which calls are metered in accordance with their duration and the nature of the connection obtained, apparatus is inserted in the metering circuit which receives the pulses normally transmitted at the commencement of a three-minute period and re-transmits them at intervals during the period to the subscriber's meter or to a coin control circuit as the case may be. In this way calls may be made for periods of less than three minutes at a lower charge. As shown, the metering pulses are received on lead Dfi and are repeated by ST to the driving magnet TAVK of a first uniselector TAV. Relay SO comes up for the duration of the train, and SK locks up to ground on B1 followed by SYA. The first two metering pulses received are also repeated by ST over the home contact 25, and contact 1 of bank TAV-b and lead Dfo to the metering circuit. When SO relapses at the end of the train, timed pulses from the source T are extended over bank TAV-d and step a second uniselector TCV at 5-second intervals. The first pulse is also extended over contact 25 of bank TCV-d to step a third uniselector TBV. The contacts of banks TCV-a ... TCV-d are cross-connected to those of bank TAV-c in such manner that during the stepping of TCV a number of the timed pulses equal to one less than the number of metering pulses received by ST are extended to operate SIC either directly or by means of SX. The first operation of SIC steps TBV and brings up SM, which locks up in series with SL when SIC releases, so that subsequent operations of SIC transmit setting pulses over Dfo. As TBV is stepped once at the end of the incoming train and once each time SIC operates, when the number of pulses transmitted over Dfo becomes equal to the number received by ST relay SS pulls up over TBV-a and TAV-a to stop further transmission. SS also releases SK and completes a circuit to home TAV, TBV and TCV in turn and bring up SH, whereupon SS and SH relapse in turn. During its advance when TCV reaches contact 24 the operation of SY releases SYA and TCV is stepped to contact 25 during its release period. Contacts 19 to 24 of bank TAV-d are connected to a second source t which delivers pulses at intervals of 2.5 seconds so that the larger number of pulses required may be retransmitted during a three-minute period.