GB359448A - Improvements in call metering in telephone systems - Google Patents

Abstract

359,448. Automatic exchange systems. TELEFONAKTIEBOLAGET L. M. ERICSSON, 33, Kungsgatan, Stockholm. June 18, 1930, No. 18655. Convention date, June 21, 1929. [Class 40 (iv).] A zone-metering arrangement comprises impulse senders associated with each junction or each group of junctions and adapted to transmit, to the meter, impulses corresponding to the charges for the various junctions, the senders of a number of junctions used in a connection being started up in turn, commencing with the final junction in the chain, by a special impulse of longer duration or of alternating current. The sets of impulses are repeated throughout the conversation. The Figure shows only the third wire circuits used in an established connection, C2, C3 being third wires of interexchange junctions. When the called party responds, a cam TS periodically short-circuits relay R2, the impulses being of relatively long duration. Each relapse of R2 completes, at the final exchange, a circuit for stepping magnet AM over interrupter PS and also for magnet RM which brings a stepping pawl DH, pivoted to armature SA, into engagement with ratchet wheel SH. Magnet RM also sends a short-circuiting impulse to R4 over springs K3, but this is of short duration since, after a few steps of SH, cam RS permits springs K3 to open. As the pulse to AM is long, SH is stepped around until pin S closes contacts 3 so that magnet SM of sender IS1 receives an impulse from PS. Magnet SM drives a shaft carrying cams HS, SS, of which HS maintains the circuit of SM over K1 and SS sends back three impulses to short-circuit R4. The initial impulse to R4 and the first two impulses from SS are of short duration and merely repeated by RM at the intermediate exchange to R6 to operate the meter SR without starting the sender IS2, the ratchet wheel SH being restored to normal by a spring after each impulse. The third impulse from SS is, however, of long duration and starts up IS2 to send an additional series of impulses corresponding to its associated junction.