| 摘要 |
A telephone exchange of the time-division-multiplex type is provided with several synchronized circulating memories whose operating cycle is divided into, say, 100 phases corresponding to respective time slots of a communication frame whereby a multiplicity of conversations can be initiated and carried on simultaneously between calling and responding subscribers. These memories include a caller memory I, a responder memory N, a monitoring memory LP, a counting memory LK, and two ancillary memories LT1, LT2 respectively associated with the caller and the responder. Monitoring memory LP, registering the progress of a call in a corresponding phase thereof, defines up to 10 different states in the establishment of a connection; in the event of a toll call, state No. 10 is followed by either state No. 11 or state No. 12, depending on whether the charge is to be debited to the calling or the called party, wherever a supervisory unit emits a rate pulse. In either case, the counting memory LK registers a series of clock pulses in successive cycles which measure the length of a charge pulse to be stored in ancillary memory LT1 or LT2 in the form of a bit recurring over a predetermined number of cycles. The charge pulse read out from the ancillary memory during the corresponding time slot of a frame is integrated and rounded in a harmonics suppressor before being used to modulate the amplitude of a high-frequency carrier delivered to the respective subscriber line for stepping a pulse counter connected thereto. |
