Patent GB-1141068-A (GB)
Title: Improvements in or relating to telecommunications exchange systems
IPC: H04M15/04
Filed: 1966-06-30
Abstract: 1,141,068. Metering in automatic exchanger. SIEMENS A.G. 30 June, 1966 [1 July, 1965], No. 29338/66. Heading H4K. In an exchange having a central control which keeps a current record of the state of the exchange, meter units each individual to one particular metering zone continuously count pulses fed to them at a pulse-rate appropriate to that zone, the charge made to a calling subscriber for a connection being calculated from the readings, at the connection's establishment and breakdown, of the meter unit of the zone of the called subscriber. The calling subscriber may be advised of the charge at the end of the connection or, if provided, the calling subscriber's charge indicator may-be operated each time a pulse is fed to the particular zone metering unit. As shown in the drawing a pulse generator T6 from each of outputs 1-X supplies pulses, at a frequency appropriate to a particular zone, to one of the subsidiary zone metering units TZ which for each nth pulse gives a charge unit pulse to the associated main zone charge metering unit GZ. From the dialled number of the wanted subscriber the zone code digit VZ is stored in the section of the store SP corresponding to the relay set RS allocated to the calling subscriber and which section also contains the calling and wanted subscribers' addresses. Upon the connection being made and again when broken, the zone code digit VZ is supplied to the selector D1 to effect read-out of the particular zone meter units TZ and GZ into store SP. Both readings are transmitted to store G-SP along with the two addresses to make out the charge slip. If n = 10 and TZ has a capacity of 10, the reading of TZ provides the decimal placings for the GZ reading resulting in one subtraction, otherwise the readings are subtracted separately; the final figure after subtraction may require rounding up if a fraction of a charge unit is involved. The connection is broken down then or after the subscriber has been advised of the charge. To operate the subscriber's charge indicator, one of bi-stable circuits BK1 to BKX is set each time a charge unit pulse is passed to zone charge meter unit GZ, which prompts the control ZST to perform a checking cycle. Accordingly the zone code digits in each storage location of SP are successively passed to decoder D2 to provide one input to the appropriate zone AND gate K; if the corresponding bi-stable circuit has been set a signal is sent through the AND gate so effecting transmission of a meter pulse to the subscriber whose store is currently being read. The period of the checking cycle is less than the smallest interval of any of the charge unit metering pulse trains. In an alternative arrangement the presence of the particular zone code digit in the storage locations is ascertained for each charge unit pulse arriving at each zone charge metering unit. However in both arrangements breakdown of the connection is delayed until the charge calculation has been made and it is determined if a further metering pulse is needed to be transmitted to the subscriber as a result of rounding-off the charge figure.