Metering circuit for small PBXS - uses digital blocking signal to prevent double counting

摘要

The metering circuit for small p.b.x.s. has meters associated with each subscriber connection. The meters are controlled by a count pulse provided by the respective exchange contact and control circuit. A digital blocking potential is applied for a short time interval synchronized to the arrival of the local call charge pulse each time the exchange line is occupied and each time the count pulse is recorded. The blocking voltage prevents the initial state of the control circuit from changing. This applies to all other control circuits with the exception of that one which has prepared the appropriate gate associated with the meter. This avoids double counting of a pulse occurring during the call transfer interval.