| 摘要 |
PURPOSE:To measure the bit error rate, by transmitting a random pattern signal from a station and comparing it with a signal returned from a digital telephone set. CONSTITUTION:A digital signal produced at a random pattern generating circuit 17 is applied to a callout signal pattern eliminaing circuit 18, and after the same digital signal as the callout signal pattern is changed into other patterns, it is transmitted to a subscriber circuit via the link. A signal transmitted from the subscriber circuit to the subscriber line is folded at a digital telephone set and inputted to one of a pattern comparison circuit via the subscriber circuit and the link. The output of the circuit 18 is connected to another input of the circuit 19, where both digital signals are compared to calculate the bit error rate. |
