| 摘要 |
PURPOSE:To test a four-wire type telephone exchange easily, by connecting a two-wire type pseudo tester through a two-wire and four-wire converter. CONSTITUTION:The pseudo tester 1 is connected to the two-wire and four-wire converter 9 by two wires; and the device 9 and a main distributing board 2, and the main distributing board and a subscriber circuit 4 are connected by four wires respectively. A dial signal from the tester 1 is detected by a loop current detecting circuit 11 and reaches a dial pulse transmitting and receiving circuit 17 through a pulse counting circuit 13, binary-decimal converting circuit 14, electronic switch circuit 15, and microcomputer 16. Starting dial pulses are supplied to a four-wire subscriber circuit 4 through a control line 19 and a signal corresponding to a call is supplied to a four-wire subscriber circuit 4 through a channel 18 among the four wires. |
