| 摘要 |
PURPOSE:To simplify a testing system, by terminating a two-wire side of a subscriber's circuit by plural impedance characteristics so that its impedance can be switched, utilizing a reflection characteristic of a hybrid circuit of the subscriber's circuit, and measuring and testing a transmission characteristic. CONSTITUTION:On a subscriber's circuit SLC connected to a terminal equipment TEL, a calling circuit BSCH having various functions such as call current supply, supervision, two wire-four-wire-conversion, encoding, decoding, etc., separating switches COSWa, COSWb, and test leading-in switches TSTSWa, TSTSWb are povided. To this output and input highways HWO, HWI, a testing device TEST is connected through a time division switch TDSW. Also, to test connecting terminals Ta, Tb of the two-wire side of the circuit BSCH, a terminating circuit TERM having plural impedance characteristics is connected. In this state, the transmission characteristic is measured and tested easily by constituting so that the impedance of the circuit TERM can be changed over by a switch, and utilizing a reflection characteristic of the high ways HWO, HWI. |
