| 摘要 |
PURPOSE:To perform simply the test for a transmission line and a counter station at one side station, by transmitting a signal which can be discriminated to the counter station during the preparatory time from the rise of a data transmitter to the permission for the start of transmission and then detecting the signal at the counter station to return it. CONSTITUTION:An MODEM tester 9 is connected to an A station 6, and the test switch of the station 6 is set at the remote loop back. Then the transmission request signal RS of the tester 9 is turned on to feed the carrier to the transmission line. Then the signal of a frequency (f) is superposed on the counter station 7 from an oscillator 10 in the station 6 by making use of the time during which a transmission enable signal CS is turned on. At the station 7, the signal of frequency (f) is detected in the time during which the carrier is detected and a receiving carrier detecting signal CD is turned on. At this moment, the station 7 switches the received data RD to return it to the transmitting data SD by means of a remote back signal detector 12. Receiving the data RD, the station 6 performs the collation and check of the data and carries out the test for the transmission line and the counter station. |
