| 摘要 |
PURPOSE:To attain ease of fault analysis by connecting a reception line and a transmission line to attain line folding and a line folding test of the own station to an opposite station in throwing a line folding test to the test mode. CONSTITUTION:When the line folding test switch 4a is set to the normal mode, a transmission data signal 5 is modulated into a frequency designated by a transmission/reception frequency selector 6 by a modulation circuit 7 and the result is transmitted to a transmission circuit 8. When the switch 4a is set to the test mode, the transmission/reception frequency selector 6 uses a test signal 12 so as to detect it and designates one of two kinds of modulation/demodulation center frequencies of the selector 6 to the modulation circuit 7 and a demodulation circuit 10 at the same time. Further, the modulation/demodulation center frequency is switched alternately in the timing when a data terminal ready signal 13 is turned off to test the two kinds of the modulation/demodulation center frequency. |
