| 摘要 |
PURPOSE:To perform the self-test of a terminal device simply and quickly by using a modulation and demodulation section in common use for two-wire and four-wire systems, and folding an output of a built-in network controller back to a reception line of the modulation and demodulation section. CONSTITUTION:A data signal is transmitted from a main control section (c) of a terminal device 1 to a modulation and demodulation section (b). The data signal transmitted to the section (b) passes through a built-in controller (a) via a transmission line (e) and is inputted to the section (b) from a reception line (f) of the section (b) via a subscriber telephone line connecting terminal (d) and transmitted to the section (c), where the transmitted data signal and the received data signal with folding are collated, to perform the self-diagnosis of the device 1 including the device (a). |
