| 摘要 |
<p>A transmission signal output from one's own electronic device can be easily distinguished. A transmission part (7) outputs the transmission signal toward a transmission path (1) connected with terminal resistors (r1, r2). Switching parts (Q1, Q2) are connected between a constant voltage power source and the transmission path (1) for turning ON/OFF a signal supplied from the constant voltage power source by the transmission signal from the transmission part (7) and outputs the signal to the transmission path (1). A reception part (9) receives the transmission signal from the transmission path (1). A detection part (13) is connected between the constant voltage power source and the switching parts (Q1, Q2) for detecting the transmission signal flowing through the switching parts (Q1, Q2) from the transmission part (7). A selection part (15) selects the reception part (9) for outputting a received signal when the detection part (13) does not detect the transmission signal from the transmission part (7).</p> |
