摘要 |
A system to easily detect defective portions of a transmission line in a short time, wherein the optical signal which has been generated on the basis of the transmission pulse which is outputted in synchronization with the horizontal synchronized signal is transmitted via the transmission line, and the reflected-light component which has been reflected by the defective portion in the transmission line is received, and the gain of the reflected-light component is increased by one step for each predetermined number of a horizontal lines on the basis of the horizontal synchronized signal and then compared with the reference voltage, so that the binary data is obtained. The binary data is displayed, along with the axis of the abscissa which represents the distance of the transmission line corresponding to the time difference between the optical signal and the reflected-light component, and the axis of the ordinate which represents the signal level of the reflected-light component.
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