| 摘要 |
PURPOSE:To detect even a slight failure by transmitting a DC code having a prescribed period to a transmission line including a repeater and changing a DC operating point as an identification level of the repeater to generate a transmission error, and detecting a marging of error generation of the entire transmission line. CONSTITUTION:In Figs. A, B and C, a code ''001111'' is transmitted repetitively. That is, the ''1'' component is much in any case, resulting that the DC operating point of the identification level of each repeater 3-i is increased. In increasing the ''1'' component in the order of A, B, C..., the DC operating point of the identification level of the repeater is increased and the result of identification starts to produce an error finally. The margin of error generation is detected by allowing a supervising device 5-i to detect it. Similarly, in increasing the ''0'' component in the order of D, E, F, the DC operating point of the identification level of the repeater falls down and the result of identification starts to produce an error finally without fail. |
