JPS6138910B

PURPOSE:To increase the number of branch lines and the number of stations to be monitored, so that a fault position of the transmission line can be searched subdivisibly, by enabling to set the number of stations to be monitored, in the branch line of a wire TV transmission line, etc. as many as the detection resistance value can be decided. CONSTITUTION:Plural stations to be monitored 2', 3'-1-3'-3, 4'-1-4'-3 and 5'-1- 5'-3 are made to branch by the branching circuits having SV resistors (resistor which has been selected so as to have a prescribed value including the line resistance of each span) R1, and by connecting these branching circuits, a fault position in the branch line of a wire TV transmission line, etc. is searched by the monitoring station 1. The first diodes D1 are connected in parallel to the SV resistors R1 of the respective stations to be monitored 2', 3'-1-3'-3-5'-1-5'-3 of said branch line, the resistors Ra-Rc for branch discrimination are connected in series to the respective stations to be monitored 3'-1, 4'-1 and 5'-1 which are located just behind the branch point P, and to these resistros Ra-Rc are connected to the second diodes D2 so as to be opposite in polarity. And, a fault position of the transmission line is searched subdivisibly by increasing the number of branch lines and the number of stations to be monitored.