| abstract |
(57) [Summary] [Problem] To accurately detect occurrence of a failure in a trunk of a bidirectional CATV system. SOLUTION: CAT is performed between a center station 10 and a subscriber station 20. Bidirectional C for bidirectional signal transmission via V transmission path 30 In the monitoring system of the ATV system, a monitoring cable modem 32 provided with an individual IP address is provided at an arbitrary position on the CATV transmission line 30 other than the subscriber's house, and each monitoring cable modem 32 is designated from the center station 10. Then, a communication diagnosis test is performed, and a failure location is determined on the basis of the test result, whereby a failure occurrence location in the CATV transmission line 30 is detected. |