METHOD AND DEVICE FOR CONTINUOUSLY MONITORING AN OPTICAL TRANSMISSION PATH

The main steps of the invention comprise feeding a sample signal (SOTDR) into the transmission line or path (2) using a multiplexer (8) during a current signal transmission and measuring the intensity of said sample signal (SOTDR), which is also coupled out via the multiplexer (80 and is reflected partially at faulty or error points. Part of the signal to be transmitted (Sin) can also be deviated by means of a coupling device (4) and the intensity of this proportion of the signal (Sup) can be compared with a threshold value. By evaluating the intensities that are measured, it is possible to detect and localize defects in the transmission path (2) or judge the quality of the transmission path (2 without interrupting the transmission.