A break occurs in a fiber with a loss of 3 dB/km. The output power from an OTDR set used to locate the break is 250 mW and the detected echo power is 1 μW. Approximately 10 dB of loss are encountered in coupling the OTDR signal into the fiber and the returned signal encounters 6 dB of loss at the optical splitter (see Fig. 3.4 on page 44). The reflectivity of a perpendicular break in the fiber is approximately 4%; the average reflectivity of a non perpendicular break is about 0.5%. Using the latter value of reflectivity, calculate the distance to the break in the fiber.

Fig: 1