OTDRs display trace results by plotting reflected and backscattered light versus distance along the fiber, characterizing any reflective and non-reflective events in a fiber link. These reflections, known as Fresnel reflections, are meticulously measured by the OTDR to pinpoint the location of these events within the fiber link. Due to the inherent structure of the fiber and microscopic imperfections within the glass, a small portion of the light pulse scatters in various. An optical time-domain reflectometer (OTDR) is an optoelectronic instrument used to characterize an optical fiber. The OTDR is also commonly used to create a "picture" of fiber optic cable when it is newly installed. However, its value lies not only in taking measurements but also in correctly interpreting the records (traces) it generates.