In OTDR terminology, what is 'dead zone' referred to?

In Optical Time-Domain Reflectometer (OTDR) terminology, the term 'dead zone' specifically refers to the unusable range after a reflective event. When the OTDR sends a pulse of light down a fiber optic cable, any reflections that occur from connectors, splices, or faults can create a dead zone where the instrument cannot accurately measure or detect further events. This happens because the instrument is still processing the reflected pulse from the previous event, leading to a gap where it cannot capture the next event. Therefore, this dead zone represents the area following a reflective event where accurate measurements of the fiber's condition cannot be obtained. It is crucial for technicians to understand this concept when interpreting OTDR results and analyzing the health of fiber optic installations.