Which device is the fiber optic equivalent of a copper Time Domain Reflectometer, used to locate breaks and measure loss along fiber links?

Which device is the fiber optic equivalent of a copper Time Domain Reflectometer, used to locate breaks and measure loss along fiber links?

• A. TDR
• B. OTDR
• C. Light Meter
• D. Cable Tester

Answer: (B)

The concept being tested is locating faults and measuring loss along a fiber link using time-domain reflectometry with optical signals. The fiber-optic counterpart to the copper TDR is the Optical Time Domain Reflectometer (OTDR). It works by launching a very short pulse of light into the fiber and monitoring the light that returns over time. Since light travels at a known speed in the fiber, the time axis maps to distance, letting you pinpoint where reflections or higher loss occur along the cable. The resulting trace shows events like connectors, splices, bends, or breaks and the amount of loss between them, which is exactly what you need to locate breaks and measure attenuation along the link. A light meter merely measures the optical power at a point, not where along the fiber the loss is occurring. A cable tester can check basic connectivity but typically doesn’t provide a detailed loss profile along the length. A copper Time Domain Reflectometer uses electrical signals and impedance changes in copper cables, which isn’t suitable for characterizing fiber optics.

The concept being tested is locating faults and measuring loss along a fiber link using time-domain reflectometry with optical signals. The fiber-optic counterpart to the copper TDR is the Optical Time Domain Reflectometer (OTDR). It works by launching a very short pulse of light into the fiber and monitoring the light that returns over time. Since light travels at a known speed in the fiber, the time axis maps to distance, letting you pinpoint where reflections or higher loss occur along the cable. The resulting trace shows events like connectors, splices, bends, or breaks and the amount of loss between them, which is exactly what you need to locate breaks and measure attenuation along the link.

A light meter merely measures the optical power at a point, not where along the fiber the loss is occurring. A cable tester can check basic connectivity but typically doesn’t provide a detailed loss profile along the length. A copper Time Domain Reflectometer uses electrical signals and impedance changes in copper cables, which isn’t suitable for characterizing fiber optics.