What does an OTDR measure in fiber optics?

An OTDR, or Optical Time Domain Reflectometer, is specifically designed to analyze fiber optic cables. The fundamental capability of an OTDR is to measure the time it takes for a light pulse to travel through the fiber, as well as any reflections that occur due to imperfections in the fiber or at connection points. This allows it to determine fiber length and identify points of trouble like breaks or defects along a cable.

While "data points" might suggest that the OTDR measures several aspects of fiber performance, it does not precisely capture the essence of what an OTDR does. The primary focus is on distance and reflection points rather than merely collecting arbitrary data points without context.

The other options pertain to different areas of technology. Electrical resistance is a measurement relevant to electrical systems, while signal processing relates more to how signals are managed and manipulated in various technologies. Fiber length, while a relevant outcome of the OTDR's performance, is not commonly classified as just "data points."

In summary, while data points may appear to encompass a range of measurements, it's more precise to say that the OTDR directly measures fiber length and detects faults by analyzing return signals, making it a specialized device for fiber optic evaluation.