When measuring loss across a fiber link, where do measurements typically start and end?

Measurements of loss across a fiber link typically begin and end at specific points that correspond to the edges of the optical pulses. Initiating the measurement at the left side of the pulse at the beginning and concluding at the left side of the pulse at the far end ensures an accurate assessment of the signal's propagation and any attenuation that may have occurred throughout the fiber link.

Using the left side of the pulse, or the rising edge, establishes a clear reference point for when the signal is first introduced and where it is subsequently detected. This methodical approach allows for an accurate comparison of the launch and receive signals, helping to quantify the overall loss due to various factors such as absorption, scattering, and connector losses along the fiber.

This procedure underscores the importance of understanding pulse behavior in fiber optics, as well as the physics of light transmission through the medium, ensuring that installers can identify and troubleshoot any issues effectively. The other options do not follow this standard practice, making them less suitable for accurately measuring fiber link loss.