What does the Cursor Value on AQ7275 Optical Time Domain Reflectometer Measure?

The cursor value displays the level (dB) of the signal that is above the noise floor of the connected optical port. The noise floor is the dynamic range. This lets you know if you are approaching the maximum distance that you can test with the OTDR. As the cursor value approaches zero, the OTDR is nearing its maximum measurable distance, due to the condition of the fiber optic cable.  

Please download the attached PDF for more information regarding the cursor value.