EXFO OTDR 2 - Manual (Page 53)

OTDR 45
4 Testing Fibers
Several tools are available to perform complete OTDR tests; you can also
control all test parameters.
By default, all available test wavelengths are selected.
You can either set the acquisition parameters yourself or let the application
determine the most appropriate values.
In the latter case, the application will automatically evaluate the best
settings according to the fiber link currently connected to the unit.
The pulse width will be determined using a factory-defined signal-to-noise
ratio (SNR) requirement specified where the End-of-Fiber (EoF) event has
been detected.
The EoF event detection algorithm uses the end-of-fiber threshold defined
in the Test Configuration window (for more information, see Setting the
Analysis Detection Thresholds on page 30). If you are not sure about which
value to choose, revert to the factory default value for this parameter.
Although the application sets the acquisition parameters, you can modify
these values as needed, even while the acquisition is in progress. The
OTDR simply restarts the averaging each time a modification is made.
Note: You can interrupt the acquisition at any time. The application will display
the information acquired to that point.