EXFO IQS-12002B Calibration System - Manual (Page 80)

Calibration Methods
76 IQS-12002B
FTB-7000D and FTB-7000B-B OTDR Modules
Uncertainties
The uncertainties for distance calibration are as follows:
³
Reference fiber (as per the calibration certificate issued by the national
laboratory where the fiber was calibrated).
³
Environment temperatures.
³
Chromatic dispersion.
³
Wavelength differences: calibration wavelength for the reference fiber
versus OTDR wavelength, and OTDR wavelength uncertainties.
³
OTDR resolution.
Traceability
Distance calibration is performed by comparing the length of a reference
fiber (traceable to a national metrology institute) as measured by the OTDR
under test with the reference fiber length given by the specification.
Reference fibers are calibrated at NPL (National Physical Laboratory in the
UK) or METAS (Swiss Federal Office for Metrology).
EXFO traceability of OTDRs
Working
standard
Reference fiber
DUT
OTDR
Reference fiber calibration is traceable to the national metrology of
Switzerland, named METAS or Swiss Federal Office for Metrology.