EXFO IQS-12002B Calibration System User Manual

Page 80

Calibration Methods

IQS-12002B

FTB-7000D and FTB-7000B-B OTDR Modules

Uncertainties

The uncertainties for distance calibration are as follows:

Reference fiber (as per the calibration certificate issued by the national
laboratory where the fiber was calibrated).

Environment temperatures.

Chromatic dispersion.

Wavelength differences: calibration wavelength for the reference fiber
versus OTDR wavelength, and OTDR wavelength uncertainties.

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.