MEASUREMENT OF LINEARITY IN OPTICAL TIME-DOMAIN REFLECTOMETERS

摘要

This document begins by introducing the concept of nonlinearity and its importance in making accuratemeasurements using optical time-domain reflectometers (OTDRs). The document reviews varioustechniques for measuring the nonlinearity of OTDRs and introduces a new technique that makesmeasurement of this historically difficult parameter far easier to accomplish. The new techniqueinvolves the acquisition of two waveforms, one with a known amount of excess front-panel loss over theother. The algorithm subtracts these two waveforms and compares the difference with the known amountof excess loss. This comparison leads naturally to a graphical representation of the OTDR’s nonlinearityas a function of vertical-scale reading.