Optical time domain reflectometry system - uses complementary pseudo-random pulse sequence for compensating reflections

摘要

The reflectrometry system uses a pseudo-random pulse sequence for modulation of laser light fed to an optical fibre (13), with the detected back scattered signal correlated with the pseudo-random pulse sequence. The interference reflections are compensated using a complementary pseudo-random pulse sequence (12a) which is delayed for a given interval before superimposing it on the back scattered signal, with suppressed reflection converted into a DC component. Pref. an auxiliary laser (16) is modulated by the complementary pseudo-random pulse sequence, its light fed to one arm of an optical coupler for optical compensation of the back scattered signal. ADVANTAGE - Reduced dynamic losses.