FIELD: physics.
SUBSTANCE: in compliance with proposed method, train of sounding optical pulses with duration exceeding pulse propagation time on beat length are sent into optical fiber transmission line closest end. Reverse Rayleigh process signal coming to closest end from optical fiber is sent to optical radiation polarisation analyser with its output receiving power of one-polarisation optical radiation. Reverse Rayleigh process characteristic is measured. Variable component of said characteristic is extracted to be divided into elementary sections to estimate mean beat length on every elementary section (LB)z as half the period of variable component variation along fiber. Proposed method differs from known designs in that duration of sounding pulse T0 is varied linearly with preset spacing subject to the following conditions: vg · (T0) >> LB and (T0 max - T0 min) << (T0), wheree LB is beat length, vg is group speed of optical pulse propagation in fiber, (T0) is mean duration of sounding pulse, and T0 max and T0 min are duration maximum and minimum values, respectively. Reverse Rayleigh process characteristic is repeatedly measured and memorised for every duration of sounding pulse. For every fixed coordinate z along fiber, beat length LBT is defined as doubled period of variation of variable characteristic depending upon sounding pulse duration, esteems errors are defined as difference (LB)2-LBT, beat length is defined equal to esteems of LBT calculation of z at which error esteems do not exceed preset threshold.
EFFECT: reduced error of measuring beat length.
1 dwg
