SU1647248A1 - Method for optical reflectometer test calibration and device thereof - Google Patents

Abstract

The invention relates to measurements in fiber-optic communication systems and can be used to calibrate optical reflectometers. The purpose of the invention is to improve the accuracy of calibration, expanding the dynamic range of calibration and simplify calibration. The method consists in converting a sequence of driving pulses into a sequence of electrical pulses, generating electrical echo pulses delayed with respect to driving pulses for an adjustable time interval, forming reference time slots by converting the resulting sequence of electrical driving pulses and echo pulses into a sequence optical pulses compare the obtained reference time intervals with the time scale of reflectometer and the results of the comparison is judged on the error reflectometer, 2 SP f-ly, 2 ill.

Description

The invention relates to the field of measurements in fiber-optic communication systems and can be used to calibrate optical reflectometers used to measure the distance to a fault in optical fibers (0V) and optical cables (OC). as well as an optical pulse generator.

The purpose of the invention is to improve the accuracy of verification, expanding the dynamic range of verification and simplify the verification operation.

FIG. 1 shows a functional diagram of the device; 2 shows the influence of the amplitude and duration of the pulses on the error in determining the time interval.

between them both by the method of maximum amplitudes and by the method of the leading edges of pulses.

The device contains optically coupled laser radiation source 1 and phototransducer 2, pump generator 3, the output of which is connected to the input of laser radiation source 1, connected in series adjustable delay line 4, waiting for multivibrator 5, amplifier 6, controlled divider 7 and mixer 8, first 9 and 10 second integrators, the first 11 and second 12 amplitude detectors, the output of the photovoltaic converter 2 is connected to the second input of the adjustable delay line 4, the first inputs of the first integrator 9, the mixer 8 and the first amplitude about

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detector 11, the output of which is connected to the output of the second amplitude detector 12, and the input to the second input of the controlled divider 7, the input of the second amplitude detector 12 is connected to the output of the controlled divider 7 and to the second input of the first integrator 9, the output of the mixer 8 - with the input of the pump 3 generator, controlled input of the waiting multivibrator 5 - with the output of the first integrator 9.

The device that implements the method works as follows.

An optical pulse, taken from a calibrated reflectometer, specifying the initial time instant t0 and having a duration T0 and amplitude V0, is fed to a photoreceiver 4, in which it is converted into an electrical pulse with the same time parameters T0 and T0 and with some amplitude Vi . Passing through the delay line, this initial impulse is delayed by the precisely set time At ti -10 and simultaneously broadened by -T0 and reduced in amplitude, i.e. V 2 VL The distortion of the pulse shape leads to an error in creating their position on the time axis. To reduce this error, it is necessary to equalize the duration and amplitude of the pulses that specify the time interval. For this, a pulse received after the delay line is applied to the standby multivibrator 5. At the output of which, using the control signal AV produced by the integrator 9, a pulse with a reduced duration is formed, eventually equal to ω then this pulse is amplified by amplifier 6 to a certain amplitude value Va , with V3 being made considerably larger than V.

To equalize the amplitude Uz of the delayed pulse to the amplitude Vi of the initial pulse, they are detected in the amplitude detectors 11 and 12, based on a comparison of their amplitudes, the integrator 10 generates a control signal for the division factor of the controlled divider 7, as a result of which the output of the controlled divider 7 is formed impulse with parameters ti; go; VL When two mixer pulses are applied to the inputs of the mixer, 8: delayed with parameters ti; TO,; Vi initial with parameters t0; TO,; Vi at its output forms

with a pair of pulses with a time shift between them equal to At. The pair of pulses thus formed is fed to the pump generator 8 and then to the laser radiation source 1, where it is converted into a pair of optics

5 0 5 0

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five

pulses with the same time parameters At-, At0 and some amplitude V4, the same for two pulses. Then, through the optical coupler and the input-output optical connector, a pair of optical pulses defining the time interval A t required for the calibration of the optical reflectometer is fed to the turn adjustable reflectometer.

The verification operation consists in precisely combining the moments of the to and ti optical pulses with the starting and ending points of the reflectometer's scale being calibrated using a precision adjustable delay line, the digitized value of which determines the accuracy of coincidence AL with the value of the limits of the measuring range of the optical reflectometer.

Claims (2)

1. The method of verification of optical reflectometers, which consists in forming reference time intervals between the reference optical pulses of the calibrated reflectometer and echo pulses, compare the obtained reference time intervals with the time scale of the calibrated reflectometer and compare the results of the error of the reflectometer differing from that, in order to expand the dynamic range of the calibration, increase the accuracy and simplify the calibration, convert the sequence of the specifying optical pulses into a sequence of electrical pulses that generate electrical echo pulses delayed with respect to the master electrical pulses for an adjustable time interval, the reference time intervals are formed by converting the resulting sequence of electrical oscillators and echo pulses into a sequence of optical pulses, the generated reference time intervals are fed to the input of the test optical reflectometer. 2. A device for checking optical reflectometers containing an optically coupled laser radiation source and a phototransducer, a pump generator, the output of which is connected to the input of a laser radiation source, characterized in that it is equipped with series-connected adjustable delay lines waiting to increase the accuracy of the calibration a multivibrator, an amplifier controlled by a divider and a mixer, the first and second integrators, the first and second amplitude detectors, the output of the photoconverter is connected to orymi adjustable delay line inputs, the first inputs of the first integrator and the first amplitude detector, whose output is connected to a first input of the second integrator, the second input of which is connected to the output of the second amplitude detector, and the output is connected to the second input of the controlled divider, the input of the second amplitude detector is connected to the output of the controlled divider and to the second input of the first integrator, the output of the mixer is connected to the input of the pump generator, the controlled input of the waiting multivibrator is connected to the output the first integrator. R "Rm / I Device loberki onmuvecxux ref ex / scrap / lobj FIG. one / Y JlWM At Y nl P 4U Jl q g FIG. g 7 i