RU1826134C - Optical cable attenuation measuring device - Google Patents

Abstract

Usage: technique for measuring the attenuation of a laid optical cable in fiber-optic transmission systems. The inventive device contains two optical pulse generators 1 and 16, a directional coupler 2, a photodetector 3, two selective amplifiers 4 and 5, three filters 6-8 modulation frequencies, two synchronous detectors 9 and 10, a comparison unit 11, an attenuator 13, two optical modulators 12 and 15, optical cable 14. 1-2-3-4- 6-9-11, 1-2-12-10, 3-5-7-9, 5-8-10- 11, 1-2-14-15-16. 1 ill.

Description

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The invention relates to the field of communication, and in particular to a technique for measuring the attenuation of a laid optical cable in fiber optic transmission systems.

An object of the invention is to expand the range of measurable attenuation.

The drawing shows a structural diagram of the proposed device.

The device contains a series-connected first optical pulse generator 1 and a directional coupler 2. photodetector 3, two selective amplifiers 4.5, three modulation frequency filters b, 7, 8, the first and second synchronous detectors 10, 9, the outputs of which are connected to the inputs of the unit Comparison 11, an attenuator 13 connected through a second optical modulator

12 to the control input of the first synchronous detector 10, the monitored optical cable 14, the first optical modulator 15 and the second optical pulse generator 16, connected in series

The operation of the device occurs in the following sequence.

The optical signal from the first optical pulse generator 1, modulated by the frequency fi, is fed to a directional coupler 2 and branched into two directions, fed to the input of the controlled optical cable 14 and to the input of the attenuator 13. Pass the attenuator

13 the signal is reflected from the second optical modulator 12 with a frequency of FL Pass controlled optical cable 14, the signal is reflected from the first optical modulator 15 with a frequency of F2, while in the intervals between reflections the optical signal from the second generator of optical pulses 16 having a modulation frequency i2 ( h Fa) passes through the first optical modulator 15 into the monitored optical cable 14 and, having passed it and directed the burner 2, enters the photodetector 3. Thus, the signals reflected from Odulov tori 12 and 15 at the frequency fi and the signal from the second optical pulse generator 16 at frequency fs. Signals at frequencies fi and h from the output

photodetector 3 are amplified by selective amplifiers 4 and 5. The amplified signals at frequency fi are fed to filters 7 and 8 of the modulation frequencies of optical modulators

12 and 15. The selected signals at frequencies FI and F2 by filters 7 and 8 are fed to the information inputs of synchronous detectors 9 and 10. Signals from the filter are fed to the control inputs of synchronous detectors 9,10

6 and the optical modulator 12. The signals from the outputs of the synchronous detectors 9 and 10 are fed to a comparison unit 11, where they are compared by attenuation by an attenuator 13.

The proposed device allows to increase the range of measured attenuation without compromising accuracy.

Claims (1)

The claims An optical cable attenuation measuring device, comprising a first optical pulse generator, a directional coupler and a photodetector, two selective amplifiers, two synchronous detectors, the output of which is connected to the corresponding inputs of the comparison unit, characterized in that, in order to expand the limit of the measured attenuation and To increase accuracy, a second optical pulse generator and a first optical modulator are introduced in series, the output of which is through a controlled an optical cable is connected to the corresponding input of the directional coupler, an attenuator connected in series, the input of which is connected to the corresponding output of the directional coupler, and a second optical modulator, the output of which is connected to the control input of the first synchronous detector, three modulation frequency filters, the photodetector output through selective amplifiers are connected respectively to the inputs of the corresponding modulation frequency filter, the outputs of each of which are connected respectively to the control input of the second synchronous detector and the information inputs of the first and second synchronous detector.