FIELD: monitoring of characteristics of fiber-optical cable used in communication systems for measurement of distributed temperature and stress along optical fibers. SUBSTANCE: the optical power of a low-coherent laser emitting a continuous-wave light at a pumping frequency is applied via a controlled optical shutter to the first input of the adder and to the input of the fiber-optical ring used for regeneration of the Stocks return wave due to the stimulated Brillouin scattering (SBS) in the element of the active medium, in which the Stocks offset frequency equals the Stoks offset frequency in the fiber under investigation. The total power of the impulse pumping wave at optical frequency WH and continuous Stoks wave at optical frequency WH-ΩCO from the adder output via the passage arm of the adder output via the passage arm of the measuring directional coupler is fed to the input of the fiber under investigation. The resultant echo signal from all the enabling domains (elements) is fed via the directional arm of the measuring directional coupler to the input of the photodetector, in which it is detected, amplified and, after transformation, is fed to the processor device for analysis. As a result of measurements, the variation of signal attenuation in the length of the tested fiber is determined, which occurs due to the presence of heterogeneities in the structure of the latter, the type and location of the mentioned heterogeneities are determined. EFFECT: enhanced accuracy and expanded functional abilities due to the use both of the Brillouin and Raman scatterings. 4 cl, 3 dwg
