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Fiber optical interferometers belong to highly sensitive equipments that are able to measure slight changes like distortion
of shape, temperature and electric field variation and etc. Their great advantage is that they are insensitive on ageing
component, from which they are composed of. It is in virtue of herewith, that there are evaluated no changes in optical
signal intensity but number interference fringes. To monitor the movement of persons, eventually to analyze the changes
in state of motion we developed method based on analysis the dynamic changes in interferometric pattern. We have used
Mach- Zehnder interferometer with conventional SM and PM fibers excited with the DFB laser at wavelength of 1550
nm. It was terminated with optical receiver containing InGaAs PIN photodiode. Its output was brought into measuring
card module that performs on FFT of the received interferometer signal. The signal rises with the composition of two
waves passing through single interferometer arm. The optical fiber SMF 28e or PM PANDA fiber in one arm is
referential; the second one is positioned on measuring slab at dimensions of 1×2m. A movement of persons over the slab
was monitored, signal processed with FFT and frequency spectra were evaluated. They rose owing to dynamic changes
of interferometric pattern. The results reflect that the individual subjects passing through slab embody characteristic
frequency spectra, which are individual for particular persons. The scope of measuring frequencies proceeded from zero
to 10 kHz. At experiments the stability of interferometric patterns was evaluated as from time aspects, so from the view
of repeated identical experiments. Two kinds of balls (tennis and ping-pong) were used to plot the repeatability
measurements and the gained spectra at repeated drops of balls were compared. Those stroked upon the same place and
from the same elevation and dispersion of the obtained frequency spectra was evaluated. These experiments were
performed on the series of 20 repeated drops from highs of 0,5 and 1m. The evaluation of experiments displayed that the
dispersion of measured values is lower than 4% and could be reduced by PM fibers usage.
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