Phase generator carrier (PGC) digital demodulation method for interferometric fiber optic sensor and device thereof

Abstract

The invention provides a phase generator carrier (PGC) digital demodulation method for an interferometric fiber optic sensor and a device thereof. The PGC digital demodulation method for the interferometric fiber optic sensor comprises the following steps: outputting interference light intensity signals including sensing signals phi(t), and carrier signals by adopting the PGC technique; performing discrete sampling on the interference light intensity signals in the whole observation time T to obtain time domain sequence signals of the interference light intensity signals; by taking a carrier fundamental frequency cycle Tc as a unit, dividing the T into a plurality of time slots, and performing discrete Fourier transformation (DFT) on the time domain sequence signals in all the slots Tc to obtain the frequency spectrums of the time domain sequence signals; performing inverse discrete Fourier transformation (IDFT) on the frequency spectrums to reconstruct corresponding time domain signals; and according to the relation between the harmonic amplitudes of the reconstructed signals and the harmonic amplitudes of continuous signals, calculating the in-phase components cosphi(t) and the quadrature components sinphi(t) of the sensing signals phi(t) in all carrier cycles Tc, and performing the calculation slot by slot until the cosphi(t), sinphi(t) and the sensing signals phi(t) in the whole observation time T are obtained, and signal PGC demodulation is realized by the digital technology. A mixing system is not adopted, a local oscillation signal is not needed, and the problems, such as carrier signal synchronization and the like do not exist, and the overall performance is better.

Description

technical field [0001] The invention relates to the technology of the interference optical fiber sensor, in particular to the PGC digital demodulation technology of the interference optical fiber sensor. Background technique [0002] Generally speaking, the internal structure of the interferometric fiber optic sensor is a two-beam interferometer, and the total intensity signal of the interference light output by it is I T (t), I T (t) satisfy the following cosine function relationship: Among them, A and B represent the DC background parameters and contrast parameters of the interference light, respectively, is the phase difference between the reference arm and the signal arm of the interferometer, Including the initial phase difference of the two arms The phase shift caused by the sensing signal and phase shifts introduced by various noise which is Due to external conditions such as ambient temperature, pressure, and vibration, as well as factors such as the ph...

AI Technical Summary

Problems solved by technology

Since the attached figure 2 The working principle of the traditional PGC is shown. The system uses the combination of DSP and FPGA to complete the demodulation process. The system is really complicated.

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