An ameliorated phase-generated-carrier demodulation algorithm for sinusoidal phase-modulating fiber-optic interferometer

摘要

The phase-generated-carrier (PGC) algorithm is the most widely used signal demodulation method for fiber-optic interferometer sensors (FOIS), due to its distinct advantages of high resolution, wide dynamic range, good linearity and multi-channels demodulation capability. Even though significant progress has been made in PGC algorithm, the influence of phase modulation amplitude variation for PGC-differential-cross-multiplying approach (PGC-DCM) and PGC-Arctangent approach (PGC-Arc) still remains, especially on large-scale FOIS array. In this paper, a novel ameliorated digital PGC algorithm based on three-channel mixing signals has been present to mitigate this effect, which called PGC-differential-cross-dividing approach (PGC-DCD). The most distinguishing feature of this method is that it directly picks up the phase modulation amplitude from the interference signal by series of mathematical calculation and synchronically used in subsequent demodulation processing. So, the variation of phase modulation amplitude, induced by the internal or external disturbances, can be directly detected and synchronically updated in demodulation. The theoretical derivation and simulation experiment show that this approach is robust to the variation of phase modulation amplitude, and is a potential demodulation algorithm for FOIS, especially for large-scale FOIS array.