Research Of PGC Demodulation Method In Fiber-optic Interference Sensors System With DSP

Fiber-optic interference sensors become a research hotspot because of its many advantages such as high sensitivity, large dynamic range and structural versatility. Demodulation methods of fiber-optic interference sensors directly affect the dynamic range of sensing systems, detection accuracy and other important parameters. In many demodulation methods, Phase Generated Carrier (PGC) demodulation technique is widely used. Its structure is simple but the subsequent signal processing is very complex. If the technology is implemented digitally, we will give full play to the advantages of this technology.This paper has researched and designed the PGC demodulation systems of interference fiber-optic sensors, which is based on Digital signal processing (DSP) TMS320C6416development board, and finished these follow works:Firstly, we analysis the fundamental theory of the fiber-optic interference sensor, and make a detail research on the PGC demodulation technology with Bessel function, then simulate it with MATLAB, and verify the feasibility of this scheme.Secondly, many key technologies of the PGC demodulation system are researched and simulated, such as such as the choice of modulate parameter, the influence of contrast, the choice of sampling frequency and the bound of dynamic range.Thirdly, the development process of DSP TMS320C6416development board is mastered. Focus on CPU, pipeline, McBSP, EDMA, high-speed AD and other hardware and software resources and their performance characteristics. The data collection program of ping-pong buffer are designed which improves the system's real-time performance.Fourthly, with the integrated development environment CCS of DSP, we design the program block of PGC demodulate algorithm and the corresponding DSP development module. It mainly includes the signal production of first harmonic wave and second harmonic wave, low-pass filter, the differential cross-multiplication, differentiation algorithm, integral arithmetic and initial configuration of DSP. Debugging the program in the CSS, we get an ideal demodulation result.