The parameter design for high-performance digital PGC demodulation technique

The optical fiber interferometer is widely used in signal measurement. The phase-generated carrier (PGC) demodulation technique is an effective signal processing method to demodulate sensing signals for an optical fiber interferometer for its wide dynamic range, high linearity, high resolution, passive sensor structure, etc. Because electronic components will bring more noise to the system, such as overload, improper resistance, etc. Its performance is limited by the analog demodulation techniques in the past. The digital demodulation technique has been used to increase the PGC demodulation performance in recent years. The arctangent approach which has good performance is one of the digital PGC demodulation technique. The non-ideal parameter of the arctangent approach has a significant impact on the extremely high-performance digital PGC demodulation system. For getting high-precision digital PGC demodulation performance, some parameters of arctangent approach are being designed in this paper, such as, the sample frequency, the sample accuracy, the precision of digital signal, the carrier frequency, the filter parameter which include the passband ripple, the stopband attenuation, and the passband cutoff frequency, etc. The conclusion of this paper is a good guide to choose the optimum parameter for the arctangent approach to gain a high-precision digital PGC demodulation system. In this paper, the influence of these parameters of the arctangent approach is analyzed through theoretical in detail, and their effect and selection scheme is validated through emulation based on MATLAB. The simulation result shows that the amplitude error is 0.045% and the phase resolution of system is 6.3 × 10^-7 rad/√Hz@1 kHz with the THD is below -90 dB.