System for suppressing fading of distributed optical fiber acoustic sensor in real time

The invention provides a system for suppressing fading of a distributed optical fiber acoustic sensor in real time. The distributed optical fiber acoustic sensing system comprises a laser, a first coupler, a phase modulator, an arbitrary waveform generator, an acoustic optical modulator, an erbium-doped optical fiber amplifier, a band-pass filter, a second coupler, a circulator, a sensing optical fiber, a polarization diversity receiver, an analog-to-digital conversion module and an FPGA processor. The system executes a fading elimination algorithm and demodulates a phase signal in an FPGA processor, and comprises the steps of FIR filtering, Hilbert transform, complex conjugate multiplication, arc tangent, unwrapping and phase difference. An equal-intensity sideband is generated through phase modulation, and three paths of signals are combined by using a complex conjugate multiplication in an FPGA (Field Programmable Gate Array), so that interference fading is eliminated in real time. The polarization diversi