The present invention discloses a carrier
demodulation method based on eliminating the influence of modulation depth by third
harmonics. The method uses a modulation depth
elimination module to eliminate the influence of
light intensity disturbance and modulation depth drift by performing operations such as subtraction, self-differentiation multiplication, and division on the sine and cosine components after
frequency mixing and filtering, followed by single, double, and
triple frequency multiplication. After the
phase resolution module performs power reduction operations and sign judgment, the phase to be resolved can be accurately calculated, and the modulation depth value of the current
system can be accurately calculated by the modulation depth resolution module. The present invention can eliminate the influence of the modulation depth of the external carrier on the demodulated
signal, and can also eliminate the influence of
light intensity disturbance on the demodulated
signal, so that the
demodulation result has a high
signal-to-
noise ratio and low
harmonic distortion, thereby improving the accuracy of signal amplitude detection and the stability of the
demodulation system. It can be widely used in high-precision
optical fiber measurement and sensing systems.