Using the Rao-Cramer inequality, the lower bound of the dispersion of the effective estimate of the modulation index of the homodyne laser Doppler vibrometer (LDV) signal was calculated. Methods for processing the homodyne LDV signal for various types of optical circuits are proposed. Numerical simulation and comparison of the signal processing algorithm with a modulation index estimate on the spectrum width for a single-channel homodyne LDW scheme and a processing algorithm for a circuit with an optical quadrature channel are performed.