Optical fiber length measuring device and method based on eigenfrequency of optical fiber ring

The invention discloses an optical fiber length measuring device and method based on the eigenfrequency of an optical fiber ring, and belongs to the technical field of optical fiber length measurement. And then a corresponding sine wave modulation signal is set based on the phase difference of two opposite beams of optical signals of the to-be-measured optical fiber ring, the second harmonic voltage amplitude in the signal is calculated through the digital signal processing module, the value of the modulation frequency is determined, and the exact length of the to-be-measured optical fiber ring is calculated. According to the invention, based on the Sagnac effect, sine wave modulation signals are adopted, solving is carried out in a symmetric point finding mode, and compared with an existing square wave modulation measurement method, the method is not influenced by modulation dead zones, has low requirements on data acquisition equipment, is low in measurement cost, is high in measurement precision, and is re