Enhancing scale factor stability of IFOGs through an optimized proper frequency measurement method: The even frequency doubled sine wave modulation

Even frequency doubled sine wave modulation is an existing method for measuring the proper frequency of closed-loop interferometric fiber optic gyroscopes (IFOGs). In this paper, we first provide a comprehensive explanation of the underlying principle of this method. Secondly, we refine the existing approach and expand its applicability from IFOGs using square wave modulation to those using four-state modulation. On this foundation, we present both theoretical and experimental evidence demonstrating that this method can enhance the stability of the IFOG's scale factor. During a linear heating process from −40 °C to 60 °C, the angle random walk (ARW) exhibited a slight decrease of 1.4%, while the stability of the FOG's scale factor significantly improved by a factor of 6.7 in our evaluation system. Moreover, for the first time, we reveal the interaction between the added sine wave and the original rotation rate demodulation system. This interaction is analyzed theoretically, and the conclusions drawn from this analysis are supported by experimental validation.