# Error Modeling of Fiber Optic Gyroscope Universal Time Measurement
## 5 Conclusions  
This paper proposed a theoretical model based on the error correction of FOG. Through the analysis of the errors caused by various physical factors and mechanisms in the FOG measurement process, the observation equation model of FOG measurement is designed, and the corresponding error suppression methods are discussed. The error mechanism and its components are analyzed theoretically, with terrestrial tilt having the greatest impact on the measurement, followed by solid earth tide effect, and subsequently by polar motion, nutation, and precession. Finally, through the method of combining the geophysical model with the tiltmeter and VLBI observation data, a high-accuracy FOG-based solution for UT1 is achieved through the designed mapping function. The present study offers a more accurate model and method for high-precision UT1 field solution based on FOG. The experimental results demonstrate that the UT1 parameters solved by the FOG using the error correction model proposed in this paper are in general agreement with the trend of the standard value of EOP 14C04 provided by IERS, especially in the short term, with an error of less than 1 ms. A 14-day observation demonstrates that the giant FOG, with an accuracy of 2 \(\times\) 10\({}^{-10}\) rad/s at an integration time of 4000s, can achieve an RMSE less than 2.2 ms for the deviation between the FOG solution and EOP 14C04 under a room temperature environment without any vibration isolation and magnetic shielding devices. Compared with the traditional method, the method proposed in this paper shows error variations within a range of 3.57 ms, with a relative improvement of 56% in the UT1 solution accuracy. This advancement underscores the potential of the model to achieve more accurate UT1 resolution of FOG.  
Additionally, the current results in nonideal environments imply a more optimistic improvement expectation on performance. FOG can observe quantities not accessible by other space geodetic techniques, such as the retrograde diurnal polar motion and position of the instantaneous rotation axis of the earth, as well as other observational data. The unique capability for a high temporal resolution offers a new way to measure UT1 by monitoring the earth's rotation. With the continuous development of FOG technology, there remains significant potential for improvements in sensitivity and long-term stability. Future work will focus on enhancing the detection and correction of error terms, such as barometric  
\begin{table}
\begin{tabular}{c c c c c} \hline  & **Mean (ms)** & **STD (ms)** & **RMSE (ms)** & **MAE (ms)** \\ \hline
1 & \(-\)0.4533 & 0.8622 & 0.8373 & 0.8143 \\
2 & \(-\)0.1701 & 2.2931 & 2.2021 & 1.8706 \\
3 & \(-\)0.6450 & 0.5724 & 0.7965 & 0.6450 \\ \hline \end{tabular}
\end{table}
Table 1: Accuracy of the three measurement period FOG solution UT1 compared to IERS EOP 14C04.  
pressure variations in geophysical effects, electromagnetic and temperature interferences in the measurement environment, which will contribute actively to the UT1 solution.  
Conceptualization, Z.W.; Methodology, Z.W.; Validation, Y.Y. ([PERSON]), C.S. and J.Z.; Supervision, Y.Y. ([PERSON]) and Y.Z.; writing--original draft preparation, Z.W.; writing--review and editing, Y.Y ([PERSON]). All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Shaanxi Innovative Team for Science and Technology (No. 2023-CX-TD-01).  
The datasets presented in this article are not readily available because the data are part of an ongoing study. Requests to access the datasets should be directed to the author.  
The authors thank [PERSON], [PERSON], and [PERSON] of Peking University for their help in providing the giant fiber optic gyroscope and the experimental measurement site.  
The authors declare no conflicts of interest.