Reaseach On The Universal Time Solving Method Based On The Large-scale Fiber Optic Gyroscope

Universal Time(UT1)is one of the Earth orientation parameters,it is one of the necessary parameters to realize the mutual conversion between the celestial coordinate system and the terrestrial coordinate system,it plays an important role in deep-space exploration,aerospace and other research fields.UT1 is time-varying and difficult to predict accurately for a long time,it needs to be measured regularly.At present,the independent observation and calculation of UT1 parameters in China is still not perfect,the UT1 parameter services required in various domestic research areas are obtained by international cooperation currently.Because of its importance,it is necessary to establish an independent UT1 observation and calculation system.Large-scale fiber optic gyroscope(FOG)are sensitive to measuring the earth rotation variation,and it has the potential to become a new method of UT1 measurement technology.National Time Service Center(NTSC)has initially established a large-scale FOG observation platform,and begins to observe and research the Earth rotation motion using large-scale FOG.Among them,the calculation of UT1 parameters and the error correction methods in the solving process are one of the key tasks of this research.Aiming at the problem of the low time resolution of the current UT1 parameters,and combined with the characteristics of large-scale FOG that can measure the earth rotation in real time,the thesis deeply analyzes various physical factors affecting the measurement of FOG and the physical mechanisms affecting the measurement results,based on this,the thesis proposes a corresponding error correction model,and establishes a mapping function of real-time measurement and calculation UT1 parameters based on large-scale FOG.At the same time,the thesis designs the basic structure of the Earth rotation clock based on the large-scale FOG,and proposes a method for the calibration of the Earth rotation clock.And through the analysis of the raw data,the feasibility of a large-scale FOG as a new UT1 measurement technology has been demonstrated.The near real-time solution of the UT1 parameters using the raw measurement data from the large-scale FOG is preliminarily realized,the method initially achieves the goal of increasing the time resolution of the UT1 parameter based on the measurement of the large FOG.The main research work and innovations of this thesis are as follows:1.Based on the basic measurement principle of FOG,and combined with the FOG observation platform,the observation equation of measuring Earth rotation velocity accurately by FOG is established by using the coordinate transformation relationship between different coordinates.According to the observation equation,the paper proposed the corresponding data processing flow.2.The tilt of the FOG observation platform from the earth tide and local geophysical effect causes the problem of producing orientation error in the raw measurement data of the FOG.Combined with the source and characteristics of the orientation error,it analyzed the influence mechanism of different error sources on the measurement of the FOG,and proposed correction method for orientation error.Finally,it separates the orientation error and Earth rotation data from the original measurement data.3.For the problem that cannot get the earth rotation velocity inforations directly from the FOG raw data because of the FOG instrument noise,it first analyzes the noise characteristics of the FOG using measured data.According to the noise characteristics,the corresponding noise-correction method is proposed: the interval 5 min moving average method can eliminate the interference caused by noise to the greatest extent.After denoising,the data reflects the accuracy of the Earth rotation velocity to-103?10-1rad ×s.4.Aiming at how to use the FOG measurement data to solve the UT1 parameter,the paper first proposed the pointing relations between the Earth rotation velocity based on FOG measurement and the UT1 parameter.Numerical integration of the relative variation of the Earth instantaneous velocity can realize the conversation of UT1 parameter.It verifies the feasibility of the UT1 solution method by using the measurement data of FOG,the time resolution for the UT1 parameter solution has reached to 5 mins finaly.It is first time to realize the measurement and calculation of UT1 parameters by using the FOG in our country.5.The UT1 solution method based on large FOG can be used to the Earth rotation clock system,it has been researched and designed the basic structure of the Earth rotation clock system based on large-scale FOG.At the same time,for the problem that the large-scale FOG is not convenient to use rotary table to calibrat the initial scale factor,using the stability of the Earth rotation velocity can realize the calibration of the large-scale FOG.In addition,the article also proposes a calibration method for the Earth rotation clock based on large-scale FOG.Comparing the solved UT1 parameters from the FOG with the UT1 parameters form the IERS can calibrate the Earth rotation clock periodically.The calibration method is used to solve the problem that the UT1 parameter from the long-time operation Earth rotation clock deviates gradually from the true value because of the drift phenomenon of the FOG.