Study And Analysis On The Performance Of High-precision Fiber-optic Time Transfer System

With the development of science and technology,human beings are increasingly demanding on the performance of time synchronization.High precision time synchronization plays a crucial role especially in deep space exploration,national defence-related science and technology and other important areas.Compared with the traditional cable,optical fiber has the advantages of low loss,high bandwidth,strong anti-electromagnetic interference performance and also has better stability than the free space channel.Long distance and high precision time and frequency transfer through optical fiber link has attracted wide attention.In this paper,the influence of different factors on the performance of fiber-optic time transfer is analyzed theoretically by building the mathematical model.The main work of this paper includes following aspects:(1)Model of wavelength variations including random jitter and drift is established based on the statistical analysis of the measured wavelength fluctuation data of SFP(Small Form-factor Pluggable)optical module.(2)Delay fluctuations model of long distance and segmented optical fiber time transfer link is established.The relationship between the stability of fiber-optic time transfer and the variations of laser wavelength and the temperature of optical fiber link is derived by using a link segmentation processing method.The effects of jitter and drift of wavelength,depth of buried optical fiber link and work season of time transfer on the stability of fiber-optic time transfer adopting bidirectional time division multiplexing and wavelength division multiplexing respectively are analyzed on a 3000 km optical fiber link emulated by the actual temperature data.(3)The relationship between the double rayleigh scattering(DRB)noise and the optical power in the receiver is derived,and the reliability of the derivation process is verified by simulation.(4)Noise analysis model is established based on the link of BTDM optical fiber time transfer,considering effects on the performance of optical fiber time transfer of the ASE noise of amplifier,double rayleigh backscattering noise,intensity noise and phase noise of laser,shot noise and thermal noise of detector.The effects of different factors on the performance of optical fiber time transfer based on BTDM and WDM are analyzed and compared from three angles of the transmitter,the optical fiber link and the receiver.