The Research On Stable Phase Transmission System Based On Fiber Dispersion Delay

Highly stable frequency signals are used in a variety of electronic fields.There are still many fields that require two or more frequency signals to be synchronized,which involves long-distance transmission of frequency standard signals.It is difficult to meet the demand for high-stability signals by using traditional methods to transmit frequency standard signals.With the emergence and rise of microwave photonics,more and more researchers are considering and experimenting with optical fibers for transmission of frequency standard signal.The optical fiber is small in size,light in weight,low in loss,low in price,anti-electromagnetic interference and communication security.It is an ideal medium for transmitting signals.However,when the frequency-standard signal modulated onto the optical carrier is transmitted in the optical fiber,it will be subjected to an irregular change of the transmission delay that is phase jitter,due to interference from an external environment such as temperature,strain,and vibration.The existence of phase jitter affects the frequency stability of the frequency signal transmitted to the remote station,so compensation techniques are needed to compensate for the phase jitter caused by the environmental factors on the frequency-standard signal.The signal phase obtained by the remote station can remain synchronized with input signal of the central station.The paper introduces the research background of fiber-optic steady-phase transmission and the research status at home and abroad,analyzes the influence of external environment changes on the phase of the transmitted signal,discusses the basic principle of dispersion delay and fiber-optic steady-phase transmission,and discusses characterization of stability in the frequency domain and time domain.This paper designs a general scheme based on fiber dispersion delay for stable phase transmission,and designs and implements the electronic devices such as frequency multiplier,frequency divider and phase detector in the scheme,which will be realized later.The circuit is uniformly placed on the central station control board and the remote station control board to complete the circuit integration of the central station and the remote station.The designed frequency multiplier can multiply the 10 MHz signal by 208 times and the output power is 1.85 dBm.The realized input power range of the frequency divider is from-30 dBm to 10 dBm,and the output power of the frequency divider is reached.2.49 dBm;the phase detector also has good linearity and precision in its range of use;a user-friendly display interface has been written on the center-end chassis for user convenience.The paper completed the production of the central station chassis and the remote station chassis,and used the completed two chassis to conduct a stable phase transmission of the 10 MHz signal.In the final result,the stability of the phase is improved by about one order of magnitude at 4096 s compared to the system without steady phase compensation.And the Allan variance of the stable phase system reaches 2.01×10-12@1 s and 1.40×10-14@4096 s.Finally,this paper implements a set of high-availability and low-cost stable phase transmission equipment.