Time And Frequency Transmission Technology Based On The Dual Heterodyne Phase Error Transfer

Since radar has been widely applied in the civil and military fields,the demand of its detection ability has become higher and higher causing the volume of radar is expanding as well,which will lead to the high cost and terrible mobility.To improve the situation,the distributed phase coherent radar is invented by using a number of small and flexible mobile radar arrays to transmit and receive signals by coherent synthesized with synchronization of the time and frequency.Because of the rapid development of microwave photonics,stable time and frequency transmission over optical fiber has become an important method to make sure the time frequency synchronization.However,resistance to environmental interference of optical fiber is not so good,which will deteriorate the quality of the signals,mainly reflected in transmission delay.Therefore,it is very necessary to compensate the transfer delay to recover the signal.This thesis investigates the time-frequency transmission based on the dual-heterodyning phase error transfer(DHPT).In the frequency transmission aspect,the stable high-frequency signal transmission system based on DHPT is introduced.Taking the combination of the DHPT and phase looked loop(PLL)to transfer the high-frequency signal to the remote end,which will improve the stability of the frequency.In the time propagation part,the time delay fluctuation measurement method based on the phase error is demonstrated,whose main issue is the period ambiguity limiting the measurement range.To solve the problem,frequency division and digital combination are proposed:dividing the frequency of the intermediate frequency(IF)signal obtained from the DHPT by N.High frequency signal is applied for high resolution?limited measurement range;low frequency signal is applied for low resolution?wide measurement range.Then the measurement outcomes of these two signals are combined together to obtain the time delay fluctuation with a high resolution and a wide range.This method taking the advantage of the high frequency transmission which can achieve high resolution and solve the period ambiguity,expanding the measurement range.Based on this method,the time delay fluctuation of the 80km optical fiber link is measured:the resolution can achieve 27fs,the measurement range is up to 12.5ns,range-resolution ratio is 4.6×10~5.