一种双向同源相参微波光纤稳相传输系统

A two-way homologous coherent microwave optical fiber stable phase transmission system

在电子对抗系统、雷达系统、卫星导航和深空探测等多个领域中,微波信号经激光器调制后加载到光信号上经过光纤传输后其相位受外界环境的影响,无法实现稳相传输。首次提出了一种双向同源相参微波光纤稳相传输系统,可实现微波信号在光纤中稳相传输。该系统利用恒温晶振产生相位稳定的多路同参基准信号,一路信号用做光纤传输的相位变化识别信号,经激光器调制成光信号,然后由光分路器分出多路光参考信号与需稳相的信号进行同光纤传输;其它同参信号作为基准信号与经过光纤传输的相位识别信号进行鉴相,其中基准信号与参考信号相参,构建2种信号相参的机理,实现以相位变化为参量的鉴相系统,利用参考信号的相位变化完成对传输的宽带射频微波信号相位变化的识别。在鉴相实现过程中,采用双平衡混频器完成对参考信号相位变化实时鉴相,由单片机对参考信号相位的实时变化进行采样,实时控制可调电动延时线(VODL)进行光传输链路光程差的跟踪补偿,完成对需稳相信号和参考信号的相位主动补偿,实现宽带射频微波信号光纤稳相传输。

In many fields,such as electronic countermeasure system,radar system,satellite navigation and deep space exploration,microwave signal is modulated by laser and loaded on the optical signal.After transmitted by optical fiber,its phase is affected by the external environment,so it can not achieve stable phase transmission.In this paper,a two-way homologous coherent microwave optical fiber stable phase transmission system is proposed,which can realize microwave signal's stable phase transmission in optical fiber.In this technique,the constant temperature crystal oscillator is used to generate multi-channel reference signals with stable phase.One signal is used as the phase change identification signal for optical fiber transmission.The signal is modulated into an optical signal by the laser,and then the multi-channel optical reference signal is separated by the optical splitter and the signal to be stabilized is transmitted with the optical fiber.In addition,the same reference signal is used as the reference signal to identify the phase with the phase identification signal transmitted through the optical fiber,and the reference signal and the reference signal are coherent.Two kinds of signal coherence mechanisms are constructed to realize the phase identification system with the phase change as the parameter.The phase change of the reference signal is used to identify the phase change of the transmitted broadband RF microwave signal.In the realization process of phase detection,a double balanced mixer is used to complete the real-time phase detection of the reference signal phase change.The MCU samples the real-time change of the reference signal phase,and controls the adjustable electric delay line(VODL)in real time to track and compensate the optical path difference of the optical transmission link,so as to complete the active phase compensation of the required stable phase signal and the reference signal.It can realize the stable phase transmission of wideband RF microwave signal through optical fiber.