微波光纤稳相传输系统中的关键控制技术研究

发布时间：2018-07-15 19:15

【摘要】：微波光纤传输系统因具有损耗低、传输带宽大、电磁兼容等优点,可实现远距离传输,因此得到了广泛的应用。光纤传输微波信号时,光纤折射率和光纤长度随着环境温度、应力等因素变化会对系统产生外加的相位抖动,导致接收端的信号相位不稳定。针对微波光纤传输中电域稳相控制的关键技术,本文采用往返相位校正的方法从相位检测、相位补偿和自适应相位控制三个方面展开研究。(1)相位检测:根据往返相位补偿原理,利用鉴相模块对发送端本地微波信号与接收端反馈回来的信号进行相位差检测。然后鉴相器输出有相位差信息的电压信号,经过嵌入式处理器由模数转换进行信号采样和数据处理,从而完成微波信号相位的检测。同时,为抑制电源和微波器件带来的噪声以提高鉴相精度,设计了专门的电源稳压模块。(2)相位补偿:系统采用模拟微波压控移相器对相位进行补偿。采集到相位差信息之后,通过数模转换输出的模拟电压来调节微波电控移相器的控制电压,由直调激光器调制的微波信号即为相位补偿之后的信号。光纤远程传输后,接收端利用光电探测器进行直接检测,使解调的微波信号相位和发送端微波信号相位实现同步。(3)自适应相位控制:在发送端稳相控制系统中,由于模拟-数字转换模块采集鉴相模块输出的电压带有两倍相位抖动信息,数字-模拟转换输出的电压通过自适应控制算法来实时地控制移相器补偿一倍的相位抖动,从而对微波信号的相位进行自动控制。最后,在实验室组建了系统测试链路,对2.4GHz微波信号传输50km单模光纤的稳相控制系统进行了测试。实验测得2000秒内信号相位抖动小于1.7ps;施加应力的情况下100秒内信号相位抖动小于4.8ps。
[Abstract]:Microwave optical fiber transmission system has been widely used because of its advantages of low loss, large transmission bandwidth and electromagnetic compatibility. When optical fiber transmits microwave signal, the change of fiber refractive index and fiber length with ambient temperature, stress and other factors will produce additional phase jitter on the system, resulting in the signal phase instability at the receiving end. Aiming at the key technology of phase stabilization in electric domain in microwave fiber transmission, this paper studies the three aspects of phase detection, phase compensation and adaptive phase control by using round trip phase correction method. (1) Phase detection: according to the principle of round-trip phase compensation, Phase discrimination module is used to detect the phase difference between the local microwave signal at the transmitter and the signal returned from the receiver. Then the phase discriminator outputs the voltage signal with the phase difference information. The signal is sampled and processed by the embedded processor by analog-to-digital conversion, thus the phase detection of the microwave signal is completed. At the same time, in order to suppress the noise caused by power supply and microwave devices to improve the accuracy of phase detection, a special power supply voltage stabilizer module is designed. (2) Phase compensation: the system uses analog microwave voltage-controlled phase shifter to compensate the phase. After the phase difference information is collected, the control voltage of the microwave electronic controlled phase shifter is adjusted by the analog voltage of the digital-analog conversion output. The microwave signal modulated by the direct-modulated laser is the signal after the phase compensation. After the optical fiber remote transmission, the receiver directly detects the phase of the demodulated microwave signal and the transmitter microwave signal by using photodetector. (3) Adaptive phase control: in the transmitter phase stabilization control system, Because the output voltage of the analog to digital converter module has double phase jitter information, the output voltage of the digital to analog conversion module can be controlled in real time by the phase shifter to compensate for the double phase jitter through adaptive control algorithm. The phase of microwave signal is controlled automatically. Finally, the system test link is set up in the laboratory, and the stable phase control system of 2.4GHz microwave signal transmission 50km single-mode fiber is tested. The experimental results show that the signal phase jitter is less than 1.7psin 2000 seconds and less than 4.8ps in the case of stress.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN925

【相似文献】