【摘要】 复合二次失真 (CSO:Composite Second Order Distortion)是光纤 CATV中最主要的非线性之一 .理论分析表明 :在外调制 CATV中 ,将调制器偏置在最佳偏置点可以消除 CSO,但外调制器最佳偏置点却随时间及环境温度等漂移 ,因而会导致 CSO的严重恶化 .本文提出了一种易于实现的调制器偏置点控制方案 ,并进行了详细的理论分析与实验研究 ,结果显示该方案能够将 5 0～ 5 5 0 MHz宽频带内电视信号 CSO指标抑制在 -65 d B以下 .更多还原

【Abstract】 Composite second order distortion (CSO) is one of the main nonlinear distortion in optical fiber CATV transmission system.In the optical fiber AM CATV externally modulated transmitter,the CSO can be eliminated completely in principle if the modulator is biased in optimal bias point.But the optimal bias point drifts all the time because of the change of temperature and time,therefore the CSO will be badly degenerated.In this paper a novel control loop for biasing the modulator is presented and it is researched in detail,Experimental results agree well with the theoretical analysis and have shown that the CSO is less than -65dB in the wide passband from 50MHz to 550MHz.更多还原