WDM系统中改进的Q值在线检测方法

Improved on-line Q-factor measurement method in wavelength-division-multiplexing systems

提出了一种改进的Q值在线检测方法 ,指出可以使用不同的门限电平分别对空号和传号进行判决 ,并引入噪声系数表征高速光纤通信系统信号噪声的幅度变化范围 ,相应地修正了空号和传号均方差的计算表达式 .基于改进的方法设计了实验方案 ,采用数字信号处理芯片(DSP)技术开发了Q值测试板并进行了模拟测试 .在一定噪声范围内 ,测试结果与理论值吻合得较好 .相比于现有的Q值在线检测方法 ,改进的方法更精确地表示了传输信号的信噪比 。

The principle of an improved method for on-line Q-factor measurement is presented, describing that the space levels and the mark levels can be decided respectively by different thresholds. By introducing a coefficient that denotes the intensity of noise in high-speed optical communication systems, the expressions for calculating the root-mean-square deviation of spaces and marks are modified. Based on the novel method presented, an experiment scheme by the digital signal processor (DSP) approach is designed and a Q-factor testing board is developed. The simulating results coincide with the theoretical values when the optical noise amplitude vibrating in a practical range. With the improved method the signal-to-noise ratio (SNR) of practical systems can be measured more accurately than previously published ones.