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本文提出一种对双相码进行最佳时间检测的光纤数字通信系统的方案,对这种系统的性能作了理论分析。文章指出,对光纤通信来说,双相码是一种最佳信号形式,而门限跨越时刻的检测是一种最大后验统计检验,将两者结合在一起可以构成一种统计检测理论意义上的最佳接收机。作者认为,光纤通信所惯用的幅度检测在具有信号依赖性的光电转换散粒噪声面前无所作为,而门限跨越时间检测却能够减小一切噪声(包括光电转换散粒噪声)对判决错误概率的影响。文章把文献[1]的结果扩展到考虑散粒噪声的情况,给出了时间检测接收机的噪声方差、信噪比和误码率的完整计算方法,并按最大信噪比准则论述了接收机滤波器的最佳化问题。分析与计算实例显示,在相似的工作条件下,所建议的接收机的灵敏度可比惯常的接收机改善2～3dB。
In this paper, a scheme of optical fiber digital communication system for the best time detection of two-phase code is proposed, and the performance of the system is analyzed theoretically. The paper points out that for optical fiber communication, the biphase code is the best signal form, and the threshold crossing time detection is a kind of maximum a posteriori statistical test. Combining the two can form a statistical detection theory The best receiver. The author believes that the amplitude detection used in optical fiber communication does nothing in the presence of signal-dependent optoelectronic conversion shot noise, while the threshold spanning time detection can reduce the impact of all noise (including photoelectric conversion shot noise) on the decision error probability. The paper extends the results in [1] to consider the shot noise, and provides a complete method to calculate the receiver’s noise variance, signal-to-noise ratio and bit error rate. The maximum signal to noise ratio Machine filter optimization problems. Analysis and calculation examples show that under similar operating conditions, the proposed receiver sensitivity can be improved by 2 ~ 3dB than the conventional receiver.