推導了一種用于減少定時抖動數字預濾波器的沖激響應表達式，提出了一種數字預濾波器的設計方法，設計了一種優化數字預濾波器。通過對定時恢復環的仿真，討論了環路的收斂情況，比較了所設計的數字預濾波器和無預濾波器時環路定時抖動與信噪比、定時抖動與環路噪聲帶寬、誤碼率與信噪比的數量關系，證實所設計的數字預濾波器對減少定時抖動非常有效。
關 鍵 詞 定時抖動; 預濾波器; 定時恢復; 優化設計; 數字濾波器

Abstract An expression of impulse response was deduced and a kind of optimum design method for digital prefilter is proposed in this paper. Design a kind of optimum digital prefilter. Simulate a timing recovery loop in order to get statistical data about timing jitter. Discuss the convergence characteristic of timing recovery loop. Compare the relation between timing jitter and signal to noise ratio, the relation between timing jitter and noise bandwidth of loop, the relation between symbol error ratio and signal to noise ratio in optimum prefilter and no prefilter. The result of simulation proved this design method has great affection to reduced timing jitter.
Key words timing jitter; prefilter; timing recovery; optimize design; digital filter